On-Body Wearable Repeater as a Data Link Relay for In-Body Wireless Implants

Wireless medical devices implanted at different locations in the human body have a wide application range. Yet, high-data-rate communication in the 2.4-GHz Industrial, Scientific, and Medical band suffers from high in-body attenuation loss. Link improvement cannot be obtained by simply increasing transmit power, as battery life is limited and in-body absorption has to remain low. To overcome these problems, a flexible on-body textile patch antenna, robustly matched directly to the human body, is designed and developed as part of a wearable repeater, enhancing communication with implanted wireless devices. This receive antenna, which can cope with different morphologies and patient movements, enables reliable high data rate and low-power communication links with an implant. A data link measurement is performed for the on-body repeater system placed on the human torso, relaying the signals to nearby medical equipment, without wired connection to the patient. The performance of the data link is experimentally assessed in different measurement scenarios. For a repeater system relying on simple analog amplification, which is low-cost, energy-efficient, and can be fully integrated into clothing, excellent results are obtained, with an average measured signal-to-noise ratio of 33 dB for tissue depths up to 85 mm.