Future smart clothes could pack serious gadgetry

In the future, leaving your phone charger at home will mean only one thing: You forgot to put on pants.

Just as smartphones untethered users from their desktop computers, smart clothing is poised to bring personal electronics out of our pockets and onto our sleeves.

The current generation of wearable technology that includes smart glasses and watches is still more marginal than mainstream. Google Glass fizzled out, and nearly a third of the people who buy fitness trackers lose interest over time. But gadget-packed garments may have an edge when it comes to seamless integration into our lives.

“One conference, somebody stood up and [said], ‘I get that wearable technology is a thing, but I just don’t think I’m going to be willing to get up every single day and remember to put something on,’ ” recalls wearable technology researcher Lucy Dunne. “I looked at her and said, ‘You’re wearing clothes right now. I’m pretty sure you do that already.’ ”

Plus, technology-laden clothing is “right next to and against your body. It has a large surface area compared to personal devices, and it goes with us everywhere,” says Dunne, of the University of Minnesota campus in St. Paul. “That kind of access is … rich with opportunity.”

Some advanced apparel is already for sale, like gloves threaded with heat-conducting wires to warm fingers on extra cold days, or bathing suits equipped with UV sensors to alert suntanners when they are close to overbaked. But engineers have set their sights on a vast menu of souped-up clothes that could make daily life more convenient — or just better looking.

Job one, though, is to refashion conventional electronics. Typical battery packs and digital displays are too rigid and heavy for weaving into everyday duds. Engineers are getting creative to make lightweight, flexible devices that keep clothing comfortable and still perform as well as their clunky counterparts. Once researchers have built something that works well and is reasonably wearable, they still have to make sure their stuff is sturdy enough to withstand daily wear and tear, not to mention runs through the laundry.

Most next-gen clothing is years away from hitting retail racks. In fact, a lot of the tech hasn’t left the lab yet. But fashionistas and gearheads can look forward to a future where electronic clothes are in vogue. Here’s a sneak peek.

1. Change your fashion on the fly

Clothing woven from color-changing yarns could give a whole new meaning to the phrase “goes with anything.”

Most existing color-changing textiles, like sun-activated T-shirts with designs that go from white to rainbow, are triggered by shifts in ambient lighting or body heat. Now, researchers have created clothes that change color with the tap of a smartphone screen.

These garments, presented April 4 in Phoenix at the Materials Research Society spring meeting, are made from yarns as thick as a few strands of human hair. Each yarn comprises a copper wire sheathed in a polymer sleeve. The polymer could be polyester, nylon or some other material, depending on how soft or sturdy you want your fabric, says optics and photonics researcher Joshua Kaufman, a codeveloper of the yarns at the University of Central Florida in Orlando.

The polymer sleeves are laced with pigments that shift color in response to temperature changes too subtle for the wearer to feel. The wearer controls the clothing’s appearance by sending Wi-Fi signals from a smartphone to a battery attached to the garment. The battery feeds electric current into the yarn’s copper wire, heating the pigment to activate a color switch. These yarns could make clothes that rotate between solids, stripes, plaids and other patterns.

Fashion trendsetters and people who just can’t decide what to wear in the morning probably stand the most to gain from this technology.

But it could have benefits for the rest of us, too. Spilled food on your light-colored shirt at lunch? Hide the stain with a darker hue. Want to wear a lighter shade when you’re out in the sun or biking home in the dark? Tap an app. Need to sneak in a second-day wear after skipping laundry day? No problem.

This kind of fabric could also be used for bags, car upholstery, curtains and furniture, says optics and photonics researcher Ayman Abouraddy, also at Central Florida. “We don’t anticipate more than a year or two before you could buy something [made of these fabrics] from the mall,” he says. 

2. Never forget your ID or keys

Someday, you may be able to embellish your clothes with enough data to get you in the building.

Researchers have created passcode-storing clothes made with thread that contains silver or copper filings. Normally, the magnetic poles of atoms in those metallic threads are pointed in random directions. But holding a magnet close to the thread aligns all the poles in a single section of cloth to point either north or south. Those magnetic orientations encode a bit of data, a 1 or 0, which an instrument called a magnetometer can read.

