Near-infrared light-driven locomotion of a liquid crystal polymer trilayer actuator

A new and general design is demonstrated for a liquid crystal polymer network (LCN)-based actuator to perform near-infrared (NIR) light-guided locomotion. The actuator is a structured trilayer, comprising a thin reduced graphene oxide (RGO) top layer, an inactive polymer middle layer and an active LCN bottom layer. Exposing the RGO side to a moving NIR laser, a moving wave along the strip actuator is generated, which makes the strip an effective caterpillar walker whose light-driven locomotion has appealing attributes. On one hand, in contrast to most LCN-based actuators that move on a ratcheted substrate surface or need a supporting plastic frame, the trilayer actuator moves on either horizontal or inclined untreated surfaces. On the other hand, while known actuators using the photothermal effect are usually prepared by mixing the nanofiller used as a NIR light heater with the polymer, which may reduce the reversible deformation degree and increase the compatibility concerns, the easy trilayer fabrication method laminates directly a “sheet” of RGO on thick polymer layers, which circumvents the potential problems.