Investigations in Deep Brain Stimulation:

Neurostimulating Electrodes

March 9, 2001March 9, 2001

Tom Chiesl, Eric Faulring, Tom Chiesl, Eric Faulring,

Elizabeth Nunamaker, Jonathan YuenElizabeth 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 1.2 3.30 1.1 3.38 1.1

Frequency (Hz) 158.1 29.1160.6 29.0 165.6 23.5

Pulse Width (sec) 107.0 47.6 105.041.5 117.5 80.8

3 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

Questions