Distributed Microsystems Laboratory Paddlefish-Inspired Electroreception System

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Distributed Microsystems LaboratoryPaddlefish-In
spired Electroreception System

• Research Objective
• To design, simulate, and fabricate an integrated
  sensing system for detecting electric field
  fluctuations of small magnitude and low
  frequencies in cluttered (liquid) background
  media
• Sensor Candidates (Potential Collaborations)
• Electrochemical Ag/AgCl Electrodes
• Advanced Physics Lab, University of Washington
  (UW)
• Optical Micro-ring resonators
• MDITR Science and Technology Center (UW-led)

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Distributed Microsystems LaboratoryPaddlefish-In
spired Electroreception System

• Basic Model (5Hz sample signal of interest)
• Stage 1
• Receives sensor (electric field) input
• Preserves 5Hz from much lower/higher frequencies
• Preserves narrow-band signal (attenuates
  broadband)
• Detects 5Hz signal in noisy environments
• Stage 2
• Coupled oscillators lock-in to 5Hz signal
• Lock-in attenuated or diminished by gradient in
  electric field (wrong direction of motion) or by
  particular orientations assists in localization
• Stage 3
• Coupling (local) between Stage 1/Stage 2 cells
• More complex discrimination and signal processing.

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Distributed Microsystems LaboratoryPaddlefish-In
spired Electroreception System
Block Diagram
wA
Afferent Oscillator
X
Electroreceptor Input Signal
Bandpass Filter (wc 5Hz)
Mixer
OUT
X
Lock-in Amplification
Stage 1
Stage 2
wE
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Distributed Microsystems LaboratoryPaddlefish-In
spired Electroreception System

• Block Diagram Explanation of Terms and Function
• Electroreceptor Input Signal Generated by a
  Sensor Candidates (in Array)
• Band-pass filter low-order pre-filter for input
  signal (around 5Hz)
• Afferent oscillator (around 56Hz in paddlefish)
• variable frequency voltage-controlled oscillator
• Frequency shift occurs in response to
• Electric field gradient (source moving toward or
  away from sensor)
• Electric field orientation
• Epithelial oscillator (around 25 Hz in
  paddlefish) fixed reference
• Lock-in amplification attenuates or eliminates
  oscillation when afferent oscillator cannot
  lock -- indicating gradient or orientation
  information
• Gain-control increases afferent carrier
  proportion to degree of lock in
• Multiple cells (block diagram) can be coupled for
  higher order tasks.

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Distributed Microsystems LaboratoryPaddlefish-In
spired Electroreception System
Experimental Results (Preliminary, Stage 1)
Signal Detectable at magnitudes down to
0.5noise level
5 Hz No Noise
5 Hz Noise Signal
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Distributed Microsystems LaboratoryPaddlefish-In
spired Electroreception System
Experimental Results (Preliminary, Stage 1)
Signal Detectable at magnitudes down to
0.5noise level
5 Hz Noise 2signal
5 Hz Noise 5signal