MCEN 5208 Introduction to Research Fall 2008
Dielectrophoretic Nanowire Placement and Solutions to
Nanowire Bonding
Student
Alicia Baca
Advisor
Victor M. Bright
Abstract: The precise and efficient placement of nanowires is necessary for characterizing
and testing their mechanical and electrical behavior. Bonding the nanowires in their placed
location is also necessary for this type of experimentation. Each of these practices has been an
ongoing challenge in NEMS characterization, and few attempts have thus far been made at
finding solutions.
Dielectrophoresis is defined as the controlled motion of polarized particles in a non-uniform
electric field. By demonstrating consistent, accurate results, dielectrophoresis could prove to
be the most efficient and successful method of nanowire placement. Peak-to-peak voltage,
frequency, and the solvent used for suspension are all factors to be considered. The goal for
this part of the project would be to determine the ideal solution for each factor.
Indium forms a good ohmic contact with gallium nitride, making it an excellent material for
investigating the mechanical and electrical behavior of nanowires. Indium is also a good alloy
for gold (the electrode metal used for dielectrophoresis) resulting in good wettability and a
slow diffusion rate. Evaporation of indium used to bond nanowires in place has never been
done before. If proven to be reliable, evaporation would not only be an innovative method for
bonding, but also very cost effective. Patterning and thickness of metal, along with
evaporation process would be key factors to determine for successful results
Project Descriptions: Updated 2/12/2016 Page 1
MCEN 5208 Introduction to Research Fall 2008
The fabrication of window atom chips for BEC Channel
Cells
Student
Jian Wang
Advisor
Victor M. Bright
Abstract: Bose-Einstein condensates of ultracold atoms have been experimentally realizable
for several years and some of the advantages of microscopic magnetic traps on a chip have
been described before. On an atom trapping chip, modest electric currents can produce large
magnetic field gradients and curvatures in close proximity to a planar arrangement of wires.
Microfabricated parallel conductors are used in a last stage of evaporative cooling to achieve
Bose-Einstein Condensation (BEC). Lithographic fabrication techniques now make it possible
to integrate ever complex systems of many microscopic traps, waveguides and other atomoptical devices on a single “atom chip”. This project will focus on investigating the method
for fabricating through-wafer interconnects in atom trapping chips used in ultra-high-vacuum
atom-optics cells for Bose-Einstein Condensation (BEC) experiments and proposing a new
method of opening a window on the atom chips for imaging laser beam.
Expected accomplishments:
1. The distance from the edge of this window to the copper wires should be no longer than 100
microns.
2. 5 Amps current can be conducted through the vias while the vacuum can be held under
4x10-11 Torr at room temperature.
3. The yield rate of fabricated via interconnects in this process after anodic bonding (requires
heating to 425 ºC) is higher than 90%.
Project Descriptions: Updated 2/12/2016 Page 2
MCEN 5208 Introduction to Research Fall 2008
Ultrasonic Microsensors for Real-Time Monitoring of
Inorganic Crystal Deposition on Microporous Polymeric
Membranes
Student
Zhi Yuan
Advisor
Victor Bright (victor.bright@colorado.edu) and Alan Greenberg
(Alan.Greenberg@colorado.edu)
Abstract: Microporous polymeric membranes are used in numerous liquid-separation
processes. Of particular engineering, economic and social interest is that the growing demand
for clean, fresh water has led to the explosive growth of membrane-based water-treatment
processes, especially desalination, in many parts of the world. In arid lands, seawater along
coastal regions is often employed as the feed source. Although highly saline inland brackish
waters are more readily available, such sources are not commonly used because of the high
concentrations of dissolved salts. The pretreatment costs for brackish waters can be relatively
high and the amount of water that can be recovered is correspondingly low due to the
precipitation of insoluble salts onto the membrane surface (scaling). Deposition and growth of
this scaling layer can significantly affect membrane performance and/or damage the
membrane. Depending on the nature of the scalant, the scaling deposits may or may not be
removable. Although chemical treatments (anti-scalants) are now routinely used to improve
membrane lifetime, they are expensive and are of only limited utility for increasing water
recovery from desalination. Therefore, there is considerable interest in novel approaches to
limit membrane scaling.
Current membrane-based liquid-separation processes are generally monitored by external
volumetric flow-based techniques. However, such measurements do not provide direct
information on the initiation and growth of membrane scaling. The proposed project seeks to
develop a prototype ultrasonic microsensor device mounted directly on the membrane surface
that will be incorporated into a laboratory-scale separation flow cell. This in-situ sensor will
be based on the propagation of surface acoustic waves at the feed solution-membrane interface,
and will provide capability for real-time measurement of membrane-surface scaling. Sensors
based upon the measurement of other relevant physical properties may also be considered.
The project will involve investigation of the properties of acoustic waves in liquid, solid and
porous materials as well as the effects of interfaces and interface perturbations on acoustic
signal behavior. Microfabrication techniques will be studied and employed as necessary to
develop a functioning sensor/transducer system. The overall goal of this project is to design,
fabricate, and characterize the ultrasonic surface-mounted microsensor under laboratorycontrolled membrane-scaling experiments. The project is highly interdisciplinary involving
aspects of mechanics, design and fabrication, and materials, and has a high probability of
providing future thesis support for the successful student.
.
