"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," he added.
The system is based on the group's research on stretchable battery technology. Pint's team reconstructed the battery with both positive and negative electrodes made from the same material. Although this prevents the device from storing energy, it allows it to fully exploit the voltage changes caused by bending and twisting and so produce significant amounts of electrical current in response to movement, generating 40 microwatts per square foot over the full duration of movements as slow as 0.01 Hz.
One of the challenges is that the voltage generated is low, in the millivolt range, but the team is looking at low voltage LCD screens. "We are already measuring performance within the ballpark for the power requirement for a medium-sized low-power LCD display when scaling the performance to thickness and areas of the clothes we wear." said Pint.
There are other unexpected applications. "When incorporated into clothing, our device can translate human motion into an electrical signal with high sensitivity that could provide a historical record of our movements. Or clothes that track our motions in three dimensions could be integrated with virtual reality technology. There are many directions that this could go," said Pint.
For more, see "Ultralow Frequency Electrochemical-Mechanical Strain Energy Harvester Using 2D Black Phosphorus Nanosheets."
Vanderbilt University Nanomaterials and Energy Devices Laboratory
Formerly 'useless' material holds promise for flexible, smaller electronics
Flexible nanogenerator harvests energy from human motion
Flexible power generators promise self-powered wearables
New energy harvesting method harnesses power from walking, other small motions
July 28, 2017 // By Nick Flaherty