Effects of Wireless Power Transfer on Capacitive Coupling Human Body Communication

The capsule endoscope is being integrated with various kinds of actuators and sensors to form a micromedical robot, and hence, it requires much more energy than before. Wireless power transfer (WPT) is promising to address the energy supply problem, but strictly restricted to keep safe. Human body communication (HBC), a low-power consumption method, can greatly reduce energy for communication. This paper, for the first time, combines HBC with WPT to investigate the possibility of their working together, and focuses on the effects of WPT on the communication effectiveness of HBC. Parameters for both HBC and WPT are set to be those widely studied or even clinically used. The frequencies and peak-peak voltages for HBC were selected as 3 MHz and 3.3 V, and WPT were adjusted from 0 kHz to 1.5 MHz and 0 to 400 V. On the one hand, HBC with fundamental sinusoidal wave was used to study the interaction. The simulation results accord well with the experimental results, and both of them indicate that the HBC signal can be accurately extracted based on IIR notch filter. On the other hand, HBC modulated by binary differential phase shift keying method was utilized. Groups of experiments were conducted, and the received signals were demodulated by improved polarity comparison method. Bit error rate was calculated to be zero in all the studied frequencies and voltages. Results indicate that HBC and WPT can cowork well when integrated in one capsule robot.