Here - Nanyang Technological University


Organizing Committee

Associate Professor Xiaodong Chen (Chairman)

School of Material Science and Engineering, NTU

Professor Zhenan Bao (Co-Chair)

Department of Chemical Engineering, Stanford University

Professor Bo Liedberg

School of Materials Science and Engineering, NTU

Professor Peng Chen

School of Chemical and Biomedical Engineering, NTU

Assistant Professor Nripan Mathews

School of Materials Science and Engineering, NTU

Symposium Schedule

Nov 16, Monday

8:30 – 9:00 Registration

Session 1

9:00 – 9:15

9:15 – 10:00

10:00 – 10:30

10:30 – 10:50

Session 2

10:50 – 11:20

11:20 – 11:50

11:50 – 12:20

12:20 – 12:50

Session 3

12:50 – 1:10

1:10 – 1:30

1:30 – 2:00

2:00 – 2:30

2:30 – 3:00

3:00 – 3:30

Chair: Xiaodong Chen

Opening Remarks by Prof. Subbu Venkatraman, Chair of MSE

Skin-Inspired Flexible and Stretchable Electronic Sensors

Zhenan Bao, Stanford University

Stretchable Devices for Wearable Healthcare

Dae-Hyeong Kim, Seoul National University

Photo, Coffee Break and Poster Session

Chair: Peng Chen

Printed and Flexible Sensors for Vital Signs Monitoring

Aminy Ostfeld, University of California, Berkeley

Ultrathin Gold Nanowires as New e-Skin Materials for Applications in

Flexible Transparent Conductor and Stretchable Wearable Sensors

Wenlong Cheng, Monash University

Horizontally Aligned CNT Biosensors for Sports Applications

Alfred Tok, Nanyang Technological University


Chair: Nripan Mathews

SPM Characterization of Flexible Materials for Biological Applications

Technical presentation by Bruker Nano Surfaces Division

Technical presentation by Leica Microsystems

Imperceptible Active Sensors for Cyber–physical Systems

Tsuyoshi Sekitani, Osaka University

High Dynamic Range Flexible All-Organic Photo Sensors with an Integrated


Wenping Hu, The Chinese Academy of Sciences

When MEMS Technology Meets Flexible Electronics

Chengkuo Lee, National University of Singapore

CMOS Technology for Free Form Flexible-Stretchable-Reconfigurable


Muhammad Mustafa Hussain, King Abdullah University of Science and


3:30 – 4:00

Session 4

4:00 – 4:30

4:30 – 5:00

5:00 – 5:30

11:30 – 11:40

11:45 –

Coffee Break and Poster Session

Chair: Zhenan Bao

Conductive Inks for 2D and 3D Printed Devices

Shlomo Magdassi, The Hebrew University of Jerusalem

Carbon Nanotube Based Electronic Devices

Qing Zhang, Nanyang Technological University

Construction of Flexible Organic Transistors and Thermoelectric Devices towards Smart Elements

Chong-an Di, The Chinese Academy of Sciences

5:30 – 6:00 Towards Transparent Flexible Devices

Nripan Mathews, Nanyang Technological University

BBQ at President’s Lodge for all speaker and poster presenters 6:00 – 9:00

Nov 17, Tuesday

Session 5 Chair: Bo Liedberg

9:00 – 9:30 Hybrid Transparent Conductor for Deformable Display

Pooi See Lee, Nanyang Technological University

9:30 – 10:00

10:00 – 10:30

10:30 – 11:00

Stretchable and Flexible Transparent Conductive Electrodes

Hyoyoung Lee, Sungkyunkwan University

Coffee Break and Poster Session

Two Dimensional Material based Sensor for Wearable Electronics

Jong-Hyun Ahn, Yonsei University

11:00 – 11:30 Highly Flexible and Wearable Liquid-based Microfluidic Tactile Sensor

Chwee Teck Lim, National University of Singapore

Poster award ceremony and

Closing speech by Prof Russell Gruen, Director of NITHM

Lunch at Fusion Spoon for all speakers


Skin-Inspired Flexible and Stretchable Electronic Sensors

Zhenan Bao

Stanford University, Department of Chemical Engineering, Stanford, California 94305, USA


Skin is the body’s largest organ, and is responsible for the transduction of a vast amount of information. This conformable, stretchable and biodegradable material simultaneously collects signals from external stimuli that translate into information, such as pressure, pain and temperature. The development of electronic sensors, inspired by the complexity of this organ, is a tremendous, unrealized materials challenge. However, the advent of organic and carbon-based electronic materials may offer a potential solution to this longstanding problem. In this talk, I will describe organic and carbon nano-electronic sensors to mimic skin sensing functions. An artificial system that closely mimics the digital nature of human skin mechanoreceptor for neuro-prosthetics using flexible printed organic electronic circuits and pressure sensors will be presented.


Zhenan Bao is a Professor of Chemical Engineering at Stanford

University, and by courtesy, a Professor of Chemistry and

Professor of Materials Science and Engineering. Prior to joining

Stanford University in 2004, she was a Distinguished Member of

Technical Staff at Bell Labs, Lucent Technologies from

1995-2004. She has over 350 refereed publications and over 50 US patents with a Google Scholar H-Index of >110. Bao has served as a Board Member for the National Academy Board on Chemical

Sciences and Technology and Board of Directors for the Materials

Research Society (MRS). She is an Associate Editor for Chemical

Sciences. She serves/served on the international advisory boards for Nature Asia Materials, Journal of American Chemical Society, Advanced Materials,

Advanced Functional Materials, Advanced Energy Materials, Advanced Electronic Materials,

ACS Nano, Chemistry of Materials, Nanoscale, Chemical Communication, Macromolecules,

Organic Electronics, Materials Horizon and Materials Today.

She is also a Fellow of ACS, AAAS, MRS, SPIE, ACS PMSE and ACS POLY. Bao was the recipient of the AICHE Andreas Acroivos Award for Professional Progress in

Chemical Engineering in 2014, ACS Polymer Division Carl S. Marvel Creative Polymer

Chemistry Award in 2013, ACS Author Cope Scholar Award in 2011, Royal Society of

Chemistry Beilby Medal and Prize in 2009, IUPAC Creativity in Applied Polymer Science

Prize in 2008, American Chemical Society Team Innovation Award in 2001 and the R&D

100 Award in 2001. Bao was selected by MIT Technology Review magazine in 2003 as one of the top 100 young innovators. She is among the world’s top 100 materials scientists acknowledged by Thomson Reuters.

She is a co-founder and on the Board of Directors for C3

Nano, a Silicon Valley venture funded start-up commercializing flexible transparent electrodes using nanomaterials.


Stretchable Devices for Wearable Healthcare

Dae-Hyeong Kim



Center for Nanoparticle Research, Institute for Basic Science,


School of Chemical and Biological Engineering,

Seoul National University, Seoul 151-744, Korea

Tel.:82-2-880-1565, E-mail:

Recent advances in soft electronics have attracted great attention due in large to the potential applications in personalized, bio-integrated healthcare devices. The mechanical mismatch between conventional electronic/optoelectronic devices and soft human tissues/organs causes many challenges, such as the low signal to noise ratio of biosensors due to the incomplete integration of rigid devices with the body, inflammations and excessive immune responses of implanted stiff devices originated from friction and foreign nature to biotic systems, and the huge discomfort and consequent stress to users in wearing/implanting these devices. Ultra-flexible and stretchable electronic/optoelectronic devices utilize low system modulus and the intrinsic system-level softness to solve these issues. Here, we describe our unique strategies in the synthesis of nanoscale materials, their seamless assembly and integration, and corresponding device designs towards wearable and implantable healthcare devices. Good examples include wearable quantum dot light emitting diodes

(QLEDs) potentially used for input/output routes for medical information used in integrated healthcare sensors and transdermal therapeutic devices, as well as the multifunctional implantable electronic stent and minimally invasive surgical tools to solve specific cardiovascular and colorectal diseases respectively. These implantable and wearable bio-electronic systems combine recent breakthroughs in unconventional soft electronics to address unsolved issues in clinical medicine, hence providing new opportunities in personalized healthcare.


Dae-Hyeong Kim received his B.S. (2000) and M.S. (2002) degrees from the School of Chemical Engineering at Seoul

National University. He obtained his Ph.D. (2009) from the department of Materials Science and Engineering at the University of Illinois at Urbana-Champaign. Since he joined the faculty of the

School of Chemical and Biological Engineering at Seoul National

University in 2011, he has focused on stretchable electronics for bio-medical and energy applications.


Printed and Flexible Sensors for Vital Signs Monitoring

Aminy Ostfeld and Ana Claudia Arias

Department of Electrical Engineering and Computer Sciences,

University of California, Berkeley, California 94720, USA


In recent years, there has been an increased demand for wearable devices, capable of monitoring stress and human performance during physically demanding tasks and fitness levels. Wearable medical devices, for improved in-home care, customized for patients with known health issues, who can benefit from regular and even continuous monitoring, are also desired. Regular monitoring of vital signs would help to establish an individual’s health statistics baseline and alert users and medical professionals of abnormalities, indicating that further medical attention and care may be necessary. The minimal functionality desired for wearable medical devices requires monitoring of vital signs, such as ECG, temperature, blood oxygenation, pulse rate, blood pressure and respiration rate. We have developed methods to measure pulse rate, blood oxygenation, bio-impedance and temperature using fully printed devices as building blocks for flexible wearable sensing systems. Our sensors are fabricated on flexible substrates using printed technologies, which allow integration of components, hence maintaining the overall sensor flexibility. We have successfully implemented organic light emitting diodes in an all-organic optoelectronic pulse oximeter sensor that functions in transmission and reflection mode. Thermistors are inkjet-printed using a blend of

PEDOT:PSS and nickel oxide nanoparticles. Printed thermistors provide linear response from

25°C to 150°C with a controllable β of 500-1000. Bio-potential and ECG electrodes are inkjet-printed using gold nanoparticle ink, where minimum feature size of 80 µm was achieved with a sheet resistance of 0.4 Ω/sq. Finally, the sensors were interfaced with an analog front-end, a microcontroller, and a Bluetooth chip, to provide ECG signal and accurate body temperature. As part of the flexible system, we have developed flexible lithium ion batteries based on graphite (anode) and lithium cobalt oxide (cathode). The battery operates between 4.2-3.6 V and has a capacity of ~23 mAh (active area = 10.9 cm


) with capacity retention of 99.2% after 100 electrochemical cycles. The battery was able to power a commercial oximeter with 20 mA at a 3.6 V requirement.


Ana Claudia Arias is an Associate Professor at the Electrical

Engineering and Computer Sciences Department at the University of

California, Berkeley, and a faculty director at the Berkeley Wireless

Research Center (BWRC) and the SWARM Lab. Prior to joining the

University of California, she was the Manager of the Printed

Electronic Devices Area and a Member of Research Staff at PARC, a

Xerox Company, in Palo Alto, California. She went to PARC from

Plastic Logic in Cambridge, UK, where she led the semiconductor device group. She received her Ph.D. on semiconducting polymer blends for photovoltaic devices from the Physics Department at the

University of Cambridge, UK. Prior to that, she received her master and bachelor degrees in physics from the Federal University of Paraná

in Curitiba, Brazil. Her research focuses on devices based on solution processed materials and applications development for flexible sensors and electronic systems. She is also the Chair of the Thin Film Electronics Technical Advisory Council.


Ultrathin Gold Nanowires as New e-Skin Materials for Applications in

Flexible Transparent Conductor and Stretchable Wearable Sensors

Wenlong Cheng



Department of Chemical Engineering, Monash University, Room 302, NH Building 82,

Melbourne, Victoria 3800, Australia

2 Melbourne Centre for Nanofabrication, 151 Wellington Road, Melbourne, Victoria 3800,



Group Page:

Future electronic devices will be soft and stretchable, enabling applications which were previously impossible to achieve with existing rigid circuitry board technologies.

However, we need new materials and/or new design principles. In this talk, I will describe our recent success in using ultrathin gold nanowires as a new class of electronic skin (e-skin) material. We demonstrated their applications as flexible transparent conductor


and in highly stretchable wearable sensors 2-4 . In particular, we could obtain highly stretchable nano-patches or tattoos, which are body attachable, and could be integrated into textile, enabling monitoring of wrist pulses, hand gestures, body motions and controlling robotic arms in a wireless fashion. I will also briefly cover our recent work in the fabrication of flexible/stretchable sensors with bio-inspired design


and copper nanowires




Wenlong Cheng is a full professor in the Department of Chemical

Engineering at Monash University, Australia. He earned his Ph.D. from the Chinese Academy of Sciences in 2005 and his B.S. from Jilin

University, China in 1999. He held positions in the Max Planck

Institute of Microstructure Physics and the Department of Biological and Environmental Engineering in Cornell University before joining

Monash University in 2010. His research interest lies at the nano-bio interface, particularly addressing plasmonic nanomaterials, DNA nanotechnology, nanoparticle anticancer theranostics and electronic skin. He has published ~70 papers, including 3 in Nature

Nanotechnology, 1 in Nature Materials and 1 in Nature



Y. Chen, Z. Ouyang, M. Gu and W. L. Cheng*, “Mechanically Strong, Optically

Transparent, Giant Metal Superlattice Nanomembranes From Ultrathin Gold Nanowires,”

Advanced Materials, 2013, 25, 80-85.


S. Gong, W. Schwalb, Y. Wang, Y. Chen, Y. Tang, J. Si, B. Shirinzadeh and W. L.

Cheng*, “A wearable and highly sensitive pressure sensor with ultrathin gold nanowires,”

Nature Communications, 2014, 5, 3132.


