WO2003018197A1

WO2003018197A1 - Micro-dispenser and pre-concentration method

Info

Publication number: WO2003018197A1
Application number: PCT/EP2002/008651
Authority: WO
Inventors: Jürgen SCRIBA; Christoph Gauer
Original assignee: Advalytix Ag
Priority date: 2001-08-22
Filing date: 2002-08-02
Publication date: 2003-03-06
Also published as: DE10141148B4; DE10141148A1

Abstract

The invention relates to a micro-dispenser for the production of a pre-concentration of charged particles in a liquid, comprising a main tank for receiving the liquid, a smaller pre-concentrate tank for receiving the pre-concentrated liquid, a channel element for connecting the main tank and the pre-concentrate tank and means for applying an electric field in a direction between the main tank and the pre-concentrate tank. The invention also relates to a multiple dispenser comprising several inventive micro-dispensers, and to a pre-concentration method for charged particles able to be carried out using the inventive devices.

Description

Microdispenser and preconcentration method

The invention relates to a microdispenser and a multiple dispenser for generating a preconcentration of charged particles in a liquid and a method for preconcentration.

In molecular biology, chips with spots of certain oligonucleotide sequences prepared in a defined manner are often used in order to load them with a sample of unknown composition. The hybridization reaction of those spotted on this chip, i. H. Known oligonucleotide sequences with the corresponding counterparts in the sample are then generally detected using optical methods such as fluorescence analysis. For example, when examining DNA (deoxyribonucleic acid), a fluorescent signal on a specific spot indicates the presence of the complementary DNA in the sample being examined.

Typical chip dimensions of such microarrays today are in the range of a few cm ² , the size of the individual spots is approximately 100 μm. When the chip is loaded with sample liquid, the entire chip is usually flooded with this sample. The chip is generally loaded with a small volume (approx. 10-100 μl) of sample liquid. Then he is covered with a cover slip and z in a water bath. B. incubated overnight at a suitable temperature to allow hybridization of the DNA fragments of sample and chip. Driven by diffusion, the sample molecules in the liquid migrate to the target molecules at the spots and bind there. The slow diffusion significantly limits the speed of the hybridization. During the incubation, e.g. B. is carried out for about 16 hours, the DNA molecules cover only a few millimeters. In such an arrangement, a spot on the chip can only interact with the sample volume in the immediate vicinity. The concentration of DNA in the sample must therefore be relatively high in order to ensure that the DNA molecules in the solution have the opportunity to interact with all spots on the chip.

In the case of a large amount of sample, the concentration of the oligonucleotides in the sample liquid is inevitably very low in view of the limited starting material. Accordingly, the reaction kinetics between the molecules in the sample liquid and the molecules on the chip are not optimal. This could only be avoided by significantly increasing the sample concentration, which in turn is problematic due to the high costs for the sample substance. To increase the concentration z. B. centrifuges are used, which requires an additional complex process step in which the sample liquid has to be reloaded an additional time. Accordingly, it would be desirable to have a device which makes it possible to enable a rapid and reliable hybridization reaction despite a possibly small amount of starting material.

It is the object of the present invention to provide an apparatus and a method with which an accurate dosing of the smallest amounts of liquid of high concentration is precisely possible at a desired location. This object is achieved with a microdispenser with the features of claim 1, a multiple dispenser with the features of claim 17 and a method with the features of claim 22. An advantageous use is the subject of claim 23. The respective subclaims are directed to advantageous configurations.

The microdispenser according to the invention has a main reservoir for receiving the liquid. Furthermore, a preconcentrate reservoir is provided which has smaller dimensions than the main reservoir and serves to hold the preconcentrated liquid. The reservoirs are connected to one another by a channel element. Means are also provided to generate an electric field in the direction between the main reservoir and the preconcentrate reservoir.

The microdispenser according to the invention can consist of different materials. However, the microdispenser according to the invention is preferably designed and dimensioned such that it is suitable for integration into or on a chip or comprises a chip. Such an embodiment is compact and z. B. easily manufactured using techniques from semiconductor technology.

