Rapid mold-free manufacturing of microfluidic devices with robust and spatially directed surface modifications

A new and easy-to-use method that allows for mold-free and rapid prototyping of microfluidic devices, comprising channels, access holes, and surface-modified patterns, is presented. The innovative method is based on direct photolithographic patterning of an off-stoichiometry thiol-ene (OSTE) polymer formulation, tailor-made for photolithography, which offers unprecedented spatial resolution and allows for efficient, robust and reliable, room temperature surface modification and glue-free, covalent room temperature bonding. This mold-free process does not require clean room equipment and therefore allows for rapid, i.e., less than one hour, design-fabricate-test cycles, using a material suited for larger-scale production. The excellent photolithographic properties of this new OSTE formulation allow patterning with unprecedented, for thiol-ene polymer systems, resolution in hundreds of micrometers thick layers, 200 μm thick in this work. Moreover, we demonstrated robust, covalent and spatially controlled modification of the microchannel surfaces with an initial contact angle of 76° by patterning hydrophobic/hydrophilic areas with contact angles of 102° and 43°, respectively.