DE102012104867A1 - Micro-fluidic system for supplying nozzle set with fluids, has integrated inflow of focusing fluid going to reservoir of focusing fluid, where pairs of feed channels lead in accordance with multiple nozzles - Google Patents

Abstract

The micro-fluidic system has an integrated inflow (105) of a focusing fluid going to a reservoir (103) of the focusing fluid. Pairs of feed channels (106) are provided to lead in accordance with multiple nozzles and take the focusing fluid to the reservoir of the focusing fluid. The hydraulic resistance of each of the feed channels of the focusing fluid is greater than the hydraulic resistance of the reservoir of the focusing fluid, preferably 50 times greater, and particularly 10000 times greater. The system is manufactured from polycarbonate, polyethylene or polypropylene.

Description

The present invention relates to a microfluidic system for supplying fluid to a nozzle set comprising an integral inflow of the focussing fluid going to a reservoir of focussing fluid, and n ≥ 1 pairs of focussing fluid inflow channels beginning at the focussing fluid reservoir take and lead to n nozzles accordingly.

The present invention also discloses a method for evenly distributing the fluids within a microfluidic system consisting of at least two sets of channels that are planar analogs of axisymmetric nozzles. The invention also includes a microfluidic system utilizing the above method of distributing the fluids.

The atomization of a fluid consists in converting some of the energy that supplies a process into the surface energy. As a rule, only a small part of the energy that supplies an atomization process is converted into surface energy. This dependence is quantitatively described by a parameter that is the quotient of the surface energy and the energy supplying the atomization process. The energy that supplies the process can come from different sources, most of it is mechanical, electromechanical or purely electrostatic energy.

The operating principle of pneumatic atomizers is that they divide the liquid jet by a gas flow. For most atomizers known in the art, the desensitization process proceeds with very little yield due to significant mechanical energy dissipation. To date, dozens of nozzle types have been developed with significantly different sputtering yields and are also known in the art. The optimization of a nozzle of a pneumatic atomizer is to use as correctly as possible the energy that supplies the process. In choosing the most accurate atomizer geometry, the following factors are considered in practice: maximizing surface energy, minimizing the amount of gas (gas pressure), and, not less important, ensuring minimal coalescence of the droplets generated in the nozzle. As a general principle, it could be assumed that the more complicated and expensive the device, the more efficient the atomization taking place therein.

Depending on the application, whether in use in industrial wetting on a huge scale (in kg or tonnes of liquid to be atomized), or in biotechnology and cell cultivation in polymer microcapsules, various requirements for monodispersity of the droplet distribution of the liquid to be atomized. And so, in some applications, high monodispersity is crucial, and less important in others. As a general principle, atomizers with lower productivity, expressed in kilograms of the liquid to be atomized per unit of time, should offer better monodispersibility. A peculiar solution would therefore be one that would simultaneously ensure a high sputtering yield and, in parallel, high productivity, which is of crucial importance in industrial applications.

In particular, in the prior art, a method for hydrodynamic focusing comes - "flow-focusing" ( AM Gañán-Calvo, Phys. Rev, Lett. 80, 285, (1998) ) for use. The construction of the nozzle, according to the above method, consists in exact adaptation of two thin-walled tubes (capillaries), so that the appropriate - coaxial - symmetry is ensured. Through the inner capillary, the fluid to be atomized in the nozzle, and the atomizing (focussing) fluid is supplied through the outer capillary. An additional, very important design element of the hydrodynamic focusing nozzle is a plate having an opening (or alternately a ring having a circular cross-section) set perpendicular to the nozzle axis so that the opening is exactly in the lumen of the nozzle orifice. The diameter of the inner capillary and the diameter of the opening must meet one condition: the dimension of the opening in the plate must be several times smaller than the diameter of the inner capillary. Again, the distance between the mouth of the coaxial capillaries and the plate need not be greater than the multiple diameter of the inner capillary. The above solution offers a very high monodispersibility of the size distribution of the drops to be produced. For example, for a capillary having a cross section of 100 to 300 microns, positioned at a distance of 1 mm from the plate having a diameter of 100 microns, an aerosol having a droplet diameter of about 10 microns to about 30 microns can be produced. The half-width (dispersion) of the droplet size distribution for the above example is not larger than 10%. However, in view of a specific mechanism of fragmentation of the liquid jet, hydrodynamic focusing does not allow to achieve high productivity from a single nozzle (in kilograms of the liquid to be atomized per unit time). Another limitation of this method is the requirement to process and adapt very precisely the details of which the nozzle elements are made. In practice, the necessary manufacturing accuracy of the axisymmetric Nozzle elements achieved through the use of high grade steels. Not without importance here is the proliferation and greater availability of devices for the precise machining of steel details, or metal details in general. The assembly of a nozzle from the components is carried out by hand, because the required degree of adaptation of the details using commercially available on the market devices is not achievable.

