Dynamics of confined microswimmers inside a droplet: From microactivity to macromovement

In this thesis we investigate three experiments where bacterial suspensions are encapsulated in droplets. The aim of these experiments is to understand how the microactivity at the local scale, when bacteria organize collectively, can create a macromovement at the containing droplet scale, which is...

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Detalles Bibliográficos
Autor: Ramos Peroni, Gabriel Patricio
Tipo de recurso: tesis doctoral
Estado:Versión publicada
Fecha de publicación:2020
País:Chile
OAI Identifier:oai:repositorio.anid.cl:10533/246251
Acceso en línea:https://hdl.handle.net/10533/246251
Access Level:acceso abierto
Palabra clave:Ciencias Naturales
Ciencias Físicas
Otras Especialidades de la Física
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dc.title.es_CL.fl_str_mv Dynamics of confined microswimmers inside a droplet: From microactivity to macromovement
Dimámica de micronadadores confinados en una gota: Desde la microactividad al macromovmiento
title Dynamics of confined microswimmers inside a droplet: From microactivity to macromovement
spellingShingle Dynamics of confined microswimmers inside a droplet: From microactivity to macromovement
Ramos Peroni, Gabriel Patricio
Ciencias Naturales
Ciencias Físicas
Otras Especialidades de la Física
title_short Dynamics of confined microswimmers inside a droplet: From microactivity to macromovement
title_full Dynamics of confined microswimmers inside a droplet: From microactivity to macromovement
title_fullStr Dynamics of confined microswimmers inside a droplet: From microactivity to macromovement
title_full_unstemmed Dynamics of confined microswimmers inside a droplet: From microactivity to macromovement
title_sort Dynamics of confined microswimmers inside a droplet: From microactivity to macromovement
dc.creator.none.fl_str_mv Ramos Peroni, Gabriel Patricio
author Ramos Peroni, Gabriel Patricio
author_facet Ramos Peroni, Gabriel Patricio
author_role author
dc.contributor.advisor.none.fl_str_mv Cordero Garayar, María Luisa
Soto Bertrán, Rodrigo
dc.contributor.institution.es_CL.fl_str_mv UNIVERSIDAD DE CHILE
dc.subject.oecd1n.es_CL.fl_str_mv Ciencias Naturales
topic Ciencias Naturales
Ciencias Físicas
Otras Especialidades de la Física
dc.subject.oecd2n.es_CL.fl_str_mv Ciencias Físicas
dc.subject.oecd3n.es_CL.fl_str_mv Otras Especialidades de la Física
description In this thesis we investigate three experiments where bacterial suspensions are encapsulated in droplets. The aim of these experiments is to understand how the microactivity at the local scale, when bacteria organize collectively, can create a macromovement at the containing droplet scale, which is about 100 times the size of a bacterium. In other words, how we can extract useful work from these encapsulated bacterial suspensions. First, we confine a dense suspension of motile Escherichia coli inside a spherical droplet in a water-in-oil emulsion, creating a "bacterially" propelled droplet. We show that droplets move in a persistent random walk, with a persistence time τ ~ 0.3 s, a long-time diffusion coefficient D ~ 0.5 μm2/s, and an average instantaneous speed V ~ 1.5 μm/s when the bacterial suspension is at the maximum studied concentration. Several droplets are analyzed, varying the drop radius and bacterial concentration. We show that the persistence time, diffusion coefficient and average speed increase with the bacterial concentration inside the drop, but are largely independent of the droplet size. By measuring the turbulent-like motion of the bacteria inside the drop, we demonstrate that the mean velocity of the bacteria near the bottom of the drop, which is separated from a glass substrate by a thin lubrication oil film, is antiparallel to the instantaneous velocity of the drop. This suggests that the driving mechanism is a slippery rolling of the drop over the substrate, caused by the collective motion of the bacteria. Our results show that microscopic organisms can transfer useful mechanical energy to their confining environment, opening the way to the assembly of mesoscopic motors composed of microswimmers. In a second experiment, we show that under the application of a constant magnetic field, motile magnetotactic bacteria confined in water-in-oil droplets self-assemble into a rotary motor exerting a torque on the external oil phase. A collective motion in the form of a large-scale vortex, reversable by inverting the field direction, builds-up in the droplet with a vorticity perpendicular to the magnetic field. We study this collective organization at different concentrations, magnetic fields and droplets radii and reveal the formation of two torque-generating areas close to the droplet interface. We characterize quantitatively the mechanical energy extractable from this new biological and self-assembled motor. Finally, we study a bacterial suspension of E.coli encapsulated in a double emulsion, where an oil droplet gets trapped inside a water-in-oil emulsion. We show that the inner oil droplet performs a persistent random walk in the horizontal plane with a persistence time τ ~ 0.3 s. The diffusion coefficient in the horizontal plane depends inversely on the inner droplet radius, and we compare it with the thermal diffusion coefficient. It allow us to compute an active temperature, which has a value of 2.7×10^4 K, two orders of magnitude larger than room temperature, consistent with the experiment of bacterially propelled droplets and previous works. The vertical plane was also studied, revealing that the diffusion coefficient in the vertical axis is smaller than in the horizontal axis, due to the geometric trapping.