This data-embedded fabric, presented last October in Quebec City at the Association for Computing Machinery’s Symposium on User Interface Software and Technology, holds onto its magnetic information through washing, drying and ironing — at least for the short term. The strength of the data signal wanes by about 30 percent over the course of a week.

The material can be remagnetized with the same or a different pattern of 1s and 0s, but the researchers first have to build a device that can rewrite this data, similar to the tech used to reprogram hotel keycards, says Justin Chan, a computer scientist and engineer at the University of Washington in Seattle.

Chan and Washington colleague Shyam Gollakota have written magnetic codes into neckties, belts and wristbands, but the tech is still in the nascent stage. Right now, each 1 or 0 is about 2 centimeters across. The researchers are working on packing more data into smaller swatches, Chan says.

Once data-storing clothing is available, you could simply scan your sleeve to enter your office or apartment building. To some people, that may not seem like much of an advance. But the forgetful types who misplace their keys every other day might appreciate one less thing to scramble for on the way out the door.

3. Micromanage your moves

Training yourself to drive a golf ball, play piano or just sit with better posture could get a whole lot easier, thanks to motion-sensing clothes that detect the slightest twitch.

“If you want to know exactly what somebody’s doing — whether or not they’re bending their knee in a healthy way, or what their heart rate and muscle activity is telling you about their emotional state — then you need sensors everywhere,” Dunne says.

To that end, industrial engineer Joshua DeGraff and colleagues have built superthin motion detectors that can be embedded in anything from shoulder braces to shoe soles.

The key component of these sensors is a sheet of material called buckypaper — a dense mesh of carbon nanotubes about as thick as a red blood cell is wide. Normally, buckypaper conducts electricity with no problem (SN: 3/8/14, p. 18). But stretching the material creates gaps in the nanotube network that stymie the flow of electric charge. DeGraff’s team at Florida State University in Tallahassee is using that weakness as an advantage. Connecting a piece of buckypaper to a circuit and measuring changes in electrical resistance across the paper can reveal how much the bucky-paper has been stretched. 

Sensors fashioned by DeGraff’s team register as little as a 0.005 percent change in material length. The sensors, described last November in Materials and Design, could be powered by watch-sized batteries, DeGraff says.

Buckypaper sensors could prove useful for people who need to micromanage their movements in the short term — like physical therapy patients whose rehab requires them to move in exactly the way their therapist prescribed.

4. Add light to your life

Light-up clothes of the future will look and feel less like your uncle’s ugly Christmas sweater and more like the sleek suits in the movie Tron: Legacy.

Actress Claire Danes lit up the 2016 Met Gala in a gown laced with LEDs. But standard, semiconductor-based LEDs are too stiff and brittle to make comfortable daywear, says Seonil Kwon, an engineer at the Korea Advanced Institute of Science and Technology in Daejeon, South Korea. Organic LEDs, or OLEDs, on the other hand, are razor-thin and superpliable. 

An OLED display contains a layer cake of organic, or carbon-based, material films. The OLED lights up when a power source — like a battery — drives electric charge from one layer of organic material to another, where negative electrons pop into positive holes in the material. Whenever a positive hole and negative electron pair off, they release a brief flash of light. Many positive-negative meetups per second keep the OLED lit.

OLEDs are typically built on panes of plastic or glass, but Kwon and colleagues have created OLEDs on fabric. The researchers lay these OLEDs, just 200 nanometers thick, atop a polyester film that’s laminated onto fabric made of tightly woven, superfine polyester fibers. The setup is more flexible than the plastic platforms used to make bendy displays.

The new fabric-based OLEDs are bright enough to rival current display technology, Kwon and colleagues reported last July in Scientific Reports. Each OLED emits only a single color, but engineers could make fabric-based screens with many color-changing OLED pixels to display messages. Kwon’s group made OLED threads too, for lettering and patterns, reporting the work in the Jan. 10 Nano Letters.

