Dispersion in Microfluidic Suspensions: Experiments and Numerical Simulations

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1133106PI: MaxeyDispersion of microspheres and cells has become a critical issue in a number of biological and microfluidic applications. While it is well known that pressure driven flows through a microchannel leads to ?Taylor dispersion? of solute plugs, the dispersion characteristics of particulate or biological cell suspension plugs have not been explored in detail. The dispersion is observed on time scales such that the particles sample many streamlines due to microchannel wall and multiparticle hydrodynamic interactions. In most of the above microfluidic applications, single or multiple dilutions of reagents are required in order to perform reactions or measurements over a range of concentrations using only one set of sample solutions to fill the inlets. It is often unclear how to design the dilution channel or channels for achieving minimum dispersion of the plugs. New insights on particle fluxes and mixing in microchannel flows are needed to develop models for concentration fronts or strongly inhomogeneous flows as opposed to fully populated flows. The proposed research and education program launches a fundamental approach to analyze dispersion in microfluidic suspension flow of microspheres and biological cells. The research program will develop a new experimental platform for performing benchmark suspension plug transport experiments using different kinds of solid and soft particles. The program will also develop a new, fully resolved, numerical simulation framework for exploring isolated suspension plugs that are inherently inhomogeneous and may vary rapidly over short distances. These studies will impact our fundamental understanding of transport in microscale systems, and will lead to technological advances in diverse areas relevant to micro-reactor design and two-phase flows with applications to high throughput screening and bio-separations. The project will develop a crucial understanding of transport of suspension and cellular plugs under different length and time scales. This will accelerate the exploration of new systems for performing rapid screening with high efficiency to detect and analyze minuscule samples. The project will also provide valuable training for new graduate research assistants in developing and applying the new research techniques. The work is at the interface of microfluidic device technology and scientific computing for a fundamental class of suspension flows, and will provide cross-disciplinary experience. There will be a coordinated outreach program involving undergraduate research projects and incorporating new material for interdisciplinary courses to train undergraduates from biology, physics, engineering and applied mathematics in new approaches. The PIs will participate in and contribute to Brown University?s Research Experience for Teachers Program (RET).