S. Gong, D. T. H. Lai, B. Su, K. J. Si, Z. Ma, L. W. Yap, P. Guo and W. L. Cheng*,

“Highly Stretchy Black Gold E-Skin Nanopatches as Highly Sensitive Wearable

Biomedical Sensors,”

Advanced Electronic Materials, 2015, DOI:



S. Gong, D. Lai, Y. Wang, L. W. Yap, K. J. Si, Q. Shi, N. N. Jason, T. Sridhar, H. Uddin and W. L. Cheng*, “ Tattoo-like Polyaniline Microparticle-Doped Gold Nanowire Patches as Highly Durable Wearable Sensors,” ACS Applied Materials and Interfaces, Accepted,



B. Su*, S. Gong, Z. Ma, L. W. Yap and W. L. Cheng*, “Mimosa-inspired design of flexible pressure sensor with touch sensitivity,” Small, 2014, DOI:



N. N. Jason, W. Shen and W. L. Cheng*, “Copper Nanowires as Conductive Ink for

Low-Cost Draw-On Electronics,” ACS Applied Materials and Interfaces, 2015, 7,



Y. Tang, S. Gong, Y. Chen, L. W. Yap and W. L. Cheng*, “Manufacturable Conducting

Rubber Ambers and Stretchable Conductors from Copper Nanowire Aerogel

Monoliths,” ACS Nano, 2014, 8, 5707-5714.


Horizontally Aligned CNT Biosensors for Sports Applications

Hu Chen


, Jingfeng Huang


, Alagappan Palaniappan


, Bo Liedberg


, Mark Platt



Alfred Iing Yoong Tok 1,2,*


School of Materials Science and Engineering,

Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798


Institute for Sports Research,

Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798


Centre for Biomimetic Sensor Science,

Nanyang Technological University, 50 Nanyang Drive, Singapore 637553


Department of Chemistry, Centre for Analytical Science, Loughborough University,

Loughborough, Leicestershire LE11 3TU, UK

*Presenting author

An ultra-sensitive and miniaturized biosensor is widely needed for real time monitoring in the field of sports science. In this work, we present a novel biosensor based on horizontally aligned carbon nanotubes (CNTs) with great potential for various applications in sports science. The CNTs were synthesized on quartz substrates, followed by device fabrication. As a demonstration of their biosensing capability, the developed devices were used for the detection of interleukin-6 (IL-6), a key biomarker for the prevention of sports science issues, such as over-training. The experimental results revealed that the as-prepared sensors responded to the biomarkers immediately in the range of 10-100 ng/mL and the limit-of-detection (LOD) was 1 pg/mL. By virtue of the rapid sensor response, excellent sensitivity and good portability, the CNT-based biosensor presented is an ideal candidate for real time monitoring of athletes in training sessions as the sensing molecules can easily be developed to sense a host of other sport-related biomarkers.


Alfred Tok (PK; Ph.D., NTU; C.Eng, MIMMM; MBA, NTU) has been a faculty member in the School of Materials Science and Engineering (MSE) since 2003. He studied Mechanical

Engineering at the Queensland University of Technology,

Australia, and graduated with First Class honours in 1995. He was also conferred the Dean's Award for Excellence for being the top graduate on the course. After graduation, he worked as a mechanical engineer at ST Aerospace Engineering. In 1997, he was awarded 2 scholarships at Nanyang Technological

University to pursue his Ph.D. in Mechanical Engineering. He obtained his MBA (Dean’s

List) in 2009 from the Nanyang Business School, and in 2009, he was appointed Division

Head of Materials Technology in MSE (till 2012). Since 2011, he has been the Deputy

Director of the Institute for Sports Research in NTU. He also consults extensively for companies from various industries.


Imperceptible Active Sensors for Cyber-Physical Systems

Tsuyoshi Sekitani, Teppei Araki, Shusuke Yoshimoto, Takafumi Uemura

The Institute of Scientific and Industrial Research, Osaka University

8-1, Mihogaoka, Ibaraki, Osaka 567-0047, Japan


In this talk, I will discuss the recent progresses and future prospects of large-area, ultra-flexible and ultrathin electronic sensors. Our work focuses on integration technologies of thin-film electronics comprising ultra-soft gel electrodes, thin-film amplifier, Si-LSI platform, thin-film battery, and information engineering, which are all integral for the realization of imperceptible active sensors. Here, I would like to demonstrate the applications of imperceptible sensors for patch-type bio-signal monitoring sheets. These sensors serve as an important part of seamless cyberspace/real-world interfaces that are commonly referred to as cyber

 physical systems (CPSs).

On the basis of our initial work on manufacturing different flexible organic devices, including TFTs, LEDs, and PDs, we developed ultra-flexible electronics for applications that use large-area sensors, actuators, memories, and displays


. For example, by taking advantage of an ultra-flexible and compliant amplifier that can amplify biological signals by

500×, we developed 1 µm thick multi-channel active matrix electrocardiogram and electromyogram monitoring systems. Ultrathin electronics with a total thickness of approximately 1-2 µm support a bending radius of less than 10 µm.


Tsuyoshi Sekitani received his Ph.D. in applied physics from the

University of Tokyo, Japan in 2003. From 1999-2003, he was with the Institute for Solid State Physics at the University of

Tokyo. From 2003- 2010, he was a Research Associate, and in

2011, he was an Associate Professor in the School of

Engineering at the University of Tokyo. In 2014, he was made a professor in The Institute of Scientific and Industrial Research at

Osaka University. His current research interests include organic transistors, flexible electronics, plastic integrated circuits, large-area sensors, and plastic actuators. He is a member of the

Japanese Society of Applied Physics (JSAP) and the Materials

Research Society (MRS). He has received more than 27 awards, including the Young

Scientist Award from the Minister of Education, Culture, Sports, Science and Technology,

Japan, and the IEEE Paul Rappaport Award in 2009 and 2010 (Best Paper at the IEEE

Transactions on Electron Devices in 2009 and 2010). In 2014, he was acknowledged as one of the “Highly Cited Researchers” (The World’s Most Influential Scientific Mind) by Thomson



T. Sekitani, et al., Nature Materials, 6, 413 (2007).


T. Sekitani, et al., PNAS, 105, 4976 (2008).


T. Sekitani et al., Science, 321, 1468 (2008).


T. Sekitani, et al., Nature Materials, 8, 494 (2009).


T. Sekitani, et al., Science, 326, 1516 (2009).


T. Sekitani, et al., Nature Materials, 9, 1015 (2010).


K. Kuribara, et al., Nature Communications, 3, 723 (2012).


M. Kaltenbrunner, et al., Nature Communications, 3, 770 (2012).


T. Yokota, et al., IEEE Transactions on Electron Devices, 59, 3434 (2013).


M. Kaltenbrunner, et al., Nature, 499, 458 (2013).


M. S. White, et. al., Nature Photonics, 7, 811 (2013).


S. Lee, et. al., Nature Communications, 5, 5898 (2014).


M. Melzer, et. al., Nature Communications, 6, 6080 (2015).

High Dynamic Range Flexible All-Organic Photo Sensors with an

Integrated Architecture

Hanlin Wang 1,2 , Hongtao Liu 1 , Qiang Zhao 1,2 , Cheng Cheng 1 , Wenping Hu 1, Yunqi Liu 1



Beijing National Laboratory for Molecular Sciences, Key Laboratory of Organic Solids,

Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China


University of Chinese Academy of Sciences, Beijing 100049, China


Organic materials can complement conventional inorganic materials for cost-effective optoelectronics, such as photo sensors. However, due to difficulties in integration of organic components, the exploration of all-organic photo sensors remains a challenge. Here, we demonstrate multi-component integrated, all-organic photo sensors with an overall dynamic range of nearly 10


. Based on photoconductivity differences in organic dyes, a photosensitive voltage divider is realized by a series connection of organic resistors.

By virtue of an organic field-effect transistor as an amplifier, grey scale sensing is achieved in our pixels. The devices are ultrathin (470 nm) and extremely light, (850 mg m


), however, they continue to be operational when folded with a bending radius of 5 µm. The innovative combination of organic components, together with the simplicity of our processing technique, might provide opportunities for smart plastic optoelectronics, such as remote control devices and emerging health monitoring systems.


Wenping Hu is a Professor at the Institute of Chemistry, Chinese

Academy of Sciences. He received his Ph.D. from the same institute in 1999. Subsequently, he joined Osaka University and

Stuttgart University as a Research Fellow, funded by the Japan

Society for the Promotion of Sciences and Alexander von

Humboldt Fellowship, respectively. In 2003, he worked in

Nippon Telephone and Telegraph (NTT), and then joined the

Institute of Chemistry, Chinese Academy of Sciences, and was promoted to full professor. He served as a Visiting Scholar at the

Department of Chemistry, Stanford University in 2007 and was a

Visiting Professor at the Department of Chemistry, National

University of Singapore in 2013. He focuses on organic optoelectronics and has published 4 books (Organic Optoelectronics, Wiley, etc.) and more than 350 peer-reviewed papers with total citations >10,000. He is a member of the editorial boards for several journals (e.g., Advanced Energy Materials, Advanced Electronic Materials,

Nano Research, Science China Chemistry, Science Bulletin, Science China Materials), and is now an Associate Editor of Polymer Chemistry.


When MEMS Technology Meets Flexible Electronics

Chengkuo Lee

Singapore Institute for Neurotechnology (SINAPSE)

Centre for Sensors and MEMS

Department of Electrical and Computer Engineering

National University of Singapore

The advance in MEMS technology has brought significant impact on human life.

Inertial sensors have dominated many innovative and profitable commercial applications in the past few years. Ranging from wearable electronics to inter-of-things (IoT), more and more

MEMS sensors have become the enabling technology for novel applications. The combination of flexible electronics, flexible and stretchable sensors, MEMS sensors, microfluidics and energy harvesters will form a new platform for healthcare applications. In this talk, such platforms will be highlighted, while transdermal drug delivery and neural interfaces are introduced as demonstrators.


Chengkuo Lee received his Ph.D. in Precision Engineering in February

1996 from the University of Tokyo. He worked as a JST Research

Fellow in the Mechanical Engineering Laboratory, AIST, MITI, Japan in 1996.

He was an Adjunct Assistant Professor in the Electrophysics

Department at the National Chiao Tung University, Hsinchu, Taiwan, in

1998, and an Adjunct Assistant Professor at the Institute of Precision

Engineering at National Chung Hsing University, Taichung, Taiwan, from 2001-2005. In August 2001, he co-founded Asia Pacific

Microsystems, Inc. (APM), in Hsinchu, Taiwan, where he became Vice President of R&D before becoming Vice President of the optical communication business unit. He was also in charge of international business and technical marketing for the MEMS foundry service. From

2006-2009, he was a Senior Member of the Technical Staff at the Institute of Microelectronics,

A*STAR, Singapore. Currently, he is an Associate Professor in the Department of Electrical and Computer Engineering, and the Director of Centre for Intelligent Sensors and MEMS at

National University of Singapore. He is the co-author of Advanced MEMS Packaging

(McGraw-Hill, 2010) and Micro- and Nano-Energy Harvesting Technologies (Artech House,

2015). He has contributed to more than 250 international conference papers and extended abstracts, and 185 peer-reviewed international journal articles in the fields of sensors, actuators, energy harvesting, MEMS, lab-on-chip, NEMS, nanophotonics and nanotechnology.


CMOS Technology for Free Form Flexible-Stretchable-Reconfigurable


Muhammad Mustafa Hussain

Integrated Nanotechnology Lab, Electrical Engineering, Computer Electrical Mathematical

Science and Engineering Division, King Abdullah University of Science and Technology

(KAUST), Thuwal 23955-6900, Saudi Arabia


Complementary metal oxide semiconductor (CMOS) technology has served as a critical catalyst to the rise and prominence of our digital world. Singular focus on performance per cost has driven CMOS technology to be increasingly mature and reliable in batch fabrication of high quality electronics, based on predominantly mono-crystalline thin film materials, like silicon, gallium nitride, III-V materials, etc. However, they are often rigid, brittle and opaque. This restricts their usage in emerging free form flexible-stretchable-reconfigurable electronics. In my talk, I will discuss how CMOS technology can be used to transform such physically unbendable but state-of-the-art electronics into flexible-stretchable-reconfigurable electronics, while retaining their high performance, energy efficiency, ultra-large-scale-integration (ULSI) density and performance per cost benefit. I will discuss integration strategies to rationally design materials, processes and devices to facilitate this transformation. To do so, I will use examples focusing on healthcare and environmental monitoring, which are commercially relevant or under commercialization. Specially looking forward, we need to specify the attributes of electronics, which will enable Internet of Everything, where nearly every object will be smart, informative, interactive and resourceful to augment the quality of our life. In the past few years, my group has particularly focused on defining such attributes, where we see live

(interactive), physically free form and democratized (easy and simple to use, make and afford) electronics, which can realize wide deployment of electronics for smart living and sustainable future.


Before joining KAUST, Muhammad Mustafa Hussain (Ph.D., ECE, UT

Austin, December 2005) was Program Manager of the Emerging

Technology Program in SEMATECH, Austin. His program was funded by DARPA NEMS, CERA and STEEP programs. A regular panelist of

US NSF grants reviewing committees, he is the Editor-in-Chief of

Applied Nanoscience (Springer) and an IEEE Senior Member. He has served as first or corresponding author in 75% of his 214 research papers (including 15 cover articles and 87 journal papers). He has 15 issued and pending US patents. His students are now serving as faculty members and researchers in KFUPM, UC Berkeley, TSMC, KACST and DOW Chemicals. Scientific American has listed his research as one of the Top 10 World

Changing Ideas of 2014. He has received 19 research awards including this year’s

Outstanding Young Texas Exes Award 2015 (UT Austin Alumni Award) and US National

Academies’ Arab-American Frontiers of Engineering, Science and Medicine 2015.


Conductive Inks for 2D and 3D Printed Devices

Shlomo Magdassi

The Hebrew University of Jerusalem, Jerusalem 91904, Israel


Nanomaterials have unique properties which enable their utilization in functional printing. Our research is focused on synthesis and formulations of nanoparticles and inks, and their utilization in printed devices. The formation and application of conductive inks composed of silver, copper, copper@silver will be reported. These inks address a major challenge in fabrication of flexible electronic devices, in which the printing should be performed desirably at sufficiently low temperatures, which will not damage the polymeric substrates. Our recent discoveries of achieving high conductivity by sintering even at room temperature will be discussed. The fabrication of optoelectronic devices, such as smartphone touchscreens and smart windows, will be presented, based on combining low sintering temperature concepts with directed wetting and self-assembly processes. Application of 3D printing technologies for fabrication of electrodes, comprising responsive shape memory objects, will be also demonstrated.


