Abstract:
A device for carrying out chemical and/or biological reactions comprises a sample chamber ( 38 ) formed by a first portion ( 12 ) and a second portion ( 26 ) and designed for holding the sample. With the aid of a moving means ( 46,50 ) the sample can be moved in the sample chamber ( 38 ). The second portion ( 26 ) is connected via an intermediate element ( 27 ) with a heating and cooling-control element ( 29 ) for heating and cooling the sample. For ensuring good temperature conductivity and resistance to the sample of the second portion ( 26 ), in a preferred embodiment, the second portion ( 26 ) is made of ceramic.

Description:
BACKGROUND 
       [0001]    1. Field of the Disclosure 
         [0002]    The disclosure relates to a device for carrying out chemical and/or biological reactions. 
         [0003]    2. Discussion of the Background Art 
         [0004]    With such devices tissue sections, cells, cell organelles, cell constituents, genomic or plasmid DNA, cDNA, RNA, e.g. mRNA, siRNA, microRNA as well as DNA or RNA analogs, such as PNA, LNA, proteins, in particular antibodies, peptides, polysaccharides, saccharides, metabolites as well as educts and products of chemical or physiological reactions and other molecules are examined. In this connection, the molecules, cell constituents, organelles, cells or tissues to be analyzed are placed either directly or indirectly via linking molecules or gel carriers onto the surface of an object carrier, normally a glass object carrier, and mounted there via covalent, coordinate or hydrogen bridge bonds to the surface. Placing of molecules can also be obtained by synthesizing on the surface, in particular of polymers, and previous mounting of one or a plurality of synthetic elements, or by mounting after synthesizing. Alternatively, molecules, cell constituents, organelles, cells or tissues can be placed onto the carrier surface and mounted there, the former interacting with the molecules, cell constituents, organelles or cells to be analyzed by covalent, coordinate, hydrogen bridge bonds, dipole-dipole-interactions or by van der Waals forces. 
         [0005]    Detection of the molecules, cell constituents, organelles, cells or tissues to be analyzed can be effected by a reaction with a color or by bonding of a color. Detection can also be effected by chemical or enzymatic reactions, such as oxidation of silver ions e.g. by thiol groups, conversion of a substrate into a color, chemiluminescence or a polymerase chain reaction. Further, indirect detection via specifically binding molecules, such as antibodies, biotin and streptavidin, complementary DNA or RNA which, on their part, can be detected e.g. by applying the aforementioned methods, is also possible. Further, detection with the aid of physical method, such as detection of the radioactive decay of radioisotope-marked molecules, conductivity, light refraction, light absorption or changed surface properties is possible. Also, bound molecules, cell constituents, organelles, cells or tissues can be analyzed on the surface or in a condition as removed from the surface with the aid of different analyzing techniques, such as fluorescence-activated cell sorting (FACS), electrophoresis, mass spectroscopy, elementary analysis, NMR spectroscopy or IR spectroscopy. 
         [0006]    The methods described can be applied for the purpose of examination including detection, quantification and characterization of molecules, cell constituents, organelles or cells. For example, the presence, quantity or properties of various molecules, such as synthetic products, saccharides or polysaccharides, metabolites, active substances of medicines, peptide or protein quantities, changes to or of peptides or proteins, post-translational modifications of proteins, e.g. phosphorylation and/or dephosphorylation, methylation and/or demethylation, glycosylation and/or deglycosylation, the specificity and affinity of antibodies, genomic changes, such as loss or multiplication of alleles, chromosomes or chromosome segments, changed gene sequences or other sequences, alternative splice variants of genes, changes of gene activities, changes or modifications of cell surfaces, or the presence, quantity or type of bacteria, viruses, fungi or other pathogens as well as the correspondingly formed antibodies, can be analyzed and detected. 
         [0007]    Such examination of chemical and/or biological samples can serve, for example, for characterization of reactions or molecules, research of metabolic processes, regulatory mechanisms, or characterization or diagnosis of diseases and/or check of therapies. 
         [0008]    The device described hereunder serves for improving the interaction of the subject molecules, cell constituents, organelles, cells or tissues with the molecules, cell constituents, organelles or cells in solution, as well as the reactions by optimized distribution and more uniform temperature control. 
