1. Distributed Microsystems Laboratory Paddlefish-Inspired 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)

2. Distributed Microsystems Laboratory Paddlefish-Inspired 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.

3. Distributed Microsystems Laboratory Paddlefish-Inspired Electroreception System Block Diagram Electroreceptor Input Signal Peak Gradient PSD Detector Bandpass Filter (  c ~ 5Hz) Afferent Oscillator X AA Mixer OUT Low-Pass Filter Epithelial Oscillator X Lock-in Amplification Electronic Gain Control EE Stage 1Stage 2

4. Distributed Microsystems Laboratory Paddlefish-Inspired 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.

5. Distributed Microsystems Laboratory Paddlefish-Inspired Electroreception System 5 Hz No Noise 5 Hz Noise = Signal Experimental Results (Preliminary, Stage 1): Signal Detectable at magnitudes down to 0.5*noise level

6. Distributed Microsystems Laboratory Paddlefish-Inspired Electroreception System Experimental Results (Preliminary, Stage 1): Signal Detectable at magnitudes down to 0.5*noise level 5 Hz Noise = 2*signal 5 Hz Noise = 5*signal