Previously, researchers have used TENG Technology (triboelectric nanogenerators) small devices that covert mechanical energy into electricity to make energy harvesting backpacks, but those bags had relatively low power outputs to provide actual benefits such as load lightening and shock absorption. Zhong Lin Wang, Jia Cheng and colleagues wanted to design a prototype that overcame these limitations.

The researchers incorporated into the backpack two elastomers to save labor and absorb shock that stretched and shrank, it also retains the bag steady as the wearer walked. Researchers also claim it result in about a 20% reduced force on the wearer. Meanwhile, movement between the frame of the backpack and its load during walking drove a TENG to convert mechanical energy into electricity, with 14% efficiency. The researchers showed that the bag could power LEDs, an electric watch and fluorescent tubes. 

The researchers foresee the backpack has promising potential as a power source for small-scale wearable and portable electronics, GPSs and health care sensors once few challenges are addressed, such as improving the energy conversion efficiency are overcome.

The study has been published in ACS Nano.

Project receive funding from the National Natural Science Foundation of China, the National Science and Technology Major Project of China, the National Key Research and Development Program of China and the Tsinghua University Initiative Scientific Research Program.