An Ultrasonically Controlled Power Management System for Implantable Biomedical Devices

In this paper, we introduce an ultrasonically controlled power management system that can turn a battery-powered implantable device on or off on-demand, hence, saving valuable energy resources. Ultrasonic control is employed to reduce the device size and increase the penetration depth. A rapid-prototyping laser-assisted circuit printing method is also introduced in order to reduce the fabrication cost and size of the ultrasonic control module. As a proof-of-concept demonstration, a 672 kHz ultrasonic signal is used to activate a piezoelectric receiver, which in turn switches a battery-powered system on-and-off. In-vitro tests show a reliable switching functionality at distances of up to 6.7 cm at 46 mW/cm(2) acoustic input power while consuming 0.15 mu A when the system is off, a factor of 10-100 times lower than the sleep-mode power consumption of typical RF SoC systems. The dimensions of the receiver prototype is 0.8 x 1.6 x 0.2 cm(3) allowing it to be easily incorporated into many existing implantable devices.