Team 3 Wireless Rat Stimulation

1
Team 3Wireless Rat Stimulation

• Justin Horowitz
• Tom Richner
• Anne Wilson
• Mentor Dan Moran

Delivered September 19, 2007
2
Background Limitations of Previous Design

• Matt MacEwans design
• Mechanical mismatch
• Tissue damage
• Device damage
• Recovery issues
• Animal Studies restrictions
• Only one recording opportunity
• Production cost/inconsistency

3
Project Scope

• Inside
• Implantable wireless nerve stimulator
• Power
• Signal receiver and processor
• Materials
• Layout and fabrication
• External controller
• Control scheme
• Signal transmission method

• Outside
• Prototype
• Surgical procedure
• Animal experimentation
• Data acquisition and analysis

4
Design Requirements (Metrics)
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Existing Solution BION

• Features
• Small, implantable
• Wireless
• Powered by mutual inductance
• Limitations
• not a conduit
• single channel

Patent 5193539 Issued March 16,
1993 Inventors JH Schulman, GE Loeb, JC Gord, P
Strojnik Assignee Alfred E. Mann Foundation (USC)
Figure from http//ami.usc.edu/projects/bion/
accessed on 9/18/07
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Existing Solution another microstimulator

• Features
• Small, implantable
• Wireless
• Powered by mutual inductance
• Silicon substrate, glass cap
• Limitations
• Single channel (electrodes in parallel)
• Not a conduit

Patent 5,314,458 Issued May 24,
1994 Inventors K Najafi, KD Wise Assignee
University of Michigan
Figure from US patent 5,314,458
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Existing Solution Sieve Electrode Array

• Features
• Array of holes with electrodes (multiple
  channels)
• Conduit
• Silicon fabrication
• Limitation
• Wired

Published in 94, 97 T Akin, K Najafi, K Smoke,
and R Bradley of the University of Michigan
Figure from Bradley RM, Xianghui C, Akin T, and
Najafi K. Long term chronic recordings from
peripheral sensory fibers using a sieve electrode
array. Journal of Neuroscience Methods. 74
(1997)179
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Preliminary Analyses

• Power supply issues
• How much do we need? 10µA 3 V 30 µW
• How hot does it get? How hot can it get? 115
  µW/mg protein in tissue is normal
• Capacitor size to deliver __ shocks
• QCV,
• Each channel needs to deliver 15 µA for 1 ms,
  therefore 15 picoCoulombs total charge
• 15 pCoul C 3 V, therefore each channel needs
  C 5 picoFarads

9
Current Organization of Team Responsibilities

• Justin
• Make this presentation
• Schedule
• Design calculations and simulations
• Anne
• Organization
• Literature searching
• Tom
• Patent-related activities
• Literature searching
• All
• Start producing design alternatives

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Design Schedule

• September 19
• Deliver this report
• September 20-October 1
• Compile preliminary report
• Finalize design requirements and their relative
  weighting
• October 1-16
• Produce a variety of design alternatives
• October 16-22
• Choose among the alternatives and produce reports
  detailing the alternatives and our selection
  process
• October 23-November 28
• Produce our final design and report on the process