Performance Evaluation and Optimization of an Ink/Polyurethane Actuator for Light-Driven Soft Gripper

Flexible light-driven actuators are emerging as critical components for next-generation soft robotics and intelligent systems, demanding simple fabrication and robust performance. This work details the optimization and characterization of a flexible, low-cost light-driven actuator based on an ink/polyurethane bilayer composite. We maximized the actuation performance, including bending angle and response speed, by systematically tuning the ink concentration and polyurethane layer thickness. Optimal results were achieved at an ink concentration of 220 mg/mL and a polyurethane thickness of 50 µm, which thermal analysis confirmed is due to an ideal balance between photothermal efficiency and mechanical integrity. The actuator also exhibited excellent durability, showing no performance degradation after 500 continuous cycles. Our results validate this material system for applications like soft grippers and offer clear design principles for enhancing photothermal actuator performance.