EP1351766B1 - Device and method for dosing small amounts of liquid - Google Patents

Abstract

A microdosage device comprises a media reservoir used for accommodating a liquid to be dosed, a nozzle connected via a connecting channel to the media reservoir and adapted to be filled via said connecting channel with the liquid to be dosed, and a drive unit for applying, when actuated, to a liquid contained in the media reservoir and in the nozzle a force of such a nature that a substantially identical pressure will be exerted on said liquid contained in the media reservoir and in the nozzle. Flow resistances of the connecting channel and of the nozzle are dimensioned such that, in response to an actuation of the drive unit, a volumetric flow in the connecting channel will be small in comparison with a volumetric flow in the nozzle, said volumetric flow in the nozzle causing an ejection of the liquid to be dosed from an ejection opening of the nozzle.

Description

The present invention relates to devices and method for dosing small amounts of liquid, and in particular to such devices and methods which for simultaneous, precise dosing of small or smallest amounts of liquid from several parallel channels are suitable.

The precise dosage of fluid quantities is among other things in pharmaceutical and biotechnology research, For example, genomics, the high-throughput screening, combinatorial chemistry and the like, from significant importance. Such a dosage is for example necessary to use so-called microtiter plates (in English well-plate) with reagents. To such a Filling are currently different Devices and methods are known, of which the most common Air cushion pipettes, piston displacement pipettes with Valve control, piezoelectric pipettes and needle pipettes are. Typically, the devices mentioned are single-channel designed. You can partly but also in the grid too be arranged parallel channels. The highest reached Degree of parallelization currently stands at 384 channels some commercially available dosing volume devices above 0.5 μl.

When applying the above principles or devices for filling of microtiter plates but often occur one or more of the difficulties mentioned below on. Usually dosing volumes smaller than 500 nl are not delivered. This is especially true on air cushion pipettes too. In addition, the Accuracy of all available devices in the lower dosing range only insufficient, the error typically over 10%. Furthermore, with the common devices a high integration density, for example grid dimensions of less than 4.5 mm, can not be achieved due to the design, so that sometimes a serial processing done got to. Only with needle pipettes can also grid dimensions of 2.25 mm can be achieved. If the dosage is not in free jet takes place, e.g. with needle pipettes, can carryover or cross-contamination of the metered Liquids occur.

Known microdosing devices are disclosed in DE-A-19706513 and DE-A-19802368. These known devices are based on a functional principle in which a Acceleration to a liquid to be dosed within a pressure chamber is applied by a displacer. The pressure chamber has a fluid connection to an outlet opening and to a fluid reservoir. Thus follows at Actuating the displacement in these known devices a movement of the liquid through both the outlet opening as well as back into the reservoir.

From DE-A-19913076 is a microdosing device known, through which a plurality of microdroplets on a Substrate can be applied, where there is an entire dosing is applied with an acceleration. By This acceleration of the entire dosing head is inertia a relative acceleration between contained Fluid and dosing reached such that droplets ejected from respective nozzle openings of the dosing become.

Finally, WO 00/62932 discloses methods and devices for metered dispensing of the smallest quantities of liquid, where discharge amounts in a range of 0.1 nl to 100 ul are called. According to this document is one with an outlet opening capillary used to the at least one gas line connected via an outlet point is. About the capillary is a gas shock in the Gas line introduced so that in the capillary located between the opening point and the outlet opening Amount of liquid dosed out of the outlet opening becomes. This document also mentions the possibility the creation of a pipetting array using a Plurality of metering devices as described above are. Also in the dosing devices described in this document there is a reflux in the reservoir or in worst case may be air bubbles in the reservoir line ascend and clog those.

From the above disadvantages results the fact that the duration of filling a microtiter plate in general considered too high for the desired throughput becomes. This results in a high cost and partly also difficulties in the analysis the reaction products, if the reactions in the individual Start reservoirs of the microtiter plate with a time delay.

R. Zengerle, "Microsystems - Opportunities for Dosing Technology", Weighing + dosing 1/1996, pp. 10-15, are micropumps Known for Mikrotropfeninjektoren, in which by a by means of a piezo bending transducer driven membrane the Volume of a pumping chamber is changeable. An inlet opening and an outlet opening of the pumping chamber are provided. A pumping action can be achieved when the membrane is actuated be by either the inlet opening and the outlet opening are provided with a check valve or by a buffer is provided adjacent to the pumping chamber.

From DE 19648694 C1 is a bidirectional dynamic Micropump known that has a pumping chamber and an inlet and a drain for the pumping chamber with different Has flow resistance. Adjacent to the pumping chamber a membrane, wherein by suitable shaping of the drive pulse for the membrane, the conveying direction of the micropump is controllable.

From WO 97/15394 a plate is known which has a plurality has the same penetrating recesses. The recesses have to a surface of the plate towards a large opening and to the opposite surface towards a small nozzle opening. By exercising a Pressure on the large opening can create a liquid jet be ejected through the small nozzle opening.

Another metering device is known from WO 99/36176, the one liquid reservoir and one with the Liquid reservoir fluidly connected channel has. In opposite channel walls of the channel are Formed openings, so that by applying a pressure on one of the openings located between the openings Liquid can be dispensed.

Further, US-A-5943079 discloses an ink jet printhead known, in which in a printhead a nozzle, a reservoir area and a nozzle connecting the reservoir and the reservoir area Cavity are structured. Adjacent to the Cavity is provided a piezoelectric plate, wherein by applying a pressure signal, a vibrating part of the piezoelectric Plate can be vibrated, so that a pressure wave occurs in the cavity. If the Pressure wave reaches a nozzle opening of the nozzle is thereby causes an ink ejection. The reservoir area is further by a membrane-like structure of a damping chamber separated, which has a vent.

