Gel-based soft actuators driven by light

Movement is essential for living organisms. Biological motors enable activities necessary for life by conversion of chemical energy. Controlling stimuli-induced molecular motion and mastering its amplification from the molecular to the macroscopic scale enables the preparation of synthetic materials that display motile response and life-like actions such as bending, twisting and expansion-contraction movements. Light represents a valuable stimulus that can be remotely applied with high spatiotemporal control. Herein, photoresponsive gels that perform light-driven actuation are highlighted. Although some limitations still need to be overcome, these fascinating materials may find potential applications in remotely-guided bio-medical devices, artificial muscles, smart drug delivery systems, microfluidic elements, micromanipulators and biologically-inspired soft robotics.