Light-Driven Multidirectional Bending in Artificial Muscles

Using light to drive polymer actuators can enable spatially selective complex motions, offering a wealth of opportunities for wireless control of soft robotics and active textiles. Here, the integration of photothermal components is reported into shape memory polymer actuators. The fabricated twist-coiled artificial muscles show on-command multidirectional bending, which can be controlled by both the illumination intensity, as well as the chirality, of the prepared artificial muscles. Importantly, the direction in which these artificial muscles bend does not depend on intrinsic material characteristics. Instead, this directionality is achieved by localized untwisting of the actuator, driven by selective irradiation. The reaction times of this bending system are significantly - at least two orders of magnitude - faster than heliotropic biological systems, with a response time up to one second. The programmability of the artificial muscles is further demonstrated for selective, reversible, and sustained actuation when integrated in butterfly-shaped textiles, along with the capacity to autonomously orient toward a light source. This functionality is maintained even on a rotating platform, with angular velocities of 6°/s, independent of the rotation direction. These attributes collectively represent a breakthrough in the field of artificial muscles, intended to adaptive shape-changing soft systems and biomimetic technologies.