Implanted Antennas and RF Transmission in Through-Body Communications

This chapter focuses on radio frequency (RF) transmission characterization as well as the antenna designs for wireless capsule endoscopy and neural motor prosthetic devices. It reviews the key issues of RF or microwave signal propagation through body/head and implanted/external antennas of implanted medical devices. The key performances of the implanted/external antennas such as the impedance matching and antenna efficiency are affected by the lossy, inhomogeneous, and dispersive surrounding tissues. The chapter shows that the co-design of antenna with its surrounding tissues and biocompatible casing is needed in order to achieve optimum efficiency. It shows that to reduce the specific absorption rate (SAR) and enhance the transmission with the external receiver, an antenna with directional radiation is preferred. The system consists of three 32-channel implantable probe units for neural signal acquisition, a wearable head unit for neural signal acquisition, wireless telemetry, and wireless power transfer as well as an external base station.