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

Abstract

This article is the first in a two-part series describing a process for conformal 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 made permeable by applying pressurised air to the central core of the gypsum body during its crystallisation phase. The membranesin this case made from siliconeare created by spray deposition onto the mandrel 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 fabrication of 3D printed Pneumatic Artificial Muscles (PAM) and Dielectric Elastomer Actuators (DEA). They can also be used to create removable substrates upon which a 3D print can be extruded, or alternatively integrated into a 4D 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.

Additive Manufacturing of Multi‐Scale Porous Soft Tissue Implants That Encourage Vascularization and Tissue Ingrowth

“…To maintain a constant velocity in the underlying substrate, a Constant Linear Velocity (CLV) approach was used. [ 24 ]…”

“…To maintain a constant velocity in the underlying substrate, a Constant Linear Velocity (CLV) approach was used. [24] In a second application (coating a mammary implant), we coated the gypsum form of a human breast with a 250 µm thick silicone membrane (Figure 3G-I). The substrate curvature was measured using a laser [25] and a spray deposition toolpath was derived, ensuring that the nozzle tip is maintained at 85 mm from the surface.…”

“…We print open-pore structures over highly curved surfaces, using multi-axis printing techniques. Building upon pre-existing principles, [24,25] we show that a substrate can be coated by first ascertaining the surface topology using laser measurements, and then calculating a toolpath over that surface -resulting in an evenly distributed coating. This shows that varying LRC loops can be used to completely coat complex shapes.…”

Bioinspired Heart Valve Prosthesis Made by Silicone Additive Manufacturing

“…The spraying duration was adjusted to generate leaflets with controlled thicknesses of 200 or 300 mm after curing. 41 Stripes of medium-stiffness silicone were sequentially deposited on the surface of the three sprayed leaflets using extrusion-based printing via DIW ( Figure 4C). The medium-stiffness silicone exhibits Shore hardness and apparent elastic modulus of 73 A and 4.3 MPa, respectively.…”

Enhanced stretchable electronics made by fused-filament fabrication

“…3D printing allows the easy fabrication of complex module geometries and support structures for interconnects. The available literature describes many approaches for 3D-printed electronics, but no practical application in the domain of wearable stretchable electronics with fused-filament fabrication (FFF) has been presented [5][6][7][8][9][10].…”