Abstract:
A method or device for integrated dosing and intermixing of small amounts of liquid, has at least one dosing reservoir ( 3 ) connected to a reaction reservoir ( 1 ) via at least one joining structure ( 11 ) and entirely filled with a first liquid. The at least one joining structure ( 11 ) is preferably dimensioned such that surface tension of the first liquid prevents the first liquid from penetrating into the reaction reservoir ( 1 ) which is entirely filled with a second liquid contacting the first liquid on the joining structure ( 11 ). A flow pattern is created in or on the reaction reservoir ( 1 ) to thoroughly mix the two liquids.

Description:
BACKGROUND OF THE INVENTION 
     The invention relates to a method for the metering and mixing of small quantities of liquid, to a device and to an apparatus for carrying out the method and to a use. 
     Diagnostic assays, in particular in the field of clinical chemistry and immunochemistry, are carried out in an automated manner to a large extent today. Defined volumes of sample liquid and reagents are pipetted into a cuvette or into the well of a microtiter plate and mixed in the corresponding automatic units. Subsequently, a first reference measurement is made in which, for example, the optical transmission through the cuvette is determined. After a certain reaction time between the sample and the reagents, a second measurement of the same parameter is made. The concentration of the sample with respect to a specific constituent or also only the presence of the constituent results by the comparison of the measured values. Typical volumes lie in sum at some hundred microliters, with necessary mixture ratios of sample to reagent being able to occur between 1:100 and 100:1. Optionally, a plurality of reagents can also be provided for mixing with a sample. In addition to the instruments just described for a high throughput, which are typically to be found in special laboratories, there are also endeavors to carry out assays in a decentral manner and without any large instrumental effort. It would be desirable in this connection if the “lab-on-a-chip” technology recently introduced could be used in which the processing of liquids on or in a chip be can carried out in an integrated manner. Assay times of less than one hour are desirable. 
     Microfluid systems are used, for example, for the movement of the liquids in which liquid is moved through electro-osmotic potentials, see for example Anne Y. Fu, et al. “A micro fabricated fluorescence-activated cell sorter”, Nature Biotechnology Vol. 17, November 1999, p. 1109 ff. 
     A method for liquid mixing in the microliter range is described in DE 103 25 307 B3 in which small liquid volumes are mixed in microtiter plates with the help of noise-induced flow. Another method for the generation of movement in small quantities of liquid on a solid surface is described in DE 101 42 789 C1. Here, a liquid is mixed or a plurality of liquids are mixed with one another with the help of surface sound waves. 
     In accordance with a method described in DE 100 55 318 A1, a quantity of liquid is placed onto a region of a substantially planar surface whose wetting properties differ from the surrounding surface such that the liquid preferably remains there, with it being held together by its surface tension. Movement of the quantity of liquid can be generated in this connection by the pulse transfer of a surface sound wave to the liquid. 
     In particular the integration of the metering and the mixing of the sample and the reagents in a cost-favorable lap-on-a-chip system is problematic. A homogeneous mixing of different quantities of liquid which are so small is difficult to realize. 
     It is necessary to define volumes of quantities of liquid precisely for the metering. This can be carried out geometrically, for example. For example, in an open system, the wetting properties of the surface can thus determine a volume, as is described in DE 100 55 318 A1. Here, the definition of the volumes takes place by hydrophilic and hydrophobic regions over the wetting angle on a substantially smooth surface. If a plurality of volumes were defined in this manner which should be brought to reaction, the volumes are moved toward one another to achieve this. On the movement on a surface, liquid residues or molecules of the analyte or of the reagent located in the liquid can remain stuck to the surface so that a volume loss or a reduction in concentration of unknown amount cannot be precluded by the movement. In addition, measures must be taken against evaporation which can in particular be problematic with longer assay times. 
     Other preparations use passages of defined cross-section which are filled with liquid in a capillary manner. If the liquid is an aqueous solution, a hydrophobic barrier which cannot be filled in a capillary manner is attached to the end of the passage. Furthermore, there is a lateral branch at this passage with a likewise hydrophobic surface which cannot be filled in a capillary manner. The cross-section and length of the passage between the hydrophobic barrier and the hydrophobic branch now determine a volume which can be separated and moved in a defined manner by pneumatic pressure through the branch (Burns et al., An integrated nanoliter DNA analysis device, Science 282, 484 (1998)). High costs arise by this type of volume definition due to the necessary wetting structuring of the surface (hydrophilic for the filling of the passage itself and hydrophobic for the barrier and the branch). In addition, it is necessary to work with air pressure, which requires corresponding devices. The passage cross-section must be small to permit the capillary filling of the measurement passage. Long passages are therefore necessary with large volumes in the range of some 100 microliters. This necessarily results in large unwanted interactions of the molecules in the liquid with the passage wall. An efficient mixing of a plurality of quantities of liquid is almost impossible in this geometry. 
