As it wends the material into delicate hair-thin veins, this new 3D printer is doing two amazing things. First, unbound by the constraints of gravity, it is pumping a suspended 'painting' into a buoyant gel the consistency of hand-sanitizer. And second, the material you see being injected here is living, human cells.

Today, a team of engineers and biomedical researchers led by Tapomoy Bhattacharjee and Thomas Angelini at the University of Florida has unveiled a radical new 3D printing technology. It's a machine that takes advantage of the curious properties of granular gels—seemingly sci-fi materials that act like they're stuck halfway between liquid and solid states. According to the paper they just published in the journal Science Advances, the researchers have already shown that the machine can paint in soft materials such as silicone and hydrogels—which otherwise flop flat and deform during the 3D printing process—with incredibly fine and elegant detail.

Over the past year, the team has used the machine to paint an unbounded number of shapes with seven different types of living cells, including primary cells grown from a patient, and various soft materials. For example, the scientists produced silicone jellyfish and suspended networks of veins written entirely out of living human aortic cells. Better still, their machine can print at a resolution of roughly 1 micron. That's 1 percent the width of a human hair. The scientists see their new 3D printer being used in building flexible electronics and even making an earnest foray into organ and tissue engineering.

"You could personally replicate and print that person's brain with a soft material."

"This is a beautiful piece of work. . . the basic concept of the embedded 3D printing is quite powerful," says Jennifer Lewis, a leading 3D printing expert and engineer at Harvard University who was not involved in the development of the new device. "The surrounding [material] provides support and allows one to pattern truly free-form architectures."

Strange Gel

According to Angelini, the concept of embedded 3D printing, where a material is printed into a liquid or solid substance, is something researchers have trying for years. The benefits are manifold: "It changes the way you think about 3D printing," Angelini says. "It goes from being about melting certain materials and limiting yourself to structures that can't collapse while being printed to just placing those objects in 3D space wherever you want. And so long as you can push a material out of a needle—and have it be trapped by the [embedding medium]—there's no limit to what you could print with."

But previous attempts at embedded 3D printing hit a seemingly unscalable wall. What the heck are are you supposed to print into? Print into a liquid and you'll invariably end up with a chaotic mess, as your constantly moving injector needle will stir your painting into a whirlpool. Print into a soft solid and watch as the needle churns everything into the consistency of chunky, mushed-up Jello.

Angelini's solution? Use a material that acts like a liquid and solid.

The team's new 3D printer prints into a odd and only recently understood substance called granular gel. When immobile, granular gel acts pretty much just like a solid: It'll hold the printed matter in place. But when the 3D printer's needle moves through the gel, the material semi-liquifies in the immediate vicinity around the needle—but no farther. This allows the needle to move smoothly without disrupting the rest of the gel or the delicate print.

"So long as you can push a material out of a needle, there's no limit to what you could print with."

The strangeness of granular gel goes down to the molecular level, says Angelini. The round, bundle-like molecules that make up the gel are big and sticky enough to refuse the random motion that causes other liquids to move about chaotically (this is called brownian motion). But they're not so sticky that, like solids, they resist more forceful movements like the push of a needle.

When the scientists are finished printing, the granular gel can be gently washed away with water, leaving the printed material in exactly the three-dimensional design they wanted. Angelini says the gel does have one major limitation: Really tiny molecules can slip past the individual grains of the gel. But most of the materials Angelini's team is interested in working with (from cells to long-chain polymers) are more than big enough for this to work.

Biomedical Bounty

In multiple videos released alongside their paper, Angelini and his colleagues have already shown that using their new printer to create objects with various mixes of soft materials—from jellyfish to nesting Russian dolls—is a breeze. But Angelini sees more astounding commercial uses for the printer, especially in the biomedical realm.

For one thing, Angelini has recently shown that cells can not only survive in the granular gel, but can even grow in it. That's because the same size limitation that causes small molecules to slip through the gel can be used to deliver all the necessary nutrients to cells. Angelini foresees a future in which cancer researchers will be able to study thousands of spherical malignant cancer tumors, all carefully placed and nurtured within a single cube of granular gel rather than inside thousands of mice. As for tissue engineering, the researchers are already tinkering. In one experiment, the scientists successfully grew flat layers of injected canine liver cells on top of injected collagen.

And there's another even more curious application to the new 3D printing breakthrough: helping brain surgeons practice their craft. Here's how it'd work: You'd take an MRI or CTI scan of a brain tumor and surrounding brain region, Angelini says, "and you could personally replicate and print that person's brain with a [soft material]." A surgeon could then practice on prints of the material until he or she gets it right

"Can you imagine?" Angelini says. "Hearing your surgeon say, 'Good morning, I've practiced this surgery on your brain five times already. You're in good hands.'"

This content is created and maintained by a third party, and imported onto this page to help users provide their email addresses. You may be able to find more information about this and similar content at piano.io