Hydrostatic 3D-printing for soft material structures using low one-photon polymerization

Abstract

This paper studies the feasibility of a 3D printing method that enables a hydrostatic condition for supportfree fabrication, named hydrostatic 3D printing (H3P). Soft structures are difficult to build in additive manufacturing due to the low stiffness. H3P utilizes low one-photon polymerization (LOPP) to achieve "inliquid" curing surrounded by the hydrostatic pressure. Single-spot curing and continuous printing were investigated for a UV-curable silicone material under different light intensities and exposure times. Initial results have demonstrated LOPP effects for H3P. The equivalent exposure time in continuous printing was found shorter than a stationary single-spot curing due to a non-linear intensity distribution.

Additive Manufacturing of Overhang Structures Using Moisture-Cured Silicone with Support Material

“…Hamidi et al [16] used melted sugar as a support material to print silicone, but could only achieve limited dimensional and geometrical accuracy. Some research groups attempted to develop a hydrostatic AM process to create support-free soft structures [17][18][19][20]. One form of this process is extruding the print material inside a vat of another viscous material with a similar density, which acts as the support structure [18,20].…”

“…Some research groups attempted to develop a hydrostatic AM process to create support-free soft structures [17][18][19][20]. One form of this process is extruding the print material inside a vat of another viscous material with a similar density, which acts as the support structure [18,20]. The hydrostatic pressure of the fluidic media physically stabilizes the printed soft material in a desired location [19].…”

“…Due to the hydrostatic pressure inside the vat, the shape and the position of the printed part will be maintained without any support structures. Kim et al [20] developed a system to additively manufacture UV curable silicone while the part is floating in the middle of the vat and does not attach to the print bed. Vlasea et al used the powder-bed binder jetting process to produce silicone structures [21].…”

Volumetric Additive Manufacturing of Polymer Structures by Holographically Projected Light Fields

“…Paulsen and Chung later extended this technique by using inertial fluid shaping to add complexity in the third dimension [31], but still with significant geometric limitations. Kim et al used an approach they dubbed "low one-photon polymerization (LOPP)" [32] to polymerize simple structures in bulk resin. Gandhi and Bhole [33] modulated the depth of polymerization in a laser-scanned stereolithography process by adjusting the laser intensity and scan speed, resulting in non-planar structures.…”