The object of the present invention is to devices and method for dosing small amounts of liquid to create a simple structure of a Microdosing device and also a simultaneous, precise dosage of small amounts of liquid allow multiple parallel channels.

This object is achieved by a microdosing device Claim 1 and a method for dosing small amounts of liquid solved according to claim 10.

The operating principle of the microdosing device according to the invention and the dosing method of the invention small amounts of liquid is based on two points, for a simultaneous application of reservoir and Nozzle or nozzle channel with a force, so that a substantially the same pressure on them, and on the other hand a sufficient separation of the reservoir and the nozzle from each other through the connecting channel. Such Separation is more effective the higher the fluidic Resistance of the connection channel in relation to the fluidic Resistance of the nozzle channel is. Due to the fluidic Separation according to the invention is the maximum in the nozzle contained volumes, wherein after the dosing this volume of dosing automatically stops.

The reservoir, the nozzle and the connecting channel are according to the invention preferably formed in a dosing head, wherein such a dosing preferably a plurality of Reservoirs, nozzles and connecting channels may have. To a drop ejection from the nozzle opening or the nozzle openings to cause one or more nozzles is inventively a driving force on the entire imprinted liquid contained in the dosing head, i. either the reservoir as well as the nozzle will be with the force applied. Therefore, and because of the fact that the pressure gradient via the connecting line is negligible, takes place According to the invention, no backflow into the reservoir.

In preferred embodiments of the present invention Both the reservoirs and the jets are in a grid arranged in the format of a microtiter plate equivalent. Furthermore, the reservoirs and the nozzles be arranged in a different grid, so that by a dosing a format conversion between the format of the reservoirs and that of the recipient Container, usually a microtiter plate, takes place. The used in the microdosing device according to the invention Dosing head can in a conventional known manner manufactured using micromechanical methods be made of, for example, silicon or plastic, for example, using an injection molding technique. In preferred embodiments, the drive means from a pneumatic or hydraulic Drive unit having a pressure chamber, the fast with a gas or a liquid as a buffer medium can be filled to the required force to apply the reservoirs and nozzles.

According to the invention are preferably the reservoirs and the the discharge end of the nozzles opposite end thereof formed in a surface of the dosing, so that the entire first side of the dosing head or dosing head substrate can be charged with the driving force, only those in the nozzle, i. the nozzle channel and the nozzle opening, contained liquid is discharged and the metering process stops automatically as soon as it contains Liquid was discharged. This principle allows it, on a spatial separation of the areas in which the nozzles or reservoirs are arranged to dispense, resulting in significantly higher integration densities can be considered as having devices that are driving Force only on the back nozzle areas, not however acts on the reservoirs.

The present invention thus provides devices and Processes with which liquids highly parallel, for example can be dispensed into a microtiter plate. Consequently the microdosing device according to the invention has a simple structure and still allows exact dosage, even in the realization of a highly integrated Dosing in which, for example, using 1536 nozzles should be dosed in parallel. According to the invention can such an exact dosage without the use of active or passive valves, as according to the state of Technique to be used partially, as both reservoir as well as nozzles are subjected to the force and the connection channel between them accordingly is designed.

The present invention thus constitutes an essential one Improvement of dosing technology in the nanoliter range, the one highly parallel and therefore much faster metering of reagents in microtiter plates. there The present invention allows a high degree of parallelization and integration density, for example 96, 384, 1536 or more doses simultaneously at a Pitch of 9.0 mm, 4.5 mm, 2.25 mm or less performed can be. In addition, the present allows Invention also adapt to formats outside the standard for microtiter plates. In addition, the present invention an extremely high accuracy of the dosage, the error in the dosing volume at typical Dosage amounts from 50 nl to 100 nl less than 5 nl. By the non-contact delivery in the free jet is also a Carryover of media excluded. As already mentioned could, with an appropriate interpretation the device reformatations are carried out in parallel, for example, from a 384 format to a 1536 format.

Furthermore, the present invention allows storage of Media in the dosing head, so that the step of the transfer from the storage unit that currently is typically a 96-well microtiter plate, for Dosing machines, which are currently arranged in parallel Air cushion pipettes or the like is, saved can be. Finally, in the inventive Device and the method according to the invention dosed Volume largely independent of the physical Properties of the fluids used. The present Invention also enables the construction of a microdosing device, in which the dosing easily exchanged is, so that the drive means, in the Usually more complicated than the dosing itself, for a Variety of different dosing heads are used can. This is particularly advantageous that the entire first surface of the dosing head with the force is applied, so that here also at different Arrangement of reservoirs and nozzles in different Dosing heads no adjustment is necessary.

The present invention is thus particularly suitable to get accurate quantities of fluids in microtiter plates, the one standardized outside dimension and a large number have juxtaposed reservoirs, leave. Such microtiter plates comprise, as stated above, a variety of reservoirs, such as 96, 384, 1536 or more, where the pitches of the reservoirs corresponding to 9 mm, 4.5 mm, 2.25 mm, etc. Depending on the density of integration, the volume of the Reservoirs approximately 100 μl, 20 μl, 4 μl, etc. In these reservoirs become chemical or biochemical reactions carried out and analyzed the reaction products. The possibility for precise filling of microtiter plates with given quantities of liquid is therefore an indispensable Prerequisite for carrying out quantitative analyzes when using the smallest amounts of liquid, the present Invention just this option advantageous offers.

In addition to the precise filling of the microtiter plate is also a fast, preferably simultaneous metered addition of reagents in all reservoirs of interest, as in general a high number of reactions in a microtiter plate be carried out simultaneously. It is advantageous when the entire process of filling and analysis The results can be automated so that per day several hundred microtiter plates can be processed and carried out a few thousand to one hundred thousand reactions can be. For this purpose, the present Invention due to their property of massively parallel and high-precision dosing of smallest fluid quantities in a special way, especially for the delivery of a Variety of different liquids in the different Reservoir of a microtiter plate.

