The researchers explained that to accomplish such features in typically rigid hydrogel, they used ultra-thin clay nanosheets, which created a dense entangled network of polymers that strengthened hydrogels and prevented them from being too soft. This also, reportedly, increased the gel’s ability to self-repair.

Illustration of hydrogels in a mobius-ring formed through self-healing. Source: Margot Lepetit/Aalto University

The team noted that they mixed a powder of monomers with water containing the nanosheets and that mixture was subsequently placed under a UV lamp wherein the UV radiation from the lamp caused the individual molecules to bind together so that everything became an elastic solid, otherwise known as a gel.

As such, the team explained that the hydrogel’s healing process was expedited, reportedly repairing 80% to 90% of itself within the first four hours of being cut, and they restored themselves entirely after twenty-four hours. The team also noted that the hydrogel is comprised of 10,000 layers of nanosheets in a sample that is 1 mm thick, which enables it to achieve stiffness similar to that of human skin while also allowing it to stretch.

The study, “Silk-inspired in situ web spinning for situated robots,” appears in the journal Nature Materials.