The Microbead: A 0.009 mm³ Implantable Wireless Neural Stimulator

Area of Science:

• Neuroscience
• Biomedical Engineering
• Implantable Devices

Background:

• Current wirelessly powered neural implants often use microelectrode arrays.
• These arrays are limited by size, rigidity, and cortical coverage.
• Some applications require distributed neural interfaces rather than high channel counts.

Purpose of the Study:

• To develop a miniaturized, wirelessly powered stimulating implant.
• To enable distributed neural interfaces by detaching electrodes from a base.
• To optimize implant depth using novel coil design methods.

Main Methods:

• A novel electrode integration technique was used for miniaturization.
• Optimization design methods were applied to transmitter and receiver coils.
• The device was implemented in 130 nm CMOS technology (300 μm × 300 μm × 80 μm).

Main Results:

• A wirelessly powered, free-floating miniaturized implant was fabricated.
• The implant demonstrated wireless and stimulation capabilities in vitro and in vivo.
• The device achieved an excellent depth-to-volume ratio.

Conclusions:

• The free-floating miniaturized implant is a promising tool for minimally-invasive distributed neural interfaces.
• This technology could complement or replace current rigid electrode arrays.
• It offers a solution for large-scale, specifiable electrical stimulation and recording.