Shlomo Magdassi is a Professor of Chemistry at the Casali Center of Applied Chemistry, the Institute of Chemistry and the Center for

Nanoscience and Nanotechnology at the Hebrew University of

Jerusalem, Israel. His research focuses on formation, formulation and applications of micro- and nanoparticles. These particles can be used as active components in functional inks and coatings, for example, conductive inks for electronic devices, and 2D and 3D functional printing. In addition to his scientific publications, he has various inventions on applications of colloids in industrial products, which led to some industrial activities, such as worldwide sales and establishing new companies. For more information, please see:


Carbon Nanotube Based Electronic Devices

Qing Zhang

Centre for Micro-/Nano-electronics (NOVITAS), School of Electrical and Electronic

Engineering, Nanyang Technological University, Singapore

Tel: (+65) 6790-5061, E-mail:

In this talk, I shall review our recent research activities on carbon nanotubes (CNTs) based electronic devices. The talk can be divided into four parts, i.e., functionalized CNTs for sensing applications, CNTs-based soft electronics, CNTs-based OLED drivers and

CNTs-based soft Li-ion batteries.

We found that a semiconducting-to-metallic CNT transition can be realized upon dichlorocarbene functionalization. The transition is reversible upon thermal annealing under ambient conditions. The electrical properties of m-CNTs remain largely unaffected whereas the on-state conductivity of s-CNTs is greatly reduced by this process. This is in agreement with relevant theoretical predictions. We also found that after covalently functionalized with 10 µM

4-BBDT solution, the CNT network can be used as a promising humidity sensing element.

We employed a novel post transfer technique to prepare CNT-based soft electronic devices. All CNT devices are initially fabricated on a hard substrate and subsequently encapsulated onto polyimide (PI) and peeled off from the hard substrate to form flexible devices. The soft transfer medium used here serves as the flexible substrate after a plastic transformation process so that the devices and circuits are encapsulated onto the flexible plastic, in favour of high flexibility and reliability.

We also demonstrated the first CNT-based thin film transistor (TFT) driver circuits for static and dynamic AM OLED display with 6 × 6 pixels. High device yields and performance uniformity are achieved using randomly-grown SWNT networks as the active channel material for the TFTs. High device mobility of ~45 cm



-1 s


and the high channel current on/off ratio of

~10 5 of the CNT-TFTs fully guarantee the control capability to the OLED pixels.

We confirmed a layer-by-layer assembly technique as a facile and scalable method to prepare a multilayer Si/CNT coaxial nanofiber anode which possesses storage capacity above 1 mAh cm -2 . The prepared Si/CNT coaxial nanofiber anodes show excellent cyclability. The excellent performance of the Si/CNT coaxial nanofiber multilayer anodes is attributed to the unique nanostructure. The CNT network matrix offers mechanical support to accommodate the stress associated with the large volume change of Si coating and the nanoporous multilayer structure provides continuous paths for Li ion and electron transport. In addition, we developed high capacity 3D current collectors for flexible battery electrodes. We grew vertically aligned

CNT arrays directly on carbon cloth (CC) as a hierarchical 3D current collector and load amorphous Si onto the CNT array with a large areal mass density. Benefiting from the porous structure and hierarchical 3D conductive pathway, the as-synthesized hierarchical 3D CNT-Si

arrays on CC electrode exhibits a high areal capacity up to 3.32 mAh cm


at a current density of

0.2 mA cm


, which is superior cycle performance with a capacity retention of 94.4% after 200 cycles at a high current density of 1 mA cm -2 , and excellent rate capability.


Qing Zhang is a Professor and the Director of Centre of

Micro-/Nano-electronics at the School of Electrical and Electronic

Engineering, Nanyang Technological University, Singapore. His research interests cover nanomaterials and nano/micro-electronic devices, carbon/silicon based thin films, etc. His attention is focused on carbon nanotube and other 0-D, 1-D and 2-D nanostructure based devices and fundamentals, etc.


Construction of Flexible Organic Transistors and Thermoelectric Devices towards Smart Elements

Chong-an Di and Daoben Zhu

Key Laboratory of Organic Solids,

Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China


Organic devices are promising candidates for next-generation flexible smart products, owing to their intrinsic light weight, prominent flexibility, and potential for low-cost development.


Benefiting from systematic studies on functional materials and device engineering, 3,4 we report a series of flexible sensing devices, such as pressure sensors, chemical-/bio-sensors, magnetic sensors utilizing organic thin-film transistors (OTFTs) and organic thermoelectric devices (OTEs).


As an example, we propose the construction of flexible suspended gate OTFTs (SGOTFTs) using a simple lamination method.


By combining OTFTs with a suspended gate device geometry, the SGOTFTs provide an effective way for ultra-sensitive pressure detection. The fabricated devices displayed an unprecedented sensitivity of 192 kPa


and a low limit-of-detection pressure of 0.5 Pa, which was achieved by fine-tuning the material properties of the suspended gate, allowing their applications in health monitoring and spatial pressure mapping.


More recently, we demonstrated temperature-pressure dual-parameter sensors, utilizing microstructure-frame-supported organic thermoelectric (MFSOTE) materials by utilizing combined thermoelectric and piezo-resistive effects in a single device.


The effective transduction of temperature and pressure stimuli into two independent electrical signals permits the instantaneous sensing of temperature and pressure with an accurate temperature resolution of 0.1 K and a high pressure sensing sensitivity of up to 28.7 kPa -1 . The excellent sensing performance, prominent flexibility and self-powered features of the MFSOTE devices make them promising candidates in several artificial intelligence and health-care systems.


Chong-an Di received his Ph.D. in chemistry from the Institute of

Chemistry, Chinese Academy of Sciences (ICCAS) in 2008. He was appointed Assistant Professor in 2008 and promoted to Associate

Professor in 2010 at ICCAS. He visited University of Cambridge and

Stanford University as a visiting and senior visiting academic in 2011 and 2013, respectively. Currently, his research focuses on the investigation of organic field-effect transistors and organic thermoelectric devices. Since 2005, he has authored or co-authored more than 100 peer-reviewed articles in Accounts of Chemical

Research, Nature Communications, Journal of the American

Chemical Society, Advanced Materials, etc., and is named in 12 patents.


C. A. Di, F. J. Zhang, D. B. Zhu, Advanced Materials, 2013, 25, 313.


Y. P. Zang, F. J. Zhang, C. A. Di, D. B. Zhu, Materials Horizon, 2015, 2, 140.


Y. Zhao, C. A. Di, X. K. Gao, Y. B. Hu, Y. L. Guo, L. Zhang, Y. Q. Liu, J. Z. Wang,

W. P. Hu, D. B. Zhu, Advanced Materials, 2011, 23, 2448.


F. J. Zhang, Y. B. Hu, T. Schuettfort, C. A. Di, X. K. Gao, C. R. McNeil, L. Thomsen,

S. C. B. Mansfeld, W, Yun, H. Sirringhaus, D. B. Zhu, Journal of the American

Chemical Society, 2013, 135, 2338.


F. J. Zhang, C. A. Di, N. Berdunov, Y. Y. Hu, Y. B. Hu, X. K. Gao, Q. Meng, H.

Sirringhaus, D. B. Zhu, Advanced Materials, 2013, 25, 1401.


Y. P. Zang, F. J. Zhang, D. Z. Huang, C. A. Di, Q. Meng, X. K. Gao, D. B. Zhu,

Advanced Materials, 2014, 26, 2862.


Y. P. Zang, F. J. Zhang, D. Z. Huang, X. K. Gao, C. A. Di, D. B. Zhu, Nature

Communications, 2015, 6, 6269.


F. J. Zhang, Y. P. Zang, D. Z. Huang, C. A. Di, D. B. Zhu, Nature Communications,

2015, Accepted.


Towards Transparent Flexible Devices

Nripan Mathews

School of Materials Science and Engineering

Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798

Transparent semiconductors and devices allow for the development of novel applications that can be integrated facilely onto a wide variety of surfaces. The development of new material sets have to be combined with techniques for reducing the processing temperatures and unlocking functionalities, such as printability. This talk will focus on the development of amorphous metal oxide semiconductors for thin film transistor applications.

The effect of post processing protocols and cationic substitution in the realization of an all-transparent transistor will be elucidated.


Nripan Mathews is an Assistant Professor at Nanyang Technological

University, Singapore, where he holds a joint position at the School of

Materials Science and Engineering and Energy Research Institute @

NTU. His research focuses on solution-processed electronic materials for applications in electronics and solar energy conversion. He is a recipient of the TR35@Singapore Award 2014 and the

A*STAR-SNAS Young Scientist Award. His work has led to ~100

SCI journals publications with an H-Index of 30.


Hybrid Transparent Conductor for Deformable Display

Pooi See Lee

School of Materials Science and Engineering

Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798


There is an impending need for transparent, yet conducting substrates to realize next generation consumer devices with flexible and deformable functionalities. There are fueling demands for alternative flexible displays, including electrochromics and electroluminescent devices, which require transparent conducting electrodes. The conducting electrodes in displays ideally possess superior conductivity and optical transparency under extreme conditions, such as folding, stretching, flexing, rolling or crumpling. In this talk, I will illustrate our approach in fabricating solution-processed hybrid transparent conductors, and their applications in electrochromics and electroluminescent devices.

We have developed a transfer method to prepare hybrid transparent conductors with high figure of merit. This effective transfer method improves the interface properties and bonding stability between the conductive constituents and the matrix. Superior mechanical properties and excellent electrical conductivity can be achieved. The transparent conductor possesses active surfaces that improve the interfacial properties with the overlay active materials with enhanced electron conduction, charge distribution, and ionic diffusion. We demonstrate the foldable transparent conductors for flexible wearable electrochromics devices. In addition, we show that stretchable electrochromics and electroluminescent devices can also be fabricated using metallic nanowires with polydimethylsiloxane matrix, indicating the promising potential of metallic nanowires based transparent conductors for deformable display applications.


Pooi See Lee is a Professor in the School of Materials Science and

Engineering, Nanyang Technological University, Singapore. She obtained her B.Sc. (Honours) and Ph.D. from the National University of

Singapore. Her research work focuses on the theme of electrochemical- and electrical-inspired devices based on nanostructures and nanocomposites for applications in electrochromics, energy storages, actuators, ferroelectrics, electrical memory devices, sensors, flexible and stretchable electronics.


Stretchable and Flexible Transparent Conductive Electrodes

Hyoyoung Lee



Center for Integrated Nanostructure Physics, Institute for Basic Science (IBS),

Sungkyunkwan University, Suwon 440-746, Korea


Department of Chemistry, Department of Energy Science, SKKU Advanced Institute of

Nano Technology (SAINT), Sungkyunkwan University, Suwon 440-746, Korea

Recently, silver nanowires (AgNWs) have attracted considerable interest for their potential applications in stretchable and flexible transparent conductive films (TCFs).

However, one challenge for commercialization of AgNW-based TCF is low conductivity and low stability caused by weak adhesion forces between AgNWs and the substrate. Thus, the adhesion force especially for attachment of AgNWs to the various kinds of substrates, including plastic substrate for flexible and stretchable electrodes, becomes the most important issue.

Here, we report stretchable and flexible transparent conductive AgNW films, which were prepared by using two-dimensional (2-D) hydrophilic graphene oxide nanosheet (GO) as an over-coating layer (OCL) on the hydrophilically surface-treated plastic film 1 . In addition, poly(diallyldimethyl-ammonium chloride) (PDDA) was introduced as an adhesive agent onto



. Further, the use of GO and PDDA for OCL was introduced via layer-by-layer (LbL) assembly technique. We demonstrated that PDDA could increase the adhesion between

AgNW and substrate to form a uniform AgNW network, and could also serve to improve the stability of GO OCL


. Our AgNW-PDDA-GO composite TCF is stable after exposure to H


S gas or sonication


. Furthermore, for the stretchable TCF, polydimethylsilaoxane (PDMS) surface with various silane compounds, which have functional groups with different degree of sigma (σ)-donating ability and polarity, was modified. We observed different interfacial states depending on terminated functional heap groups of molecularly self-assembled substrate. The surface surrounded by [3-(2-aminoethylamino)propyl]trimethoxysilane exhibited the strongest contact force on the substrate, especially on the junction side, and the longest maintenance of hydrophilicity by coordination-type bonding. As a result, AgNWs adhered permanently to stretchable substrates while simultaneously maintaining high transparency and high conductivity, which suggests excellent mechanical durability, hence exhibiting enhanced performance of flexibility and stretchability


. Finally, we report a novel method to prepare new hybrid rGO-AgNP conducting film by carefully designed reduction duality of formic acid at low temperature, which can be stretched




Hyoyoung Lee received his B.S. and M.S. degrees in chemistry at Kyung

Hee University, Korea in 1989 and 1991, respectively. He received his

Ph.D. at the Department of Chemistry, University of Mississippi, USA, in

1997. He was subsequently a Postdoctoral Associate at North Carolina

State University, USA, from 1997-1999 and POSTECH, Korea, from

1999-2000. He worked at the Electronics and Telecommunications

Research Institute (ETRI) from 2000-2009 as team leader. He then moved to Sungkyunkwan University and has served as a full professor at the

Department of Chemistry, lecturing Organic Chemistry. He served as a director of National

Creative Research Initiatives (NCRI), Center of Smart Molecular Memory from 2006-2015 and has also served as an Associate Director of Institute of Basic Science (IBS) at SKKU. His current research areas are on organic semiconducting materials and devices including molecular/organic memory, OLED, OTFT, sensors, energy storage, graphene oxide, reduced graphene oxide, 2D TMD and MXenes . He has written more than 100 journal articles. He is also a member of the Korean Chemical Society (KCS), Materials Research Society (MRS) and

American Chemical Society (ACS).


In Kyu Moon et al., “2D Graphene Oxide Nanosheets as an Adhesive Over-Coating

Layer for Flexible Transparent Conductive Electrodes”, Scientific Reports, 3, 1112;

DOI: 10.1038/srep01112, 2013.


Y. Li et al., "Highly Bendable, Conductive and Transparent Film by an Enhanced

Adhesion of Silver Nanowires", ACS Applied Materials and Interfaces, 5(18),

9155-60, 2013.