         [0009]    Hereunder the examination of the gene expression with the aid of DNA microarrays is exemplified. 
         [0010]    For this purpose, for example, DNA is placed onto the surface of an object carrier. Placing of the DNA may occur in all ways known in the art including dripping with the aid of a robot. Thus, the position of the individual DNA pieces on the object carrier is known. The DNA pieces combine with the surface of the object carrier and adhere thereto such that their positions do not change in the subsequent analyzing process. 
         [0011]    In the next step, RNA is taken, for example, from a tumor to be analyzed. With the aid of enzymes, the RNA is transformed into DNA and subsequently marked with suitable markers, particularly fluorescent color markers. 
         [0012]    Additionally, a comparative sample with healthy tissue is produced. The healthy DNA is also marked with a suitable marker. Preferably, the marker is a fluorescent marker of another color such that the healthy tissue is marked with a greenly fluorescent marker and the tissue to be analyzed taken from the tumor, for example, with a red color marker. 
         [0013]    Subsequently, both samples are placed onto the entire object carrier. The DNA strands included in the two samples bond via hydrogen bridge bonds (base pairing) with the complementary DNA strands (hybridization) on the surface of the object carrier. Bonding of the DNA included in the samples with the DNA pieces adhering to the object carrier is effected in a hybridization process. Subsequently, the object carrier is washed such that only firmly adhering DNA pieces and hybridized DNA from the two samples are present on the object carrier. 
         [0014]    After the object carrier has been dried, it is subjected to a detecting process. In this process, the individual positions of the object carrier to which DNA pieces adhere are analyzed using a suitable microscope. In doing so, the fluorescent markers coupled to the DNA are stimulated by laser light, for example, such that the fluorescent markers fluoresce in the corresponding color. If a certain position to which a DNA piece adheres appears as a red spot, for example, it can be concluded that this gene was active in the tumor tissue but not in the healthy tissue. If a spot fluoresces greenly, it can be concluded that this gene was only active in the healthy tissue. When a yellow fluorescence occurs, the corresponding gene was active in both tissues. With the aid of the above method, it can be diagnosed which genes are active in a tumor, for example. From this, conclusions as to the kind of tissue change and the like can be drawn. 
         [0015]    For preventing drying and for realizing a uniform distribution of the DNA molecules, it is known to close the object carrier by a lid, for example, such that a sample chamber is formed between the object carrier and the lid. Then, the sample chamber is vibrated by a vibration means to effect a movement of the two samples. This movement helps the corresponding sample components to find the suitable counterparts with which they then combine. Providing a vibration means has the disadvantage that stationary waves are produced and thus only a limited movement of the sample occurs. 
         [0016]    The problems described in the example above also exist in other analyses of chemical and/or biological samples in which one sample, for example, firmly adheres to a base portion at the object carrier and another sample is to react on it. 
         [0017]    Further, from PCT/EP02/02900 an analyzing device comprising a base portion and a head portion or a lid is known. The base portion and the head portion form a sample chamber. The base portion may be a flat object carrier, for example, made of thin glass. Likewise, the object carrier or another sample carrier may be placed upon the base portion such that the sample carrier is arranged within the sample chamber. Further, this device comprises a moving means for moving the sample in the sample chamber. According to the disclosure, the device comprises a conveying means as a moving means. With the aid of the moving means, at least part of the sample is drawn off the sample chamber and subsequently returned to the sample chamber. Moving of part of the sample can be effected by moving the sample to and fro in that part of the sample is drawn off the sample chamber and returned in opposite direction to the sample chamber. For this purpose, at least one channel is preferably connected with the sample chamber, which channel is connected with a pump or another conveying means for moving the sample to and fro. Another possibility for moving the sample in the sample chamber is to circulate the sample. In this case at least part of the sample is drawn off via a discharge channel and returned to the sample chamber via a supply channel. In this case the sample is conveyed in the same direction. 
         [0018]    By providing a moving means for the sample, occurrence of stationary waves is prevented. Drawing off and supplying at least part of the sample ensures that the entire sample quantity present in the sample chamber is moved. This is ensured in the case of both moving at least part of the sample to and fro and circulating at least part of the sample. 
