Self-regulated photoresponsive heterogeneous PNIPAM hydrogel actuators

Abstract

Self-regulated actuators harness material intelligence to enable complex deformations and dynamics, representing a significant advancement in automated soft robotics. However, investigations on self-regulated soft actuators, particularly those using simplified actuation modules such as unidirectional light beam, remain limited. Here, we present a design paradigm for self-regulated actuators based on Poly(N-isopropylacrylamide) (PNIPAM) heterogeneous hydrogel, where self-regulated deformations are actuated by a fixed near-infrared laser. By utilizing the different responsiveness of PNIPAM hydrogels and those integrated with reduced graphene oxide (rGO), we develop three heterogeneous hydrogel configurations: up-down, side-by-side, and hybrid. These designs enable complex biomimetic deformations in soft hydrogel actuators, resembling a bending finger or a flexible industrial manipulator, all actuated by a single fixed laser source. These proposed heterogeneous designs and actuation strategies leverage material intelligence to create soft actuators with enhanced autonomy, paving the way for soft automation, adaptive systems, and biomedical applications.