CAREER: Harnessing viscous streaming in complex active systems: mini-bots in fluids

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Artificial and bio-hybrid (partly synthetic, partly biological) miniaturized swimming robots to navigate through the blood stream and deliver drugs have great potential in biomedicine. Viscous streaming is a phenomenon where an oscillating body generates stable, predictable and robust fluid flows that can be used to manipulate the body's local surroundings. Viscous streaming is being proposed for transport, mixing, and particle assembly, and it may be suitable for transport of mini-bots intended for applications in biomedicine. One limitation is that while streaming phenomena are well understood for simple bodies, little is known in the case of complex geometries. This proposal combines modeling and experiments to tackle the knowledge gap that relates viscous streaming to body shape. This knowledge will connect biology and robotics to enhance current capabilities of mini-bots and enables new ones. This research will pave the way to transformative applications such as localized drug delivery, precision manipulation, and fabrication. This is in line with the national need to increase medicine effectiveness as well as competitiveness in manufacturing via advanced computational methods. The proposed research has broad educational impact at the cross-section of fluid mechanics, simulations, robotics, and bioengineering. A set of outreach activities and intuitive learning modules will be designed to spark interest in fluid mechanics and engineering. A broad and diverse group of graduate and undergraduate students from different disciplines will be engaged. This proposed research delineates a roadmap to understand streaming beyond classic cases. The role of curvature, an aspect largely neglected, is dissected from a mathematical, dynamical and physical perspective via a conceptual framework that combines simulations, method of successive approximations, bifurcation and flow topology analysis, experiments. Then, (1) simple 2D and 3D shapes will be considered to investigate the effect of symmetry breaking, corners and variable curvature with respect to classical solutions; (2) most representative cases will be experimentally verified; (3) insights will be exploited in untethered synthetic and bio-hybrid mini-bots targeting biomedical applications. The outcome is a set of design principles captured by scaling relations, phase diagrams, and proof-of-concept demonstrations. This is complemented by methods, algorithms, software and data made publicly available to lower barrier entries, thus broadening the scope of this technology.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.