Biological tissues have evolved over millennia to be optimised for their specific functions. For example, cartilage is a compliant elastic tissue that is soft enough to cushion joints but strong enough to resist compression and withstand substantial loads.

Creating synthetic replacements that match the properties and behaviour of biological tissues has not been easy, but scientists at the University of Colorado Denver (CU Denver) — led by mechanical engineer Chris Yakacki — have 3-D printed a complex porous lattice structure using liquid crystal elastomers (LCEs) to create devices that mimic cartilage and other biological tissues.

The CU Denver team plus scientists from the Southern University of Science and Technology in China reported their findings in the journal Advanced Materials. Professor Yakacki, who works at CU Denver’s Smart Materials and Biomechanics Lab, began working with LCEs in 2012.

For their latest study, he and his team explored a 3-D printing process called digital light processing.

They developed a honey-like LC resin that cures and forms new bonds in a succession of thin photopolymer layers when it is hit by ultraviolet light. The final cured resin forms a soft, strong and compliant elastomer; and when printed in lattice structures (levels of patterning akin to a honeycomb), it began to mimic cartilage.