publishDate 2020
dc.date.accessioned.none.fl_str_mv 2020-09-21T14:12:18Z
2022-08-16T21:20:54Z
dc.date.available.none.fl_str_mv 2020-09-21T14:12:18Z
2022-08-16T21:20:54Z
dc.date.issued.es_CL.fl_str_mv 2020
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identifier_str_mv 21150648
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spelling UNIVERSIDAD DE CHILERamos Peroni, Gabriel Patricio2020https://hdl.handle.net/10533/246251http://purl.org/coar/access_right/c_abf2Otras Especialidades de la FísicaCiencias FísicasCiencias NaturalesDynamics of confined microswimmers inside a droplet: From microactivity to macromovementCordero Garayar, María LuisaSoto Bertrán, RodrigoUNIVERSIDAD DE CHILEChileRamos Peroni, Gabriel Patricio2020-09-21T14:12:18Z2022-08-16T21:20:54Z2020-09-21T14:12:18Z2022-08-16T21:20:54Z2020In this thesis we investigate three experiments where bacterial suspensions are encapsulated in droplets. The aim of these experiments is to understand how the microactivity at the local scale, when bacteria organize collectively, can create a macromovement at the containing droplet scale, which is about 100 times the size of a bacterium. In other words, how we can extract useful work from these encapsulated bacterial suspensions. First, we confine a dense suspension of motile Escherichia coli inside a spherical droplet in a water-in-oil emulsion, creating a "bacterially" propelled droplet. We show that droplets move in a persistent random walk, with a persistence time τ ~ 0.3 s, a long-time diffusion coefficient D ~ 0.5 μm2/s, and an average instantaneous speed V ~ 1.5 μm/s when the bacterial suspension is at the maximum studied concentration. Several droplets are analyzed, varying the drop radius and bacterial concentration. We show that the persistence time, diffusion coefficient and average speed increase with the bacterial concentration inside the drop, but are largely independent of the droplet size. By measuring the turbulent-like motion of the bacteria inside the drop, we demonstrate that the mean velocity of the bacteria near the bottom of the drop, which is separated from a glass substrate by a thin lubrication oil film, is antiparallel to the instantaneous velocity of the drop. This suggests that the driving mechanism is a slippery rolling of the drop over the substrate, caused by the collective motion of the bacteria. Our results show that microscopic organisms can transfer useful mechanical energy to their confining environment, opening the way to the assembly of mesoscopic motors composed of microswimmers. In a second experiment, we show that under the application of a constant magnetic field, motile magnetotactic bacteria confined in water-in-oil droplets self-assemble into a rotary motor exerting a torque on the external oil phase. A collective motion in the form of a large-scale vortex, reversable by inverting the field direction, builds-up in the droplet with a vorticity perpendicular to the magnetic field. We study this collective organization at different concentrations, magnetic fields and droplets radii and reveal the formation of two torque-generating areas close to the droplet interface. We characterize quantitatively the mechanical energy extractable from this new biological and self-assembled motor. Finally, we study a bacterial suspension of E.coli encapsulated in a double emulsion, where an oil droplet gets trapped inside a water-in-oil emulsion. We show that the inner oil droplet performs a persistent random walk in the horizontal plane with a persistence time τ ~ 0.3 s. The diffusion coefficient in the horizontal plane depends inversely on the inner droplet radius, and we compare it with the thermal diffusion coefficient. It allow us to compute an active temperature, which has a value of 2.7×10^4 K, two orders of magnitude larger than room temperature, consistent with the experiment of bacterially propelled droplets and previous works. The vertical plane was also studied, revealing that the diffusion coefficient in the vertical axis is smaller than in the horizontal axis, due to the geometric trapping.En esta tesis investigamos tres experimentos en los que confinamos suspensiones bacterianas al interior de microgotas. El objetivo de estos experimentos es entender cómo la microactividad a escala local, cuando las bacterias se organizan colectivamente, es capaz de crear macromovimientos a escalas del tamaño de la gota confinante, la cual es cerca de 100 veces el tamaño de una bacteria. En otras palabras, cómo podemos extraer trabajo útil a partir de suspensiones confinadas. Primero, confinamos una suspensión de Escherichia coli dentro de gotas en una emulsión agua-aceite, creando una gota propulsada por bacterias. Mostramos que las gotas realizan un movimiento