Wearable energy harvester achieves 280 times efficiency boost

A team led by Prof. Jang Kyung-In from the Department of Robotics and Mechatronics Engineering (DGIST) has developed a three-dimensional stretchable piezoelectric energy harvester that can harvest electrical energy using body movements. The device is to be used as a wearable energy harvester as it can be attached to the skin or clothes.

The work is published in the journal ACS Nano.

Energy harvesters are of two types based on whether they work on the triboelectric effect or piezoelectric effect. The device developed by Prof. Jang’s team is based on the piezoelectric effect, which produces electricity from physical activities such as elastic skin or joint movements.

The literature contains several studies that have focused on piezoelectric energy harvesters, but most of them use organic or composite-based piezoelectric materials, which have low energy efficiency. This made it difficult to harvest enough power from body movements, limiting their use as wearable energy devices.

The device developed by Prof. Jang’s team is based on the lead zirconate titanate (PZT), which has a high piezoelectric efficiency. PZT has excellent piezoelectric performance but is hard and brittle, making it difficult to use it as a stretchable device. However, Prof. Jang’s team designed PZT into a three-dimensional structure that is insensitive to deformation, ensuring high energy efficiency and stretchability at the same time.

They also introduced a new curvature-specific coupling electrode design to divide the electrodes into different sections so that the electrical energy of the device is not canceled out. This led to an energy efficiency that is 280 times higher than that of conventional stretching piezoelectric energy harvesters.

“Developing this highly efficient stretchable piezoelectric energy harvester technology is a major achievement of this research,” said Prof. Jang. “We expect this technology to become useful after commercialization and lead to the practical use of wearable energy harvesters.”