Will this T-shirt ever power your cell phone? UCSD researchers think so

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Call it the Electric T-Shirt. Or, as researchers at the University of California, San Diego have dubbed it, the “portable microgrid.”

Whatever its nickname, the long-sleeved shirt designed by the masterminds of the Jacobs School of Engineering can harvest and store energy while the wearer moves or exercises. The school’s nanoengineers predict that one day the prototype will be refined to the point that electronic devices like cell phones no longer have to rely on the power grid for power, but can work with the clothes people all wear. days.

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And, perhaps, generate energy that is literally at our fingertips.

“What we want to achieve in the end is to have a system where you don’t have to think about charging anymore,” said Lu Yin, a PhD in nanoengineering. student who worked closely with Joseph Wang, director of the Center for Wearable Sensors at UC San Diego.

The shirt collects or harvests energy from the human body which can be stored and then used to power small electronic devices, such as an LCD wristwatch.

Biofuel cells powered by the sweat produced by the wearer are located inside the shirt at chest level. On the shirt’s forearms and torso, triboelectric generators harvest energy when the user walks or jogs. At the same time, supercapacitors placed on the jersey’s chest temporarily store energy and then discharge it to power devices.

It looks like the prototype would be bulky and hard to wear, but it’s lightweight, flexible, and unaffected by bending, bending, or wrinkling. The shirt can be washed in water, as long as no detergent is used.

Close-up of the “portable microgrid”, a washable shirt that harvests and stores energy from the human body. The supercapacitors on his chest can discharge energy to power small electronic devices.

(University of California San Diego)

The energy generated by the swinging of the user’s arms when running or walking works on the same principle as static electricity.

“It’s very energy-efficient and very suitable for those low-power, low-power applications,” Yin said, adding that the design of the shirt is unique in terms of functionality.

The idea for the shirt was inspired by microgrids which have the ability to operate independently from the power grid.

Wearable and wearable electronic devices, such as smart watches, have grown in popularity. Combined with the near-universal adoption of personal computers, iPhones, and other devices, there’s a concerted effort to find alternative power sources to power them all.

Self-powered technology envisions devices that can operate on their own, without relying on an external power source. Such a transition would reduce the need for the countless number of batteries that currently power our gadgets, not to mention the impact such an adaptation would have on potentially reducing energy demand on an increasingly strained electrical system.

“I think the (research and development) is mostly about how to perfect the energy harvesting part,” Yin said. “What we have demonstrated is energy harvesting down to a few hundred microwatts. We want that to be increased, maybe tenfold, and we are getting there.

The key will be to develop the technology. The UC San Diego shirt isn’t yet powerful enough to run, say, a cell phone.

But Yin sees the shirt as a way to provide “intelligent sensing” to monitor things like the wearer’s heart rate and oxygen levels. “We are also working on wearable blood pressure monitoring,” he said.

Private companies in the sportswear industry have expressed interest in UC San Diego’s research. Yin sees another practical application for the shirt: generating luminescence for joggers running at night.

“We are very optimistic about the whole trend in wearable electronics, especially the integration of these energy storage devices with energy harvesters,” Yin said. “We see a roadmap for future development.”

In related research, engineers at UC San Diego have developed a thin, flexible band that can be wrapped around fingertips like a bandage. The wearable device can generate small amounts of electricity when a person’s finger sweats or when the finger is squeezed.

Billed as the first of its kind, the device measures around 1 centimeter square, or less than half an inch. A carbon foam electrode padding absorbs sweat and converts it into electrical energy.

Fingertip Device at UC San Diego

Researchers at UC San Diego have designed a fingertip device that absorbs sweat and converts it into electrical energy.

(University of California San Diego)

You wouldn’t think your finger sweats a lot, but “what we figured out is that on the fingertip, the sweat rate is much higher compared to other parts of the body,” Yin said. “That’s why we have so many grooves on the finger because it has hundreds of sweat glands along each groove.”

Electrodes equipped with enzymes trigger chemical reactions between lactate and oxygen molecules in sweat to generate electricity. When the wearer sweats on the band, electrical energy is stored in a small capacitor and can be discharged to devices when needed.

“The level of energy we generate is at best, maybe hundreds of microwatts per finger,” Yin said. “That’s still a long way from powering a cellphone.”

The UC San Diego researchers had a subject wear the device on a finger while performing sedentary activities. After 10 hours of sleep, the device collected nearly 400 millijoules of energy, enough to power an electronic wristwatch for 24 hours. An hour of typing and clicking a mouse allowed the device to collect nearly 30 millijoules.

Although the fingertip device and the “electric T-shirt” represent two different studies, the nanoengineers at UC San Diego see their research on the garments as an integrated effort.

“We’re definitely heading into the next generation of electronics,” Yin said. “We envision it being more flexible, more conforming to the human body, more durable and ultimately self-sufficient. That’s the ultimate goal we want to achieve.

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