Fig. 1

eine schematische Ansicht, teilweise im Querschnitt, einer erfindungsgemäßen Mikrodosiervorrichtung;

Fig. 2

ein Netzwerkmodell der in Fig. 1 gezeigten Mikrodosiervorrichtung;

Fig. 3A

ein verallgemeinertes Netzwerkmodell für das erfindungsgemäße Dosiersystem und Fig. 3B ein Netzwerkmodell für ein bekanntes Mikrodosiersystem;

Fig. 4

eine schematische Darstellung eines Ausführungsbeispiels einer erfindungsgemäßen Mikrodosiervorrichtung;

Fig. 5

eine Querschnittansicht eines weiteren Ausführungsbeispiels einer erfindungsgemäßen Mikrodosiervorrichtung;

Fig. 6

und 7 Draufsichten von Dosierköpfen, die bei einer erfindungsgemäßen Mikrodosiervorrichtung verwendbar sind;

Fig. 8A bis 8D

Querschnittansichten, die unterschiedliche Gestaltungen für Düsen bei der erfindungsgemäßen Mikrodosiervorrichtung zeigen;

Fig. 9A bis 9D

schematische Darstellungen, die unterschiedliche Gestaltungen des Verbindungskanals bei erfindungsgemäßen Mikrodosiervorrichtungen zeigen;

Fig. 10A bis 10D

schematische Draufsichten auf bei erfindungsgemäßen Mikrodosiervorrichtungen verwendbare Dosierkopfsubstrate bzw. Abschnitte derselben; und

Fig. 11A und 11B

schematische Querschnittansichten zur Veranschaulichung einer erfindungsgemäß verwendbaren Antriebseinrichtung.

Preferred embodiments of the present invention will be explained below with reference to the accompanying drawings. Show it:

Fig. 1

a schematic view, partially in cross section, of a microdosing device according to the invention;

Fig. 2

a network model of the Mikrodosiervorrichtung shown in Figure 1;

Fig. 3A

a generalized network model for the dosing system according to the invention; and FIG. 3B a network model for a known microdosing system;

Fig. 4

a schematic representation of an embodiment of a microdosing device according to the invention;

Fig. 5

a cross-sectional view of another embodiment of a microdosing device according to the invention;

Fig. 6

and Fig. 7 are plan views of dosing heads usable in a microdosing apparatus according to the present invention;

8A to 8D

Cross-sectional views showing different designs for nozzles in the microdosing device according to the invention;

Figs. 9A to 9D

schematic representations showing different configurations of the connection channel in Mikrodosiervorrichtungen invention;

10A to 10D

schematic plan views of applicable in microdosing invention Dosierkopfsubstrate or sections thereof; and

Figs. 11A and 11B

schematic cross-sectional views for illustrating a usable according to the invention drive device.

FIG. 1 shows a detail of a dosing head 2, the part of an embodiment of an inventive Microdosing is. In the dosing 2 are a Media reservoir 4 and a nozzle 6 formed with a are filled to be metered liquid 8. The media reservoir 4 and the nozzle 6 are via a connecting channel 10th fluidly connected to each other. The microdosing device further comprises a drive device, which in the in Fig. 1 illustrated embodiment, a pressure chamber 12, a housing 13 for the pressure chamber 12 and a device 14 for pressurizing the pressure chamber having. The device 14 may be a conventional pump or a compressed air valve with a corresponding supply line be to the pressure chamber 12. Further, in the illustrated Embodiment, a vent 16 for Venting the pressure chamber 12 is provided. The pressure generating device 14 and the vent 16 are connected to a control device 18 which controls the same, to eject droplets from the nozzle 6.

As can be seen in Fig. 1, the nozzle shown there 6 a nozzle channel 20 and a nozzle opening 22, wherein the nozzle channel 20 has a larger cross section than the Nozzle opening 22 has. The nozzle opening 22 opposite Opening of the nozzle channel can as an operating opening be designated. The nozzle opening 22 is dimensioned in such a way that the surface tension of the liquid the nozzle opening 22 a leakage of the same in the idle state prevented. The nozzle channel 20 is designed so that he completely filled with fluid due to the capillary force is.

As shown, the media reservoir 4 is on a first one Side of the dosing head 2, i. in a first Surface of the same formed, whereas the liquid delivery through the nozzle opening 22 on the opposite second side of the dosing. The herein as a nozzle designated unit is through the nozzle channel 20 and the Düsenausstoßöffnung 22 formed and provides a fluid Connection between the first surface 24 and the second opposite surface 26 of the dosing 2. The connecting channel 10 connects the media reservoir 4 and the nozzle 6 in the embodiment shown in Fig. 1 at an orifice portion 28 in the lower region of the nozzle channel 20th

FIG. 2 shows a network model of the dosing head shown in FIG. 1, where P _A denotes the pressure difference between the upper side 24 and lower side 26 of the dosing head 2, which is generated by the force applied by the drive device 12, 13, 14. 2, the resistance R _{2 represents} the flow resistance of the connecting channel 10. Through the junction of the connecting channel 28 in the nozzle channel 22, he nozzle channel (22) can be divided into three sections, each of which a flow resistance can be assigned. The flow resistance R ₁₁ is assigned to the section of the nozzle channel between the first side 24 of the dosing head 2 and the point of the junction of the connecting channel 10. The flow resistance R _{12 of} the nozzle channel is assigned to the portion between the point of the junction of the connecting channel 10 in the nozzle channel 20 and the nozzle opening 22. Finally, the flow resistance R ₁₃ is assigned to the nozzle outlet opening 22 itself. In Fig. 2, the fluidic interconnection of the above-described flow resistances and the interconnection of the same with the reservoir 4 and the generated pressure P _{A is} shown. This results in the illustrated fluidic network model, which behaves similar to a corresponding electrical network.

