A novel concept of the integrated fluorescence detection system and its application in a lab-on-a-chip microdevice

In the paper, an innovative concept of fabrication of lab-on-a-chip (LOC) analytical microsystems, is presented. One of the major trends in design and fabrication of the LOC devices is integration of microfluidic separation part of the device with its detection optics. In our paper, we report a novel approach to this problem. As a substrate material for our LOC device, we choose soda lime glass plates in which we prepare channel optical waveguides, with the use of an ion exchange technique. Then, the microfluidic system is fabricated in the same substrate utilising standard photolithography and wet etching methods. As a result, we obtain a truly integrated, monolithic microsystem, containing both microchannels and microoptics, fabricated in the same substrate. The waveguiding optics is used to excite the fluorescence in the microchannels, while for the fluorescent beam collection, various approaches are tested: waveguide, free space and fibre optics. The quantitative results of the fluorescence experiments are also presented, namely calibration curves and level of detection values. Finally, an exemplary application of the system is demonstrated for the separation and detection of the mixture of Cy3 fluorescent dye and Cy3 tagged streptavidine.