Single-shot wideband active microrheology using multiple-sinusoid modulated optical tweezers

Kundu, Avijit; Dey, Raunak; Paul, S.; Banerjee, Ayan

doi:10.1103/physrevfluids.6.123301

Cited by 3 publications

(5 citation statements)

References 49 publications

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“…Notably, the variance can be determined from the equipartition of energy which does not depend at all on the rheological properties of the surrounding medium in equilibrium. Therefore, it can be used in experiments for measuring the trap stiffness reliably even in a viscoelastic fluid [25,26].…”

Section: Resultsmentioning

confidence: 99%

“…Therefore, energy dissipation in a viscoelastic fluid is less compared to that in a viscous fluid. Markedly, as opposed to a viscous fluid -together with the dissipation, energy also gets stored in a viscoelastic fluid [24][25][26]. The changes of the variance σ 11 with the fluid relaxation time τ for various noise strengths are shown in Fig.…”

Section: Resultsmentioning

confidence: 99%

“…Here, we must note that a viscoelastic background is a reality for most of the environments expected for chemical or biological applications due to the present microstructures of polymers, bio-molecular chains, colloids, wormlike micelles, etc [20][21][22][23]. Contrary to purely Newtonian fluids, where energy only gets dissipated, a viscoelastic medium can store energy due to its non-zero elasticity [24][25][26]. This leads to memory effects of large relaxation times, which consequently shows several intriguing phenomena related to the dynamics of an embedded particle in such fluids.…”

Section: Introductionmentioning

confidence: 99%

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Work fluctuations of Brownian harmonic oscillators driven by "active-like'' viscoelastic baths

Das¹,

Banerjee²,

Paul³

2023

Preprint

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We experimentally and theoretically investigate the dynamics and work fluctuations of an optically trapped micro-particle in a viscoelastic medium driven by an external Ornstein-Uhlenbeck (OU) noise. Compared to a viscous medium of the same zero-shear viscosity, we find a significant increase (∼ 50%) in the mean transferred power from the external forcing of a fixed noise strength to the particle due to the slow relaxation process of the viscoelastic medium considered in this study. The memory of the viscoelastic medium also leads to a small increase in the effective temperature of the particle and a high fluctuation in the work done by the external forcing. Consequently, as opposed to a viscous medium, negative work-fluctuations reduce extremely fast. This leads to the violation of the work fluctuation theorem (WFT) for a very small external noise, which may even be only ∼ 25% of the thermal noise strength in a non-Markovian viscoelastic bath. We further show that all the experimental findings can be described excellently from the Langevin dynamics of the process. Finally, we formulate the appropriate WFT for such a system from the calculated work probability density function.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Work fluctuations of Brownian harmonic oscillators driven by "active-like'' viscoelastic baths

Das¹,

Banerjee²,

Paul³

2023

Preprint

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“…Further experimental and theoretical efforts based on this model system could help to investigate other relevant aspects on the stochastic energetics at strong coupling under more intricate conditions, e.g. in thermally-activated escape processes over energetic barriers with memory friction [98], the efficiency of cyclic Brownian engines operating in non-Newtonian fluids [63,65,66], and work fluctuations of colloids periodically or stochastically driven in viscoelastic media [99,100]. stationarity of the system at thermal equilibrium.…”

Section: Summary and Concluding Remarksmentioning

confidence: 99%

Stochastic energetics of a colloidal particle trapped in a viscoelastic bath

Darabi,

Ferrer,

Gomez-Solano

2023

New J. Phys.

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We investigate the statistics of the fluctuations of the energy transfer between an overdamped Brownian particle, whose motion is confined by a stationary harmonic potential, and a surrounding viscoelastic fluid at constant temperature. We derive an analytical expression for the probability density function of the energy exchanged with the fluid over a finite time interval, which implicitly involves the friction memory kernel that encodes the coupling with such a non-Markovian environment, and reduces to the well known expression for the heat distribution in a viscous fluid. We show that, while the odd moments of this distribution are zero, the even moments can be explicitly expressed in terms of the autocorrelation function of the particle position, which generally exhibits a non-mono-exponential decay when the fluid bath is viscoelastic. Our results are verified by experimental measurements for an optically-trapped colloidal bead in semidilute micellar and polymer solutions, finding and excellent agreement for all time intervals over which the energy exchange takes place.

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“…This viscoelasticity arises from the intricate composition and structure of the cellular environment, characterized by a combination of viscous and elastic properties [26,27]. This also leads to memory effects due to the large relaxation times, which again breaks the effective Markovian description for the dynamics of the system [28][29][30][31][32][33].…”

Section: Introductionmentioning

confidence: 99%

Enhanced directionality of active processes in a viscoelastic bath

Das,

Paul,

Manikandan

et al. 2023

New J. Phys.

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Active fluctuations are known to play a significant role in the intracellular transport of passive objects. However, the effect of viscoelasticity of the environment in shaping such processes is relatively less understood. Here, with a minimal experiment using a driven colloid in a viscoelastic bath, we show that viscoelasticity significantly increases the mean injected power to the passive object (~ 50% compared to a viscous medium), for the same strength of the external driving. Additionally, we observe a notable reduction in negative work fluctuations across a wide range of driving amplitudes. These findings collectively suggest an enhanced directionality in driven processes within a viscoelastic bath, which we attribute to the emergence of interactions between the colloid and the viscoelastic medium.

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Single-shot wideband active microrheology using multiple-sinusoid modulated optical tweezers

Cited by 3 publications

References 49 publications

Work fluctuations of Brownian harmonic oscillators driven by "active-like'' viscoelastic baths

Work fluctuations of Brownian harmonic oscillators driven by "active-like'' viscoelastic baths

Stochastic energetics of a colloidal particle trapped in a viscoelastic bath

Enhanced directionality of active processes in a viscoelastic bath

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