According to the invention, the flow resistance of the connecting channel 10 and the nozzle, i. of the nozzle channel 20 and the nozzle opening 22, designed such that upon application one located in the media reservoir and the nozzle Liquid 8 with such a force that a substantially identical pressure on those in the media reservoir and the In the nozzle located liquid is applied, a volume flow in the connection channel 10 small compared to a volume flow in the nozzle 6 is.

This situation can be achieved if the flow resistance R _{2 of} the connection channel 10 is large compared to the flow resistance of the nozzle channel between the first side 24 and the second side 26 of the dosing head 2, ie R ₁₁ + R ₁₂ + R ₁₃ . Furthermore, in the exemplary embodiment shown in FIG. 1, a sufficiently good dosing quality can already be achieved if the condition R ₂ >> R _{11 is} fulfilled. For the sake of illustration, reference is again made to FIG. 2, which represents the corresponding fluidic network. The condition R ₂ >> R ₁₁ causes despite a loading of the entire first side 24 of the dosing head 2 with a pneumatic pressure, for example by the drive means 12, 14 described above, the voltage across the connecting channel 10 applied pressure difference is negligible. The movement of the liquid in the connecting channel is thereby also negligible. The pressure difference between the first and the second side of the dosing thus only results in that the amount of liquid in the nozzle 6 is discharged through the nozzle opening 22 to the outside.

As mentioned above, an exact dosage can be achieved if the flow resistance R _{2 of} the connection channel is made significantly larger than the total resistance of the nozzle channel. In such cases, in which the connecting channel 10 at a distance from the first side 24 opens into the nozzle channel 20, so that a resistance R ₁₁ can be defined already fulfilling the condition R ₂ >> R ₁₁ leads to a sufficiently good result. It should be noted that, as regards the design of the resistors R ₁₁ and R ₂ , the greater the difference in resistance, the greater the bandwidth of the different liquids which can be metered with sufficient accuracy using a corresponding metering device.

With regard to the design of the resistors R ₁₁ and R ₂ , it should be noted that the metered volume depends on the ratio of the two resistors. If one selects R ₂ / R ₁₁ ≈ 10, then the dosed volume corresponds to the liquid volume contained in the nozzle with a systematic deviation of maximally 10%. This deviation is due to the fact that due to the pressure drop across the flow resistance R ₁₁ at the junction of the connecting channel in the nozzle, a lower pressure prevails than on the top, ie the first side of the dosing or in the reservoir. This results in a pressure difference across the connecting channel, the size of which depends on the ratio of the flow resistances R ₂ and R ₁₁ , wherein an additional volume flow in the connecting channel is induced in the direction of the nozzle opening by this pressure difference. This volume flow or flow also contributes to the metered volume. The exact height of this systematic deviation depends on the details of the specific design of the connecting channel and nozzle channel. The deviation can be minimized by skillful, geometric design of the channels, in particular at their confluence. However, the proportion of this induced flow in the total flow through the nozzle or the nozzle opening can be estimated independently of these geometric details with the value R ₁₁ / R ₂ upwards. Due to the additional flow through the connecting channel, the dosing volume thus increases to a maximum of the (1 + R ₁₁ / R ₂ ) times the volume of the nozzle channel.

However, since the above-described operation is reproducible and the ratio of the flow resistances does not depend on the fluid's fluid properties, the accuracy and serviceability of the metering device is not affected. The exact ratio of the flow resistances is therefore not essential as long as R ₁₁ <R ₂ . In summary, it should be noted that the ratio of the flow resistances causes a systematic error, which can be compensated in the preparation of the metering devices. On the other hand, it does not cause a statistical error that would affect the reproducibility of the metering device. With regard to a simple and accurate design of the metering device, it may be desirable in practice to set the metering volume as accurately as possible by the volume contained in the nozzle. In this case, it is favorable to choose R ₁₁ / R ₂ as small as possible or R ₂ / R ₁₁ as large as possible, for example R ₂ / R ₁₁ > 100. This leads to excellent fluidic decoupling of nozzle and reservoir during a dosing process and the metered volume corresponds to the nozzle volume with a maximum deviation of 1%.

FIG. 3A shows a generalized network model showing a microdosing device according to the invention, wherein in FIG. 3A the resistance R _{K represents} the fluidic resistance of the connection channel between nozzle and reservoir, while the flow resistance R _{D represents} the flow resistance of the entire nozzle consisting of the Resistance of the nozzle channel and the resistance of the nozzle opening represents. In turn, P _A denotes the static or dynamic pressure generated by the respective drive unit. In order to achieve that in the network model in FIG. 3A, a volume flow of the liquid in the connecting channel is negligible compared with the volume flow of the liquid in the nozzle channel, the resistance R _{K is} to be chosen large in comparison to the flow resistance R _D. The ratio of flow resistances to be chosen on an individual basis depends on the liquid to be dosed, again finding that the greater the difference in resistance, the greater the range of liquids that can be dosed with the same dosing device ,

In any event, by loading the reservoir and nozzle with such a force as to exert substantially identical pressure on the liquid in the reservoir and nozzle, the present invention ensures that there is no backflow through the communication passage. Such reflux is the case with known metering systems, as described, for example, in the abovementioned publications DE-A-19706513, DE-A-19802368 or WO 00/62932. For purposes of comparison, a network model as it applies to the metering devices shown in the above references is shown in Figure 3B. It can be seen that there is a backflow into the reservoir in any case at a pressurization PA, wherein the ratio of metered liquid flows back to the liquid flowing back into the reservoir of the ratio of the flow resistance R _D and R _K.

