A novel neuromorphic micro robotic neural probe Riley Zeller-Townson Haibo Zhao Date: 12/09/2008 MAE 589M Final Project

Project Overview Preformed literature Review Found gap in current technology Proposed design Proposed fabrication method for design

Background Many applications for reading neuron voltages (neuroprosthetics, stimulation)‏ Neurons pass electrochemical signals to each other Neurons connect using long, skinny extensions (axons and dendrites)‏

History Lesson Need to be able to monitor minute electric, chemical signals First experiments on squid giant axon (Cole, Hodgkin)‏ First real microelectrodes: hollow glass tubes Teflon coated microwires Michigan Probes, Utah Arrays, SOI

Current Work Biocompatibility –Surface coating –Flexibility –Probe geometry Microfluidics –Deliver and sample Signal quality

Problem Definition No design that physically resembles a neuron, though geometry a component of biocompatibility Electrodes should be placed like synapses on neuron Should be able to release chemical signals (contain microfluidic channels)‏

Electrodes/ microfluidics on arms (dendrites)‏ Arms can 'grow' into surrounding tissue Arms stored between concentric cyllinders

How it works Inner shaft acts as water main for all microfluidic channels, connects to each arm Drive actuators feed arms in and out Arms bend and rotate around inner shaft

Shuffle Drive Actuator

Actuator Dynamics EI (d 4 v(x))/(dx 4 ) – S(d 2 v(x)/dx 2 ) = 0 v = F e l 3 * (1 – cosh(k) – cosh(Kz) + zKsinh(K) + cosh(K(z-1)))/(EI 2 K 3 sinh(K))‏ d = 2 ∫ 0 1 √(1+(dv/dx) 2 )dx -2l y = F e l 3 / 24EI (3 * 1/2K-tanh(1/2K) / (1/2K) 3 )‏

Actuator Dynamics, cont Fe = ½ CV 2 /d Voltage = Q/A(d 1 /ε 1 + d 2 /ε 2 + d 3 /ε 3 )‏ Capacitance = Q/V = A/(d 1 /ε 1 + d 2 /ε 2 + d 3 /ε 3 )‏ Capacitance = ε 0 A/d 2 d = (1/2 to 3/5) * ε0A *½ V 2 /d 2 *l 3 /(24EI) (3 *( 1/2K-tanh(1/2K))/ (1/2K) 3 )‏

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Conclusions Completed design that should incorporate several biocompatibility techniques Created fabrication process for sophisticated probe design More modeling necessary Some more specific dimensions

Thank you for your time Any questions?