The Wireless Power Transmission on the Wrist-to-Forehead Path Based on the Body Channel

The body channel based wireless power transfer (BC-WPT) method utilizes the human body as the medium to transfer power for bioelectronics, which can achieve a lower transmission loss due to its higher conductivity. However, except for the channel length, different on-body locations of the transmitter and receiver also influence the power supply performance. This paper focuses on the wrist-to-forehead path to show the potential of BC-WPT for the brain bioelectronics such as the brain computer interface device. The channel characteristics from 10 MHz to 60 MHz are measured by a vector network analyzer (VNA) and a prototype BC-WPT system with different copper electrodes and the lowest power loss locates between –22 dB and –33 dB. Furthermore, the minimum path loss limit is simulated in Advanced Design System (ADS) software and the lowest optimum path loss can reach nearly –13 dB. Finally, a rectifier circuit is also built at the receiver side to harvest d.c. voltage. The results show that the open-circuit voltage (OCV) can reach 1.75 V with the transmitter of 50 \textΩ output impedance supplying 5 V_\rmpp sine voltage at 60 MHz when adopting 1 cm-diameter circular electrodes.