Miniature fully-passive brain implant for wireless real-time neuropotential monitoring

We present a 8.7 mm × 10 mm fully-passive brain implant transceiver, capable of neuropotential acquisition as low as 20 μVpp. This high sensitivity wireless implant implies that, for the first time, most neuropotentials generated by the human brain can be read in a wireless and fully-passive manner. Concurrently, the proposed implant is 63% smaller than previously reported fully-passive neurorecorders. The neuropotential recording system consists of the brain implant and an exterior interrogator. Unique aspects of our design include: a) an Anti-Parallel Diode Pair (APDP) mixer within the implant for efficient harmonic mixing, and b) a set of highly-coupled miniature implanted and exterior antennas. This leads to >30 dB sensitivity improvement over previous implants. Overall, this is a game-changing capability for studying several conditions (epilepsy, tremor, addictions, etc.).