The road to scaling electronic clothes

We may take clothes for granted, but a lot of clever engineering makes them comfortable, aesthetically pleasing and functional, from the drape of a boxy T-shirt to the way raindrops roll off a waterproof jacket. Beyond our everyday wardrobes are even more highly engineered garments, such as bullet-stopping Kevlar vests and space suits that protect astronauts from cosmic radiation and temperature extremes.

Now engineers want to take our wardrobes further and weave in glowing threads, sensors, and other electronic components. The high-tech electronic textiles under development could expand the ways we interact with technology beyond touchscreens, keyboards and buttons, and promise more accurate, yet less obtrusive ways to monitor our physiologies. 

But before such textiles become a feature of everyday life, researchers must shift from handmade prototypes to manufacturable products, with designs that genuinely meet people’s needs. And they must find ways of making ordinarily delicate electronics as robust as a pair of jeans we wear day in, day out, without compounding e-waste and textile waste into an even worse problem. In short, there’s a mountain to climb.

Making more wearable wearables

Despite promises from analysts and journalists a decade ago that smart clothes would be everywhere in a year (or even five), wearable technology remains resolutely dominated by the smartwatch. 

In fact, electronic clothing has barely had a look in, apart from a handful of haute couture, light-up garments worn by popstars such as Take That and Katy Perry during the peak of the hype cycle (a trend revived earlier this year by Beyoncé on her Cowboy Carter tour). 

However, there is at least one wearable electronic textile product that first took off with consumers in the 1990s: the heart rate monitor. For athletes (or just hardcore running nerds), the accuracy that comes from measuring heart rate via a chest strap, rather than solely a smartwatch, makes it worth investing in a separate device. 

Like the heart rate monitor, any new wearable electronic textile must capitalise on value added for potential wearers if they are to succeed. This is why health monitoring is a key focus area: sensors embedded in a close-fitting garment can sit next to the skin to pick up clear signals from the body. 

“ECG electrodes on a T-shirt capture much more information about your heart than the pulse sensors [on watches] at the moment,” says Steve Beeby, Professor in Electronic Systems and Devices at the University of Southampton. Smartwatches, as they are confined to the wrist, perform “an awful lot of really clever processing” to capture metrics such as heart rate and step count, he adds. Electronic textiles, meanwhile, can be integrated into virtually any item of clothing and worn anywhere on the body – as well as tap into the sizeable market not served by existing wearables. “A lot of people don’t wear watches, but they all wear clothes,” says Beeby.

But so far, functional electronic clothing remains “very clunky” and expensive, he adds. Professional golfers can invest in a body suit that tracks swing to give feedback about their technique, but the sensors are bulky and must be removed to wash it. Gamers can purchase the $12,999 Teslasuit, which has full-body haptics to give a sense of touch in VR and AR (and must be professionally or steam cleaned).

The colliding worlds of electronics and textiles

In the late 1990s, Beeby was a postdoc printing hybrid electronic circuits onto rigid substrates. Heavy metal fan Beeby looked at his Iron Maiden and Ozzy Osbourne band T-shirts, screen printed with gold and silver patterns, and had an idea. “I was thinking, why can’t you print the silver and gold that we’re printing as part of circuits, onto fabric?” he recalls. 

Now a Royal Academy of Engineering Chair in Emerging Technologies at the University of Southampton, Beeby is developing electronic textiles as a platform technology for wearables and other applications. 

The main challenge for the field, he explains, is that electronics and textiles are fundamentally different, which complicates design and manufacturing. For one thing, textiles are tough. Before a pair of jeans arrives in a shop, the denim might have been dyed, bleached and pummelled with pumice stones. After all that mistreatment, we can still usually wear them a hundred times and put them through at least 50 machine washes before they start to fade or thin. Electronics, on the other hand, are normally encased in a protective box, and god forbid your AirPods go in the washing machine. 

The materials are also worlds apart structurally. Textiles are “a unique class of material,” says Beeby: porous, flexible, stretchable. “It’s the actual structure of the textile, the way it’s made – woven or knitted, for example – that plays a massive part in the way it feels and behaves mechanically.” Whereas crack the box protecting an electronic device open, and its innards are probably anchored onto a rigid substrate, the printed circuit board (PCB). 