For the purposes of the present application, the general term “chip” encompasses both the preferred embodiment in or on a solid-state chip made of crystalline material and structures made of other materials, for example plastic. Crystalline materials can be, for example, LiNbO ₃ or quartz his.

The main reservoir can be manually or with the help of e.g. B. a pipetting robot can be filled with a liquid, the charged particles, for. B. DNA molecules. The liquid is distributed in the main reservoir, channel element and preconcentrate reservoir. With typical dimensions of a corresponding chip, the microdispenser according to the invention is suitable, for. B. for the concentration of 1 to 10 ul amounts. If necessary, the distribution from the main reservoir to the preconcentrate reservoir is supported by the capillary action of the channel element. With the help of the means for applying an electrical field, an electrical generated field. For example, for pre-concentration of DNA fragments that are negatively charged, the electric field is generated such that the positive electrode of the field generating means is on the side of the pre-concentrate reservoir and the negative electrode on the side of the main reservoir. Similar to electrophoresis, the negatively charged particles are drawn towards the positive electrode and collect in the preconcentrate reservoir. In this way, a preconcentration is achieved, the strength of which depends on the applied electric field.

The liquid can then be defined from the preconcentrate reservoir and, with a precise preconcentration for further processing, e.g. B. be applied to an analysis chip with corresponding examination spots.

In a special embodiment of the microdispenser according to the invention, a chip is used which has two opposite main surfaces. The pre-concentrate reservoir is a small cavity with an opening to one of these major surfaces. The main reservoir is a larger cavity with a larger second opening to the other main surface. The channel element is formed by a capillary between the preconcentrate reservoir and the main reservoir.

In this advantageous embodiment, the microdispenser is designed to connect the two main surfaces within a chip. Such a microdispenser can be filled very easily through the larger opening of the main reservoir and allows precise localization of the preconcentrated liquid through the small opening of the preconcentrate reservoir. The microdispenser of such an embodiment can be connected directly to an element for further processing, onto which precise amounts of the pre-concentrated liquid can be discharged. The pre-concentrate reservoir is emptied e.g. B. with the help of an air blast, using piezoelectric methods or thermally, for. B. by heating the chip, preferably on the channel between the main and preconcentration reservoir. Such a microdispenser can also be made of plastic or comprise plastic components. To generate the electric field, electrodes are provided which generate an electric field between the main reservoir and the preconcentrate reservoir. Such electrodes are advantageously provided on the side of the main reservoir or preconcentrate reservoir remote from the capillary and can be contacted from outside the chip. Such electrodes are easy to connect to a voltage source and ensure optimal alignment of the electrical field between the main reservoir and the pre-concentrate reservoir.

In a particularly advantageous development, the larger opening, which is located in the main reservoir, is designed in a funnel shape, so that simple loading from the outside is possible.

A microdispenser which has a volume of the main reservoir of 1 to 10 μl and / or a volume of the preconcentrate reservoir of 5 to 50 nl can be used particularly advantageously. There are characteristic dimensions of the reservoirs in the range from 100 μm to 1 mm, which, for. B. in micro-laboratory applications in the sense of "lab-on-the-chip" technology are easy to handle and compatible. A particularly precise preconcentration and application is made possible.

A microdispenser integrated in a chip is compact and enables simple production using techniques from semiconductor technology. In another embodiment, however, the microdispenser is not integrated in a chip and is e.g. B. made of plastic. In such an embodiment, the electrodes are e.g. B. provided on the outer walls of the main or preconcentrate reservoir.

Advantageously, in the embodiments described above, the channel element has smaller lateral dimensions than both the preliminary and the main reservoir in order to improve the charge separation function and to improve the distribution of the liquid when filling the microdispenser due to the capillary action of the thin channel element.

