CAREER: Symmetry-based microfluidics and perturbation-free micromanipulations of swimming microorganisms

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Precise control of fluid flow in small geometries, or microfluidics, has been used as a powerful means of controlling or transporting small particles. Microfluidics can be potentially used to manipulate microorganisms to study how they sense the mechanical properties of their environment (mechanosensation). Gaining a full understanding of the mechanosensation of these microorganisms may lead to mechanical control of their behavior as an alternative to the traditional chemical treatments in ecological, environmental, and health applications. The advancement in microfabrication techniques has yielded increasingly sophisticated geometries in microfluidic devices, and the flow within these devices can be predicted using computational fluid dynamics. This project explores the fundamental principles that govern microfluidic flows relevant to micromanipulation of microorganisms, using a technique called symmetry-based abstraction. Advanced microfluidics and three-dimensional imaging techniques developed for this project can be directly transferable to many biological, medical, and industrial applications. The proposed endeavor also consists of notable educational components, including “Virtual Imaging Lab” and “Kirigami-Origami Microfluidics” outreach programs that bring interactive research experiences to both the regular classroom and virtually to the public.The goal of this project is to establish a symmetry-based framework of understanding and then modulating microscale flow patterns for advanced micromanipulations. This level of controlled microfluidic environment will be used for isolating the passive mechanical responses of microorganisms to surrounding media from active responses. This functionality will elevate our understanding of the mechanical effects and lead to mechanical treatments for biological controls. The approach is to (i) develop and experimentally measure a symmetry-based foundation of microfluidics for advanced manipulation functions, (ii) extend these capabilities to perturbation-free manipulations of living cells (by building a “bacterial treadmill”), and (iii) ultimately realize channel-free and pixelated microfluidic applications. By bridging flow patterns and flow symmetries, a broader design space of microfluidics beyond simple geometries is made available for advanced microfluidic applications. By robustly isolating the microorganisms from mechanical perturbations through flow symmetries, a controlled comparison of microorganisms under perturbation-free and mechanically perturbed conditions becomes viable. This comparison will quantitatively provide the mechanoresponses of microorganisms to surrounding media. This understanding also provides us a rigorous approach to explore the true hydrodynamic effects of swimming microorganisms.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.