A fine balance of chemotactic and hydrodynamic torques: when microswimmers orbit a pillar just once

Abstract

We study the detention statistics of self-propelling droplet microswimmers attaching to microfluidic pillars. These droplets show negative autochemotaxis: they shed a persistent repulsive trail of spent fuel that biases them to detach from pillars of a certain size after orbiting them just once. We have designed a microfluidic assay recording swimmers in pillar arrays of varying diameter, derived detention statistics via digital image analysis and interpreted these statistics via the Langevin dynamics of an active Brownian particle (ABP) model. By comparing data from orbits with and without residual chemical field, we can independently estimate quantities like hydrodynamic and chemorepulsive torques, chemical coupling constants and diffusion coefficients, as well as their dependence on boundary conditions like wall curvature.

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• Chemotactic self-caging in active emulsions
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• Design of nematic liquid crystals to control microscale dynamics
• Active Brownian and inertial particles in disordered environments: short-time expansion of the mean-square displacement
• Alignment and scattering of colliding active droplets
• Confined self-propulsion of an isotropic active colloid
• Deflection of phototactic microswimmers through obstacle arrays
• Unsteady chiral swimmer in presence of an external chemical gradient
• Premelting controlled active matter in ice
• Biolocomotion and premelting in ice
• A numerical framework for phoretic particles