Project Descriptions: Updated 2/12/2016 Page 3
MCEN 5208 Introduction to Research Fall 2008
Graphene Thin Films as Novel Nanoporous Membranes for
Filtrations (Project 1 of 3)
Student
Fanghao Yang
Advisor
Scott Bunch
Abstract: Graphene is a single atomic sheet of graphite and graphite is the material you find
in pencil lead. It is an amazing material with remarkable mechanical properties. It is the
stiffest, strongest, and thinnest material in the world. An intriguing application for suspended
graphene is as an ultrathin membrane barrier for gases and liquids. Ideal membranes which act
as selective barriers should be as thin as possible to increase flux and reduced blockage,
mechanically robust to prevent breakage, and have well defined pores to increase selectivity. A
graphene membrane represents the thinnest membrane possible (one layer of atoms) with the
smallest pore sizes attainable (single atomic vacancies), and unprecedented mechanical
stability. A current limitation to using graphene membranes is the difficulty of manufacturing
large area membranes. This project will focus on fabricating a uniform film of graphene sheets
over a silicon wafer by spin coating them onto a wafer. The first goal is to fabricate a graphene
film that is impermeable to gases and liquids. Once this is accomplished, the graphene will be
made permeable through various heat treatments. The final goal is to have ~ 1 nm thick
membrane with controlled pores that can be used for membrane separation technology.
.
Project Descriptions: Updated 2/12/2016 Page 4
MCEN 5208 Introduction to Research Fall 2008
Ionic Transport Across Single Atomic Layer Graphene
Sheets with Atomic Scale Pores (Project 2 of 3)
Student
Xinghui Liu
Advisor
Scott Bunch
Abstract: A second project on graphene membranes available in my group is to study ionic
transport across graphene. Single, suspended, isolated graphene sheets will be fabricated and
then heat treatment used to poke holes in them. An ionic solution will be placed on both sides
of the graphene membrane and a voltage will drive ions through these atomic pores. Since
graphene is an electrically conducting material, a voltage will be applied to the graphene which
electrostatically opens and closes these pores. This will create a single atomic layer ionic
switch. For the first time, artificial membranes separating ionic solutions will reach the size of
biological cell membranes. Eventually these graphene ionic membranes will be integrated with
ion channels to form hybrid bio/nano membranes which will be used to probe biological
interactions, make biosensors, or create artificial cells.
.
Project Descriptions: Updated 2/12/2016 Page 5
MCEN 5208 Introduction to Research Fall 2008
Graphene Drums Coupled to a Femtoliter Volume of
Trapped Gas (Project 3 of 3)
Student
Steven Koenig
Advisor
Scott Bunch
Abstract: This project will create graphene drums which couple to a small volume of trapped
gas. Drums are created by suspending graphene sheets over predefined wells in silicon oxide.
The graphene is clamped on all sides by the van der Waals force between the graphene and
SiO2, creating a ~ (μm)3 volume of confined gas. There are 2 spring constants that dominate
the vibrations in these drums. The first is the spring constant of the graphene and the second is
the spring constant of the confined gas. As the graphene moves out of plane, it compresses the
underlying gas. In graphene drums, these 2 spring constants can be made nearly equivalent.
We will measure the spring constant of this small volume of gas and use it to determine the
density and sound velocity of the trapped gas. We will investigate interactions with this
trapped gas such as acoustic air modes which may couple to the graphene drum motion. This
allows us to probe with exquisite sensitivity the properties of tiny confined volumes of gas.
.
Project Descriptions: Updated 2/12/2016 Page 6
MCEN 5208 Introduction to Research Fall 2008
CFD Modeling of a Hyperthermal Nozzle Assembly
Student
Qi Guan
Advisor
John W. Daily
Abstract: We carry out experiments to understand the thermal decomposition chemistry of
biomass during gasification. The experiments involve expanding reactant through a small
heated tube into a vacuum where the products of reaction are analyzed using laser
ionization/mass spectrometry. The object of this project is to quantitatively model the flow
field within the tube using computational fluid dynamics (CFD) so that we may directly
compare the experimental results with modeling calculations. A preliminary CFD model had
been previously developed. The project would involve perfecting the model and assisting in
the biomass gasification research by running model simulations..
Project Descriptions: Updated 2/12/2016 Page 7
MCEN 5208 Introduction to Research Fall 2008
Understanding the physical mechanisms of turbulent
liquid atomization (Project 5 of 5)
Student Xi Xia
Advisor Olivier Desjardins
Abstract: Most energy conversion devices today burn fuel that is stored in liquid
form. However, combustion takes place in the gas phase, meaning that the liquid has
to be evaporated before it can burn. Therefore, to maximize efficiency, the fuel is first
atomized into a fine spray.
Because of the complexity of the physics behind liquid atomization, the current
paradigm is to rely on phenomenological models that require fine-tuning with the aid
of experimental data. As a consequence, these over-simplified models are not
predictive, and this limitation currently represents one of the main hurdles in
advanced computational modeling of combustion engines. Therefore, there is a need
for new atomization models based on first principles that capture the complex
physical processes associated with turbulent liquid break-up and accurately predict
spray droplet size and velocity distributions.
Toward this goal, this project aims at exploiting an existing database of numerical
simulations of turbu- lent atomization in order to understand in more details the
physics of atomization. By analyzing large-scale simulation results, current
atomization models will be assessed, and detailed mechanisms will be proposed.
