Hot Brownian Motion

Rings, Daniel; Schachoff, Romy; Selmke, Markus; Cichos, Frank; Kroy, Klaus

doi:10.1103/physrevlett.105.090604

Cited by 185 publications

(211 citation statements)

References 30 publications

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“…Brownian motion in nonequilibrium systems is of particular interest because it is directly related to the transport of molecules and cells in biological systems. Important examples include Brownian motors [38,39], active Brownian motion of self-propelled particles [40][41][42][43][44][45][46], hot Brownian motion [47], and Brownian motion in shear flows [48]. Recent theoretical studies also found that the inertias of particles and surrounding fluids can significantly affect the Brownian motion in nonequilibrium systems [49][50][51][52][53][54].…”

Section: Introductionmentioning

confidence: 99%

Brownian motion at short time scales

2013

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Brownian motion has played important roles in many different fields of science since its origin was first explained by Albert Einstein in 1905. Einstein's theory of Brownian motion, however, is only applicable at long time scales. At short time scales, Brownian motion of a suspended particle is not completely random, due to the inertia of the particle and the surrounding fluid. Moreover, the thermal force exerted on a particle suspended in a liquid is not a white noise, but is colored. Recent experimental developments in optical trapping and detection have made this new regime of Brownian motion accessible. This review summarizes related theories and recent experiments on Brownian motion at short time scales, with a focus on the measurement of the instantaneous velocity of a Brownian particle in a gas and the observation of the transition from ballistic to diffusive Brownian motion in a liquid.

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Section: Introductionmentioning

confidence: 99%

Brownian motion at short time scales

2013

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“…[5]. More recently, the Brownian motion of a small heated sphere, a so-called hot particle, has been investigated [6,7]. The authors discovered that the particle diffusion has distinct features from the case of diffusion in isothermal systems.…”

Section: Introductionmentioning

confidence: 99%

“…To model experiments on the motion of a heated particle [7], the continuous spatial variation of viscosity was approximated by Chakraborty et al [6] using a set of spherical shells of monotonically changing but constant viscosity. Since the solution to the constant viscosity problem is straightforward, multiple such solutions can be stitched together.…”

Section: Introductionmentioning

confidence: 99%

Motion of a hot particle in viscous fluids

2016

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We study the motion of a hot particle in a viscous liquid at low Reynolds numbers, which is inspired by recent experiments with Brownian particles heated by a laser. The difference in temperature between a particle and the ambient fluid causes a spatial variation of the viscosity in the vicinity of the solid body. We derive a general analytical expression determining the force and the torque on a particle for low Péclet numbers by exploiting the Lorentz reciprocal theorem. For small temperature and viscosity variations, a perturbation analysis is implemented to evaluate the leading-order correction to the hydrodynamic force and torque on the particle. The results are applied to describe dynamics of a uniformly hot spherical particle and to spherical particles with a nonuniform surface temperature described by dipole and quadrupole moments. Among other results, we find for dipolar thermal fields that there is coupling of the translational and rotational motions when there are local viscosity variations; such coupling is absent in an isothermal fluid.

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“…The optical forces acting on the particle are calculated using generalized Mie theory [23]. The temperature increase in the surroundings of the particle is calculated by determining the absorption of the laser light by the iron oxide inclusions [25] and by using the stationary heat equation to estimate the ensuing heat conduction [26]. This temperature increase causes a local demixing of the binary solution near the particle resulting in an increase in the local concentration of water, because of the hydrophilicity of the particle's surface.…”

Section: Numerical Simulationsmentioning

confidence: 99%

Microscopic Engine Powered by Critical Demixing

et al. 2018

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By converting energy into mechanical work, engines play a central role in most biological and technological processes. In particular, within the current trend towards the development of nanoscience and nanotechnology, microscopic engines have been attracting an ever-increasing interest. On the one hand, there has been a quest to understand how biological molecular motors work. On the other hand, several approaches have been proposed to realize artificial microscopic engines, which have been powered by the transfer of light momentum, by external magnetic fields, by in situ chemical reactions, or by the energy flow between hot and cold heat reservoirs, in scaled-down versions of macroscopic heat engines. Here, we experimentally demonstrate a microscopic engine powered by the local reversible demixing of a critical mixture. We show that, when an absorbing microsphere is optically trapped by a focused laser beam in a sub-critical mixture, it is set into rotation around the optical axis of the beam because of the emergence of diffusiophoretic propulsion; this behavior can be controlled by adjusting the optical power, the temperature, and the criticality of the mixture. Given its simplicity, this microscopic engine provides a powerful tool to power micro-and nanodevices. Furthermore, since many biological systems are tuned near criticality, this mechanism might already be at work within living organisms, for example in proteins and in cellular membranes.

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Hot Brownian Motion

Cited by 185 publications

References 30 publications

Brownian motion at short time scales

Brownian motion at short time scales

Motion of a hot particle in viscous fluids

Microscopic Engine Powered by Critical Demixing

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