H. Lee et al., "High Mechanical and Tribological Stability of an Elastic Ultrathin

Overcoating Layer for Flexible Silver Nanowire Films”, Advanced Materials, 13,

2252-9, 2015.


H. Lee et al., “Well-ordered and High Density Coordination-type Bonding to

Strengthen Contact of Silver Nanowires on Highly Stretchable Polydimethylsiloxane”,

Advanced Functional Materials, 24 (21), 3276-3283, 2014.


Yeoheung Yoon, et al., “Highly Stretchable and Conductive Silver Nanoparticle

Embedded Graphene Flake Electrode Prepared by In-situ Dual Reduction Reaction”,

Scientific Reports, 2015.


Two-Dimensional Material Based Sensor for Wearable Electronics

Jong-Hyun Ahn

School of Electrical & Electronic Engineering, Yonsei University, Seoul 120-749, Korea

Two-dimensional (2-D) materials, including graphene and transition metal dichalcogenides, provide outstanding properties that can be integrated into various flexible and wearable electronic devices in a conventional, scalable fashion. The mechanical, electrical and optical properties of 2-D materials make it attractive for applications in wearable electronics, biosensors, and other systems. Here, we report flexible (or stretchable) tactile sensors composed of large area 2-D materials grown by chemical vapor deposition method. 2-D material based sensors were integrated on ultrathin plastic substrates and even human skin. This ultrathin 2-D material based sensor has shown good characteristics in terms of sensitivity, linearity, hysteresis and repeatability even on a human fingertip.


Jong-Hyun Ahn received his Ph.D. from the

Department of Materials Science and Engineering,

POSTECH, Korea. He has published more than 120 papers in SCI-listed journals, including articles published on Science (2), Nature (1), Nature Materials

(1), Nature Photonics (1), Nature Nanotechnology (3) and Nano Letters (8). His total citation number is over



Highly Flexible and Wearable Liquid-based Microfluidic Tactile Sensor



, Joo Chuan Yeo


, Chwee Teck Lim



NUS Graduate School for Integrative Sciences and Engineering,

National University of Singapore, Singapore 117456


Centre for Advanced 2D Materials and Graphene Research Centre,

National University of Singapore, Singapore 117546

3 Department of Biomedical Engineering, National University of Singapore, Singapore 117575


Mechanobiology Institute, National University of Singapore, Singapore 117411


# both authors contributed equally to this work

We developed a novel liquid-based resistive microfluidic tactile sensor that possesses high flexibility, durability and sensitivity. The tactile sensor comprises a soft elastomer-based microfluidic template encapsulating a conductive liquid, which serves as the active sensing element of the device. This sensor is capable of distinguishing and quantifying the various user-applied mechanical forces it is subjected to, like pressing, stretching, and bending. In addition, owing to its unique and durable structure, our wearable sensing device is highly deformable and able to withstand strenuous mechanical deformations, such as foot stomping and car crushing, without compromising its electrical signal stability and overall integrity. As a proof-of-concept of the applicability of our tactile sensor, we demonstrate the recognition, differentiation, and measurements of distinct hand muscle-induced motions, including handgrip strength and localized dynamic foot pressure. Overall, this work highlights the potential of the liquid-based microfluidic tactile sensing platform in a wide range of applications and further facilitates the exploration and realization of functional liquid-state device technology.


Chwee Teck Lim is a Provost’s Chair Professor at the National

University of Singapore. He is also the Group Head for the Centre for

Advanced 2D Materials. Chwee Teck Lim has authored more than 275 journal papers (including 40 invited/review articles), 26 book chapters and delivered more than 270 invited talks. He is also on the editorial boards of 14 journals and co-founded four startup companies. He has won more than 50 research awards and honours, including the Vladimir

K. Zworykin Award in 2015, Outstanding Researcher Award and

Outstanding Innovator Award in 2014, the Credit Suisse

Technopreneur of the Year Award, Wall Street Journal Asian

Innovation Award (Gold) in 2012, TechVenture Rising Star Innovator

Award and President's Technology Award in 2011 and the IES Prestigious Engineering

Achievement Award in 2010, among others. His research has previously been cited by the

MIT Technology Review magazine as one of the top ten emerging technologies that will

"have a significant impact on business, medicine or culture"

Poster abstract

































Ela   Sachyani

Zhang   Jing

Guofa   Cai

Kang   Wenbin

Wang   Jiangxin

Zhu   Bowen

Chen   Geng

Gu   Peiyang

Huanli   Dong

Gih ‐ Keong   LAU

Wang   Zilong

Hui   Yang

Pan   Shaowu

Yaqing   Liu

Xiaotian   Wang

Zhiyuan   Liu

Lokesh   Dhakar


Nguyen   Anh   Chien

Rohit   Abraham   John


Yeo   Joo   Chuan

Dihan   Md.

  Nuruddin   Hasan

Qi   Dianpeng

Qi   Dianpeng

Jiahui   Wang

Sanghoon   Lee

Tran   Van   Thai



Poster   Title

Flexible   Carbon   Nanotubes   based   actuators

Synthesis,   Structure   and   Properties   of   Functionalized   Large   N ‐ heteroacenes

Flexible   Electrochromo ‐ Supercapacitor   Based   on   Highly   Stable   Transparent   Conductive   Silver   Grid/PEDO

Foldable   Electrochromics   Enabled   by   Nanopaper   Transfer   Method

Highly   Stretchable   and   Self ‐ Deformable   Alternating   Current   Electroluminescent   Devices

Skin ‐ inspired   Haptic   Memory   Arrays   with   Electrically   Reconfigurable   Architecture

Configurable   Resistive   Switching   for   Protein ‐ Based   Devices

Solution ‐ Processable   Thiadiazoloquinoxaline ‐ Based   Donor–Acceptor   Small   Molecules   for   Thin ‐ Film   Trans

Solution ‐ Processed   Large ‐ Area   Nanocrystal   Arrays   of   Metal–Organic   Frameworks   as   Wearable,   Ultrasensitive,

Compliant   electrodes   with   tunable   transmittance   using    microscopically   crumpled   indium   tin   oxides

Fully ‐ Characterized   Pyrene ‐ Fused   Octaazadecacene   and   Tetraazaoctacene   Synthesis,   Structure   and   Prope

Self ‐ protection   of   Electrochemical   Storage   Devices   via   a   Thermal   Reversible   Sol ‐ gel   Transition

Flexible   Energy   Textiles

Alcohol   mediated   resistance   switching   device   based   on   metal ‐ organic   frameworks

Engineering   Photo ‐ Electrochemical   (PEC)   Hydrogen   Evolution   Based   on   Programmable   Nanobamboo   Array

Thickness ‐ gradient   Films   for   High   Gauge ‐ factor   Stretchable   Strain   Sensors

Flexible   Motion   Sensor   Integrated   With   Triboelectric   Nanogenerator   for   Wearable   Device   Applications

Flexible   and   Stretchable   devices   based   on   Dielectric   elastomers

Flexible   and   Stretchable   Display   Devices   based   on   Electro ‐ deposition   of   Nanomaterials

Photochemical   Activation   For   Low   Temperature   Solution   Based   Transparent   and   Flexible   Electronics

Liquid ‐ State   Flexible   Microfluidic   Tactile   Sensor

Triple ‐ State   Tactile   Sensing   Device   with   High   Flexibility,   Durability,   and   Sensitivity

Flexible   Fabry ‐ Perot   filters   based   on   terahertz   metamaterial   reflectors   for   curvature   sensing

Highly   Stretchable   Gold   Nanobelts   with   Sinusoidal   Structures   for   Recording   Electrocorticogram

Highly   Stretchable   Micro ‐ supercapacitors   Based   on   Out ‐ of   Plane   Wavy   Graphene   Micro ‐ ribbons

Flexible   multi ‐ channel   muscle   electrode   for   functional   electrical   stimulation

Selective   recording   and   stimulation   on   peripheral   nerves   using   flexible   sling   electrodes

Inkjet ‐ printed   Ag   microelectrodes   for   flexible   proximity   capacitance   sensor

A   Multifunctional   Electronic   Skin

The   Internet   of   Everything   Wearable   Breast   Cancer   Screening   iTBra   System:   Empowering   Early   Detection


Flexible Carbon Nanotubes Based Actuators

Ela Sachyani 1 , Michael Layani 1,2 and Shlomo Magdassi 1

1 Institute of Chemistry, The Hebrew University of Jerusalem, Israel


School of Materials Science and Engineering, Nanyang Technological University,


Actuators are devices that respond by movement to a given trigger, such as electric and magnetic fields, heat or light. Each trigger involves a different mechanism for the actuation process. Actuators can be used in a variety of fields, such as mechanical devices, sensing, and soft robotics.

The work presented here is focused on printed electrothermal carbon nanotubes

(CNTs) based actuators. A typical actuator is composed of a double layer, containing

CNT electrode and a polymer. CNTs are electrically conductive, thermally conductive and flexible, and therefore are excellent candidates for flexible and stretchable electrothermally triggered actuators.

Three main types of CNT based actuators will be presented. The first type is a Ushaped CNT layer deposited on top of polyimide substrate. The actuation occurred due to the difference in coefficient of thermal expansion (CTE) between the two materials.

When voltage is applied, the CNT layer heats up and the double layered actuator bends towards the material that has smaller CTE. The second type is a CNT layer deposited on a Shape Memory Polymer (SMP) [1]. The SMP is a material that can recover its permanent shape after temporary shape deformation. Here, the CNT serves as an electrical heater that reverts the SMP back to its original state. The third type of CNT based actuator is a combination of the first and second type of actuators.

The future goal is to fabricate 3D printed actuators for soft robotic applications.

[1] Zarek, M.; Layani, M.; Cooperstein, I.; Sachyani, E.; Cohn, D.; Magdassi, S. “3D

Printing of Shape Memory Polymers for Flexible Electronic Devices” Advanced

Materials 2015 .


Synthesis, Structure and Properties of Functionalized Large



Zhang Jing 1 and Zhang Qichun 1,2

1 School of Materials Science and Engineering, Nanyang Technological University

Singapore, 639798, Singapore

2 School of Physical and Mathematical Sciences, Nanyang Technological


Singapore 637371, Singapore

Recently, large N-heteroacenes have been proven to be charming ambipolar or n-type semiconducting materials. A series of N-heteroacenes have been explored and high electron mobility under vacuum or inert atmosphere was achieved, but it is still challenging to find a suitable N-heteroacene with good air-stable performance. To our knowledge, lowering the LUMO level of materials is the most effective way to prevent electron trapping by O


or H


O and realize high electron transport in air. To achieve this, introducing more electron-withdrawing sp


N atoms into the backbone of Nheteroacenes and/or building up large conjugated systems have been strongly investigated. Unfortunately, these compounds have very poor stability and could be quickly degraded either by moisture, oxygen, or Diels−Alder reactions. Given these factors, we are interested in preparing a stable large N-heteroquinone 6,10,17,21-tetra-



OANQ ) with eight sp


N atoms doped in the backbone.

A large π-conjugated N-heteroquinone, OANQ, has been successfully synthesized and characterized. The as-prepared OANQ displays a particularly low LUMO level and good environmental stability. The existence of a slight twist on the backbone was believed to contribute strongly in stabilizing the molecular packing. The single crystal

FETs of OANQ showed electron-transporting mobility up to 0.2 cm



-1 s


under ambient condition and maintained good performance stability. Our initial results suggest that the design of large π-conjugated N-heteroquinones could be a promising way to develop new air-stable n-type materials and devices.

An unexpected “kinked” N-heteroacene with the slipped two-dimensional ladder-like packing feature is produced from the conventional condensation reaction. The asobtained compound [2,2’]bi(5,12-bis(TIPS)piperazin-3-one[2,3-b]phenazine) (2BPP) consists of two identical backbones (5,12-bis(TIPS)piperazin-3-one[2,3-b]phenazine), which are fused together through a C=C double bond and two intramolecular H-bonds.

The study on charge carrier transport indicates that 2BPP single crystal has a hole mobility up to 0.3 cm 2 V




, while theoretical calculation suggests that this compound possesses potential well-balanced ambipolar charge-transport characteristics.

[1] Wang, C.; Zhang, J.; Long, G.; Aratani, N.; Yamada, H.; Zhao, Y.; Zhang, Q.

“Synthesis, Structure and Air-stable N-type Field-Effect Transistor Behaviors of

Functionalized Octaazanonacene-8,19-dione,” Angew. Chem. Int. Ed., 2015 , 54,


[2] Zhang, J.; Wang, C.; Long, G.; Aratani, N.; Yamada, H.; Zhang, Q. “Fusing Nheteroacene Analogues into One Molecule with Slipped Two-dimensional Ladderlike Packing,’’

Chem. Sci., under revision.


Flexible Electrochromo-Supercapacitor based on Highly Stable

Transparent Conductive Silver Grid/PEDOT:PSS Electrodes

Guofa Cai and Pooi See Lee *

School of Materials Science and Engineering, Nanyang Technological University,


Corresponding Author


Silver grids are attractive for replacing indium tin oxide as flexible transparent conductors. This work aims to tackle the looming concern of electrochemical stability of silver based transparent conductors. The silver grid/PEDOT:PSS hybrid film with high conductivity and excellent stability has been successfully fabricated. We demonstrate its functionality for flexible electrochromic applications by coating one layer of WO


nanoparticles on the silver grid/PEDOT:PSS hybrid film. It presents a large optical modulation of 81.9% at 633 nm, fast switching and high coloration efficiency (124.5 cm 2 C



More importantly, excellent electrochemical cycling stability (sustaining 79.1% of their initial transmittance modulation after 1,000 cycles) and remarkable mechanical flexibility (optical modulation decays 7.5% after compressive bending 1,200 cycles) were achieved. We present a novel smart supercapacitor, which functions as a regular energy storage device and simultaneously monitors the energy level stored by rapid and reversible color variation even at high current charge/discharge conditions. The film sustains an optical modulation of 87.7% and a specific capacitance of 67.2% at 10 A g


compared with their initial value at current density of 1 A g


, respectively. The high-performance silver grid/PEDOT:PSS hybrid transparent films exhibit promising features for various emerging flexible electronics and optoelectronics device.


