WO2008116950A1 - Method of generation of micrometric and submicrometric drops and bubbles by means of viscous coflows - Google Patents

Method of generation of micrometric and submicrometric drops and bubbles by means of viscous coflows Download PDF

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Publication number
WO2008116950A1
WO2008116950A1 PCT/ES2008/000159 ES2008000159W WO2008116950A1 WO 2008116950 A1 WO2008116950 A1 WO 2008116950A1 ES 2008000159 W ES2008000159 W ES 2008000159W WO 2008116950 A1 WO2008116950 A1 WO 2008116950A1
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Prior art keywords
drops
procedure
fluid
micrometric
bubbles
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PCT/ES2008/000159
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Spanish (es)
French (fr)
Inventor
Álvaro GÓMEZ MARÍN
Francisco DEL CAMPO CORTÉS
José Manuel GORDILLO ARIAS DE SAAVEDRA
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Universidad De Sevilla
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Publication of WO2008116950A1 publication Critical patent/WO2008116950A1/en

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
    • B01F23/00—Mixing according to the phases to be mixed, e.g. dispersing or emulsifying
    • B01F23/40—Mixing liquids with liquids; Emulsifying
    • B01F23/41—Emulsifying
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
    • B01F25/00—Flow mixers; Mixers for falling materials, e.g. solid particles
    • B01F25/30—Injector mixers
    • B01F25/31—Injector mixers in conduits or tubes through which the main component flows
    • B01F25/313—Injector mixers in conduits or tubes through which the main component flows wherein additional components are introduced in the centre of the conduit
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
    • B01F33/00—Other mixers; Mixing plants; Combinations of mixers
    • B01F33/30—Micromixers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
    • B01F2215/00—Auxiliary or complementary information in relation with mixing
    • B01F2215/04—Technical information in relation with mixing
    • B01F2215/0404—Technical information in relation with mixing theories or general explanations of phenomena associated with mixing or generalizations of a concept by comparison of equivalent methods

Definitions

  • the present invention describes a process for generating small drops or bubbles (dispersed phase) within a continuous phase, both of which are immiscible fluids.
  • the range of droplet sizes obtained by this procedure can range from one millimeter to smaller sizes of the bead (minimum droplet sizes of the order of 100 nanometers).
  • the size range of the bubbles obtained by this procedure is between the millimeter and the millimeter.
  • the diameter of the resulting jet decreases with respect to the injection size of the stream A.
  • the procedure object of the present invention is a simplification of previous procedures, and therefore an improvement, for the generation of emulsions composed of micrometric or nanometric drops, which are applicable to the Pharmaceutical Industry, the Food Industry, Medicine or Materials Science .
  • the same procedure can be used for the generation of monodisperse bubbles of micrometric size.
  • the monodispersed foam The result is of interest for Materials Science and for the Food Industry.
  • both methods firmly present an axial symmetry (axilsymmetric) in the zone of the nordase in which the jet is produced, although there are materializations of flor-focusing devices in practically two-dimensional geometries (Anna et al, Appl. Phys Lett, (2003), 82, 364-366, Gordillo et al., Phys. Fluids, (2004), 16, 2828-2834).
  • the capsules are generated by chemical processes of deposition of a substance on the surface of a drop of a compound or active ingredient.
  • the purpose of the outer cover which is usually elastic or rigid, is to protect the active principle that is inside.
  • the outer shell is made solid by some method (for example, by making the outer fluid a photopolymer that increases its viscosity or stiffens with ultraviolet light), solid capsules can be generated. Emulsions can be generated in these devices by simply injecting a liquid using any of the procedures outlined above in a bath of an immiscible liquid with the injected fluid.
  • the first procedure belongs to the family of devices known as flow focusing, and is protected by patents US 6174469, US 6187214 and US 6450189. In this case, as with the atomizers of the flow focusing type, the two concentric streams of fluid they are accelerated due to the favorable pressure gradient that exists between a pressurized chamber with gas and the outside.
  • the diameter of the inner and outer jets decreases and, finally, by a fundamentally capillary mechanism, the compound drops are generated. These compound drops can have diameters of the order of 100 microns.
  • the inner and outer concentric jets are accelerated using an electric field.
  • the capsules generated can have nanometric sizes (the capsules produced according to this procedure are the smallest ever generated), and are protected according to patents P200100231, PCT ES02 / 00047 and PCT US 02/02787.
  • This procedure has, however, the disadvantage compared to flow focusing devices that electric fields are necessary and that the Liquid flow rates are of the order of 1000 to 100 times lower than those that can be used in flow focusing technology.
