Shape morphing smart 3D actuator materials for micro soft robot

Abstract: Stimuli-responsive materials have been used in major applications such as sensors, actuators, wearable devices, and biomedical devices owing to their ability to respond to external stimuli including heat, light, electricity, humidity, and chemicals. Strategies to trigger the stimuli-responsive, shape-morphing of two-dimensional (2D) sheets into three-dimensional (3D) shapes are of significant interest for a variety of smart applications including soft robotics. Stimuli-responsive properties can be designed by the selection of materials, structures, and processing methods. This review outlines seven broad categories of stimuli-responsive 2D soft materials for 3D smart actuator applications, namely (1) carbon nanomaterials, (2) metal nanomaterials, (3) shape memory polymers, (4) liquid crystal polymers and elastomers, (5) azobenzenes, (6) hydrogels, and (7) bio-hybrids, along with their basic mechanisms, processing methods, and applications.