Plasma surface treatment of polyethylene terephthalate films for bacterial repellence

An investigation of the effect of PET surface treatment in He/O2 rf discharges on the bacterial (Staphylococcus epidermidis) adhesion was performed. The study was carried out in constant discharge power conditions that allowed the isolation of the effect of gas pressure and bias potential. The increase of pressure and substrate bias was found to enhance the production of active species and ions in the discharge as well as the PET etch rate. Additionally, the surface roughness of all the plasma treated films, relative to the untreated PET, was higher at these conditions. However, no simple relation was found between bacterial adhesion and surface roughness. Plasma treatment is shown to significantly reduce bacterial adhesion to these surfaces and this is most probably associated with changes on the surface chemical structure and the surface energy.