Wearable sensors are getting smarter and innovators in Japan have hit on something that may make tech in fashion even more seamless in the future.
Yoshiro Tajitsu, a professor at Japan-based Kansai University, and Teijin Limited, a technology-driven high-performance fiber manufacturer, have created wearable braided cord sensors that could integrate into everyday clothing or traditional garb, and go unnoticed.
The braided cords consist of a conductible carbon fiber yarn core, a polymer piezoelectric polyctric poly-L-lactic acid (PLLA) fiber yarn, a polyethylene terephthalate (PET) middle sheath and a conductible carbon fiber outer shield. Both parties are working to incorporate this new technology in fashion, sports apparel and interior design, to remedy issues associated with some conventional wearable sensors, including adaptability and usage.
“Our research is aimed at developing functional apparel, sometimes referred to as ‘e-textiles.’ We believe that wearable human-machine devices will enable people to interface with external devices naturally, without being limited or hindered by having to perform complicated movements, such as focusing on a display panel to rely instructions,” Tajitsu said. “Also, e-textiles must be comfortable and fashionable for wide spread acceptance. These ideas led to the development of our wearable sensors shaped like traditional Japanese braided cord or kumihimo used in kimono.”
Tajitsu’s team tapped Teijin Limited for its expertise in fiber technology and innovations. Teijin developed many advanced fibers, including Nanofront, an ultra-fine polyester nanofiber designed to deliver performance, and miraim, a high-performance membrane created to improve the fillability of fine particles. With Teijin on board, Tajitsu’s team can understand how the PLLA sensors’ fiber composition could elevate the capabilities of conventional apparel, accessories and other products.
Both parties collaborated to test various applications for the PLLA braided cords, including triggering smartphone selfies. Tajitsu’s team weaved three types of traditional Japanese decorative knots, including kame, kicchyo and awaji, to analyze the magnitude of electrical signals expected for each of them when integrated into the traditional Japanese kimono. Testing demonstrated that the largest signal would be yielded by the kame and kicchyo knots, while the awaji knot produced a smaller signal. The team concluded that they would use the kame and kicchyo knots for potential apparel applications, including triggering a smartphone to take a selfie.
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The PLLA braided cord process involves two core steps. First, it produces electrical signals in response to most 3-D motions, including twisting and bending. Coaxial cable fabrics are woven into the PLLA cords for high sensitivity and electromagnetic shielding, so the PLLA cords can work regardless of environmental noise from cellphones and other forms of electromagnetic interference. The PLLA cords could also be applicable for other products, like accessories, to help consumers monitor bodily function and pulse rates.
The sensor innovation comes on the heels of other wearable technology developments designed to elevate garments. Last month, a group of researchers from the University of Bayreuth, Donghua University and Nanjing Forestry University created fabrics that supply electricity to wearable electronic devices and perform advanced functions, including converting sunlight to heat to provide body warmth. Flexible printed electronics are also projected to elevate clothes in upcoming years, by making apparel items more comfortable, lightweight and functional for consumers.