The Microbead: A Highly Miniaturized Wirelessly Powered Implantable Neural Stimulating System.

Area of Science:

• Biomedical Engineering
• Neuroscience
• Electrical Engineering

Background:

• Current neural implants face challenges in achieving spatially selective stimulation across diverse brain regions and depths.
• A need exists for miniaturized, wirelessly powered devices capable of precise neural activation.

Purpose of the Study:

• To introduce and validate the
• microbead,
• a novel, fully integrated, wirelessly powered neural device for spatially selective neural tissue activation.
• To demonstrate the feasibility of the smallest remotely powered stimulator to date.

Main Methods:

• Fabrication of a prototype chip using 130-nm CMOS technology, measuring 200 μm × 200 μm.
• Experimental validation in a rat model, stimulating the sciatic nerve with 195-μs current pulses.
• Utilizing a highly optimized transmitter (Tx) coil with 36-dBm source power at a 5 mm coupling distance.
• Implementation of a pulsed powering scheme to reduce average transmitted power for human safety.

Main Results:

• Successfully demonstrated the smallest remotely powered stimulator to date.
• Validated the device's functionality through in vivo stimulation of the sciatic nerve.
• Achieved significant reduction in average emitted power using a pulsed powering scheme.

Conclusions:

• The microbead represents a significant advancement in neural implant technology, offering unprecedented miniaturization and wireless power capabilities.
• The device enables spatially selective neural activation, addressing key limitations of existing technologies.
• The pulsed powering strategy ensures compliance with safety limits for potential human applications.