         [0019]    When the device described in PCT/EP02/02900 is used, an undesired cooling of the sample, in particular the conveyed part of the sample, may occur. This phenomenon occurs in particular in the analysis of chemical and/or biological samples which must have, for example, a temperature of up to 75° C. in the sample chamber. Further, it was noted that heating of the sample chamber, in particular through components made of glass, leads to a delay in the temperature control and possibly to inexact sample temperatures. This is in particular due to the poor heat conductivity of glass. Further, it was noted that it is not possible to make the base portion and/or the head portion from steel, high-grade steel, aluminum, copper or compounds/alloys therefrom, e.g. anodized aluminum, brass. Although these materials have good heat conductivity, they are attacked by numerous samples. 
         [0020]    It is an object of the disclosure to provide device for examining chemical and/or biological samples, wherein the sample temperature is adjustable. 
       SUMMARY OF THE DISCLOSURE 
       [0021]    The device according to the disclosure comprises a sample chamber formed by a first portion and a second (head) portion. For changing the temperature of the sample, according to the disclosure a heating and cooling element is connected with the second (head) portion. According to the disclosure, a side of the second (head) portion defining the sample chamber is made from a material with high resistance to the sample and good temperature conductivity. This allows the sample temperature to be maintained within a narrow specified temperature range via the heating and cooling element connected with the sample portion. The temperature variation preferably lies in a range of ±1° C. Further, provision of a sample-resistant material according to the disclosure ensures that, for example, the analysis results are not falsified by part of the sample being separated from or washed out of the second (head) portion. 
         [0022]    Preferably, the material is resistant to deionized or distilled water. Preferably, the material is resistant to aqueous solutions, preferably saline solutions up to the solubility limit, preferably haloides, carbonates, sulfates, nitrates, hydroxides, borates, silicates, amines, amides, phosphates, hydrogen phosphates and dihydrogen phosphates, preferably of the alkali and alkaline earth metals, e.g., but not limited to, NaCl, CaCl 2 , MgCl 2 , NaOH, ethylenediaminetetraacetate (EDTA), tetraethylammonium chloride. 
         [0023]    Preferably, the material is resistant to organic acids and bases as well as their salts, e.g., but not limited to, formic acid, acetic acid, citric acid, sodium citrate, ammonium acetate. 
         [0024]    Preferably, the material is resistant to water-soluble polymers, e.g., but not limited to, sodium dextransulfate, poly(ethylene glycol), polyacrylamide. 
         [0025]    Preferably, the material is resistant to detergents, preferably ionic detergents, e.g., but not limited to, sodium dodecylsulfate (SDS) or Tween. 
         [0026]    Preferably, the material is resistant to organic solvents, e.g., but not limited to, chloroform, preferably polar solvents, e.g., but not limited to, dimethylformamide (DMF), formamide, dimethyl sulfoxide (DMSO), dimethylsulfide (DMS), ketones, e.g., but not limited to, acetone, alcohols, preferably methanol, ethanol, propanol, isopropanol, butanol, isobutanol, phenol, polyalcohols, preferably glycol, glycerol. 
         [0027]    The resistance exists preferably in a temperature range from −196° C. to 500° C., preferably from −80° C. to 200° C., preferably from −20° C. to 150° C., preferably from 4-100° C. 
         [0028]    Preferably, the resistance lasts for at least 12 hours, preferably, the resistance allows repeated use of the head portion. 
         [0029]    Preferably, the material is characterized by a loss of weight of less than 10 mg/m 2  per hour. In additions, the concentration of ions dissolved from the material, for example. by pitting/corrosion, should not affect the reaction in the chamber or the movement of the sample. This would happen if there is a reaction with one of the components in the chamber (e.g. denaturation of proteins or strand breaks of DNA), changing the pH of the buffer composition or inhibition of reaction or binding. 
         [0030]    Preferably, materials having a mechanical load-bearing capacity are used. Preferably, hard materials having a Vickers hardness [HV] of at least 10, preferably more than 20, preferably more than 50, preferably more than 100, preferably more than 500 are used. Preferably, the material has a yield strength 0.2 % of at least 10 MPa, preferably more than 100 MPa, preferably more than 200 MPa, preferably more than 500 MPa, preferably more than 1000 MPa. Preferably, the material has a bending strength of at least 10 MPa, preferably at least 50 MPa, preferably at least 100 MPa, preferably at least 500 MPa, preferably at least 1000 MPa. 
