Nov 3, 2015 | By Kira

Just last week we heard about a novel 3D printing technique for creating brushable human-like hair, and now, a team of bioengineers from UCLA has developed a 3D printing method that allows for the production of complex micro-scale objects that are actually smaller than the width of a human hair. Titled Optical Transient Liquid Modeling, the technique relies on patterned ultraviolet light, fluid photopolymer material, and custom software, and has promising uses in various biomedical and industrial applications.

A 3-D printed microparticle about 500 micrometers in length.

While traditional 3D printing methods can create incredibly complex shapes and structures, doing so on such a small scale (less than a millimeter) has never been possible in the past because the ‘drops’ of liquefied material extruded by the 3D printer are simply too big. Using a series of microfluidic and optical technologies, however, the UCLA bioengineers were able to produce objects that measure between 100-500 micrometers, with features as small as 10-15 micrometers.

In the paper published in Advanced Materials, authors Chueh-Yu Wu, Keegan Owsley and Dino Di Carlo of the UCLA Henry Samueli School of Engineering and Applied Science describe their technique as “a novel fabrication method…in which a 2D light pattern exposes a photopolymer precursor stream shaped along the flow axis by software-aided inertial flow engineering.” Essentially, two different types of fluids—a liquid polymer that acts as the precursor material, and a liquid mold for the polymer stream—are combined in a series of tiny pillars. The arrangement of the pillars determines how the two flows mix and intertwine.

Next, the researchers used CAD uFlow software (available as a free download) to predict what shape altering the pillars’ location and sequence would produce. By stopping the flow of materials suddenly, they could use an ultraviolet light to ‘slice’ into the precursor stream in a predefined pattern. This means the object is shaped first by the stream, then again by UV light. “It’s like we squeeze dough through a mold, which is the liquid mold, to make a noodle and then cut the noodle into pieces using another mold — the patterned UV light,” explained lead author Chueh-Yu Jerry Wu.

A computer-aided design (CAD) tool for the rational design of inertial flows

“We know that shape often determines material function, so while we have a few ideas of what this could lead to, this fundamental capability to produce made-to-order 3D microparticles could be applied in ways we have not contemplated,” said Di Carlo, the principal investigator on the research and a professor of bioengineering at UCLA. “There are so many potential applications — in that sense, it’s really exciting.”

Some of the suggested applications include custom biomaterials that self-assemble to help tissue regenerate, or new industrial coatings or paints with unique light-reactive properties, however there are sure to be many other applications once they have developed the technique further. The researchers also confirmed that so far, they have used the technique to produce objects composed of organic materials (for biomedical applications) as well as particles whose movements can be precisely controlled by magnetism (for industrial uses).

Both the software and a similar technique involving microfluidic and optical technologies were previously developed by Di Carlo’s Microfluidic Biotechnology research group, whose purpose is to exploit “unique physics, micro environmental control, and the potential for automation associated with miniaturized systems for applications in basic biology, medical diagnostics, and cellular engineering.”

The research paper is titled “Rapid Software-Based Design and Optical Transient Liquid Molding of Microparticles,” and was partially supported by the National Science Foundation.



Posted in 3D Printing Application



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