Self-propulsion in a low Reynolds number world: Thermophoretic microswimmers and Chemotactic microbes

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Ankush Sengupta
06/01/2016 - 10:30
Bldg. 202, Room 301 (Colloquium Room)
Microswimmers are microscopic objects that self-propel in a fluid. Synthetic microswimmers, designed with active colloids, propel by various driving mechanisms, for example, in response to a solute concentration gradient (diffusiophoresis), or a temperature gradient (thermophoresis), or through the manipulation of an external magnetic field. Janus colloids propelled by light, e.g., thermophoretic particles, offer promising prospects as artificial microswimmers. However, their swimming behavior and its dependence on fluid properties and fluid–colloid interactions remain poorly understood. Employing the energy-conserving dissipative particle dynamics simulations, we investigate the behavior of a thermophoretic Janus colloid in its own temperature gradient. In particular, we explore the effects of non-ideal and ideal-gas like fluids for different fluid-colloid interactions, boundary conditions and different temperature-control strategies. Given that these microswimmers need to perform in a highly fluctuating low Reynolds number world, our study brings forth the factors that can modify and control their dynamics.