Border Security and Smart Sensors

Dr. Michael EastmanDepartment 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 Security-supported 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 SecurityAreas 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

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.

Piezoelectric and Piezoresistive Materials

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

SensorElement

Substrate

Schematic of Sensor Based on Cantilever Technology

Piezoresistive Microcantilever

Biolayer

Substrate

Schematic of Biosensor Based on Cantilever

Piezoresistive Microcantilever

Technology

Viral DetectionViral 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

Many different bioactive sensor substrates, may be specific or may respond in a characteristic pattern

Scanning Ohmmeter

Dr. Tim Porter

Physics, N.A.U

Cantimer CorporationMenlo 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 OsmolalitypHRatio of key electrolytes such as sodium and potassiumPregnancy 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 detectionViruses, proteins, antibodiesProtein 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

(a) As Fabricated

(b) Response to Target Analyte

Sensing Polymer

MicroCantilever

Swollen Polymer

R

R

• Saliva is a proven hydration biomarker • Patented MEMs “Universal Sensor”• Proprietary analyte responsive polymers• Integrated electronics and microfluidics

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 0.15-0.20°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

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

~ $10 billionN/A2,590,000Secondary Diagnosis

~ $2 billion2,094,000568,000Primary Diagnosis

CostDays of CareHospitalizationsAcute Dehydration

--- 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

Phase II Product Development

0

20

40

60

80

100

120

140

160

180

0:00 0:28 0:57 1:26 1:55 2:24 2:52 3:21

Cum ulative Tim e

Osm

ola

lity

Exercise Recovery

2% Body Water Loss

No Body Water Loss

Incline Walking Challenge - 2% Water Loss

50 Mile Bike Ride – Santa Cruz Mtns.

50 mile Bike Ride: Active Hours vs Saliva Osmolality

20

30

40

50

60

70

80

90

100

110

120

0 1 2 3 4 5 6

Hours on Ride

Sal

iva

Osm

ola

lity

(mO

sm)

--- Three Products ---

Phase II Product Development

RF

All have dual roles: ● Immediate utility

&● Initial member of

product family

PDA

Digital Osmometer

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

H

F

Representations of the molecular structure of the vinylidene difluoride (VD) monomer and of the and

forms of the PVDF polymer.

F

H

H

F

PVDF- form

PVDF- form

VD-wire

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 ~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

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 ~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

Collection and Transmission of Data

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