karl booksh school of biochemistry arizona state university (tempe) denise wilson department of...
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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
Surface Plasmon Resonance Portable Biochemical Sensing Systems
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)
Surface Plasmon Resonance Portable Biochemical Sensing Systems
Surface Plasmon Resonance Portable Biochemical Sensing Systems
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)
Surface Plasmon Resonance Portable Biochemical Sensing Systems
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
Surface Plasmon Resonance Portable Biochemical Sensing Systems
Typical Output
Air
Raw Data (background overwhelms resonance)Referenced Data (Resonance is evident)
Increasing RI
Surface Plasmon Resonance Portable Biochemical Sensing Systems
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)
Surface Plasmon Resonance Portable Biochemical Sensing Systems
Summary of Effort
Multivariate Calibration
Low Resolution Photodetection
“Flatlining” Current Scaling
Conversion to Pulse Mode
Low Resolution Regression
Software
Approach #3 (Pulse-Mode, Fully Integrated)
Multivariate Calibration
Low Resolution Photodetection
Dark Current Compensation
“Flatlining” Current Scaling
Low Resolution Regression
Software
Approach #4 (Current-Mode, Fully Integrated)
Surface Plasmon Resonance Portable Biochemical Sensing Systems
System-on-Chip Implementations
Idark
...
...
Sp_0 Sp_1
6/6
6/6 6/9
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4/44/44/4
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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
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Vi Vref
Approach #4
Approach #2
Approach #3
All Designs are mixed signal, fabricated in
standard CMOS
Surface Plasmon Resonance Portable Biochemical Sensing Systems
System-on-Chip Implementations
Pixel
Analog Sampling
Digital Control
Phototransistor
15 pixel array fabricated on a 1cm2 die in the 1.5 micron AMI process through MOSIS
2mm
Surface Plasmon Resonance Portable Biochemical Sensing Systems
System-on-Chip Implementations
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
Surface Plasmon Resonance Portable Biochemical Sensing Systems
• 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.
Surface Plasmon Resonance Portable Biochemical Sensing Systems