         [0031]    Preferably, the material has a good heat conductivity. Preferably, the heat conductivity exceeds 10 W/mK. Preferably, the heat conductivity exceeds 100 W/mK. 
         [0032]    Preferably, the material, from which in particular the overall second (head) portion is made, is selected such that it offers good dimensional accuracy. Thus it can be ensured that the volume of the sample chamber is defined and constant. Preferably, the manufacturing tolerances of the surface defining the sample chamber are smaller than 20 μm, preferably smaller than 10 μm, preferably smaller than 5 μm and preferably less than twenty percent of the smallest inner dimension of the chamber. Preferably, the mean linear thermal expansion coefficient α 30-1000  lies in the range from 1-10*10 −6 /K, or in the range of 10 −3 /K-10 −9 /K, or in the range of 10 −4 /K-10 −8 /K, or in the range of 10 −5 /K-10 −7 /K. 
         [0033]    Further, the material used is preferably selected such that little or no interaction occurs between the sample and the material. Preferably, the surfaces do not comprise any reactive groups which form a covalent or coordinate bond with amine groups, thiol groups or hydroxyl groups. Preferably, the surface is uncharged. Preferably, the surface does not comprise any groups which may form hydrogen bridge bonds (hydroxyl groups, amine groups or thiol groups). 
         [0034]    Preferred materials from which at least one side of the second (head) portion defining the sample chamber, and preferably the overall head portion are made include: heat-conductive plastic materials, preferably CoolPoly E1501 polypropylene (Cool Polymers, Inc.), graphite, diamond, ceramic, metals, preferably aluminum or copper, alloys, preferably brass. Graphite, metals or alloys are preferably used in combination with a protective layer. Preferred protective layers are silicate coatings, parylene, diamond-like carbon, Teflon, silicon carbide, silicon nitride or boron nitride. 
         [0035]    Particularly preferred is the use of ceramic, in particular non-oxide ceramics, in particular borides, carbides, nitrides and silicides (e.g. TiC, TaC, WC, TiN, TaN, TiB 2 , MoSi 2 ), in particular aluminum nitride, boron nitride, boron carbide, silicon nitride, silicon carbide, further hard-material mixed crystals (e.g. TiC—WC, TiC—TaC—WC, TiC—TiN) as well as double carbides and complex carbides (e.g. CO 3 W 3 C, Ni 3 W 3 C). 
         [0036]    Preferably, the second (head) portion preferably comprises a flat surface extending in the direction of the sample chamber. Since in a particularly preferred embodiment the first portion is also flat and arranged in parallel to the inside of the second (head) portion, it is ensured that inside the sample chamber the sample has a uniform thickness and/or height. 
         [0037]    In a particularly preferred embodiment, the second (head) portion is connected via an intermediate element with the temperature-control element. The intermediate element is made from a material with good heat conductivity, in particular from metal, and in a particularly preferred variant from aluminum. In a particularly preferred embodiment, the preferably provided channels for conveying and/or circulating the sample pass through the intermediate element. Due to the good heat conductivity of the intermediate element, the intermediate element serves as a heat accumulator such that the sample temperature is also equalized in the channels arranged in the intermediate element. To prevent interaction between the sample and the material of the intermediate element, preferably flexible conduits made of a suitable material are arranged in the channel. Also, the channels of the intermediate element may coated with a sample-resistant material. 
         [0038]    The second (head) portion preferably comprises at least one channel through which sample liquid can be supplied to the sample chamber and/or discharged from the sample chamber. In a particularly preferred variant, the second (head) portion comprises on the side facing the sample chamber elements and/or a mechanically molded surface, e.g. grooves, and/or a chemically molded surface, e.g. differently hydrophobic zones, which provide for a uniform overflow, intermixing, homogenization and/or distribution of the liquid in the sample chamber. Preferably, the supply and/or discharge channels comprise a transverse channel connected with the respective channel, wherein the transverse channel is preferably configured as a slot or a groove and is open over its overall length in the direction of the sample chamber. This configuration allows for better movement and homogenization of the sample. 
