Design of a multi-stage microfluidics system for high-speed flow cytometry and closed system cell sorting for cytomics

To produce a large increase in total throughput, a multi-stage microfluidics system (US Patent pending) is being developed for flow cytometry and closed system cell sorting. The multi-stage system provides for sorting and re-sorting of cohorts of cells beginning with multiple cells per sorting unit in the initial stages of the microfluidic device and achieving single cell sorting at subsequent stages. This design theoretically promises increases of 2- or 3-orders of magnitude in total cell throughput needed for cytomics applications involving gene chip or proteomics analyses of sorted cell subpopulations. Briefly, silicon wafers and CAD software were used with SU-8 soft photolithography techniques and used as a mold to create Y-shaped, multi-stage microfluidic PDMS chips. PDMS microfluidic chips were fabricated and tested using fluorescent microspheres driven through the chip by a microprocessor- controlled syringe drive and excited on an inverted Nikon fluorescence microscope. Inter-particle spacings were measured and used as experimental data for queuing theory models of multi-stage system performance. A miniaturized electronics system is being developed for a small portable instrument. A variety of LED light sources, waveguides, and APD detectors are being tested to find optimal combinations for creating an LED-APD configuration at the entry points of the Y-junctions for the multi-stage optical PDMS microfluidic chips. The LEDs, APDs, and PDMS chips are being combined into an inexpensive, small portable, closed system sorter suitable for operation inside a standard biohazard hood for both sterility and closed system cell sorting as an alternative to large, expensive, and conventional droplet-based cell sorters.