When it comes to 3D printing, the sky is the limit. As 3D printing technology continues to advance, applications can be as far reaching as airplane and automobile parts to medical devices and even anatomically correct, biocompatible models. Although 3D printing technology is developing at a rapid pace, the technology itself is not new. It emerged in the 1980s as a means of creating rapid prototypes. In recent years the applications for 3D printed models have evolved with the available hardware, software, and printable materials. Evolving technology, paired with the creative and innovative minds of scientists, engineers, and physicians, has been the launching pad for developments within 3D printing technology specific to healthcare. One way 3D printing technology is poised to create better patient outcomes is in creating an anatomically and patient-specific models to aid in surgery and medical procedures. With the capability to 3D ...
Think of a flower growing. Biological tissues have always been able to change shape because cells swell and stretch. Now, polymer scientists and engineers have developed a polymer gel and lithography technique that can follow those kinds of transformations.
Rebecca Boyle reports for Popular Science:
For the first time, engineers have figured out how to induce this action in sheets of synthetic gel, creating self-curling and folding structures that can contort on command.The new method, called halftone gel lithography, could someday be used in anything from soft robots to tissue engineering, researchers say. It’s like a new method of 3-D printing — call it 3-D curling.
Basically, the polymer gel swells when it is exposed to water. But it won’t swell where the “resist dots” are added to the polymer gel with the lithography process. Making same-size dots in a uniform pattern will make the sheet swell but stay flat when exposed to water. Creating different-size dots in different areas yields a 3-D shape, as shown in the video above and reported in the journal Science. The researchers crafted various shapes, including spheres, cones, and saddles.
Boyle describes how the researchers did it:
Ryan Hayward, Christian Santangelo and colleagues at the University of Massachusetts Amherst worked with ultrathin sheets of an elastic polymer that shrinks when it’s heated. They spread a 10-micrometer-thick layer of polymer onto a substrate, and exposed patches of it to ultraviolet light. The light-exposed portions become crosslinked polymer chains, while areas that were masked will swell and expand when they’re exposed to water. This selective swelling causes the whole sheet to warp and buckle, mimicking the concept of cellular swelling that drives the growth of soft tissues. To start again, just dry out the sheet.
David Bradley provides more details about the polymer chemistry in Chemistry World:
The team focused on poly(N-isopropylacrylamide) copolymers containing pendant benzophenone units. The benzophenone groups allow cross-links to be formed between polymer chains that are readily tuned by the dose of incident ultraviolet irradiation. By using two photo-masks to create patterns of dots, the team was then able to control the pattern of irradiation on a thin layer of this polymer. […] The process is akin to printing a halftone image in a newspaper where the patterns of ink dots produce an image that looks smooth and realistic to the naked eye.
Paul Topham of Aston University in the U.K. told Chemistry World that “the work is truly ground-breaking.”
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