The embodiments described above can also perform the function of a micropipette. The liquid can be sucked up like a pipette. The above-described embodiments of the microdispenser according to the invention can, for. B. with the help of an xy actuator over a micro-titer plate to fill their individual reaction surfaces.

In a further embodiment of the microdispenser according to the invention, a substrate or chip, in particular a solid state chip made of crystalline material, is provided, on one main surface of which partial areas are formed which have wetting properties that differ from the surrounding surface in such a way that a liquid preferably differs thereon staying. These areas form the main reservoir, the preconcentrate reservoir, and the channel element. The area of the main reservoir is larger than the area of the preconcentrate reservoir. The connecting channel element has a smaller lateral extension in the direction perpendicular to the connection of the main reservoir to the preconcentrate reservoir than the extensions of the reservoirs.

A liquid that is applied to the surface of the main reservoir is distributed over the main reservoir, the preconcentrate reservoir and the channel element. Because of the wetting properties that result in the liquid preferably being on the reservoir surfaces and the channel element, the liquid does not generally leave these surfaces. It is held together by the surface tension on these surfaces without flooding the surrounding surface. No channels or trenches are required to locate the fluid. The liquid does not leave the reservoirs and the channel element without the action of external force.

Such an embodiment of the microdispenser according to the invention is particularly easy, for. B. with lithographic processes and coating technologies, as are known from semiconductor technology, or z. B. with a stamp technique. No etching processes or layer structures are necessary. Due to the planar design, integration into other chip-using technologies is easily possible. Contacting with flat electrodes is very easy feasible. Such a microdispenser according to the invention can easily be combined with other chip components, as are already used today in so-called “lab-on-the-chip” technologies, in order to examine small amounts of liquid in a special biological nature (see, for example, BO Müller, Laborwelt 1 / 2000, pages 36ff.).

The different wetting properties can e.g. B. can be realized by an appropriate coating either of the preferred lounge area or its surroundings. For example, hydrophilic or hydrophobic areas can be defined. Are the macromolecules to be examined e.g. B. contained in aqueous solution, the preferred location is chosen so that it is more hydrophilic than the surrounding surface. This can be achieved either by hydrophilic coating of the preferred area or by a hydrophobic environment. A hydrophobic environment can e.g. B. can be realized by a silanized surface. The wetting properties can also be modulated by microstructuring, as is the case with the so-called lotus effect, which is based on different roughness of the surfaces and thus causes different wetting properties. Such roughness modulation can e.g. B. be obtained by microstructuring the corresponding surface areas, for. B. by chemical treatment or ion irradiation. The production of areas with different wetting properties is simple and inexpensive by using already known lithographic processes and / or coating technologies.

The channel element can be a single surface that connects the main reservoir and the pre-concentrate reservoir. In another embodiment, it is provided that the channel element comprises a plurality of essentially parallel strips which connect the main reservoir and the pre-concentrate reservoir to one another and have the wetting properties described above for the channel element. Between the individual strips of a channel element designed in this way there are surfaces which have similar wetting properties as the surfaces of the surroundings of the preconcentrate reservoir, the main reservoir and the channel element. A quantity of liquid which touches two or more such strips of a channel element at the same time will mainly wet the strips of the channel element and the intermediate areas not or less. This enables a guided and rapid movement in the channel element. The intermediate area between the individual strips of the channel element can also have such wetting properties that the liquid there does not wet the surface as well as in the strips of the channel element, but better than with the surface around the preconcentrate reservoir, main reservoir and channel element.

The electrodes for generating the electric field are advantageously provided directly in the region of the reservoirs in order to have the most direct possible effect on the charged particles in the liquid. Only the effect of the electric field is necessary to separate the charges. The electrodes can also z. B. have biocompatible coating to avoid direct contact of the liquid with the electrodes.

In a particularly advantageous embodiment of this embodiment, the electrodes are formed by metallic surfaces of the main reservoir and the preconcentrate reservoir, each of which may be formed by a thin, e.g. B. biocompatible layer are covered. The connecting channel element is not metallized. With such a configuration, an optimal effect of the electric field on the liquid and between the reservoirs is ensured. The pre-concentrate reservoir can be emptied with a pipette or with appropriate drainage channels.

