Transcutaneous capacitive wireless power transfer (C-WPT) for biomedical implants

This paper reports on the implementation of a transcutaneous capacitive wireless power transfer (C-WPT) strategy for biomedical implants. The approach is based upon a series resonant converter in which the tank capacitors are replaced with a capacitive link comprising two pairs of coated parallel plates aligned around the tissue as the dielectric material. Miniaturized printed-circuit boards are developed that incorporate all requisite circuitry on the front-side of transmitter (TX) and receiver (RX) plates, as well as 400mm
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Parylene-N-coated pads on the back-side of the plates. With two 100μH inductors in series with the capacitive link, a resonance frequency of ~151kHz is measured for both series resonant tanks. The system is designed to operate above resonance at 210kHz in zero-voltage switching (ZVS) regime to minimize switch conduction losses and increase the power transfer efficiency (PTE). In experimental verification, ~ 59 to 290mW is delivered to the implant (secondary) side through 5mm-thick shoulder beef with measured PTE of >31%. A peak PTE of ~38.4% is also measured when delivering 105.5mW from a dc source of 11V on the external (primary) side.