4D Multimaterial Printing of Soft Actuators with Spatial and Temporal Control

Abstract Soft actuators (SAs) are devices which can interact with delicate objects in a manner not achievable with traditional robotics. While it is possible to design a SA whose actuation is triggered via an external stimulus, the use of a single stimulus creates challenges in the spatial and temporal control of the actuation. Herein, a 4D printed multimaterial soft actuator design (MMSA) whose actuation is only initiated by a combination of triggers (i.e., pH and temperature) is presented. Using 3D printing, a multilayered soft actuator with a hydrophilic pH‐sensitive layer, and a hydrophobic magnetic and temperature‐responsive shape‐memory polymer layer, is designed. The hydrogel responds to environmental pH conditions by swelling or shrinking, while the shape‐memory polymer can resist the shape deformation of the hydrogel until triggered by temperature or light. The combination of these stimuli‐responsive layers allows for a high level of spatiotemporal control of the actuation. The utility of the 4D MMSA is demonstrated via a series of cargo capture and release experiments, validating its ability to demonstrate active spatiotemporal control. The MMSA concept provides a promising research direction to develop multifunctional soft devices with potential applications in biomedical engineering and environmental engineering.