In a particularly advantageous further development, a surface wave generating device is provided on the surface of the chip, which is aligned in such a way that it can generate a surface sound wave in the direction of the preconcentrate reservoir. Such a surface sound wave enables the movement of the liquid on the surface of the preconcentrate reservoir by the impulse transfer. In this way, the preconcentrate reservoir can be emptied. Gegebe- If necessary, additional areas with wetting properties can be provided pointing away from the preconcentrate reservoir in the direction of the surface acoustic wave path, which enable the liquid to preferentially rest thereon. In this way, the liquid can be moved along these areas with the aid of the impulse transmission of a surface sound wave. Such “conductor tracks” can possibly lead to further processing stations that are integrated, for example, on the same chip.

Of course, several such surface wave generation devices can be provided for generating movement in different directions. Filling of the main reservoir with the aid of a pulse transmission of a surface sound wave generated by a surface wave generating device can also be provided.

Preferably, the surface wave generating device is formed by an interdigital transducer, such as that used for. B. is known from surface wave filter technology. Such an interdigital transducer has intermeshing finger electrodes and can be controlled electronically in a simple manner to generate a surface acoustic wave in a piezoelectric substrate or in a piezoelectrically coated substrate. In order to obtain a laterally limited sound path, the use of a so-called "tapered" interdigital transducer, in which the finger spacing of the finger electrodes is not constant, is particularly suitable.

The channel element between the main reservoir and the preconcentrate reservoir can be a direct straight connection. If a larger volume or a longer distance is to be available for preconcentration, the channel element can also extend in a meandering manner between preconcentrate reservoir and main reservoir in all the embodiments described above.

A multiple dispenser according to the invention comprises several microdispensers according to the invention in a regular arrangement. Such a regular arrangement of several microdispensers enables e.g. B. the simple and parallel filling a micro-titer plate in which there are corresponding spots or reaction points in a corresponding regular arrangement. Fields of such points can be filled with pre-concentrated liquid at the same time using a multiple dispenser according to the invention.

If the control of the preconcentrate reservoirs for individual microdispensers can be carried out individually, then individual electrodes are provided for each individual microdispenser, which electrodes can be addressed by appropriate control devices.

In a space-saving and simple embodiment, several individual microdispensers or all microdispensers share the electrodes for applying the electrical field. Such an embodiment is easy to control and enables simultaneous processing of liquids in the individual micro-dispensers.

Multiple dispensers according to the invention can be used particularly effectively if they have an array arrangement whose dimensions correspond to the dimensions of micro-titer plates conventionally used in laboratory operation. A multiple dispenser according to the invention can thus be used directly above a micro-titer plate for filling the reaction vessels or spots located underneath.

For example, for filling microarrays with a very small grid size (eg 500 μm) or other devices with reaction spots located close to one another, the individual microdispensers of the multiple dispenser according to the invention can be designed in such a way that the respective channel elements are aligned such that they Increase the grid dimension from the preconcentrate reservoirs to the main concentrate reservoirs in the array arrangement. So even with a very small grid size of the array of the preconcentrate reservoirs and the corresponding exits, a sufficient size of the main reservoirs is possible, the one Processing of appropriate amounts of liquid allowed. The lateral distance between two reservoirs or reaction spots is referred to as the grid dimension.

In a method according to the invention for preconcentrating charged particles in small amounts of liquid, a small amount of liquid is brought onto or into a main reservoir, which is connected to a small preconcentrate reservoir via a channel element. An electric field is applied along the channel element to collect charged particles according to their polarity in the preconcentrate reservoir.

The devices according to the invention and the method according to the invention for preconcentrating DNA in a corresponding buffer solution can be used particularly advantageously.