The use of polymeric materials for precise nozzle fabrication is limited because of a lower accuracy in the fabrication of the plastic details. High productivity of most processes based on polymer materials, especially recognizable in injection technology, does not guarantee the desired dimensional tolerance. Plastic nozzles made by the methods known in the art produce aerosols having a broad size distribution. A barrier to industrial applications also represented the difficulties in finishing the plastic details.

Another barrier to the development of techniques for producing monodisperse aerosols is a limited ability to integrate nozzles. High productivity is at the expense of a wide range of droplet sizes. One example of such a solution is the modification of the hydrodynamic focusing method - the Flow -Blurring technique used by A. Gañán-Calvo ( AM Gañán-Calvo, Appl. Phys. Lett. 86, 214101 (2005) . WO / 1999 / 030832A1 ) was proposed. Similar to the classic solution of hydrodynamic focusing, the nozzle consists of two coaxial capillaries. Through the inner capillary, a fluid to be atomized in the nozzle, and a focusing fluid is supplied through the outer capillary, perpendicular to the nozzle axis, a plate is mounted with an opening, wherein the opening is located exactly in the lumen of the nozzle orifice. The modification of the method is that the conditions imposed on mutual distances and diameters of the nozzle elements are changed: the dimensions of the diameter of the inner capillary and the diameter of the opening in the plate must be comparable, and the distance between the mouth of the coaxial capillaries and the plate must correspond to a 1/4 diameter of the inner capillary. The above solution allows the productivity of a single nozzle to increase even by an order of magnitude. The dispersion of the size distribution of the droplets produced in the modified nozzle, on the other hand, is significantly worsened (increased), ie multiply.

There is currently no technology that can produce a high quality aerosol on the industrial multi-kilogram scale. In hydrodynamic focusing technology, increasing productivity is only possible by assembling the nozzles in multi-nozzle sets. To reproducibly generate an aerosol, equal conditions must be ensured for each individual nozzle in a nozzle set. In particular, it is necessary to provide both individually controlled, separate liquid feeds to each nozzle in the nozzle set, as well as, more complicatedly, to ensure the same gas pressure for each inflow of the focussing gas. In practice, this solution is very complicated and expensive, and thus extremely unfavorable in industrial applications.

The object of the present invention is to propose an efficient and economical device for generating aerosols. In the solution according to the invention, a process for the production of a microfluidic system and for the formation of aerosols with a well-defined droplet size distribution by passing the fluids through a suitable microfluidic system and the above-mentioned microfluidic system has been presented. The invention is based on such organization of the flow in a microfluidic system that the fluids flow first into a large reservoir, and out of the reservoir through resistance channels to two or more sets of channels, the equivalents of the centrosymmetric axial jets. The resistance channels are characterized by the same hydraulic resistance, and the hydraulic resistance is significantly greater than the hydraulic resistance of the reservoir and hydraulic resistance of the nozzle orifice.

According to the invention, a microfluidic system for supplying fluid to a nozzle set, comprising an integral inflow of the focussing fluid going to a reservoir of focussing fluid, and n ≥ 1 pairs of focussing fluid inflow channels beginning at the focussing fluid reservoir and leading to n nozzles is characterized in that the hydraulic resistance R of each of the inflow channels of the focussing fluid is significantly greater than the hydraulic resistance r of the reservoir of focussing fluid, preferably 50 times greater, more preferably 100 times greater, and am most preferably 10,000 times larger.

