Understanding the Efficiency of Autonomous Nano- and Microscale Motors

Wang, Wei; Chiang, Tso Yi; Velegol, Darrell; Mallouk, Thomas E.

doi:10.1021/ja405135f

Cited by 232 publications

(282 citation statements)

References 65 publications

(127 reference statements)

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“…In order to do so, we used the so-called swimmer efficiency [34,36,37], which is the swimmer's hydrodyamic power output over the total enthalpy produced by the reaction. We find that the most efficient way to self-propel is to have the surface reactions take place in an isolated spot on the surface of the pole in self-diffusiophoresis.…”

Section: Discussion and Outlookmentioning

confidence: 99%

“…The concept of the efficiency of swimming has since been investigated by Sabass and Seifert, who showed that nanoparticles are far more efficient at self-propulsion than micron sized colloids [35] and examined this quantity the context of self-electrophoresis [36]. More recently, Wang et al [37] performed an analysis of the efficiency of various types of swimmers.…”

Section: Introductionmentioning

confidence: 99%

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The efficiency of self-phoretic propulsion mechanisms with surface reaction heterogeneity

Kreissl

Holm

Graaf

2016

The Journal of Chemical Physics

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We consider the efficiency of self-phoretic colloidal particles (swimmers) as a function of the heterogeneity in the surface reaction rate. The set of fluid, species, and electrostatic continuity equations is solved analytically using a linearization and numerically using a finite-element method. To compare spherical swimmers of different size and with heterogeneous catalytic conversion rates, a 'swimmer efficiency' functional η is introduced. It is proven, that in order to obtain maximum swimmer efficiency the reactivity has to be localized at the pole(s). Our results also shed light on the sensitivity of the propulsion speed to details of the surface reactivity, a property that is notoriously hard to measure. This insight can be utilized in the design of new self-phoretic swimmers.

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Section: Discussion and Outlookmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The efficiency of self-phoretic propulsion mechanisms with surface reaction heterogeneity

Kreissl

Holm

Graaf

2016

The Journal of Chemical Physics

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“…The ion distribution and electrical charges around the Au-Pt nanomotors operating by self-electrophoresis were simulated by using a finite element model. The simulation was carried out with the COMSOL multiphysics package (47). Details of this simulation model can be found in SI Text.…”

Section: Methodsmentioning

confidence: 99%

“…The electric field distribution around the motors was simulated by using the COMSOL multiphysics package (see ref. 47 for modeling details). Then, an electrophoretic velocity profile as a function of the distance between the tracer particle and the motor was calculated based on the electric field distribution (Fig.…”

Section: Significancementioning

confidence: 99%

Catalytically powered dynamic assembly of rod-shaped nanomotors and passive tracer particles

Wang

Duan

Sen

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

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183

173

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Nano-and microscale motors powered by catalytic reactions exhibit collective behavior such as swarming, predator-prey interactions, and chemotaxis that resemble those of biological microorganisms. A quantitative understanding of the catalytically generated forces between particles that lead to these behaviors has so far been lacking. Observations and numerical simulations of pairwise interactions between gold-platinum nanorods in hydrogen peroxide solutions show that attractive and repulsive interactions arise from the catalytically generated electric field. Electrokinetic effects drive the assembly of staggered doublets and triplets of nanorods that are moving in the same direction. None of these behaviors are observed with nanorods composed of a single metal. The motors also collect tracer microparticles at their head or tail, depending on the charge of the particles, actively assembling them into close-packed rafts and aggregates of rafts. These motor-tracer particle interactions can also be understood in terms of the catalytically generated electric field around the ends of the nanorod motors.dynamic interactions | self-assembly | colloidal transport T he dynamic interactions between moving objects, in particular their response to external stimuli and their communication with each other, govern their collective behavior on many length scales. Schooling of fish and flocking of birds are good examples of emergent phenomena that are orchestrated by communication between individuals in a large group. In these systems, macroscale organization is typically driven by nearest neighbor interactions that follow simple rules. To reach the level of organization seen in such living assemblies, fast and precise (in terms of distances, angles, and velocities) communication and control are required from the members. It is now straightforward to create computational models from which such dynamic structures emerge, but artificial systems that mimic behaviors as complicated as fish schooling have very rarely been realized experimentally in macroscopic engineered systems (1). On the other hand, self-assembly at the nano-and molecular levels already demonstrates a certain level of complexity and has furthered our understanding of dynamic interactions at small scales (2, 3).There are already many examples of particle assembly driven by local forces or externally applied fields. Externally applied light, magnetic, electric, and acoustic fields can drive symmetric particles into ordered arrays (4-7). Colloidal Janus particles selfassemble into complex structures by various mechanisms (8-12). However, in these examples the particle aggregates hardly approach the complexity of assemblies of living organisms; the interactions are passive responses to local forces and external fields with very limited interparticle communication or active response to the behavior of nearest neighbors.Interactions between active particles, on the other hand, can more closely mimic those of living organisms (13-17). Powered particles generate signals, t...

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“…Leveraging the high precision in the alignment, the linear dependence of speed on the inverse of size of nanomotors (1/l) down to submicrometers, is experimentally determined, confirming previous theoretical predictions. 14 Finally, the manipulation of catalytic nanomotors by E-fields is demonstrated for two applications: the dynamic loading, transport, and unloading of micro-targets to pre-patterned microdocks; and assembling and integration of a catalytic nanomotor on a rotary NEMS to power its continuous operation. …”

Section: Introductionmentioning

confidence: 99%

Electric-Field-Guided Precision Manipulation of Catalytic Nanomotors for Cargo Delivery and Powering Nanoelectromechanical Devices

et al. 2018

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ABSTRACT:We report a controllable and precision approach in manipulating catalytic nanomotors by strategically applied electric (E-) fields in three dimensions (3-D). With the high controllability, the catalytic nanomotors have demonstrated new versatility in capturing, delivering, and releasing of cargos to designated locations as well as in-situ integration with nanomechanical devices (NEMS) to chemically power the actuation. With combined AC and DC E-fields, catalytic nanomotors can be accurately aligned by the AC E-fields and instantly change their speeds by the DC E-fields. Within the 3-D orthogonal microelectrode sets, the in-plane transport of catalytic nanomotors can be swiftly turned on and off, and these catalytic nanomotors can also move in the vertical direction. The interplaying nanoforces that govern the propulsion and alignment are investigated. The modeling of catalytic nanomotors proposed in previous works has been confirmed quantitatively here. Finally, the prowess of the precision manipulation of catalytic nanomotors by E-fields is demonstrated in two applications: the capture, transport, and release of cargos to pre-patterned microdocks, and the assembly of catalytic nanomotors on NEMS to power the continuous rotation. The innovative concepts and approaches reported in this work could further advance ideal applications of catalytic nanomotors, e.g. for assembling and powering nanomachines, nanorobots, and complex NEMS devices.

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Understanding the Efficiency of Autonomous Nano- and Microscale Motors

Cited by 232 publications

References 65 publications

The efficiency of self-phoretic propulsion mechanisms with surface reaction heterogeneity

The efficiency of self-phoretic propulsion mechanisms with surface reaction heterogeneity

Catalytically powered dynamic assembly of rod-shaped nanomotors and passive tracer particles

Electric-Field-Guided Precision Manipulation of Catalytic Nanomotors for Cargo Delivery and Powering Nanoelectromechanical Devices

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