Jan.24, 2014

The solvent-cast 3D printing technology is a highly versatile microfabrication technique that can be used to fabricate 3D geometries at room temperature. It was developed to produce various geometries such as straight filaments, towers, layer-by-layer scaffolds, and freeform circular spirals by the robotic deposition of a polymer solution ink onto a moving stage.

The research work, by Shuang-Zhuang Guo, under the supervision of professors Daniel Therriault and Marie-Claude Heuzey at École Polytechnique de Montréal, Canada, makes the cover of the prestigious journal Small.

Under applied pressure, an ink material which undergoes capillary shear flow inside the micronozzle, relaxes its stresses upon exiting the nozzle. The ink material is a fast-drying thermoplastic solution composed of dichloromethane (DCM) and ~30wt% of polylactic acid (PLA). As the solvent evaporates post extrusion, the diameter of the filament decreases and its rigidity gradually increases with time due to a locally higher polymer concentration.

Scheme 1. Schematic representation of the SC 3D printing process with a thermoplastic solution. a) Deposition of the polymer solution through a micronozzle. b) Rapid solvent evaporation post extrusion. c) Example of a 3D square spiral fabricated by the SC 3D printing technique.

This rigidity gradient enables the creation of self-supporting curved shape by changing the moving path of the extrusion nozzle, in which the filament bending occurs in the low rigidity zone of the newly extruded material. After most of the solvent evaporation, the rigidity of the extruded filament changes from fluid-like to solid-like, which facilitates the shape retention of the deposited self-supporting features. For successful printing of 3D freeform structures, the viscoelastic properties of the polymer solution and the solvent evaporation rate have to be set to ensure proper ink rheological behavior while providing a fast solvent evaporation. This 3D printing process enables the creation of different multifunctional microsystems featuring complex geometries.

Reseachers demonstrated three 3D printed microsystems featuring mechanical, microfluidic and electrical functionalities, such as a high-toughness microstructured fibre, a 3D microchannel and a Ka band antenna.

To make the antenna, the PLA helices were coated by a ~50μm copper layer using sputtering and an electrolytic bath. This manufacturing approach shows high potential to rapidly and cheaply build high-frequency compact antennas which could lead to new opportunities for modern satellites, ground and mobile communication stations.

These capabilities can be extended through the utilization of other thermoplastic-based inks and the printing of features at the submicrometer- and potentially nanoscale.

Watch below three examples of Solvent-cast 3D printing:

Solvent-cast direct-write printing of a microstructured fiber

PLA concentration: 26 wt%
Nozzle diameter: 30 μm
Robot velocity: 2.0 mm/s


Solvent-cast direct-write fabrication of a micro-cup

nozzle: 0.1 mm


Solvent-cast direct-write fabrication of a scaffold

nozzle diameter: 0.1 mm
Space between two adjacent filaments: 0.5 mm
Scaffold layer: 4


Solvent-cast direct-write fabrication of a circular spiral v4

Nozzle diameter: 0.1 mm
Spiral diameter: 0.6 mm
Pitch: 0.5 mm

Posted in 3D Printing Technology



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rambo wrote at 1/27/2014 3:29:01 PM:

Looks like a solid doodle.

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