Referring again to Fig. 1, a dosing operation will now be described the microdosing device shown there described in more detail. The dosing head 2, which is usually a plurality of Reservoirs and nozzles, wherein in Fig. 1 because of sectional representation only a reservoir 4 and a nozzle 6 are shown, is first with the or filled with the liquids to be dispensed. This happens, by using, for example, commercially available pipetting machines the fluids in the reservoir (s) 4 are filled. The filling of the rest Lines in the dosing head, i. the connecting channel 10, the Nozzle channels 20 and the nozzle opening 22, via capillary forces from the relevant media reservoirs. As above has been mentioned, the nozzle and nozzle opening 22 is dimensioned such that leakage of the liquid from the nozzle both on page 24 and on page 26 through the Surface tension of the same at rest prevented is.

It should be noted that in the one shown in FIG Embodiment in which the nozzle 6 a larger cylindrical opening as a nozzle channel 20 above a has a small cylindrical opening as a nozzle opening 22, the volume of the nozzle 6 substantially through the larger bore is determined, whereas the flow resistance the nozzle essentially through the smaller hole is defined. This subdivision of the nozzle into two areas different diameter is for the functioning the dosing device according to the invention is not absolutely necessary but facilitates the design of the dosing, by a setting of the desired dosage possible regardless of the retention capacity of the nozzle orifice 22 against a hydrostatic pressure in the liquid, which occur during handling and transport can.

After complete filling of the nozzle, which is preferred Embodiments of the present invention By capillary forces, the dosing is 2 with a Drive unit connected, as shown in Fig. 1 schematically by the elements designated by the reference numerals 12 and 14 is shown. Using the pressure generator 14, for example by opening corresponding Pneumatic valves, then in the pressure chamber 12th produces an overpressure that is even on the entire first Side of the dosing acts, i. the media reservoir 4 and the nozzle 6 are from the first side with a in essentially the same pressure applied. Through this in the pressure chamber 12 prevailing overpressure is on the Liquid 8 in the dosing 2 exerted a force. As soon as acting on the liquid in the nozzle opening 22 Force is large enough to increase the surface forces of the liquid to overcome at the nozzle opening, the liquid begins to flow out through the nozzle opening 22. An afterglow of liquid from the reservoir 4 is hereby largely prevented, provided that the pressure difference between the two ends of the connecting channel 10 negligible or reproducible, which is the case when the Flow resistance of the connecting channel 10 and the nozzle channel designed according to the above explanations are. In any case, as stated above, the amount is a fluid flowing from the reservoir reproducible, even if the ratio of flow resistance of connecting duct and nozzle not big enough is to substantially prevent such after-flow.

If the flow resistance of the connecting channel is sufficiently high, compared to the flow resistance of the nozzle or compared to the resistor R ₁₁ , the liquid in the connecting channel remains substantially at rest, while liquid is ejected from the nozzle channel 20 through the nozzle opening 22.

In such a dosing process, the whole in the nozzle amount of liquid through the nozzle opening 22nd are discharged, without that in the connecting channel moving liquid moves. Thus, the metered Liquid quantity determined exactly by the geometry of the nozzle. The dosage of the liquid stops from even if the nozzle is completely empty.

By operating the drive device, as described, a fluid volume equal to the total volume of the nozzle 6, are metered out of the nozzle opening 6. however it is also possible to use only part of the Nozzle and defined by the geometry of the nozzle Expelling fluid through the nozzle orifice, while the liquid in the connecting channel is not or only slightly moved.

After the nozzle is completely or partially emptied, can the initial state after switching off the drive device alternatively restored by two options become. On the one hand, a venting of the pressure chamber take place, for example, by that shown in Fig. 1 Valve 16. Otherwise, the pressure generating device using so-called 3/2-way pneumatic valves be designed to actively aerate to allow the pressure chamber by switching the valves.

Is a venting device not provided or used the drive unit is pure switching valves, i. 2/2-way pneumatic valves, may be after switching off the pressure supply the overpressure caused by a gas flow through the Remove the nozzles.

Is the overpressure in the pressure chamber 12 sufficiently degraded, so fill the connecting channel 10 and the nozzle 6, i. the nozzle channel 20 and the nozzle opening 22 thereof, due to the capillary forces back out of the same with the same connected media reservoir, whereupon a renewed dosing can be carried out.

In the microdosing device according to the invention, it is to a clean break of the exiting liquid column the nozzle opening to achieve, advantageously, a sufficient to generate high pressure amplitude in the pressure chamber whose temporal change beyond beneficial within should be done in a very short time, so that a high dynamic the pressure change is achieved. Furthermore, it is in the design the dosing head and the drive unit favorable, when the liquid discharge within a short time, for example 10 milliseconds, completed while the fluid lines for the refills by capillary forces be designed so that this process very much slower, for example within 100 milliseconds. Thus, both effects are superimposed only insignificantly and the precision of the dosing volume is determined by the Capillary refilling not falsified.

Now having a micro-dosing device according to the present Invention and the operation of the same general In the following, embodiments will be described and specific embodiments thereof closer received.

In Fig. 4 is a schematic representation of an inventive Microdosing shown to the simultaneous application of microdroplets to appropriate Places 30 of a microtiter plate 32, which is a conventional Grid of reservoirs 30 may have, suitable is. As shown in FIG. 4, the dosing head 2 the microdosing in the top 24 thereof a plurality of media reservoirs 4. At this point It should be noted that in Fig. 4, only in the top 24 formed Medienreservoire 4, but not the respective associated, also formed in the top 24 ends the nozzles are shown. Finally, the in Fig. 4 shown microdosing a drive device 40, for example, have a structure can, as explained below with reference to FIG. 5 becomes.

