A Yagi-Uda Antenna as an Epidermal Strain Sensor

Advances in materials and production techniques create new design possibilities and applications for microwave sensors. In this work, the design of a Yagi-Uda antenna as a strain sensor for non-invasive muscle contraction detection is presented. To monitor epidermal strain, a highly flexible polyurethane substrate measuring 35 mm x 20 mm x 200 mu m is utilized. For a 10 % strain increase, the separation between the dipole elements increases by 0.1 mm. A 20 MHz shift in the resonant frequency of the antenna is observed for each 10 % step. The proposed Yagi-Uda antenna operates within the 2.4 GHz ISM band across strain values ranging from 0 % to 30 %.