Wearable tech is getting smaller and smarter, but making self-powered sensors that fit easily onto large surfaces is difficult. Older sensors couldn’t adjust their sensitivity well, and they took up too much space.

A research team led by Associate Professor Jaekyun Kim at Hanyang University in South Korea developed a new method to build these devices. Instead of spreading the components out, they stacked the sensor parts vertically.

Stacking the Tech

The layered tech has a top layer that senses touch, a middle layer that acts as an insulator, and a bottom transistor layer that controls the baseline power.

When a steel plate touches the top layer and pulls away, it leaves a small electric charge. Then, when an object approaches the surface again, the sensor’s power level shifts. This change tells the device exactly how close the object is. The sensor also detects when something presses harder because a wider contact area produces a stronger electrical response. By adjusting the bottom layer’s voltage, researchers can easily tune the device’s sensitivity.

“Our vertical dual-gate architecture not only offers gate-tunable amplification of the triboelectronic responses, but also minimizes pixel footprint, enabling high-density, large-area integration,” Dr. Kim explained.

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Real-World Testing

Photo: aerogondo2/Shutterstock

The team built a 10-by-10 grid of these sensors. It easily detected bare-finger touches and could even sense a steel probe up to 500 micrometers away.

The sensor reacted in just 127 milliseconds and recovered in 212 milliseconds. Plus, it handled 1,000 uses without any drop in performance.

“Our research could contribute to the development of electronic skin systems that allow robots, prosthetic devices, and wearable electronics to perceive touch, pressure, and proximity more precisely,” Dr. Kim added. “This will lead to safer and more reliable human–machine interaction, with applications in healthcare robots, health monitoring, and autonomous systems.”