Bringing the two together means finding ways for the electronics to survive everyday wear and tear, and making them compatible with a woven or knitted structure. Engineers have developed many ways of doing this, but one of the simplest is to take a very small flexible circuit and put it inside a chunky, shoelace-like yarn, explains Beeby. 

Another approach involves a technique common in both electronics and textile manufacturing: printing. Beeby’s spinout company, Smart Fabric Inks, sells conductive silver inks, inks that encapsulate and protect electronic components from moisture, electroluminescent inks that emit light, and piezoelectric inks that respond to pressure. With these specialised inks, Beeby explains, engineers can even create supercapacitors and batteries to power circuits, and antennas to communicate with external devices.

To make sure such newly made electronic textiles are tough enough, Beeby has testing rigs in his lab designed to replicate the rigours of everyday wear in a standardised way. A bending rig twists and bends a textile over tens of thousands of cycles. Wash testing, meanwhile, subjects the material to repeated cycles in a washing machine until failure. 

That’s one key difference between the electronic textiles under development today, and the high-fashion electronic garments worn by popstars and the like. “I haven’t seen Beyoncé’s dress, but I can imagine you certainly wouldn’t put it in a washing machine,” says Beeby. 

On the other hand, simple textile circuits made in his lab have lasted for up to 50 washes before failure – also the standard requirement for run-of-the-mill, non-electronic clothes. More complex circuits might make it to 20 washes at the moment, he adds, but the aim is to reach 100. One current line of enquiry is a common failure point at the interface between rigid components and the flexible substrate. His lab is investigating ways to avoid these sharp changes in stiffness, including with tapered stiffeners that spread the stress away from soldered contact pads. 

To top it all off, there is very little overlap in skills and expertise between the two fields. Textile engineers and electronics engineers “speak different languages”, says Beeby. “You need to get the right people together to be successful.” He believes this may be one reason why commercial examples of electronic textiles have so far been limited. 

From artisanal to automated

Engineers in the field are finding ways to gain both skillsets. When interdisciplinary researcher, designer, and engineer Irmandy Wicaksono was a PhD student at MIT, he developed a fabric keyboard that could be rolled up and taken on the road. His first prototype took a month to make. Spanning a single octave, the keyboard was sewn from ‘functional yarns and fabrics’ made from silver-plated and polymerised fibres, working similarly to those made by Beeby’s spinout. He then spent two months at a textile company in Shenzhen, China, learning an industrial 3D knitting technique. The next prototype, spanning five octaves, took just 40 minutes to knit.

The faster manufacturing process also enabled Wicaksono to experiment with different types of sensor and tactility. Thanks to piezoresistive fibres, the knitted keyboard responded not only to proximity and touch, but also to stretch and pressure. Wicaksono also architected and engineered its “squishiness” and stretchiness. By stretching the keys apart while playing a chord, the pianist can bend and alter the base sound, like a built-in wah-wah pedal.

In 2023, he put his industrial knitting machine to work on a much larger scale, with a 6-metre-high knitted pavilion for US desert arts festival Burning Man – a giant, colour-changing theremin. Embedded in the 12 ‘petals’ was a network of antennas, knitted from conductive yarns, that sensed an electric field emitted by the central structure. Revellers entering and moving around the pavilion’s electric field triggered an eerie soundscape and colour-changing, moving lights.

Now director of the Soft Technologies Lab at the National University of Singapore, Wicaksono says the field has been largely “boutique research”. He says researchers and manufacturers need to work together to go beyond one-offs and prototypes and translate these emerging materials into everyday products. The manufacturing capabilities and technologies are all there, he says, but manufacturers need to be open to more “alien” materials.

Theo Hughes-Riley from Nottingham Trent University’s advanced textiles research group holds a similar view. “If you want to create something that everyone can use, you need to develop the manufacturing techniques so it can be made at scale,” they say.

