Research Projects

Microswimmers are micron-sized biological or artificial entities, including motile cells and functionalized particles, that use internal or external energy to move autonomously in fluids. Inspired by motile cells such as bacteria, algae, protozoa, and sperm, artificial microswimmers have been developed that often achieve self-propulsion through asymmetric catalytic reactions on their surfaces. In recent years, they have garnered significant attention in microfluidics and active matter research because of their potential applications in targeted drug delivery, minimally invasive surgery, assisted fertilization, and lab-on-a-chip technologies. However, realizing these applications in practice remains challenging. A major difficulty lies in manipulating microswimmer trajectories in biofluids, especially under confined conditions relevant to microfluidic and in vivo environments. Microswimmers intended for biomedical use must navigate through biofluids such as mucus, blood, cytoplasm, and other bodily fluids. These fluids are inherently heterogeneous and crowded liquid media, often consisting of entangled polymer networks, macromolecules, colloids, and other microscopic components. Such fluid environments frequently exhibit viscous heterogeneity and non-Newtonian rheology, including shear-thinning viscosity, viscoelasticity, and anisotropy. Although swimmer behavior in unbounded, quiescent biofluids is relatively well understood, their motion in more realistic biofluid environments involving external flows and confinement remains poorly characterized due to the complex properties of these fluids. An outstanding question in this domain is whether controlled motion of microswimmers can be achieved in confined biofluid environments under imposed flow conditions. To overcome these challenges, we will study the locomotion and transport of magnetically guided catalytic microswimmers in biofluids under microfluidic confinement using a combination of computational modeling and experiment. The catalytic microswimmers exploit surface asymmetry and short-range interactions with the surrounding chemical field to generate self-propelled motion. We hypothesize that catalytic microswimmers can be precisely guided through biofluids using externally applied magnetic fields. We will develop a hybrid computational model that combines multiparticle collision dynamics with finite difference method to test this hypothesis. This model, which incorporates hydrodynamics, thermal fluctuations, and phoretic interactions within biofluids, will enable a detailed investigation of how fluid properties like viscous heterogeneity, shear-thinning viscosity, viscoelasticity, and anisotropy affect the propulsion, orientation, and trajectory of microswimmers. By systematically analyzing swimmer–wall, swimmer–flow, and swimmer–magnetic field interactions in biofluids, the computational model will help identify optimal parameters such as swimming speed, magnetic field strength and direction, and microswimmer shape to achieve controlled navigation. Experimentally, we will fabricate catalytic microswimmers of various shapes and study their motion in microfluidic devices containing synthetic biofluids such as polymeric and mucus-analog solutions. We will use external light to activate or deactivate propulsion, enabling control over the swimming speed of the microswimmer, while an external magnetic field will be used to control its orientation. Building on simulation results, we will perform microfluidic experiments to achieve control over swimmer's speed and orientation using light and magnetic fields, and track their trajectories using high-resolution imaging. This study will provide fundamental insights into microswimmer locomotion and transport in confined biofluids. Based on this understanding, we aim to build a microfluidic device that enables controlled navigation of catalytic microswimmers in biofluids, with significant potential for biomedical applications.