Flexible use

Abstract

With the growth of the Internet Of Things, significant resources are being put into the development of smart garments. Ideally, the systems in these garments should be fully flexible to allow greater comfort and a wider range of applications. Now, a team jointly from Loughborough University (UK) and the National Centre of Scientific Research “Demokritos” (Greece) have developed an all-textile flexible method of connecting textile transmission lines. The method is designed to allow easy connection, although currently requires clamps to keep the connection stable In wearable communication systems currently in operation, rigid connectors such as coaxial SMA connectors are used to connect antennas to the electronic systems required to operate them. These rigid parts can make wearable technology uncomfortable and more prone to damage. With this in mind, the team previously investigated connection methods that could eliminate the need for such rigid connections. Of the methods investigated, complementary overlap (CO) emerged as the most promising. In this method two identical striplines are overlapped (as show in the images). This time, the team has investigated issues related to the structural modification of CO and to the fabrication of a connector. To optimise the connector the team had to investigate fabrication issues such as materials and structure. Felt was used as the dielectric substrate and Nora-Dell fabric as the conductive textile. Through experiments the team found, out of the three adhesives investigated (a universal adhesive, Hemming-web and sewing using non-conductive thread), that Hemming-web gave the best performance. The team also discovered that extending the ground planes on the longest side decreased the effect of structural discontinuities on the forward transmission coefficient. “A noticeable advantage is the power transmission performance improvement (+3 dB) by the structural modification of the textile stripline interconnection method. The insertion losses of our flexible interconnection are less than 1.8 dB, which means that more than 66% of the inserted power is transmitted” Mr Tsolis, the corresponding author for the team, informed us. “Remaining challenges are to find a way of making the connector stable and flexible at the same time. This means that when the interconnection happens it needs to be stable and also flexible in terms of ease in connecting and disconnecting the transmission lines.” To keep the individual stripline parts of the CO firmly connected the team had to use clamps, as a stable measurement setup was required to evaluate the power transmission via measurements. “We believe that in terms of a final wearable realisation conductive Velcro or magnets could be used instead of clamps. The use of Velcro seems like a feasible solution for wearable and flexible systems. We plan to further investigate the implementation of supporting the proposed connection by using Velcro” said Tsolis. In the short term, the team plan to use this technology to advance their own research into wearable technologies. So far they have been continuing their work into this technology through simulations and measurements as part of the larger activities of their laboratory, which focuses on the design and analysis of wearable communication systems and related technologies. The complementary overlap method was tested against a straight transmission line made from the same materials In the long term, the team believe that the new method will increase the flexibility of wearable communication systems, and lead to the production of technologies such as garments with integrated textile striplines using flexible connectors to connect to antennas as needed. Such garments could be used in hospitals, monitoring the condition of patients and automatically informing the staff of any emergencies. When asked about the future of this sort of technology, Tsolis and the team have high expectations. “We believe that there will be a rapid explosion in the wearable antennas and electronics technology. We predict that this technology is the future of smart garments and furthermore the future of our daily lives. We would like to see, and would be very happy to witness “state-of-the-art” garments that will be capable of supporting health monitors, entertainment and sports training equipment. A smart garment could be an assistant, a doctor, a trainer etc. to every human's life.”