The flexible RFID tag employs a high-performance semi-conductive carbon nanotube composite which could enable the roll-to-roll manufacture of UHF RFIDs using low-cost printing processes. RFID should greatly enhance work efficiency in retailing and logistics because it offers long-distance communication, batch reading, and other benefits. However, conventional silicon RFID tags have not become widespread because of the cost of silicon chips, comparatively expensive due to the complex manufacturing processes employing high temperatures and vacuum environment. Such tags also require IC chip to be mounted onto a label.
Toray has engaged in R&D on RFIDs with printed materials, focusing on high-performance carbon nanotube composites. The semiconductor used for these UHF RFIDs delivers a mobility of 182 cm 2/Vs, which Toray says is a new world record. While thin film transistors (TFTs) are either p-type (positively charged) or n-type (negatively charged), carbon nanotubes are normally p-type. Toray employed proprietary material technology to develop an n-type feature, realizing both p- and n-type TFTs that would be necessary to form power-saving, low-cost ICs. The RFID prototype incorporates a 24-bit memory entirely printed using the new proprietary material and process technologies. It was able to communicate wirelessly with UHF waves (860–960 MHz) across 20-cm distance.
Next, the company wants to design a 60-bit memory and improve communication performance, including communication distance, while developing on-film manufacturing technologies to commercialize the printed RFIDs. Toray’s research was supported in part by the “Low Carbon Technology Research and Development Program” of Japan’s Ministry of the Environment.