Flow Topology During Multiplexed Particle Manipulation Using a Stokes Trap

Shenoy, Anish; Kumar, D. Sriram; Hilgenfeldt, Sascha; Schroeder, Charles M.

doi:10.1103/physrevapplied.12.054010

Cited by 30 publications

(24 citation statements)

References 34 publications

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“…In this paper, we present a detailed flow-phase diagram of non-equilibrium vesicle shape transitions in extensional flow using a Stokes trap [47][48][49], which enables precise control over the center-of-mass position of single or multiple particles in flow. In this way, we directly observe vesicle shape transitions over long observation times across a wide range of parameters including reduced volume ν and capillary number Ca.…”

Section: Introductionmentioning

confidence: 99%

Conformational dynamics and phase behavior of lipid vesicles in a precisely controlled extensional flow

2020

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Lipid vesicles play a key role in fundamental biological processes. Despite recent progress, we lack a complete understanding of the non-equilibrium dynamics of vesicles due to challenges associated with long-time observation of shape fluctuations in strong flows. In this work, we present a flowphase diagram for vesicle shape and conformational transitions in planar extensional flow using a Stokes trap, which enables control over the center-of-mass position of single or multiple vesicles in precisely defined flows [Shenoy, Rao, Schroeder, PNAS, 113(15):3976-3981, 2016]. In this way, we directly observe the non-equilibrium conformations of lipid vesicles as a function of reduced volume ν, capillary number Ca, and viscosity contrast λ. Our results show that vesicle dynamics in extensional flow are characterized by the emergence of three distinct shape transitions, including a tubular to symmetric dumbbell transition, a spheroid to asymmetric dumbbell transition, and quasi-spherical to ellipsoid transition. The experimental phase diagram is in good agreement with recent predictions from simulations [Narsimhan, Spann, Shaqfeh, J. Fluid Mech., 2014, 750, 144]. We further show that the phase boundary of vesicle shape transitions is independent of the viscosity contrast. Taken together, our results demonstrate the utility of the Stokes trap for the precise quantification of vesicle stretching dynamics in precisely defined flows.

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Section: Introductionmentioning

confidence: 99%

Conformational dynamics and phase behavior of lipid vesicles in a precisely controlled extensional flow

2020

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“…In extensional flow, fluid elements separate exponentially in time (Leal 1992), and it is generally not possible to observe a single vesicle in flow for long periods of time in the absence of feedback controllers. Automation in flow control techniques using sophisticated feedback algorithms has recently enabled the precise characterization of vesicle dynamics in elongational flows (Shenoy, Tanyeri & Schroeder 2015;Shenoy, Rao & Schroeder 2016;Shenoy et al 2019;Kumar et al 2019Kumar et al , 2020c.…”

Section: Introductionmentioning

confidence: 99%

“…In this paper, we study the dynamics of single vesicles in LAOE using a combination of microfluidic experiments and boundary integral (BI) simulations. The LAOE experiments are performed using the Stokes trap (Shenoy et al 2016(Shenoy et al , 2019Kumar et al 2019Kumar et al , 2020c, which is a new method for controlling the centre-of-mass position, orientation and trajectories of freely suspended single and multiple vesicles using only fluid flow. We find that single vesicles experience periodic cycles of compression and extension in LAOE with membrane dynamics governed by the dimensionless flow strength capillary number (Ca), reduced volume (measure of vesicle asphericity, ν) and flow frequency Deborah number (De).…”

