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Patil G, Mandal P, Ghosh A. Using the Thermal Ratchet Mechanism to Achieve Net Motility in Magnetic Microswimmers. Phys Rev Lett 2022; 129:198002. [PMID: 36399724 DOI: 10.1103/physrevlett.129.198002] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Revised: 09/12/2022] [Accepted: 10/07/2022] [Indexed: 06/16/2023]
Abstract
Thermal ratchets can extract useful work from random fluctuations. This is common in the molecular scale, such as motor proteins, and has also been used to achieve directional transport in microfluidic devices. In this Letter, we use the ratchet principle to induce net motility in an externally powered magnetic colloid, which otherwise shows reciprocal (back and forth) motion. The experimental system is based on ferromagnetic micro helices driven by oscillating magnetic fields, where the reciprocal symmetry is broken through asymmetric actuation timescales. The swimmers show net motility with an enhanced diffusivity, in agreement with the numerical calculations. This new class of microscale, magnetically powered, active colloids can provide a promising experimental platform to simulate diverse active matter phenomena in the natural world.
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Affiliation(s)
- Gouri Patil
- Department of Physics, Indian Institute of Science, Bangalore 560012, India
| | - Pranay Mandal
- Centre for Nano Science and Engineering, Indian Institute of Science, Bangalore 560012, India
| | - Ambarish Ghosh
- Centre for Nano Science and Engineering, Indian Institute of Science, Bangalore 560012, India
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Oh I, Song J, Hyun HR, Lee SH, Kim JS. Brownian ratchet for directional nanoparticle transport by repetitive stretch-relaxation of DNA. Phys Rev E 2022; 106:054117. [PMID: 36559375 DOI: 10.1103/physreve.106.054117] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2022] [Accepted: 10/13/2022] [Indexed: 06/17/2023]
Abstract
Brownian motion subject to a periodic and asymmetric potential can be biased by external, nonequilibrium fluctuations, leading to directional movement of Brownian particles. Sequence-dependent flexibility variation along double-stranded DNA has been proposed as a tool to develop periodic and asymmetric potentials for DNA binding of cationic nanoparticles with sizes below tens of nanometers. Here, we propose that repetitive stretching and relaxation of a long, double-stranded DNA molecule with periodic flexibility gradient can induce nonequilibrium fluctuations that tune the amplitude of asymmetric potentials for DNA-nanoparticle binding to result in directional transport of nanometer-sized particles along DNA. Realization of the proposed Brownian ratchet was proven by Brownian dynamics simulations of coarse-grained models of a single, long DNA molecule with flexibility variation and a cationic nanoparticle.
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Affiliation(s)
- Inrok Oh
- LG Chem Ltd, LG Science Park, Seoul 07796, Republic of Korea
| | - Jeongeun Song
- Department of Chemistry and Nanoscience, Ewha Womans University, Seoul 03760, Republic of Korea
| | - Hye Ree Hyun
- Department of Chemistry and Nanoscience, Ewha Womans University, Seoul 03760, Republic of Korea
| | - Sang Hak Lee
- Department of Chemistry, Pusan National University, Busan 46241, Republic of Korea
| | - Jun Soo Kim
- Department of Chemistry and Nanoscience, Ewha Womans University, Seoul 03760, Republic of Korea
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Fan Q, Guo Y, Zhao S, Bao B. Generation of liquid metal double emulsion droplets using gravity-induced microfluidics. RSC Adv 2022; 12:20686-20695. [PMID: 35919154 PMCID: PMC9295136 DOI: 10.1039/d2ra04120k] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2022] [Accepted: 07/07/2022] [Indexed: 11/21/2022] Open
Abstract
Several microfluidic applications are available for liquid metal droplet generation, but the surface oxidation of liquid metal has placed limitations on its application. Multiphase microfluidics makes it possible to protect the inner droplets by producing the structure of double emulsion droplets. Thus, the generation of liquid metal double emulsion droplets has been developed to prevent the surface oxidation of Galinstan. However, the generation using common methods faces considerable challenges due to the gravity effect introduced from the high density of liquid metal, making it difficult for the shell phase to wrap the inner phase. To overcome this obstacle, we introduce an innovative method – a gravity-induced microfluidic device – to creatively generate controllable liquid metal double emulsion droplets, achieved by altering the measurable inclination angle of the plane. It is found that