A miniaturized and biocompatible dual-band implantable antenna for fully-passive wireless signal monitoring

This study proposes a novel-shape, dual-band, and miniaturized antenna suitable for microwave backscattering that can receive the signal from an external device at 2.4 GHz and reflect sensed signals at 4.8 GHz. The antenna consists of a rectangular patch with coaxial feed and miniaturizing is achieved without using shorting pins and slots in the ground plane. The proposed antenna has a compact size of 8.5 x 8.5 x 1.27 mm3. The results were verified by CST software in both heterogeneous multi-layer (skin, fat, and muscle) and homogenous single-layer (skin, muscle, stomach, small intestine, and colon) human tissue phantoms. To diagnose the effects of fabrication tolerance and dimensions of designing sections on impedance and bandwidth, the antenna is parametrically analyzed. For EM radiation effects on the human body and safety considerations, the specific absorption rate (SAR) of the antenna has been analyzed. In addition, the performance of the proposed antenna is evaluated experimentally using a muscle mimicking liquid. The proposed compact size antenna exhibits dual-band characteristics (2.4/4.8 GHz), has a ground plane without any vias and slots, has a low SAR, and has sufficient gain value making it a proper and applicable choice for fully-passive implantable medical devices.