Foldable Electrochromics Enabled by Nanopaper Transfer Method

Wenbin Kang, Chaoyi Yan, Ce Yao Foo and Pooi See Lee*

School of Materials Science and Engineering

50 Nanyang Avenue, 639798, Singapore


Deformable electronics based on novel substrates and conducting materials are now being highly pursued to cater for the stringent requirement to realize next-generation electronics. A rising concept of adopting nanocellulose has recently stirred great excitement due to its compelling advantages, like ubiquitous abundance, biocompatibility, strong mechanical strength, great flexibiltiy and fascinating surface properties over traditional petroleum based plastics such as polyethylene terephthalate

(PET), polyimide (PI) and polycarbonate (PC).

Utilizing the aforementioned properties, we developed a nanopaper transfer technique for transparent conductive electrodes with Ag nanowires with high figure of merit [1]. The nanopaper electrodes are highly conducting and competitive to commercial ITO/glass. Besides, the Ag nanowires are well-adhered to the nanopaper surface maintaining high conductivity after folding (Figure 1a and b). Finally, a foldable electrochromic nanopaper based on this novel electrode is demonstrated. WO

3 as the electrochrome is electrochemically deposited on the electrode. The electrochromic nanopaper shows good optical modulation stability against repeated folding (Figure 1c and d).

In conclusion, the nanopaper transfer method as well as foldable electrochromism holds great promise for the development of next-generation deformable electronic devices.

Figure 1. FESEM images of the nanopaper electrode folded to a) -180° and b) +180°;

Influence of folding cycles on c) contrast and d) switching rate.

[1] W. Kang; C. Yan; C. Y. Foo; P. S. Lee. “Foldable Electrochromics Enabled by

Nanopaper Transfer Method,”

Adv. Funct. Mater.

, 2015 , 25 , 4203-4210


Highly Stretchable and Active Deformable Alternating Current

Electroluminescent Devices

Jiangxin Wang 1 , Chaoyi Yan 1 , Kenji Jianzhi Chee 1,2 and Pooi See Lee 1,2*

1 School of Materials Science and Engineering, 50 Nanyang Avenue,

Nanyang Technological University, Singapore, 639798

2 Institute of Sports Research, Nanyang Technological University, Singapore 639798


Electroluminescent (EL) devices with good mechanical compliance can benefit and inspire a plethora of new applications, such as deformable and wearable displays, visual readout on artificial skins, biomedical imaging and monitoring devices, etc . Stretchable

EL devices have been demonstrated either by employing intrinsically stretchable materials or stretchable device structures. Challenges in intrinsically stretchable devices persist in that their emission intensity significantly reduces under stretching strains and the devices could not survive large strain cycles, while the devices employing stretchable structures encounter the difficulties of complicated fabrication procedures and unstretchable emissive components. Furthermore, all these pioneering work were geared towards maintaining device functionality when they were passively deformed by external forces.

In this work [1], we develop a novel approach to fabricate intrinsically stretchable inorganic light-emitting devices with sustained functionality under stretching strains and excellent stability under large strain cycles. The stretchable and transparent electrodes were fabricated with silver nanowire (AgNW) networks embedded in a polydimethylsiloxane (PDMS) matrix. The light-emitting layer was made of an inorganic material of ZnS:Cu with imparted stretchability by the elastomer matrix. The resultant device exhibited high stretchability, withstanding strain up to 100% with good cycling stability at 80% stretching strain. The good mechanical property of the devices is competitive to the stretchable polymer light-emitting devices, while advantages of inorganic materials, i.e., long life-time and fast response time, might exceed their organic counterparts. Taking full advantage of the simple device fabrication procedure, we demonstrate that the stretchable EL devices could be driven to dynamic shapes upon integration with dielectric elastomer actuators (DEAs). Compared to conventional stretchable EL devices, the actively deformable EL device offers the special feature of dynamic shape display. The fabrication procedure and devices developed in this report will meet wide applications in light-weight and miniaturized EL elements for volumetric display and other applications.

[1] Wang, J.; Yan, C.; Chee, K. J.; Lee, P. S. “Highly Stretchable and Self-Deformable

Alternating Current Electroluminescent Devices,” Adv. Mater. 2015 , 27 , 2876–



Skin-inspired Haptic Memory Arrays with Electrically

Reconfigurable Architecture

Bowen Zhu, Yaqing Liu, Geng Chen and Xiaodong Chen *

School of Materials Science and Engineering, Nanyang Technological University,

50 Nanyang Avenue, Singapore 639798

The human skin contains a variety of sensory receptors which respond to external stimuli and transmit sensation information to the brain through afferent nerves to form sensory memory, allowing humans to perceive the sensations, so as to recognize the surrounding environment and conduct daily activities. The exquisite sensations and tactile afferents of the skin inspire us to the emergence of sensory memory devices that not only emulate the tactile sensation of natural skin, but retain the sensory information after external stimuli vanishes. In this work, a skin-inspired haptic memory array, which can be electrically programmed from high resistance state to low resistance state by the application of external pressure, is achieved through the rational integration of resistive switching memory devices with resistive pressure sensors to mimic the sensory memory of human (Figure 1). The haptic memory device arrays not only demonstrate high sensitivity in the low pressure regime in accordance with tactile sensing, but can retain the pressure information after the removal of external pressure for more than a week by virtue of the nonvolatile nature of the memory devices. The rise of haptic memory devices would allow for the mimicry of human sensory memory, opening new avenues for designing next-generation sensing systems for applications in electronic skins, humanoid robots and human-machine interfaces.

Figure 1. Haptic memory arrays for the mimicry of human sensory memory


Johansson, R. S.; Flanagan, J. R. “Coding and Use of Tactile Signals from The

Fingertips in Object Manipulation Tasks,”

Nat. Rev. Neurosci.

2009 , 10 , 345-359.

[2] Zhu, B.; Wang, H.; Liu, Y.; Qi, D.; Liu, Z.; Wang, H.; Yu, J.; Sherburne, M.;

Wang, Z.; Chen, X. “Skin-inspired Haptic Memory Arrays with Electrically

Reconfigurable Architecture”

Adv. Mater.

2015 , 27 , adma.201504754.


Configurable Resistive Switching for Protein-Based Devices

Geng Chen, Hong Wang, Bowen Zhu and Xiaodong Chen*

School of Materials Science and Engineering, Nanyang Technological University,

50 Nanyang Avenue, Singapore 639798

The employment of natural biomaterials as the basic building blocks of electronic devices is of growing interest for biocompatible and green electronics. In this work, resistive switching (RS) devices based on natural silk proteins with configurable functionality are demonstrated. The RS devices can be effectively and specifically controlled by controlling the compliance current in the set process. Memory RS can be triggered by a higher compliance current, while threshold RS can be triggered by a lower compliance current. Furthermore, two types of memory devices, working in random access and WORM modes, can be achieved with the RS effect. The results suggest that silk proteins possess the potential for sustainable electronics and data storage. In addition, this finding would provide important guidelines for the performance optimization of biomaterials based memory devices and the study of the underlying mechanism behind the RS effect arising from biomaterials.

H. Wang; Y. Du; Y. Li; B. Zhu; W. R. Leow; Y. Li; et al. "Configurable

Resistive Switching between Memory and Threshold Characteristics for

Protein-Based Devices,", Adv. Func. Mater.

, 2015 , 25 , 3825-3831.

Wang, H.; Meng, F.; Zhu, B.; Leow, W. R.; Liu, Y.; Chen, X.* "Resistive

Switching Memory Devices Based on Protein", Adv. Mater.

2015 , 27 , doi:


Zhu, B.; Wang, H.; Leow, W. R.; Cai, Y.; Loh, X. J.; Han, M.-Y.; Chen, X.*

"Silk Fibroin for Flexible Electronic Devices", Adv. Mater.

2015 , 27 , doi:10.1002/adma.201504276.


Solution-Processable Thiadiazoloquinoxaline-Based Donor–Acceptor

Small Molecules for Thin-Film Transistors

Gu Peiyang


, Zhang Jing


and Zhang Qichun



School of Materials Science and Engineering, Nanyang Technological University

Singapore, 639798, Singapore


School of Physical and Mathematical Sciences, Nanyang Technological


Singapore 637371, Singapore

Although many [1,2,5]thiadiazolo[3,4g ]quinoxaline (TQ)-containing polymers, incorporated with thiophene derivatives, were applied in organic field-effect transistors

(OFETs), charge carrier mobility in conjugated low band gap donor (D)-acceptor (A) small molecules has been rarely reported to date. To enrich the TQ-containing small molecular family, three TQ derivatives, 10,14-bis(5-(2-ethylhexyl)thiophen-2yl)dibenzo[ a , c ][1,2,5]thiadiazolo[3,4i ]phenazine ( 1 ), 10,14-bis(5-(2ethylhexyl)thiophen-2-yl)phenanthro[4,5abc ][1,2,5]thiadiazolo[3,4i ]phenazine ( 2 ), and 2,7-di-tert-butyl-10,14-bis(5-(2-ethylhexyl)thiophen-2-yl)phenanthro[4,5abc ][1,2,5]thiadiazolo[3,4i ]phenazine ( 3 ), with a thiophene unit attached onto the TQ cores (fused by phenanthrene, pyrene, and 2,7-di-tert-butylpyrene groups), were designed and synthesized. The optoelectronic and OFET properties of compounds 1 3 are affected through changing the fused aromatic unit in the TQ core or the side chains.

The thin-film transistors for compounds 1 3 show typical p-type performance with mobility as high as 0.012, 0.05 and 0.0055 cm






and on/off current ratios of 3×10





and 1×10


under optimized conditions, respectively. Due to the steric effect of the extra bulk group, compound 3 adopts a looser packing with larger π-π distance, which subsequently reduces the transport property. Our results suggest that the D-A πconjugated small molecules could be good candidates for application in organic electronics.

Steckler, T. T.; Henriksson, P.; Mollinger, S.; Lundin, A.; Salleo, A.;

Andersson, M. R. “Very Low Band Gap Thiadiazoloquinoxaline Donor-

Acceptor Polymers as Multi-tool Conjugated Polymers,” J. Am. Chem. Soc.

2014, 136, 1190-1193.

Dallos, T.; Beckmann, D.; Brunklaus, G.; Baumgarten, M.

“Thiadiazoloquinoxaline-Acetylene Containing Polymers as Semiconductors in

Ambipolar Field Effect Transistors,”

J. Am. Chem. Soc.

2011, 133, 13898-



Solution-Processed Large-Area Nanocrystal Arrays of Metal–

Organic Frameworks as Wearable, Ultrasensitive, Electronic Skin for Health Monitoring

Xiaolong Fu, Huanli Dong, Yonggang Zhen and Wenping Hu*

Beijing National Laboratory for Molecular Sciences

Key Laboratory of Organic Solids, Institute of Chemistry,

Chinese Academy of Sciences

Electronic skin has attracted much research interest for applications in medical diagnostics, artificial intelligence, and bio-implant devices in recent years [1-4]. To date, multiple kinds of active materials (carbon nanotubes, metal nanoparticles, inorganic nanowires, organic semiconductors, textile fabrics, etc.

) have been introduced into pressure sensor configurations to construct electronic skins [1-4].

However, it still remains a challenge to achieve highly sensitive and large area pressure sensor arrays for electronic skin based on easy-processing active materials with facile fabrication method and simple device structures.

Metal-organic frameworks (MOFs) are crystalline materials consisting metal ions and organic ligands. Conducting MOFs could have potential applications in reconfigurable electronic devices. Copper 7,7,8,8-tetracyanop-quinodimethane

(CuTCNQ) is a conducting MOF, and has attracted long attention since its discovery in

1979 [5-6]. Herein, for the first time, we report that conducting MOFs nanocrystal arrays could be used for ultrasensitive electronic skins, which could be fabricated in large area through solution process facilely and cost-effectively. The electronic skin showed very high sensitivity (6.25 kPa


), fast response time (<10 ms), low detection limit (0.73 Pa), low working voltage (1V), low power consumption (<0.1 mW), and high stability (>10,000 times). Furthermore, the electronic skin demonstrated promising biomedical applications as flexible and wearable devices in monitoring biological signals, such as radial artery waveforms in real time, clearly suggesting the prospect of the electronic skin in disease prevention and medical diagnosis [7].

[1] D. J. Lipomi, M. Vosgueritchian, B. C. K. Tee, S. L. Hellstrom, J. A. Lee , C. H.

Fox , Z. Bao, Nat. Nanotechnol . 2011 , 6 , 788-792.

[2] W. Wu, X. Wen, Z. L. Wang, Science 2013 , 340 , 952-957.

[3] Y. Zang, F. Zhang, D. Huang, X. Gao, C. Di, D. Zhu, Nat. Commun . 2015 , 6 , 6269.

[4] L. Viry, A. Levi, M. Totaro, A. Mondini, V. Mattoli, B. Mazzolai L. Beccai, Adv.

Mater. 2014 , 26 , 2659-2664.

[5] Y. Liu, Z. Ji, Q. Tang, L. Jiang, H. Li, M. He, W. Hu, D. Zhang, L. Jiang, X. Wang,

C. Wang, Y. Liu, D. Zhu, Adv. Mater.

2005 , 17 , 2953-2957.

[6] Y. Liu, H. Li, D. Tu, Z. Ji, C. Wang, Q. Tang, M. Liu, W. Hu, Y. Liu, D Zhu, J.

Am. Chem. Soc.

2006 , 128 , 12917-12922.

[7] X. Fu, H. Dong, Y. Zhen, W. Hu, Small 2015 , 11 , 3351-3356.


Compliant Electrodes with Tunable Transmittance using

Microscopically Crumpled Indium-Tin-Oxide Thin Films

Gih-Keong Lau 1* , Hui-Yng Ong 1,2 , Milan Shrestha 1 and Thanh-Giang La 1

1 School of Mechanical and Aerospace Engineering,

Nanyang Technological University, Singapore 639798

2 School of Engineering, Nanyang Polytechnic, Singapore 569830

Indium-tin-oxide (ITO) thin films are perceived to be stiff and brittle. This work reports that crumpled ITO thin films on adhesive poly-acrylate dielectric elastomer can make compliant electrodes, sustaining compression of up to 25% × 25% equi-biaxial strain and unfolding. Its optical transmittance reduces with crumpling, but is subsequently restored with unfolding. A dielectric elastomer actuator (DEA) using the

14.2% × 14.2% initially crumpled ITO thin-film electrodes is electrically activated to produce a 37% areal strain. Such electric unfolding turns the translucent DEA to be transparent, with transmittance increased from 39.14% to 52.08%. This transmittance tunabilty promises to realize a low-cost smart privacy window.