     The term “liquid” in the present text includes inter alia pure liquids, mixtures, dispersions and suspensions as well as liquids in which solid particles are located, for example biological material. Liquids to be metered and to be mixed can also, for example, be two or more similar solutions which only differ by constituents dissolved therein which should be brought to reaction. 
     SUMMARY OF THE INVENTION 
     It is the object of the present invention to provide a method and a device with whose help a precise metering of quantities of liquid can be carried out simply in a large dynamic range and which permit a complete mixing of the liquids. The method should be able to be carried out in a compact lab-on-chip system. 
     This object is satisfied by a method, a device or an apparatus having the features herein. Preferred embodiments and advantageous use are also described herein. 
     In the method in accordance with the invention for the integrated metering and mixing, a metering reservoir is completely filled with a first liquid and is in communication with a reaction reservoir via at least one connection structure, with the connection structure preferably being dimensioned in relationship to the reservoir such that the surface tension of the first liquid prevents an entry into the reaction reservoir. The cross-section of the connection structure can in particular be selected to be smaller than the cross-section of the reaction reservoir for this purpose. The reaction reservoir is completely filled with a second liquid so that the second liquid comes into communication with the first liquid at the connection structure. Finally, a flow pattern is generated in the liquid in or on the reaction reservoir which results in the mixing of the liquids, with the flow pattern being maintained up to the complete homogenization of the liquids. A laminar flow pattern is preferably generated. 
     The laminar flow pattern can be generated directly in the reaction reservoir. It is equally possible for the laminar flow to be generated in at least one connection structure in the direction of the reaction reservoir and to act in the reaction reservoir in this manner. Finally, with a corresponding geometrical configuration, is also possible to excite the laminar flow in the metering reservoir such that it acts in the reaction reservoir via the connection structure. 
     In the method in accordance with the invention, the quantity of the first liquid to be metered in the metering reservoir is fixed. The first liquid is prevented from entering into the reaction reservoir. In a preferred process management, the surface tension prevents the liquid from entering into the reaction reservoir. A liquid exchange can only take place when the first liquid comes into contact with the second liquid which was brought into or onto the reaction reservoir. In this connection, a liquid exchange due to diffusion is negligible due to the smaller cross-section of the connection passage structure. An effective mixing is only effected by generation of a corresponding flow pattern in the reaction reservoir. The quantity of the second liquid is determined by the size of the reaction reservoir. 
     A metering and mixing of liquids in a large dynamic region, that is with very different mixing ratios can be carried out precisely with the method in accordance with the invention. The mixing ratio between reagents and sample liquid can be set, for example, between 1:100 up to 100:1. 
     The flow pattern can be generated by radiation of sound waves into the liquid on or in the second reservoir or in the direction of the second reservoir. 
     Surface sound waves can be used for the generation of sound waves and can be generated in a manner known per se with the help of an interdigital transducer on a piezoelectric chip which is attached to the device. The impulse transfer of the surface sound waves is used either directly or with the help of the sound waves generated with the help of the surface sound wave. The term surface sound waves in the present text also includes interface sound waves at the interfaces between two solid bodies. 
     The reservoirs and the connection structures can be configured as three-dimensional or as two-dimensional. The reservoirs and connection structures can thus be correspondingly shaped wells in a surface. In different configurations, they are correspondingly shaped hollow spaces. In a two-dimensional configuration, the reservoirs and connection structures are formed by correspondingly shaped regions of a surface which are more preferably wetted by the liquids than the surrounding regions of the surface. Surfaces which are hydrophilic in comparison with their surrounding are selected for the reservoirs and connection structures for aqueous solutions. Such wet-modulated surfaces are described, for example, in DE 100 55 318 A1. The liquids are held together as drops on the preferably wetted regions by their surface tension. 
     For simpler illustration, if it is not otherwise explicitly set forth, three-dimensional and two-dimensional realizations are each covered in the present text, even if terms are selected which only seem to describe one option. For example, the term “introduction into a reservoir” or “filling” is thus also used for the application of a liquid to a two-dimensional reservoir area. In a similar manner, the term “movement through the connection structure” is, for example, also used, etc., for the movement of liquid on a two-dimensional connection structure. The “volume” or the size of a “cross-section” in an analog manner means the surface or the width, for example, in two-dimensional realizations. 
     The connection structure can be a correspondingly dimensioned opening between the metering reservoir and the reaction reservoir. A particularly precise process management utilizes the capillary force in a connection capillary structure which is wetted by the first liquid and is filled by the capillary forces from the metering reservoir. The capillary forces decrease abruptly at the inlet point of the connection capillary structure into the reaction reservoir due to the enlarged cross-section so that a discharge of the first liquid from the connection capillary structure into the reaction reservoir is prevented. Only when the second liquid is introduced into the reaction reservoir or is applied onto the reaction surface does the second liquid come into communication with the first liquid so that a mixing can occur. 
     With a three-dimensional metering device, the reservoirs are filled in an aspect of the metering method through filling openings which are preferably located in the upper termination of the reservoir. 
