A Wireless Artificial Mechanoreceptor in 180-nm CMOS

This article presents an implantable low-power wireless integrated system for tactile sensing applications. The reported application-specified integrated circuit (ASIC) uses a low-loss magnetic human body communication channel for both wireless power and data transfer. The chip is hybrid-integrated with an in-house fabricated MEMS capacitive force sensor to form an implantable artificial mechanoreceptor. An on-chip correlated double sampling capacitance to time converter (CTC) consumes 750 nW from a 1.2-V on-chip regulated supply, achieving a 2.0-fF resolution for an input capacitance of 14 pF and a FoM of 49 fJ/c-s while occupying an area of only 0.04 mm2. The CTC has a time-multiplexed mode to interface with four input capacitors. Wireless power management feedback is used to ensure robust operation in the presence of hand gesture changes and process–voltage–temperature variations. The on-chip data transmitter can operate in ON–OFF keying (OOK) or frequency-shift keying modulation formats, where it consumes only $7.8~\mu \text{W}$ in the OOK mode. The 1.62-mm2 chip is fabricated in a standard 180-nm CMOS process and consumes $110.3~\mu \text{W}$ .