An Environment-Powered Soft Actuator Enabled by Water and Light Highly Absorptive Nanoforests

Soft robots driven by ambient energy have garnered significant attention. As core components of soft robots, soft actuators often suffer from unstable mechanical properties, complex fabrication processes, and restricted driving modes. Here, we present a soft actuator constructed from a composite nanofilm comprising aluminum (Al)-coated nanoforests (Al@NFs), Nylon-6 (PA6), and Al. Benefiting from the superhydrophilicity (with a contact angle of 8° and water spreading within 0.2 s) and high light absorption (average of 85% in a spectrum covering from visible to infrared) of the Al@NFs, the actuator achieves rapid and reversible deformation under both humidity and light stimuli, enabling dual-mode actuation. The actuator exhibits response rates of 23.06°/s to excessive humidity and 4.02°/s to 310 mW cm –2 laser irradiation, respectively. A thermal response time of approximately 4 s and a bending angle temperature coefficient of 3.607°/K are demonstrated, which outperform the existing actuators. Moreover, by leveraging the intrinsic anisotropy of PA6, programmable deformation behavior and diverse gripper geometries are achieved. Based on this actuator, we further demonstrate applications such as biomimetic flowers, miniaturized cranes, and dual-controllable switches. This dual-driven actuator offers versatile environmental energy conversion and holds broad potential for advancing soft robotic systems.