NSF-BSF: Modeling and Control of Collective Dynamics for Externally Driven Planar Microswimmers

This grant will fund research that enables innovative uses of microrobotic devices in a variety of healthcare applications, including non-invasive surgery, drug delivery, and treatment of infection and infertility, thereby promoting the progress of science and advancing the national prosperity and health. Deployment of such microrobotic devices requires an understanding of principles of microscale propulsion, for example swimming of microorganisms in various fluidic environments, and the development of methodologies to control propulsion.

This project aims to address a current gap in our knowledge of how to achieve controlled propulsion of single planar robotic microswimmers and groups of such swimmers in real fluids of biomedical relevance, including saline, methylcellulose, and synthetic mucus. The theoretical and experimental work conducted in this project brings together fluid mechanics, small-scale fabrication, and control theory.

The project will benefit from a unique international collaboration between researchers in the US and Israel. Educational activities centered on microswimmers, as well as their propulsion and control, will be integrated in instruction and outreach, helping to broaden participation in STEM from currently underrepresented groups.

This research aims to make fundamental contributions to the optimal design and control of robotic microswimmers for low-Reynolds-number propulsion in both Newtonian and non-Newtonian fluidic environments, including biomimetic tissue-like materials. It achieves this outcome by investigating planar microstructures that can be fabricated in bulk using standard photolithography, and exploring different gaits realized through variations in geometry, surface functionalization, and external actuation using laser excitation, chemical catalysis, thermal gradients, and magnetic fields.

The research will result in the development of a stochastic differential-equation-based model of planar propeller behavior in response to environmental disturbances, as well as the design of a feedback control algorithm that anticipates uncertainty while tracking stochastic moving targets or realizing optimal path-planning and navigation in the presence of stochastic drifts. The work will contribute to a practical understanding of maneuverability and path planning of microswimmers in complex fluidic environments, both individually and in swarms.

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.