This 3D printing support bath holds extruded material in a hydrophobic suspension that has strong thermal stability, enabling freeform fabrication of complex hydrophobic structures from inks with varying cross-linking or solidification requirements. The global market for 3D printing should exceed $23 billion by 2025. Freeform 3D printing of functional structures via extrusion is popular due to its easy implementation, high efficiency, and compatibility with a wide range of printable materials. However, in order for the printed object to retain its shape, conventional 3D extrusion printing techniques require either support scaffolds or rapidly solidifying or self-supporting materials, which can limit the selection of printable materials and probably weaken the physical or mechanical properties of the final object. Other techniques retain the printed shape by using support baths. These baths are typically hydrophilic, however, which can distort extrusion of fine features when printing complex hydrophobic structures. Available hydrophobic support baths are sensitive to temperature changes and lose supporting function at increased operating temperatures, limiting potential printing applications of certain polymers and other materials that cross-link or solidify at higher temperatures.
Researchers at the University of Florida have developed a hydrophobic support bath for 3D printing freeform structures from hydrophobic printing materials. The bath preserves proper extrusion of finer features when printing from hydrophobic inks and exhibits thermal stability to maintain supporting functions at higher cross-linking or solidification temperatures.
3D printing of complex hydrophobic functional components that advance fields such as soft robotics, wearable sensing, bioprocessing, and microfluidics
The yield-stress support bath material consists of fumed silica nanoparticles dispersed in a volume of mineral oil. A hydrophobic ink deposits into the fumed silica suspension via a 3D printing extrusion nozzle and retains its structural shape during printing. The bath holds it in place until the whole structure is complete. This intermediate structure may remain liquid or only partially solidify after printing. It then receives heat, ultraviolet radiation or other cross-linking mechanisms to initiate cross-linking until it completely solidifies to form the finished article. This hydrophobic support bath facilitates printing of complex 3D structures from various hydrophobic inks such as polydimethylsiloxane (PDMS), SU-8 resin, and epoxy-based conductive inks. The bath also has strong thermal stability and UV transparency to support different cross-linking mechanisms for curing various hydrophobic ink materials.
