Hikers, soldiers and schoolchildren know the weight of a heavy backpack well. Now researchers have developed a prototype that not only makes loads feel about 20 percent lighter, but also harvests energy from human movements to power small electronic devices. The new backpack, whose study is reported in DHW Nano, would be particularly useful for athletes, explorers and disaster responders working in remote areas without electricity.
Backpacks are widely used in everyday life for carrying loads hands-free. Over time, however, walking or running with a heavy backpack can cause back and neck pain. With that in mind, backpackers in the wilderness (or even those in the city far from a charger) might happily greet such an item. A backpack that collects the mechanical energy of walking. To do what? Of course, to power portable electronic devices or health monitoring sensors.
The old attempts
Previously, the researchers used nanogenerators triboelectrics (TENG) (small devices that convert mechanical energy into electricity) to make an energy-harvesting backpack. but those bags had relatively low power outputs and provided no additional benefits, such as load shedding or shock absorption. Zhong Lin Wang, Jia Cheng and colleagues wanted to design a prototype that would overcome these limitations.
The solutions for the light backpack that generates energy
To save work and absorb shock, the researchers incorporated it into the backpack two elastomers. System which stretch and shrink, keeping the bag in place as the wearer walks. This provided a weight reduction of approximately 20% on the wearer. Meanwhile, the movement between the backpack frame and its load during walking prompted a TENG to convert mechanical energy into electricity, with an efficiency of 14%. The researchers proved that the backpack could power LEDs, an electric clock and fluorescent tubes. Once certain challenges are overcome, such as improving energy conversion efficiency, the backpack has promising potential as a power source for small-scale wearable and portable electronics, GPS and health sensors, the researchers say.
The abstract of the paper is available here.