         [0039]    Preferably the aspect ratio of the thickness of the chamber to the width of the chamber is between 19:60 and 21:71, and more preferably 21:63. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0040]    Hereinafter, the disclosure will be explained in detail with respect to a preferred embodiment with reference to the accompanying drawings in which: 
           [0041]      FIG. 1  shows a schematic top view of a preferred embodiment of the receiving device with several inserted base portions, 
           [0042]      FIG. 2  shows a schematic sectional view of a first preferred embodiment taken along the line II-II of  FIG. 1 , the head portion not illustrated in  FIG. 1 , an intermediate element and a temperature-control element being additionally illustrated, 
           [0043]      FIG. 3  shows a schematic sectional view of a second preferred embodiment in principle corresponding to the embodiment shown in  FIG. 1 , 
           [0044]      FIG. 4  shows a schematic top view of a preferred embodiment of the head portion on the side facing the sample chamber, 
           [0045]      FIG. 5  shows a schematic sectional view taken along the line V-V of  FIG. 4 , 
           [0046]      FIG. 6  shows a schematic sectional view of a preferred embodiment of the head portion in connection with the intermediate element and the temperature-control element, and 
           [0047]      FIG. 7  shows a schematic sectional view along line VII-VII of  FIG. 6 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0048]    A receiving device  10  for several object carriers  12  comprises a portion  14 . The portion  14  is connected with centering elements  16 , 18 ,  20 . In the illustrated embodiment, the centering elements  16 , 18 , 20  are arranged such that four rectangular receiving areas  22  are formed in each of which an object carrier  12  can be arranged. The centering elements  16 , 18 , 20  have two opposing shorter side walls  16  and two likewise opposing longer side walls  18  arranged between the side walls  16 . In the illustrated embodiment, three partition walls  20  arranged in parallel to the shorter side walls  18  are provided between the side walls  18 . 
         [0049]    On the lower sides  24  of the centering elements  16 , 18 , 20 , the bottom portion  14  configured as a diaphragm is mounted. The receiving areas  22  hence have a flexible diaphragm as a bottom on which one object carrier  12  each is supported. Thus, it is possible to press from below against the diaphragm, as shown in  FIG. 2 , in order to horizontally align the object carrier, for example. 
         [0050]    On their insides  23 , i.e. on the sides facing the receiving areas  22 , the centering elements  16 , 18 , 20  are chamfered. Thereby, the opening pointing upwards in  FIG. 2  of the individual receiving areas is upwardly enlarged. This facilitates the insertion of the object carriers  12  into the receiving areas  22 . 
         [0051]    A head portion  26  according to the disclosure is configured such in a first embodiment ( FIG. 2 ) that it projects into the individual receiving areas  22  formed between the centering elements  16 , 18 , 20 . To this end, the lid  26  comprises four projections  28  in the illustrated embodiment, which have a substantially rectangular cross-section. The side walls  30  of the projections  28  abut on the inner walls of the web-shaped centering elements  16 , 20 . Likewise, side walls of the projection  28  not illustrated in  FIG. 2  abut on the web-shaped centering elements  18 . On the underside of the lid  26  facing the base portion or sample carrier  12 , for each receiving area 22 frame-shaped projections  32  are provided or formed by an additional component. The frame-shaped projection is configured as a circumferential projection. On an underside  34  of the frame-shaped projection  32 , a seal  36  is provided which is also configured a circumferential seal. The seal  36  rests on an outer edge of the sample carrier  12  und seals the sample carrier towards the lid  26 . Due to the frame-shaped projection  32 , a sample chamber  38  is formed between an inner side of the lid  36  and the sample carrier  12  within the frame-shaped projection  32 . In an alternative configuration the base portion is on top and the head portion. 
         [0052]    The head portion  26 , is below the base portion preferably made from ceramic material, is connected, on its side facing away from the sample chambers  38  with an intermediate element  27 . The intermediate element  27  is made from a material with good heat conductivity, in particular from aluminum. On the upper side facing away from the head portion  26  of the intermediate element  27  a temperature-control element  29 , such as a Peltier element, is arranged. Preferably, the temperature-control element  29  substantially extends over the overall surface of the intermediate element  27  such that the intermediate element  27  is uniformly heated. The intermediate element  27  transfers the heat to the head portion  26  which also has a good heat conductivity. 
