Work Extraction and Performance of Colloidal Heat Engines in Viscoelastic Baths

Abstract

A colloidal particle embedded in a fluid can be used as a microscopic heat engine by means of a sequence of cyclic transformations imposed by an optical trap. We investigate a model for the operation of such kind of Brownian engines when the surrounding medium is viscoelastic, which endows the particle dynamics with memory friction. We analyze the effect of the relaxation time of the fluid on the performance of the colloidal engine under finite-time Stirling cycles. We find that, due to the frequency-dependence of the friction in viscoelastic fluids, the mean power delivered by the engine and its efficiency can be highly enhanced as compared to those in a viscous environment with the same zero-shear viscosity. In addition, with increasing fluid relaxation time the interval of cycle times at which positive power output can be delivered by the engine broadens. Our results reveal the importance of the transient behavior of the friction experienced by a Brownian heat engine in a complex fluid, which cannot be neglected when driven by thermodynamic cycles of finite duration.

Enhanced directionality of active processes in a viscoelastic bath

“…Here τ is the relaxation time of the fluid, γ 0 and γ are the solvent and the polymer contributions of the frictional coefficient, respectively [70]. Notably, the memory kernel will be viscous-like (delta-correlated) in the τ → 0 limit as discussed in [47,52]. Hereafter, we refer to this limit as the viscous limit.…”

“…Similarly, recent experiments have shown several intriguing phenomena related to the dynamics of an embedded particle as well as swimmers in viscoelastic fluids [45,46]. These observations include the increase in Kramer's rate of transitions [47][48][49], circular motion of active particles instead of only persistent random walks [50,51], increase in the rotational diffusion coefficient of an active Brownian particle by orders of magnitude compared to that in a viscous fluid [51], and very interestingly, the possibility of attaining the Carnot efficiency in microscopic sterling engine [52]. Several recent studies also show that viscoelasticity is essential for facilitating various biological processes [35,53,54].…”

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

“…For example, viscoelasticity increases Kramer's rate of transition [27,28], active particles show circular motion in a viscoelastic bath instead of only persistent random walks [29,30], the rotational diffusion coefficient of an active Brownian particle in a viscoelastic bath increases by orders of magnitude compared to that in a viscous fluid [30], and very interestingly, the efficiency of the microscopic sterling engine operates in a viscoelastic fluid can reach Carnot efficiency [31]. Remarkably, some recent studies also show that viscoelasticity is essential for the facilitation of various biological processes [32][33][34].…”

Geometric Brownian Information Engine: Essentials for the best performance

“…These developments emanated the notion of information engines, a system that extracts work from a single heat bath using the mutual information earned by the measurement. Execution of a feedback protocol [7][8][9][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26], however not limited to [27][28][29][30][31], is a widely popular mechanism to devise an information engine. Due to their consequences in living systems, several variants of information engines at the mesoscopic level have been studied theoretically, both classical [12][13][14] and quantum systems [7,[15][16][17], and validated through experiments [20,[22][23][24][25][26].…”