The devices and methods according to the invention thus enable precise preconcentration, which moreover enables precise positioning of the preconcentrated material. In this way it is possible to load individual selected points and spots with liquid without it being necessary, e.g. B. flooding a whole chip for examination with liquid. Even with a limited amount of starting material, a sufficient concentration in the liquid can be obtained since only very little liquid is necessary at all.

The device according to the invention and the method according to the invention are explained in detail below on the basis of preferred configurations. The figures are schematic, not necessarily to scale. It shows

FIG. 1 shows the cross section through an embodiment of a microdispenser according to the invention, FIG. 2 shows the cross section of an embodiment of a multiple dispenser according to the invention,

FIG. 3 the bottom view of the multiple dispenser of FIG. 2,

FIG. 4 shows the cross section of a further embodiment of the multiple dispenser according to the invention with an enlargement of area A,

FIG. 5 shows the top view of a further embodiment of a microdispenser according to the invention,

FIG. 6 shows a side partial sectional view of a further embodiment of a microdispenser according to the invention, and

FIG. 7 shows a side sectional view of a further embodiment of a microdispenser according to the invention.

Figure 1 shows the cross section through a chip 1, which can be made of plastic. From the surface 21 to the surface 19, the chip is penetrated by a continuous opening, which is composed of the funnel-shaped filling opening 9 for the main reservoir 5, the capillary element 4, the preconcentrate reservoir 7 and the opening 3. The chip can be in one piece or glued together from different layers.

The connection opening between the funnel 9 and the main reservoir 5 is denoted by 17. On the underside of the chip 1 there is the metal electrode 13 over the entire surface. The second electrode 11 is located between two layers of the chip 1 at the level of the transition between the main reservoir 5 and the funnel 9. The electrodes are used to apply an electrical field E, shown symbolically by the battery 15. In the case shown, the positive pole of the battery 15 is present at the preconcentrate reservoir 7. The entirety of the microdispenser, which is shown in FIG. 1, is designated by 2. Such a microdispenser 2 is used as follows. The dispenser is loaded with about 1 to 10 μl through the funnel 9 from above. This can e.g. B. using a pipetting robot or manually. Due to the capillary action, the solution is drawn into the capillary 4 in the lower part. After applying an electrical field z. B. with the help of the battery 15, the existing volume is separated with respect to the charge of the ingredients. For example, negative particles move downward at the indicated polarity. In the special application in the treatment of DNA, z. B. negative DNA strands down and positive ions up. The components are separated according to their polarity. The negatively charged DNA preferentially collects around the lower area in the vicinity of the positive electrode and thus leads to an increased concentration. The smaller lower preconcentrate reservoir (approx. 5 to 50 nl) can then be set up by a device that is not of interest here. B. can be emptied by piezoelectric means, thermally or by air blast on a suitable substrate. Such a substrate can e.g. B. be a micro-titer plate for further investigation.

FIG. 2 shows a multiple dispenser according to the invention, which is composed of several microdispensers 2. The arrangement can contain any number of microdispensers 2, which is to be indicated by the dots in the right part of the figure. Of course, the individual microdispensers can be integrated in a single chip 1, which is formed in one piece. In the embodiment shown, the individual microdispensers 2 share the electrodes 11 and 13, which are supplied by the voltage source 15.

Figure 3 shows the corresponding embodiment from below with a view of the surface 19. The individual openings 3 of the individual microdispensers 2 are arranged in grid dimension a. The grid dimension between the individual microdispenser openings 3 advantageously corresponds to the grid dimension of a micro-titer plate to be filled or a microarray to be filled. Typical titer plates have e.g. B. 96 or 384 points. The individual microdispensers 2 of the multiple dispenser are in turn z. B. filled with a pipetting robot. Individual microdispensers can be filled with different liquids or with different DNA samples to be examined. The electrical field for the electrophoretic pre-concentration of the charged fragments can be applied in parallel to all reservoirs, since in the embodiment shown the electrodes 11 and 13 are used for all microdispensers. In an embodiment that is not shown, the electrodes of the individual microdispensers 2 can be controlled individually, so that individual control of the preconcentration in the individual microdispensers 2 is possible.

