Exploiting Embroidered UHF RFID Antennas as Deformation Sensors

Abstract

Textile-based antennas that can be embroidered directly onto cloth fabrics have shown great potentials for wearable applications. However, the performance of the embroidered antennas is significantly affected by the materials used, as well as the antenna's geometrical variations and deformations caused by human activities. In this article, we analyze several factors that affect the performance of embroidered antennas, including the choice of geometry, the bending and elongation of fabric substrate, as well as the resistivity of the yarns used for embroidery. Modeling, simulation, and measurement results 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, while meander line dipole (MLD) antennas are more sensitive to stretching and elongation. RFID tags equipped with these embroidered antennas can be utilized as battery-less passive deformation sensors for human movements.