     The metering reservoir can be formed by a correspondingly dimensioned volume. In a particularly preferred aspect of the method in accordance with the invention, a reservoir capillary structure is used as the metering reservoir and has at least two openings along its extent. The capillary structure can be filled through an opening. Liquid enters through the first opening and moves up to the second opening driven by the capillary force. The reservoir capillary structure is selected as the capillary structure such that the liquid front of the moving liquid takes up the whole cross-section of the capillary structure. No further openings in the system are open except for the filling opening and the second opening. The liquid stops its movement at the second opening. Since no further venting openings are provided, a counter pressure builds up at the other side of the second opening which prevents a further liquid movement. In addition, the capillary force reduces abruptly at the second opening. A further filling beyond the second opening is therefore not possible up to a specific threshold of the filling pressure. In this manner, a precise volume is defined in the reservoir capillary structure due to the path between the two openings in order to permit a precise metering. In a modification, two second openings arranged symmetrical to the filling opening are used. The liquid volume of the liquid metered in such a reservoir capillary structure then corresponds to the spacing of these two second openings. 
     A further development uses a reservoir capillary structure having a plurality of such selectable openings which are opened in dependence on the desired metering volume of the first liquid. If openings are opened which are further away from the opening used as the filling opening, the liquid can enter up to these openings and take up a larger volume. 
     The metering reservoir in this process management corresponds to the volume of the reservoir capillary structure filled with first liquid. The remaining part of the reservoir capillary structure is part of the reaction reservoir. 
     Open filling structures which are connected to the metering reservoir or to the reaction reservoir via feeds can be used for the filling of the metering reservoir. The respective liquid can be introduced manually or automatically into the respective filling structure with the help of a pipette, for example. The liquid moves into the respective reservoir through the respective feed. In configurations in which the reservoirs are provided as wells or hollow spaces in a solid body, the filling structures are also selected correspondingly. The feeds can then be correspondingly dimensioned passages, for example. 
     In a further development, the feed or feeds are selected as a capillary structure. The liquid to be introduced then automatically moves out of the filling structure into the respective reservoir due to the capillary forces. 
     Another advantageous aspect of the method in accordance with the invention uses a plurality of preferably differently sized metering reservoirs which are in communication with the reaction reservoir via connection structures. In addition, the metering reservoirs are in communication with a filling opening. The connection structures between the individual metering reservoirs and the reaction reservoir can first be closed in one configuration and be opened for the selection of the desired metering reservoir. In another aspect, the desired metering reservoir with the desired volume is selected in that the remaining connection structures to the other metering reservoirs are closed. 
     In a modification of this process management, first all the metering reservoirs are filled and then the connection structure of the desired metering reservoir is opened. In this connection, individual metering reservoirs are optionally filled through other metering reservoirs. Such a process management also makes possible the filling of a larger number of metering reservoirs through only one filling opening and thus only one position of a filling device, e.g. of a pipette tip. This process management has the advantage that the corresponding filling device does not have to be moved and so the device effort is low. Only after the complete opening of all metering reservoirs is the selected metering reservoir connected to the reaction reservoir by opening the corresponding connection structure. 
     Both the opening and the closing can be effected by a melting process on a suitable selection of the material of the metering device used. A plastic part is, for example, suitable as a metering device. The connection structures are either first closed, with the desired connection structures being melted open prior to use to establish a connection. In another process management, metering device are used in which the connection structures are first open and the connection structures not required are closed by a melting process prior to use. 
     In another process management, specifically for a two-dimensional configuration, the connection between the two liquids is established via a small “bridging drop” which is brought between the two liquids and generates a liquid bridge. The bridging drop has a smaller volume than both the first quantity of liquid and the second quantity of liquid. 
     A configuration is particularly advantageous in which more than one connection structure is present between a metering reservoir and the reaction reservoir. The liquid exchange can take place here—driven by sound waves, for example—in a circuit until a complete homogenization of the liquids has occurred. 
     The method in accordance with the invention is not limited to the metering of one quantity of liquid to a second quantity of liquid. A plurality of quantities of liquid can be provided simultaneously or successively to the metering to the liquid in the reaction reservoir with a corresponding number of metering reservoirs and connection structures which connect these metering reservoirs to the reaction reservoir. 
     A device in accordance with the invention with which the method in accordance with the invention can be carried out has at least one metering reservoir for a first quantity of liquid. Furthermore, a reaction reservoir for a second quantity of liquid and at least one connection structure between the two reservoirs are provided. The connection structure is preferably dimensioned in relationship with the reservoir such that the first liquid cannot enter into the reaction reservoir due to its surface tension. Finally, the device in accordance with the invention has a device for the generation of preferably one laminar flow pattern for the mixing of liquid in the reaction reservoir. 
     A preferred embodiment has at least one sound wave generation device for the radiation of sound waves into the reaction reservoir or in the direction of the reaction reservoir for the generation of the flow pattern. The at least one sound wave generation device is preferably formed by a surface sound wave generation device, in particular by an interdigital transducer on a piezoelectric chip. 
