From artificial cartilage to skincare products and soft armor, hydrogels are one of the most widely-used materials. Graduate student Michelle (Jing) Wang and advisor Dr. Justin Burton discovered something surprising: when mechanically sheared, stiff hydrogels exclusively dilate. This unexpected behavior stems from hydrogels’ ability to withstand large deformations, and may explain how biological tissues such as cartilage remain lubricated by imbibing fluid. Their results were recently published in Physical Review Letters: https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.134.148203.