Microfluidic Platforms for Biological Investigations

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This research program will generate new knowledge on mechanics of liquids interactions with physical and biological specimens at microscale dimensions. Particularly, it seeks to explore the flow-induced focusing of rigid microparticles, flexible micro-objects, and flexible microdroplets inside liquids with various properties in microchannels. The gained fundamental knowledge supports collaborations to develop microfluidic devices and Lab-on-Chips for important health and safety applications, such as point-of-need food and water testing, field-based environmental and safety monitoring, neurodegenerative disease studies, and high-throughput drug screening. Use of rigid microparticles and methods to sort them are on the rise in biosensing, therapeutic, and drug delivery applications. We will investigate the effects of (a) fluid viscosity and density, (b) particle size and shape, and (c) channel design and size on particle focusing. We will work with synthetic two-phase fluids mimicking blood, complex water and beverages in curved channels similar to real-life scenarios like arteries and veins. Flexible particles are common in multiphase microfluidics, but their migration and focusing in non-straight channels is not well-understood. We will use small-scale embryos and larvae of established biological disease model organisms (worm, fruit fly) as realistic non-spherical flexible microparticle models. We will develop microdevices for measurement of their mechanical properties, while exploring the use of chemicals and electric signal to modulate their deformability. The effects of organisms' shape and flexibility on focusing in curved channels will be studied. Fundamental understanding of hydrodynamics of flexible biological objects with elliptical, cylindrical and rod-shaped geometries in microfluidics will be obtained. Multi-material droplets are ubiquitous in applications like food, cosmetics and pharmaceuticals, but their versatile production with precise micrometric size and material properties is yet to be achieved. We will fabricate a modular setup in which droplet generation units will be mounted onto precision-printed configurable fixtures. We will use the system to generate double-emulsion water-in-oil-in-water droplets with core-shell and drop-in-drop configurations. We will determine the effects of fluid properties, channel design and flow rate on droplet size, shell thickness and droplet configuration, and determine droplet generation regimes and configurations. Comprehensive guidelines for double-emulsion droplet generation will be provided. This program will train 10 undergraduate and 8 post-graduate students in 5yr. They will gain skills in experimental research including design and fabrication of microfluidic devices and applying them to solve engineering problems in the field of multi-phase microflows. Moreover, trainees will gain soft skills in dissemination of research findings via writing papers and giving talks at conferences.