Preferably, the cross-sectional area a of each of the inflow channels of the focusing fluid is significantly smaller than the cross-sectional area A of the reservoir of the focussing fluid, more preferably 50 times smaller, even more preferably 100 times smaller, and most preferably 10000 times smaller.

Preferably, the longest cross-sectional dimension d of each of the inflow channels of the focussing fluid is significantly smaller than the longest cross-sectional dimension D of the focussing fluid reservoir, more preferably 50 times smaller, even more preferably 100 times smaller, and most preferably 10000 times smaller.

In a preferred embodiment, the system according to the invention is made of polycarbonate, polyethylene, polypropylene or another mechanically or thermally deformable polymer.

Preferably, n = 1, 2, 6, 10, 25 or 100.

Detailed description of the invention

The preferred embodiments are explained in more detail below with reference to figures of the accompanying drawings. Hereby show:

1 Schematic representation of an exemplary microfluidic system according to the invention - in the projection from above (left) and in cross section (right);

2 Recording of an exemplary, manufactured according to the invention microfluidic system, which is explained in more detail in the embodiment 1;

3 Recording of an exemplary, manufactured according to the invention microfluidic system, which is explained in more detail in Example 2;

4 Recording of an exemplary, manufactured according to the invention microfluidic system, which is explained in more detail in Example 3; and

5 Recording of an exemplary, manufactured according to the invention microfluidic system, which is explained in more detail in the embodiment 4.

Description of the components of in 1 arrangement shown: 101 - Microfluidic system, 102 Reservoir of the dispersed fluid, 103 Reservoir of the focussing fluid, 104 Integrated inflow of the dispersed fluid, 105 Integrated inflow of the focussing fluid, 106 Inflow channels - for the transmission of the focussing fluid (a part of a n = 7 nozzle set), 107 Channels - for the transfer of the dispersed fluid, 108 - nozzle mouth, 109 - Lower class, 110 - middle layer 111 Upper layer of the microfluidic system.

Description of the components of in 2 - 5 arrangements shown: 1 Integrated inflow of the focussing fluid, 2 Reservoir of the focussing fluid, 3 Resistive channel for transmitting the focusing fluid (a part of a nozzle set), 4 Upper layer of the microfluidic system.

The inflow channels of the focussing fluid are cuboidal and represent a two-dimensional (planar) equivalent of the outer capillary in an axisymmetric arrangement. To each nozzle are supplied two inflow channels of the focussing fluid. The hydraulic resistance - r - of the reservoir of the focussing fluid is significantly smaller than the hydraulic resistance - R - of a single inflow channel of the focussing fluid.