The research group is trying to automate the production of tiny electronic components. In 2022, they created a textile woven with over a thousand solar cells, which generated enough energy to charge a smartwatch. Embedding the solar cells in yarns by hand is as painstaking as it sounds (and looks): each individual cell, measuring half a centimetre by 1.5 millimetres, had to be soldered on the front and back. “We have a PhD student that’s very, very good at it now,” says Hughes-Riley. 

So far, the research group has developed a semi-automated approach, meaning that it needs minimal human input, for ‘simple’ components, such as LEDs or thermal sensors. However, more complex components are still largely made by hand. Take an inertial measurement unit, a device used for tracking motion. This involves soldering 11 terminals, each about twice the width of a human hair. “I’m sure I can get a robot to do it,” says Hughes-Riley. They are indeed training one for this very purpose, “but we’re not there yet.” 

Designing for sustainability

One day, when electronic textiles are more commonplace, like any other consumer product, we’ll inevitably wear them out. What then? 

Their fate will be more complex than a garden-variety T-shirt or a power cable, as they compound e-waste and textile waste. “Textile waste is a big issue for the planet and electronic waste is just piling up,” says Associate Professor Shaila Afroj, a researcher in sustainable electronic textiles at the University of Exeter. “We can’t treat sustainability in e-textiles as an afterthought.”

Post-consumer, we should be asking whether it will biodegrade and how long that might take, Afroj says. Another important question is whether we should integrate the electronics into the textiles or choose electronics that can be separated and upcycled. 

In a collaboration with several universities, including Southampton, Afroj is developing a biodegradable, washable T-shirt that will monitor atrial fibrillation, a heart condition that causes irregular heart rhythms. These can happen at any time, so the idea is for the T-shirt to be worn all the time and continually capture data. It is designed as an alternative to the bulky devices that people with atrial fibrillation are currently sent home from hospital with, which cannot be worn continuously, so might miss irregular heart rhythms.

To make it biodegradable, Afroj swapped metal wires and sensors for organic and graphene electronics. The fabric base is Tencel, a biodegradable fabric made from wood pulp. It’s not just the materials that can be made more sustainable. Instead of screen printing, where waste ink can pollute effluent, Afroj suggests drop-on-demand inkjet printing, which dispenses small amounts of ink directly where it’s needed.

The trade-off for sustainability, however, is performance. Silver nanoparticles in silver inks are highly conductive but not very environmentally friendly. On the other hand, eco-friendly alternatives aren’t as conductive, which Afroj believes is one of the biggest challenges to getting more sustainable electronic textiles to market.

“You want it to perform really well so that it captures all your data very safely and accurately,” she says. “You cannot really compromise on that part.” Still, she is optimistic that advances in graphene and other 2D materials, together with organic electronics, may soon not only close the performance gap, but also unlock new multifunctional capabilities, such as sensing and harvesting energy from the environment, paving the way for truly sustainable smart materials. 

Beyond the niche

Sensor-laden and haptic body suits are a start for niche audiences, albeit expensive. What might come next?

Along with a wearable successor to his knitted keyboard and theremin-pavilion, Wicaksono is developing a pneumatic space suit, designed to assist with health monitoring and support the heart in pumping blood effectively in microgravity. At Nottingham Trent, Hughes-Riley and their colleagues have developed a bevy of user-focused, wearable electronic textile prototypes, including a fall-detecting sock for older adults. To ensure the needs of those who will ultimately use the devices are met, the group has conducted workshops with potential wearers. Unsurprisingly, for the fall-detecting sock, comfort and washability were non-negotiables. 

Beeby also states that near-term applications are likely to be in specialist areas such as health monitoring, rather than general consumer uses. His lab, too, has socks in the works, in this case, wirelessly powered and designed to more accurately track physical activity. A pressure-detecting variant, meanwhile, will help prevent foot ulcers for people with diabetes. Also under way is a fully washable, motion-activated LED garment (“so we can all be like Beyoncé on the dancefloor”, he adds). 

Ultimately, electronic clothes will only become widespread if people find them genuinely useful and want to wear them. And while high costs are a barrier to adoption at the moment, there is reason to be optimistic. “Especially in healthcare and in sports, we’re seeing good progress,” says Afroj. “Once people feel the value and it’s solving an important problem – like early detection of any disease or monitoring patients – that would be a real gamechanger.”