Flexible Antenna with AMC Backing for Non-Invasive Blood Glucose Monitoring

This study discusses the design of a non-implantable and flexible antenna for blood glucose level (BGL) monitoring purposes. In this work, a sensor consisting a circular shaped patch antenna divided in four sectors with a volume of, 56.5 mm x 30 mm x 0.16 mm, and a beehive inspired, artificial magnetic conductor (AMC) metasurface both operating in ISM band, is proposed. The proposed antenna has a reduced and defected ground plane. The antenna is simulated in CST MWS’23 and the reflection parameter (S11), gain, and bandwidth of the antenna are -42 dB, 2.54 dBi, 3.7 GHz respectively. Bend Test is carried out using the simulator for validating conformability of the proposed antenna. The beehive metasurface unit cell of dimensions 23 mm x 37 mm is designed as an AMC. The antenna is then, backed by the 3 x 3 AMC which acts as a ground plane of the antenna. After optimizing the distance between CDRA and metasurface to 3 mm, the gain is improved to 8.09 dBi. The antenna is tested with a three layer bio mimic human phantom and SAR is simulated. The antenna showed a permissible value of SAR as 0.00812 W/kg. For BGL monitoring, the antenna is simulated and analysed for different BGL values. For this purpose, the Debye Model is referred for extracting dielectric properties of human blood for different glucose levels. The designed sensor is small, robust, low cost and easy to fabricate which favours BGL monitoring.