  • Figure 1 Scheme of the geometric configuration of the device, which consists of a capillary tube, of internal diameter Di, which is housed inside another of a larger diameter, Do.
  • a flow rate Qi is injected through the inner tube, so that the output speed is substantially lower than that of the external current, Uo.
  • the internal current narrows and drops of sizes much smaller than Di.
  • FIG. 1 Materialization of the device in operation under arbitrary operating conditions.
  • Di 100 microns
  • Do 800 microns.
  • the inner and outer tubes are made of silica and glass respectively.
  • FIG. 3 Detail of the operation of the device as a device for producing micrometric drops.
  • the flow of the external liquid remains constant. It is observed that, when the internal flow decreases sufficiently (from c to a), the diameter of the drops obtained is even smaller than the spatial resolution of the image ( ⁇ 3 microns / pixel).
  • Drops of silicone oil in glycerin with sizes in the range of 1.2 to 1.8 microns, under arbitrary operating conditions.
  • the droplet size of the obtained microemulsions may be of the order of miera or less.
  • FIG. 1 Air bubbles of 20 microns in glycerin under arbitrary operating conditions. The operation of the device for the generation of microbubbles is shown. Description of the invention and example of materialization
  • the present invention aims at a new method for the controlled generation of drops (which could be composed) and bubbles within another fluid immiscible with the first, which has the following peculiarities:
  • the fluid domain in which the drops or bubbles are generated is delimited by the free space between two impervious tubes, one introduced inside the other (see Figure 1).
  • the centering thereof is not necessary since the same flow symmetry makes a natural centering (see example in figure 2).
  • a flow, appropriately regulated, of a liquid with a viscosity ⁇ 0 is injected through the tube of greater characteristic length.
  • a flow, appropriately regulated, Qi, of a fluid with viscosity ⁇ is injected through the inner tube.
  • the flow rate Qi is such that the output rate of the inner fluid is at least ten times lower than the speed of the outer stream, Uo.
  • the Reynolds number of the inner stream must be of unit or smaller order.
  • the external flow drags into the internal current, narrowing it, as shown in Figures 2 and 3.
  • the outer tube is cylindrical, with an inner diameter of 800 microns, while the inner tube is made of silica, also cylindrical and has an outer diameter of 150 microns and an inner one of 100 microns.
  • the length of the outer tube is 4 centimeters, while the part of the inner tube introduced outside, has a length of 1 centimeter.
  • the internal and external flow rates are introduced from pressurized tanks with compressed air, through tubes that narrow downstream to fit the dimensions of the outer tubes, Do (see Figure 1) and the inner tube, Di.

Abstract

The present invention describes a method for generating small drops or bubbles (disperse phase) within a continuous phase, wherein both fluids are inmiscible. The size range of the drops obtained by this method can range from one millimetre to sizes less than one micron (minimum sizes of drops of the order of 100 nanometres). In addition, the size range of bubbles obtained by this method is between one millimetre and one micron. The resulting monodisperse foam is useful for materials science and for the food industry.

Description

TÍTULO TITLE
Método de generación de gotas y burbujas micro y submicrométricas mediante cofluios viscososMethod of generating micro and submicron drops and bubbles using viscous cofluios
RESUMENSUMMARY
La presente invención describe un procedimiento para generar pequeñas gotas o burbujas (fase dispersa) en el seno de una fase continua, siendo ambos fluidos inmiscibles. El rango de tamaños de las gotas obtenidas mediante este procedimiento puede ir desde el milímetro a tamaños inferiores de Ia miera (tamaños mínimos de gotas del orden de los 100 nanómetros). Por otra parte, el rango de tamaños de las burbujas obtenidas por este procedimiento está comprendido entre el milímetro y Ia miera. Cuando una corriente de un fluido A descarga de manera paralela en el seno de otro fluido B que se mueve a una velocidad superior, siendo A y B inmiscibles, y los números de Reynolds característicos de ambas corrientes son ambos inferiores a Ia unidad, siendo el número capilar de orden unidad o mayor, se desarrolla un chorro de A en B, que posteriormente rompe en gotas. Cuando el cociente entre Ia velocidad de inyección de Ia corriente de fluido A y Ia de B decrece, el diámetro del chorro resultante decrece con respecto al tamaño de inyección de Ia corriente A. Controlando simplemente Ia relación de velocidades, podemos controlar el tamaño de los chorros resultantes, que pueden tener dimensiones inferiores a Ia miera. La rotura capilar de estos chorros produce gotas o burbujas de tamaños característicos del orden del chorro.The present invention describes a process for generating small drops or bubbles (dispersed phase) within a continuous phase, both of which are immiscible fluids. The range of droplet sizes obtained by this procedure can range from one millimeter to smaller sizes of the bead (minimum droplet sizes of the order of 100 nanometers). On the other hand, the size range of the bubbles obtained by this procedure is between the millimeter and the millimeter. When a current of a fluid A discharges in parallel within another fluid B that moves at a higher speed, being A and B immiscible, and the Reynolds numbers characteristic of both currents are both lower than the unit, being the capillary number of unit or greater order, a jet of A in B develops, which subsequently breaks into drops. When the ratio between the injection speed of the fluid stream A and that of B decreases, the diameter of the resulting jet decreases with respect to the injection size of the stream A. By simply controlling the speed ratio, we can control the size of the resulting jets, which may have dimensions smaller than the mine. The capillary rupture of these jets produces drops or bubbles of characteristic sizes of the order of the jet.
