Smart textile sleeve integrates display, touch and sensors

Researchers from the National University of Singapore have developed a fibre that functions as pixels and senses touch at the time same, integrating 54 fibres into a sleeve to serve as a touchscreen built into a garment.

The sleeve displays images and video, responds to finger presses and connects wirelessly to other devices, while staying washable, breathable and flexible like ordinary clothing. The development enables the creation of garments that act as a direct interface to a wearer’s health data and their digital devices, with no rigid screen involved.

“What made this possible was our ability to construct the graphical user interface (GUI) system from electronic building blocks in fibre form — similar to traditional yarn, but with the sophisticated electronic functionality built directly into the fibres,” said Assistant Professor Tural Khudiyev.

The team, led by Khudiyev, have published their findings in the journal Nature.

Image caption: Using a novel interconnection architecture and thermal fibre drawing process that integrates thousands of microelectronic devices along a single fibre, the NUS team created touch-sensitive and pixel layers within a thread just one millimetre thick and 10 metres long. Image credit: National University of Singapore

To build a fibre-enabled garment display, the researchers developed a programmable method that creates connection points along tiny, insulated wires exactly where each microchip needs them. A laser exposes these locations, while controlled surface wetting guides molten solder to bond only at the programmed points. This enabled the team to integrate more than 5000 chips through over 20,000 electrical connections.

The strip of interconnected digital LEDs was then integrated into a multilayer fibre using a thermal drawing approach, thereby enabling the precise formation of the touch-sensitive and pixel layers within a thread just a millimetre thick and 10 metres long. A layer beneath the LEDs senses touch — pressing the fibre completes a circuit and the signal reveals exactly where your finger landed so the nearest pixel lights up.

“A fibre has a one-dimensional, axially symmetric geometry, which makes it difficult to build complex circuitry using approaches developed for conventional two-dimensional electronics. We overcame this limitation through a new interconnection architecture, which enables thousands of microelectronic devices to be integrated and interconnected along a fibre,” Khudiyev said.

Image caption: A layer beneath the LEDs senses touch, lighting up the nearest pixel when the fibre is pressed. Image credit: National University of Singapore

The prototype features 54 pixel fibres, each carrying 96 LEDs, threaded into the forearm of a sleeve to form a 96 x 54-pixel display measuring 168 x 105 mm, refreshing 30 frames per second with 8-bit colour depth. Each fibre has its own control channel, so a fault in one line leaves its neighbours working normally. The system can also register several touches at once.

Alongside the pixel fibres, the team integrated peripheral fibres made the same way, carrying a microphone, a speaker and sensors that track movement, find magnetic north, measure temperature and gauge how bright the surroundings are.

Together, the fibres support the functions early generations of smartphones could perform: run a calculator, show a photo gallery, play a video at 30 frames per second (25 frames per second with synchronised audio), work as a compass, respond to voice commands, and receive images over Bluetooth. They can even rotate the screen and adjust brightness automatically. When positioned under the arm, the temperature-sensing fibre lets the sleeve read and display body temperature.

Importantly, the garment still behaves like fabric. Light output and touch response were nearly unchanged after 50 detergent washes in a typical washing machine, and after 1000 bends around a 5 mm radius. In addition, the built display is as breathable as cotton, polyester and denim, and stays within established safety limits for skin contact.

Smaller microchips and thinner fibres, both compatible with the team’s method, offer a route to sharper and larger displays. Furthermore, as the display and sensing elements sit along the length of the fibre, the thinner fibres can be knitted, weaved and embroidered using standard industrial machines. The same technology could one day perform other functions such as tracking health signs and delivering touch-based feedback.

The research team’s next step is to push the textile touchscreen further, towards higher resolution, integrated sensing and on-device AI — bringing display, touch, sensing and intelligence together within the same textile platform.

Top image caption: The fibres support the functions early generations of smartphones could perform. The 96 by 54-pixel display can run a calculator, show a photo gallery, play a video, work as a compass, respond to voice commands, receive images over Bluetooth, and read and display body temperature. Image credit: National University of Singapore