     The reservoirs and the at least one connection structure can be configured as wells or as hollow spaces in a solid body. In a two-dimensional configuration of the device in accordance with the invention, the reservoirs and connection structures are formed by correspondingly shaped regions of a surface which are more preferably wetted by the liquids than the surrounding regions of the surface. Such wet-modulated surfaces are described, for example, in DE 100 55 318 A1. 
     A three-dimensional embodiment of the metering device in accordance with the invention can, for example, include wells in a solid body which are closed by a cover to form the reservoirs or connection structure. The cover can be made in a simple manner from a foil, preferably of plastic. 
     An apparatus in accordance with the invention with which the method in accordance with the invention can be carried out while using a device in accordance with the invention includes a receiver for a device in accordance with the invention. When the device is inserted, the at least one device for the generation of a flow pattern is electrically contacted. The apparatus in accordance with the invention furthermore has controllable filling devices. e.g. pipettes or dispensers, which are arranged above the filling structures when the device is introduced into the receiver. The precision demands on the filling devices are not very high when using a device in accordance with the invention or when carrying out the method in accordance with the invention since the metering only takes place inside the device itself. Finally, the apparatus has a control for the control of the time procedure of a protocol which takes over the control of the device for the generation of the flow pattern and of the filling devices. Preferred embodiments include opening devices for the opening of individual filling structures, venting openings or barrier structures or devices for the closing of individual barrier structures. 
     The device in accordance with the invention can also satisfy other functions with a corresponding equipping, e.g. if a heating device is provided for the temperature control. Finally, the e.g. electrical or optical evaluation an also be integrated as well. 
     The method in accordance with the invention can be carried out simply and in an automated manner using an apparatus in accordance with the invention. Disposable parts can be used without problem as devices in accordance with the invention for the integrated metering and mixing. 
     Advantages of the device in accordance with the invention, of the apparatus in accordance with the invention and preferred embodiments of the dependent claims result from the above description of the advantages and preferred configurations of the method in accordance with the invention. 
     The method in accordance with the invention, the device in accordance with the invention and the apparatus in accordance with the invention can be used particularly effectively for the metering and mixing of biological liquids in which a precise metering of very small quantities of liquid is required. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments and aspects of the invention will be explained in detail with reference to the enclosed Figures. The Figures are not necessarily to scale and serve for schematic presentation. There are shown: 
         FIG. 1  a plan view of a metering device in accordance with the invention in an open state; 
         FIG. 2  a cross-section in the direction of view II through the embodiment of  FIG. 1 ; 
         FIG. 3  a plan view of a further embodiment of a metering device in accordance with the invention; 
         FIG. 4  a plan view of a third embodiment of the metering device in accordance with the invention, 
         FIG. 5  a plan view of a fourth embodiment of the metering device in accordance with the invention; and 
         FIGS. 6   a - 6   f  different stages in the carrying out of a method in accordance with the invention having this embodiment. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIG. 1  shows a plastic part with chambers  1 ,  3 . The plastic part  5  can, for example, be manufactured in an injection molding process. The cover of the chamber is effected by a thin plastic foil  2  which is laminated on and which is visible in  FIG. 2  and is not shown in  FIG. 1  to illustrate the inner workings of the plastic part  5 . The connection between the chambers  1  and  3  takes place via two restrictions  11 . Reference numeral  13  designates the wall between the chambers  1  and  3 . 
     In  FIG. 1 , the positions of the filling openings  7  and  9  are indicated which are provided in the plastic foil  2  which is, however, not shown in  FIG. 1 . 
     An acoustic chip  15  is located beneath the chamber  1 , which also called a reaction chamber in the following, said chip for example being able to be a piezoelectric solid body chip on which an interdigital transducer is applied in a manner known per se for the generation of surface sound waves. The interdigital transducer is configured such that the surface sound waves generated with it permit a sound wave radiation into the reaction chamber  1 . The radiation of sound waves into a liquid volume which is separated from the interdigital transducer generating surface sound waves by a solid body is described in DE 103 25 307 B3. In an analog manner, the acoustic chip  15  can also be provided on the foil  2  or in a side region. 
     The acoustic chip  15  is connected via electrical connections, not shown, to an alternating voltage source with which an alternating voltage of a frequency of some 10 MHz can be generated in order to generate surface sound waves with the interdigital transducer which result in the radiation of sound waves into the reaction chamber  1 . 
     The position of the acoustic chip  15  is indicated in  FIG. 1 , although the chip would not be visible per se in this view since it is attached to the lower side of the device in the embodiment shown. In the sketch of  FIG. 1 , the acoustic chip is drawn in the form of parallel lines which should only schematically indicate the alignment of the individual finger electrodes of the interdigital transducer on the piezoelectric chip  15 . The radiation direction of the surface sound waves of an interdigital transducer aligned in this manner is perpendicular to the alignment of the finger electrodes. 
