Microfabricated Plastic Capillary Systems with Photo-definable Hydrophilic and Hydrophobic Regions

In this paper we present a monolithic fabrication process for microcapillary sys tems that permits the formation of stable, photo-definable hydrophobic ( ) and hydrophilic ( ) regions on plastic channels. Using this process we have demonstrated a simple injector that uses a hydrophobic patch for cutting and transporting sample drops. Hydrophobic regions are formed by coating the inner walls with a thin parylene layer, while the hydrophilic regions are formed by selectively etching away the parylene layer followed by evaporating a thin hydrophilic silicon dioxide layer.