A Feed-through Sharing Structure of a Wireless Power Transfer Coil and Stimulation Electrodes for Implantable Medical Devices

We present a combined structure of a wireless power transfer (WPT) coil and stimulation electrodes for implantable medical devices. This structure has only a pair of wire connections, and the coil and electrodes are connected to circuits through a shared pair of feed-throughs. It reduces the number of feed-through connections from 4 to 2 and improves hermetical sealing capacity and fabrication complexity. A $21 \times 19$ mm sized 2-turn coil is fabricated and measured with platinum electrodes of 1-cm diameter in a saline solution. The performance degradation of the wireless power efficiency is 2.2%. Stimulation voltage drop and current consumption increase are 2.5% and 3.1%, respectively. With a stimulation and WPT circuit module, wirelessly powered stimulation waveforms are verified.