KAIST Develops Light-Responsive Soft Robot Hand Material

Recap

Source: 헬로디디, report of Sept. 30, 2026

According to the report, a research team led by Professor Moon Hong-cheol from KAIST’s Department of Biochemical Engineering has developed a new ion-based soft robot material called 'Ionograsper.' The material is designed to sense nearby objects and react to light by changing its shape. The team combined azobenzene, which changes form when exposed to light, with a polymer that absorbs moisture from the air. This combination creates a soft material where ions can move internally.

When a charged object approaches, the material detects it without direct contact. The internal arrangement of positive and negative ions shifts, generating an electrical signal that indicates the object's presence and movement. This sensing function works without the need for an external voltage source. To grasp an object, the material is exposed to ultraviolet light. This causes the azobenzene molecules to change structure and moisture to leave one side of the material, causing it to bend and clasp the object.

The material can maintain its bent shape for more than 10 minutes after the light is turned off. This is because the polymer structure relaxes slowly, allowing the material to hold onto an object without continuous illumination. The research team stated that this approach reduces the need for separate sensors, actuators, and wiring in soft robot hands. They plan to expand the technology to work with visible or near-infrared light and integrate it with AI control.

Context

Soft robotics has traditionally relied on integrating separate electronic sensors and actuators into flexible bodies. This often adds complexity, weight, and fragility to the system. The Ionograsper approach represents a shift toward 'intrinsic' sensing and actuation, where the material itself performs these functions. This is similar to how biological tissues, such as skin and muscle, work together in a unified structure. The inspiration from the Venus flytrap, which closes its leaves in response to stimuli, highlights the biomimetic design of the material.

Robot's take

This development is significant for creating more robust and simpler soft robotic grippers. By eliminating separate electronic components, the system may be more durable and easier to manufacture. However, the current reliance on ultraviolet light for actuation is a limitation, as UV can be harmful and is not always practical in real-world environments. The team's plan to use visible or near-infrared light is a promising next step. It remains to be seen how well this material will perform in complex, multi-object grasping tasks or in the presence of varying humidity levels, which could affect the moisture-absorbing polymer. The integration with AI control will be crucial for making this technology useful in dynamic, real-world applications.