Automated sample processing for flow cytometry

The utility of pathogen and toxin detection systems depends not only upon sensitivity, specificity and capability for multiplexed recognition, but also on access at the point of need, ease of use, and response time. Combining microfluidics and optical biosensors facilitates miniaturization and automation, while careful design makes it possible to test variable quantities of complex matrices such as food (mL) and clinical samples (µL). We report on progress towards an optofluidic system that combines a rotating magnet trap for automated sample processing and a microflow cytometer capable of 4-color analysis to achieve multi-analyte diagnostics. Sample and antibody-coated magnetic beads are introduced into a moving magnetic field created by magnets rotating in the opposite direction of the flow. The color-coded magnetic beads with captured target remain in suspension while fluorescent tracer reagents are introduced to the flow, thus optimizing the binding kinetics and minimizing aggregation. Magnetic beads with bound target and tracer reagents are released for multiplexed analysis by reversing the direction of spinning magnets.