A study of wireless power transfer for implantable devices by using wearable devices

Wireless power transfer (WPT) is an effective method for power supply from wearable devices to implantable devices (IMDs). To reduce the IMD size, the received coil can be integrated with other functional circuits, whereas the efficiency is low if the traditional inductively coupled method is used. In this paper, limiting factors of the WPT efficiency including the quality factor of coils and the coupling coefficient are analyzed. A circuit model of magnetic resonance coupled (MRC) WPT is established and simplified for this application. It shows that the MRC method is feasible to improve the efficiency for IMD.