Figure 1 shows the fabrication process to induce wrinkling or micro-folds on the surface of poly-acrylate elastomer (VHB 4905). First, a membrane of poly-acrylate elastomer was pre-stretched equi-biaxially. Secondly, the pre-stretched elastomer membrane is coated with 50 nm thick ITO thin film by electron beam evaporation method. The thermal expansion mismatch between the ITO film and the elastomer substrate induces mild wrinkles to the ITO coating at an electrode diameter D


. Thirdly, the ITO-coated elastomer membrane is relaxed from the initially high pre-stretch to a smaller one using a mechanical radial stretcher. Relaxation of the pre-stretched elastomer substrate yields a smaller electrode diameter. Surprisingly, bi-axial compression of up to 25% strain does not cause an observable crack in the wrinkled

ITO coating. This crack-free ITO thin film can undergo cycles of folding and unfolding, while remaining electrically conducting for electro-mechanical activation of dielectric elastomer actuators.



(i) Pre-stretch VHB






ITO as deposited on

VHB: c=0%

(ii) Deposit ITO thin film l




Compression at c=14.2%


E-beam evaporation of ITO

(iii) Mechanical crumpling


II l c=1-(D





Stretching at c=-5%

0% crumpling




25% crumpling


Figure 1: Crumpled ITO thin films: (a) crumpling steps; (b) tunable transmittance;

(c-d) SEM

Ong, H. Y., Shrestha, M., & Lau, G. K. (2015). “Microscopically crumpled indium-tinoxide thin films as compliant electrodes with tunable transmittance.” Appl. Phys. Lett.


107(13), 132902.


Fully-Characterized Pyrene-Fused Octaazadecacene and


Synthesis, Structure and Properties of Functionalized Large



Wang Zilong 1 and Zhang Qichun 1,2

1 School of Materials Science and Engineering,

Nanyang Technological University, Singapore, 639798, Singapore

2 School of Physical and Mathematical Sciences,

Nanyang Technological University, Singapore 637371, Singapore

Realizing large azaacenes is very important because of their great potential applications in organic electronics. In this report, we successfully synthesized and fully characterized two stable large azaacenes: octaazadecacene (OADA) and tetraazaoctacene (TAOA) through employing a relatively moderate aromatic unit, pyrene, as an embedded specie in the backbone of azaacene to ensure large conjugation and stability. The four TIPS groups of TAOA strongly hinder the π-π stacking due to the steric effect. With a longer conjugated azaacene core, OADA molecules adopt a face-to-face two-dimensional (2D) “bricklayer” arrangement. The interplanar distance range between 3.27 Å and 3.23 Å suggests the existence of strong π-π interactions, which are the main forces to stabilize the packing of OADA . The photoelectrochemical

(PEC) studies indicate that both azaacenes display n-type semiconductor behaviours.

Figure 1. Molecular structures of TAOA (A) and OADA (C), and their crystal stacking patterns (B) and (D), respectively.

Z Wang.; J Miao.; G Long.; P Gu.; J Li.; N Aratani.; H Yamada.; B Liu.; and Q

Zhang. “Fully-Characterized Pyrene-Fused Octaazadecacene and Tetraazaoctacene

Synthesis, Structure and Properties of Functionalized Large N -heteroacenes” Chem.

Sci, submitted.


Self-Protection of Electrochemical Storage Devices via a Thermal

Reversible Sol-Gel Transition

Hui Yang and Xiaodong Chen*

School of Materials Science and Engineering, Nanyang Technological University,

50 Nanyang Avenue, 639798, Singapore

Smart management of the thermal runaway of advanced electrochemical storage devices, such as lithium-ion batteries and supercapacitors, is a critical issue for the safe usage of such devices. These devices generate a lot of heat due to their high power delivery and fast current flow, which does not dissipate quickly, especially in the ultrafast charging and discharging processes, leading to risks of fire or explosion

[1]. Hence, good control of the thermal runaway is of prime importance. The techniques currently used to prevent thermal runaway are of two types. However, these techniques are passive strategies. There is no provision for the device to vary the charge-discharge rate according to temperature and resume original electrochemical performance once it is cooled to room temperature. Therefore, a smart and active thermal runaway control for electrochemical storage devices was designed through a reversible sol-gel transition of the electrolyte (Figure 1). Notably, the sol-gel process endows these devices with dynamic performance under different temperature, leading to active control of the thermal runaway, unlike the invariable charge and discharge rate of traditional supercapacitor using polymer gel or solid-state electrolytes.

Additionally, the reversibility of the sol-gel process also endows these devices with reusable thermal protection. This strategy shows tremendous promise for safe and controlled power delivery, and can be directly employed for designing electrochemical storage devices with inherent intelligent thermal management.

Figure 1. Illustration of sol-gel transition of electrolyte that slows the migration of conductive ions between the electrodes. Upon increasing the temperature, electrolyte solution transforms to hydrogels through hydrophobic association.

[1] Feng, X.; Sun, J.; Ouyang, M.; Wang, F.; He, X.; Lu, L.; Peng, H.

“Characterization of Penetration Induced Thermal Runaway Propagation Process within a Large Format Lithium Ion Battery Module,”

J. Power Sources 2015 , 275,



Flexible Energy Textiles

Shaowu Pan 1,2 , Jue Deng 1 and Huisheng Peng 1*

1 Laboratory of Advanced Materials, Fudan University, Shanghai, China


School of Materials Science and Engineering, Nanyang Technological University,


Portable energy devices are arousing enormous interest due to their flexible and wearable ability [1]. Herein, a new and general method to produce flexible, wearable dye-sensitized solar cell (DSC) and supercapacitor textiles by the stacking of two textile electrodes have been developed [2, 3]. Furthermore, a self-powering energy textile was obtained by integrating the DSC with supercapacitor textile. For the DSC textile, a metal-textile electrode that was made from micrometer-sized metal wires was used as a working electrode, while the textile counter electrode was woven from highly aligned carbon nanotube (CNT) fibers with high mechanical strength and electrical conductivity.

The resulting DSC textile exhibited a high energy conversion efficiency which was well maintained under bending.

This lightweight and wearable stacked DSC textile is superior to conventional planar DSCs because the energy conversion efficiency of the stacked DSC textile was independent of the angle of incident light.

For the supercapacitor textile, polyaniline (PANI) was introduced into CNT fiber textile which provides high electrochemical activity. The supercapacitor textile displays stable specific capacitance up to 272 F g -1

that can be well maintained after bending. When the DSC textile was assembled with supercapacitor textile to form integrated energy textile mimicking multilayered clothes (Figure 1), a high entire energy conversion and storage efficiency of 2.1% was achieved.

Figure 1. a) Photograph of multilayered clothes. b) Schematic illustration of the integrated energy textile. The enlarged view shows the working mechanism. SC refers to supercapacitor.


Chen, T.; Qiu, L.; Yang, Z.; Peng, H. “Novel Solar Cells in a Wire Format”,


Soc. Rev.

2013 , 42 , 5031-5041.

[2] Pan, S.; Yang, Z.; Chen, P.; Deng, J.; Li, H.; Peng, H. “Wearable Solar Cells by

Stacking Textile Electrodes”,

Angew. Chem. Int. Ed.

2014 , 53 , 6110-6114.


Pan, S.; Lin, H.; Deng, J; Chen, P.; Chen, X.; Yang, Z.; Peng, H. “Novel Wearable

Energy Devices Based on Aligned Carbon Nanotube Fiber Textiles”, Adv. Energy


2015 , 5 , 1401438.


Alcohol Mediated Resistance Switching Device based on

Metal Organic Frameworks

Yaqing Liu


, Hong Wang


, Wenxiong Shi


Zhiyuan Liu 1 , Shuzhou Li 1

, Weina Zhang


, Jiancan Yu


, Bowen Zhu

, Fengwei Huo 2* and Xiaodong Chen 1*



1 School of Materials Science and Engineering, Nanyang Technological University


Key Laboratory of Flexible Electronics,

Institute of Advanced Materials, Nanjing Tech University

The learning, memory and information storage systems in the human brain are chemically mediated processes, which are regulated by chemical molecules and ions.

For artificial information storage systems, resistance switching devices usually perform the memory function with the repeatable resistance switching effect triggered by an electrical stimulus. Till now, several memory devices with controllable resistance switching behavior had been explored, but the memory properties of these devices are mainly controlled by external physical operating parameters, such as light, magnetic field, or temperature. The main challenge in the realization of chemically mediated properties in electrical memory devices, whereby the relative performance of the device could be tuned by small molecules via host guest interactions, is to overcome the gap between chemical information and memory property.

Herein, we report alcohol mediated memory devices based on metal organic framework (MOF) films with reliable resistance switching property, where the resistance state is controlled by applying alcohol vapours to achieve multilevel information storage. This responsive electrical property relies on the ordered packing mode and the hydrogen bonding system of the guest molecules adsorbed on MOF crystals. Moreover, the MOF based memory devices can be fabricated on soft substrates to realize a flexible and chemically responsive memory device, showing potential applications in wearable information storage systems.


Engineering Photo-Electrochemical (PEC) Hydrogen Evolution

Based on Programmable Nanobamboo Array

Xiaotian Wang, Shuzhou Li* and Xiaodong Chen*

School of Materials Science and Engineering, Nanyang Technological University,

50 Nanyang Avenue, 639798, Singapore

Engineering interfacial photo-induced charge transfer for highly synergistic photocatalysis is successfully realized based on nanobamboo array architecture.

Programmable assemblies of various components and heterogeneous interfaces, and in turn, engineering of the energy band structure along the charge transport pathways, play a critical role in generating excellent synergistic effects of multiple components for promoting photocatalytic efficiency.

Figure 1. Schematic diagram of engineering interfacial charge transfer based on multicomponent nanobamboo array architecture.

Wang, X.; Liow, C.; Bisht, A.; Liu X.; Sum, T. C.;* Chen, X.;* Li, S.* "Engineering

Interfacial Photo-induced Charge Transfer Based on Nanobamboo Array Architecture for Efficient Solar-to-Chemical Energy Conversion" Adv. Mater.

2015, 27, 2207-


Wang, X.; Liow, C.; Qi, D.; Zhu, B.; Leow, W. R.; Wang, H.; Xue, C.; Chen, X.;* Li,

S.*"Programmable Photoelectrochemical Hydrogen Evolution Based on Multisegmented CdS-Au Nanorod Arrays " Adv. Mater.

2014, 26, 3506-3512.


Thickness-Gradient Films for High Gauge-Factor Stretchable Strain


Zhiyuan Liu, Dianpeng Qi and Xiaodong Chen *

School of Materials Science and Engineering, Nanyang Technological University,

50 Nanyang Avenue, 639798, Singapore

Stretchable strain sensors are vital for the emergence of soft electronics, including wearable and implantable devices, human-like robots with artificial skins, and bionic sensory systems. Particularly, the gauge factor, reflecting the sensitivity, is vital for detecting micro-strain. High gauge-factor sensors can largely improve the threshold detection level, thus opening up the field for exploration of subtle strain phenomena.

Several kinds of stretchable strain sensors were fabricated before, however, it remains a challenge to couple large stretchability with high sensitivity, because large stretchability demands that the material remains structurally and morphologically intact under large strain, while high sensitivity requires substantial structural changes even under small strain.

In this work, for the first time, we propose a new strategy by constructing the film with gradient thickness, which couples the seemingly contrary properties of brittleness and stretchability together to fabricate strain sensors with high gauge-factor and high stretchability. The thickness-gradient film was formed by employing self-pinning effect of the single wall carbon nanotube solution. The fabricated sensor possesses surprisingly good performance covering all requirements of sensitivity, stretchability and long-term stability. Finally, weak sound detection taking advantage of the highly improved gauge-factor is demonstrated and the detailed damping vibration modes are recognized. This study proposes a new strategy to highly improve the sensitivity and stretchability of the strain sensor. The fabricated high-performance sensor takes a solid step towards real application in soft electronics.

Figure 1. Diagram of the formation process of thickness-gradient films and weak sound detection by utilizing the high gauge-factor.


Flexible Motion Sensor Integrated with Triboelectric Nanogenerator for Wearable Device Applications

Lokesh Dhakar 1,2 , Prakash Pitchappa 1 , F. E. H. Tay 2,3 and Chengkuo Lee 1*

1 Department of Electrical and Computer Engineering,

National University of Singapore, 4 Engineering Drive 3, Singapore 117576

2 NUS Graduate School for Integrative Sciences and Engineering,

28 Medical Drive, Singapore 117456


Department of Mechanical Engineering,

National University of Singapore, 9 Engineering Drive 1, Singapore 117576

Human motion sensing plays an important role in various applications, including gesture recognition, human-computer interfacing, rehabilitation and patient monitoring

[1]. However, powering wearable sensors and devices is a huge challenge as batteries have a limited lifetime and are not environmentally friendly. In this work, we demonstrate a flexible and wearable sensor for the detection of human finger motion for static position and dynamic motion. The detection of the finger motion by the flexible sensor is based on the change in capacitance between the device electrode and human skin (epidermis), as the finger moves. The device is demonstrated to capture dynamic motion and static position based on the change in capacitance, as shown in

Figure 1a and b, respectively. It is also proposed that the device can utilize change in electric field by measuring the oscillating potential at electrode to sense the human finger movement. The same device configuration also serves as a triboelectric nanogenerator which can harvest mechanical energy from finger motion. It is shown to generate a maximum voltage of 70 V and a current area density of 2.7 μA/cm 2 at a load resistance of 5 MΩ (Figure 1c and d).

This work contributes towards development of self-powered sensors for human computer interfacing and patient monitoring applications.