     The required size of the chamber  1  serving as the reaction reservoir depends on the frequency of the sound waves used. In this connection, the smallest extent should be very much larger than the wavelength of the sound used. Finally, the extent of the reaction chamber  1  in the propagation direction of the sound waves should be approximately one order of magnitude larger than the extent of the restrictions  11 . The smallest extent of the reservoir amounts, for example to 1 mm to 10 mm at a sound wavelength of, for example, 100 μm. The total length of the passage system amounts to some centimeters. The filling openings  7 ,  9  are at least one order of magnitude smaller than the reaction chamber  1 . 
     The device in accordance with the invention of this embodiment is used as follows. The reaction reservoir comprises, for example, 100 μl or 150 μl whereas the metering reservoir comprises 5 μl. Such liquid volumes are in particular characteristic for a number of diagnostic applications. First, the metering reservoir  3  is filled with a first liquid through the filling hole  7 , which can take place through capillary force, for example. The liquid will stop at the restrictions  11  since here the capillary force becomes abruptly smaller due to the large diameter of the reservoir  1 . Subsequently, the reservoir  1  is filled with a second liquid through the filling holes  9 . A possible overspill of liquid on the respective filling holes  7 ,  9  is not critical. The liquid of this overspill does not participate in the following mixing process for geometrical reasons, in particular when the following mixing process is effected by a laminar flow pattern. In this manner, the volumes of the two liquids are now geometrically defined without any great precision of the filling devices used, pipettes for example, being necessary. The liquids are in contact at the restrictions  11 . Diffusion only takes place to a negligible extent due to the narrow cross-section of the restrictions  11 . A homogenous mixing of the total quantities of liquid is achieved with the help of the acoustic chip  15 . Acoustic energy is radiated into the defined volumes of the liquids by application of an alternating voltage to an acoustic chip and a lamina flow pattern is generated. The liquids or their constituents are mixed and optionally brought to reaction. The result of this reaction can be read off optically or electrically, for example. It is of advantage in this connection that the filling holes  7 ,  9  do not have to be closed. 
     The metering and mixing of the liquids therefore takes place in a cost-favorable device  5  optionally configured as a disposable cartridge. The metering is additionally very simple. Even if an overspill of the filling holes occurs, it will not participate in the mixing reaction for geometrical reasons and/or due to the laminar flow pattern used. 
       FIG. 3  shows another embodiment of a metering device in accordance with the invention. What is shown here is the portion of a plastic body  105  which contains the metering device which likewise includes the wells in the plastic structure  105 . The reaction reservoir  101  with filling holes  109  is visible.  103  shows a capillary structure having a plurality of openings, with the opening  107  serving as the filling opening. The capillary structure  103  represents a metering capillary structure which is in communication with the reaction reservoir  101  via connection capillary structures  111 . The total structure is likewise closed by a plastic foil. The openings  107 ,  109 ,  121  and  122  not visible per se in the open representation are also indicated in this embodiment to show their relative position. The acoustic chip  115  with an interdigital transducer is likewise indicated in its position arranged beneath the device and accordingly not actually visible in the illustration. The acoustic chip  115  corresponds to the chip  15  described with reference to  FIGS. 1 and 2 . 
     Different mixing ratios can be set using such a metering device. The filling takes place via the filling hole  107  which is open. All other holes  109 ,  121 ,  122  are first closed. The volume of the first liquid filled in can now be set by selective opening of the holes  121 ,  122 . If e.g. only one hole  121  in direct proximity to the filling opening  107  and the hole  121  arranged symmetrically thereto on the other side are open, a liquid volume can be defined of a length which corresponds to the spacing between the two open openings  121 . 
     The capillary structure  103  in this connection has the effect that the front of the liquid fills up the total cross-section of the capillary structure  103 . If no further venting holes are open, a counter-pressure is built up which results in the stopping of the liquid. A movement beyond the opened holes  121  is therefore not possible. This effect is amplified in that the capillary force effecting the movement becomes smaller through the open opening  121 . 
     If the two outer openings  122  are opened, a correspondingly larger volume results. 
     In both cases, the residual volume in the passage  103  and the connection capillary structures  111  can be filled via the reaction reservoir  101  through the openings  109  then to be opened. The residual volume of the passage  103  then counts toward the reaction reservoir. 
     The characteristic dimensions of an embodiment in accordance with  FIG. 3  correspond to the characteristic dimensions of  FIGS. 1 and 2 . 
     With such an embodiment, the setting of different mixing ratios is therefore possible in a simple manner. Depending on how much of the first liquid should be metered to the second liquid, the corresponding openings  121 ,  122  are opened. This can take place, for example, by a simple piercing of the plastic foil at correspondingly marked positions. The further function substantially corresponds to the embodiment of  FIGS. 1 and 2 . 
       FIG. 4  shows another embodiment. A plurality of metering reservoirs  203 ,  223  are provided here which are in communication with the reaction reservoir  201  via connection capillary structures  211 ,  212 . The metering reservoirs  203 ,  223  have differently sized volumes and are in communication via a connection passage structure  216 . The filling opening  207  is located in the connection passage structure  216 . The metering reservoirs  203 ,  223  have venting openings  221 . The connection passage  216  in the embodiment shown is likewise connected to the reaction reservoir  201  via a connection capillary structure  210 . The structure  210  also comprises a venting hole  221 . Finally, filling openings  209  are provided in the reaction reservoir  201 . 
