Wood-derived materials can be used to harvest electrical energy from everyday movements such as walking, according to a new study from researchers at U of T Engineering and the University of Waterloo.
In a paper recently published in Nano Energy, the team demonstrated the use of lignocellulosic nanofibrils, derived from tree bark, in a prototype self-powered device capable of sending a wireless signal to a smartphone via Bluetooth.
Such devices can be used to track biometric data such as heart rate, oxygen levels or skin conductivity. The innovation could improve the performance of these devices while lowering their environmental impact.
“Biosensors are common in wearable electronics, but today they are powered by batteries,” says Professor Ning Yan (ChemE), final author on the new paper.
“This makes them bulky, inconvenient and costly. Sensors without batteries could be thinner, smaller and cheaper. You would never again have to worry about forgetting to charge the battery. You could just stick it on your skin, and it would be powered by your natural movements.”
The principle behind the innovation is the trioboelectric effect, a form of static electricity. Because some materials attract electrons more than others, repeatedly bringing two different materials in contact and then separating them can cause an electrical charge to build up between them.