Slenderly and conformable passive UHF RFID yarn

Abstract

This paper introduces an important innovation in the use, form factor and performance of passive Radio Frequency Identification (RFID) tags. An EPC Class 1 Gen 2 passive RFID tag is conceived in the form of a slenderly yarn. The wide-band and high gain tag antenna design is based on a resourceful impedance matching technique that keeps the slenderly form factor. In addition, a method to assure a reliable antenna-chip electrical contact based on modifying the package of existing RFID chips is presented. Antenna and chip geometry allow the tags to be cascaded in series and to compose a continuous yarn. A slenderly tag presents a diameter of less than 600 µm and reaches 14 m read range from 800 MHz to 920 MHz. Results are validated by theoretical studies, simulations and experimentations. The produced yam can follow different finishing process such as plastic coating to easily conform complex surfaces or textile wrapping and being used as primary raw in fabrics. To the authors knowledge, none of the traditional RFID inlays exhibit similar performance and shape conformability.