       217 ,  218 ,  219 ,  220  and  224  schematically represent barrier structures. The total metering device of  FIG. 4  is provided in a plastic part which is terminated by a film having openings  207 ,  209 ,  221 . The metering device of  FIG. 4  can likewise be a disposable part which is prefabricated ex works. In this connection, the barrier structures  217 ,  218 ,  219 ,  220 ,  224  are first made closed in the embodiment shown. 
     The filling openings  207 ,  209  and the venting openings  221  which are not visible per se in the open position are also indicated in their position in the illustration of  FIG. 4 . In addition, an acoustic chip  215 , which corresponds to the already described acoustic chip  15 ,  115  is located beneath the arrangement of  FIG. 4 . The acoustic chip  215  is also indicated in  FIG. 4 , although it is not visible per se in this illustration since it is located beneath the arrangement. 
     The characteristic dimensions in the embodiment of  FIG. 4  also correspond to the characteristic dimensions of the embodiment of  FIGS. 1 and 2 . 
     A decision is first made for the use of the embodiment in a process management as to which of the metering reservoirs  203 ,  223  should be filled with liquid to define a corresponding volume of liquid. The metering reservoir  223  is selected for explanation in the present description. After the selection has been made, the corresponding barriers  217 ,  219  adjoining the metering reservoir  223  are melted open, for example by a heater or using laser energy. This can, for example, take place with the help of an automatic machine which processes the metering device. 
     The correspondingly selected metering reservoir  223  can then be filled via the filling opening  207  and be used for the metering. In this connection, the metering is carried out in a similar manner, for example, as described in the embodiment of  FIGS. 1 and 2 . The dimensions of the structures are in particular selected such that a filling of the metering reservoir can take place through the effect of the capillary force. Alternatively, a filling can take place with pressure. The deaeration opening  221  is arranged such that a complete filling of the reservoir is possible. 
     The liquid does not enter into the reaction reservoir  201  due to the capillary effect which becomes abruptly smaller at the inlet position of the connection capillary structure  211  into the reaction reservoir  201 . Only on the filling of the reaction reservoir  201  through the filling openings  209  does liquid from the reaction reservoir  201  come into communication with liquid in the connection capillary structure  211 . The further function substantially corresponds to the embodiment of  FIGS. 1 and 2 . 
     If the reservoir  203  is selected, the procedure is analogous while using the corresponding barrier structures  218 ,  220  and the connection capillary structure  212 . 
     Another aspect of this embodiment does not comprise any barrier structures  217 ,  219  ex works. A decision is in turn first made before use as to which of the metering reservoirs  203 ,  223  should be used. If e.g. metering reservoir  223  is selected, the other metering reservoir  203  is decoupled with the help of an automatic machine which melts the corresponding connection passage structures closed by application of heating energy or laser energy at the positions of the barriers  218 ,  220  which are adjacent to the meter reservoir  203  not to be used. 
     The individual metering reservoirs  203 ,  223  can also each be connected to the reaction reservoir  201  via a plurality of connection capillary structures  211 ,  212 , which are open on the selection of the corresponding metering reservoir, in the embodiments in accordance with  FIG. 4 . 
     In addition to the connection structures  211 ,  212  with the barrier structures  219 ,  220 , a further connection capillary structure  210  can be provided which connects the connection passage  216  to the reaction reservoir  201 . This connection capillary structure  210  also includes a venting opening  221  and, optionally, a barrier structure  224 . The additional passage  210  can serve for the forming of a circuit which promotes an effective mixing. After one of the metering reservoirs  203 ,  223  has been selected, it is filled. Let this again be the metering reservoir  223  for the purpose of the description. An embodiment is first described in which the barrier structures  217 ,  218 ,  219 ,  220 ,  224  are first closed. The barrier structure  217  is melted open as described for the filling of the reservoir  223 . Liquid which fills the metering reservoir  223  and the connection capillary structure  211  is introduced through the filling opening  207 . The connection capillary structure  210  is also filled with this liquid. The filling takes place through capillary force, for example. 
     The barrier structures  219 ,  224  can now be melted open. The liquid does not enter into the reservoir  201  due to the capillary effect which becomes abruptly lower at the inlet positions of the connection capillary structures  211 ,  210 . The filling of the reservoir  201  with a second liquid through the openings  209  effects the contact of the liquids at the inlet positions of the connection capillary structures  210 ,  211 . The generation of a laminar flow, for example, with the acoustic chip  215  then effects an effective mixing of the liquids. A circuit movement of the liquids can occur in this connection. 
     With such an embodiment utilizing capillary forces in the connection capillary structures  210 ,  211 ,  212 , the barrier structures  224  can also be completely dispensed with. Particularly with an embodiment having only two metering reservoirs, as is shown in  FIG. 4 , the connection capillary structure  210  in every case participates in the circuit process so that a decoupling is not necessary. 