Expected accomplishments:
Figure 4: Simulation of a single
component spray flame
Figure 5: Simulation of turbulent
liquid atomization
1. Extensive literature review for phenomenological atomization models.
2. Assessment of these models against available computational database.
3. Detailed analysis of the physical mechanisms behind atomization.
Project Descriptions: Updated 2/12/2016 Page 8
MCEN 5208 Introduction to Research Fall 2008
Nanoscale Processing of Multiphase Polymers
(Project 1 of 4)
Student
Zhen Wang
Advisor
Yifu Ding
Abstract: Each polymer has unique chemical and physical properties. To engineer products
with comprehensive properties, polymers are often blended with small organic molecules, fillers,
and even other polymers. Macroscopic scale processing (such as extruding, embossing and
filming) of these Polymer Based Multiphase Materials (PBMM) has been practiced for decades.
Fundamental knowledge of the structure-property relationships for processing these materials
has also been relatively well established.
In contrast, processing PBMM at nanoscale has not been examined. This project aims to explore
the concepts of processing of PBMM, particularly, using Nanoimprint Lithography (NIL). Our
goal is to pursue the fundamental understanding of the phase separation behavior of polymers
under confinement, the dispersion and the surface segregation of nanoparticles in the patterned
structures, and finally the physical properties of these patterned multiphase materials.
Project Descriptions: Updated 2/12/2016 Page 9
MCEN 5208 Introduction to Research Fall 2008
Preterm Rupture of Membranes: Biomechanical and
Mechanical Influences
Student
Brandi Jackson
Advisor
Virginia Ferguson
Abstract: Placental membranes (the “amniotic sac”) that surround a fetus in utero are the only
tissue in the body that is mechanically designed to fail. In normal, term pregnancies (>37
weeks gestation), these membranes rupture spontaneously or are ruptured by a medical
professional at the onset or during parturition. However, in many cases, these membranes
undergo spontaneous rupture prematurely – the outcome of which is severe for the fetus and
may lead to infant morbidity or mortality. The phenomenon of membrane rupture is poorly
understood. Little is known about the series of biochemical events that lead to membrane
rupture, or why some membranes fail to rupture on their own. Further, the mechanical behavior
of membranes is the study of many current investigations and is just becoming understood.
The goal of this project is to link biochemical alterations that may lead to the onset of
membrane rupture to changes in the mechanical competence of placental membranes. The
student will conduct a thorough literature review on this topic, collect biochemical and
mechanical data from membrane samples provided by research colleagues at the CU Health
Sciences Center, and complete the project with a abstract and paper submission to a major
obstetrics or biomechanics conference.
Project Descriptions: Updated 2/12/2016 Page 10
MCEN 5208 Introduction to Research Fall 2008
A Novel Therapy for Bone Loss in Microgravity
Student
Rachel Paietta
Advisor
Virginia Ferguson
Abstract: Exposure to microgravity results in significantly diminished bone and muscle mass
over short durations. Bones collected from mice flown on STS-118, a Space Shuttle flight in
August of 2007, were analyzed using micro-CT and show significantly diminished volume
with microgravity exposure. However, bones from flight mice treated with a muscle
therapeutic (a myostatin inhibitor), used to treat one-half of the mice on that Shuttle flight,
appear to possess significantly greater volume (and other micro-CT metrics) as compared to
vehicle-treated controls. Since myostatin is a TGF- related protein and that TGF- is known
to be generally anabolic in bone, this muscle therapy may also prove to be anabolic to the
skeletal system. The objective of this project is to perform a comprehensive literature review
on two main topics: effects of microgravity exposure on bone and the existing body of
literature on myostatin effects on muscle and bone; collect mechanical and quantitative
histomorphometric data on these bones to better understand the changes already observed in
the micro-CT data, and to submit a conference abstract and contribute to a journal publication
to conclude the study of skeletal changes in these mice.
Project Descriptions: Updated 2/12/2016 Page 11
MCEN 5208 Introduction to Research Fall 2008
Biomechanics of the Intervertebral Disc
Student
Ross Foster
Advisor
Virginia Ferguson and Franck Vernerey (Civil Eng)
Abstract: The intervertebral disc (IVD) provides an important role in the biomechanics of the
spine. It distributes and transmits loads throughout the spine while simultaneously providing
cushioning and allowing for many degrees of freedom to the adjacent vertebrae. Research has
been done to characterize some of the various properties of the IVD, but there are still
unknowns that are yet to be determined. Preliminary research has shown that the IVD contains
fluid channels that contribute to the mechanical behavior. These fluid channels have had little
scrutiny beyond macroscopic fluid diffusion experimentation and their contribution to other
properties of the IVD is yet to be explored. Furthermore, the fiber-matrix interactions and their
contributions to the properties of the IVD needs additional investigation, and the viscoelastic
behavior of the tissue of the disc needs a more accurate characterization. Due to the inherent
biological loading of the IVD, both tensile and compression results coupled with subsequent
microscopic images will lead to a better understanding of the role of both the fluid channels
and fiber-matrix contributions to the properties of the human IVD. The outcomes of this
research will be a comprehensive literature review, collection of SEM images and mechanical
testing data, and completion of a two-page abstract to be submitted to the ASME Summer
Bioengineering Conference (in January 2009) and a draft manuscript of the final results (in
May 2009).
Project Descriptions: Updated 2/12/2016 Page 12
MCEN 5208 Introduction to Research Fall 2008
In Utero Baby Monitor
Student
Yiwei Yan
Advisor
Virginia Ferguson and Mark Rentschler
Abstract: The risk of umbilical cord accidents is grave, leading to one death (stillbirth) and
three incidences of severe disability in every 1000 pregnancies. Interestingly, pregnant women
are at greatest risk of experiencing a cord accident when they are sleeping and their blood
pressure is at its lowest. However, current technologies to monitor a fetus in utero are
extremely limited. Even in the case of high risk pregnancies, where the mother or baby has a
life threatening health condition or where the mother has previously experienced a pregnancy
loss, the most common method of monitoring a fetus is through a subjective assessment by the
mother. She is asked to pause several times a day and count fetal movements or "kicks". This
is a highly subjective measurement and is the source of a great deal of concern for many
pregnant women. Often the mother is not sensitive enough to feel the movements, the placenta
is located such that the mother cannot feel movements, or the fetus simply does not move
much (although it may also be perfectly healthy). Electronic monitoring is possible in a
hospital setting where fetal heart rate and other types of measurements are collected in real
time.
