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Go into a sporting goods store and there’s no end of performance fabrics on display: garments that promise to repel moisture or else wick it away, to insulate but breathe, to stretch, to compress, to reflect light, to devour body odor.
A new fabric being developed at Wake Forest’s Center for Nanotechnology and Molecular Materials, however, has the potential to make Gore-Tex seem about as high-tech as sackcloth. Called Power Felt, it generates electricity from heat. Wrap your cell phone in Power Felt and it could feed off your body heat to recharge while it’s in your pocket. Line the inside of a roof with it and, especially in the summer, it could power a household’s appliances. Lay it on the floor of a car and it could use the heat from the motor to run the air conditioning and radio—if it’s an electric car or hybrid, the Power Felt might even boost the mileage.
The challenge, according to David Carroll, the head of the team that created the fabric, was to make something that was electrically conductive—the way metal is—and thermally insulating—the way cloth can be. The solution Carroll’s team devised was to imprint carbon nanotubes onto a woven mat of plastic fibers. And since it takes relatively few carbon nanotubes to give the fabric thermoelectric properties, that can keep costs down. Carroll estimates that, at large scale, Power Felt could be fabricated for as little as a dollar for a swatch big enough to cover a cell phone.
“Thermoelectrics is a huge area of research,” he says, “but most people are looking at very expensive materials that produce a lot of power in a very compact form.” Power Felt is the opposite: It produces a relatively small amount of power, but because it’s so cheap, designers could use huge amounts of the very thin cloth, folding it over on itself many times to increase the current created.
Carroll is in talks with multiple investors about producing the fabric commercially, and it remains to be seen whether anyone else sees the same potential for his technofelt. But fabrics in general are one area where the sometimes hyperbolic early claims made for nanotechnology are being borne out. Engineers have been able to use things like nanopores and nanowhiskers to make fabrics that kill bacteria, clean themselves, and protect against hazardous chemicals.
Carroll believes one area of promise for Power Felt is in powering mobile sensors—electronics worn on the body, perhaps embedded in clothing, that allow doctors to track patients’ health remotely. Of course, even the consumer electronics we already carry around need plenty of energy, and it’s not easy or cheap for engineers to get more power into batteries.
When I spoke with Carroll, he was driving and on his cell phone. “While I’ve been talking to you, the back of my phone has gotten hot,” he says. “Our $1 piece of fabric would give you the same amount of boost as a $50 battery would.”