Autonomous Photomechanical Snap-Jumping of Polymer Monoliths

초록

Jumping behavior is a unique motion in natural creatures including mankind to achieve a rapid mobility and to overcome obstacles as well as rough terrains. Owing to these advantages, jumping motion is being applied in various robotic systems in order to mimic natural creatures, especially insects. Toward miniaturized jumping robots, the introduction of a remote powering system is desirable to avoid on-board weight penalty of an internal power system. We synthesize liquid crystalline polymer networks (LCNs) self-assembled along with photo-responsive molecular switch. Upon actinic light irradiation, the unprecedented photomechanical jumping of the LCN monolith is generated by an instantaneous photo-induced energy release. A twisted nematic geometry of LCNs provides bistable non-isometric structures, resulting in sufficient photo-induced energy accumulation to overcome their body mass. The experimental jumping behavior is supported by a finite element method (FEM) simulation for quantitative analysis. The jumping capability of the photo-responsive LCN monolith reaches 15.5 body length (BL) of jumping height, and 880 BL/s of maximum take-off velocity. In addition, we demonstrate angle and height controlled bi-modal jumping by programming macroscopic geometry and light intensity profile. Finally, the controlled light irradiation provides continuous and directed jumping of LCN monolith to hurdle the obstacle within a few seconds.