No abstract

A 0.8 mm 3 wireless, ultrasonically powered, freefloating neural recording implant is presented. The device is comprised only of a 0.25 mm 2 recording IC and a single piezoceramic resonator that is used for both power harvesting and data transmission. Uplink data transmission is performed by analog amplitude modulation of the ultrasound echo. Using a 1.78 MHz main carrier, >35 kbps/mote equivalent uplink data rate is achieved. A technique to linearize the echo amplitude modulation is introduced, resulting in <1.2% static nonlinearity of the received signal over a ±10 mV input range. The IC dissipates 37.7 µW, while the neural recording front-end consumes 4 µW and achieves a noise floor of 5.3 µVrms in a 5 kHz bandwidth. This work improves sub-mm recording mote depth by >2.5x, resulting in the highest measured depth/volume ratio by ∼3x. Orthogonal subcarrier modulation enables simultaneous operation of multiple implants, using a single-element ultrasound external transducer. Dual-mote simultaneous power up and data transmission is demonstrated at a rate of 7 kS/s at the depth of 50 mm.

We present a 6.5mm 3 , 10mg, wireless peripheral nerve stimulator. The stimulator is powered and controlled through ultrasound from an external transducer and utilizes a single 750x750x750µm 3 piezocrystal for downlink communication, powering, and readout, reducing implant volume and mass. An IC with 0.06mm 2 active circuit area, designed in TSMC 65nm LPCMOS process, converts harvested ultrasound to stimulation charge with a peak efficiency of 82%. A custom wireless protocol that does not require a clock or memory circuits reduces on-chip power to 4µW when not stimulating. The encapsulated stimulator was cuffed to the sciatic nerve of an anesthetized rodent and demonstrated full-scale nerve activation in vivo. We achieve a highly efficient and temporally precise wireless peripheral nerve stimulator that is the smallest and lightest to our knowledge.

No abstract

No abstract