FIG. 4 shows a further embodiment of the multiple dispenser according to the invention. The course of the individual microdispensers 20 has adapted capillary elements 40. The area in which the openings 3 of the preconcentrate reservoirs 7 are located is designated by A and is shown again enlarged in the figure. With such an arrangement, in which the capillary elements 40 also overcome a lateral distance, it is possible that the openings 3 of the preconcentrate reservoirs 7 have a different grid dimension than the openings of the main reservoirs 5. Thus, the outlets 3 of the multiple dispenser arrangement can be of very small micro size Adapt titer plates, microarrays or other further processing devices without the volumes of the main reservoirs 5 being limited.

A planar configuration of the microdispenser according to the invention is shown in FIG. 5. On a solid surface 200 z. B. the surface of a crystalline solid state areas "preferred stay" are defined, which are connected to each other. In the embodiment shown, these are the areas 500, 400 and 700. The areas 500 and 700 are metallic coated surface areas, the main reservoir 500 and the Form preconcentrate reservoir 700. The area 400 is a non-metallic area which connects the areas 500 and 700. The remaining surface of the solid body 200 is silanized and thus hydrophobic, so that when using aqueous solutions the wetting properties are such that the Liquid is more preferably in the areas 400, 500 and 700 than on the remaining area of the solid surface 200. The metallic areas 500 and 700 are over corresponding Connections connected to a voltage source 15. In the embodiment shown, the positive pole of the voltage source bears against the preconcentrate region 700. The entire planar microdispenser unit of this type is designated by 22. The main reservoir can e.g. B. a diameter of 500 microns, the preconcentrate reservoir has a diameter of 100 to 200 microns and the area 400 have a width of 50 to 100 microns.

In the embodiment shown, a surface wave generating device 600 is additionally provided. In the embodiment shown, the surface wave generating device 600 consists of an interdigital transducer with interlocking finger electrodes 603, which can be contacted via flat electrodes 601. The substrate 200 is piezoelectrically (for example LiNbO ₃ ) or piezoelectrically coated in the region of the surface acoustic wave generating device. Applying an alternating electrical field with z. B. a few 10 to a few 100 MHz generates a surface acoustic wave that propagates in the direction 605 and the opposite direction. The wavelength of this surface sound wave corresponds in a known manner to the finger spacing of the electrodes 603. A surface sound wave is generated when the frequency applied essentially fulfills the resonance condition, that is to say corresponds to the quotient of the surface sound velocity of the material and the finger spacing. To generate surface acoustic waves, at least the area of the surface wave generating device 600 is piezoelectrically coated or applied to a piezoelectric substrate.

607 denotes a region which is likewise designed in its wetting properties in such a way that it is preferably wetted by the liquid. It represents a kind of "conductor track" for the liquid. Either by hand, by pipetting robot or using a microdispenser, as shown in FIG. 1, a drop of DNA solution is pipetted onto the main reservoir 500. This drop is distributed over the Entire wetting surface 500, 400, 700. If an electrical voltage is now applied between the metallic reservoir surfaces 500 and 700 designed as electrodes, this causes electrical radiation directed in the plane Field electrophoretic separation of charged particles in the liquid. If the reservoir 700 z. B. positively charged with respect to the reservoir 500, negative charge accumulates there, in particular DNA.

After a preconcentrated solution has been established in this way, an alternating electrical field can be applied to the interdigital transducer 600. The generated surface sound wave 605 transmits its impulse to the pre-concentrated solution on the pre-concentrate surface 700 and drives it out of the reservoir area. The liquid can move to other examination sites via corresponding conductor tracks 607 or can be completely emptied from the chip to another device.