         [0053]    For moving samples provided in the sample chamber  38 , two channels  40 , 42  connected with the sample chamber  38  are provided in the lid  26 . The channel  40 , for example, is connected via a flexible conduit  44  to a pump  46 . Correspondingly, the channel  42  is connected via a flexible conduit  48  with a pump  50 . The two pumps  46 , 50  are controlled by a preferably common control unit. The pumps  46 , 50  alternately draw part of the sample located in the sample chamber into the channel  40  and  42 , respectively, and subsequently return it into the sample chamber  38 . Thereby, movement of the sample in the sample chamber  38  is realized such that, for example when the device is used for analyzing DNA molecules, the probability of an interaction and thus the bonding of marked DNA strands with the surface-bound DNA strands is increased. 
         [0054]    The flexible conduits  44 , 48  connected with the channels  40 , 42  pass through the intermediate element  27  and through the temperature-control element  29 . Provision of a flexible conduit which passes through the intermediate element  27  ensures that no interaction occurs between the material of the intermediate element  27  and the sample. Further, it is ensured that the sample is also heated inside the flexible conduit, if possible. If necessary, the flexible conduits  44 , 48  may, in the exposed area, be surrounded and/or jacketed by an insulation and/or a heat-conductive layer connected with the temperature-control element  29 . 
         [0055]    Further, two receiving chambers  52 , 54  are provided within the head portion  26 . The receiving chamber  52  is connected with the channel  40 , and the receiving chamber  54  is connected with the channel  42 . Due to the size of the receiving chambers  52 , 54 , the sample quantity taken from the sample chamber  38  can be collected. It is also possible that the two pumps  46 , 50  are directly connected with the receiving chambers  52 , 54  and are possibly arranged within the lid  26  or on the upper side thereof. 
         [0056]    For supplying a sample to the sample chamber  38 , a further channel  56  connected with the sample chamber  38  is provided in the lid  26 , which channel  56  may also pass through the intermediate element  27  and the temperature-control element  29 , but preferably bypasses these elements. After the lid  26  has already been set upon the receiving device  10 , samples can be supplied through this channel  56  into the sample chamber  38  which is already tightly sealed. Likewise, the sample can be supplied through one of the two channels  40 , 42 , which is possibly branched for this purpose. 
         [0057]    For improving the movement in the sample chamber  38 , the channels  40 , 42  may be branched such that a plurality of channels  40 , 42  are connected with the sample chamber  38 . Further, it is possible to provide a plurality of channels  40 , 42  per sample chamber  38  in the lid  26 . Preferably, half of the channels are connected with the same pump. 
         [0058]    The lid  26  and the sample carriers  12  are held in respective holding devices not shown. In  FIG. 2 , one and/or both holding devices can be vertically, transversely or arcuately moved. Because of the movement of one and/or both holding devices together with the lid and the sample carriers  12 , respectively, an automatic fitting of the lid  26  into the receiving areas of the receiving device  10  and/or an automatic fitting of the receiving areas of the receiving device  10  relative to the lid  26  is possible. 
         [0059]    In this case, the seal  36  provided at the frame-shaped projections  32  is pressed upon an edge portion of the sample carriers  12 , and the sample chamber  38  is formed. Since the sample carriers  12  are supported on an elastic planar bottom portion  14  or a diaphragm serving as bottom portion  14 , damaging the sample carriers by lowering the lid  26  is prevented. Further, the elastic support or the elastic diaphragm  14 , respectively, serves for ensuring a tight sealing between the lid  26  and the sample carriers  12 . 
         [0060]    The sample chamber  38  which, in the illustrated embodiment, substantially extends over the overall sample carrier  12  may be divided into a plurality of individual sample chambers. For this purpose, webs subdividing the sample chamber  38  are arranged on the lower side of the lid  26 . On the side of the webs facing the sample carrier  12  preferably seals corresponding to the seals  36  for sealing the individual sample chambers produced are provided. Each individual sample chamber produced is, as described above, preferably provided with channels  40 , 52 , 56  and has the corresponding preferred configuration. Each individual sample sub-chamber into which the sample chamber  38  is subdivided can thus be filled with hybridization liquid independent of adjacent sample chambers, and handled as described above. Due to the subdivision of the sample chamber  38  into a plurality of sample sub-chambers different samples can be analyzed in different ways using a standard object carrier  12 . In particular, identical samples taken e.g. from the bodies of different patients can be analyzed using the same hybridization liquids, or identical samples taken from the body of a patient can be analyzed using different hybridization liquids. In this connection it is particularly advantageous that commercial object carriers can be used as sample carriers  12 . 
