Electromagnetic Field Analysis of Signal Transmission Path and Electrode Contact Conditions in Human Body Communication

Kentaro Yamamoto,Yoshifumi Nishida,Fukuro Koshiji,Dairoku Muramatsu,Ken Sasaki

doi:10.3390/app8091539

Kentaro Yamamoto, Yoshifumi Nishida + Show 3 more

Open Access

https://doi.org/10.3390/app8091539

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Abstract

Human body communication (HBC) is a wireless communication method that uses the human body as part of the transmission medium. Electrodes are used instead of antennas, and the signal is transmitted by the electric current through the human body and by the capacitive coupling outside the human body. In this study, direction of electric field lines and direction of electric current through the human body were analyzed by the finite-difference time-domain method to clarify the signal path, which is not readily apparent from electric field strength distribution. Signal transmission from a transmitter on the subject’s wrist to an off-body receiver touched by the subject was analyzed for two types of transmitter electrode settings. When both the signal and ground electrodes were put in contact with the human body, the major return path consisted of capacitive coupling between the receiver ground and the human body, and the electric current through the human body that flowed back to the ground electrode of the transmitter. When the ground electrode was floating, the only return path was through the capacitive coupling of the floating ground. These results contribute to the better understanding of signal transmission mechanism of HBC and will be useful for developing HBC applications.

Highlights

Human body communication (HBC) is a wireless communication method that uses the human body as part of the signal transmission medium, and it is expected to be among the technologies used in wireless body area networks [1]
Thestrength case of the two-electrode transmitter, current flowed and electric current in the human body were compared for one-electrode transmitter and from the torso, through the upper arm, and to the ground electrode of the transmitter that was in two-electrode transmitter
The signal andbetween ground electrodes ofground the transmitter in contact contact with the arm

Summary

Introduction

Human body communication (HBC) is a wireless communication method that uses the human body as part of the signal transmission medium, and it is expected to be among the technologies used in wireless body area networks [1]. In the IEEE (Institute of Electrical and Electronics Engineers) 802.15.6 standard, HBC was adopted as one of the three physical layers for the body area network. In comparison with other wireless communication technologies such as Bluetooth and Zigbee, HBC is advantageous in terms of its communication secrecy, low power consumption, and intuitive tactile operation. Because of these advantages, HBC is expected to be utilized in wearable devices for health care systems [3]. In galvanic HBC, the signal frequency is between 100 kHz and 10 MHz and the current flowing through the human body between the

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Conclusion