FIG. 6 shows an embodiment 32 which is not integrated in a chip. 31 denotes a plastic tube, preferably made of biocompatible plastic, with a height of about 1 cm. This is followed by a metallic tip 43 which is open at the bottom and has an opening 33. The plastic tube 31 is open at the top with the opening 39. The upper region 35 corresponds to a main reservoir, while the lower region 37 represents a preconcentrate reservoir, the main and preconcentrate reservoirs being connected to one another by the channel section 34. 38 schematically designates the liquid surface during use. The metallic tip can be coated on the inside in order to avoid contact with the liquid.

41 denotes a ring-shaped metal electrode which is placed around the plastic tube 31. The lower tip 43 is metallic and can be used directly as an electrode. The electrodes are connected to the voltage source 15.

Such an embodiment can be filled from above through the opening 39 with a liquid which has components to be separated. Similarly, similar to a pipette, the liquid can be sucked through the opening 33 into the embodiment 32 of the microdispenser. Applying a voltage by means of the voltage source 15 to the electrodes 41 and 43 in the shown The polarity creates a charge separation. The positively charged particles 45 in the liquid move upwards and the negative particles 46 downwards. With the help of e.g. B. a pneumatic air blast through the opening 39, the lower region 37 of the inventive embodiment 32 of the microdispenser down z. B. emptied onto a micro-titer plate or into a reaction vessel.

FIG. 7 shows an embodiment 52 in which the channel element 54 has a smaller lateral extent than the preconcentrate reservoir 57 and the main reservoir 55. In such an embodiment, the separation of the positively charged particles 65 and the negatively charged particles 66 when a voltage is applied is shown in FIG Polarity to the voltage source 15 is further improved compared to an embodiment of FIG. 6. Just like the embodiment in FIG. 6, the embodiment in FIG. 7 can also be filled by drawing up liquid through the opening 53 into the microdispenser 52, or by filling the main reservoir 52 from above. 58 schematically denotes the liquid surface during use. Applying a pneumatic air blast to the upper opening 59 causes the preconcentrate reservoir 57 to be emptied through the opening 53, again, for. B. in a reaction vessel or to the point of a micro-titer plate.

The embodiments of Figures 6 and 7 can, for. B. with the help of an x-y actuator above a micro-titer plate to specifically fill its individual points. Both embodiments can also have funnel-shaped openings for easier filling.

The invention thus enables simple pre-concentration and emptying of the pre-concentrated liquid at defined locations. The structure is compact, simple and inexpensive and can be used or integrated in a compatible way with micro laboratories (lab-on-the-chip). Only very small amounts of sample are required. In particular when examining DNA, the hybridization times can be greatly reduced in this way, since only little liquid is required and the concentration can be correspondingly higher, even if only limited starting material is available.

Claims

claims

1. Microdispenser for generating a pre-concentration of charged particles in a small amount of liquid, with

a main reservoir (5, 35, 55, 500) for holding liquid,

a preconcentrate reservoir (7, 37, 57, 700) which is smaller than the main reservoir (5, 35, 55, 500) for receiving the preconcentrated liquid,

- A channel element (4, 34, 40, 54, 400) for connecting the main reservoir (5, 35, 55, 500) and preconcentrate reservoir (7, 37, 57, 700), and

- Means (11, 13; 41, 43; 61, 63; 500, 700) for applying an electric field via the channel element (4, 34, 40, 54, 400) from the main reservoir (5, 500) to the preconcentrate reservoir (7, 37, 57, 700).

2. Microdispenser according to claim 1, which comprises a chip (1), preferably made of crystalline material or plastic, and is integrated therein or thereon.

3. Microdispenser according to one of claims 1 or 2, which is formed in a chip (1) with two main surfaces (19, 21), the preconcentrate reservoir having a cavity (7) with a first opening (3) in the direction of a main surface (19 ) of the chip (1), the main reservoir comprises a larger second cavity (5) with a larger second opening (17) to the second main surface (21) and the channel element has a capillary (4) between the main reservoir (5) and the preconcentrate reservoir (7 ) includes.

