Microfluidic Genetic Analysis with an Integrated a-Si:H Detector

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Abstract
We have developed an integrated hydrogenated amorphous silicon (a-Si:H) fluorescence detector for microfluidic genetic analysis. It consists of a half-ball lens, a ZnS/YF3 multilayer optical interference filter with a pinhole, and an annular a-Si:H PIN photodiode allowing the laser excitation to pass up through the central aperture in the photodiode and the filter. Microfluidic separations of multiplex PCR products generated from methicillin-resistant/sensitive Staphylococcus aureus (MRSA/MSSA) DNA on microfluidic capillary electrophoresis (CE) devices are successfully detected with the integrated detector. Similarly, multiplex PCR amplicons from the kanamycin resistant and K12 serotype-specific genes of E. coli cells are detected. The direct detection of multiplex PCR amplicons indicates that the fluorescence detector can be successfully coupled with current microfluidic PCR-CE platforms. This work establishes that the integrated a-Si:H detector provides relevant limits of detection for point-of-care genetic and pathogen analysis with microfluidic devices.