A flexible device captures energy from human movement

A flexible device captures energy from human movement

The system is low cost, as thin as a sheet of paper and can be adapted to many applications and sizes

   Engineers from Michigan State University have created a new way to collect energy from human movement, with a device similar to a film that can be bent to create more energy.

With a low-cost device, known as a nanogenerator, the scientists successfully operated an LCD touch screen, a bank of 20 LED lights and a flexible keyboard, all with a simple touch or movement of pressure and without the help of a battery.

   Nelson Sepulveda, associate professor of electrical and computer engineering and principal investigator of the project, said that these innovative findings, published in the magazine 'Nano Energy', suggest that "we are on the road to portable devices driven by the human movement."

"What I foresee, relatively soon, is the ability to not have to charge the mobile phone for a whole week, for example, because that energy will be produced by its movement," said Sepulveda, whose research is funded by the National Science Foundation.

The innovative process begins with a silicone wafer, which is then manufactured with several layers, or thin sheets, of environmentally friendly substances that include silver, polyimide and polypropylene ferroelectret. Ions are added so that each layer of the device contains charged particles. Electrical energy is created when the device is compressed by human movement, or mechanical energy.

Like a sheet of paper

The completed device is called a biocompatible ferroelectret nanogenerator, or FENG. The device is as thin as a sheet of paper and can be adapted to many applications and sizes. The device used to turn on the LED lights was the size of the palm of one hand, for example, while the device used to power the touch screen was as small as a finger.

Advantages such as lightweight, flexible, biocompatible, scalable, low cost and robust could make FENG "a promising and alternative method in the field of mechanical energy harvesting" for many autonomous electronic devices such as wireless headsets, cell phones and other devices with touch screen, says the study.

Surprisingly, the device also becomes more powerful when it is bent. "Every time you bend it's exponentially increasing the amount of tension you're creating," Sepulveda said. "You can start with a large device, but when you fold it once, and again, and again, it is now much smaller and has more energy, now it can be small enough to be placed on a special shoe heel and create energy every time the heel hits the ground when walking. "

Sepúlveda and his team are developing a technology that would transmit the energy generated from the heel, for example, to a wireless headset.