Border Security and Smart
Sensors
Dr. Michael Eastman
Department of Chemistry
The University of Texas at El Paso
UTEP and Border Security
• The University of Texas at El Paso is the home of the
National Center for Border Security and Immigration.
• The center, a U.S Department of Homeland Securitysupported research and degree program focused on
producing border, homeland security and
immigration experts, will be a partnership with the
University of Arizona. Funding $1M/year.
• Border Security Conference: 2007,2006,2005
UTEP-Research for Today Education for Tomorrow
UTEP Indio Mountains Research
Station
Smart Sensors
• We will use the term “Smart Sensor” to refer to
systems that employs a sensor device mated to
microelectronics. In lab work a computer will
take the place of the microelectronics. Lab
systems are not engineered to minimize size and
power consumption but clearly those would be
goals in any widely deployed practical device.
• We also want our “Smart Sensors” to be rugged
and inexpensive.
Smart Sensors and Border Security
Areas of Interest
• Bioterrorism-disease organisms, biodisrupters
• Clandestine monitoring-vibration, pressure,
chemicals, temperature
• Health and health monitoring-humans as well as
plants and animals
– Effectiveness of first responders (hydration/heat
stress)
– “Slow” Bioterrorism
– “Test to treat”(fast)-who should receive scarce
vaccines/antidotes-triage
Piezoelectric and Piezoresistive Materials
With piezoelectric materials there is a separation of charge which generates a net
dipole- stressing the material generates a voltage . Examples: Inorganic: barium
titanate (BiTiO3) and lithium niobate (LiNbO3); Biological materials: bone, tendons,
sugar, dentin. Polymers: PVDF. Piezoresistive materials respond to mechanical stress
with a change in electrical resistance. Examples: Silicon, Germanium.
http://en.wikipedia.org/wiki/Piezoelectricity
Chemisensors and Biosensors Utilizing
Piezoresistive Microcantilevers
• Robust, small and
inexpensive allows sensing of
both biological agents and
chemical agents from a single
platform. 1 ohm response for
400 angstrom change in the
thickness of the sensing layer.
• Patents awarded, currently
being developed as hydration
sensor & “test to treat” sensor
by Cantimer Corporation,
Menlo Park, CA
Piezoresistive Microcantilever
Sensor
Element
Substrate
Schematic of Sensor Based on Cantilever Technolog y
Piezoresistive Microcantilever
Biolayer
Substrate
Schematic of Biosensor Based on Cantilever
Technology
Viral Detection
Glass slide with antibody
layer attached
After exposure to dilute
vaccinia virus solution
Dr. Tim Porter
Physics, N.A.U
Viral Detection in Solution
(virus sizes 100 to 3000 angstroms)
Dr. Tim Porter
Physics, N.A.U
Sensor Array
Scanning Ohmmeter
Many different bioactive sensor substrates, may be
specific or may respond in a characteristic pattern
Dr. Tim Porter
Physics, N.A.U
Cantimer Corporation
Menlo Park California
Vision: Cantimer is developing piezoresistive
sensors for a wide range of applications
including determination of hydration state and
medical diagnostics
Potential Sensor Applications
Medical:
Saliva, Blood Serum, and Urine Osmolality
pH
Ratio of key electrolytes such as sodium and potassium
Pregnancy indicator (HCG)
Drug testing (amphetamine, cocaine, marijuana, etc.)
Glucose
Chemical:
Toxic gas sensors (Homeland Security, Industrial)
Chemicals in water (TCE, MTBE, CCl4 etc.)
Air quality, point sensors, process streams
Biological:
DNA sequence detection
Viruses, proteins, antibodies
Protein binding and drug discovery
Principal Developers of the Piezoresistive
Microcantilever Systems
• Dr. Ray Stewart & Co-workers, Bay
Materials/Cantimer Corporation, Menlo Park,
CA.
• Dr. Tim Porter & Co-workers, Department of
Physics and Astronomy, Northern Arizona
University, Flagstaff, AZ
• Dr. Michael Eastman, Professor of Chemistry,
UTEP, El Paso, TX
Cantimer’s Technology Platform
• Saliva is a proven hydration biomarker
• Patented MEMs “Universal Sensor”
• Proprietary analyte responsive polymers
• Integrated electronics and microfluidics
MicroCantilever
R
Sensing Polymer
(a) As Fabricated
Swollen Polymer
R
(b) Response to Target Analyte
First Responders and Military are
concerned about dehydration
• Lack of adequate hydration impairs the body's
ability to maintain a stable core temperature,
and decreases strength, endurance, and blood
volume. Core body temperature rises 0.150.20°C for each 1% loss in body mass.
Furthermore, for each 1% loss in body mass,
heart rate increases by 3-5 beats/min.
