Penn State team supercharges piezoelectric tech

Created in collaboration with the University of Utah, the device captures energy from the movement of the arm and converts it into enough electricity to power a personal health device. The researchers claim the work is a significant improvement on existing energy harvesting technology that functions in a similar way and could have a range of applications in wearables and IoT.

"The devices we make using our optimised materials run somewhere between five and 50 times better than anything else that's been reported," said Susan Trolier-McKinstry, the Steward S Flaschen Professor of Materials Science and Engineering and Electrical Engineering at Penn State.

Trolier-McKinstry and her former doctoral student, Hong Goo Yeo, used a well-known piezoelectric material, PZT (lead zirconate titanate), and coated it on both sides of a flexible metal foil to a thickness four or five times greater than in previous devices. Increasing the volume of the active material in this way resulted in the generation of more power. The researchers also oriented the film's crystal structure to optimise polarisation, meaning energy harvesting performance was increased. According to Trolier-McKinstry, the compressive stresses that were created in the film as it was grown on the flexible metal foils allowed the PZT films to sustain high strains without cracking, making for more robust devices suitable for wearable electronics.