Localized Bioconvection of<i>Euglena</i>Caused by Phototaxis in the Lateral Direction

Suematsu, Nobuhiko J.; Awazu, Akinori; Izumi, Shin-ichi; Noda, Shinshi; Nakata, Satoshi; Nishimori, Hiraku

doi:10.1143/jpsj.80.064003

Cited by 30 publications

(24 citation statements)

References 26 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For instance, microorganisms can react in a chemotactic way when they detect chemicals that indicate nutrition, or they use chemicals for communication between each other without physical contact [368,400,607,[611][612][613][614]. Further examples concern the reaction to light (phototaxis) [370,615,616], gravitation (gravitaxis) [617,618], flow fields (rheotaxis) [619], adhesion gradients (haptotaxis) [620,621], and other external stimuli. Nevertheless, aspects of the collective behavior can often be described by simple particle descriptions in the form of extended Vicsek approaches [373,416] or by minimum continuum models [489,495,507,622].…”

Section: Collective Behavior Of Animalsmentioning

confidence: 99%

Tuned, driven, and active soft matter

2015

View full text Add to dashboard Cite

One characteristic feature of soft matter systems is their strong response to external stimuli. As a consequence they are comparatively easily driven out of their ground state and out of equilibrium, which leads to many of their fascinating properties. Here, we review illustrative examples. This review is structured by an increasing distance from the equilibrium ground state. On each level, examples of increasing degree of complexity are considered. In detail, we first consider systems that are quasi-statically tuned or switched to a new state by applying external fields. These are common liquid crystals, liquid crystalline elastomers, or ferrogels and magnetic elastomers. Next, we concentrate on systems steadily driven from outside e.g. by an imposed flow field. In our case, we review the reaction of nematic liquid crystals, of bulk-filling periodically modulated structures such as block copolymers, and of localized vesicular objects to an imposed shear flow. Finally, we focus on systems that are "active" and "self-driven". Here our range spans from idealized self-propelled point particles, via sterically interacting particles like granular hoppers, via microswimmers such as self-phoretically driven artificial Janus particles or biological microorganisms, via deformable self-propelled particles like droplets, up to the collective behavior of insects, fish, and birds. As we emphasize, similarities emerge in the features and behavior of systems that at first glance may not necessarily appear related. We thus hope that our overview will further stimulate the search for basic unifying principles underlying the physics of these soft materials out of their equilibrium ground state.Comment: 84 pages, 30 figure

show abstract

Section: Collective Behavior Of Animalsmentioning

confidence: 99%

Tuned, driven, and active soft matter

2015

View full text Add to dashboard Cite

show abstract

“…[1][2][3][4][5][6][7][8][9] Controlled swarm motion may be employed to generate flows in lab-onchip devices in conjunction with digital microfluidics, [1][2][3][4][5][10][11][12] on-chip computation as previously explored with droplet logic and neural computation, 7,13 cargo delivery, 6,[14][15][16] and for selfassembly of nano-and microdevices. 8,10,15,[17][18][19][20] Algorithms for efficient control and programming of such swarms have been extensively studied via theory 20,21 and experiment in both synthetic 22 and natural systems, from motor proteins and filaments 23,24 to single-celled organisms 2,8,25,26 to insects 27 to macroscopic robots.…”

Section: Introductionmentioning

confidence: 99%

Device and programming abstractions for spatiotemporal control of active micro-particle swarms

et al. 2017

View full text Add to dashboard Cite

We present a hardware setup and a set of executable commands for spatiotemporal programming and interactive control of a swarm of self-propelled microscopic agents inside a microfluidic chip. In particular, local and global spatiotemporal light stimuli are used to direct the motion of ensembles of Euglena gracilis, a unicellular phototactic organism. We develop three levels of programming abstractions (stimulus space, swarm space, and system space) to create a scripting language for directing swarms. We then implement a multi-level proof-of-concept biotic game using these commands to demonstrate their utility. These device and programming concepts will enhance our capabilities for manipulating natural and synthetic swarms, with future applications for on-chip processing, diagnostics, education, and research on collective behaviors.

show abstract

“…However, although bioconvection is an appealing mechanism to generate or enhance mixing in biological suspensions [12,13], a major challenge in bioreactor technologies, but also to prevent biofouling and even to harvest micro-organisms [14], its control remains elusive. Indeed, bioconvection studies so far have been essentially restricted to pattern selection, appearing spontaneously in concentrated layers, where a vertical (in the direction of gravity) cell concentration gradient develops as a result of the upward-swimming induced by negative gravitaxis [15][16][17][18], oxygen consumption [19][20][21] or a combination of several fields [22][23][24][25][26][27][28][29].…”

mentioning

confidence: 99%

Light-controlled flows in active fluids

2016

View full text Add to dashboard Cite

Many photosynthetic microorganisms are able to detect light and move toward optimal intensities. This ability, known as phototaxis, plays a major role in ecology by affecting natural phytoplankton mass transfers and has important applications in bioreactor and artificial microswimmers technologies. Here we show that this property can be exploited to generate macroscopic fluid flows using a localized light source directed toward shallow suspensions of phototactic microorganisms. Within the intensity range of positive phototaxis, algae accumulate beneath the excitation light where collective effects lead to the emergence of radially symmetric convective flows. These flows can thus be used as hydrodynamic tweezers to manipulate small floating objects. At high cell density and layer depth, we uncover a new kind of instability wherein the viscous torque exerted by self-generated fluid flows on the swimmers induces the formation of traveling waves. A model coupling fluid flow, cell concentration and orientation finely reproduces the experimental data.

show abstract

Localized Bioconvection ofEuglenaCaused by Phototaxis in the Lateral Direction

Cited by 30 publications

References 26 publications

Tuned, driven, and active soft matter

Tuned, driven, and active soft matter

Device and programming abstractions for spatiotemporal control of active micro-particle swarms

Light-controlled flows in active fluids

Contact Info

Product

Resources

About