Design of disposable film-type capacitive wireless charging for implantable medical devices

This paper presents the design of capacitive wireless charging (CWC) for implantable medical devices using a film-type electrode. We clarify two points using a porcine skin with subcutaneous fat with a high affinity for the human body. One is the operational principle of CWC using a simplified equivalent circuit. The crucial parameters for the design are derived from a theoretical equation on maximum available efficiency, max. The other is to clarify the power transfer efficiency via CWC demonstration. The measured results showed that a max of 47.5% at 308 MHz could be achieved and a of RF-DC could reach about 23% at an input power of 70 mW. This study will enable implantable devices that can be charged during breaks or sleeping at home, and the patient burden will be greatly reduced.