[2] Yamada, T. et al. “A stretchable carbon nanotube strain sensor for human-motion detection,”

Nature Nanotech.

2011 , 6, 296-301.


Fan, F. R. et al. “Flexible triboelectric generator,”

Nano Energy 2012 , 1, 328-334.

Fig. 1


Flexible and Stretchable Devices based on Dielectric Elastomers



, Nguyen Anh Chien


and Nripan Mathews



School of Materials Science and Engineering, Nanyang Technological University,

Singapore 639798


Energy Research Institute @ NTU (ERI@N), Nanyang Technological University,

Singapore 637553


Electroactive polymers (EAPs) are of special interest to researchers for developing high performance actuator materials. Various types of polymers under the general category of EAP have been investigated, such as electrostrictive polymers, piezoelectric polymers, and dielectric elastomers and electrochemically actuated conductive polymers. Under all these categories, dielectric elastomers (DEs) deserve a special mention as they can generate strain of over 100%. Based on the principle of

Maxwell Stress, the performance depends on parameters like dielectric permittivity of material and electric field [1]. A dielectric elastomer layer is sandwiched between compliant electrodes and voltage is applied, giving rise to electrostatic forces which compress the dielectric layer and results in deformation [1]. This effect can be used in extension and compression, as desired for the application. We demonstrate here a possible mechanism for thickness-mode actuation of the top layer by utilizing a soft material placed on top of the active in-plane actuating region, which can be used to create programmable tactile displays on flexible substrates [1]. Furthermore, we can do conformable surface texture applications based on it. A novel application of this technology can be to create a tunable YES-NO gate for flow channels in PDMS-based microfluidic devices. Another potential application of the dielectric device can be for stretching of photonic crystals, which can be integrated with the DE device. We are trying to optimize the performance of the thickness mode DEs by improving on the dielectric and mechanical properties of the material [2].

[1] H. Prahlad, Ron Pelrine, Roy Kornbluh, Philip von Guggenberg, Surjit Chhokar &

Joseph Eckerle, Programmable Surface Deformation: Thickness-Mode Electroactive

Polymer Actuators and Their Applications, 2005, Proceedings of SPIE, 5759, 102-113.

[2] Ankit, Nguyen A. Chien, Nripan Mathews, “Optimizing the thickness-mode electroactive polymer actuators for tactile display application” (manuscript in preparation).


Flexible and Stretchable Display Devices based on Electro-deposition of Nanomaterials

Varun Rai


, Nguyen Anh Chien


, John Rohit Abraham


and Nripan Mathews



School of Materials Science and Engineering, Nanyang Technological University,

Singapore 639798

2 Energy Research Institute @ NTU (ERI@N), Nanyang Technological University,

Singapore 637553


Advancement in materials, technology, and processing allow development of high quality, flexible and stretchable electronic and optoelectronic devices to best complement and integrate into physical and biological systems. Nanomaterials are promising for developing flexible and stretchable display devices because of their unique electronic and optical properties that can be different from the corresponding bulk. Moreover, nanomaterial processing is another interesting area to be explored for development of useful and practical application devices. We demonstrate here the mechanism and functionality of a simple-structured display device based on electrodeposition of silver nanoparticles between two transparent conductive electrodes [1]. A wide range of colours (red, yellow, cyan) and variable reflectivity (mirror-like silver, full black) can be reversibly switched with respect to the original transparency. We have optimized the operating mechanism that allows display of multiple colors in a single device via the same electro-deposition reaction. Device switching kinetics between coloured and transparent states were also studied in relation to electrode surface modification and roles of electrochemical mediators [2]. With its simple structure and usage of versatile electrochemistry, we are in the process of applying this technology for fully flexible and stretchable applications. Several applications can be envisioned, ranging from conventional flexible displays to futuristic conformable surface interactive display and control.

[1] Shingo, A.; Kazuki, N.; Kanae, K.; Ayako T.; Norihisa, K. “Electrochemical

Optical-Modulation Device with Reversible Transformation between Transparent,

Mirror, and Black” Adv. Mater.

2012 , 24 , OP122–OP126.


Varun Rai, Nguyen A. Chien, Nripan Mathews, “Optimization of color formation and switching kinetics in nano-silver based electro-deposition process for display application” (manuscript in preparation).


Photochemical Activation for Low Temperature Solution Based

Transparent and Flexible Electronics

Rohit Abraham John 1 , Nguyen Anh Chien 1 and Nripan Mathews 1,2*


School of Materials Science and Engineering, Nanyang Technological University,

Singapore 637553


Energy Research Institute @ NTU (ERI@N), Nanyang Technological University,

Singapore 637553


Amorphous metal oxide semiconductors have made tremendous strides, particularly in display applications, in a relatively short time. This not only challenges silicon in conventional applications, but also opens doors to novel areas, like transparent and flexible electronics. These materials exhibit a desirous combination of high optical transparency, high electron mobility, large area uniformity, good process integration capabilities and compatibility with facile solution based processing techniques [1]. However, such techniques are usually followed by a post deposition high temperature annealing treatment to enhance the electronic performance and to bring it up to a level comparable with their vacuum deposited counterparts. This thermal treatment makes it incompatible with temperature intolerant flexible substrates. Here, we demonstrate UV exposure as an effective route to anneal these active layers at low temperatures (120 o

C). UV radiation provides sufficient energy to break the chemical bonds and facilitates thin film formation. Indium oxide transparent thin film transistors

(TFTs) were fabricated on ITO and FTO glass with saturation mobility (μ sat

) > 8 cm


/Vs, threshold voltage (V th

) around 0 V, sub-threshold swing < 1 V/dec, on-off ratio

> 10 5 [2]. This low temperature process could be easily transferred onto flexible substrates, like PET and PEN to demonstrate flexible circuits. This could serve as a platform for development of ubiquitous wearable camouflage electronics and sensors for artificial skin technology in the future.

[1] K. Nomura, H. Ohta, A. Takagi, T. Kamiya, M. Hirano, and H. Hosono, "Roomtemperature fabrication of transparent flexible thin-film transistors using amorphous oxide semiconductors," Nature , vol. 432, pp. 488-492, 11/25/print 2004.

[2] Rohit Abraham John, Nguyen Anh Chien, Nripan Mathews “DUV Activation of

Solution Processed Thin Film Circuits at Low Temperature” (manuscript in preparation).


Liquid-State Flexible Microfluidic Tactile Sensor



, Joo Chuan Yeo


and Chwee Teck Lim



NUS Graduate School for Integrative Sciences and Engineering,

National University of Singapore, Singapore 117456


Centre for Advanced 2D Materials and Graphene Research Centre,

National University of Singapore, Singapore 117546


Department of Biomedical Engineering, National University of Singapore, Singapore


4 Mechanobiology Institute, National University of Singapore, Singapore 117411


Both authors contributed equally to this work


Here, an advanced 2D nanomaterial nanosuspension liquid-based microfluidic tactile sensor is presented. This liquid-state sensing platform comprises graphene oxide

(GO) nanosuspension, which serves as the active detection element and an Ecoflex-

PDMS microfluidic assembly encapsulating the working fluid. The use of the highly resistive GO with low surface tension and non-corrosive characteristic renders the fabricated physical sensor highly sensitive and versatile. The resistive sensor exhibits distinctive features, such as superior thinness, high flexibility, large area conformability, and small physical size. In addition, it displays excellent mechanical deformability and is able to maintain the integrity of the liquid confinement within the microchannel after being subjected to various mechanical deformations. This wearable tactile sensor is also capable of distinguishing different user-applied mechanical forces, including pressing, stretching, and bending. Moreover, it is possible to identify hand muscle-induced motions, like finger flexing and fist clenching, using this tactile sensor, illustrating the potential of the flexible liquid-state sensing platform as a wearable diagnostic and prognostic device for real-time health monitoring.


Triple-State Tactile Sensing Device with High Flexibility, Durability and Sensitivity

Joo Chuan Yeo


, Kenry


and Chwee Teck Lim



NUS Graduate School for Integrative Sciences and Engineering,

National University of Singapore, Singapore 117456


Centre for Advanced 2D Materials and Graphene Research Centre,

National University of Singapore, Singapore 117546


Department of Biomedical Engineering, National University of Singapore, Singapore


4 Mechanobiology Institute, National University of Singapore, Singapore 117411


Both authors contributed equally to this work


Here, we develop a simple and robust triple-state liquid-based resistive microfluidic tactile sensor with high flexibility, durability and sensitivity. The device comprises a platinum-cured silicone microfluidic assembly filled with liquid metallic alloy interfacing two screen-printed conductive electrodes on a polyethylene terephthalate film. This deformable triple-state sensor is highly sensitive and able to differentiate compressive loads with an extremely large range of pressure and bending loads as well as distinct body movements. As proof-of-concept of the applicability of our tactile sensor, we demonstrate the measurements of localized dynamic foot pressure by embedding the device in shoes and high heels. Owing to its unique and durable structure, the sensor is capable of withstanding strenuous mechanical load applications without compromising its electrical signal stability and overall integrity. Overall, this work facilitates the realization of functional liquid-state device technology with superior mechanical flexibility and sensitivity.


Flexible Fabry-Perot Filters based on Terahertz Metamaterial

Reflectors for Curvature Sensing

Dihan Hasan, Prakash Pitchappa, Chong Pei Ho and Chengkuo Lee*

*Department of Electrical and Computer Engineering, National University of

Singapore, 4 Engineering Drive 3, 117576, Singapore

Curvature sensing enables a critical pathway for the determination of various crucial biomedical measurements, such as thickness of blood vessels and nerves, pulse rate, etc. In this report, we present a flexible Fabry-Perot (FP) filter using metamaterial as reflectors operating in the terahertz spectral region for curvature sensing application, as shown in Fig 1(a). The change in curvature causes the change in the cavity thickness and hence the filtered wavelength of the FP filters. Metamaterial based reflectors are used to ensure high reflection over a large spectral range and are relatively immune to tilt of the reflectors forming the cavity. The THz spectral region is utilized, owing to the lower energy of these electromagnetic waves.

The metamaterial reflector shows a high reflection profile with a dipolar resonance at 0.455 THz and minimal influence on varying curvature. When the air cavity, d, changes from 250 µm to 500 µm, the filtered frequency linearly red-shifts from 0.54

THz to 0.3 THz as shown in Fig 1(b). For curvature measurement, the device was rigidly mounted on a microvice holder to provide controlled out-of-plane deformation with desired curvature. The curvature is measured as bend height, ‘b’ relative to the flat surface. FP filter with d = 450 µm is used for curvature sensing experiments. The filter frequency for flat sample (b = 0 mm) was measured to be at 0.32 THz as d = 450 µm and at the largest curvature (b = 10 mm), d = 250 µm; the frequency was shift to ~0.55

THz as shown in Fig 1(c) - 1(e). The proposed device can also enable label free material detection by filling the fixed cavity with that material of refractive index. In conclusion, we have experimentally demonstrated the use of flexible metamaterial-based FP filters to achieve linear response over a wide curvature range, which could be potentially adopted in a wide range of bio-medical sensing applications.



Spacer (c) Reflector

(a) d = 450 µm

Reference flat surface d = 380 µm p

(d) FP filter d a

PET spacer

Reflector d = 250 µm b

Figure 1: (a) Schematic demonstration of curvature sensing with Fabry-Perot cavity and the inset shows two reflectors placed in parallel facing each other with a distance, d, and the unit cell definition of doughnut resonator used as metamaterial reflector.

Curvature Sensing – (b) shows the measured transmission spectra of FP filter at various bent height relative to the flat surface. The gradual reduction in the cavity thickness is shown using optical microscope image for (c) small curvature with d = 450 µm, (d) medium curvature with d = 380 µm and (e) large curvature with d = 250 µm, respectively.


Highly Stretchable Gold Nanobelts with Sinusoidal Structures for

Recording Electrocorticogram

Dianpeng Qi, Zhiyuan Liu, Yan Liu and Xiaodong Chen*

School of Materials Science and Engineering, Nanyang Technological University,

50 Nanyang Avenue, 639798, Singapore

Monitoring neural activity by external devices has attracted much attention due to its importance in gaining a deeper understanding of electrophysiological signals, enhancing the response of therapies, and promoting the establishment of humanmachine interfaces [1]. Neural electrodes, which connect the biological system with the outer machine, play a critical role in such neural signal monitoring process. However, the critical problem is that conventional electrodes are generally confronted with the mismatch between rigid/planar electrodes and soft/curvilinear tissues. In addition, the stretchable electrodes used in bio-monitoring for extended periods of time must have high stretchability and excellent stability for bio-integrated electronics and on-chip devices. In this study, encouraged by simulation results of the strain distribution in the conductive material and the advantages of employing wavy stretchable electrodes

(Figure 1), we rationally designed a unique out-of-plane tripod polydimethylsiloxane structure to achieve suspended gold nanobelts as stretchable electrodes. The resulting electrodes possess 130% stretchability and can be repeatedly stretched/relaxed (>

10,000 cycles) without significant increase of the belt resistance. As proof of concept, the as-prepared electrode was successfully used to record intracranial electroencephalogram or electrocorticogram (ECoG) signals from rats (Figure 1d).

Even more noteworthy is that both normal and pathologic ECoG signals from healthy and epilepsy rats, respectively, were successfully recorded and distinguished. This work would attract a broad readership, including readers from the fields of materials science, nanoscience, analytical chemistry and neuroscience.

Figure 1. Schematic drawing of different pre-stretched structures and the analysis of the relevant strain distribution by FEM method. (a) wrinkled structure, (b) suspending structure and (c) tripod PDMS bending structure, respectively. (d) Image of an electrode array on a rat brain and ECoG signals recorded.

[1] M. A. L. Nicolelis, D. Dimitrov, J. M. Carmena, R. Crist, G. Lehew, J. D.

Kralik, S. P. Wise, P. Natl. Acad. Sci. USA 2003 , 100, 11041.