     In another process management, the barrier structures  219 ,  224  are only melted open after introduction of the second liquid into the reservoir  201 . The process management is otherwise the same. With such a process management, the connection structures  210 ,  211 ,  212  do not necessarily have to exert capillary action on the liquids. 
     Another process management using a device in accordance with  FIG. 4  uses barrier structures  217 ,  218 ,  219 ,  220 ,  224  which are originally open. First liquid is introduced through the filling opening  207 . It flows due to capillary effect into the metering reservoirs  203 ,  223  and into the connection capillary structures  210 ,  211 ,  212 . They do not enter into the reaction reservoir  201  since the capillary effect breaks down at the inlet positions of the connection structures  210 ,  211 ,  212  into the reaction reservoir  201 . Only now is a decision made as to which metering reservoir, and thus which metering volume of the first liquid, should be used. Let this again be the metering reservoir  223  for the purpose of the present description. The barrier structures  218 ,  220  are then melted closed as described and the metering reservoir  203  not used with the liquid located therein is thus decoupled. Then the second liquid is filled into the reaction reservoir  201 . The process management following thereon corresponds to the already described circuit process management. 
       FIG. 5  shows the schematic plan view of a further embodiment of a metering device in accordance with the invention. The total arrangement  50  is arranged at the surface of a plastic carrier  305 . The reaction reservoir  1  is formed, for example, by a milled well of a depth of 1 mm and has a volume of, for example, 20 μl. In the example shown, two metering reservoirs  303  adjoin this and are formed, for example, by wells milled with a depth of 1 mm and each having a volume of 10 μl. The metering reservoirs adjoin the reaction reservoir  301  via two respective restrictions  311 . Filling structures  307  and  309  are connected to the metering reservoirs  303  or to the reaction reservoir  301  respectively via feeds  308  and  310  respectively. The filling structures  307 ,  309  are likewise formed, for example, by 1 mm deep wells in the plastic carrier  305 . The feeds  308 ,  310  are wells with a depth of 300 μm in the example shown. A plastic foil, not visible, similar to the plastic foil  2 , as can be recognized in  FIG. 2 , is located over the total arrangement. In the region of the filling structures  307 ,  309  to be used, this plastic foil is pierced as required, for example, to be able to introduce liquid with the help of a pipette. 
       315  designates, in a schematic representation, an interdigital transducer which is formed from a large number of mutually engaging finger electrodes. The function was already explained above with respect to the other embodiment. When an electric alternating field is applied to the interdigital transducer, a pulse can be transmitted in the direction of the arrow drawn to the liquid in the limb  304  of the metering reservoir  303  shown in the upper half of the Figure. 
       FIGS. 6   a  to  6   f  show a sequence in the carrying out of a method in accordance with the invention with the embodiment of  FIG. 5 . Lines  320  and  322  were drawn to indicate the arrangement of the reaction reservoir  301  with the feeds  310  and the filling structures  309  which would otherwise not be recognizable in the illustrations of  FIGS. 6   a  to  6   f  due to the contrast being too low. 
     In the Figures, in each case only a portion is shown in which one of the metering reservoirs  303  is completely visible. 
       FIG. 6   a  shows a state in which a liquid, with a dark color here, is filled into the metering reservoir  303  through the filling structure  307  and the feed  308 . For this purpose, the covering plastic foil was pierced in the region of the filling structure  307  and the liquid was introduced into the filling structure using a pipette. It can be clearly recognized that the liquid with a dark color does not enter into the still empty reaction reservoir  301  due to its surface tension at the restrictions  311 . The volume is precisely defined in the metering reservoir  303  between the restrictions  311  and the feed  308  (in the example shown 10 μl). 
     A liquid with a light color was thereupon introduced into the reaction reservoir  301 .  FIG. 6   a  shows the start of this filling process. For this purpose, the covering plastic foil was pierced in the region of the right hand filling structure  309  and it was started to fill in liquid with the help of a pipette. This liquid flows through the feed  310  into the reaction reservoir. It can be recognized in  FIG. 6   a  that this process is currently on-going. The liquid border is located approximately at the dotted auxiliary line  324  in this snap-shot. 
       FIG. 6   b  shows a state in which the whole reaction reservoir  301  is filled with the light liquid. A liquid exchange with the dark liquid in the metering reservoir  303  has only taken place to a very limited degree at this point in time. 
     The application of an electrical alternating field to the interdigital transducer  315  effects a pulse transfer to the liquid in the left hand limb  304  of the metering reservoir  303 .  FIG. 6   c  shows how the laminar flow thereby generated in the metering reservoir  303  has the effect that the dark liquid enters into the reaction reservoir  301 .  FIGS. 6   d  and  6   e  show the continuation of this process. It can clearly be recognized how the dark liquid, which was originally located in the metering reservoir  303 , and the light liquid, which was located in the reaction reservoir  301 , mix. 