The goal of this project is to survey the literature, patent applications and other information on
the internet for the few existing fetal monitoring technologies that exist. The student will also
work with her advisors and their obstetric colleagues to determine what measurements are
needed to provide a comprehensive assessment of fetal health. The ultimate goal of this project
is to develop a patent disclosure document and also to collect proof of concept data for several
metrics (to be defined as part of this project).
Project Descriptions: Updated 2/12/2016 Page 13
MCEN 5208 Introduction to Research Fall 2008
In Vitro Flow Study of a Coarctation in a Compliant Model
of the Descending Aorta
Student
Luis Loma
Advisor
Jean Hertzberg
Abstract: Coarctation of the aorta is one of the most common congenital aortic diseases [1].
An aortic coarctation usually leads to hypertension in the upper body and pulse pressure
differential between the arms and the legs [1]. The coarctation in many cases considerably
narrows the aorta which significantly reduces blood flow. The flow of blood, by virtue of
viscosity, engenders on the luminal vessel wall and endothelial surface a frictional force per
unit area known as hemodynamic shear stress [2], and may also change the hydrostatic
pressure and cyclic strains on the endothelial cells (EC’s). Studies have shown that
hemodynamic shear stress is an important determinant of endothelial function and phenotype
[2]. It is very important to understand the regulation of endothelial cell function and gene
expression caused by shear stress. In vivo studies have been performed on rats and dogs in
order to identify the effects that elevated and reduced shear stresses have on the chemical
output of the aortic endothelial cells. However, there’s a lack of wall shear stress
characterization for aortic coarctation flows.
The purpose of the study is to investigate the fluid dynamics caused by an aortic coarctation on
an in vitro artificial model of the aortic arch and descending aorta. We will create a
physiologically correct model of the aortic arch and descending aorta containing the coarcation
out of a compliant material. The material will need to have similar material properties as the
aortic wall. Not only does the material need to have the same material properties as the aorta
but it also has to have the same reflective index as the diethyl phthalate (DEP) diluted in
ethanol. DEP in ethanol is good choice for the working fluid; it has a low viscosity, high index
of refraction, and is safe and inexpensive [3]. The viscosity and index of refraction of the
working fluid has been shown to change by changing the concentration of ethanol in the
solution. Diethyl phthalate is primarily used in industry as a plasticizer to soften a wide range
of plastics; therefore it is of extreme importance to determine if the material used is compatible
with the working fluid. However, studies have been done on the compatibility of DEP with
commonly used materials for in vitro studies. Silicone elastomer has been tested for
compatibility with DEP, and has been shown to be compatible; however the mechanical
properties of the Silicone elastomer are not an exact match. Multiple methods of fabricating
the model will be explored in order to find the method that provides the best characteristics.
There are a number of methods used to create a compliant model, but the primary method used
is the multi-step dip-spin coating method, where a positive model made from water-soluble
material is dipped into the elastomeric mixture to build the model. The multi-step dip-spin
coating method seems to be the best option at the moment. The model will be placed in an
existing flow system used for a similar experiment using a Pyrex model (shown on next page).
.
Project Descriptions: Updated 2/12/2016 Page 14
MCEN 5208 Introduction to Research Fall 2008
The flow system consists of a 25.4 x 31.8 x 20.3 cm glass tank that is partitioned into a
viewing tank and a reservoir tank, both containing the same fluid solution. The flow in the
system is driven from two 60cc syringes that are attached to a programmable stepper motor.
Two one-way check valves were incorporated into the flow system to create pulsatile flow as the
syringes cycle. Images will be taken and processed in order to determine the flow characteristics
of the fluid through the model of the aorta. From these flow characteristics we will be able to
measure the shear stress on the interior wall of the aorta, and compare these results to in vivo
results from previous studies.
References
[1] Israel, Gary, Glenn Krinsky, and Vivian Lee. "The ‘‘Skinny Aorta’’." Journal of Clinical
Imaging 26 (2002): 116-121.
[2] Malek, Adel M., Seth L. Alper, and Seigo Izumo. "Hemodynamic Shear Stress and Its Role
in Atherosclerosis." The Journal of the American Medical Association 282 (1999): 2035-2042.
[3] P. Miller, K. Danielson, G. Moody, A. Slifka, E. Drexler, and J. Hertzberg. "Matching Index
of Refraction Using a Diethyl Phthalate/Ethanol Solution for in Vitro Cardiovascular Models."
Experiments in Fluids 41 (2006): 375-381
.
Project Descriptions: Updated 2/12/2016 Page 15
MCEN 5208 Introduction to Research Fall 2008
Birefringent Fluid
Student
Charles Rareshide
Advisor
Jean Hertzberg
Abstract: A novel fluid has been developed that reveals its shear state under polarized light.
This project is to develop a model of the optical physics involved, and investigate the
feasibility of developing a quantitative measurement technique using this fluid.