aleatorio persistente, con tiempo de persistencia τ ~ 0.3 s, coeficiente de difusión a tiempos largos D ~ 0.5 μm2/s, y rapidez instantánea promedio V ~ 1.5 μm/s a la máxima concentración bacteriana estudiada. Variamos el radio de la gota y la concentración bacteriana, mostrando que el tiempo de persistencia, coeficiente de difusión y rapidez promedio aumentan con la concentración de bacterias, pero son independientes del radio de la gota. Por último, demostramos que la velocidad promedio de las bacterias en el fondo de la gota, el cual está separado del sustrato de vidrio por una delgada película de lubricación de aceite, es antiparalela a la velocidad instantánea de la gota. Esto sugiere que el mecanismo de desplazamiento es una rotación con deslizamiento de la gota sobre el sustrato, causado por el movimiento colectivo de las bacterias. Nuestros resultados muestran que organismos microscópicos pueden trasferir energía mecánica útil a su entorno, abriendo la posibilidad de generar motores mesoscópicos compuestos de micronadadores. En un segundo experimento, mostramos que bajo la aplicación de un campo magnético constante, bacterias magnetotácticas confinadas en una emulsión agua-aceite se autoensamblan en un motor rotatorio ejerciendo un torque sobre la fase oleosa externa. Un movimiento colectivo en la forma de un vórtice de gran escala, reversible al invertir la dirección del campo magnético, se genera al interior de la gota con una vorticidad perpendicular al campo magnético. Estudiamos este movimiento colectivo a diferentes concentraciones de bacterias, campos magnéticos y radios de gota, revelando la formación de dos áreas generadoras de torque cerca de la interfaz. Caracterizamos cuantitativamente la energía mecánica extraíble de este nuevo motor biológico autoensamblado. Finalmente, estudiamos una suspensión bacteriana de E.coli confinada en una doble emulsión, donde una gota de aceite queda atrapada al interior de una emulsión agua-aceite. Mostramos que la gota interior de aceite realiza un movimiento aleatorio persistente en el plano horizontal con un tiempo de persistencia de τ ~ 0.3 s. El coeficiente de difusión en el plano horizontal depende inversamente del radio de la gota interna, y lo comparamos con el coeficiente de difusión termal. Con esto calculamos una temperatura activa, obteniendo un valor de 2.7×10^4 K, dos órdenes de magnitud mayor que la temperatura ambiente, consistente con el experimento de gotas propulsadas por bacterias y trabajos previos. Estudiamos también el plano vertical, mostrando que el coeficiente de difusión en este plano es menor que en el horizontal, debido al atrapamiento geométrico.21150648https://hdl.handle.net/10533/246251instname: Conicytreponame: Repositorio Digital RI2.0info:eu-repo/grantAgreement//21150648info:eu-repo/semantics/dataset/hdl.handle.net/10533/93488http://repositorio.uchile.cl/handle/2250/174205info:eu-repo/semantics/openAccessAttribution-NonCommercial 3.0 Chilehttp://creativecommons.org/licenses/by-nc/3.0/cl/Ciencias NaturalesCiencias FísicasOtras Especialidades de la FísicaDynamics of confined microswimmers inside a droplet: From microactivity to macromovementDimámica de micronadadores confinados en una gota: Desde la microactividad al macromovmientoinfo:eu-repo/semantics/doctoralThesisinfo:eu-repo/semantics/publishedVersionTesisTesishttps://hdl.handle.net/10533/2462518ec95924-650a-4e02-8651-a5aba53e7a57virtual::56533-18ec95924-650a-4e02-8651-a5aba53e7a57virtual::56533-1CC-LICENSElicense_rdfapplication/octet-stream1379https://repositorio.anid.cl/bitstreams/241b5f8e-005c-4511-8a50-1d99254e9e4b/downloadf7a11d45fd81c28c2894e0236396e7f4MD51ORIGINALTesis_Doctorado_Gabriel_Ramos_Peroni_Final.pdfTesis para obtener el grado de Doctor en Ciencias mencion Fisica de la Universidad de Chileapplication/pdf36620098https://repositorio.anid.cl/bitstreams/75215581-1534-4b42-9841-df62a0948218/download1ddf1d310c5c7a49133f83f33bacd75dMD52LICENSElicense.txttext/plain1779https://repositorio.anid.cl/bitstreams/1c224aa3-755d-455b-bdae-917bb61fe8c3/download593a6e7305c66c56041a9f9e15a649c1MD53TEXTTesis_Doctorado_Gabriel_Ramos_Peroni_Final.pdf.txtExtracted texttext/plain146730https://repositorio.anid.cl/bitstreams/1f696080-42ac-4f5c-90f9-b874e3deb549/download1e32611cc89801e37da12f95df4ff817MD54THUMBNAILTesis_Doctorado_Gabriel_Ramos_Peroni_Final.pdf.jpgIM Thumbnailimage/jpeg4681https://repositorio.anid.cl/bitstreams/0a5f4f6d-b843-456c-b4d6-02e5a0d49c84/download7b4ab1cd4d73cf27f3881fb6407e7958MD5510533/246251oai:repositorio.anid.cl:10533/2462512023-07-24 18:21:45.45http://creativecommons.org/licenses/by-nc/3.0/cl/info:eu-repo/semantics/openAccesshttps://repositorio.anid.clRepositorio ANIDaletelier@anid.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