Wearables

Vanderbilt U Team Develops Energy Harvester for Wearable Devices

• By Joshua Bolkan
• 07/25/17

Researchers at Vanderbilt University have developed a machine that could be placed in your clothes to harvest energy from the movement of your body and charge electronic devices.

"In the future, I expect that we will all become charging depots for our personal devices by pulling energy directly from our motions and the environment," said Cary Pint, assistant professor of mechanical engineering at Vanderbilt and director of the research, in a report on the device.

Pint said his team's device, described in a paper at ACS Energy Letters, has two advantages over those developed by others. It is "atomically thin" — the pieces are about 1/500th as thick as a human hair — and small enough to be embedded into textiles without changing their look or feel; and it can harvest energy from movements slower than 10 Hertz, all the way down to .01 Hertz, or as slow as one cycle every 100 seconds.

"Our harvester is calculated to operate at over 25 percent efficiency in an ideal device configuration, and most importantly harvest energy through the whole duration of even slow human motions, such as sitting or standing," Pint told Futurity.

The machine is a result of the team's research into how battery materials respond to bending and stretching. They have previously demonstrated that voltage rises under tension and drops under compression. Making the positive and negative electrodes from the same material allowed the team to produce significant amounts of current from human motions, though it prevented the device from storing energy as a battery.

The team then paired their findings with a "parallel breakthrough by a group at Massachusetts Institute of Technology who produced a postage-stamp-sized device out of silicon and lithium that harvested energy via the effect Pint and his team were investigating," according to Futurity, and decided to use black phosphorous nanosheets to build their device.

Aside from charging devices, the harvesters could be used to make clothes that act as LCD displays with changeable colors and patterns or to turn clothing into tools for tracking motion for applications such as virtual reality.

To read the full paper, visit pubs.acs.org. More information is available at futurity.org.