Researchers turn clothes into electronic displays

Researchers have demonstrated the world’s first stretchable and conformable thin-film transistor driven LED display laminated into textiles, an advance that paves the way to wearable displays in clothing providing users with feedback.

The breakthrough has been made by researchers from the Holland’s Holst Centre, Belgium headquartered imec, and CMST, imec’s associated lab at Ghent University.

Wearable devices such as healthcare monitors and activity trackers are quite common, but to date they haven’t been integrated into clothing. Doing so will make wearable devices less obtrusive and more comfortable, encouraging people to use them more regularly and increase the quality of data collected. A key step towards realising wearable devices in clothing is creating displays that can be integrated into textiles to allow interaction with the wearer.

“Wearable devices allow people to monitor their fitness and health so they can live full and active lives for longer. But to maximise the benefits wearables can offer, they need to be able to provide feedback on what users are doing as well as measuring it. By combining imec’s patented stretch technology with our expertise in active-matrix backplanes and integrating electronics into fabrics, we’ve taken a giant step towards that possibility,” said Edsger Smits, senior research scientist at Holst Centre.

The display is said to be very thin and mechanically stretchable. A fine-grain version of meander interconnect technology was developed by the CMST lab at Ghent University and Holst Centre to link standard (rigid) LEDs into a flexible and stretchable display.

The LED displays are fabricated on a polyimide substrate and encapsulated in rubber, allowing the displays to be laminated in to textiles that can be washed. Furthermore, the technology uses fabrication steps that are known to the manufacturing industry.

Following an initial demonstration at the Society for Information Display’s Display Week in San Jose, USA earlier this year, Holst Centre presented the next generation of the display at the International Meeting on Information Display (IMID) in Daegu, Korea where smaller LEDs are now mounted on an amorphous indium-gallium-zinc oxide (a-IGZO) TFT backplane that employs a two-transistor and one capacitor (2T-1C) pixel engine to drive the LEDs. These second-generation displays are claimed to offer higher pitch and increased, average brightness. The presentation featured a 32x32 pixel demonstrator with a resolution of 13 pixels per inch (ppi) and average brightness above 200 candelas per square meter (cd/m2).