Stretchable Self-Powered Sensor Achieves 668% Elongation with Stable Signals

A research team led by Professor Miso Kim at KAIST has engineered a highly stretchable piezoelectric fiber sensor that can withstand significant deformation without signal degradation. This development brings wearable medical devices, electronic skins, and soft robots closer to reality by enabling long-term monitoring without external batteries.

Conventional piezoelectric fiber sensors, which convert mechanical pressure into electrical signals, often suffer from electrode and piezoelectric layer damage during repeated stretching or bending, leading to signal instability. While coiling fibers can increase stretchability, maintaining electrical stability has remained a challenge.

The KAIST team implemented a "Hierarchical Resilient Design" strategy, focusing on structural integrity at multiple levels. They embedded elastic polymer microparticles within piezoelectric nanofibers to create an interlocking structure that aids shape recovery, similar to a rubber band. Furthermore, they engineered a seamless interface between the electricity-collecting electrode and the piezoelectric layer to prevent delamination under stress.

This novel design allowed the sensor to be stretched up to 668% of its original length while producing consistent electrical signals across various movements, including stretching, bending, and pressing. The sensor also demonstrated stable operation in coiled and knotted configurations under repeated forces and sudden impacts. AI analysis of the sensor signals enabled accurate differentiation between various movements.

The researchers believe this self-powered sensor platform, which achieves both high stretchability and long-term stability without batteries, has significant potential for next-generation wearable medical devices for continuous biosignal monitoring, as well as for electronic skins and soft robot sensors.