Video: 3D-printing needle creates intricate objects in soft gels

To improve 3D printing, simply add gel. A fresh technique uses one to support complex shapes that would fall apart under their own weight in normal 3D printing.

This new-found combination of strength and delicacy will be crucial if we’re ever to print the biological structures that make up organs, blood vessels and other tissue.

The gel, which has the consistency of hand sanitiser, is made of an acrylic acid polymer. It works like a scaffold, allowing the printing of intricate patterns that would collapse without its support – such as nested Russian-doll-like structures and thin, complex branching networks.


This complexity is important. Researchers have long wanted to 3D-print whole human organs, but these need fine, dividing systems of blood vessels to supply them with oxygen and nutrients. The new technique enables printing at the right dimensions to do this, creating structurally sound spheres as thin as two sheets of paper and strands about 10 times thinner by embedding the objects in gel.

A hitch in using traditional 3D printing to create the kinds of structure found in our organs is that they collapse long before being finished. Printing into supportive gel gets around that challenge, preventing the creations from sagging or buckling before they solidify. The gel is supportive because it is essentially a solid, says Thomas Angelini at the University of Florida in Gainesville, who led the research.

Print for your life

Angelini’s team has already used the technique to print material out of living cells – including human blood-vessel and canine kidney cells. The researchers can also use silicone, hydrogel and other polymers, and made a replica of a colleague’s brain in the soft, tissue-like consistency of hydrogel to test it out. Internal organs are as individual as faces, so they based the brain on detailed images of the professor’s grey matter.

“We could foresee a future in which, before brain surgery, the surgeon 3D prints a brain out of hydrogel and then practises on it,” says Angelini. “Then the surgeon knows exactly how that surgery is going to happen.”

“They’ve made, I think, a significant advance,” says Jennifer Lewis of Harvard. “It’s a beautiful piece of work.” One of the limitations, she says, is that so far the gel is not organic, so it couldn’t keep 3D-printed tissue alive.

Neither can the gel be used for structures printed below a certain size because very small particles then slip out of it like fish through a net.

The use of 3D printing to make working tissue and organs is still a long way off, but Angelini is optimistic. “Our method, I think, represents a path towards that,” he says. “I really think we are going to get there.”

Journal reference: Science Advances, DOI: 10.1126/sciadv.1500655