Power management of miniature implantable device systems

Power management for miniature implantable device systems experiences challenges in mitigating conflicting design criteria, which include efficiency, maximum delivered power, and area of the implanted device. Conventional, battery-based methods of implantable device powering involve several fundamental limitations in practical use. Firstly, limited battery life necessitates additional replacement surgery. Secondly, batteries exhibit power density limitations, which implies the use of large, bulky power supplies only to match the peak power of an implanted system. Supercapacitors offer an attractive alternative for powering in an implantable setting due to their instantaneous recharging capability and longevity of up to 1 million cycles. Leveraging such a storage technology to replace batteries allows for significant breakthroughs in the implantable medical device space, including obviating the need for replacement surgery and elimination of safety concerns associated with toxic metal materials. The design challenges of equivalent series resistance (ESR) and breakdown voltage of supercapacitors create the need for an optimization of the power management of supercapacitively powered implantable devices, which are recharged via wireless powering. Optimization of this power management is conducted using genetic algorithms, which provide the basis for powering system design and a greater than 70% increase in the ratio of output power to inductance of state-of-the-art boost converters in an energy harvesting application. This work presents genetic algorithm based power management design that leverages flexible, solid-state supercapacitors and wireless energy harvesting, which is demonstrated in a subcutaneous telemetry application