In what could the future of touch screen technology, scientists have introduced a flexible, film-like material that generates electrical energy from human touch. This is the first step to developing smartphones and tablets powered simply by people using them. The new technology could also be used in clothing or wearables, helping us harvest the energy our body is producing all day long.
The film is what is known as a nanogenerator, producing energy by a small-scale physical change—like the tap or swipe of a finger. It works using piezoelectricity, where an electric charge accumulates in response to “applied mechanical stress.” The core structure of the film is a silicon wafer, layered with thin sheets of silver and polyimide, which work as the active material in the device. It also contains polypropylene ferroelectric and when pressure is applied to the device, the foam layer compresses, creating dipole movements. This then turns into an electric charge, capable of powering important devices we use every day.
“We’re on the path toward wearable devices powered by human motion,” electrical engineer Nelson Sepulveda told reporters. “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.”
Though the technology has not been tested on devices that require much power, it is an important step toward a new kind of piezoelectric generator. In testing, a hand-sized sheet of the material was able to generate about 50 volts. Remarkably, you can multiply the output of the charge by folding the film.
“Each time you fold it you are increasing exponentially the amount of voltage you are creating,” Sepulveda notes. Essentially, the smaller you fold the device, the more energy is produced.
Currently, researchers have no way to create a stable current from the material. Determining how to convert the voltage into a steady flow of useable current will be the next challenge. It may be a while before we see this technology implemented into our own devices but eventually it would give us a way to repurpose the energy our bodies expend.