The Development of Capacitive Power Transfer for Biomedical Implantable Devices

Abstract

Wireless power transfer using electric and magnetic near-fields has been used in many applications widely, and biomedical implants being one of them. The most commonly used method for powering power wirelessly to biomedical implantable device is using inductive coupling between two mutually-coupled coils. In this paper, a consider new method will be proposed in transferring power for biomedical device which is based on capacitive coupling and known as capacitive power transfer (CPT) system. The main reasons of using this method are the low electromagnetic interference (EMI), can reduce power losses and the abilities to transfer power across metal barriers compared to inductive power transfer. To be specific, in this work, we have designed Class E circuit as an inverter to convert the 12VDC to AC with 1 MHz frequency. The prototype of the capacitive power transfer for implantable application has also been successfully developed with capacitive plate dimensions of 3cmx3cm width per length for receiver plate and 4cmx4cm for transmitter plate, respectively. 5mm thickness of beef separation between the plates is used in this paper. The design specification of this work is accordance to stimulator for peripheral nerve implantable device which only needs 100 mW of power to operate in the CPT system. Overall, the developed CPT system for the biomedical device is able to deliver 76mWatt with 41.43% efficiency. To enhance the efficiency, the impedance matching circuit has been proposed in this work and the prototype is now able to deliver 140mWatt power to the DC load, achieving zero voltage switching (ZVS) waveform and efficiency of 77.5%.