Development of surface treatment technology for long-term retention of hydrophilic properties after plasma exposure

Abstract Hydrophilicity is essential for the reproducible and smooth passage of fluids through micro- and nanoscale microfluidic channels. Plasma exposure is a widely used method that can hydrophilize surfaces in a short time, with the additional advantage of being able to spread the interior of microfluidic channels. However, the hydrophilicity is rapidly lost when hydrophilization is achieved solely by plasma exposure. Therefore, an additional surface treatment technology that maintains long-term hydrophilicity is required. In this study, we compared hydrophilization of silicon nitride surfaces by surfactant coating and by plasma-induced polymerization.