A Hybrid-Integrated Artificial Mechanoreceptor in 180nm CMOS

A low-power wireless chip for an implantable tactile sensor system is presented. The reported ASIC utilizes the low-loss magnetic human body communication channel for both wireless powering and data transfer. The chip is hybrid-integrated with an in-house fabricated MEMS capacitive force sensor to form an implantable artificial mechanoreceptor (IAM). An on-chip correlated double sampling capacitance-to-time converter consumes 3.9µW from a 1.2V on-chip regulated supply and achieves a resolution of 22.8fF over an input capacitance range of 100pF, while occupying an area of only 0.04mm2. A wireless power management feedback is used to ensure robust operation for different hand gestures and under process-voltage-temperature (PVT) variations. The IAM can operate in on-off keying (OOK) or frequency-shift keying (FSK) modulation formats, where the transmitter consumes only 15.6µW in OOK mode and is more immune to hand gesture variations in FSK mode. The 1.62mm2 chip is fabricated in a standard 180nm CMOS process and consumes 104.3µW.