Capillary molding is a second technique where a patterned PDMS is used as a mold. The patterns of the PDMS layer must first be brought into contact with a substrate (e.g. a glass slide). Capillary molding is then intended to fill the patterns of the PDMS mold with a liquid polymer. As the name of the technique implies, capillarity is exploited to progressively fill the patterns. As an alternative, suction can be used. After having cured the polymer, the PDMS can be gently removed, leaving solid microstructures at the surface of the substrate.