Active generation and magnetic actuation of microrobotic swarms in bio-fluids

AbstractIn nature, various types of animals will form self-organised large-scale structures. Through designing wireless actuation methods, microrobots can emulate natural swarm behaviours, which have drawn extensive attention due to their great potential in biomedical applications. However, as the prerequisite for their in-vivo applications, whether microrobotic swarms can take effect in bio-fluids with complex components has yet to be fully investigated. In this work, we first categorise magnetic active swarms into three types, and individually investigate the generation and navigation behaviours of two types of the swarms in bio-fluids. The influences of viscosities, ionic strengths and mesh-like structures are studied. A strategy is then proposed to select the optimised swarms in different fluidic environments based on their physical properties, and the results are further validated in various bio-fluids. Moreover, we also realise the swarm generation and navigation in bovine eyeballs, which also validates the proposed prediction in the ex-vivo environment.

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Some comments about observations and image processing of comet 29P/Schwassmann-Wachmann 1

International Astronomical Union Colloquium ◽

10.1017/s0252921100031493 ◽

1999 ◽

Vol 173 ◽

pp. 243-248

Author(s):

D. Kubáček ◽

A. Galád ◽

A. Pravda

Keyword(s):

Image Processing ◽

Large Scale ◽

Harvard College ◽

Oak Ridge ◽

Large Scale Structures ◽

Short Period Comet ◽

Short Period ◽

Scale Structures ◽

Harvard College Observatory ◽

Period Comet

AbstractUnusual short-period comet 29P/Schwassmann-Wachmann 1 inspired many observers to explain its unpredictable outbursts. In this paper large scale structures and features from the inner part of the coma in time periods around outbursts are studied. CCD images were taken at Whipple Observatory, Mt. Hopkins, in 1989 and at Astronomical Observatory, Modra, from 1995 to 1998. Photographic plates of the comet were taken at Harvard College Observatory, Oak Ridge, from 1974 to 1982. The latter were digitized at first to apply the same techniques of image processing for optimizing the visibility of features in the coma during outbursts. Outbursts and coma structures show various shapes.

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Large-Scale Structures in a Compressible Mixing Layer over a Cavity

AIAA Journal ◽

10.2514/1.1825 ◽

2003 ◽

Vol 41 (12) ◽

Author(s):

Jonathan Poggie ◽

Alexander J. Smits

Keyword(s):

Large Scale ◽

Mixing Layer ◽

Compressible Mixing Layer ◽

Large Scale Structures ◽

Scale Structures

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Large-scale structures predicted by linear models of wall-bounded turbulence

Journal of Physics Conference Series ◽

10.1088/1742-6596/1522/1/012006 ◽

2020 ◽

Vol 1522 ◽

pp. 012006

Author(s):

S. Symon ◽

S. J. Illingworth ◽

I. Marusic

Keyword(s):

Large Scale ◽

Linear Models ◽

Large Scale Structures ◽

Scale Structures ◽

Wall Bounded Turbulence

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The organization and control of an evolving interdependent population

Journal of The Royal Society Interface ◽

10.1098/rsif.2015.0044 ◽

2015 ◽

Vol 12 (108) ◽

pp. 20150044 ◽

Cited By ~ 5

Author(s):

Dervis C. Vural ◽

Alexander Isakov ◽

L. Mahadevan

Keyword(s):

Evolutionary Game Theory ◽

Large Scale ◽

Social Evolution ◽

Evolutionary Game ◽

Large Scale Structures ◽

External Perturbations ◽

Emergence Of Cooperation ◽

Scale Structures ◽

And Control ◽

Evolutionarily Stable

Starting with Darwin, biologists have asked how populations evolve from a low fitness state that is evolutionarily stable to a high fitness state that is not. Specifically of interest is the emergence of cooperation and multicellularity where the fitness of individuals often appears in conflict with that of the population. Theories of social evolution and evolutionary game theory have produced a number of fruitful results employing two-state two-body frameworks. In this study, we depart from this tradition and instead consider a multi-player, multi-state evolutionary game, in which the fitness of an agent is determined by its relationship to an arbitrary number of other agents. We show that populations organize themselves in one of four distinct phases of interdependence depending on one parameter, selection strength. Some of these phases involve the formation of specialized large-scale structures. We then describe how the evolution of independence can be manipulated through various external perturbations.

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A Tumbling Magnetic Microrobot System for Biomedical Applications

Micromachines ◽

10.3390/mi11090861 ◽

2020 ◽

Vol 11 (9) ◽

pp. 861

Author(s):

Elizabeth E. Niedert ◽

Chenghao Bi ◽

Georges Adam ◽

Elly Lambert ◽

Luis Solorio ◽

...

Keyword(s):

Ultrasound Imaging ◽

Biomedical Applications ◽

Imaging System ◽

Ex Vivo ◽

Negative Control ◽

Circular Path ◽

Rotational Axis ◽

Significant Difference

A microrobot system comprising an untethered tumbling magnetic microrobot, a two-degree-of-freedom rotating permanent magnet, and an ultrasound imaging system has been developed for in vitro and in vivo biomedical applications. The microrobot tumbles end-over-end in a net forward motion due to applied magnetic torque from the rotating magnet. By turning the rotational axis of the magnet, two-dimensional directional control is possible and the microrobot was steered along various trajectories, including a circular path and P-shaped path. The microrobot is capable of moving over the unstructured terrain within a murine colon in in vitro, in situ, and in vivo conditions, as well as a porcine colon in ex vivo conditions. High-frequency ultrasound imaging allows for real-time determination of the microrobot’s position while it is optically occluded by animal tissue. When coated with a fluorescein payload, the microrobot was shown to release the majority of the payload over a 1-h time period in phosphate-buffered saline. Cytotoxicity tests demonstrated that the microrobot’s constituent materials, SU-8 and polydimethylsiloxane (PDMS), did not show a statistically significant difference in toxicity to murine fibroblasts from the negative control, even when the materials were doped with magnetic neodymium microparticles. The microrobot system’s capabilities make it promising for targeted drug delivery and other in vivo biomedical applications.

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