Transcript Investigations in Deep Brain Stimulation: Neurostimulating

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
3 Months
6 Months
12 Months
Voltage (V)
3.07  1.2
3.30  1.1
3.38  1.1
Frequency (Hz)
158.1  29.1
160.6  29.0
165.6 23.5
Pulse Width (sec)
107.0  47.6
105.041.5
117.5  80.8
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)
Electrical Requirements Bio-Electrodes
• Recording Electrode - Large Capacitance
• Stimulating Electrode - Small Resistance
• High Surface Area (Minimize Electrical Impedance)
• Gas Evolution (Safe Charge Density Injection Limit)
Current Fabrication Technologies –
• Macroscale production (Au, Pt electrodes)
• CMOS processing
• Photolithography
Emerging Fabrication Technologies –
• Doping electrode tracings onto silicon substrate
• Evaporative metal deposition on micro-injection molded
plastic substrate
• Polycrystalline silicon tracings
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