Liquid metal-based on cotton/lycra elastic fabric surface for flexible antenna and wearable strain sensor

Textile-based wearable electronics have drawn increasing attention in recent years, but stable and durable conductive mechanism on textiles has been the challenge. In this study, we propose to fabricate a liquid metal circuit on textile substrates for flexible antennas and wearable sensors via screen printing method. The breakage of liquid metal circuit on cotton/lycra elastic fabrics can be repaired by pressing or heating, and the patterned liquid metal circuits can be removed using sodium hydroxide solution. Furthermore, the liquid metal circuit was designed as a pressure switch for thermal management system with the temperature precisely controllable by tuning the applied pressure. The liquid metal circuit was further designed as a flexible near field communication (NFC) antenna, providing identification capacity such as replacing campus card and protecting children. The maximum bending angle and effective distance of the NFC tag are determined to be 150 and 17.8 mm, respectively. In addition, the as-prepared liquid metal-based fabric sensors can accurately human motion detection in real time, exhibiting great potential in flexible wearable electronics.