Experiments with active and driven synthetic colloids in complex fluids

In this review, we focus on recent experimental research involving active colloidal particles of non-biological origin evolving in non-Newtonian fluids. This includes self-propelling active particles and particles driven by external fields. We present different propulsion strategies that are either enabled, or strongly modified, by the presence of a complex medium. This paves the way for novel mechanisms of active transport in biofluids or in other non-Newnotian fluids. When considering the medium, we differentiate between disordered complex fluids, such as diluted polymer solutions, and liquid crystals. While the latter are also viscoelastic fluids, the ability to control their molecular orientation results in distinct colloidal driving and steering mechanisms, and enables new types of active soft matter in the form of active quasi-particles.

Automated summary

In this review, recent experimental research on active colloidal particles in non-Newtonian fluids is focused. Different propulsion strategies, enabled or modified by the presence of a complex medium, are presented. This provides new insights into active transport in biofluids or other non-Newtonian fluids. The differentiation between disordered complex fluids and liquid crystals, considering their distinct colloidal driving and steering mechanisms, leads to the development of active quasi-particles.