Monolithic integration of microfluidic channels and optical waveguides using a photodefinable epoxy

This work describes a novel use of a photodefinable epoxy to monolithically integrate low cost optical-microfluidic sensor devices. The chip consists of multimode waveguides, sealed microchannels and optical connectors on a silicon wafer. The process consists of (i) 4 successive photolithographic steps, (ii) a bonding process, (iii) and a final releasing step. The core of the waveguide is made of SU8 in a liquid aliphatic epoxy resin. Despite the dilution, the SU8:aliphatic epoxy is still able to be patterned by photolithography.