Mediante este procedimiento se consiguen unas gotas extremadamente pequeñas, utilizando únicamente los esfuerzos viscosos que se generan de manera natural cuando dos corrientes viscosas fluyen paralelamente y los números de Reynolds característicos de ambas corrientes son inferiores a Ia unidad y el número capilar es superior a una cantidad de orden unidad.Through this procedure, extremely small drops are achieved, using only the viscous stresses that are generated naturally when two viscous currents flow in parallel and the characteristic Reynolds numbers of both currents are less than the unit and the capillary number is greater than an amount of unit order.
El procedimiento objeto de Ia presente invención supone una simplificación de procedimientos previos, y por tanto una mejora, para Ia generación de emulsiones compuestas por gotas micrométricas o nanométricas, que son aplicables a Ia Industria Farmacéutica, Ia Industria Alimenticia, Medicina o Ciencia de los Materiales. El mismo procedimiento puede ser utilizado para Ia generación de burbujas monodispersas de tamaño micrométrico. La espuma monodispersa resultante es de interés para Ia Ciencia de los Materiales y para Ia Industria Alimenticia.The procedure object of the present invention is a simplification of previous procedures, and therefore an improvement, for the generation of emulsions composed of micrometric or nanometric drops, which are applicable to the Pharmaceutical Industry, the Food Industry, Medicine or Materials Science . The same procedure can be used for the generation of monodisperse bubbles of micrometric size. The monodispersed foam The result is of interest for Materials Science and for the Food Industry.
ESTADO DE LA TÉCNICASTATE OF THE TECHNIQUE
En los últimos años se han multiplicado los estudios, invenciones y aplicaciones relacionadas con el control microscópico de las corrientes fluidas, y entre estos estudios e invenciones destacan los que involucran superficies libres o interfases entre dos fluidos inmiscibles para poder conseguir estructuras microscópicas (micro-gotas, micro-burbujas, micro-cápsulas, etc.) de forma reproducible y robusta. Conviene destacar aquí dos fenómenos/inventos peculiares representativos de Ia generación de micro-chorros: (i) el electrospray o producción de micro-chorros de líquido mediante fuerzas electrostáticas, conocido desde hace siglos, y (i¡) el "flow focusing" capilar, que emplea fuerzas de presión (puramente mecánicas) y un orificio de "enfocamiento" para generar el chorro. Respondiendo a su geometría, ambos métodos presentan genuinamente una simetría axial (axilsimétricos) en Ia zona de Ia ¡nterfase en Ia que se produce el chorro, aunque existen materializaciones de dispositivos flor-focusing en geometrías prácticamente bidimensionales (Anna et al, Appl. Phys. Lett, (2003), 82, 364-366, Gordillo et al, Phys. Fluids, (2004), 16, 2828-2834).In recent years, studies, inventions and applications related to the microscopic control of fluid currents have multiplied, and among these studies and inventions are those that involve free surfaces or interfaces between two immiscible fluids in order to achieve microscopic structures (micro-drops , micro-bubbles, micro-capsules, etc.) in a reproducible and robust way. It is worth highlighting here two peculiar phenomena / inventions representative of the generation of micro-jets: (i) the electrospray or production of micro-jets of liquid by electrostatic forces, known for centuries, and (i¡) the capillary "flow focusing" , which uses pressure forces (purely mechanical) and a "focusing" hole to generate the jet. Responding to their geometry, both methods genuinely present an axial symmetry (axilsymmetric) in the zone of the nordase in which the jet is produced, although there are materializations of flor-focusing devices in practically two-dimensional geometries (Anna et al, Appl. Phys Lett, (2003), 82, 364-366, Gordillo et al., Phys. Fluids, (2004), 16, 2828-2834).
