Correction to: Nature Biomedical Engineering https://doi.org/10.1038/s41551-020-0566-1, published online 29 June 2020.

In the version of this Article originally published, in the sentence beginning “Fibrin hydrogels were prepared by...”, the thrombin concentration of “50 U ml−1” was incorrect and should have been ‘1.25 or 2.5 U ml −1’, and in the sentence beginning “Gel slices were incubated in...”, “4 mM HCl” should have been ‘100 mM HCl’. All versions of the Article have been amended.