• • Verfahren zur Versorgung mit Fluiden von zwei oder mehr Düsen, durch ein Mikrofluidiksystem, bestehend in der Einführung in die Anordnung integrierter Zuflüsse, das heißt der Zuflüsse, die einen Set von zwei oder mehr Düsen versorgen; wobei:
• – Jede Düse in einem Düsenset besteht aus einem quaderförmigen Kanal, durch den das dispergierte Fluid übertragen wird, und aus einem Paar von quaderförmigen Widerstandskanälen, die das fokussierende Fluid übertragen; vorzugsweise befinden sich die das fokussierende Fluid übertragenden Widerstandskanäle an zwei Seiten des Kanals, durch den das dispergierte Fluid übertragen wird.
• – Der integrierte Zufluss ist im Reservoir des fokussierenden Fluids angebracht, d. h. in einem Raum mit Volumen V größer als das Volumen des einzelnen, quaderförmigen Widerstandskanals, durch den das fokussierende Fluid übertragen wird.
• – Im Rahmen eines Düsensets kennzeichnet sich jeder der das fokussierende Fluid übertragenden Kanäle durch gleichen hydraulischen Widerstand – R, und der Widerstand der Kanäle, die das fokussierende Fluid übertragen, ist bedeutend größer als der Widerstand des Reservoirs des fokussierenden Fluids – r, und der Widerstand der Düse selbst. Vorzugsweise beträgt das Verhältnis der Widerstände r/R 1/100 oder weniger.
• • Planares Mikrofluidiksystem bestehend aus mindestens 3 Schichten, von denen eine einen Zufluss des fokussierenden Fluids und einen Zufluss des dispergierten Fluids beinhaltet, wobei:
• – Die Zuflüsse des fokussierenden und des dispergierten Fluids sind integriert, d. h. ein Zufluss versorgt ein Set von zwei oder mehr Düsen;
• – Jede Düse in einem Düsenset besteht aus einem quaderförmigen Kanal, durch den das dispergierte Fluid übertragen wird, und aus einem Paar von quaderförmigen Widerstandskanälen, die das fokussierende Fluid übertragen; vorzugsweise befinden sich die das fokussierende Fluid übertragenden Widerstandskanäle an zwei Seiten des Kanals, durch den das dispergierte Fluid übertragen wird.
• – Der integrierte Zufluss ist im Reservoir des fokussierenden Fluids angebracht, d. h. in einem Raum mit Volumen V größer als das Volumen des einzelnen, quaderförmigen Widerstandskanals, durch den das fokussierende Fluid übertragen wird.
• – Im Rahmen eines Düsensets kennzeichnet sich jeder der das fokussierende Fluid übertragenden Kanäle durch gleichen hydraulischen Widerstand – R, und der Widerstand der Widerstandskanäle, die das fokussierende Fluid übertragen, ist bedeutend größer als der Widerstand des Reservoirs des fokussierenden Fluids – r, und der Widerstand der Düse selbst. Vorzugsweise beträgt das Verhältnis der Widerstände r/R 1/100 oder weniger.

In the exemplary embodiment explained here, the invention comprises:

• • A method of supplying fluids from two or more nozzles, through a microfluidic system, consisting in the introduction to the array of integrated tributaries, that is, the inlets supplying a set of two or more nozzles; in which:
• Each nozzle in a nozzle set consists of a parallelepiped channel through which the dispersed fluid is transferred, and a pair of parallelepipedic resistance channels which transmit the focusing fluid; Preferably, the resistive channels transmitting the focusing fluid are located on two sides of the channel through which the dispersed fluid is transferred.
• - The integrated inflow is mounted in the reservoir of the focussing fluid, ie in a space with volume V greater than the volume of the individual, cuboid resistance channel through which the focussing fluid is transmitted.
• In a nozzle set, each of the focusing fluid transmitting channels is characterized by the same hydraulic resistance - R, and the resistance of the channels transmitting the focusing fluid is significantly greater than the resistance of the focusing fluid reservoir - r, and the resistance Preferably, the ratio of the resistances r / R is 1/100 or less.
• Planar microfluidic system comprising at least 3 layers, one of which includes an inflow of the focussing fluid and an inflow of the dispersed fluid, wherein:
• The inflows of the focusing and the dispersed fluid are integrated, ie one inflow supplies a set of two or more nozzles;
• Each nozzle in a nozzle set consists of a parallelepiped channel through which the dispersed fluid is transferred, and a pair of parallelepipedic resistance channels which transmit the focusing fluid; Preferably, the resistive channels transmitting the focusing fluid are located on two sides of the channel through which the dispersed fluid is transferred.
• - The integrated inflow is mounted in the reservoir of the focussing fluid, ie in a space with volume V greater than the volume of the individual, cuboid resistance channel through which the focussing fluid is transmitted.
• In the context of a nozzle set, each of the focusing fluid transmitting channels is characterized by the same hydraulic resistance - R, and the resistance of the resistance channels transmitting the focusing fluid is significantly greater than the resistivity of the focusing fluid reservoir - r, and the resistance Preferably, the ratio of the resistances r / R is 1/100 or less.

Preferred embodiments of the invention

Example 1 - a 10-nozzle set

• – einem zentralen quaderförmigen Kanal mit charakteristischen Abmessungen 0,20 mm × 0,20 mm, durch den das dispergierte Fluid übertragen wird,
• – zwei quaderförmigen, das fokussierende Fluid übertragenden Widerstandskanälen 3, mit charakteristischen Abmessungen 0,20 mm × 0,20 mm, die symmetrisch, an beiden Seiten des Kanals, durch den das dispergierte Fluid übertragen wird, angebracht sind.

