Design and fabrication of multi-material pneumatic soft gripper using newly developed high-speed multi-material vat photopolymerization 3D printer

This study proposes a versatile, low-cost, shape-conforming soft gripper fabricated using the self-developed high-speed multi-material vat photopolymerization process. This additive manufacturing technology consists of a rotary build plate that moves through 180 degrees along the XY plane and multiple resin vats to accommodate different materials. A cleaning system uses pressurized air and alcohol to prevent contamination between layers and to increase the bond strength. The soft grippers are manufactured using soft (GC3D-ESK) and hard phase (AA-temp) materials to optimize the gripping force and prevent damage of the objects. Experimental results show that the tensile strength of the multi-material fabricated part (GC3D-HSK and AA-temp) is 5 times greater than that of the soft material GC3D-HSK. The multi-material specimen exhibits an elastic modulus of 89.28 MPa, which is much higher than 2.08 MPa of the soft material. The multi-material fabricated specimen exhibits high strength, high elastic modulus, and 65% longer elongation than the hard material. In addition, the specimens that are cleaned with alcohol after successive printing of each layer have 4% higher tensile strength and 30% longer ductility. A shrinkage analysis is carried out to evaluate the material compatibility. The percentage shrinkage for both GC3D-HSK and AA-temp is obtained in the range of 0.1-0.2%. The printed pneumatic soft gripper is used to lift goods of up to 200g using a maximum pressure of 34.3 kPa. The lifting efficiency of the developed gripper is evaluated to be 5.83 g/kPa which is higher than the currently existing grippers. The printed gripper can lift objects of different weights and profiles without damaging the surface. The high-speed multi-material VP 3D printer can be used for additive manufacturing to optimize the design of pneumatic soft grippers.