Self-propulsion of chemically-active droplets

Abstract

Microscopic active droplets are able to swim autonomously in viscous flows: this puzzling feature stems from solute exchanges with the surrounding fluid via surface reactions or their spontaneous solubilisation, and the interfacial flows resulting from these solutes' gradients. Contrary to asymmetric active colloids, these isotropic droplets swim spontaneously by exploiting the nonlinear coupling of solute transport with self-generated Marangoni flows, which is also responsible for secondary transitions to more complex individual and collective dynamics. Thanks to their simple design and their sensitivity to physico-chemical signals, they are fascinating physicists, chemists, biologists and fluid dynamicists alike to analyse viscous self-propulsion and collective dynamics in active matter systems, to develop synthetic cellular models or to perform targeted biomedical or engineering applications. I review here the most recent and significant developments of this rapidly-growing field, focusing on the mathematical and physical modelling of these intringuing droplets, together with its experimental design and characterisation.

arXiv comment26 pages, 8 figures, to appear in Annual Review of Fluid Mechanics

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Cited by in corpus (34)

• We the Droplets: A Constitutional Approach to Active and Self-Propelled Emulsions
• A review of active matter reviews
• Enzyme-enriched condensates show self-propulsion, positioning, and coexistence
• The 2024 Motile Active Matter Roadmap
• Self-solidifying active droplets showing memory-induced chirality
• Self-consistent sharp interface theory of active condensate dynamics
• Bifurcation tracking on moving meshes and with consideration of azimuthal symmetry breaking instabilities
• Dynamics of forced and unforced autophoretic particles
• Deforming Active Droplets in Viscoelastic Media
• Bidirectional Wave-Propelled Capillary Spinners
• Interfacial activity dynamics of confined active droplets
• Anderson localization of walking droplets
• Mode-Switching of Active Droplets in Macromolecular Solutions
• Migration and deformation of a droplet enclosing an active particle
• Non-Brownian diffusion and chaotic rheology of autophoretic disks
• On the theory of body motion in confined Stokesian fluids
• Hydrodynamic efficiency limit on a Marangoni surfer
• Self-organisation of auto-phoretic suspensions in confined shear flows
• Gradient dynamics approach to reactive thin-film hydrodynamics
• Chemical reaction motifs driving non-equilibrium behaviors in phase separating materials
• Simple mathematical model for a pairing-induced motion of active and passive particles
• Fluctuating hydrodynamics of an autophoretic particle near a permeable interface
• Chemomechanical motility modes of partially wetting liquid droplets
• Arrested on heating: controlling the motility of active droplets by temperature
• Temperature switchable self-propulsion activity of liquid crystalline microdroplets
• Gradient dynamics model for chemically driven running drops
• A numerical framework for phoretic particles
• Automated decision-making by chemical echolocation in active droplets
• A Diffuse-Interface Marangoni Instability
• Probing wetting properties with self-propelled droplets
• Non-reciprocal interactions between condensates in chemically active mixtures
• Active adaptolates: motility-induced percolating structures with an adaptive packing geometry
• Energetics-based model for a diffusiophoretic motion of a deformable droplet
• Instability and self-propulsion of flexible autophoretic filaments