Dual-Functional Wireless Power Transfer and Data Communication Design for Micromedical Implants

Smart microimplants are playing increasing roles in modern medicine. Wireless power transfer (WPT) and data communication are essential components in microimplants. In order to minimize device size, a preferred design is to share the wireless power channel with the data communication links consisting of a downlink and an uplink. While the implementation of the downlink is relatively easy, the uplink from the implant to the external unit is difficult to implement due to the limited power supply and small transceiver coil available within the implant. In this work, we present a new design of the data uplink that utilizes a special tapped coil and a simple passive circuit to produce a strong pulsed magnetic field (PMF) for signal emission. The strong PMF, which is oscillatory at the same resonant frequency as the WPT carrier, allows wireless data transmission over a longer distance through the WPT channel. Our new design is studied analytically, and the function of our circuit is confirmed by a computer simulation. A prototype is constructed, and its performance is compared with the existing load shift keying (LSK) method. Our experimental result showed that the design produced more than 15 times stronger signal strength at the receiving end.