Solvent responsive single-material inverse opal polymer actuator with structural color switching.

Single-material flexible actuators that can produce non-uniform deformation in response to external stimuli have attracted considerable interests due to their facile fabrication process and excellent actuation behavior. However, the recognition of actuation state with easily perceived and detectable signal is still a challenge. In this paper, we report an actuator behavior of single-material inverse opal photonic crystal films, which are in response to a variety of solvents based on swelling/de-swelling process. The actuator exhibits improved responsiveness due to the enhanced mass transport of solvent molecules in periodic inverse opal with macroporous structure. Especially, peaks in reflective spectra and corresponding structure colors are obviously changed, providing a simple and effective optical technology for optical recognition of micro-locomotion. Based on the above characteristics, we demonstrate the potential applications of this photonic crystal actuator as solvent-driven gripper, walking device and rolling motor, showing great promise in advanced soft robot for many important intelligent areas. [ABSTRACT FROM AUTHOR]