Development of Bioinspired 4D-Printed PLA Grippers

This paper presents two designs of polylactic acid (PLA) grippers. The two designs use hand-like structures that have four fingers for gripping. Design 1 uses longitudinal-transversal printed lines to bend the fingers. The fingers have identical dimensions of 1 mm × 4 mm × 15 mm for the height, width, and length, respectively. Meanwhile, Design 2 uses a bioinspired design concept to optimize the gripping performance, where honeycombs are used as a source of inspiration. The fingers are designed with height, width, and length of 1.4 mm × 15 mm × 50 mm, respectively. The grippers are fabricated using fused deposition modeling (FDM)-based four-dimensional (4D) printing. Deformation of the fingers is achieved by activating the grippers using the temperature of the hot water, which releases the induced strain that is stored in the PLA during the printing process. The FDM printing parameters are controlled to optimize the levels of the induced strain in the fingers of the gripper. The transient responses of the grippers are analyzed using Kinovea software and MATLAB. The magnitude values of the deformation Designs 1 and 2 are ~10 mm and ~41.38 mm, while their settling time values were respectively 2.93 s and 7.46 s. The proposed grippers demonstrated their ability to grip different objects inside and outside hot water. The results show that the proposed designs are suitable for different robotics applications, especially underwater object manipulation.