A Wireless Artificial Mechanoreceptor in 180-nm CMOS

Abstract

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 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . 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 μW in the OOK mode. The 1.62-mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> chip is fabricated in a standard 180-nm CMOS process and consumes 110.3 μW.