Transparent photoactuators based on localized-surface-plasmon-resonant semiconductor nanocrystals: a platform for camouflage soft robots

Among the various kinds of actuators, photoactuators with the advantages of wireless and remote manipulation arouse the interest of many researchers. However, it is challenging to develop transparent photoactuators for camouflage soft robots, because most of current photoactuators use colored or even black light-absorbing agents. Here, we fabricate a series of transparent actuators by employing localized-surface-plasmon-resonant semiconductor nanocrystals, which mainly response to infrared light. In this way, we introduce the advantages of wireless and remote manipulation into the camouflage soft robots. Three semiconductor nanocrystals (In2O3:Sn, W18O49 and CuS nanocrystals) are fabricated as the photothermal converting agents to construct photoactuators. Owing to the weak absorption of visible light, the fabricated actuators exhibit high transparency (maxium transmittance >72%, at 600 nm). Meanwhile, they demonstrate remarkable deformations upon near infrared light irradiation (curvature up to 0.66 cm-1). Finally, a worm-like crawling robot, a glasswing butterfly robot and a two-finger robot hand are constructed to demonstrate the ability of remote manipulation and inconspicuousness in both the robot appearance and the driving signal, attaining excellent passive camouflage function. These results provide a promising platform for remote-controlled camouflage soft robots and bio-mimic applications, which will be of significance in the field of soft robotics.