There is a lot of energy from wind, waves and body movement around, but it is not often used. The authors of the new work have created a device that can convert this type of mechanical movement into electricity and can handle it even under water.
The new development is made of a liquid metal alloy of gallium and indium, which is immersed in a hydrogel – it is a soft, elastic polymer with a lot of water. The water in the hydrogel contains dissolved salts – ions – they collect on the surface of the metal and can induce a charge in it.
If the area of the metal increases, then this creates a greater density for the attraction of the charge. This generates electricity, which traps the wire attached to the device.
Since the device is soft, any mechanical movement can lead to its deformation. Therefore, it is versatile for harvesting mechanical energy. For example, a hydrogel is flexible enough to stretch to five times its original length.
Michael Dickey, article author
Through experiments, the researchers found that deformation of the device by just a few millimeters creates a power density of about 0.5 MW. This amount is comparable to other popular energy harvesting methods, but they cannot work in humid environments.
The authors of the new work are going to use their device in order to power wearable devices. Another project is to harvest the energy of ocean waves.