Highly Stretchable Micro-supercapacitors based on Out-of-

Plane Wavy Graphene Micro-ribbons

Dianpeng Qi, Zhiyuan Liu, Yan Liu and Xiaodong Chen*

School of Materials Science and Engineering, Nanyang Technological University,

50 Nanyang Avenue, 639798, Singapore

Micro-supercapacitors (MSCs) with unique 2D structures are gaining attention due to their potential applications in miniature and flexible electronics [1]. Besides flexibility, stretchability of MSCs is also highly desired. This is because energy conversion and storage units ought to be capable of accommodating large strain while retaining the performance to match highly stretchable devices. Herein, we rationally designed a unique out-of-plane wavy structured electrode array for the first time (Figure

1). Based on such architecture, highly stretchable MSCs with stable electrochemical performance were created. The significant advantages of this configuration are that: -

(1) the out-of-plane wavy structures decrease the strain concentration on the electrode fingers in the stretching process, so as to prevent the electrode from cracking; (2) it ensures the electrode fingers are kept at a relative constant distance in the stretching process, so the stability of the MSCs could be further enhanced; (3) the MSCs could be stretched, which overcomes the limitation of the conventional stretchable MSC wherein only the interconnection conductor is stretchable, as the MSC itself is stiff. The performance of the as-prepared stretchable MSCs remains nearly unchanged when stretched under 100%. Even after it has been stretched and released over 5000 cycles, no significant decrease of the capacitance was observed. Finally, the highly stretchable

MSCs were successfully used to light a liquid crystal display, which demonstrates the application of stretchable MSCs for portable and wearable electronics.

Figure 1. Schematic drawing of the stretchable micro-supercapacitor and digital photo showing its use in powering a LCD under stretching

[1] J. Chmiola, C. Largeot, P. L. Taberna, P. Simon, Y. Gogotsi, Science 2010 ,



A Flexible Multi-channel Muscle Electrode for Functional Electrical

Stimulation with Reduced Muscle Fatigue

Jiahui Wang, Zhuolin Xiang, Shih-Cheng Yen and Chengkuo Lee

Singapore Institute for Neurotechnology (SINAPSE), National University of


Department of Electrical & Computer Engineering, National University of Singapore

Center for Sensors and MEMS, National University of Singapore

This paper reports a flexible multi-channel muscle electrode which allows

Functional Electrical Stimulation (FES) on muscle with less muscle fatigue induced.

FES is used for restoring muscle functions in people with disabilities. Flexible electrodes conformably attach onto the muscle surface and is implanted to control individual muscles precisely. To reduce muscle fatigue in traditional FES, this multichannel electrode activates different muscle fibers alternatively.

The polyimide muscle electrode (Figure 1) consists of a polyimide-Au-polyimide sandwiched structure, with openings on the polyimide for contact with muscle surface.

After being released from the substrate, it is then electroplated with IrOx.

Bench-tests, including cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) are done. Cyclic voltammograms show that IrOx has larger charge storage capacity (CSC) as compared to Au and Pt black, which meets the high current density requirement in muscle stimulation application. For EIS results, at 1 kHz which we are interested in for biomedical devices, IrOx also shows lower impedance, which reduces the voltage drop on the electrode itself.

In-vivo stimulation experiment is done on the muscle surface of biceps femoris of rats (Figure 2). Figure 3 shows the optimized electrode combination ((e2, e4), or (e3, e4), with distances 4000 μm and 5600 μm apart) and current (4.5 mA) for muscle stimulation. Two legs of the same rat are divided into two testing groups: Group A stimulates two electrode pairs alternatively, while Group B stimulates the fixed electrode pair. After the muscle training, the testing results of both groups are shown in

Table 1. For Group A (alternating electrode pairs), leg displacement drops are 45% lower than Group B (fixed electrode pair). It shows that multi-channel electrical stimulation helps to reduce the muscle fatigue.

Figure 1. Schematic illustration of muscle electrode

Figure 2.

Stimulate the rat by attaching electrode to the exposed biceps femoris muscle

Table 1. Results of muscle fatigue

Figure 3. Leg movement with different electrode combinations


Selective Recording and Stimulation on Peripheral Nerves using

Flexible Sling Electrodes

Sanghoon Lee 1,2 , Shih-Cheng Yen 1,2 , Xiang Zhuolin



and Chengkuo Lee



, Ning Xue 3 , Nitish V.


Department of Electrical & Computer Engineering,

National University of Singapore, 4 Engineering Drive 3, Singapore 117576

2 Singapore Institute for Neurotechnology (SiNAPSE),

National University of Singapore, 28 Medical Drive, #05-COR, Singapore 117456


Institute of Microelectronics, A*STAR, Singapore 117685


Department of Biomedical Engineering, School of Medicine,

Johns Hopkins University, Baltimore, MD 21205, USA



Electroceuticals that modulate neural impulses for controlling the body, repairing lost function and restoring health have been recently emerging as a potentially powerful way to treat many diseases and conditions [1].

Currently, the most challenging thing is developing implantable electrical devices which should closely attach to the nerves for decades without causing damage. In addition, other desirable characteristics include, reliability and bi-directional maintenance of high-resolution recording and stimulation interfaces [1,2].

This paper demonstrates bi-directional selective recording and stimulation by using flexible and adjustable sling electrodes for electroceuticals.

The sling design enables reliable implantations on the nerves with less pressure and tight contact due to tiltedsling bridges (Figure 1). Elicited compound neural action potentials (CNAP) are successfully recorded from six sensing electrodes with different amplitudes and latencies, showing relatively selective recordings (Figure 2). In addition, selective stimulations are also conducted with recording compound muscle action potentials from gastrocnemius and tibialis anterior muscles, showing different selectivity, depending on spatial positions of stimulating electrodes. Overall, our data shows that this sling design would be effective in bi-directional electroceutical applications in the near future.

Figure 1. Schematic diagram of experimental setup and

(a) implanting flexible sling electrode. (b) A picture of

Figure 2. (a) Schematic diagram of implanted electrodes positioned on sciatic nerve and pseudo-tripolar configuration implanted flexible sling electrode on a rat sciatic nerve.

(c) Schematic diagram of implanted loop-hook electrode for recording (inset). (b) CNAP recordings from six channels at the stimulation parameter; 20 μs, monophasic, 0.8 mA. on muscles.

[1] Famm, K.; Litt, B.; Tracey, K. J.; Boyden, E. S.; and Slaoui, M. “A jump-start for electroceuticals”,

Nature 2013, 496, 159


Reardon, S. “Electroceuticals spark interest”,

Nature 2014 , 511, 18


Inkjet-printed Ag Microelectrodes for Flexible Proximity

Capacitance Sensor

Van-Thai Tran


, Thanh-Giang La


, Hongyi Yang


, Yuefan Wei



Gih-Keong Lau


and Hejun Du



School of Mechanical & Aerospace Engineering, Nanyang Technological University,

Singapore 639798


Singapore Institute of Manufacturing Technology, Singapore 638075

Flexible electronics have highlighted the challenge of compliant electrodes, which are needed to maintain electrical conductivity when highly stretched on soft substrates.

These compliant electrodes can be patterned metals, carbons or conductive liquids.

However, carbon-based and liquid electrodes are prone to degradation, vaporization, and leakage, leading to short lifetimes. Conversely, foldable metallic thin films or nanowires show superior conductivity and stable functions. However, there are challenges in the fabrication and patterning of these materials. Hence, the integration of metallic electrodes to soft structures is limited to a few choices of bendable substrates, such as polyethylene terephthalate (PET) and high-modulus polydimethylsiloxane (PDMS).

In this work, it is demonstrated that silver nanoparticles can be directly printed onto a highly stretched acrylic elastomer (3M VHB) to make a stretchable and implantable sensor. In our work, micro-wired electrodes were fabricated by inkjet printing silver nanoparticles ink under room temperature condition, followed by annealing at low temperature (up to 60 o

C). Such Ag micro-wires were demonstrated as compliant microelectrodes for sensing interception of a fringe field as a proximity sensor. This preliminary attempt shows great potential for flexible, wearable sub-micron sensors and actuators.

(a) Schematic of capacitance sensing by interrupting fringe field of the proximity sensor. (b) A 3D diagram of the sensor. (c) Front-view photograph of printed Ag microwires on a glass substrate as a sensor. (d) Capacitance sensing of two events (far and near objects sensing). (e) A flexible sensor on human finger.


A Multifunctional Electronic Skin

Xintong Guo, Lihua Wu, Hua Wang, Xiaodong Chen*

School of Materials Science and Engineering,

Nanyang Technological University, N4.1, 50 Nanyang Avenue, Singapore 639798

Human skin has self-healing sensor networks, which assist us in interacting with the surrounding environment. In order to mimic the sensing function of natural skin, a wide range of skin-like pressure and strain sensors have been developed for the application of electronic skin. However, in comparison with natural skin, current electronic skin devices have limited properties and functionalities. Thus, it is a challenge to integrate a multifunctional electronic skin device with capabilities of selfhealing, self-cleaning and pressure and flexion sensitivities. In this project, we achieved a self-healing composite with different properties, such as pressure and flexion sensitivities, which were dependent on the amount of inorganic fillers being dispersed within the supramolecular organic polymer. Investigations were conducted to illustrate how the composite responses with different applied mechanical forces. An excellent self-healing composite was fabricated and it is related to the amount of fillers incorporated within the supramolecular organic polymer. Moreover, the self-healing composite has the ability to self-clean, which has never been integrated in composites before. The ability of the composite to self-clean depends on the photocatalysis of the fillers. When fillers receive light energy equal or greater than its band gap energy, it can destroy organic pollutants effectively. The experimental results exhibit that piezoresistive and conductive materials can mimic the repeatable self-healing capability of human skin, thereby, dramatically increasing the range of application of electronic skin.


The Internet of Everything Wearable Breast Cancer Screening

System (iTBra): Empowering Early Detection

E Y K Ng 1 , S Vinitha Sree 2 and Rob Royea 2


School of Mechanical and Aerospace Engineering,

Nanyang Technological University, Singapore 639798


First Warning Systems, Cyrcadia Health, Inc., Reno, Nevada 89502, USA

Keywords :

Circadian Biometric Recorder (CBR); Thermal metabolomics; Circadian rhythm;

Breast cancer; Predictive analytics; Classification; Early detection, Non-invasive wearable online technology, Dense breast tissue screening alternative, Global Big Data

Breast Cancer Library, Improved surgical decision indication.


Early breast cancer detection can save many lives, but it is still not the gold standard mammogram we desire. Our non-invasive First Warning System (FWS) wearable online technology can detect earliest cancer signs with all dense tissue types for all age ranges, as proven by FDA trials. Physicians now have better decision making data to improve costs, outcomes and life quality.


The thermal-metabolomics profile or thermal fingerprint represents the timely collection of all metabolic activity in a biological cell, tissue, organ, or organisms, which is the end product of cellular processes. Such changes in the surface temperature or thermal fingerprints are captured by our 1 st

generation CBR



1) over a period of 48 hours using 16 contact thermistors placed over the breasts [1-3].

The key difference between our CBR TM and other breast cancer detection modalities is that CBR


is a dynamic test that collects discrete temperature values over a period of time.

Figure 1: First Warning System Circadian Biometric Recorder (1 st Prototype CBR TM )

The FWS’s proprietary ‘Advanced Predictive Analytics with Clinical Decision Support

Systems’ [4] capture a physiological profile of the changing breast over time, so as to identify breast tissue abnormalities at their earliest stages as biomarkers. It analyses patient breast health data to deliver an interpretation report to the primary care physician with an industry-leading 90% accuracy.

When / Where? The team worked on the product since June 2007. Figure 2 shows the on-going FDA final phase clinical trial for wireless 2 nd

generation high resolution sensors CBR


. Three USA patents comprising Process, System and Methods have been granted [5]. The 510(k) number K881813 was issued by the Food and Drug

Administration (FDA), USA which is the clearance number given as premarket notification. The Euro CE Mark for marketing (Figure 3) in the UK, EU and Russia markets is expected in 2016. The FWS & patents are being commercialized by Cyrcadia

Health, Inc, USA.


Figure 2: On-going FDA Trial for 2 nd generation wireless CBR TM

In sum: We use data mining (WRUBAC) techniques on the multidimensional time series dataset to predict benign and malignant cases. A generalized classification framework is developed and comprises: (a) a data pre-processing element, (b) a feature selection element, (c) a classifier development element, and (d) a classifier evaluation element. FWS detects circadian cellular changes through thermal dynamic selection processes, allowing earlier, safer, and more accurate cancer prediction for women of all ages and tissue types, so as to reduce the number of necessary radiation procedures, while eliminating unnecessary surgeries.

Figure 3: Marketing Strategy upon FDA’s Approval


Tan, JMY, Ng, E. Y.K., R Acharya U, Keith, L.G., and Holmes, J., “Comparative

Study on the use of Analytical Software to Identify the Different Stages of Breast

Cancer using Discrete Temperature Data”, Journal of Medical Systems , 2009, 3(2),

141-153. (DOI: 10.1007/s10916-008-9174-4)


Ng, E. Y.K., R Acharya U, Keith, L.G., and Lockwood, S., “Detection and

Classification of Breast Cancer using Neural Classifiers with First Warning

Thermal Sensors”,

Information Sciences, 2007, 177(20), 4526-4538. Selected abstract for "Communications in Computer and Information Science" (2009).

[3] Ng E.Y.K., Tan MS, Lockwood S, Keith LG, ANN based Classification of Breast

Cancer with Discrete Temperature Screening: Facts and Myths, pp. 403-439. Chp.

21, Book Chapters in Emerging Technologies in Breast Imaging and

Mammography, J.S. Suri, R.M. Rangayyan and S Laxminarayan (Eds.), American

Scientific Publishers, USA, ISBN: 1-58883-090-X2008, 2006.

[4] S Vinitha Sree, Ng, E.Y.K., R Acharya U, and Jim Holmes “Evaluation of First

Warning Systems Circadian Biometric Recorder


, a wearable breast cancer detection device - A Predictive Analytics Paradigm”, Applied Soft Computing, (inpress)


[5] Three Granted US Patents No: 8,185,485 B2: Method/Process (2008); 8,231,542

B2: Utility: System (2012) and 8,226,572 B2: Utility: Methods (2012)

Special Thanks to

Analytical Technologies Pte Ltd

Bruker Singapore Pte Ltd

Leica Microsystems

Nanoscale Horizons

Raith Nanofabrication

WITec GmbH