Leading industrial technology solutions provider, Toray Industries, has become the first in the world to communicate wirelessly across the UHF band with a printed semiconductor. To do so the company developed a high-performance semi-conductive carbon nanotube composite. Toray’s achievement has demonstrated the potential for manufacturing UHF RFIDs using low-cost printing processes to dramatically streamline retail and logistics operations. Examples include automating cash registers and efficient inventory management.
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 are not widely used because of their cost. Existing integrated circuit (IC) chips are expensive, as they are made with complex processes employing high temperatures and a vacuum environment. IC chip mounting processes are also needed. This situation drove Toray Industries to manufacture low-cost ICs and mounting process-free printed semiconductors, such as organic semiconductors.
The challenges over many years, however, have been that mobility of holes, electrons in semiconductors has been limited to 20 cm2/Vs which is a challenge for UHF RFID applications. High mobility ensures fast responses. It also enables thin film transistors (TFTs) to be shrunk, aiding miniaturization.
Toray has been engaged in R&D on RFIDs with printed materials, focusing on high-performance carbon nanotube composites. The newly developed semiconductor by the company deliver a mobility of 182 cm2/Vs — a new world record. While 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 company fabricated an RFID prototype incorporating 24-bits of memory with a low-cost printing technology by adopting this new material and proprietary device and process technologies. It was thereby able to communicate wirelessly with UHF waves across a distance of 20 cm, becoming the first in the world to do so with a printed UHF RFID tag. Toray’s product goal is to materialize an RFID tag with 60-bits of memory. By popularizing its new low-cost coated RFIDs in retailing and logistics, it will be able to promote product data collection and sharing, dramatically enhancing overall supply chain efficiency. The company endeavors to improve communication performance, including communication distance, while developing on-film manufacturing technologies, driving its aim to commercialize printed RFIDs.
Toray's research in this area was supported in part by “Low Carbon Technology Research and Development Program” of Japan’s Ministry of the Environment. It expects to combine its core polymer chemistry and nanotechnology to establish printed RFID technology and thereby contribute to streamline operations in the retailing and logistics fields, which is suffering from severe labor shortages.
