Deformation Sensitivity Study of Embroidered UHF RFID Antennas

Textile-based antennas that can be embroidered directly onto cloth fabrics have shown great potential for wearable applications. However, the performance of the embroidered antennas are significantly affected by the materials used, as well as the geometrical variations and deformations. In this paper, we analyze several factors that affect the performance of embroidered antennas, including the choice of geometry, the bending and elongation of tags, as well as the resistivity of the yarns for embroidery. Modeling, simulation, and measurement have verified our analysis and demonstrated that slotted-patch UHF RFID antennas fabricated with low resistance yarns are more sensitive to geometrical variations, such as bending and curving. RFID tags equipped with this embroidered antenna can be utilized as a battery-less passive deformation sensor for human movements.