With the embodiment shown in Fig. 4 can simultaneously a plurality of microdroplets, for example be applied to a microtiter plate 32 by at the same time a plurality by means of the drive means 40 actuated by fluid reservoirs 4 with associated nozzles become. Furthermore, as can be seen from Fig. 4, the dosing 2 preferably easily and automatically exchangeable, so that together with the same drive means 40 different dosing heads or dosing head substrates can be used as long as the outside dimensions the same match or the drive device is designed to be different with dosing head substrates Exterior dimensions cooperate.

In Fig. 5 is a cross-sectional view of an inventive Microdosing device with a plurality of media reservoirs 4, nozzles 6 and connecting channels 10, which in one Dosierkopfsubstrat 2 are formed shown. The drive device in turn includes a pressure chamber 12 with a corresponding housing 13. The housing can in suitable Be configured to attach to the To enable dosing head substrate 2, or the use allow a replaceable dosing 2. In the Pressure chamber 12, a diffuser 40 is provided for securing a uniform distribution of pressure over all reservoirs 4 and nozzles 6 are used. The one shown here pneumatic realization of the drive unit further comprises fast switching valves 42 and compressed air supply lines 44.

In the pressure chamber 12 can by fast switching Valves 42 are produced with high dynamics overpressure, through which a driving force on the fluids in is transferred to the dosing head, i. at the same time on the located in the media reservoirs 4 and the nozzles 6 Liquids.

6 is a plan view of a section of a dosing head, for parallel delivery of reagents in a 1536 microtiter plate can be used, shown wherein 24 media reservoirs 4, connection channels 10 and associated nozzles 6 are shown. To a dosage into a 1536 microtiter plate are included the embodiment of a Dosierkopfsubstrats shown in Fig. 6 both the reservoirs 4 and the nozzles 6 with a pitch of a = 2.25 mm, i. in a grid of 2.25 x 2.25 mm, arranged. Furthermore, the connection channels 10a has a shape as referred to below is explained on Fig. 9A.

It is clear that according to the invention a micro-dosing a almost any number of media reservoirs and nozzles in FIG. 7, an exemplary dosing head with 96 media reservoirs and associated nozzles with exemplary dimensions is shown.

It should be noted that according to the invention not each one nozzle must be assigned a media reservoir, but here essentially freedom of choice exists that one or more media reservoirs provided can be connected to one or more nozzles can be, with a respective media reservoir over several Connecting lines to be connected to a nozzle can, a media reservoir over several connecting lines can be connected to multiple nozzles, and a nozzle over several connecting lines with several media reservoirs may be connected, as later with reference to FIGS. 10A to 10D will be explained in more detail. Furthermore, in the inventive Microdosing device both the reservoirs as well as the nozzles arranged in a different grid be, so that by the dosing a format conversion between the format of the reservoirs and that of the receiving container takes place. This can be a conventional Pipetting device for filling a microtiter plate be used even if the pipetting device a different grid than the microtiter plate to be filled having.

With reference to FIGS. 8A to 8D, exemplary embodiments of nozzles formed in the dosing head of a microdosing device according to the invention will now be explained. The simplest embodiment of a nozzle 6a is shown in Fig. 8A, where the entire nozzle consists of a single channel of constant diameter. In this nozzle 6a, depending on the height at which the connecting channel 10 opens into the nozzle 6a and as it is dimensioned, the resistors R ₁₁ and R ₁₂ , which have been explained above with reference to FIG. 2, can be influenced within certain limits ,

The nozzle 6 shown in Fig. 8B corresponds to the above with reference 1 illustrated nozzle, wherein by the subdivision the nozzle 6 in two sections different Diameter above or below the confluence point of the connection channel 10 due to the use of two Diameter and two lengths reached a variability which is a separate sizing of volume, flow resistance and holding capacity of the nozzle easier.

In Fig. 8C, a nozzle 6b is shown, which is divided into three sections is divided. Such a subdivision may under circumstances be advantageous if not only the dosing volume, but also the shape and / or dynamics of the ejected Beam are of importance.

Finally, Fig. 8D shows a conical nozzle 6c.

With regard to the design of the nozzle remains final determine that it is possible to have both the nozzle discharge opening as well as the same opposite opening and the nozzle channel connecting the openings not circular, but in any shape. Besides The diameter of the nozzle channel may be different than vary as a function of depth in FIGS. 8B to 8D.

Various design possibilities for the connecting channel, the interior reservoirs and jets are in the Figs. 9A to 9D are shown. Depending on the application, the connection channel both in terms of its course as also be adapted in terms of its diameter. In FIG. 9A shows a channel 10a which is at the top of the Dosing head is open. Such a channel is at the in FIGS. 6 and 7 show embodiments of a dosing head used. This possibility of channel design allows also the operation of the microdosing according to the described principle and has advantages in terms a simple production and the advantage that Gas inclusions easily escape in the connecting channel can.

In the example shown, a circular reservoir 4 through a rectangular connection channel 10a with the nozzle 6, wherein the reservoir and the connecting channel have the same depth to a drainage of the reservoir to the ground to ensure.

Fig. 9B shows a sectional view of a dosing head substrate in the plane of the substrate. In the section shown is a media reservoir 4 and a nozzle 6 to recognize the over a curved channel 10B are interconnected. In addition to the non-rectilinear course shown in Fig. 9B of the channel 10B are other, any gradients possible, where in particular meandering courses are used can increase the flow resistance between Media reservoir and nozzle to realize.

The connecting channel between the media reservoir and nozzle can furthermore have any cross sections and does not necessarily have be rectangular. Finally, the Expand or contract the cross-section in the course of the channel, also including, for example, two or more connection channels arranged between the same reservoir and the same nozzle could be.

Such a configuration is shown in Fig. 9C, at the channel is formed by three subchannels 10c. About that In addition, the channel does not have to be parallel to the surface of the Dosing head run, but can within the dosing have any course, with an oblique extending channel 10d is shown in Fig. 9D. Regarding of the channel is only to be noted that the same no establishes a direct connection to the bottom of the dosing head, but only over the nozzle. In addition, must the flow resistance of the connecting channel be greater as the flow resistance of the nozzle.

