Swellable Plasma Polymer Films for Use in Hydrogel-Based Biomedical Devices

Swellable plasma polymer films have been deposited on silicon wafers and hydrogels in a low-pressure PECVD system. Deposition characteristics and physico-chemical characterization data of swellable oxygen-rich plasma polymerised ethylene films were studied. These films were deposited using gas flows consisting of C₂H₄ (5 sccm) and CO₂ (10–40 sccm). Using profilometry, changes in thickness of films over multiple water immersion and drying cycles were recorded. Changes in the structure and morphology of films was also evaluated by using scanning electron microscopy, dye permeation studies and atomic force microscopy. Mechanical properties of the films were studied by using nanoindentation experiments, and intrinsic residual stresses were also calculated for the films. The behaviour of films was dependent on the flexibility and water content of the underlying hydrogel substrates. These findings pave way for creation of stable plasma polymer films on biomedical devices made from hydrogels.