Evolving Motility of Active Droplets is Captured by a Self-Repelling Random Walk Model

Physical Review Letters, Journal Year: 2025, Volume and Issue: 134(1)

Published: Jan. 3, 2025

In living matter, concentration gradients of nutrients carve the motility microorganisms in a heterogeneous environment. Here, we use swimming droplets as model system to study how swimmer-trail interactions guide locomotion. Combining experiments and theory, show that our non-Markovian droplet quantitatively captures motility. The two fit parameters provide first estimate effective temperature arising from hydrodynamic flows coupling strength propulsion force. This framework is general explains memory effects, hovering, enhanced collective motion.

Language: Английский

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Profile-Preserving Phase-Field Model for Surfactant Transport and Adsorption-Desorption in Two-Phase Flow Systems

Published: Jan. 1, 2025

Language: Английский

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Weakly nonlinear dynamics of a chemically active particle near the threshold for spontaneous motion. II. History-dependent motion

Physical Review Fluids, Journal Year: 2023, Volume and Issue: 8(3)

Published: March 13, 2023

Isotropic chemically active particles can spontaneously self-propel owing to a symmetry-breaking instability when diffusion of the chemical is sufficiently weak relative advection. This series revisits weakly nonlinear theory describing dynamics such spontaneous swimmers near threshold. Part II presents an extension general framework from part I include unsteadiness in form integral over history particle motion, representing interaction with its own wake. allows efficient simulation and theoretical analysis fully three-dimensional unsteady problems range physical scenarios.

Language: Английский

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Deforming active droplets in viscoelastic solutions

Soft Matter, Journal Year: 2023, Volume and Issue: 19(21), P. 3783 - 3793

Published: Jan. 1, 2023

The motion of biological swimmers in typical bodily fluids is modelled using a system micellar solubilization driven active droplets viscoelastic polymeric solution. nature the medium, as perceived by moving droplet, characterized Deborah number (De), tuned varying surfactant (fuel) and polymer concentration ambient medium. At moderate De, droplet exhibits steady deformed shape, markedly different from spherical shape observed Newtonian media. A theoretical analysis based on normal stress balance at interface shown to accurately predict shape. With further increase time-periodic deformation accompanied an oscillatory transition swimming mode observed. study unveils hitherto unexplored rich complexity fluids.

Language: Английский

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Non-Brownian diffusion and chaotic rheology of autophoretic disks

Physical review. E, Journal Year: 2023, Volume and Issue: 107(4)

Published: April 27, 2023

The dynamics of a two-dimensional autophoretic disk is quantified as minimal model for the chaotic trajectories undertaken by active droplets. Via direct numerical simulations, we show that mean-square displacement in quiescent fluid linear at long times. Surprisingly, however, this apparently diffusive behavior non-Brownian, owing to strong cross correlations tensor. effect shear flow field on motion an examined. Here, stresslet weak flows; dilute suspension such disks would exhibit rheology. This rheology quenched first into periodic state and ultimately steady strength increased.

Language: Английский

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Coupled bulk and interfacial transport of surfactants governs the settling of a drop towards a wall

Journal of Fluid Mechanics, Journal Year: 2024, Volume and Issue: 987

Published: May 24, 2024

Surfactant-like impurities are omnipresent in multiphase emulsions and may substantially affect the motion of small droplets by altering their interfacial properties. Usually these surfactants soluble bulk undergo adsorption–desorption onto interface which modifies surface concentration hence overall influence on droplet motion. Yet, impact solubility transport dynamics, especially presence bounding walls, remains poorly understood. As such, this article, we assess settling a spherical drop towards plane wall. We consider coupled surfactants, mediated processes construct semi-analytical framework for arbitrary values ‘bulk interaction parameter’, dictates strength kinetics compared with diffusion. Our results indicate that while mass exchange between can remobilize drop, finite diffusion rate restricts process therefore slows down drop. This also depletion near south pole accumulation north pole, extent becomes strongly asymmetric an enhanced intensity depletion, as approaches Presence wall found to aid each other remobilizing aptly modifying concentration. provide fundamental insights into surfactant-laden drops, potential applications food pharmaceutical industries, separation processes, etc.

