This document describes a conformable substrate that includes a hydrogel having adhesion-promoting moieties, said adhesion-promoting moieties comprising one or more catechol groups. The conformable substrate includes an array of microelectrodes bonded to the hydrogel by the adhesion-promoting moieties via the one or more catechol groups. This document also describes a method for transfer printing of an electronic structure to a hydrogel. The method includes the steps of coating a donor substrate with a film of polyacrylic acid, crosslinking the film of polyacrylic acid in a solution comprising divalent ions, patterning a microelectrode array onto the crosslinked film of polyacrylic acid, laminating an adhesive hydrogel substrate onto the donor substrate coated by the crosslinked film of polyacrylic acid comprising the patterned microelectrode array, and separating the crosslinked film of polyacrylic acid from the donor substrate in a monovalent solution.