Project Descriptions: Updated 2/12/2016 Page 16
MCEN 5208 Introduction to Research Fall 2008
Fluid Dynamics in a Coriolis Meter
Student
Mark Czajkowski
Advisor
David Kossoy, Joint CU-Micro Motion Research Project
Abstract: Coriolis flow meters make use of the Coriolis force in a vibrating flow tube to
measure mass flow rate and density to extremely high accuracies. The most advanced meters
can currently measure flow rate to a precision of 0.05% and density to 0.0002 g/cc when liquid
is the only phase present. Mass flow of gases can also be measured accurately. Micro Motion,
the original manufacturer of Coriolis meters, began production in the late 1970’s. The market
for Coriolis meters continues to grow as technology advances and the need to tightly control
industrial processes increases.
Surprisingly little attention has been paid to the fluid dynamics occurring inside the flow
meter. Because the actual measurement occurs on the metal tube containing the fluid, the focus
has always been on the structural design of the meter rather than on the fluid dynamics. As
Coriolis measurement performance has improved over time, fluid effects have become
increasingly relevant.
The current project would involve research in the modeling of flow physics in the flow
meter. Currently used fluid mechanics models are not very accurate for both low Reynolds
numbers. The student would be responsible for implementing improved methodologies for
predicting pressure drop on high viscosity fluids. This part of the project may not involve
Computational Fluid Dynamics, but rather will challenge the student’s overall understanding
of the mechanisms of pressure loss through a complicated pipeline component. Issues such as
pipe bends, splitters, area reductions, viscous effects, inertial effects, kinematic and dynamic
similarity, and others will come into play.
Project Descriptions: Updated 2/12/2016 Page 17
MCEN 5208 Introduction to Research Fall 2008
Nano-Electrode Assemblies for Photocatalytic Hydrogen
Generation
Student
Christine (Dolliver) White
Advisor
Se-Hee Lee, 303-492-7889
Abstract: Although hydrogen is the most abundant element in the universe, H2 must be
produced from other hydrogen-containing compounds such as fossil fuels, biomass, or
water. Each method of production requires a source of energy, i.e., thermal (heat), electrolytic
(electricity), or photolytic (light) energy. The photocatalytic dissociation of water into
hydrogen and oxygen using solar energy possesses the advantage of being an environmentally
benign and renewable source for hydrogen fuel. Photocatalysis is a process where the incident
light creates an electrical potential in the material (like in solar cells); this electrical potential is
then scientifically engineered to electrolyze water into hydrogen and oxygen. The voltage
required to overcome the dissociation potential of water is 1.23 V (but, in practice, a somewhat
higher voltage is required to overcome the overpotentials related to the kinetics). In
conventional electrolysis, electrical energy is used as the source of power to split the water. In
photocatalysis, the incident light generates this voltage within the photoelectrode and produces
hydrogen.
In this project, we propose a new generation of efficient nano-sized photoelectrodes that will
enable inexpensive generation of hydrogen from the most abundant source: water. These free
standing, individual Nano-Electrode Assemblies (NEAs) will be designed and dispersed in
water to achieve maximum surface area / catalytic activity. We will explore two different
NEA structures: WO3 nano-photoandoes, decorated with a noble metal such as Pt or Pd and a
NEA with the structural configuration of n-type WO3/W metal/p-semiconductor (NiO or
Cu2O). The research efforts proposed here will contribute a publication in peer reviewed
scientific journals. The students are expected to get involved in future collaboration with
National Renewable Energy Laboratory and gain a fundamental understanding of materials
nanotechnology in terms of material characterization and photoelectrochemical measurements.
Project Descriptions: Updated 2/12/2016 Page 18
MCEN 5208 Introduction to Research Fall 2008
Self-alignment accuracy of flip-chip soldering
Student
Ming Kong
Advisor
Y. C. Lee
Abstract: The ever increasing demand for high input/output (I/O) density, cost effective,
reliable packaging has witnessed blooming applications of flip-chip soldering in both
traditional semiconductor, photonic and MEMS industry. The solder-bumped flip-chip
technology has many advantages over the traditional packaging including high density, high
I/Os, high electrical performance, low packaging profile, and self-alignment.
Many different solder bumping processes have been developed. Among them electroplating
process is one of the most well established bumping methods. The process includes metal
deposition; thick photoresist patterning; copper stud and eutectic solder electroplating and
reflow. Recently, stencil printing has become more popular because it eliminates expensive
vacuum sputtering and photolithography process and thus offers a more cost effective bumping
method. The process involves pad pretreatment/activation, electroless Ni plating, solder paste
stencil printing and reflow. However, both processes may not achieve accurate solder selfalignment influenced by solder bump's height distribution, under bump metal (UBM)'s
fabrication accuracy and surface roughness, intermetallic compound (IMC)'s structure, and so
on. This project is to experimentally study solder self-alignment accuracies associated with
these two processes. Test vehicles will be designed, fabricated and assembled, and their selfalignment accuracies will be measured with respect to number and size of solder bumps
deposited using electroplating or solder paste stenciling printing processes.
Project Descriptions: Updated 2/12/2016 Page 19
MCEN 5208 Introduction to Research Fall 2008
Design and Fabrication of a Modified Micro Cryogenic
Cooler
Student
Ryan Lewis
Advisor
Y. C. Lee
Abstract: While the concept of refrigeration has been around for over two centuries, the
science and technology industry is still finding needs for new and improved cooling devices.
