EM-Lens Enhanced Power Transfer and Multi-Node Data Transmission for Implantable Medical Devices

This paper presents a robust EM-lens-enhanced wireless power transmission system and a novel multiple-node data communication method for distributed implantable medical devices. The proposed techniques can solve the common issues caused by multiple implanted devices, such as low power transfer efficiency through biological tissues, uneven delivered power for distributed devices, interference between simultaneous wireless power and data transmission, and intermodulation distortion between various data channels. A prototype system has been designed and manufactured with discrete components on FR4 substrate as a proof of concept. The EM-Lens-enhanced inductive links can expand the power coverage of transmitting (Tx) coil from 9mm×5mm to 14mm×13mm, and double the recovered DC voltage from 1.8V to 3.2V at 12.5mm distance. Data communication is achieved by novel low-power backscatter-CDMA scheme. This permits transmission of data from several nodes all operating with the same carrier frequency simultaneously reflecting the power carriers to the primary side. In this paper, we demonstrate simultaneous communication between two nodes at 125kbps with 1.05mW power consumption.