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

Robust, wearable, on-body antenna relying on half mode substrate integrated waveguide techniques

A compact, robust, wearable antenna for body-worn applications in the 2.4 GHz Industrial Medical and Scientific band is designed, fabricated and tested. This novel compact textile cavity backed slot antenna combines a half-mode substrate integrated waveguide topology with an additional row of shorting vias for miniaturization. Excellent free space performance is achieved with a measured 4.6 % impedance bandwidth, maximal gain of 4.7 dBi and radiation efficiency of 81.3 %. On-body measurements reveal minimal frequency detuning when the antenna is worn by a test subject as well as a negligible impedance bandwidth reduction to 4.5 %. The low calculated Specific Absorption Rate of 0.51 W/kg averaged over 1 g of tissue demonstrates high antenna body isolation. Therefore, this design is an attractive option as antenna in smart textile systems

The relation between SAR and the electromagnetic field distribution for heterogeneous exposure conditions

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Wearable, small, and robust: the circular quarter-mode textile antenna

A miniaturized wearable antenna, entirely implemented in textile materials, is proposed that relies on a quarter-mode substrate integrated waveguide topology. The design combines compact dimensions with high body-antenna isolation, making it excellently suited for off-body communication in wearable electronics/smart textile applications. The fabricated antenna achieves stable on-body performance. A measured on-body impedance matching bandwidth of 5.1% is obtained, versus 4.8% in free space. The antenna gain equals 3.8 dBi in the on-body and 4.2 dBi for the free-space scenario. High radiation efficiency, measured to be 81% in free space, is combined with a low calculated specific absorption rate of 0.45 mW/g, averaged over 1 g of tissue, with 500 mW input power

An active wearable dual-band antenna for GPS and Iridium satellite phone deployed in a rescue worker garment

An active wearable dual-band circularly polarized microstrip patch antenna for Global Positioning System and Iridium satellite phone applications is presented. It is constructed using flexible foam and fabric substrates, combined with copper-on-polyimide film conductors. A low-noise amplifier chip is integrated directly underneath the antenna patch. The antenna's performance is examined under bending and on-body conditions. The active antenna gain is higher than 25 dBi and the 3dB axial ratio bandwidth exceeds 183 MHz in free-space conditions. The antenna performance is robust to bending and on-body placement