En el caso del electrospray, los principales inconvenientes provienen de:In the case of electrospray, the main drawbacks come from:
(i) Ia inherente e inevitable dependencia del fenómeno respecto a las propiedades eléctricas del líquido, Io cual limita enormemente Ia libertad paramétrica fisicoquímica del método (aunque hayan surgido aplicaciones de enorme relevancia en bioquímica -espectrometría de masas de moléculas biológicas),(i) the inherent and inevitable dependence of the phenomenon on the electrical properties of the liquid, which greatly limits the physicochemical parametric freedom of the method (although applications of enormous relevance in biochemistry - mass spectrometry of biological molecules) have arisen,
(ii) Ia pequeña productividad de método (caudal másico muy pequeño) y Ia dificultad para "escalarlo" o "multiplicarlo" (multiplexing) (iii) Ia mediocre robustez del método por su gran dependencia de las condiciones superficiales y tamaños de los tubos de alimentación de los líquidos.(ii) the small productivity of the method (very small mass flow) and the difficulty in "scaling" or "multiplying" (multiplexing) (iii) the mediocre robustness of the method due to its great dependence on surface conditions and tube sizes. liquid feeding.
En "flow focusing" axilsimétrico, aunque se eliminan los inconvenientes de Ia dependencia respecto a las propiedades del fluido, aún se tienen problemas respecto al alineamiento de los tubos de alimentación respecto a los orificios de enfocamiento. En las implementaciones de tipo flow-focusing 2D, el problema principal proviene del mojado con las superficies que confinan al fluido a dispersar. La razón por Ia que Ia producción controlada de partículas micro y submicrométricas supone una de las líneas de investigación más activas dentro de! campo de Ia Mecánica de Fluidos, es por el gran número de aplicaciones tanto científicas como tecnológicas que tiene. Por ejemplo, como se señala en el reciente artículo "Micro- and nanoparticles vía capillary flows", Barrero y Loscertales, Annual Review of Fluid Mechanics, (2007), 39, 89-106, Ia absorción eficiente de nuevos fármacos por los tejidos y órganos requiere que el producto activo se encuentre confinado en gotas de tamaños sustancialmente menores que 10 mieras. Las emulsiones formadas por gotas de tamaño micrométrico también tienen aplicación en muchos otros campos, como Ia industria alimenticia, o Ia ciencia de los materiales (fabricación de dispositivos ópticos mediante cristales líquidos), entre otros. En Ia actualidad existen un número considerable de procedimientos que permiten conseguir este tipo de microemulsiones, con tamaños característicos de gotas en el entorno de las diez mieras. Sin embargo, sólo existe una técnica que consiga bajar el tamaño por debajo de esta cota de manera eficiente: Ia de los electrosprays simples y compuestos (Loscertales, Barrero y otros, Science, (2002), 295, 5560). Aquí presentamos una técnica que prescinde del uso de campos eléctricos o de surfactantes y que posee una geometría tan sencilla, que carece de los problemas de centrado de los dispositivos tipo flow focusing tridimensional, Gañán-Calvo y Gordillo, Phys. Rev. Lett. (2001), 87, 274501 , o de mojado con las superficies adyacentes como las técnicas que hacen uso de dispositivos tipo flow-focusing creados con los métodos de soft-lithography (Anna et al, Appl. Phys. Lett, (2003), 82, 364-366). Estos métodos, además de ser más complejos en cuanto a su geometría puesto que Ia corriente a dispersar ha de ser enfocada a través de un orificio o canal de dimensión menor que Ia aguja inyectora, son incapaces de conseguir tamaños de gotas por debajo de las 5 mieras de manera sistemática.In axilsimetric "flow focusing", although the inconveniences of dependence with respect to the properties of the fluid are eliminated, there are still problems regarding the alignment of the feeding tubes with respect to the holes of focus. In 2D flow-focusing implementations, the main problem comes from wetting with the surfaces that confine the fluid to be dispersed. The reason why the controlled production of micro and submicron particles is one of the most active research lines within! Fluid Mechanics field, it is because of the large number of scientific and technological applications that it has. For example, as indicated in the recent article "Micro- and nanoparticles via capillary flows", Barrero and Loscertales, Annual Review of Fluid Mechanics, (2007), 39, 89-106, the efficient absorption of new drugs by tissues and organs require that the active product be confined in drops of sizes substantially smaller than 10 microns. Emulsions formed by micrometer-sized drops also have application in many other fields, such as the food industry, or the science of materials (manufacture of optical devices using liquid crystals), among others. At present there are a considerable number of procedures that allow this type of microemulsions to be achieved, with