As wearable health tech proliferates, the search for alternative power sources intensifies. The fast and easy answer for better energy sources for wearables, carryables, and implants is to build find more efficient batteries. However, the pace of new energy cell development is slow. Researchers at Clemson University developed an energy harvesting technology from conductive plastics activated by walking or tapping. Scientists from the Fraunhofer Institute and others worked with thin-film piezoelectric material used in energy-harvesting in small wearables.

Engineers from the Department of Mechanical and Automation Engineering at The Chinese University of Hong Kong (CUHK) published a design for a macrofiber composite (MFC) energy harvester that captures biomechanical energy from the human knee. Two MFC slices are attached to a flexible beam. The knee joint’s rotational motion is transformed to linear motion by a slider-crank mechanism, and then the bending beam creates a second transformation from linear to bending motion. The bending motion deforms the attached MFC slices which generates electrical energy. According to the research team, a lightweight harvester can generate up to 1.60 mW of electrical energy with no added human effort. The engineers tested the device with humans walking on a treadmill at various speeds and with different amounts of resistance.

Expounding on the potential biomechanical energy harvesters, the CUHK researchers said the power sources could produce sufficient energy to power wireless health equipment, electronic watches, and mobile phones.