Jeonbuk National University, KAIST researchers develop soft robot

A joint research team from Jeonbuk National University and the Korea Advanced Institute of Science and Technology (KAIST) has developed an ionic soft robot called the Ionograsper that can detect nearby objects and grasp them in response to light.

The findings were published in the international journal Advanced Materials, and the paper was selected as a cover article. The study is titled “A Multifunctional Ionograsper Enabling Ion-Redistribution Proximity Sensing and Structural-Reconfiguration-Driven Bidirectional Actuation.”

Jeonbuk National University said Thursday that the research was led by Kim Yong-min, a professor at its School of Chemical Engineering, and Moon Hong-chul, a professor in KAIST’s Department of Chemical and Biomolecular Engineering.

The university noted that the key innovation lies in a single soft material that serves as both a sensor and an artificial muscle.

The robot can be activated by brief exposure to low-intensity ultraviolet light and retains its deformed shape for more than 10 minutes after the light is switched off, without requiring further energy input.

“The material can grasp an object and maintain its grip after just a brief light stimulus, potentially reducing the structural complexity and energy demands of robots,” Kim said.

He said his team plans to further develop the material for physical artificial intelligence (AI) robots that interact flexibly with people and objects by integrating it with AI-based control technologies.

Conventional soft robots often rely on separate sensors to detect their surroundings and actuators to generate movement. This separation increases the number of components and wires, complicating system design. Such robots may also require a continuous energy supply to move or maintain a particular posture.

To address these limitations, the research team integrated sensing and actuation into a single ionic polymer material.

The robot detects approaching objects by monitoring ion redistribution within the material. When a charged object comes close, its electric field alters the ion distribution, generating an electrical signal.

This allows the robot to detect approaching objects without a dedicated power supply for the sensing function.

Movement relies on the material’s response to light and moisture. When exposed to low-intensity ultraviolet light, azobenzene molecules in the material undergo a light-induced structural change. This triggers moisture evaporation and the formation of nanoscale pores on the surface.

This restricts the movement of polymer chains, temporarily stabilizing the material’s altered structure. Once the light is switched off, the material reabsorbs moisture at different rates on its two sides, causing it to bend in the opposite direction. The polymer structure then gradually relaxes, eventually allowing the material to return toward its original shape.

The research team incorporated these properties into the Ionograsper, a soft robot inspired by the Venus flytrap’s sensing and trapping mechanisms.

After detecting an approaching object, the Ionograsper grasps it when exposed to ultraviolet light. It maintains its grip without further energy input and eventually releases the object as its internal structure gradually relaxes.

The findings could help advance materials for physical AI robots designed to interact with people and objects in real-world environments.