New nanogenerator may lead to human-powered smartphones

A device known as a biocompatible ferroelectret nanogenerator, or FENG, could one day be used to generate power all sorts of portable and wearable devices using human motion.

Michigan State University
Michigan State University scientists have created a new way to harvest energy from human motion, using a thin, non-toxic device that can be folded to create more power.

Touchscreens have become a ubiquitous feature of modern life for people around the world. Millions of smartphones have been poked, prodded, and swiped, running down batteries constantly.

But researchers at Michigan State University have created a new kind of electric generator that could one day store the energy from touching and swiping a smartphone that may one day be used to help charge smartphones using nothing but day-to-day human motion.

The device is known as a biocompatible ferroelectret nanogenerator, or FENG. Using relatively low-cost and environmentally-friendly materials, FENG converts the energy from touching or pressing it into electricity. While similar devices powered by motion already exist, this one is thin, foldable, and relatively cheap to produce, creating a means of generating electricity that could use the energy from touch to power smartphone screens in the near future.

The researchers created the device by layering thin sheets of materials like silver, polyimide, and polypropylene ferroelectret into a paper-thin film. Each layer contains ions, atoms or molecules that carry an electric charge. The folded film generates electricity when compressed, with each fold increasing the potential of the device for generating even more usable electric energy from the same amount of mechanical force.

"Each time you fold it you are increasing exponentially the amount of voltage you are creating," Nelson Sepulveda, associate professor of electrical and computer engineering and lead investigator of the project, said in a statement. "You can start with a large device, but when you fold it once, and again, and again, it's now much smaller and has more energy. Now it may be small enough to put in a specially made heel of your shoe so it creates power each time your heel strikes the ground."

According to a study detailing the production of the FENG, published in the journal Nano Energy, the device was able to provide power to a bank of 20 green and blue LEDs, as well as a small LCD display exclusively powered by the user's touch. 

"What I foresee, relatively soon, is the capability of not having to charge your cell phone for an entire week, for example, because that energy will be produced by your movement," said Dr. Sepulveda in the statement.

Since the device is small and lightweight, it could potentially be used in a number of small electronic devices. Compression from human movement could one day provide a greener alternative to conventional charging methods. But the FENG has a long way to go before commercial development, and the research team wants to fine-tune the science of the device before making any kind of deal for public consumption.

"At this point we're still trying to understand all the details on how the device operates and works so that we could optimize the power that we could extract from the device and make it more efficient," Sepulveda told Michigan Radio.

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