3D printing of a photo-thermal self-folding actuator

The demand for rapid and accurate fabrication of light-weight, biocompatible, and soft actuators in soft robotics has perused researchers to design and fabricate such products by rapid manufacturing techniques. The self-folding origami structure is a type of soft actuator that has applications in micro electro mechanical systems, soft electronics, and biomedical devices. 3-dimentional (3D) printing is a current manufacturing process that can be used for fabrication of involute soft self-folding products by means of shape memory polymer materials. This paper presents, for the first time, a method for developing a photo thermal self-folding soft actuator using a 3D bioplotter. Easily accessible and inexpensive pre-strained polystyrene is opted for the backbone of actuator. The polystyrene film (PS) is then structured in a hand shape gripper. Chitosan hydrogel and carbon black ink were combined for printing active hinges on the hand gripper. Various active hinges with different widths and thicknesses were printed on the hand gripper using the 3D bioplotter. An infra-red (IR) heating lamp was placed at a reasonable distance to emit IR light uniformly on the hand gripper. The temperature distribution on the hand gripper was observed using a thermographic camera and the bending angles of the samples were recorded by a video camera. It was observed that the bending angles of the hand fingers depend on factors such as the intensity of the heat flux generated by the IR light intensity, distance, onset temperature, geometry of the fingers such as width and thickness, and area of the hinges.