Electro-Actuation of a Smart Hydrogel Compatible With 3D Printing

Hydrogels that can change shape on the application of an electric field are receiving increasing attention due to their potential to fulfill a range of functions in biomedicine, including the controlled release of therapeutic agents or the creation of replacements for contractile tissues. In this manuscript, a novel electroactive polymer was reported based on the copolymerisation of 2-acrylamido-2-methylpronane sulfonic acid and poly(ethylene glycol) diacrylate (AMPS-co-PEGDA), via free radical polymerization using UV light. It was shown that to enable curing and the production of a material that could repeatably actuate without cracking, 900 mJ/cm² (at 365 nm^-1) of UV exposure was optimal. Further increasing the curing time resulted in the production of a brittle material that cracked following actuation, preventing multiple actuations from occurring. The polymer that was cured for 900 mJ/cm² was shown to be non-cytotoxic to dermal fibroblast cells, showing potential in biomedical applications. Furthermore, it was shown that the optimized polymer could be structured using a process of suspended 3D printing, allowing for the manufacture of complex, electro-actuatable geometries. Processing in an agarose supporting bed resulted in a reduction in the Young's modulus of the printed polymer and an associated greater degree of bending. These results demonstrate that the optimized (AMPS-co-PEGDA) polymer is a promising electroactive material with tuneable properties and complex geometries, suitable for advanced biomedical applications.