Researchers harvest electricity from a soft and stretchable device

North Carolina State University researchers created a device for harvesting energy that is soft and stretchable. Their device is designed to convert movement into electricity and can work in both wet and dry environments. The device is designed to turn the mechanical motion of the wind, waves, body movement, and vibrations from motors into electricity.

One of the most interesting aspects of their design is that the device works just as well underwater as it does on dry land. The key to the energy harvesting capabilities of the device is a liquid metal alloy composed of gallium and indium. The liquid metal alloy is encased within a soft hydrogel made using a soft elastic polymer embedded with water.

Ions in the water within the hydrogel contain dissolved salts that assemble at the metal's surface and can induce a change in the material. By increasing the surface area of the metal, there is more surface to attract an electrical charge. Electricity generated by the material is then captured by a wire that is attached to the device.

Its soft design is a key to its function allowing any mechanical motion to deform the material, making it extremely versatile for harvesting mechanical energy. The hydrogel material used in its construction is highly elastic able to be stretched to five times its normal length without breaking.

During experiments, researchers found that deformation of only a few millimeters was sufficient to generate about 0.5 mW m2. While that doesn't sound like a lot of electricity, the team says it's comparable to several other classes of energy harvesting technologies. The big benefit of the new technology compared to those existing types is that it functions in wet environments, which the other technologies cannot do. Currently, the team is working to increase the power output of their device.