Surface Plasmon Resonance - Research - UWEE€¦ · Reduction in peripheral components without loss...
Transcript of Surface Plasmon Resonance - Research - UWEE€¦ · Reduction in peripheral components without loss...
In commercial and research arenas, SPR is a popular transduction mechanismfor both benchtop and portable sensing systems that is both highly sensitive andreadily functionalized to sense a wide variety of chemical and biological agents.
Surface Plasmon Resonance Portable Biochemical Sensing Systems
National Science Foundation # ECS0300537
Biacore (the very big) To the very small?
A collaboration between Prof. Karl Booksh at Arizona State University andProf. Denise Wilson at the University of Washington seeks to develop anaccurate, but Very Small SPR-based sensing system.
Surface Plasmon Resonance Portable Biochemical Sensing Systems
National Science Foundation # ECS0300537
Reduction in the “footprint” of anysingle component of the SPR system,in and of itself, compromisesperformance for portability.
Surface Plasmon Resonance Portable Biochemical Sensing Systems
National Science Foundation # ECS0300537
Component Size
Light Source
Input Optics
Sensor
Output Optics
Photodetection
Signal Processing
LowFullPortable
ModeratePartialPortable
HighNoneTraditional
AccuracyLevel ofIntegration
Approach
Component Size
Light Source
Input Optics
Sensor
Output Optics
Photodetection
Signal Processing
Surface Plasmon Resonance Portable Biochemical Sensing Systems
National Science Foundation # ECS0300537
HighFullPortable
HighPartialPortable
HighNoneTraditional
AccuracyLevel ofIntegration
Approach
Comparable performance can betargeted by considering the redesignof all components at once, as asystem whose quality exceeds thesum of performance of individualcomponents.
Reduction in peripheral components without loss of performance in SPR-basedsystems can be done by:
Surface Plasmon Resonance Portable Biochemical Sensing Systems
National Science Foundation # ECS0300537
(c) Compressing thesignal processing toa single integratedcircuit (chip).
(a) Choosing a systemconfigurationamenable tominiaturization.
(b) Converting theoptical path fromdiscrete componentsto integrated fiberoptic components;
Surface Plasmon Resonance System Configuration: How it Works
When the wave vectorclosely matches that ofthe surface plasmon atthe metal-sampleinterface, reflected lightis significantlyattenuated
Optical Fiber w/ Cladding Gold Coating
Exposed Core
Metal
_inc
Sample
Substrate
EvanescentWave
Surface Plasma Wave
IncidentLight
ReflectedLight
ko = 2π/λ
Surface Plasmon Resonance System Configuration: Portable Probe Design
By placing a mirror at the end of theprobe, output light is reflected back inthe same direction as the input. Thus,the probe can be inserted into asensing overhead (no samplingrequired) rather than requiring thesensing solution to be “passed by” theSPR sensor (considerable samplingoverhead).
Surface Plasmon Resonance System Configuration: Portable Optics Path
The point at which SPRoccurs can be detected at a:
– Particular angle (constantwavelength interrogation)
– Particular wavelength (constantangle interrogation)
Constant Angle is chosen herebecause it enables aninexpensive light source(LED), easy and stable opticalalignment, and simpler, morecompact configuration.
Surface Plasmon Resonance Signal Processing:
(Cumbersome) Traditional Approach
High ResolutionPhotodetection
Communication/ADC Overhead
Measurement toReference Ratio
High ResolutionRegression
Software
Approach #1 (Traditional)MultivariateCalibration
In the traditional approach, many, many photodetector signals arescanned off of the sensing plane and then transferred to a PC forsignal processing
Surface Plasmon Resonance Signal Processing:
(Partial) Integrated Approach
MultivariateCalibration
Low ResolutionPhotodetection
Integration TimeProgramming
“Flatlining”Reference Ratio
Low ResolutionRegression
Software
Approach #2 (Voltage-Mode, Partially Integrated)
In the partially integrated approach, a much smaller number ofcustom photodetector signals are integrated in a “smart” way andthen transferred to a PC for signal processing
Surface Plasmon Resonance Signal Processing:
(Cumbersome) Traditional Approach
High ResolutionPhotodetection
Communication/ADC Overhead
Measurement toReference Ratio
High ResolutionRegression
Software
Approach #1 (Traditional)MultivariateCalibration
In the traditional approach, many, many photodetector signals arescanned off of the sensing plane and then transferred to a PC forsignal processing
Surface Plasmon Resonance Signal Processing:
(Fully) Integrated Approach
In the first fully integrated approach, all signals are processed on thesensing (photodetection) plane using both current-mode and pulse-mode arithmetic operations.
MultivariateCalibration
Low ResolutionPhotodetection
“Flatlining”Current Scaling
Conversion toPulse Mode
Low ResolutionRegression
Software
Approach #3 (Pulse-Mode, Fully Integrated)
Surface Plasmon Resonance Signal Processing:
(Fully) Integrated Approach
In the second fully integrated approach, all signals are processed onthe sensing (photodetection) plane using current-mode arithmeticoperations which significantly reduces circuit size and complexity.
MultivariateCalibration
Low ResolutionPhotodetection
Dark CurrentCompensation
“Flatlining”Current Scaling
Low ResolutionRegression
Software
Approach #4 (Current-Mode, Fully Integrated)
Surface Plasmon Resonance Portable Systems: Do they work?
Idark
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Sp_0 Sp_1
6/6
6/6 6/9
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4/44/44/4
6/6
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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
6/6
Vi Vref
Approach #4
Approach #2
Approach #3
All (CMOS)Integrated approaches
are operational, asindividual circuits,
but how do theyperform in the
system?
Reduction in peripheral components without loss of performance in SPR-basedsystems can indeed be done by:
Surface Plasmon Resonance Creating System Portability:Can it be Done Effectively?
(c) Compressing thesignal processing toa single integratedcircuit (chip).
(a) Choosing a systemconfigurationamenable tominiaturization.
(b) Converting theoptical path fromdiscrete componentsto integrated fiberoptic components;
Surface Plasmon Resonance Output Generated by Portable Approach
Clearly Indicates point of Resonance
Air
Raw Data (background overwhelms resonance)Referenced Data (Resonance is evident)
Increasing RI
Surface Plasmon Resonance Comparable Performance is Achieved!
6.8 X 10-4
2.54%Current Mode
6.9 X 10-42 X 10-45 X 10-4RI Resolution2.72%3.53%6.07%Prediction Error
Pulse ModeVoltage ModeTraditionalApproach
200 X 1000FullCurrent Mode
200 X 1200FullPulse Mode
200 X 1800PartialVoltage Mode
BigNoneTraditional
Size(λ X λ )
Level ofIntegration
Approach
Surface Plasmon Resonance The Story of Portable Systems
National Science Foundation # ECS0300537
Pixel
AnalogSampling
DigitalControl
Phototransistor
The End
2mm