Integration of microfluidic and microoptical elements using a single-mask photolithographic step

We present a design and process to fabricate an integrated microfluidic/microoptical device-the microfluidic optical waveguide sensor ("muFlOWs"). Optical waveguides and fluidic microchannels have been defined using only a single photolithographic masking step. This integration has been demonstrated with three device types: (A) a hybrid structure with embedded SU-8 waveguides and polydimethylsiloxane (PDMS) channels; (B) a structure using only SU-8 for both the waveguides and microchannel walls and (C) a structure as a modification to the all-SU-8 structure. Testing has demonstrated the ability of the waveguides to transmit light to and receive light from the microchannels, which contain a fluorescent dye that en-tits upon laser excitation. This type of strategy can find effective use in a variety of bio-assay experiments. (C) 2004 Elsevier B.V. All rights reserved.