In Figs. 10A to 10D are different possibilities for arranging the fluidic components of the media reservoir, Connecting channel and nozzle in the dosing of the invention Microdosing represented. First is determine that not all mounted in a dosing Elements, such as media reservoirs, that must have the same dimension. The same applies to the Connecting channels and nozzles. In particular, nozzles that contain different volumes on the same dosing head be housed. Furthermore, there are design options in that the number of nozzles and reservoirs do not have to be the same, but that respectively several nozzles connected to one or more reservoirs or multiple reservoirs with one or more Nozzles can be connected.

Fig. 10A shows schematically a Dosierkopfabschnitt, at a media reservoir 4 via four connecting channels 10th is connected to four nozzles 6. In Fig. 10B, there are two Media reservoir 4 via a respective connecting channel 10th connected to a nozzle 6. In this example is a blending from fluids originating from the two reservoirs 4 before each dosing within the nozzle 6 possible. In addition, in an extreme case, an arrangement possible, in which all nozzles 6 from a single reservoir 4a, as shown in Fig. 10C.

Regardless of whether the number of nozzles and reservoirs can in any case by the dosing a Format conversion done. This means that the distance of Nozzles to each other and the distance of the reservoirs to each other can be different. An example of such an arrangement with wide intervals between reservoirs 4 and narrow spaces between nozzles 6 is shown in FIG. 10D, In this example, each nozzle 6 is connected via a connection channel 10 connected to an associated media reservoir 4 is.

In Figs. 11A and 11B is an alternative embodiment a drive device used in the invention can be represented.

Like the schematic shown in Figs. 11A and 11B Partial cross-sectional views can be seen, the dosing head the one described above with reference to FIG. 9A Construction with regard to media reservoir 4, channel 10a and nozzle 6 on. In contrast to the reference to FIGS. 1 and 5 described embodiments, however, is now the necessary for dosing force by means of a system fluid 46 located on the in the media reservoir 4 and the nozzle 6 exercised to metered liquid. It may the system liquid 46 with the liquid to be dosed must not be miscible and must be on the surface of the dosing have a negative surface energy, i. she must not be drawn into the nozzle by capillary forces. As shown in FIGS. 11A and 11B, a piston 48 is provided to force in the direction of arrow 50 on the System liquid 46 exercise. Alternatively, any one Other displacer be provided by the one such force on media reservoir and nozzle is exercisable that in them a substantially identical pressure condition is produced. About the system fluid 46 is the force exerted on the liquid to be dosed, whereupon the Dosing takes place. In Fig. 11B is the microdosing device after the discharge of the desired amount of liquid represented, wherein this amount of liquid through the displaced volume is determined. As seen in Fig. 11B is the system liquid 46 does not penetrate into the nozzle opening 22 and is not affected by capillary forces in pulled the same. Following the ejection of the desired Amount of liquid is the displacer or piston 48 returned to the starting position, wherein the hydrophobic System liquid 46 again by capillary forces the nozzle is displaced. This will change the original state, as shown in Fig. 11A restored.

As is clear from the above explanations, is according to the invention the metered volume from the volume of the nozzle, either only the nozzle channel or the nozzle channel and the nozzle opening, determined and is essentially independent of the Fluid properties. In this case, the present invention allows the exact delivery of, for example, about 50 nl in one single dosing with a suitable design of the channels and openings.

Although above preferred embodiments of the present Invention have been explained, it is clear that more Modifications and changes are possible. For example, alternative drive means used to be a driving force on the liquid impress. In addition to the described application of a homogeneous, pneumatic or hydraulic pressure in the area The first side of the printhead may also be under vacuum be applied to the second side of the dosing head, to suck the liquid out of the nozzle opening. In turn alternatively, a volume displacement of liquid can occur the first surface of the printhead, wherein a Example of such volume displacement by referring The embodiment described in FIGS. 11A and 11B using the system fluid 46. Furthermore, electrostatic or electromagnetic Forces that act directly on the liquid, or too any other forces that directly or indirectly affect the Liquid act, be used. To operate the Microdosing device required force can be applied to electromagnetic Ways are applied, if the to be dosed Liquid an electric charge or sufficient Possesses dipole moment. In such a case can by applying suitable electromagnetic fields between dosing head and receptacle, i. usually the microtiter plate, a force on the fluid towards the microtiter plate be exercised. The dosing process then begins once the electromagnetic force is the surface forces at the nozzle opening overcomes.

It needs no special mention that the several Reservoirs of the dosing head used in the invention filled with identical or different liquids can be so that the simultaneous delivery of the same or different liquids is possible. Further it is clear that the dosing heads used according to the invention produced by any conventional method can be. For example, the dosing head micromechanical be made of silicon. Alternatively come other known methods, such as micro injection molding, hot stamping or those methods where individual layers are glued or laminated, in question.

The metering device according to the invention can be used either as a metering device for the delivery of a through the geometric Volume of the nozzle channel predefined amount of liquid operated, or as a device with a smaller, but variable volume. In the first case, the driving force, which acts on the liquid, so long maintained until the entire contained in the nozzle Amount of liquid is ejected through the nozzle opening. The dosage stops in this case by itself, because due the vanishing pressure gradient across the connection channel no liquid is supplied. In the second case is impressed by the drive device, driving Force off before the liquid from the nozzle completely ejected.

The metered amount of fluid can therefore either by the design, namely by the volume in the nozzle, or by the duration and the course of the drive unit be applied applied driving force. In the first case, the metered amount of liquid in essential regardless of the physical properties the liquid, e.g. Viscosity and surface tension. In the second case, the metered volume of affected by these parameters. It is therefore recommended in the last case to perform a calibration to to achieve an exact dosage, since the dosage of different liquids with different viscosities takes different lengths. These different Duration must be considered, if not the entire nozzle volume is being dosed while being subordinate Meaning is when the total nozzle volume is metered out is, so that the dosing stops by itself, as soon as the entire liquid corresponding to the predefined Volume was ejected.

