Figure 13. Strategies used to coat thin, robust hydrogel layers onto commercially available catheters.

(a) Schematic of hydrogel skin fabrication steps. Polymer-based substrates are first exposed to an organic hydrophobic initiator solution before undergoing immersion into an aqueous solution containing hydrogel monomers and hydrophilic initiators. Following curing and washing steps, thin and uniform hydrogel skins are developed on the polymer substrate via the surface-bound formation of hydrogel-polymer interpenetrating networks. (b) Images demonstrating the application of hydrogel skins onto medical devices. (c) Schematic of fabrication procedure implemented to produce conformal and lubricating hydrogel coatings on a catheter surface. (d) Images of a catheter and inflated balloon tip coated with hydrogel via fabrication using SGS. (a-b) Adapted with permission.^[175] Copyright 2018 WILEY-VCH. (c-d) Adapted with permission.^[181] Copyright 2019, American Chemical Society.