For example, superconductor-based electronics require cryogenic temperatures, and current
cryogenic cooling technology is voluminous and expensive. Micro cryogenic coolers (MCCs)
would improve the economic feasibility of superconductor-based electronics. Currently at CU,
a team is developing a MCC utilizing MEMS and the Joule-Thompson effect. Six hollow
optical fibers deliver high-pressure gas into a MEMS-based expansion valve chip. After the
gas expands and cools, it returns through a larger capillary tube. The fibers lie within the
capillary, forming a heat exchanger.
However, the current design can only cool a small amount of heat, and many applications
require greater cooling power. This project would involve modifying the current design of the
MCC to include a bundle of fibers within the heat exchanger. This project would also include
fabrication steps to couple the fiber bundle into the valve chip while avoiding leaks. The
ultimate goal is the fabrication of a MCC with greater cooling power.
Project Descriptions: Updated 2/12/2016 Page 20
MCEN 5208 Introduction to Research Fall 2008
Reliability of Atomic Layer Deposition-Based Coatings in
Water
Student
Jill Cooper
Advisor
Y.C. Lee
Abstract: Atomic layer deposition (ALD) is a technique that is used to create thin films on
the order of nanometers in thickness. ALD can be used for applications that demand highly
conformal, uniform and pure coatings.
A flexible thermal ground plane (FTGP) is being developed that will utilize both ALD-based
hydrophobic and hydrophilic coatings and hermetic sealing to protect FTGP from water loss.
The goal of this project is to identify reliable ALD coatings for these applications.
Proposed ALD coatings’ reliability needs to be tested under varying conditions and their
performance must be evaluated. The student must determine the best method to evaluate the
quality of the ALD coatings over time. Various methods have been proposed to characterize
the surface of the coatings after being exposed to water such as contact angle measurement,
scanning electron microscopy and atomic force microscopy; these and novel methods need to
be evaluated and compared in order to identify which is most appropriate for the surface
characterization. A model by which to provide accelerated testing of the surfaces must be
developed to predict the quality of the surfaces after several years of exposure to water.
.
Project Descriptions: Updated 2/12/2016 Page 21
MCEN 5208 Introduction to Research Fall 2008
Study of Diurnal and Seasonal Variations of Sesquiterpene
and Monoterpene Emissions from Vegetation
Student
Ryan Daly
Advisor
Jana Milford (CU), Detlev Helmig (INSTAAR)
Abstract: Vegetation naturally emits Biogenic Volatile Organic Compounds (BVOC's), of
which the subset of Sesquiterpene (SQT) and Monoterpene (MT) hydrocarbons are of
particular interest due to their role in atmospheric chemistry and suspected contribution to
secondary aerosol (SOA) production. Due to the highly reactive nature and low volatility of
SQT's, few studies have been reported to date. However, analytical measurement methods
have been developed to measure MT and SQT emission rates from vegetation by branch
enclosure techniques. In an upcoming field campaign (to begin as soon as possible), emission
rates of MT's and SQT's of a selected set of vegetation species will be monitored at Creekside
Nursery in Boulder, CO over a one-year period. The main motivation for this research is to
develop a better understanding of the seasonal trends and patterns of emission rates through a
one-year cycle period. Additionally, the known relationship of emission rates with diurnal
patterns should be enhanced. Data collected from this field study will be used to improve the
current MT and SQT data sets used by global biogenic emissions models such as the model of
emissions of gases and aerosols in nature (MEGAN).
Project Descriptions: Updated 2/12/2016 Page 22
MCEN 5208 Introduction to Research Fall 2008
Disinfection of Air in the Breathing Zone to Reduce
Infectious Disease Transmission
Student
Kevin Ryan
Advisor
Shelly L. Miller
Abstract: Airborne transmission of Mycobacterium tuberculosis and other infectious agents
within indoor environments has been a recognized hazard for decades. Airborne diseases are
transmitted by inhalation of small airborne particles, typically 1 to 5 microns in size, which are
generated mainly by coughing or sneezing. The probability of disease transmission typically
increases with proximity to the infectious person. The goal of this project is to design, build,
and test a control device that will reduce person-to-person airborne disease transmission, by
providing clean air in the breathing zone of susceptible persons. The device disinfects air by
using UV-C, which inactivates microorganisms by damaging their DNA so that they are
unable to replicate. This project has many design challenges, including the need to use a nontoxic UV-C light source, the device must be small in size, and the airflow through the device is
at a high velocity that results in short residence times.
Project Descriptions: Updated 2/12/2016 Page 23
MCEN 5208 Introduction to Research Fall 2008
Source Apportionment of the Denver Aerosol Sources and
Health Study data.
Student
Ricardo Piedrahita
Advisor
Shelly L. Miller and Jana Milford
Abstract: Particulate matter less than 2.5 microns in diameter (PM2.5) has been linked with a
broad array of health effects ranging from worsening of asthma and chronic obstructive
pulmonary disease to increased cardiopulmonary mortality. Determination of the sources of
PM2.5 most responsible for these health effects would allow for more efficient regulation and
improved mechanistic understanding of the problem. This has provided the motivation for the
Denver Aerosol Sources and Health (DASH) study, a multi-year source apportionment and
health effects study relying on detailed inorganic and organic speciation measurements.
Inorganic ions, elemental and organic carbon and organic molecular marker speciation data
will be used for source apportionment analysis. We will use positive matrix factorization
(PMF) as the source apportionment tool for this work, and will also conduct a qualitative
comparison with principal components analysis (PCA). This analysis will provide an estimate
of the major sources of particulate matter in Denver.
