Particle Focusing in Staged Inertial Microfluidic Devices for Flow Cytometry

摘要

Microfluidic inertial focusing has been demonstrated tonbe an effective method for passively positioning micro-nparticles and cells without the assistance of sheath fluid.nBecause inertial focusing produces well-defined lateralnequilibrium particle positions in addition to highly regu-nlated interparticle spacing, its value in flow cytometry hasnbeen suggested. Particle focusing occurs in straight chan-nnels and can be manipulated through cross sectionalnchannel geometry by the introduction of curvature. Here,nwe present a staged channel design consisting of bothncurved and straight sections that combine to order par-nticles into a single streamline with longitudinal spacing.nWe have evaluated the performance of these stagedninertial focusing channels using standard flow cytometrynmethods that make use of calibration microspheres. Ournanalysis has determined the measurement precision andnresolution, as a function of flow velocity and particlenconcentration that is provided by these channels. Thesendevices were found to operate with increasing effective-nness at higher flow rates and particle concentrations,nwithin the examined ranges, which is ideal for highnthroughput analysis. Further, the prototype flow cytometernequipped with an inertial focusing microchannel matchednthe resolution provided by a commercial hydrodynamicnfocusing flow cytometer. Most notably, our analysis indi-ncates that the inertial focusing channels virtually elimi-nnated particle coincidence at the analysis point. Thesenproperties suggest a potentially significant role for inertialnfocusing in the development of inexpensive flow cytom-netry-based diagnostics and in applications requiring thenanalysis of high particle concentrations.