4. Microdispenser according to claim 3, wherein the means for applying an electric field comprise electrodes (11, 13) on the side of the main reservoir (5) or the preconcentrate reservoir (7) remote from the capillary (4) and from outside the Chips (1) can be contacted.

5. Microdispenser according to one of claims 2 to 4, wherein the second opening comprises a funnel-shaped access (9).

6. Microdispenser according to one of claims 2 to 5, wherein the main reservoir (5) has a volume of 1 to 10 ul.

7. Microdispenser according to one of claims 2 to 6, wherein the preconcentrate reservoir (7) has a volume of about 5 to 50 nl.

8. A microdispenser according to claim 1 or 2, which is formed on a main surface (200) of a chip for laterally moving the amount of liquid, and in which the preconcentrate reservoir (700), the main reservoir (500) and the channel element (400) comprise surfaces , the wetting properties of which differ from the wetting properties of the surrounding main surface of the chip in such a way that a liquid is preferably present thereon, the area of the main reservoir (500) being larger than that of the preconcentrate reservoir (700).

9. A microdispenser according to claim 8, wherein the means for applying an electric field comprise electrodes in the area of the surfaces of the main reservoir (500) and the preconcentrate reservoir (700).

10. Microdispenser according to claim 9, with a biocompatible coating to prevent contact between the amount of liquid and the electrodes.

11. A microdispenser according to claim 9 or 10, wherein the main reservoir (500) and the preconcentrate reservoir (700) comprise metallized areas which form the electrodes, and the channel element (400) comprises a non-metallized area.

12. Microdispenser according to one of claims 8 to 11, wherein the channel element comprises a plurality of parallel strips between the preconcentrate reservoir and the main reservoir.

13. Microdispenser according to one of claims 8 to 12, with a surface wave generating device (600) for generating surface sound waves (605) in the direction of the preconcentrate reservoir (700) for emptying the preconcentrate reservoir (700) by pulse transmission to a liquid located there.

14. The microdispenser according to claim 13, wherein the surface wave generating device (600) comprises a preferably tapered interdigital transducer.

15. Microdispenser according to one of claims 8 to 14, in which the surfaces of the main reservoir (500), preconcentrate reservoir (700) and channel element (400) are designed in such a way that the surface (200) surrounding them is more hydrophobic than the surfaces of the main reservoir ( 500), the preconcentrate reservoir (700) and the channel element (400).

16. Microdispenser according to one of claims 1 to 15, wherein the channel element (4, 40, 400) extends in a meandering shape between the main reservoir (5, 500) and the pre-concentrate reservoir (7, 700).

17. Multiple dispenser with several microdispensers according to one of claims 1 to 16 in a regular arrangement.

18. Multiple dispenser according to claim 17, in which the microdispensers can be controlled individually via individual electrodes.

19. Multiple dispenser according to claim 17, in which a plurality of microdispensers (2, 20, 22) each share the electrodes.

20. Multiple dispenser according to one of claims 17 to 19, in which the microdispensers (2, 20, 22) are arranged in an array arrangement, preferably compatible with the dimensions of conventional micro-titer plates.

21. Multiple dispenser according to one of claims 17 to 20, in which the channel elements (40) of the microdispenser (20) are shaped such that the regular arrangement of the preconcentrate reservoir (7, 700) has a smaller grid dimension than the regular arrangement of the main reservoirs (5, 500).

22. A method for preconcentrating charged particles in small amounts of liquid, in which the small amount of liquid is brought into or onto a main reservoir (5, 35, 55, 500) via a channel element (4, 34, 40, 54, 400) a preconcentrate reservoir (7, 37, 57, 700) is connected, and an electric field is generated in a direction which is substantially parallel to the direction between the main reservoir (5, 35, 55, 500) and the preconcentrate reservoir (7, 37, 57 , 700).

23. Use of a microdispenser according to one of claims 1 to 16 or a multiple dispenser according to one of claims 17 to 21 or a method according to claim 22 for preconcentration of deoxyribonucleic acid (DNA) in a buffer liquid.