Project Descriptions: Updated 2/12/2016 Page 24
MCEN 5208 Introduction to Research Fall 2008
Micro Aerial Vehicle Systems
Student
J. McCaslin
Advisor
K. Mohseni
Abstract:I will join a team of students in Dr. Mohseni's group in design, fabrication, and testing
of Micro Aerial Vehicles (MAVs). Based on a DARPA definition a MAV is an aerial vehicle
with maximum dimension of 6 inches. A few generations of MAVs have been developed in
Professor Mohseni's group over the last few years. The most recent vehicle has a total weight of
70 grams including sensor package. The vehicles are often equipped with GPS, IMU,
atmospheric sensors, radio, and transmitter. Aerodynamic regimes of MAVs are dominated with
low Reynolds number effects and low aspect ratio. This is an unexplored flow regime. In this
study I will learn about the design, fabrication, and testing of MAVs. In particular I will
investigate aerodynamic performance of several MAV airfoils and wings. This could be
explored by wind tunnel testing in a new facility in Professor Mohseni's group or using XWing,
a new 3D MAV design tool recently developed in the group.
Project Descriptions: Updated 2/12/2016 Page 25
MCEN 5208 Introduction to Research Fall 2008
Surface Stress Induced Shifts in the Plasmon Resonant
Frequency of Metal Nanowires. Student is Xiaohu Qian.
Student
Xiaohu Qian
Advisor
Harold S. Park
Abstract: Metal nanomaterials exhibit a very unique and useful property, called surface
plasmon resonance, when illuminated with incident light. The surface plasmon resonance is a
collective excitation of the conduction electrons, which makes the nanomaterial exhibit a
certain color that is often within the visible spectrum. Of technological interest are
methodologies that enable a predictive tuning of the visible color, and in determining how the
surface plasmon resonance behaves when the nanomaterials become smaller than about 10-20
nm in size. The objective of this research project will be to utilize electrodynamic simulations
to determine how one such approach, that of applying mechanical strain, can be utilized to tune
the optical properties of metal nanowires.
Project Descriptions: Updated 2/12/2016 Page 26
MCEN 5208 Introduction to Research Fall 2008
Development of Multiscale, Atomistic-Based Constitutive
Model for Piezoelectric Nanowires
Student
Shuangxing Dai
Advisor
Harold S. Park (Collaboration with Marty Dunn)
Abstract: Piezoelectric materials are those in which mechanical strain leads to the production
of electricity. In nanomaterials, this is advantageous for energy harvesting applications, and
for self-powered NEMS that do not require a power source in order to operate. The objective
of this research project will be to develop, from atomistic principles, a multiscale constitutive
model that can predict the polarization, and therefore the electric field that arises due to
imposed mechanical deformation, with the long-range goal of being able to design highefficiency, energy harvesting nanowires.
Project Descriptions: Updated 2/12/2016 Page 27
MCEN 5208 Introduction to Research Fall 2008
In vivo Mobile Robotics
Student
Austin Ruppert
Advisor
Mark Rentschler
Abstract: This project focuses on the design and development of small mobile robotic systems
to use inside the body during surgical procedures. Initial focus will include finite element
modeling of the wheel-tissue interaction to help optimize wheel design on different tissues and
terrains. These simulations will provide data for design consideration that is specific to body
location and surgical use. Mechanical and electronics design will be included in this project as
well as laboratory testing of simple system concepts. Ultimately animal testing will help
validate performance. The expectation is that sufficient design challenges are addressed and
experimental results are obtained so that a paper can be submitted for publication review by the
end of the spring semester.
Project Descriptions: Updated 2/12/2016 Page 28
MCEN 5208 Introduction to Research Fall 2008
Nanoengineered Surface for Biosensing Phosphorylated
Proteins
Student
Ben Hamilton
Advisor
Conrad Stoldt
Abstract: Events of enzyme activation/deactivation generally involve the addition or removal
of a phosphate group. Current methods of phosphorylated protein detection require the use of
specific antibodies, limiting the range of proteins that can be detected. A novel
nanoengineered surface for biosensing phosphorylated proteins utilizing the covalent-like
stability of arginine-phosphate electrostatic interactions was created by assembling a polyArginine layer on glass. This approach is in the process of being demonstrated using purified
ovalbumin (OVA), a phosphorylated protein, and purified soybean trypsin inhibitor (STI), a
nonphosphorylated protein, both tagged with a fluorescent dye. Future work involves
establishing a calibration curve for the nonspecific binding of STI, in order to distinguish
specific binding signal from background noise. Further research with this surface, if current
testing proves successful, may include detection of other phosphoproteins in unpurified
samples.
Project Descriptions: Updated 2/12/2016 Page 29
MCEN 5208 Introduction to Research Fall 2008
Trocar Port Camera for Minimally Invasive Surgery
Student
Ben Terry
Advisor
Mark Rentschler
Abstract: The focus of this project is on the development and testing of a prototype camera-enabled
trocar port for minimally invasive surgery (MIS). MIS still suffers from poor visual feedback for the
surgical team and a constrained camera port. This project focuses on developing an integrated camera
system into a standard trocar port. Future versions could include additional sensors such as pH,
humidity, etc. Initial goals for this project include a survey of the published literature and composing a
written description of the state of the art. The bulk of the project will then focus on design and
development of a prototype camera trocar for animal testing. The design process will include regular
meetings with a surgical team, component selection, laboratory prototype assembly and testing and
ultimately testing the prototype in an animal during a surgical training course. Project goals included
development of proof of concept data and a prototype device. The expectation is that sufficient design
challenges are addressed and experimental results are obtained so that a paper can be submitted for
publication review by the end of the spring semester.
