The PAM/LiCl precursor solution was prepared as previously described. A shell mold with a geometry matching the base substrate but approximately 10% larger was employed. The precursor solution was poured into the shell mold, and the base substrate was placed inside, allowing the solution to fill the gap between the mold and the substrate. UV light was applied to the gap to initiate and complete crosslinking. Once crosslinking was achieved, the shell mold was carefully removed, leaving the crosslinked PAM/LiCl hydrogel layer adhered to the base substrate due to its strong adhesive properties.