Investigations in Deep Brain Stimulation: Neurostimulating Electrodes March 9, 2001 Tom Chiesl, Eric Faulring, Elizabeth Nunamaker, Jonathan Yuen

Parkinson’s Disease Progressive central nervous system disorder Degeneration of pigmented neurons of the Substantia Nigra Men and women over fifty Inability to control muscular activity Gait difficulty Rigidity Tremor

Traditional Treatment Options Drugs (Levodopa) Initial reduction of symptoms Tolerance develops over time Pallidotomy Thalamotomy

Emerging Treatment Options Deep Brain Stimulation (DBS) Placement of electrode within thalamus Periodic stimulation overrides faulty signals Intensity / Frequency adjusted as needed

Medtronics Production Electrode Voltage (V) 3.07    1.1 Frequency (Hz)    23.5 Pulse Width (  sec)    Months 6 Months 12 Months

Biological Requirements of Bio-Electrodes Size Non-toxic Non-inflammatory / non-immunogenic Bio-fouling

Engineering Requirements of Bio-Electrodes Corrosion Resistance Packaging (Control, Power, Communication) Manufacturing Complexity / Cost Component Materials Compatibility Functionality (Maintenance, Adjustments)

Recording Electrode - Large Capacitance Stimulating Electrode - Small Resistance High Surface Area (Minimize Electrical Impedance) Gas Evolution (Safe Charge Density Injection Limit) Electrical Requirements Bio-Electrodes

Emerging Fabrication Technologies – Doping electrode tracings onto silicon substrate Evaporative metal deposition on micro-injection molded plastic substrate Polycrystalline silicon tracings Current Fabrication Technologies – Macroscale production (Au, Pt electrodes) CMOS processing Photolithography

Emerging Fabrication Technologies - Evaporative metal deposition on micro-injection molded plastic substrate

Emerging Fabrication Technologies - Doping electrode tracings onto silicon substrate Quadripolar Electrode Etched holes for neural growth factor and nerve in-growth

Summary Use thin film CMOS technology incorporating polycrystaline electrodes or doped silicon electrodes Electrodes are microscale More electrodes for increased stimulation options Closed loop – feedback control Less destructive to neural tissue

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