Carbon Nanotube-enabled "Power Felt" Could Eventually Power Your Cell Phone

An inexpensive and efficient thermoelectric material promises to recharge your cell phone and other devices with body heat

2 min read
Carbon Nanotube-enabled "Power Felt" Could Eventually Power Your Cell Phone

Researchers at the Wake Forest University Center for Nanotechnology and Molecular Materials have developed an inexpensive thermoelectric material that could be a solution for powering small electronic devices, like cell phones.The new material can convert differences in temperature into electrical energy more efficiently and inexpensively than existing solutions.

As reported in the journal Nano Letters, the material is a thin film made from a combination of multi-walled carbon nanotubes and polyvinylidene fluoride. While carbon nanotube/polymer composites are known to exhibit thermoelectric effects, the researchers discovered that they could generate more voltage by layering the film: the thermoelectric voltage generated was the sum of contributions from each layer, which considerably boosted the thermoelectric conversion efficiency.

The resulting material resembles humble felt in appearance and texture, which led the researchers to call it “Power Felt.”

Until now, thermoelectrics have been a tantalizing technology for powering all sorts of devices, but has remained largely untapped in commercial markets because of a lack of suitable materials. Existing materials either displayed poor thermoelectric conversion efficiency or were prohibitively expensive for commercial use. For instance, bismuth telluride, one of the materials most often used in commercial thermoelectric products like mobile refrigerators and CPU coolers, can cost as much as $1000 per kilogram.  In contrast, the Wake Forest researchers expect that Power Felt would only cost $1 to add to a cell phone cover.

“Imagine it in an emergency kit, wrapped around a flashlight, powering a weather radio, charging a prepaid cell phone,” says David Carroll, director of the Center for Nanotechnology and Molecular Materials and head of the team leading this research. “Literally, just by sitting on your phone, Power Felt could provide relief during power outages or accidents.”

It seems there still is some question as to whether the Power Felt can actually generate enough current to power some of the items they’ve put on their list of potential applications. At present, seventy-two stacked layers of the carbon nanotube/polymer thin film can produce 140 nanowatts of power. So the researchers are looking into ways of adding more layers to the material to generate more.

Perhaps the answer is not just in boosting the power output of the thermoelectric material, but reducing the power consumption of the devices.

Last year I reported on work at the University of Illinois’s Beckman Institute for Advanced Science and Technology in developing a system that uses carbon nanotubes to control bits and lower power switching in phase change materials. At the time, one of the expected results of that work was that cell phones could be manufactured so that they consumed so little energy they could be powered by merely harvesting the thermal or mechanical energy from the environment.

Power felt may provide just such a cost-effective method for harvesting that thermal energy.

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Two Startups Are Bringing Fiber to the Processor

Avicena’s blue microLEDs are the dark horse in a race with Ayar Labs’ laser-based system

5 min read
Diffuse blue light shines from a patterned surface through a ring. A blue cable leads away from it.

Avicena’s microLED chiplets could one day link all the CPUs in a computer cluster together.

Avicena

If a CPU in Seoul sends a byte of data to a processor in Prague, the information covers most of the distance as light, zipping along with no resistance. But put both those processors on the same motherboard, and they’ll need to communicate over energy-sapping copper, which slow the communication speeds possible within computers. Two Silicon Valley startups, Avicena and Ayar Labs, are doing something about that longstanding limit. If they succeed in their attempts to finally bring optical fiber all the way to the processor, it might not just accelerate computing—it might also remake it.

Both companies are developing fiber-connected chiplets, small chips meant to share a high-bandwidth connection with CPUs and other data-hungry silicon in a shared package. They are each ramping up production in 2023, though it may be a couple of years before we see a computer on the market with either product.

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