Structural Color Surface on Transparent PDMS Fabricated by Carbon-Assisted Laser Interference Lithography for Real-Time Quantification of Soft Actuators Motion.

Dynamic and real-time monitoring of the motion state of soft actuators is of great significance for optimizing their performance. However, present noncontact measurement approaches based on diffractive groove arrays fabricated by imprinting have some limitation, e.g., the grooves should be processed before the solidification of soft materials or the depth and period of grooves cannot be flexibly adjusted. Here, a flexible and high-efficiency fabrication approach carbon-assisted laser interference lithography (CLIL) for periodical groove structures with structural color is proposed. This technique is to irradiate the interference laser on the PDMS surface coated by a carbon layer, which is used for enhanced laser absorption. The processing parameters are systematically studied and optimized to achieve a bright structural color. Benefiting from the advantages of CLIL, the structural color can be processed on a solidified transparent surface with controllable characteristics such as groove period and depth. Lastly, the motion of an electric-driven actuator can be real-time quantified by calibrating the relationship between the observation angle and the observed structural color.