MIT extrudes electronic-laden fibres for fabric-based wearables eeNews Europe

Researchers from MIT have demonstrated how it was possible to embed and connect high speed optoelectronic semiconductor devices, including LEDs and diode photodetectors impermeably within polymer fibres as they are extruded. Detailing their technique in a Nature paper titled "Diode fibres for fabric-based optical communications", the researchers started with a polymer fibre preform whose bulk contained hundreds of micro-sized LEDs, alongside hollow channels through which they fed copper or tungsten wires as the preform was heated up and drawn into thin fibres. The mechanical deformation led the conducting wires to eventually make contact with the embedded devices, while all the electronics (contact wire and LEDs or photosensors) remained encased and protected within the fibre. With this approach, the researchers were able to connect hundreds of diodes in parallel inside a single fibre, with devices spaced less than 20 centimetres apart. As a proof-of-concept, the researchers realized two types of in-fibre devices: light-emitting and photodetecting p–i–n diodes, with built-in light collimation and focusing in the fibre cladding. A spool of fine, soft fibre made using the new process shows the embedded LEDs turning on and off to demonstrate their functionality. (Courtesy of the researchers) As the paper's title suggest, they were able to establish a 3MHz bi-directional optical communication link (think LiFi) between two fabrics woven with receiver–emitter fibres. Once woven into soft, washable fabrics, the "diode fibres" as the researchers call them were able to withstand ten machine-wash cycles, remaining fully functional and proving their worth for future smart fabrics. The fibres were woven into fabrics using a conventional industrial manufacturing-scale loom, meaning they could find commercial use within a very short time frame. In fact, the MIT researchers anticipate the first commercial products incorporating this technology will be reaching the marketplace as early as next year. The research was supported in part by the MIT Materials Research Science and Engineering Center (MRSEC) through the MRSEC Program of the National Science Foundation, by the U.S. Army Research Laboratory and the U.S. Army Research Office through the Institute for Soldier Nanotechnologies. This work was also supported by the Assistant Secretary of Defense for Research and Engineering. MIT – www.mit.edu