characteristic droplet sizes in the environment of the ten microns. However, there is only one technique that can reduce the size below this level efficiently: that of simple and compound electrosprays (Loscertales, Barrero and others, Science, (2002), 295, 5560). Here we present a technique that dispenses with the use of electric fields or surfactants and has such a simple geometry that it lacks the problems of centering the three-dimensional flow focusing devices, Gañán-Calvo and Gordillo, Phys. Rev. Lett. (2001), 87, 274501, or wetting with adjacent surfaces such as techniques that make use of flow-focusing devices created with soft-lithography methods (Anna et al, Appl. Phys. Lett, (2003), 82, 364-366). These methods, in addition to being more complex in terms of their geometry since the current to be dispersed has to be focused through an orifice or channel of smaller dimension than the injector needle, are unable to achieve droplet sizes below 5 you systematically
En los últimos tiempos, existe un interés creciente por parte de Ia industria alimenticia, farmacéutica o química de generar cápsulas que contengan en su interior un principio activo y que exteriormente están recubiertas de una coraza flexible o rígida. Son innumerables las patentes que registran un procedimiento para Ia producción de cápsulas o de emulsiones. En el caso de cápsulas para aplicación alimenticia se encuentran los ejemplos de las patentes AU754712 y EP1263451. En aplicaciones a Ia industria química (principalmente empresas dedicadas a Ia fabricación de detergentes), EP1288287 y WO03002160. Las aplicaciones a Ia industria farmacéutica son las más comunes y cuentan con innumerables registros, entre los que cabe citar WO03004003, WO0041740, US6514526, EP1151746. En Ia mayor parte de estos ejemplos, las cápsulas son generadas mediante procesos químicos de deposición de una sustancia sobre Ia superficie de una gota de un compuesto o principio activo. El fin de Ia cubierta externa, que suele ser elástica o rígida, es Ia de proteger el principio activo que se encuentra en su interior. Existen procedimientos, patentados inicialmente en Ia Universidad de Sevilla, que siguen un procedimiento diferente para encapsular líquidos o generar emulsiones. Ambos se basan en hacer fluir de manera coaxial dos corrientes fluidas inmiscibles. Es bien sabido que los chorros cilindricos se rompen en gotas debido al crecimiento de una inestabilidad capilar, también conocida como inestabilidad de Rayleigh. Cuando esta rotura se produce de manera simultánea en los chorros interior y exterior, se generan gotas que en su interior poseen otras gotas de menor tamaño. Si Ia cubierta externa se hace sólida mediante algún procedimiento (por ejemplo, haciendo que el fluido exterior sea un fotopolímero que aumente su viscosidad o que se rigidice con, luz ultravioleta), pueden generarse cápsulas sólidas. Las emulsiones pueden generarse en estos dispositivos sin más que inyectar un líquido utilizando cualquiera de los procedimientos antes señalados en un baño de un líquido inmiscible con el fluido inyectado. El primer procedimiento pertenece a Ia familia de dispositivos conocidos como flow focusing, y está protegido por las patentes US 6174469, US 6187214 y US 6450189. En este caso, al igual que ocurre con los atomizadores del tipo flow focusing las dos corrientes concéntricas de fluido son aceleradas debido al gradiente favorable de presión que existe entre una cámara presurizada con gas y el exterior. El diámetro de los chorros interior y exterior decrece y, finalmente, por un mecanismo fundamentalmente capilar, se generan las gotas compuestas. Estas gotas compuestas pueden llegar a tener diámetros del orden de las 100 mieras. Por otra parte, con Ia tecnología conocida como Y-Flow, los chorros concéntricos interior y exterior son acelerados haciendo uso de un campo eléctrico. Las cápsulas generadas pueden llegar a tener tamaños nanométricos (las cápsulas producidas según este procedimiento son las más pequeñas jamás generadas), y está protegido según las patentes P200100231 , PCT ES02/00047 y PCT US 02/02787. Este procedimiento tiene, sin embargo, Ia desventaja frente a los dispositivos flow focusing de que son necesarios campos eléctricos y que los caudales de líquido son del orden de 1000 a 100 veces menores que los que se pueden utilizar en Ia tecnología flow focusing.In recent times, there is a growing interest on the part of the food, pharmaceutical or chemical industry to generate capsules that contain an active ingredient inside and that are externally coated with a flexible or rigid shell. There are innumerable patents that register a procedure for the production of capsules or emulsions. In the case of capsules for food application are the examples of patents AU754712 and EP1263451. In applications to the chemical industry (mainly companies dedicated to the manufacture of detergents), EP1288287 and WO03002160. Applications to the pharmaceutical industry are the most common