Section: Introductionmentioning

confidence: 99%

Vesicle dynamics in large amplitude oscillatory extensional flow

et al. 2021

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Although the behaviour of fluid-filled vesicles in steady flows has been extensively studied, far less is understood regarding the shape dynamics of vesicles in time-dependent oscillatory flows. Here, we investigate the nonlinear dynamics of vesicles in large amplitude oscillatory extensional (LAOE) flows using both experiments and boundary integral (BI) simulations. Our results characterize the transient membrane deformations, dynamical regimes and stress response of vesicles in LAOE in terms of reduced volume (vesicle asphericity), capillary number ( ${Ca}$ , dimensionless flow strength) and Deborah number ( ${De}$ , dimensionless flow frequency). Results from single vesicle experiments are found to be in good agreement with BI simulations across a wide range of parameters. Our results reveal three distinct dynamical regimes based on vesicle deformation: pulsating, reorienting and symmetrical regimes. We construct phase diagrams characterizing the transition of vesicle shapes between pulsating, reorienting and symmetrical regimes within the two-dimensional Pipkin space defined by ${De}$ and ${Ca}$ . Contrary to observations on clean Newtonian droplets, vesicles do not reach a maximum length twice per strain rate cycle in the reorienting and pulsating regimes. The distinct dynamics observed in each regime result from a competition between the flow frequency, flow time scale and membrane deformation time scale. By calculating the particle stresslet, we quantify the nonlinear relationship between average vesicle stress and strain rate. Additionally, we present results on tubular vesicles that undergo shape transformation over several strain cycles. Broadly, our work provides new information regarding the transient dynamics of vesicles in time-dependent flows that directly informs bulk suspension rheology.

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“…In extensional flow, fluid elements separate exponentially in time [30], and it is generally not possible to observe a single vesicle in flow for long periods of time in the absence of feedback controllers. Automation in flow control techniques using sophisticated feedback algorithms has recently enabled the precise characterization of vesicle dynamics in elongational flows [28,29,[45][46][47]. In a steady extensional flow, it is known that highly deflated tubular vesicles undergo a conformation change to a symmetric dumbbell shape [21,26,37,38] while moderately deflated vesicles transition to an asymmetric dumbbell shape [9,26].…”

Section: Introductionmentioning

confidence: 99%

Vesicle dynamics in large amplitude oscillatory extensional flow

Lin,

Kumar,

Richter

et al. 2021

Preprint

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Although the behavior of fluid-filled vesicles in steady flows has been extensively studied, far less is understood regarding the shape dynamics of vesicles in time-dependent oscillatory flows. Here, we investigate the nonlinear dynamics of vesicles in large amplitude oscillatory extensional (LAOE) flows using both experiments and boundary integral (BI) simulations. Our results characterize the transient membrane deformations, dynamical regimes, and stress response of vesicles in LAOE in terms of reduced volume (vesicle asphericity), capillary number (Ca, dimensionless flow strength), and Deborah number (De, dimensionless flow frequency). Results from single vesicle experiments are found to be in good agreement with BI simulations across a wide range of parameters. Our results reveal three distinct dynamical regimes based on vesicle deformation: pulsating, reorienting, and symmetrical regimes. We construct phase diagrams characterizing the transition of vesicle shapes between pulsating, reorienting, and symmetrical regimes within the two-dimensional Pipkin space defined by De and Ca. Contrary to observations on clean Newtonian droplets, vesicles do not reach a maximum length twice per strain rate cycle in the reorienting and pulsating regimes. The distinct dynamics observed in each regime result from a competition between the flow frequency, flow time scale, and membrane deformation timescale. By calculating the particle stresslet, we quantify the nonlinear relationship between average vesicle stress and strain rate. Additionally, we present results on tubular vesicles that undergo shape transformation over several strain cycles. Broadly, our work provides new information regarding the transient dynamics of vesicles in time-dependent flows that directly informs bulk suspension rheology.

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Flow Topology During Multiplexed Particle Manipulation Using a Stokes Trap

Cited by 30 publications

References 34 publications

Conformational dynamics and phase behavior of lipid vesicles in a precisely controlled extensional flow

Conformational dynamics and phase behavior of lipid vesicles in a precisely controlled extensional flow

Vesicle dynamics in large amplitude oscillatory extensional flow

Vesicle dynamics in large amplitude oscillatory extensional flow

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