Claims (15)

1. Microdosage device comprising:

   a media reservoir (4) used for accommodating a liquid to be dosed (8), which has a media reservoir opening;

   a nozzle (6) with a nozzle channel (20) having an ejection opening (22) and an actuating opening, the nozzle (6) being connected via a connecting channel (10) to the media reservoir (4) and adapted to be filled via said connecting channel (10) with the liquid to be dosed (8); and

   a drive unit for concurrently applying, when actuated, via the media reservoir opening and the actuating opening, to a liquid (8) contained in the media reservoir (4) and in the nozzle (6) a force of such a nature that a substantially identical pressure will be exerted on said liquid contained in the media reservoir (4) and in the nozzle (6),

   wherein the flow resistance of the connecting channel (10) is greater than the flow resistance of the nozzle (6), and wherein the flow resistance of the connecting channel (10) is greater than the flow resistance of the nozzle channel (20) between a point at which the connecting channel (10) leads into the nozzle channel (20) and a point at which the force is applied to the liquid in the nozzle channel (20), so that, in response to an actuation of the drive unit, a volumetric flow in the connecting channel (10) will be small in comparison with a volumetric flow in the nozzle (6), said volumetric flow in the nozzle (6) causing an ejection of the liquid to be dosed (8) from an ejection opening (22) of the nozzle (6).
2. Microdosage device according to claim 1, comprising a dosing head (2) in which the media reservoir (4) and the nozzle (6) are formed, wherein the actuating opening as well as the media reservoir opening are formed in the same surface (24) of the dosing head (2).
3. Microdosage device according to claim 2, wherein the drive unit comprises a pressure generation means (12, 13, 14) for simultaneously applying a substantially uniform pressure to the media reservoir opening and the actuating opening.
4. Microdosage device according to claim 3, wherein the drive unit is provided with a pressure chamber (12) which is adapted to be filled with a buffer medium, the buffer medium being adapted to be used for applying the pressure to the media reservoir opening and the actuating opening.
5. Microdosage device according to one of the claims 1 to 4, which comprises multiple nozzles and one or a plurality of media reservoirs, wherein the drive unit is configured for actuating said multiple nozzles, and wherein each of said multiple nozzles is in fluid connection with one or a plurality of media reservoirs through one or a plurality of connecting channels.
6. Microdosage device according to one of the claims 1 to 5, which comprises multiple media reservoirs (4) and one or a plurality of nozzles (6), wherein each media reservoir is in fluid connection with one or a plurality of nozzle openings through one or a plurality of connecting channels.
7. Microdosage device according to claim 5 or 6, wherein said multiple nozzles (6) and/or said multiple reservoirs (4) are arranged in a raster which corresponds to the format of a well-plate (32).
8. Microdosage device according to claim 7, wherein multiple media reservoirs (4) are arranged in a first raster, and wherein multiple nozzles (6) are arranged in a second raster, so that a change of format takes place between said media reservoirs and said nozzles.
9. Microdosage device according to one of the claims 1 to 8, wherein the nozzle (6) and the connecting channel (10) are implemented such that the nozzle (6) will be filled from the media reservoir (4) via the connecting channel (10) due to capillary forces and without any actuation of the drive unit.
10. Method for dosing small amounts of liquid, said method comprising the following steps:

    filling at least one nozzle (6) having a nozzle channel (20) with an ejection opening (22) and an actuating opening via a connecting channel (10) with a liquid to be dosed (8) from a media reservoir (4) having a media reservoir opening, said connecting channel (10) establishing a fluid connection between said nozzle and said media reservoir (4);

    concurrently applying, via the media reservoir opening and the actuating opening, to the liquid (8) contained in the media reservoir (4) and in the nozzle (6) a force of such a nature that a substantially identical pressure will be applied to the liquid (8) contained in the media reservoir (4) and in the nozzle (6),

    wherein the flow resistance of the connecting channel (10) is greater than the flow resistance of the nozzle (6), and wherein the flow resistance of the connecting channel (10) is greater than the flow resistance of the nozzle channel (20) between a point at which the connecting channel (10) leads into the nozzle channel (20) and a point at which the force is applied to the liquid in the nozzle channel (20), so that the volumetric flow in the connecting channel (10) will be small in comparison with the volumetric flow of the liquid in the nozzle (6) so as to eject an amount of the liquid to be dosed from an ejection opening (22) of the nozzle.
11. Method according to claim 10, wherein the step of filling comprises a step of filling the nozzle (6) on the basis of capillary forces in the connecting channel (10) and in the nozzle (6).
12. Method according to claim 10 or 11, wherein the step of applying a force to the liquid contained in the media reservoir (4) and the nozzle (6) comprises the step of simultaneously applying a substantially identical pressure to the media reservoir opening and the actuation opening.
13. Method according to claim 10 or 11, wherein the step of applying a force to the liquid contained in the media reservoir (4) and in the nozzle (6) comprises the step of causing a volume displacement at the media reservoir opening and the actuation opening.
14. Method according to claim 10, or 11, wherein the step of applying a force to the liquid contained in the media reservoir (4) and in the nozzle (6) comprises the step of applying an electric or a magnetic field.
15. Method according to one of the claims 10 to 14, wherein the step of filling comprises the step of filling multiple nozzles (6) with different liquids from multiple media reservoirs (4), and wherein the application step comprises the step of simultaneously applying a force to said multiple nozzles (6) and said multiple media reservoirs (4) so that different liquids will be ejected simultaneously through he nozzles (6).

Images