Project Descriptions: Updated 2/12/2016 Page 30
MCEN 5208 Introduction to Research Fall 2008
Quantitative Pain Measurement Device
Student
Xin Wang
Advisor
Mark Rentschler
Abstract: The focus of this project is on the development and testing of a prototype pressure pain
stimulation device. It is currently very difficult for a physician to quantitatively determine the level of
pain a patient is in. It is equally difficult for the physician to accurately determine treatment options and
perioperative and postoperative pain. The overlying goal of this project is to quantify pain on a patient
specific basis so that the physician can better treat the patient. Initial goals will include a survey of the
published literature and composing a written description of the state of the art. The bulk of the project
will then focus on design and development of a prototype pressure pain stimulation device. The design
process will include regular meetings with a medical team, design and component selection, laboratory
prototype assembly and testing and ultimately testing the prototype in a clinical setting. Project goals
included development of proof of concept data and a prototype device. The expectation is that sufficient
design challenges are addressed and experimental results are obtained so that a paper can be submitted
for publication review by the end of the spring semester.
Project Descriptions: Updated 2/12/2016 Page 31
MCEN 5208 Introduction to Research Fall 2008
Thermal and Charge Transport across Metal-Semiconductor
Interfaces (Project 3 of 6)
Student
Suraj J. Thiagarajan
Advisor
Ronggui Yang (Ronggui.Yang@Colorado.Edu)
Abstract: Thermal and charge transport across metal-semiconductor interfaces is very
important to a number of applications including energy conversion devices, electronic devices
and thermal interface materials. Studying the fundamental transport mechanisms across
materials interface has profound effect on better design of novel materials and devices. In this
project, the student will be guided to study the literature on where the community is now on
this research direction and to develop electron Boltzman transport equation based simulation
tools to study the charge and thermal transport across materials interface, in particular metalsemiconductor, metal-metal, and semiconductor-semiconductor interfaces.
Project Descriptions: Updated 2/12/2016 Page 32
MCEN 5208 Introduction to Research Fall 2008
Thermal Conductivity of Polymer Thin Films (Project 4 of 6)
Student
Jun Liu
Advisor
Ronggui Yang (Ronggui.Yang@Colorado.Edu)
Abstract: Polymers are widely used in microelectronics as packaging materials and are
finding significant and new applications in macroelectronics such as large-area organic display
panels, light emitting diodes, solar panels and batteries. Although most polymers have a low
thermal conductivity (~0.28 W/mK) that limits their heat spreading capability, the thermal
conductivity along the polymer chain can be very high (70 W/mK or higher). With a good
understanding of the mechanisms of thermal transport in polymers, we have identified curtain
approaches to significantly enhanced thermal conductivity of polymers. Polymers with
enhanced thermal conductivity will have a major impact on the packaging of both
microelectronics and macroelectroonics. The goal of this project is to (a) gain an overview of
modeling and simulation methods for thermal conductivity of polymers, especially anisotropic
thermal conductivity models, (b) perform high fidelity simulations/modeling such as molecular
dynamics simulation to study the thermal conductivity of a single polymer chain and polymer
thin films with aligned chains, and (c) measure the thermal conductivity of polymer thin films
with aligned chains by our collaborators using existing experimental facilities in the Yang lab.
Project Descriptions: Updated 2/12/2016 Page 33
MCEN 5208 Introduction to Research Fall 2008
Micro/Nano Reactive Flow and Energy Transport
(Project 5 of 6)
Student
Dave Makhija
Ronggui Yang (Ronggui.Yang@Colorado.Edu) and Kurt Maute (Aerospace
Engineering Sciences)
Abstract: Multicomponent reactive flow and energy transport is crucial to a variety of
scientific, industrial, and engineering processes, from century old stimulation of petroleum
reservoirs and environmental contaminant transport to today’s micro/nano-enabled advanced
energy conversion and storage systems, such as fuel cells and electrochemical batteries, to
name a few in energy field. This problem is challenging because it usually involves multiple
length scales and multiple processes (advection, diffusion, and chemical reaction). Over the
last few years, there are increasing interests in understanding micro/nano reactive flow and
energy transport including the development of the reactive flow lattice Boltzmann method
as current continuum reactive transport models are not valid for the micro/nano-enabled energy
and biological sensing systems.
Advisor
The goal of this project is to (a) gain an overview of modeling and simulation methods for
reactive micro/nano-flow and energy transport processes, (b) identify the weaknesses of
existing methods and the needs for high-fidelity methods, and (c) to identify a system such as
fuel cells or batteries that needs high fidelity methods, and (d) to develop a computational
model for a realistic configuration of the identified system.
Project Descriptions: Updated 2/12/2016 Page 34
MCEN 5208 Introduction to Research Fall 2008
Modeling and Experiments in Nucleate Boiling in the
Context of Power Electronics Cooling (Project 6 of 6)
Student
Lennon Rogers
Advisor
Ronggui Yang and Sreekant Narumanchi (National Renewable Energy Lab NREL))
Abstract: Nucleate boiling heat transfer is being actively pursued as a potential means of
dissipating high heat fluxes (order of 200-300 W/cm2 of higher) from electronic components.
The impact of coolant type (including novel coolants), novel surface enhancements, and
cooling mechanism (e.g. jet, spray and pool configuration) on the nucleate boiling phenomena
will be studied through both experiments and modeling. The results of the work will form the
basis of a Ph.D. dissertation and, as appropriate, will be published in scientific journals and
presented at scientific conferences. The work will be conducted at both CU and in the Power
Electronics Group at NREL.
Project Descriptions: Updated 2/12/2016 Page 35