Abstract
This research describes the design for additive manufacturing (AM) of a pneumatic soft robotic actuator that is uniquely enabled by a novel vat photopolymerization (VPP) AM process. Specifically, the device is a PneuNet style bending mechanism that is designed specifically for a high-viscosity, large-scale VPP AM system. This novel system is capable of fabricating high performance elastomeric materials, such as polydimethylsiloxane (PDMS) loaded with fumed silica nanoparticles or other fillers that result in viscosities too high to be printed with most existing VPP processes. Herein, a tough double network PDMS (DN-PDMS) is designed for printing pneumatic actuators. The mechanical properties of the DN-PDMS, along with the geometric resolution of resulting features, are characterized through experiments, and the results are used to guide the design process of the pneumatic actuator. The results show that the broad design space accessible through the high-viscosity VPP process corresponds with the target geometry identified in this research (determined by maximum bending angle). This design would be challenging or impossible to manufacture using other means; however, this VPP process enables printing of high viscosity materials, large overhangs, internal features, and a fully enclosed hollow structure. Results show that altering the chamber shape and incorporating internal structures leads to a 29.8% improvement in bending angle when compared with the original PneuNet actuator geometry simulated with the same material and pressurization.
