Dynamic clustering of passive colloids in dense suspensions of motile bacteria.

Gokhale, Shreyas; Li, Junang; Solon, Alexandre; Gore, Jeff; Fakhri, Nikta · Phys Rev E · 2022

basic_science · Level V

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Abstract

Mixtures of active and passive particles are predicted to exhibit a variety of nonequilibrium phases. Here we report a dynamic clustering phase in mixtures of colloids and motile bacteria. We show that colloidal clustering results from a balance between bond breaking due to persistent active motion and bond stabilization due to torques that align active particle velocity tangentially to the passive particle surface. Furthermore, dynamic clustering spans a broad regime between diffusivity-based and motility-induced phase separation that subsumes typical bacterial motility parameters.