and have innumerable records, among which WO03004003, WO0041740, US6514526, EP1151746. In most of these examples, the capsules are generated by chemical processes of deposition of a substance on the surface of a drop of a compound or active ingredient. The purpose of the outer cover, which is usually elastic or rigid, is to protect the active principle that is inside. There are procedures, initially patented at the University of Seville, which follow a different procedure to encapsulate liquids or generate emulsions. Both are based on coaxially flowing two immiscible fluid currents. It is well known that cylindrical jets break into droplets due to the growth of capillary instability, also known as Rayleigh instability. When this break occurs simultaneously in the inner and outer jets, drops are generated that have smaller droplets inside. If the outer shell is made solid by some method (for example, by making the outer fluid a photopolymer that increases its viscosity or stiffens with ultraviolet light), solid capsules can be generated. Emulsions can be generated in these devices by simply injecting a liquid using any of the procedures outlined above in a bath of an immiscible liquid with the injected fluid. The first procedure belongs to the family of devices known as flow focusing, and is protected by patents US 6174469, US 6187214 and US 6450189. In this case, as with the atomizers of the flow focusing type, the two concentric streams of fluid they are accelerated due to the favorable pressure gradient that exists between a pressurized chamber with gas and the outside. The diameter of the inner and outer jets decreases and, finally, by a fundamentally capillary mechanism, the compound drops are generated. These compound drops can have diameters of the order of 100 microns. On the other hand, with the technology known as Y-Flow, the inner and outer concentric jets are accelerated using an electric field. The capsules generated can have nanometric sizes (the capsules produced according to this procedure are the smallest ever generated), and are protected according to patents P200100231, PCT ES02 / 00047 and PCT US 02/02787. This procedure has, however, the disadvantage compared to flow focusing devices that electric fields are necessary and that the Liquid flow rates are of the order of 1000 to 100 times lower than those that can be used in flow focusing technology.
Descripción de las figurasDescription of the figures
Figura 1. Esquema de Ia configuración geométrica del dispositivo, que consta de un tubo capilar, de diámetro interior Di, que se encuentra alojado en el interior de otro de mayor diámetro, Do. Por el tubo interior se inyecta un caudal Qi, de manera que Ia velocidad de salida sea sustancialmente menor que Ia de Ia corriente exterior, Uo. En el rango paramétrico adecuado, Ia corriente interior se estrecha y se generan gotas de tamaños muy inferiores a Di.Figure 1. Scheme of the geometric configuration of the device, which consists of a capillary tube, of internal diameter Di, which is housed inside another of a larger diameter, Do. A flow rate Qi is injected through the inner tube, so that the output speed is substantially lower than that of the external current, Uo. In the appropriate parametric range, the internal current narrows and drops of sizes much smaller than Di.
Figura 2. Materialización del dispositivo en funcionamiento bajo condiciones de operación arbitrarias. En este caso, Di=100 mieras, Do=800 mieras. Los tubos interior y exterior son de sílica y de cristal respectivamente.Figure 2. Materialization of the device in operation under arbitrary operating conditions. In this case, Di = 100 microns, Do = 800 microns. The inner and outer tubes are made of silica and glass respectively.
Figura 3. Detalle del funcionamiento del dispositivo como aparato de producción de gotas micrométricas. En las tres imágenes, el caudal del líquido exterior se mantiene constante. Se observa que, cuando el caudal interior disminuye Io suficiente (de c hacia a), el diámetro de las gotas obtenidas es incluso menor que Ia resolución espacial de Ia imagen (~ 3 micras/píxel).Figure 3. Detail of the operation of the device as a device for producing micrometric drops. In all three images, the flow of the external liquid remains constant. It is observed that, when the internal flow decreases sufficiently (from c to a), the diameter of the drops obtained is even smaller than the spatial resolution of the image (~ 3 microns / pixel).
Figura 4. Gotas de aceite de silicona en glicerina, con tamaños en el rango de las 1.2 a las 1.8 mieras, en condiciones de operación arbitrarias. Como puede observarse, el tamaño de las gotas de las microemulsiones obtenidas, puede ser del orden de Ia miera o inferior.Figure 4. Drops of silicone oil in glycerin, with sizes in the range of 1.2 to 1.8 microns, under arbitrary operating conditions. As can be seen, the droplet size of the obtained microemulsions may be of the order of miera or less.
