High-speed propulsion of flexible nanowire motors: Theory and experiments

Pak, On Shun; Gao, Wei; Wang, Joseph; Lauga, Eric

doi:10.1039/c1sm05503h

Cited by 200 publications

(238 citation statements)

References 41 publications

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“…To date, three main approaches have been developed to transport microscopic particles in a viscous fluid using uniform magnetic fields [21], namely, by actuating flexible magnetic tails [12,22], by rotating helical shaped structures [23,24], or by using the close proximity to a bounding wall [25,26]. In the latter case, it is well established that in the Stokes regime the rotational motion of a body close to a surface can be rectified into net translation due to the hydrodynamic interaction with the boundary [27].…”

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confidence: 99%

Colloidal Microworms Propelling via a Cooperative Hydrodynamic Conveyor Belt

et al. 2015

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We study propulsion arising from microscopic colloidal rotors dynamically assembled and driven in a viscous fluid upon application of an elliptically polarized rotating magnetic field. Close to a confining plate, the motion of this self-assembled microscopic worm results from the cooperative flow generated by the spinning particles which act as a hydrodynamic "conveyor belt." Chains of rotors propel faster than individual ones, until reaching a saturation speed at distances where induced-flow additivity vanishes. By combining experiments and theoretical arguments, we elucidate the mechanism of motion and fully characterize the propulsion speed in terms of the field parameters. DOI: 10.1103/PhysRevLett.115.138301 PACS numbers: 82.70.Dd, 87.85.gj Propulsion in viscous fluids plays a key role in many different contexts of biology, physics, and chemistry. From a fundamental perspective, the transport of microscopic objects in a liquid medium poses the appealing challenge to find an adequate swimming strategy due to the negligible role of inertial force compared to viscous one. At low Reynolds number the Navier-Stokes equations become time reversible [1], and any strategy based on reciprocal motion, i.e., a motion composed by symmetric backward and forward displacements, will fail to produce net propulsion [2].Facing this challenge, the last few years have witnessed the theoretical propositions of several suitable geometries and procedures to propel micromachines in viscous fluids [3][4][5][6][7][8][9]. Parallel advances in miniaturization have led to the generation of new classes of chemically powered [10,11] or externally actuated [12][13][14][15] prototypes with exciting applications in emerging fields such as microsurgery [16,17] or lab-on-a-chip technology [18,19].In contrast to reaction driven microswimmers, actuated magnetic micropropellers do not present the autonomous behavior that distinguishes force-and torque-free motion of biological organisms [20], but instead avoid efficiency reduction due to fuel shortage or directional randomization. To date, three main approaches have been developed to transport microscopic particles in a viscous fluid using uniform magnetic fields [21], namely, by actuating flexible magnetic tails [12,22], by rotating helical shaped structures [23,24], or by using the close proximity to a bounding wall [25,26]. In the latter case, it is well established that in the Stokes regime the rotational motion of a body close to a surface can be rectified into net translation due to the hydrodynamic interaction with the boundary [27]. Surface rotors are optimal to work in confined geometries such as microfluidic channels or biological networks characterized by narrow pores.In this Letter we show that an ensemble of rotors dynamically self-assembled via attractive dipolar interactions can be propelled by a hydrodynamic "conveyor-belt" effect generated by the cooperative flow of the spinning particles close to a surface. Recent theoretical works [28][29][30] have addressed the rich dynamic...

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confidence: 99%

Colloidal Microworms Propelling via a Cooperative Hydrodynamic Conveyor Belt

et al. 2015

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“…The shape patterns of the flexible filament, propulsive force and fluid structures are computed and the results are compared with the theoretical and experimental results (Pak et al, 2011;Taylor, 1951). In simulation, various Reynolds numbers from Re ¼ 0.15 up to Re¼ 5.1 are used.…”

Section: Introductionmentioning

confidence: 99%

“…For example, measured the shape pattern and proposed bending moduli for the flagellum. Yu et al (2006) measured the propulsive force for the swimming flagellum, Pak et al (2011) designed a flexible nanowire motor to give a high speed propulsion for the flagellum. All the above work are based on the Stokes equation where inertia is ignored and the Reynolds number is zero.…”