when the inclination angle ranges from 30° to 45°, the device manages to generate liquid metal double emulsion droplets with perfect double sphere-type configuration. Additionally, the core–shell liquid metal hydrogel capsules present potential applications as multifunctional materials for controlled release systems in drug delivery and biomedical applications. By regulating pH or imposing mechanical force, the hydrogel shell can be dissolved to recover the electrical conductivity of Galinstan for applications in flexible electronics, self-healing conductors, elastomer electronic skin, and tumor therapy. An innovative method – a gravity-induced microfluidic device – to generate liquid metal double emulsion droplets to prevent the formation of an oxide layer on the liquid metal is introduced.![]()
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Affiliation(s)
- Qiyue Fan
- State Key Laboratory of Chemical Engineering and School of Chemical Engineering, East China University of Science and Technology, Shanghai, 200237, China
| | - Yaohao Guo
- State Key Laboratory of Chemical Engineering and School of Chemical Engineering, East China University of Science and Technology, Shanghai, 200237, China
| | - Shuangliang Zhao
- State Key Laboratory of Chemical Engineering and School of Chemical Engineering, East China University of Science and Technology, Shanghai, 200237, China
- Guangxi Key Laboratory of Petrochemical Resource Processing and Process Intensification Technology and School of Chemistry and Chemical Engineering, Guangxi University, Nanning, 530004, China
| | - Bo Bao
- State Key Laboratory of Chemical Engineering and School of Chemical Engineering, East China University of Science and Technology, Shanghai, 200237, China
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Humenyuk YA, Kotrla M, Netočný K, Slanina F. Separation of dense colloidal suspensions in narrow channels: A stochastic model. Phys Rev E 2020; 101:032608. [PMID: 32289907 DOI: 10.1103/physreve.101.032608] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Accepted: 03/06/2020] [Indexed: 06/11/2023]
Abstract
The flow of a colloidal suspension in a narrow channel of periodically varying width is described by the one-dimensional generalized asymmetric exclusion process. Each site admits multiple particle occupancy. We consider particles of two different sizes. The sites available to particles form a comblike geometry: entropic traps due to variation of channel width are modeled by dead ends, or pockets, attached individually to each site of a one-dimensional chain. This geometry, combined with periodically alternating external driving, leads to a ratchet effect which is very sensitive to particle size, thus enabling particle sorting. A typical behavior is reversal of the current orientation when we change the density of small and big particles. In an optimal situation, the two types of particles move in opposite directions, and particle separation is in principle perfect. We show that in the simplest situation with one type of particles only, this model is exactly soluble. In the general case we use enhanced mean-field approximation as well as direct numerical simulations.
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Affiliation(s)
- Yosyp A Humenyuk
- Institute of Physics, Czech Academy of Sciences, Na Slovance 2, CZ-18221 Praha, Czech Republic
- Institute for Condensed Matter Physics of the National Academy of Sciences of Ukraine, 1 Svientsitskii St, UA-79011 Lviv, Ukraine
| | - Miroslav Kotrla
- Institute of Physics, Czech Academy of Sciences, Na Slovance 2, CZ-18221 Praha, Czech Republic
| | - Karel Netočný
- Institute of Physics, Czech Academy of Sciences, Na Slovance 2, CZ-18221 Praha, Czech Republic
| | - František Slanina
- Institute of Physics, Czech Academy of Sciences, Na Slovance 2, CZ-18221 Praha, Czech Republic
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Abstract
Diffusion of point-like particles in a two-dimensional channel of varying width is studied. The particles are driven by an arbitrary space dependent force. We construct a general recurrence procedure mapping the corresponding two-dimensional advection-diffusion equation onto the longitudinal coordinate x. Unlike the previous specific cases, the presented procedure enables us to find the one-dimensional description of the confined diffusion even for non-conservative (vortex) forces, e.g. caused by flowing solvent dragging the particles. We show that the result is again the generalized Fick-Jacobs equation. Despite of non existing scalar potential in the case of vortex forces, the effective one-dimensional scalar potential, as well as the corresponding quasi-equilibrium and the effective diffusion coefficient [Formula: see text] can be always found.