Figura 5. Burbujas de aire de 20 mieras en glicerina en condiciones de operación arbitrarias. Se muestra el funcionamiento de dispositivo para Ia generación de microburbujas. Descripción de Ia invención y ejemplo de materializaciónFigure 5. Air bubbles of 20 microns in glycerin under arbitrary operating conditions. The operation of the device for the generation of microbubbles is shown. Description of the invention and example of materialization
La presente invención tiene por objeto un nuevo método para Ia generación controlada de gotas (que podrían ser compuestas) y burbujas en el seno de otro fluido inmiscible con el primero, que presenta las siguientes peculiaridades:The present invention aims at a new method for the controlled generation of drops (which could be composed) and bubbles within another fluid immiscible with the first, which has the following peculiarities:
El dominio fluido en el que se generan las gotas o burbujas está delimitado por el espacio libre entre dos tubos impermeables, uno introducido en el interior del otro (véase Ia figura 1). El centrado de los mismos no es necesario dado que Ia misma simetría del flujo hace un centrado natural (véase ejemplo en figura 2). Por el tubo de mayor longitud característica se inyecta un caudal, regulado de manera apropiada, de un líquido con una viscosidad μ0. Por el tubo interior se inyecta un caudal, regulado de manera apropiada, Qi, de un fluido con viscosidad μ¡. El caudal Qi es tal que Ia velocidad de salida del fluido interior sea, al menos, diez veces inferior Ia velocidad de Ia corriente exterior, Uo.The fluid domain in which the drops or bubbles are generated is delimited by the free space between two impervious tubes, one introduced inside the other (see Figure 1). The centering thereof is not necessary since the same flow symmetry makes a natural centering (see example in figure 2). A flow, appropriately regulated, of a liquid with a viscosity μ 0 is injected through the tube of greater characteristic length. A flow, appropriately regulated, Qi, of a fluid with viscosity μ¡ is injected through the inner tube. The flow rate Qi is such that the output rate of the inner fluid is at least ten times lower than the speed of the outer stream, Uo.
Debe ocurrir que los esfuerzos de Ia corriente exterior, sean mayores que los de confinamiento por tensión superficial (número capilar de orden unidad o mayor) y que el número de Reynolds de Ia corriente exterior sea mucho menor que Ia unidad. El número de Reynolds de Ia corriente interior debe ser de orden unidad o menor.It must happen that the efforts of the external current are greater than those of confinement by surface tension (capillary number of unit or greater order) and that the Reynolds number of the external current is much smaller than the unit. The Reynolds number of the inner stream must be of unit or smaller order.
En el rango de parámetros apropiado, el flujo exterior arrastra a Ia corriente interior, estrechándola, tal y como se muestra en las figuras 2 y 3. Por ejemplo, en Ia figura 3, el fluido exterior es glicerina μo=95O centipoises, Ia velocidad Uo=O.1 m/s. El fluido interior es aceite de silicona, de viscosidad μ¡=19.36 centipoises. En esta materialización, el tubo exterior es cilindrico, de diámetro interior 800 mieras, mientras que el tubo interior es de sílica, también cilindrico y tiene un diámetro exterior de 150 mieras y uno interior de 100 mieras. El caudal interior, Qi es, en Ia primera fotografía (a) Qi=3.4 nanolitros/s, (b) 9.12 nanolitros/s y (c) 26.2 nanolitros/s. La longitud del tubo exterior es de 4 centímetros, mientras que Ia parte del tubo interior introducida en el exterior, tiene una longitud de 1 centímetro. Los caudales interior y exterior son introducidos desde depósitos presurizados con aire comprimido, a través de tubos que se estrechan aguas abajo hasta encajar con las dimensiones de los tubos exterior, Do (véase Ia figura 1 ) y Ia del tubo interior, Di. In the appropriate range of parameters, the external flow drags into the internal current, narrowing it, as shown in Figures 2 and 3. For example, in Figure 3, the external fluid is glycerin μ o = 95O centipoise, Ia speed Uo = O.1 m / s. The inner fluid is silicone oil, of viscosity μ¡ = 19.36 centipoise. In this materialization, the outer tube is cylindrical, with an inner diameter of 800 microns, while the inner tube is made of silica, also cylindrical and has an outer diameter of 150 microns and an inner one of 100 microns. The internal flow, Qi is, in the first photograph (a) Qi = 3.4 nanoliters / s, (b) 9.12 nanoliters / s (c) 26.2 nanoliters / s. The length of the outer tube is 4 centimeters, while the part of the inner tube introduced outside, has a length of 1 centimeter. The internal and external flow rates are introduced from pressurized tanks with compressed air, through tubes that narrow downstream to fit the dimensions of the outer tubes, Do (see Figure 1) and the inner tube, Di.