       FIG. 6   f  shows the state at the end of the process. The liquids in the metering reservoir  303  and in the reaction reservoir  301  are mixed homogeneously, which can be recognized by the homogeneous shading. A further exchange with the liquid in the feeds  310  from the filling structures  309  to the reaction reservoir  301  has not taken place. The quantity of the supplied light liquid is therefore exactly determined by the dimensions of the reaction reservoir  301 . Since the dimensions of the metering reservoir  301  precisely fix the quantity of the metered dark liquid, a very precise metering process has thus been carried out so that the quantities of the different liquids in the mixture present in  FIG. 6   f  are precisely determined. 
     The embodiment shown in  FIGS. 5 and 6  has two metering reservoirs  303 . Other embodiments only have one metering reservoir or even more metering reservoirs in order to be able to meter different quantities. The two metering reservoirs  303  shown are of equal size in this embodiment. To be able to meter different quantities, differently sized metering reservoirs can also be used. 
     Barrier structures such as were described with reference to  FIG. 4  can also be provided with an embodiment of  FIGS. 5 and 6 . In this manner, the number of connected metering reservoirs can also be monitored, as is also described for the embodiment of  FIG. 4 . 
     In  FIG. 5 , only an interdigital transducer  315  is shown by way of example. However, even more interdigital transducers can be provided on the plastic carrier  305  to be able to address different metering reservoirs at different points in time and to be able to generate laminar flow in the individual metering reservoirs to effect a mixing with a liquid in the reaction reservoir. 
       FIGS. 6   a  to  6   f  show that the method in accordance with the invention in particular also results in a laminar flow mixing the liquids without a pressure build-up. 
     A device in accordance with the invention can also include more than two metering reservoirs with corresponding connection structures. A plurality of metering reservoirs can then be connected “in series” in the circuit to enlarge the metering volume of the first liquid. With such an embodiment, the individual metering reservoirs can have different or equal sizes. 
     Specifically with a process management in which a circuit of the liquids is used, a reaction between the liquids does not only take place in the part of the device designated by reservoir reaction. For delineation with respect to the use of the term “metering reservoir” with which the metering of the first liquid is carried out, the term “reaction reservoir” was nevertheless used in the present text since, in particular with the embodiment shown, the reaction reservoir is the main structure in which the reaction takes place due to its size. It is, however, also possible in particular with the embodiments in accordance with  FIG. 1 ,  FIG. 4  or  FIG. 5 , for example, that the metering reservoirs and the reaction reservoir are e.g. of equal size and a reaction also takes place in both reservoirs with a circuit process management. 
     The metering and mixing device in accordance with the invention can be processed in an automatic machine which fills the liquids into the device, temperature controls the device, controls the chips and also opens filling holes or closes or opens barriers. In addition, the electrical or optical evaluation can e.g. optionally also be carried out using such an automatic machine. Such automatic machines can sensibly be used in diagnostics or generally in the automation of the laboratory. 
     It can therefore be advantageous, for example, if, in the embodiments in accordance with  FIG. 3 ,  4  or  5 , the filling of the reservoirs only takes place through one or at most two filling structures since this simplifies the adding of the liquid through the automatic machine. Corresponding pipetting heads or dispensers for filling can then be configured as stationary. 
     Total volumes of up to 1 ml with individual volumes of e.g. only 100 nl can be processed, for example, with the embodiments shown. 
     A metering and mixing of liquids in a large dynamic region, that is with very different mixing ratios, can be carried out precisely with the method in accordance with the invention. The demands on the precision of the filling devices used are not high since the metering takes place by the process management in accordance with the invention or by the use of the device in accordance with the invention. The mixing ratio between reagents and sample liquid can be set, for example, between 1:100 up to 100:1. 
     REFERENCE NUMERAL LIST 
     
         
           1  reaction reservoir, reaction chamber 
           2  plastic foil 
           3  metering reservoir, metering chamber 
           5  plastic part 
           7 ,  9  filling openings 
           10  device for the integrated metering and mixing 
           11  restrictions 
           13  boundary wall 
           15  acoustic chip 
           20 ,  30 ,  50  device for the integrated metering and mixing 
           101  reaction reservoir, reaction chamber 
           103  metering capillary structure 
           105  plastic part 
           107 ,  109  filling openings 
           111  connection capillary structure 
           115  acoustic chip 
           121 ,  122  openings 
           201  reaction reservoir, reaction chamber 
           203  metering reservoir, metering chamber 
           207 ,  209  filling openings 
           210 ,  211 ,  212  connection capillary structures 
           215  acoustic chip 
           216  connection passage structure 
           217 ,  218 ,  219 ,  220  barrier structures 
           221 ,  222  venting openings 
           223  metering reservoir, metering chamber 
           224  barrier structure 
           301  reaction reservoir, reaction chamber 
           303  metering reservoir, metering chamber 
           304  part of a metering reservoir 
           305  plastic part 
           307 ,  309  filling structures 
           308 ,  310  feeds 
           311  restrictions 
           315  interdigital transducer 
           320 ,  322  auxiliary lines 
           324  liquid boundary