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Affiliation(s)
- Pavol Kalinay
- Institute of Physics, Slovak Academy of Sciences, Dúbravská cesta 9, 845 11 Bratislava, Slovakia
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Holubec V, Ryabov A, Yaghoubi M, Varga M, Khodaee A, Foulaadvand M, Chvosta P. Thermal Ratchet Effect in Confining Geometries. Entropy 2017; 19:119. [DOI: 10.3390/e19040119] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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Liu F, Jiang L, Tan HM, Yadav A, Biswas P, van der Maarel JRC, Nijhuis CA, van Kan JA. Separation of superparamagnetic particles through ratcheted Brownian motion and periodically switching magnetic fields. Biomicrofluidics 2016; 10:064105. [PMID: 27917252 PMCID: PMC5116023 DOI: 10.1063/1.4967965] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Accepted: 11/04/2016] [Indexed: 06/06/2023]
Abstract
Brownian ratchet based particle separation systems for application in lab on chip devices have drawn interest and are subject to ongoing theoretical and experimental investigations. We demonstrate a compact microfluidic particle separation chip, which implements an extended on-off Brownian ratchet scheme that actively separates and sorts particles using periodically switching magnetic fields, asymmetric sawtooth channel sidewalls, and Brownian motion. The microfluidic chip was made with Polydimethylsiloxane (PDMS) soft lithography of SU-8 molds, which in turn was fabricated using Proton Beam Writing. After bonding of the PDMS chip to a glass substrate through surface activation by oxygen plasma treatment, embedded electromagnets were cofabricated by the injection of InSn metal into electrode channels. This fabrication process enables rapid production of high resolution and high aspect ratio features, which results in parallel electrodes accurately aligned with respect to the separation channel. The PDMS devices were tested with mixtures of 1.51 μm, 2.47 μm, and 2.60 μm superparamagnetic particles suspended in water. Experimental results show that the current device design has potential for separating particles with a size difference around 130 nm. Based on the promising results, we will be working towards extending this design for the separation of cells or biomolecules.
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Affiliation(s)
- Fan Liu
- Department of Physics, National University of Singapore , Singapore 117542
| | - Li Jiang
- Department of Chemistry, National University of Singapore , Singapore 117543
| | - Huei Ming Tan
- Engineering Science Programme, National University of Singapore , Singapore 117576
| | - Ashutosh Yadav
- Department of Physics, National University of Singapore , Singapore 117542
| | - Preetika Biswas
- Department of Physics, National University of Singapore , Singapore 117542
| | | | - Christian A Nijhuis
- Department of Chemistry, National University of Singapore , Singapore 117543
| | - Jeroen A van Kan
- Department of Physics, National University of Singapore , Singapore 117542
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Abstract
Nanoparticles in aqueous solution are subject to collisions with solvent molecules, resulting in random, Brownian motion. By breaking the spatiotemporal symmetry of the system, the motion can be rectified. In nature, Brownian ratchets leverage thermal fluctuations to provide directional motion of proteins and enzymes. In man-made systems, Brownian ratchets have been used for nanoparticle sorting and manipulation. Implementations based on optical traps provide a high degree of tunability along with precise spatiotemporal control. Here, we demonstrate an optical Brownian ratchet based on the near-field traps of an asymmetrically patterned photonic crystal. The system yields over 25 times greater trap stiffness than conventional optical tweezers. Our technique opens up new possibilities for particle manipulation in a microfluidic, lab-on-chip environment.
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Affiliation(s)
- Shao-Hua Wu
- Ming Hsieh Department of Electrical Engineering, Viterbi School of Engineering, University of Southern California , Los Angeles, California 90089, United States
| | - Ningfeng Huang
- Ming Hsieh Department of Electrical Engineering, Viterbi School of Engineering, University of Southern California , Los Angeles, California 90089, United States
| | - Eric Jaquay
- Ming Hsieh Department of Electrical Engineering, Viterbi School of Engineering, University of Southern California , Los Angeles, California 90089, United States
| | - Michelle L Povinelli
- Ming Hsieh Department of Electrical Engineering, Viterbi School of Engineering, University of Southern California , Los Angeles, California 90089, United States
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Abstract
Transport phenomena of interacting particles are of high interest for many applications in biology and mesoscopic systems. Here we present measurements on colloidal particles, which are confined in narrow channels on a substrate and interact with a barrier, which impedes the motion along the channel. The substrate of the particle is tilted in order for the particles to be driven towards the barrier and, if the energy gained by the tilt is large enough, surpass the barrier by thermal activation. We therefore study the influence of this barrier as well as the influence of particle interaction on the particle transport through such systems. All experiments are supported with Brownian dynamics simulations in order to complement the experiments with tests of a large range of parameter space which cannot be accessed in experiments.
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