Evaluation of Polypyrrole-Coated Conductive Yarn for eTextile Applications - Embroidered RFID Antennas

This paper presents a comparison of Polypyrrole (PPy)-coated conductive yarn and traditional silver-based conductive yarn in terms of electrical and mechanical properties. Next, the paper describes fabrication and measurement of passive ultrahigh frequency (UHF) radiofrequency identification (RFID) tag antennas fabricated from the two conductive yarns. The resistance of the PPy yarn was measured to be 0.3 MΩ/m, which is significantly higher than the resistance of the silver-based yarn (500 Ω/m). The tenacity of the PPy-based yarn was measured to be 42.7 cN/tex, which is more than twice that of the silver-based yarn (20.5 cN/tex). The peak read ranges achieved by the PPy-based RFID tags were around 1.5 meters in European and US center frequencies, while the peak read ranges of the silver-based tags were slightly below 4 and 5 meters at the European and US frequencies, respectively. Despite the PPy's shorter read ranges, the results are promising, as they indicate high potential of PPy-based yarns especially in mechanically demanding eTextile applications. As PPy yarn has a significantly lower environmental footprint compared to the silver-based yarn, the possibilities should definitely be studied further in the eTextile field.