Multi-material 3D-Printer for Rapid Prototyping of Bio-Inspired Soft Robotic Elements

Abstract

A rising trend can be observed in robot development towards the usage of flexible materials, whose properties resemble their biological counterparts. This way of design promises machines that are more adaptive, energy efficient and cost effective. One of the biggest challenges in this growing research field is the fabrication of functional elements, which consist of several embedded materials. The lack of compatible substances and of a proper prototyping technology limits the possible complexity and the degree of automation in prototyping. Furthermore, additive manufacturing techniques are usually designed for predefined purposes and do not have the customizability the research in an innovative field requires. In order to address this problem a novel multi-material 3D-printer with on-demand tool change has been developed. The adaptive locking mechanism in combination with a kinematic coupling allows the device to switch between tools varying in the dispensed material and even work principle. Using specifically developed directly driven filament-print-heads, a series of test specimen has been fabricated. The very reliable and precise extrusion, even of highly flexible material, is demonstrated in form of airtight chambers utilized as pneumatic actuators. In an additional demonstrator the flexible part has been reduced to a single expandable membrane as the active element included in an otherwise stiff housing. A specific design made it possible to embed the membrane in the surrounding, which compensated for the lack of chemical bonding between both substances and created a pneumatic actuator with a much better stability/performance ratio. These demonstrators highlight the great potential to create yet unbuilt biomimetic structures and multi-material systems with this novel multi-material printer.