Karl Booksh School of Biochemistry Arizona State University (Tempe) Denise Wilson Department of Electrical Engineering University of Washington (Seattle)

Karl BookshSchool of Biochemistry

Arizona State University (Tempe)

Denise WilsonDepartment of Electrical Engineering

University of Washington (Seattle)

National Science Foundation, Grant #ECS0300537

Surface Plasmon Resonance Portable Biochemical Sensing Systems

• The Big Picture– Why SPR?

• Highly sensitive (10-4 to 10-6 RI units)• Very local (10-100nm from sensing surface)• Directly indicative (of interactions between sensor and environment)• Relatively unencumbered by sampling overhead (e.g. tagging, mixing, etc)• Readily referenced to compensate for background fluctuations (e.g. drift)

– How is it used (SPR = transduction mechanism)?• Non-functionalized = bulk refractive index• Functionalized = specific analytes

– The Full Spectrum of SPR-based instruments• User-Intensive, Single Measurements: Biacore• User-Intensive, Single Field Measurements: TI Spreeta (Chinowsky/Yee)• Distributed and Autonomous, Multiple Measurements:

– Insertion-based probes– Compact signal processing– Streamlined, robust optical path


ECS0300537

• Who are we?– Karl Booksh, Biochemistry, Arizona State University (Probes and Functionalization)– Denise Wilson, Electrical Engineering, University of Washington (Signal Processing and

Systems Integration)– Are we interdisciplinary? Tight integration of biochemistry and electrical engineering

• Goal of this Research– Surface Plasmon Resonance

• Field monitoring at numerous locations• What defines the problem?

– Ability to sense specific analytes at high sensitivity/low detection limit– With high resilience to ambient fluctuations

• light, temperature, • other factors that influence bulk refractive index

– In a manner that allows continuous sampling with little overhead– In a footprint that is non-intrusive or easily carried (handheld)



Basic Operation

When the wave vector closely matches that of the surface plasmon at the metal-sample interface, reflected light is significantly attenuated

Optical Fiber w/ CladdingGold Coating

Exposed Core

Metal

θinc

Sample

Substrate

Evanescent Wave

Surface Plasma Wave

Incident Light

Reflected Light

ko = 2/

Surface Plasmon ResonancePortable Biochemical Sensing

Systems Configurations

• Point of resonance can be detected at a – Particular angle (constant

wavelengh interrogation)– Particular wavelength (constant

angle interrogation)

• Constant Angle– Polychromatic light source at

constant angle of incidence

• Constant Wavelength– Monochromatic light source at

different angles of incidence

Constant Angle is chosen here for: inexpensive light source, easy alignment, and simpler, more compact configuration (= less overhead)


Sensor Design

The probe configuration is :

• easily replaced, easy to use

• Less prone to sensor layer blocking,

but can be

• more sensitive to ambient fluctuations

• more susceptible to fouling

Sampling Options:

• In-line

• “Dip” insertion-based probe


Typical Output

Air

Raw Data (background overwhelms resonance)Referenced Data (Resonance is evident)

Increasing RI


Summary of Effort

Multivariate Calibration

High Resolution Photodetection

Communication/ADC Overhead

Measurement to Reference Ratio

High Resolution Regression

Software

Low Resolution Photodetection

Integration Time Programming

“Flatlining” Reference Ratio

Low Resolution Regression

Software

Approach #1 (Traditional)Multivariate Calibration

Approach #2 (Voltage-Mode, Partially Integrated)


Summary of Effort



“Flatlining” Current Scaling

Conversion to Pulse Mode


Software

Approach #3 (Pulse-Mode, Fully Integrated)



Dark Current Compensation

“Flatlining” Current Scaling


Software

Approach #4 (Current-Mode, Fully Integrated)


System-on-Chip Implementations

Idark

...

...

Sp_0 Sp_1

6/6

6/6 6/9

6/9

4/44/44/4

6/6

6/6

6/12

6/12

Sp_7

Vdd

Mdark*Idark

VbiasVset

(a)

CholdVbuff

Vi

18/6

Vi’Vi”

Hold18/6

6/6 6/6

18/6

6/6

6/12

6/6

18/6

6/6

6/66/12

15/6 C

Precharge

18/6

6/6

18/6

6/6

Vcomp

18/6

6/6

6/6

18/6

6/6

Vi Vref

Approach #4

Approach #2

Approach #3

All Designs are mixed signal, fabricated in

standard CMOS



Pixel

Analog Sampling

Digital Control

Phototransistor

15 pixel array fabricated on a 1cm2 die in the 1.5 micron AMI process through MOSIS

2mm



Approach Traditional Voltage Mode Pulse Mode Current Mode

Prediction Error 6.07% 6.05% 7.8%

RI Resolution 5 X 10-4 2 X 10-4 6 X 10-4

Approach SOC Integration

Size

(X )

Traditional None Big

Voltage Mode Partial 200 X 1800

Pulse Mode Full 200 X 1200

Current Mode Full 200 X 1000

• What’s the bottom line?– Benchmarking has shown system-on-chip to be competitive with software solutions– Compact, low user-overhead, low-power SPR nodes have been enabled:

• Environmental Monitoring (e.g. coastal/ocean/freshwater)• Denise sensor networks for maintaining public safety (e.g. water supply) • Biomedical applications (e.g. point of care, preventative heart attack

monitoring)– Students (3 MS, 2 undergraduate, 2 of which are women)– Outreach/Broader Impact

• SPR modeling and simulation integrated into electronic nose toolbox• www.ee.washington.edu/research/enose

– Technology Transfer• Probe design is patented and licensed to two companies in Phoenix• SOC designs are fabricated in standard CMOS• Optical components are modular and readily available


• Publications– Denise M. Wilson and Lisa E. Hansen, “Current-mode System-on-Chip for SPR Sensing Systems,”

IEEE Sensors Journal, submitted for publication, June 2006. – Lisa E. Hansen and Denise M. Wilson, “System-on-chip Surface Plasmon Resonance Sensors Using

Pulse-based Interface Circuits,” IEEE Sensors Journal, submitted for publication, March 2006. – M.W. Johnston, Lisa E. Hansen, and Denise M. Wilson, “System-on-Chip Circuit Architecture for

Eliminating Interferents in Surface Plasmon Resonance Sensing Systems,” IEEE Sensors Journal, submitted for publication, January 2006.

– Lisa E. Hansen, Matthew Johnston, and Denise M. Wilson, “System-on-chip Surface Plasmon Resonance Sensors Using Pulse-based Interface Circuits,” IEEE Sensors: Irvine, California, October 2005.

– Matthew Johnston, Denise Wilson, Karl Booksh, and Jeffrey Cramer, “Integrated Optical Computing: System on Chip for Surface Plasmon Resonance Imaging,” Intl. Symp. Circuits and Systems, ISCAS: Kobe, Japan, May 2005.

– Lisa Hansen, Matthew Johnston, and Denise Wilson, “Pulse-based Interface Circuits for SPR Sensing Systems,” Intl. Symp. Circuits and Systems, ISCAS: Kobe, Japan, May 2005.

– Denise M. Wilson, Mike Warren, Karl Booksh, and Louis Obando, “Integrated Optical Computing for Portable, Real-time SPR Analysis of Environmental Pollutants,” Eurosensors 2002: Prague, Czech Republic, September 2002.


Documents

Karl Booksh School of Biochemistry Arizona State University (Tempe) Denise Wilson Department of Electrical Engineering University of Washington (Seattle)