Claims

REIVINDICACIONES
1.- Procedimiento para generar chorros de tamaño micrométrico y nanométrico caracterizado porque un caudal Q¡ de un fluido A, de viscosidad μ¡ y densidad ρ¡ inyectado desde un tubo de diámetro D y de manera paralela a otro flujo fluido B de viscosidad μ0, densidad p0 y de velocidad característica U0 con A y B inmiscibles entre sí, siendo los números de Reynolds característicos de ambas corrientes tales que p0u0D/μ0<i y PÍQÍ/ (Dμo) <io y siendo el número capilar μouo/σ>0.75, con σ Ia tensión superficial entre los dos fluidos, genera un chorro de líquido A en el seno de B de diámetro d=[4Q¡/(π Uo)]1/2 1.- Procedure for generating micrometric and nanometric sized jets characterized in that a flow rate Q¡ of a fluid A, of viscosity μ¡ and density ρ¡ injected from a tube of diameter D and parallel to another fluid flow B of viscosity μ 0 , density p 0 and characteristic velocity U 0 with A and B immiscible with each other, the Reynolds numbers being characteristic of both currents such that p 0 or 0 D / μ 0 <i and P Í Q Í / (Dμ o ) < io and being the capillary number μ o u or /σ>0.75, with σ the surface tension between the two fluids, generates a jet of liquid A within B of diameter d = [4Q¡ / (π U o )] 1/2
2.- Procedimiento de generación de chorros de tamaño micrométrico y nanométrico siguiendo el procedimiento de generación de chorros de Ia reivindicación 1 , caracterizado porque el caudal Q¡ y Ia velocidad U0 son tales que [4Q¡/(π Uo)]1/2<1 mm.2. Procedure for generating micrometric and nanometric sized jets following the method of generating jets of claim 1, characterized in that the flow rate Q¡ and the speed U 0 are such that [4Q¡ / (π U o )] 1 / 2 <1 mm.
3.- Procedimiento de generación de gotas de tamaño micrométrico y nanométrico siguiendo el procedimiento de generación de chorros de las reivindicaciones 1 y 2, caracterizado porque Ia rotura capilar del chorro genera gotas de diámetros de 1 a 20 veces el diámetro del chorro.3. Procedure for generating micrometric and nanometric size drops following the jet generation procedure of claims 1 and 2, characterized in that the capillary rupture of the jet generates drops of diameters from 1 to 20 times the diameter of the jet.
4.- Procedimiento de generación de emulsiones según el procedimiento descrito en las reivindicaciones 1 y 24. Emulsion generation process according to the procedure described in claims 1 and 2
5.- Procedimiento de generación de burbujas según el procedimiento descrito en las reivindicaciones 1 y 2, caracterizado porque el fluido interior B es un gas.5. Bubble generation process according to the method described in claims 1 and 2, characterized in that the internal fluid B is a gas.
6.- Procedimiento de generación de espumas según el procedimiento descrito en las reivindicaciones 1 y 2 donde el fluido interior B es un gas. 6. Foam generation method according to the method described in claims 1 and 2 wherein the inner fluid B is a gas.
PCT/ES2008/000159 2007-03-27 2008-03-24 Method of generation of micrometric and submicrometric drops and bubbles by means of viscous coflows WO2008116950A1 (en)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CH563807A5 (en) * 1973-02-14 1975-07-15 Battelle Memorial Institute Fine granules and microcapsules mfrd. from liquid droplets - partic. of high viscosity requiring forced sepn. of droplets
WO1999030832A1 (en) * 1997-12-17 1999-06-24 Universidad De Sevilla Stabilized capillary microjet and devices and methods for producing same
ES2140998A1 (en) * 1996-05-13 2000-03-01 Univ Sevilla Liquid atomization process
ES2180405A1 (en) * 2001-01-31 2003-02-01 Univ Sevilla Device and method for producing stationary multi-component liquid capillary streams and micrometric and nanometric sized capsules

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CH563807A5 (en) * 1973-02-14 1975-07-15 Battelle Memorial Institute Fine granules and microcapsules mfrd. from liquid droplets - partic. of high viscosity requiring forced sepn. of droplets
ES2140998A1 (en) * 1996-05-13 2000-03-01 Univ Sevilla Liquid atomization process
WO1999030832A1 (en) * 1997-12-17 1999-06-24 Universidad De Sevilla Stabilized capillary microjet and devices and methods for producing same
ES2180405A1 (en) * 2001-01-31 2003-02-01 Univ Sevilla Device and method for producing stationary multi-component liquid capillary streams and micrometric and nanometric sized capsules

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