Innovative adhesive film harvests electricity from peeling, enabling battery-free sensing and safety

A new ultra-thin, transparent film, developed by researchers at UNIST can generate electrical signals solely through mechanical peeling or pressing actions. This technology paves the way for smart sensors that operate without batteries, with potential applications in safety, security, and industrial monitoring.

The film leverages the principle of frictional electricity—where charge transfers occur when two materials contact and then separate—to produce electrical signals during routine mechanical movements.

By integrating carefully designed cut patterns into an adhesive film, Professor Hoon Eui Jeong and his research team in the Department of Mechanical Engineering at UNIST have created a self-powered sensor capable of converting mechanical stimuli into detectable electrical outputs, while also controlling adhesion strength.

Featuring a pattern of cuts shaped like the Korean alphabet “ㄷ,” the film achieves more than 35 times higher adhesion and roughly 13 times greater electrical output compared to conventional designs. This allows it to generate strong electrical signals from simple, short actions like pressing or peeling.

Hee Jin Lee, the first author of the study published in Advanced Functional Materials, explained, “The specific cut pattern guides crack propagation, enabling rapid and controlled separation that maximizes electrical output. When a crack halts at a junction and then resumes moving in the opposite direction, it produces a significant electrical signal.”

Moreover, by tuning the orientation and arrangement of the cut patterns, the film’s electrical and adhesive responses can be customized based on the direction or location of peeling—adding a programmable dimension to its functionality.

The researchers demonstrated practical applications, such as attaching the film to a door frame to generate a signal upon opening, which can activate a warning system. They also developed a system that detects the peeling of a picture frame before it falls, sending alerts to smartphones. Additionally, when applied to a conveyor belt, the film only generates signals during reverse rotation, enabling early detection of abnormal machinery operation and automated shutdowns.

Professor Jeong stated, “This technology transforms a simple adhesive film into a smart, self-generating sensor that requires no batteries. Its versatility makes it suitable for various fields, including wearable sensors, theft prevention, and industrial safety systems.”