Wearable Chipless RFID Sensor Based on Complementary Split Ring Resonator for Body Temperature Monitoring

This paper presents the design and fabrication of two wearable chipless RFID tag antennas with unique identification codes 10101 and 11111. Each antenna utilizes a circular patch with a split ring resonator, where a specific number and arrangement of slots enable distinct tag identification. Shieldit Super fabric is employed as the radiating element, with felt material serving as the substrate. The antennas operate across a frequency range of 1–3 GHz, and bending analysis indicates reliable performance up to a 60° bend along both X- and Y-axes. Experimental tests on the fabricated antennas revealed sensitivity to environmental factors, with noticeable changes in S<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</inf> as temperature varied, highlighting the antenna’s responsiveness to thermal fluctuations. These findings support the potential of these designs for robust, flexible, and responsive wearable RFID applications.