Progressive acute dehydration can lead to a
significant increase in cardiovascular strain.
Medical Effects of Dehydration
Acute Dehydration
Primary Diagnosis
Secondary Diagnosis
Hospitalizations
Days of Care
Cost
568,000
2,094,000
~ $2 billion
2,590,000
N/A
~ $10 billion
Chronic Dehydration
Impact
Population at Risk
Pressure ulcers
Time to heal
> 1,000,000 in SNF alone
Urinary Infections
Increased incidence
8,300,000 Anually
Renal failure
Increased incidence
> 80,000 Annually in elderly
Diabetes
Insulin response
18,000,000 diabetics in U.S.
Falls
Increased risk
40% of elder injuries
Pneumonia
Increased incidence
4,800,000 in U.S. per year
Phase II Product Development
--- Digital Osmometer Features ---
 Phase II deliverable
 Point in time measurement
 More portable, less power, less cost
 Close to vision of end product
 simple electronic package
 signal analysis algorithm
 Future physiological studies
Incline Walking Challenge - 2% Water Loss
180
2% Body Water Loss
160
140
No Body Water Loss
Osmolality
120
100
80
60
Exercise
Recovery
40
20
0
0:00
0:28
0:57
1:26
1:55
Cum ulative Tim e
2:24
2:52
3:21
50 Mile Bike Ride – Santa Cruz Mtns.
50 mile Bike Ride:
Active Hours vs Saliva Osmolality
Saliva Osmolality (mOsm)
120
110
100
90
80
70
60
50
40
30
20
0
1
2
3
Hours on Ride
4
5
6
Phase II Product Development
--- Three Products --PDA
Digital Osmometer
All have dual roles:
● Immediate utility
&
● Initial member of
product family
RF
Work on PVDF Piezoelectric Sensors
• Done in conjunction with a Materials Science
educational project sponsored by the Army
• Mr. Guillermo Carbajal, Dr. C. V. Ramana,
UTEP, Department of Metallurgy/Materials
• Dr. R. C. Hughes, Sandia National Labs
PVDF- Basics
• Polyvinylidene difluoride (PVDF),is also known under various
trade names including _KYNAR (Trade Mark: Elf Atochem
North American) SOEF (Trade Mark: Solvay S. A.)
• PVDF is prepared by the polymerization of 1,1-vinylidene
difluoride
• The structure of the monomer is:
• The structure of the polymer is:
F
H
F
H
Representations of the molecular structure of the
vinylidene difluoride (VD) monomer and of the a and b
forms of the PVDF polymer.
F
H
F
H
VD-wire
PVDF-b form
PVDF-a form
VD-space filling
PVDF Sensors
• PVDF is piezoelectric and the voltage induced by
bending PVDF films can be measured. The surface of
the PVDF is coated with metal to allow electrical
measurements.
• PVDF is pyroelectric and readily absorbs thermal
radiation with a wavelength at l ~104 nm . The
voltage induced by exposing metalized PVDF films to
thermal radiation can be measured.
• By virtue of its piezoelectric properties PVDF possibly
could be fabricated into a surface acoustic wave
based sensing system.
Commercially available metal coated
piezoelectric PVDF sensor elements
A Film
in (mm)
B Electrode
in (mm)
C Film
in (mm)
D Electrode
in (mm)
t (µm)
Cap (nF)
.520 (13)
.400 (10)
.980 (25)
.580 (14.70)
205
.500
.640 (16)
.484 (12)
1.63 (41)
1.19 (30.17)
205
1.38
PVDF sensors mounted on a solid substrate and
interfaced to circuit similar to “Circuit A”
PVDF sensor elements,
Circuit (A) and USB data port
Output PVDF sensors on flexed ruler
damped motion-Note polarity
(green/yellow) and combined signal.
Pyroelectric Matrix Array
• PVDF is pyroelectric (pyroelectric materials
are also piezoelectric) and readily absorbs
radiation with a wavelength at l ~104 nm .
• Four sensors in matrix array.
• Array capable of quantifying the heat
intensity and the location of the heat source.
Four Panel Thermal Detection
Voltage output 4 panel Pyroelectric Sensor when exposed
to an asymmetrically located heat source
Suite of Sensors for Comprehensive
Reconnaissance
Thermal
Chemical
Biochemical
Vibration/Motion
Collection and Transmission of Data
Microprocessor and radio transmitter
Chemical
Biosensor Sensor
Motion
Sensor
Thermal
Sensor
Acknowledgements
• This material is based upon work supported in
part by the U. S. Army Research Laboratory
and the U.S. Army research Office under
Contract W911NF0410052.
• Dr. Ray Stewart- Cantimer Corporation
• Dr. Tim Porter- Northern Arizona University
• Mr. Guillermo Carbajal and Dr. C. V. Ramana
Thank You