Material Selection and Design Methods for Flexible RFID Tag Antenna

In recent years, advancements in flexible printed electronics have significantly propelled the development of wearable devices, especially in areas of integration, comfort, and streamlined manufacturing. By incorporating electronic components and conductive coatings onto flexible substrates, circuits gain enhanced flexibility and some degree of stretchability. Among these circuits, radio frequency identification (RFID) tag antennas have emerged as a focal point in wearable device communication due to their adaptability in power selection and their compatibility with printed circuit technologies. When designing flexible and stretchable RFID tag antennas using printed electronics, two critical factors need to be addressed. The first is the antenna’s structural design, which must account for varying environments and usage contexts. The second is the development of the antenna prototype, involving the selection of conductive coatings and flexible substrates, as well as the printing processes and performance evaluation standards. This paper will explore common conductive coatings and substrate materials used in flexible printed electronics, along with the design methods of printed tag antennas for wearable applications. Lastly, a novel approach is proposed in which the flexible and stretchable RFID tag antenna itself functions as a strain sensor for posture or pressure detection. Unlike conventional strain sensors, this design eliminates the need for additional communication modules, offering a simplified structure that can be easily printed onto clothing, thereby streamlining the production process.