Section: Introductionmentioning

confidence: 99%

Simulation of swimming of a flexible filament using the generalized lattice-spring lattice-Boltzmann method

Wu¹,

Guo²,

He³

et al. 2014

Journal of Theoretical Biology

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We introduced a generalized lattice-spring lattice-Boltzmann model (GLLM) for numerical simulation of flexible bodies in fluids. Validation of GLLM is conducted by comparing our results with existing theoretical and experimental results. Swimming of a flexible filament driven by its header with a harmonic function is simulated at Reynolds numbers ranged 0.15-5.1. The wave patterns of the filament are consistent with the theory of elastohydrodynamics at low Reynolds number and the wave wriggles increase as the Reynolds number increases. Intensity of vortices and propulsive force increases as Reynolds number increases. a r t i c l e i n f o

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“…[24][25][26] Highly efficient exible magnetic nanowire swimmers have been prepared recently by a simple membrane-template electrodeposition route. [27][28][29] The resulting magnetic nanowire swimmers have already been used successfully for the directed delivery of drug-loaded microparticles to HeLa cancer cells in the cell culture media. 30 In the following sections we will illustrate biocatalytically induced growth of distinct helical Au microstructures during the magnetically powered movement of GOx-functionalized exible nanowire motors.…”

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Nanomotor-based biocatalytic patterning of helical metal microstructures

et al. 2013

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A new nanomotor-based surface-patterning technique based on the movement of a magnetically powered enzyme-functionalized flexible nanowire swimmer offers the ability to create complex helical metal microstructures.There has been a considerable recent interest in synthetic nanomotors, based on different propulsion mechanisms, owing to their great promise for a wide range of future technological applications. 1-10 Self-propelled nano/microscale machines have demonstrated considerable potential for performing diverse operations and important tasks, ranging from isolation of biomaterials, 11 nanotool-based drilling, 12 delivery of therapeutic payloads, 13 to environmental remediation. 14 This communication reports on the use of exible magnetic nanowire swimmers for biocatalytic patterning of complex surface microstructures. The preparation of well-dened surface micro/ nanostructures represents an important goal of microfabrication. Tip-based scanning-probe (SP) techniques have been extremely useful for depositing chemical or biological materials onto at substrates. 15 Such tip-based SP fabrication methods commonly rely on the controlled movement of a functionalized tip along predetermined paths for a localized surface modication. Willner et al. [16][17][18][19] have demonstrated the successful combination of Dip-PenNanolithography (DPN) and biocatalytic inks for generating Au or Ag nanowires in connection with the deposition of glucose oxidase (GOx) or alkaline-phosphatase lines, respectively. However, patterning of three-dimensional structures with high topological complexity of a helix represents a major fabrication challenge even with advanced lithographic techniques such as DPN. [16][17][18][19] Recent advances in nanomotors have facilitated the realization of the new nanomotor-based direct biocatalytic patterning method.These include the ability to navigate the motors along predetermined complex paths, to control and regulate their speed, to functionalize them with different biological or chemical entities, and to move them rapidly over large areas. 20,21 Previous studies reported that HRP-functionalized catalytic nanowire motors can be used for writing localized polymeric lines. 22 However, the limited propulsion of these catalytic nanomotors in high-ionic strength environments and the peroxide-fuel requirement hinder the applications of these nanomotors. 23 Similar to different tip-based SP fabrication techniques, 15 nanomotors based on different propulsion and guidance mechanisms could be employed for creating a variety of surface microstructures. Various microstructures, made of different materials (polymers, metals, etc.), can thus be fabricated on conducting and insulating substrates based on a judicious choice of the reactants and the specic reaction involved. In view of the 'large' (submicrometer) size of catalytic nanomotors, compared to common SP tips, the new nanomotor 'writing' method is currently limited to the creation of microscale surface features.This study illustrates for the rst time th...

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High-speed propulsion of flexible nanowire motors: Theory and experiments

Cited by 200 publications

References 41 publications

Colloidal Microworms Propelling via a Cooperative Hydrodynamic Conveyor Belt

Colloidal Microworms Propelling via a Cooperative Hydrodynamic Conveyor Belt

Simulation of swimming of a flexible filament using the generalized lattice-spring lattice-Boltzmann method

Nanomotor-based biocatalytic patterning of helical metal microstructures

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