Researchers have developed a wearable device able to generate energy with a swing of the arm.
The prototype device, created by Pennsylvania State University and the University of Utah, harvests energy while the wearer is either walking or jogging.
The device is about the size of a wristwatch and can produce enough power to run a personal health monitoring system, while lowering the amount of disposable batteries needing to be used and thrown away.
The watch is made from a crystal material able to produce an electric current when compressed or change shape.
This was coated on both sides of a flexible metal foil to a thickness up to five times greater than previously attempted – a greater volume of the active material meant more power could be generated.
In the future, the team believes they can double the power output created.