Language: Английский

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Chemical Programming of Solubilizing, Nonequilibrium Active Droplets

Accounts of Chemical Research, Journal Year: 2024, Volume and Issue: 57(16), P. 2372 - 2382

Published: Aug. 8, 2024

ConspectusThe multifunctionality and resilience of living systems has inspired an explosion interest in creating materials with life-like properties. Just as life persists out-of-equilibrium, we too should try to design that are thermodynamically unstable but can be harnessed achieve desirable, adaptive behaviors. Studying minimalistic chemical exhibit relatively simple emergent behaviors, such motility, communication, or self-organization, provide insight into fundamental principles which may enable the more complex synthetic future.Emulsions, composed liquid droplets dispersed another immiscible fluid phase, have emerged fascinating chemically minimal study nonequilibrium, As covered this Account, our group focused on studying oil-in-water emulsions, specifically those destabilize by solubilization, a process wherein oil is released continuous phase over time create gradients oil-filled micelles. These interfacial tension lead droplet self-propulsion well mediate communication between neighboring droplets. such, emulsions present interesting platform for active matter. However, despite being sometimes few three chemicals (oil, water, surfactant), surprising complexity across molecular macroscale. Fundamental processes governing their behavior, micelle-mediated transport, still not understood. This compounded challenges out-of-equilibrium typically require new analytical methods break intuition derived from equilibrium thermodynamics.In highlight group's efforts toward developing frameworks understanding interactive emulsions. How do properties physical spatial organization oil, surfactant combine yield colloidal-scale properties? Our tackles question employing systematic studies behavior working space oils surfactants link structure behavior. The Account begins introduction single, isolated how applying biases, gravitational field interfacially adsorbed particles, drop speeds manipulated. Next, illustrate some attractive, self-propulsive/repulsive, does fall line current impact micelle tensions. mechanisms micelles influence tensions nonequilibrium interfaces poorly understood requires deeper understanding. Regardless, extend knowledge motility nonreciprocal predator–prey interactions describe dynamic self-organization arises combination reciprocal Finally, progress answering key questions surrounding remain answered. We hope help inform research tangential areas cell biology origins life.

Language: Английский

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Electrotaxis of Self-Propelling Artificial Swimmers in Microchannels

Physical Review Letters, Journal Year: 2024, Volume and Issue: 133(15)

Published: Oct. 7, 2024

Biological microswimmers alter their swimming trajectories to follow the direction of an applied electric field, exhibiting electrotaxis. We show that synthetic active droplet also autonomously change in microchannels, even undergoing "U-turns," response mimicking exploit such electrotaxis, presence external flow, robustly tune trajectory droplets between wall-adjacent, oscillatory, and channel centerline swimming. A general hydrodynamic model demonstrates electrotactic dynamics is governed by electrical effects due swimmer's inherent surface charge, besides its motility, wall interactions, relative orientations field imposed flow. Our study a simple method for controlling agents complex geometries microrobotic applications, like autonomous cargo delivery.

Language: Английский

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Mode switching of active droplets in macromolecular solutions

Soft Matter, Journal Year: 2023, Volume and Issue: 19(22), P. 4099 - 4108

Published: Jan. 1, 2023

Typical bodily and environmental fluids encountered by biological swimmers consist of dissolved macromolecules such as proteins or polymers, rendering them even non-Newtonian at times. Active droplets mimic the essential propulsive characteristics several swimmers, serve ideal model systems to widen our understanding their locomotive strategies. Here, we investigate motion a micellar solubilization driven active oil droplet in an aqueous medium consisting polymers macromolecular solutes. Experiments reveal extreme sensitivity presence its ambient medium. Through situ visualization self-generated chemical field around droplet, notice unexpectedly high diffusivity filled micelles molecular weight polymeric This highlights breakdown continuum approximation due significant size difference between solutes micelles. It is shown that Péclet number, defined based on experimentally determined micelle (taking into account local solvent viscosity) successfully captures transition from smooth jittery propulsion mode for both With increase solute concentration, particle image velocimetry reveals another switching conventional pusher puller propulsion, characterized more persistent motion. By doping with suitable choice macromolecules, experiments unveil novel route orchestrate complex transitions propulsion.

Language: Английский

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Dynamic partitioning of surfactants into non-equilibrium emulsion droplets

Published: July 14, 2023

Emulsion droplets, such as oil-in-water droplets stabilized by surfactant, are ubiquitous in products ranging from food to pharmaceuticals paints. However, emulsion often thermodynamically unstable and thus persist under non-equilibrium conditions for extended times. As such, equilibrium properties like partition coefficients or interfacial tensions may be inadequate describe the of an out-of-equilibrium droplet that can potentially experience not accessible at equilibrium. Here, partitioning nonionic surfactants between microscale oil water is investigated wherein shrinking volume over time via solubilization. Quantitative mass spectrometry used analyze composition individual micro-droplets a function varying diameter, surfactant molecular structure concentration, structure. We find common into timescale minutes reach steady state; this state concentration orders magnitude higher than aqueous phase what conditions. Using kinetic data apparent coefficients, we distribution using transfer model. Over longer timescales hours, sheds accumulated back water, creating transiently high concentrations near interface which leads evolution ultralow tension. Introduction ionic forms mixed micelles with reduces oil; based on observation, use stimuli-responsive trigger separation mixing inside modulation partitioning. This study reveals generalizable states experienced solubilizing govern properties.

Language: Английский

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