Ink Technology Toughens Synthetic Hydrogels

A new study describes a three-dimensional (3D) printing technique used to print tough, fiber-reinforced hydrogels that mimic the strength and suppleness of human cartilage.

Researchers at the University of Wollongong (UOW; Australia) have developed an additive manufacturing process that combines digital modeling and 3D printing to prepare fiber reinforced hydrogels in a single-step process. The system works by simultaneously printing with two inks on a 3D printer customized with an ultraviolet (UV) curing system. One ink cures into a soft and wet hydrogel and the other to a hard and stiff plastic, which forms the reinforcing “fibers” within the structure.


The selective pattering uses a combination of alginate/acrylamide gel precursor solution and an epoxy based UV-curable adhesive (Emax) with an extrusion printer. Spatial control of the fiber distribution within the digital models allows for a spectrum of swelling behavior and mechanical properties with physical characteristics, ranging from “soft and wet” to “hard and dry”. A prototype meniscus cartilage was prepared to illustrate the potential application in bioengineering. The study describing the new technology was published on September 8, 2014, in ACS Applied Materials & Interfaces.

“Using computer aided design software, I can make a digital model of the fibers and hydrogel matrix, tuning the mechanical properties by carefully controlling the distribution of the fibers within our structures,” said lead author Shannon Bakarich, MSc, a PhD candidate at the UOW Intelligent Polymer Research Institute. “The printed fibers give strength to the hydrogel in the same way fiberglass gives strength to a surfboard.”

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