Imagine wearing a lightweight patch that can monitor your heartbeat, breathing and movements for long periods without ever needing a battery.
Or imagine robots with soft, flexible skins that can feel pressure and movement much like human skin.
These ideas may be closer to becoming reality thanks to a new self-powered sensor developed by researchers at the Korea Advanced Institute of Science and Technology (KAIST).
The newly developed sensor can stretch up to 668% of its original length—almost seven times longer than it starts out—while continuing to produce stable electrical signals.
Even after repeated stretching, bending and pressing, the device keeps working reliably.
The sensor is made from a special material called a piezoelectric polymer. Piezoelectric materials can generate electricity when they are squeezed, stretched or bent. This means the sensor can power itself using movement and does not need a battery.
Because these materials are lightweight and flexible, they are considered ideal for wearable medical devices that stick to the skin.
However, previous piezoelectric sensors have faced a major problem. After repeated movement, the layers inside the sensor can become damaged, causing the electrical signals to weaken or fail.
Researchers have been trying to solve this issue for years. While coiling the fibers can make sensors more stretchable, maintaining stable electrical performance during constant movement has remained difficult.
The KAIST team addressed this problem by creating what they call a “Hierarchical Resilient Design.” The idea is to make every level of the sensor—from the materials to the structure itself—better able to withstand repeated deformation.
The researchers added tiny elastic polymer particles inside the sensor fibers. These particles act somewhat like Velcro, helping the fibers hold together and return to their original shape after being stretched repeatedly.
The team also strengthened the connection between the layer that generates electricity and the electrode layer that collects the electrical signals. By creating a stronger bond between these layers, they prevented them from separating during stretching or bending. As a result, the sensor maintained stable performance even under extreme deformation.
Tests showed that the sensor could reliably generate electrical signals while being stretched, bent and pressed. The researchers also created versions of the sensor in different shapes, including coiled and knotted designs, and found that they continued to function well even after repeated forces and sudden impacts.
The team further combined the sensor with artificial intelligence. By analyzing the electrical signals, the AI system could accurately distinguish between different types of movement, such as pressing, bending and stretching.
The research could have important applications in health care and robotics. Self-powered sensors that do not require batteries could lead to comfortable wearable devices that continuously monitor heart rate, breathing, joint movements and muscle activity over long periods.
The technology may also help create electronic skins and soft robots that can sense their surroundings more naturally. By combining extreme flexibility with reliable performance, the new sensor represents an important step toward lighter, smarter and more practical wearable technologies.
