Topographical pathways guide chemical microswimmers

Simmchen, Juliane; Katuri, Jaideep; Uspal, William E.; Popescu, M. N.; Tasinkevych, M.; Sánchez, Samuel

doi:10.1038/ncomms10598

Cited by 367 publications

(503 citation statements)

References 40 publications

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“…A similar strategy could be proposed by synthetic chemically powered motors 10. Alternatively, external fields8, 11, 12, 13, 14, 15 and interactions with surfaces16, 17, 18, 19 have also been proposed as ways to control motor motion. When many motors interact with each other, phenomena such as dynamic clustering, swarming and active phase segregation are observed 20, 21, 22, 23, 24.…”

Section: Introductionmentioning

confidence: 99%

Chemically Propelled Motors Navigate Chemical Patterns

Chen

Kapral

2018

Advanced Science

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Very small synthetic motors that use chemical reactions to drive their motion are being studied widely because of their potential applications, which often involve active transport and dynamics on nanoscales. Like biological molecular machines, they must be able to perform their tasks in complex, highly fluctuating environments that can form chemical patterns with diverse structures. Motors in such systems can actively assemble into dynamic clusters and other unique nonequilibrium states. It is shown how chemical patterns with small characteristic dimensions may be utilized to suppress rotational Brownian motions of motors and guide them to move along prescribed paths, properties that can be exploited in applications. In systems with larger pattern length scales, domains can serve as catch basins for motors through chemotactic effects. The resulting collective motor dynamics in such confining domains can be used to explore new aspects of active particle collective dynamics or promote specific types of active self‐assembly. More generally, when chemically self‐propelled motors operate in far‐from‐equilibrium active chemical media the variety of possible phenomena and the scope of their potential applications are substantially increased.

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Section: Introductionmentioning

confidence: 99%

Chemically Propelled Motors Navigate Chemical Patterns

Chen

Kapral

2018

Advanced Science

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“…Likewise, controlling the state of stress or strain of semiconductor particles is challenging in unconstrained nucleation-and-growth synthesis methods. However, Janus particles of silicon−germanium (SiGe) could potentially find applications as microswimmers or nanoswimmers owing to asymmetric absorption properties (8), as well as in infrared photodetectors or solar cells for increased infrared absorption (9). Stressed silicon particles, on the other hand, could be used for bandgap tunability in photonic or optoelectronic devices (10)(11)(12).…”

mentioning

confidence: 99%

Confined in-fiber solidification and structural control of silicon and silicon−germanium microparticles

Gumennik

Levy

Grena

et al. 2017

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

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Crystallization of microdroplets of molten alloys could, in principle, present a number of possible morphological outcomes, depending on the symmetry of the propagating solidification front and its velocity, such as axial or spherically symmetric species segregation. However, because of thermal or constitutional supercooling, resulting droplets often only display dendritic morphologies. Here we report on the crystallization of alloyed droplets of controlled micrometer dimensions comprising silicon and germanium, leading to a number of surprising outcomes. We first produce an array of silicon−germanium particles embedded in silica, through capillary breakup of an alloy-core silica-cladding fiber. Heating and subsequent controlled cooling of individual particles with a two-wavelength laser setup allows us to realize two different morphologies, the first being a silicon−germanium compositionally segregated Janus particle oriented with respect to the illumination axis and the second being a sphere made of dendrites of germanium in silicon. Gigapascal-level compressive stresses are measured within pure silicon solidified in silica as a direct consequence of volume-constrained solidification of a material undergoing anomalous expansion. The ability to generate microspheres with controlled morphology and unusual stresses could pave the way toward advanced integrated in-fiber electronic or optoelectronic devices. multimaterial fibers | microparticles | confined solidification | silicon−germanium spheres | stressed silicon C ontrolling the microstructure or state of stress of microparticles and nanoparticles is often key to attaining the desired properties for a specific application (1-5); however, the ability to do so is strongly limited by the synthesis method. For instance, nonspherically symmetric distributions of inorganic materials are difficult to achieve from bottom-up approaches (4-7). Likewise, controlling the state of stress or strain of semiconductor particles is challenging in unconstrained nucleation-and-growth synthesis methods. However, Janus particles of silicon−germanium (SiGe) could potentially find applications as microswimmers or nanoswimmers owing to asymmetric absorption properties (8), as well as in infrared photodetectors or solar cells for increased infrared absorption (9). Stressed silicon particles, on the other hand, could be used for bandgap tunability in photonic or optoelectronic devices (10-12).In the past few years, thermally drawn multimaterial fibers have emerged as a unique platform for top-down scalable fabrication of microparticles to nanoparticles over a broad range of materials, through controlled in-fiber capillary breakup of the fiber components (13-15). In the case of polymers or chalcogenide glasses, structural control of the particle can be achieved by constructing complex cores at the preform level, which is later broken up in the fiber state to form structured particles (13). However, in the case of traditional semiconductor materials such as silicon and germanium, the same...

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“…For instance, active particles can exhibit taxis: under certain conditions, they can reliably reorient and migrate in response to cues (such as gravitational fields [15,77], the topography of bounding surfaces [73,74], externally imposed flows [78], or fluid interface-response flows [79]) in their environment. Here we shall consider the possible effects of gravity and external flow.…”

Section: Self-diffusiophoresis Under External Fields or Flowsmentioning

confidence: 99%

“…Experimental observations of such surface-bounded states for a few types of chemically active particles and various confining geometries have been reported recently [72][73][74]. (Note that in these studies the analysis is more involved due to the fact that the force and the torque due to gravity are relevant and thus have to be included in the corresponding force and torque balance (Eq.…”

mentioning

confidence: 99%

Self-diffusiophoresis of chemically active colloids

Popescu

Uspal

Dietrich

2016

Eur. Phys. J. Spec. Top.

Self Cite

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Abstract. Chemically active colloids locally change the chemical composition of their solvent via catalytic reactions which occur on parts of their surface. They achieve motility by converting the released chemical free energy into mechanical work through various mechanisms, such as phoresis. Here we discuss the theoretical aspects of self-diffusiophoresis, which -despite being one of the simplest motility mechanisms -captures many of the general features characterizing self-phoresis, such as self-generated and maintained hydrodynamic flows "driven" by surface activity induced inhomogeneities in solution. By studying simple examples, which provide physical insight, we highlight the complex phenomenology which can emerge from self-diffusiophoresis.

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Topographical pathways guide chemical microswimmers

Cited by 367 publications

References 40 publications

Chemically Propelled Motors Navigate Chemical Patterns

Chemically Propelled Motors Navigate Chemical Patterns

Confined in-fiber solidification and structural control of silicon and silicon−germanium microparticles

Self-diffusiophoresis of chemically active colloids

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