A single-channel implantable microstimulator for functional neuromuscular stimulation

Area of Science:

• Biomedical Engineering
• Neuroprosthetics

Background:

• Functional neuromuscular stimulation (FNS) aims to restore function in paralyzed muscles.
• Existing FNS systems often require bulky external hardware or invasive wiring.
• A need exists for minimally invasive, wirelessly powered microstimulators for targeted muscle activation.

Purpose of the Study:

• To describe the design and function of a novel single-channel implantable microstimulator for FNS.
• To demonstrate the feasibility of wireless power and data transmission for controlling microstimulators.
• To evaluate the performance of the microstimulator in delivering electrical stimulation to paralyzed muscles.

Main Methods:

• A miniaturized (2 x 2 x 10 mm3) implantable microstimulator was developed.
• Radio frequency (RF) telemetry was employed for wireless power and data transmission using a 2-MHz carrier.
• A bi-CMOS receiver circuit managed power, clock recovery, address decoding, and stimulation delivery.
• A thin-film iridium-oxide electrode delivered charge to the target muscle.

Main Results:

• The microstimulator is insertable via a hypodermic needle.
• Wireless power and data transmission enabled selection of individual microstimulators via a 5-bit address.
• The device delivered up to 2 microC of charge with a 10 mA current for 200 microseconds into < 800 omega loads.
• Receiver circuitry achieved power dissipation of 45-55 mW.

Conclusions:

• A single-channel implantable microstimulator for FNS has been successfully developed.
• Wireless RF telemetry provides a viable method for powering and controlling such devices.
• This technology offers a promising, minimally invasive approach for restoring neuromuscular function.