A three-layer, 10-nozzle set microfluidic system was constructed. Each layer is made of a 2 mm high polycarbonate plate. The example is shown in the picture ( 2 ). The visible in the recording reservoir of the focusing fluid 2 , which is located in the lower layer of the microfluidic system, has the dimensions 15 mm × 3.0 mm × 1.2 mm (width × height × depth) and is provided with a round-walled inflow tube 1 equipped with a diameter of 0.8 mm. Each of the nozzles in the 10-nozzle set consists of:

• A central cuboidal channel of characteristic dimensions 0.20 mm × 0.20 mm, through which the dispersed fluid is transferred,
• - Two cuboid, the focusing fluid transmitting resistor channels 3 , having characteristic dimensions of 0.20 mm × 0.20 mm, which are symmetrically mounted on both sides of the channel through which the dispersed fluid is transferred.

The volume of the focusing fluid reservoir -V in the above example is 54 microliters for a volume of a single focusing fluid-transmitting channel -v - equal to 2 microliters. The ratio of hydraulic resistances r / R is approximately 1/20000 ((1 x 0.04 ^{2/6 2} * 5) - see: the derivation of the formula for the ratio of the hydraulic resistances of the reservoir and the resistance channel.

Example 2 - a 6-nozzle set

• – einem zentralen quaderförmigen Kanal mit charakteristischen Abmessungen 0,20 mm × 0,20 mm, durch den das dispergierte Fluid übertragen wird,
• – zwei quaderförmigen, das fokussierende Fluid übertragenden Widerstandskanälen 3, mit charakteristischen Abmessungen 0,20 mm × 0,20 mm, die symmetrisch, an beiden Seiten des Kanals, durch den das dispergierte Fluid übertragen wird, angebracht sind.

A three-layer microfluidic system consisting of a 6-nozzle set was constructed. That in the recording ( 3 ) visible reservoir of the focussing fluid 2 , which is located in the lower layer of the microfluidic system, has the dimensions 10 mm × 0.35 mm × 0.8 mm (width × height × depth) and is provided with a round-walled inflow pipe 1 equipped with a diameter of 0.8 mm. The upper layer 4 The microfluidic system is made of a 2 mm high polycarbonate plate, two further layers are made of 0.8 mm high polycarbonate plates. Each of the nozzles in the 6-nozzle set consists of:

• A central cuboidal channel of characteristic dimensions 0.20 mm × 0.20 mm, through which the dispersed fluid is transferred,
• - Two cuboid, the focusing fluid transmitting resistor channels 3 , having characteristic dimensions of 0.20 mm × 0.20 mm, which are symmetrically mounted on both sides of the channel through which the dispersed fluid is transferred.

The volume of the focusing fluid reservoir -V in the above example is 3 microliters for a volume of a single resistive channel transmitting resistive fluid - v - equal to 0.4 microliters. The ratio of the resistances r / R of the reservoir of the focusing gas to that of a single resistance channel is about 1/100 (0.04 ² / 0.28 ² x 2).

Example 3 - a 25-nozzle set

• – einem zentralen quaderförmigen Kanal mit charakteristischen Abmessungen 0,20 mm × 0,20 mm, durch den das dispergierte Fluid übertragen wird,
• – zwei quaderförmigen, das fokussierende Fluid übertragenden Widerstandskanälen 3, mit charakteristischen Abmessungen 0,20 mm × 0,20 mm, die symmetrisch, an beiden Seiten des Kanals, durch den das dispergierte Fluid übertragen wird, angebracht sind.

