Production Techniques for 3D Printed Inflatable Elastomer Structures: Part I—Fabricating Air-Permeable Forms and Coating with Inflatable Silicone Membranes via Spray Deposition

Abstract

Abstract

This article is the first in a two-part series describing a process for conformal three-dimensional (3D) printing on to inflatable substrates. Details for fabricating seamless, tubular elastomeric membranes by spray deposition on a double-curved air-permeable mandrel are presented in Part I. The mandrels are created by casting gypsum into a desired form, and they are made permeable by applying pressurized air to the central core of the gypsum body during its crystallization phase. The membranes—in this case made from silicone—are created by spray deposition onto the mandrel by using a constant surface angular velocity approach. These membranes are inflated so as to impart mechanical pre-strain in the rubber by stretching. The techniques described are particularly suited to the fabrication of 3D printed pneumatic artificial muscles and dielectric elastomer actuators. They can also be used to create removable substrates on which a 3D print can be extruded, or alternatively integrated into a four-dimensional print where varying levels of mechanical strain can be distributed through the various printed layers. Uses for the techniques described include soft robotics, stretchable electronics, biomechanical implants, and custom bioreactors, particularly when combined with direct ink writing techniques.