Are there consumers who find the act of pulling a phone from their pocket so burdensome that they want to tote a smartphone screen on their sleeve? Who knows. But clothes sporting single-color OLEDs could light up pedestrians and bikers at night. Kwon also imagines creating OLED garments that glow white to provide light therapy. Some people who suffer from seasonal affective disorder find relief by sitting near a special lamp called a light therapy box, which gives off white light to mimic outdoor sunlight (SN: 4/23/05, p. 261). A shirt or underside of a hat brim that glows white could offer light therapy that goes where you go.

5. Power up with sun and your moves

After a full day’s work, “no one wants to have to take off their shirt and plug it in,” says Rajan Kumar, a nanoengineer at the University of California, San Diego. Long battery life in smart clothing is key. So why not design wearables that continuously convert sunshine and motion energy into electricity?

Researchers debuted this kind of energy-harvesting fabric in 2016 in Nature Energy. Primarily made of synthetic polymers and wool fibers, the fabric is lightweight, flexible and breathable. A 4-by-5-centimeter piece worn for a run in the sun can charge up a cell phone, says Stanford University materials scientist and engineer Jun Chen, who did the work in the lab of Zhong Lin Wang at Georgia Tech.

The sunlight-catching patches of fabric are threaded with photovoltaic wires. When sunshine strikes a wire, light particles knock electrons out of atoms in one layer of material, leaving behind positively charged holes. Another electron-conducting layer of the wire collects those loose electrons, while a third layer gathers up the positively charged holes. That charge separation creates a voltage to produce electricity that can power devices.

Meanwhile, other patches of this fabric transform the energy of motion into electricity. These swatches contain strips of a polymer called PTFE — which hoards electrons — interlaced with copper wires — which easily give up electrons. Whenever the fabric is folded or compressed, some of the copper wires’ electrons rub off on the PTFE strips.

This process builds up static charge, just like combing your hair or peeling off a sweater in the winter. When the fabric relaxes, the negatively charged PTFE strips separate from the positive copper wires, creating voltage to power devices. Strips of this material could be sewn into sleeves to generate energy from the swing of your arms, or into the soles of shoes to get energy from footsteps, says Georgia Tech’s Wang, a materials scientist and engineer.

The energy this fabric gathers up when you’re moving around or sitting in the sun could also be stored in a capacitor or battery attached to the garment (SN: 11/26/16, p. 5). The storage device might be made of ink containing zinc-silver oxide printed directly onto clothing, as described in 2017 in Advanced Energy Materials. Or perhaps the energy could be stored in zinc-ion yarn batteries, like ones reported in the April 24 ACS Nano.

This energy-harvesting material could also be built into tents that, when bathed in sun or rustled by wind, could charge campers’ devices.

6. You as a walking generator

If clothing were packed with thermoelectric generators, body heat could be turned into electricity.

Researchers at North Carolina State University in Raleigh work with a button-sized generator containing a grid of semiconductor rods sandwiched between two ceramic plates. When one side of the generator is hotter than the other — say, when that side is close to your skin while the other is exposed to air — electrons at the warm end of each semiconductor rod get jittery. These electrons diffuse toward the cold side of the device, creating a tiny voltage across the rod. Connecting the positive end of each rod to the negative end of the next adds up these voltages like stacking batteries in a flashlight.

Daryoosh Vashaee, an electrical engineer at NC State, and colleagues embedded these thermoelectric generators in a T-shirt. If someone wearing the shirt is just sitting around, the generator doesn’t produce much power because the temperature difference between skin and the surrounding air is so small. But if that person gets up and walks or jogs, a boost in body temperature will heat the side of the generator inside the T-shirt, while wind cools the exposed side of the generator. In one test, the generators pumped out six microwatts of power per square centimeter when the wearer was walking and 18 μW/cm² during jogging, the researchers reported in 2016 in Applied Energy.

Unfortunately, that’s nowhere near enough to power a smartwatch or a phone. But generators a couple centimeters across could feed low-power sensors like heart monitors. And researchers are trying to boost the generators’ efficiency to support more power-hungry electronics. If researchers can make thermoelectric generators better powerhouses even when a wearer is seated, this tech would have one advantage over sunshine-motion harvesting clothing: You could power up your stuff while vegging out on the couch.