A three-layer microfluidic system consisting of a 25-nozzle set was constructed. 4 ) visible reservoir of the focussing fluid 2 is complex. It consists of a pre-reservoir attached across all layers with dimensions of 6.8 mm × 5.8 mm × 3.0 mm (width × height × depth) and is equipped with a round-walled inflow pipe 1 equipped with a diameter of 2.8 mm. Subsequently, 0.8 mm wide channels are led, which divide the focusing fluid to the correct reservoir with dimensions of 36 mm × 0.35 mm × 0.8 mm (width × height × depth). The upper layer 4 The microfluidic system is made of a 2 mm high polycarbonate plate, two further layers are made of 0.8 mm high polycarbonate plates. Each of the nozzles in the 25-nozzle set consists of:

• A central cuboidal channel of characteristic dimensions 0.20 mm × 0.20 mm, through which the dispersed fluid is transferred,
• - Two cuboid, the focusing fluid transmitting resistor channels 3 , having characteristic dimensions of 0.20 mm × 0.20 mm, which are symmetrically mounted on both sides of the channel through which the dispersed fluid is transferred.

The volume of the reservoir of the focusing fluid - V is 10 in the above example Microliters at a volume of a single resistive channel transmitting the focussing fluid - v - equal to 0.7 microliters. The ratio of the resistances r / R is about 1/50 (2 × 0.04 mm ² / 0.28 mm ² × 2).

Example 4 - a 100 nozzle set

• – einem zentralen quaderförmigen Kanal mit charakteristischen Abmessungen 0,20 mm × 0,20 mm, durch den das dispergierte Fluid übertragen wird,
• – zwei quaderförmigen, das fokussierende Fluid übertragenden Widerstandskanälen 3, mit charakteristischen Abmessungen 0,20 mm × 0,20 mm, die symmetrisch, an beiden Seiten des Kanals, durch den das dispergierte Fluid übertragen wird, angebracht sind.

A nine-layer microfluidic system consisting of four 25-nozzle sets was constructed. That in the recording ( 5 ) visible reservoir of the focussing fluid 2 is complex. It consists of a pre-reservoir attached across all layers measuring 6.8 mm × 5.8 mm × 6.0 mm (width × height × depth) and has a round-walled inflow pipe 1 equipped with a diameter of 2.8 mm. Thereafter, 0.8 mm wide channels are passed which divide the focusing fluid to each of the 25 nozzle sets to the proper reservoir of dimensions 36mm x 0.35mm x 0.8mm (width x height x depth). The upper layer 4 The microfluidic system is made of a 2 mm high polycarbonate plate, the other layers are made of 0.8 mm high polycarbonate plates. Each of the nozzles in a 25-nozzle set consists of:

• A central cuboidal channel of characteristic dimensions 0.20 mm × 0.20 mm, through which the dispersed fluid is transferred,
• - Two cuboid, the focusing fluid transmitting resistor channels 3 , having characteristic dimensions of 0.20 mm × 0.20 mm, which are symmetrically mounted on both sides of the channel through which the dispersed fluid is transferred.

The volume of the focusing fluid reservoir -V in the above example is 10 microliters for a volume of a single resistive channel transmitting resistive fluid - v - equal to 0.7 microliters. The ratio of the resistances r / R is about 1/50 (0.04 mm ² / 0.28 mm ² ).

The embodiments of the invention presented above are in the introduction in the case of the delivery through the nozzles: a gas, for. As air, as the focusing fluids and water as the dispersed fluid explained. However, it will be understood by those skilled in the art that by forming the droplets of the disperse phase (liquid) suspended in the focusing phase (liquid), liquids can be conveyed by the described systems in an analogous manner. In general case, the process of the invention allows to form aerosols and emulsions characterized by a narrow size distribution and a productivity proportional to the number of nozzles in the set. A prerequisite for efficient emulsion formation is such an interphase voltage that arises upon contact of a hydrophobic fluid with a hydrophilic fluid (eg, water and oil).

(Approximate) Derivation of the ratios of the hydraulic resistances of the reservoir and the capillary

Hydraulic resistance of any conduit (channel) for laminar flows is given by the quotient of the pressure difference at ends of the conduit and the velocity of the volumetric flow (expressed in m ³ / s in the Si system). The law of Hagen-Poiseuille named after its creators can be described by the following equation: R _hyd = Δp / Q,

η

– Viskosität des zu übertragenden Fluids,

L

– Kanallänge,

A

– Kanalquerschnitt.

The hydraulic resistance rescaled to other parameters can also be expressed by the following equation: R _hyd ≡ ηL / A ² , where

η

Viscosity of the fluid to be transferred,

L

Channel length,

A

- Channel cross section.

