Hydrogel Helps Soft Materials Keep Up In 3-D Printing Craze

Researchers at the University of Florida, Gainesville, have developed a hydrogel matrix that acts as a solid support system for objects made with three-dimensional printing, yet the gel is almost entirely liquid (Sci. Adv. 2015, DOI: 10.1126/sciadv.1500655).

The team, led by Tapomoy Bhattacharjee and Thomas E. Angelini, has printed a variety of soft materials—such as polymers and living cells—inside this hydrogel to create arbitrarily complex structures that keep their shape. The hydrogel bolsters the ability of 3-D printers to create soft, functional structures, potentially including living tissue.

The gel contains microscopic particles made from a copolymer of polyaspartic acid and polyethylene glycol. But the copolymer accounts for less than 1% of the weight of the matrix, Angelini says. The rest is mostly water.

A 3-D printer’s nozzle can slip through the hydrogel as if the material were a liquid, but the particles are large and substantial enough to hold any printed material in place. “It’s like it’s trapped in a liquid without being able to sink,” Angelini tells C&EN.

“This is a beautiful piece of work,” says Jennifer A. Lewis, who was not involved with the study and has also developed novel support materials for 3-D printing with her group at Harvard University. She says what differentiates this granular hydrogel is its ability to flow back into place once the print nozzle passes through it.

The growing soft matter engineering team at the University of Florida now includes researchers from across campus who are working to print accurate polymer brain models that surgeons can use for practice and living human tumors for cancer research, Angelini says.