In this paper, we present an ultrasonically controlled switching system that can save the battery power for implantable devices by turning the system on and off, on-demand. Ultrasonic control is employed to reduce the device size, increase the penetration depth, and reduce misalignment sensitivity associated with alternative techniques using permanent magnet and RF signal. As a proof-of-concept demonstration, a 665 kHz ultrasonic signal is used to activate a piezoelectric receiver which in turn switches a battery-powered RF system on-and-off. In-vitro tests show a reliable switching functionality at distances of up to 8 cm while consuming 43.5 nW (14.5 nA current consumption with 3 V power supply) when the system is in off-state, a factor of 10–100 times lower than the sleep-mode power consumption of typical RF SoC systems. The dimension of fabricated prototype is 6.3 × 16.7 × 2‍ mm3 allowing it to be easily incorporated into many existing implantable devices.
