Design, testing and optimization of a microfluidic device for capture and concentration of bacteria

Abstract

Effective detection of bacterial pathogens in large sample volumes is a challenging problem. Pre-concentration routines currently in practice before the actual detection process are cumbersome and hard to automate. An effort is made to address the problem of volume discrepancy between day-to-day samples and the concentrated samples needed for analysis. Principles of conceptual design are used in formulating the ‘Need Statement’, ‘Function Structure’ and in identifying the ‘Critical Design Parameters’ and ‘Design Constraints’. Electrokinetic phenomena are used to exploit the surface charges on bacteria. Electrophoresis is used to transport the bacteria to electrode surface and “Electrostatic trapping” is then used to capture these microbes on the electrode surface. The captured microbes can then be concentrated in a concentrator unit. A prototype microfluidic device is fabricated for showing the proof of concept. Optimization is done to minimize hydraulic power consumption and wetted volume. Observations from the initial prototype device along with the optimization results are used in building a new prototype device. Operation of this device is demonstrated by capture of bacteria from flow. Qualitative studies are conducted and preliminary quantification is also done.