A Continuous Microfluidic Concentrator for High-Sensitivity Detection of Bacteria in Water Sources

Water contamination is a critical issue that threatens global public health. To enable the rapid and precise monitoring of pathogen contamination in drinking water, a concentration technique for bacterial cells is required to address the limitations of current detection methods, including the culture method and polymerase chain reaction. Here we present a viscoelastic microfluidic device for the continuous concentration of bacterial cells. To validate the device performance for cell concentration, the flow characteristics of 2-μm particles were estimated in viscoelastic fluids at different concentrations and flow rates. Based on the particle flow distributions, the flow rate factor, which is defined as the ratio of the inlet flow rate to the outlet flow rate at the center outlet, was optimized to achieve highly concentrated bacterial cells by removal of the additional suspending medium. The flow characteristics of 0.5-, 0.7-, and 1.0-μm-diameter particles were evaluated to consider the effect of a wide spectrum of bacterial size distribution. Finally, the concentration factor of bacterial cells, Staphylococcus aureus, suspended in a 2000-ppm polyethylene oxide solution was found to be 20.6-fold at a flow rate of 20 μL/min and a flow rate factor of 40.