Coupling Confocal Fluorescence Microscopy and Microfluidic Device for Single Molecule Detection

The ability to accurately measure the mobility of particles at low concentrations in small volumes is very useful for a broad range of applications. The coupling of micro- and nano-fluidic devices and confocal microscopy offers an efficient and rapid technique for multiplexed single molecule detection and analysis. Microfluidic channels at micron and sub-micron scales were designed and fabricated on fused silica wafers. Fluorescence correlation spectroscopy and fluorescence lifetime were applied to measure and analyze the mobility of fluorescent species in micro-droplets, micro-channels, and nano-channels. The experimental results show a strong dependence on geometric configurations. Artifacts in the experiments are investigated and discussed.