Study on intra-body communication for wearable devices

Abstract

Intra-body communication by sending very weak electrical current through the human body is studied. Electrical impedance of human body is several kilo hundreds ohm for frequency below 100Hz, and decrease down to several hundreds ohm for over 100kHz. Size and material of the electrodes effect the impedance at low frequencies, but the effect is negligible for transmission using frequencies over several hundreds kHz. Transmission is possible by attaching two electrodes of both transmitter and receiver. This does not form a closed loop circuit including the human body. Transmission efficiency peaks at around 5MHz. We have succeeded in transmitting electrocardiogram signal by using commercial FM modulator/demodulator devices for 10.7MHz.