3D Printing PDMS Elastomer in a Hydrophilic SupportBath via Freeform Reversible Embedding

摘要

Polydimethylsiloxane (PDMS) elastomer is used in a wide range of biomaterial applications including microfluidics, cell culture substrates, flexible electronics, and medical devices. However, it has proved challenging to 3D print PDMS in complex structures due to its low elastic modulus and need for support during the printing process. Here we demonstrate the 3D printing of hydrophobic PDMS prepolymer resins within a hydrophilic Carbopol gel support via freeform reversible embedding (FRE). In the FRE printing process, the Carbopol support acts as a Bingham plastic that yields and fluidizes when the syringe tip of the 3D printer moves through it, but acts as a solid for the PDMS extruded within it. This, in combination with the immiscibility of hydrophobic PDMS in the hydrophilic Carbopol, confines the PDMS prepolymer within the support for curing times up to 72 h while maintaining dimensional stability. After printing and curing, the Carbopol support gel releases the embedded PDMS prints by using phosphate buffered saline solution to reduce the Carbopol yield stress. As proof-of-concept,we used Sylgard 184 PDMS to 3D print linear and helical filamentsvia continuous extrusion and cylindrical and helical tubes via layer-by-layerfabrication. Importantly, we show that the 3D printed tubes were manifoldand perfusable. The results demonstrate that hydrophobic polymerswith low viscosity and long cure times can be 3D printed using a hydrophilicsupport, expanding the range of biomaterials that can be used in additivemanufacturing. Further, by implementing the technology using low costopen-source hardware and software tools, the FRE printing techniquecan be rapidly implemented for research applications.