γ

– Verhältnis der Kanalbreite zur Kanalhöhe,

O

– Korrektur (O/α-Wert stellt einen Einschätzungsfehler des Parameters α dar)

The relation between R _hyd and R _hyd * is linear, and the proportionality constant represents a geometric parameter α. For channels of rectangular cross-section, the parameter can be very closely approximated to the following expression ( NA Mortensen, F. Okkels, H. Bruus, Phys. Rev. E, 71, 2 (2005) ) are simplified: α = R _hyd / R _hyd * = α (C) = 22 / 7C - 65/32 + O (C - 18) ² ≈ 22 / 7C - 65/3 wherein, C (γ) = 8 + 4γ + 4 / γ22

γ

- ratio of the channel width to the channel height,

O

- correction (O / α-value represents an estimation error of the parameter α)

For example, for a channel with a square cross-section, the value of α is: α (16) ≈ 29, and for a channel with a rectangular cross-section with an aspect ratio equal to 2 (γ = 2), the value of α is: α (18) = 35

By comparing two channels, one with a width-to-height ratio of about 2, and second with a square cross-section, we obtain the following quotient in terms of the parameter α: α (18) / α (16) = 35/29 = 1.2

The equation for comparing the hydraulic resistances of the reservoir and the square-sectioned resistance channel having a square cross-section is as follows: R _hyd = Δp / Q = αR _hyd * = αηL / A ² R _hyd (reservoir) _hyd R _hyd (reservoir) = 35 _L L _rez / A ² _rez R _hyd (capillary) ≡ R _hyd (capillary) = 29ηL _kap / A ² _kap

The equation allowing to judge the ratio of the hydraulic resistances of the reservoir and the square-sectioned rectangular resistance channel is as follows: R _hyd (reservoir) / R _hyd (capillary) = 1.2 (L _rez / A ² _rez ) (L _kap / A ² _kap ) = = 1.2 (L _rez A ² _kap ) / (A ² _rez L _kap ) ≈ (A ² _cape / A ² _rez )

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• WO 1999/0300832 Al [0008]

Cited non-patent literature

• AM Gañán-Calvo, Phys. Rev, Lett. 80, 285, (1998) [0006]
• AM Gañán-Calvo, Appl. Phys. Lett. 86, 214101 (2005) [0008]
• NA Mortensen, F. Okkels, H. Bruus, Phys. Rev. E, 71, 2 (2005) [0037]

Claims (5)

Microfluidic system for supplying a nozzle set with fluids, comprising an integrated inflow ( 105 ) of the focussing fluid leading to a reservoir ( 2 . 103 ) of the focussing fluid, and n ≥ 1 pairs of inflow channels ( 3 . 106 ) of the focussing fluid beginning at the reservoir ( 2 . 103 ) of the focussing fluid and correspondingly lead to n nozzles, characterized in that the hydraulic resistance R of each of the inflow channels ( 3 . 106 ) of the focussing fluid is significantly larger than the hydraulic resistance r of the reservoir ( 2 . 103 ) of the focussing fluid, preferably 50 times greater, more preferably 100 times greater, and most preferably 10,000 times greater. Arrangement according to claim 1, characterized in that the cross-sectional area a of each of the inflow channels ( 3 . 106 ) of the focussing fluid is significantly smaller than the cross-sectional area A of the reservoir ( 2 . 103 ) of the focussing fluid is more preferably 50 times smaller, more preferably 100 times smaller, and most preferably 10000 times smaller. Arrangement according to any one of the preceding claims, characterized in that the longest cross-sectional dimension d of each of the inflow channels ( 3 . 106 ) of the focussing fluid is significantly smaller than the longest cross-sectional dimension D of the reservoir ( 2 . 103 ) of the focussing fluid is more preferably 50 times smaller, more preferably 100 times smaller, and most preferably 10000 times smaller. Arrangement according to any one of the preceding claims, characterized in that it is made of polycarbonate, polyethylene, polypropylene or another mechanically or thermally deformable polymer. Arrangement according to any one of the preceding claims, characterized in that n = 1, 2, 6, 10, 25 or 100.

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