Optofluidic biosensors: miniaturized multi-color flow cytometer and fluorescence-activated cell sorter (microFACS)

We report a portable, low-cost, and high-performance microfluidics based fluorescence-activated cell sorter (microFACS) system to isolate E.coli. cells in combination with a modified specific fluorescence labeling method called tyramide signal amplification-fluorescence in situ hybridization (TSA-FISH). One of the primary challenges in studying bacterial communities that elude cell culturing is to isolate of low abundance bacteria cell from heterogeneous microbial samples. The proposed TSA-FISH protocol is flow cytometry compatible and yields about 10-fold enhancement in fluorescence labeling intensity over widely used standard FISH staining methods. Teflon AF coated optofluidic waveguide and space-time coding with a matched filter algorithm enhance its detection sensitivity. The microFACS is also able to enrich TSA-FISH labeled E.coli. cells by a factor of 223 with an integrated piezoelectric actuator and realtime control electronics system. The microFACS in conjunction with the modified TSA-FISH technologies demonstrates a highly effective and low cost solution potentially for the genomic complexity of complex bacterial communities.