Design, fabrication and applications of flexible RFID antennas based on printed electronic materials and technologies

The advancement of printed flexible electronics technology endows RFID tags with a simple fabrication process and innovative features such as flexibility, stretchability, and wearability. Flexible RFID tags based on printed flexible electronics technology are attracting considerable research interest. There are two main factors to consider when employing flexible printed electronics technology to create a flexible RFID tag antenna. One is the antenna structure design and the selection of conductive and flexible substrate materials, and the other is the fabrication of antenna prototypes and performance assessment that can satisfy specific demands. Both bring significant challenges to the materials, printing process, structural design and performance tuning of the antenna. Currently, most research is focused on the design and structure optimization of flexible RFID antennas, with just a few exceptions in inkjet printing based flexible electronics technology. Flexible antennas and printed flexible electronics technologies are yet to be efficiently combined, and systematic research and mutual development in terms of material selection, antenna design and simulation, prototype fabrication and measurement are yet to be achieved. Therefore, there is a strong need to do the research work in this field. This paper summarizes the current advances in flexible printed RFID antennas, with particular attention to antenna design, material selection, fabrication technologies, and applications. The challenges in each aspect are also explored. Further research should concentrate on the development of innovative materials with improved electrical properties and good surface functionality, the optimization of the fabrication processes, and the intelligent structural design of RFID antennas for multifunction operation. This paper is expected to provide guidance and new ideas for the development of flexible RFID tag antennas.