To make a shrinking, color changing Arc de Triomphe, the Ke Group uses a Direct Ink Writing method of 3D printing. Like FDM/FFF based techniques, an object is built up through the extrusion of successive layers, the main difference is the feedstock, and resulting operating temperature.
In the proof of concept experiment, a benchmark model of the Arc was FDM/FFF 3D printed in ABS and a second Arc, matching the scale of the ABS benchmark, was 3D printed in the lab’s specially developed G1 hydrogel ink.
As visible from the picture below, Direct Ink Writing produces a rough, yet discernible, structure of the Arc, at 300-micron resolution.
After air drying, and calcination (At a temperature of 700°C) the G1 Arc shrinks to 1 percent of its original size, with 10 times the resolution.
While rudimentary, the technique represents a step-changing possibility that could bring down the cost of industrial 3D printers. “This process can use a $1,000 printer to print what used to require a $100,000 printer,” explains Ke, adding that the “technique is scalable, widely adaptable and can dramatically reduce costs.”
In addition to shrinkage, models made using the G1 hydrogel ink can be tuned to change color by adding fluorescent markers to the ink. The chameleon-like change is activated by shining a light on the surface.
“This is something we’ve never seen before,” adds Ke, “Not only can we 3D print objects, we can tell the molecules in those objects to rearrange themselves at a level that is viewable by the naked eye after printing,”
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