A microfluidic device that comprises one or a plurality of microchannel structures each of which comprises a microconduit for transport and/or processing of liquid, the inner surface of which comprises a hydrophilic liquid contact surface area (surface area 1) that is delineated in at least one direction by a boundary to a hydrophobic surface area (surface area 2). The characteristic feature is that surface area 2 comprises a rough part that stretches along the boundary.