         [0061]    A second preferred embodiment ( FIG. 3 ) comprises a lower area identical with that described with reference to  FIG. 2 . The lid or head portion  57  as well as both the intermediate element  76  and the temperature-control element  58  are of different configuration in this embodiment. Identical or similar components of the device are designated with the same reference numerals in  FIG. 3 . 
         [0062]    The head portion  57  comprises a supply channel  60  connected with the sample chamber  38  and a discharge channel  62  connected with the sample chamber  38 , said channels  60 , 62  bypassing the intermediate element  76  and the temperature-control element  58 . The channel  62  is connected via a valve  64  and a channel  66  with a pump  68 . The pump  68  is connected with the supply channel  66 . The valve  64  is further connected with a drain  70 . The channel  66  is connected via another channel  72  with a medium reservoir  74 . The arrangement of the pump  68 , the valve  64 , the medium reservoir  74 , including the connecting channel  72 , as well as the sample chamber  38  in the circuit comprising the sample chamber  38 , the valve  64 , the pump  68  and the channels  60 ,  62  and  66  may be varied according to requirement. 
         [0063]    The position of the valve  64  can be e.g. selected such that the sample in the sample chamber  38  is circulated. The sample is thus drawn off the chamber  38  via the discharge channel  62 , supplied via the channel  66  to the pump  68  and then supplied via the channel  66  back to the sample chamber  38 . 
         [0064]    The position of the valve  64  may, for example, be selected such that the sample contained in the sample chamber  38  is circulated. The sample is thus drawn off the chamber  38  via the discharge channel  62 , supplied via the channel  66  to the pump  68 , and then returned via the channel  66  to the sample chamber  68 . 
         [0065]    For discharging a portion of the sample via the drain  70 , the valve  64  may be arranged in an intermediate position such that a portion of the sample fed via the channel  62  to the valve  64  is supplied to the channel  70 , and another portion is supplied to the cannel  66 . 
         [0066]    Further, it is possible to set the valve  64  such that the channel  66  is closed and the entire sample is supplied towards the drain  70 . For this purpose, new sample liquid is supplied with the aid of the pump  68  from the reservoir  74  to the sample chamber  38 , and the sample contained therein is pressed out of the sample chamber  38 . To allow the entire sample to be exchanged, the channel  66  must also be emptied. For this purpose, the valve  64  is switched over after evacuation of the sample from the sample chamber  38  such that the sample remaining in the channel  66  is pressed at least up to and into the channel  70 . Subsequently, the valve  64  is opened again and the sample contained in the channel  66  of the sample chamber  38  and the channel  62  is pressed into the drain  70 . 
         [0067]    With the aid of the temperature-control element  58 , preferably a Peltier element, the temperature of the sample contained in the sample chamber  38  can be equalized via the intermediate element  76  and the head portion  57 . This is effected as described above with reference to  FIG. 2 . 
         [0068]    Preferably, a separate pump  68  is provided for each of the four sample chambers  38  of the illustrated embodiment. Preferably, only one medium reservoir is provided for a plurality of, in particular for all sample chambers  38 . For a separate sample exchange in the individual sample chambers  38  correspondingly controllable valves are provided in the channels. 
         [0069]    An particularly preferred embodiment of a ceramic head portion  80 , which is suitable for defining a single sample chamber, is shown in  FIGS. 4 and 5 . The head portions  26  and  57 , respectively, may be configured analogously to the head portion  80 . 
         [0070]    The head portion  80  is of substantially rectangular configuration and comprises two through-going channels  82 , 84 . The channels  82 , 84  have, for example, the function of the channels  40  and  42  described with reference to  FIG. 2 , or the function of the channels  60 , 62  described with reference to FIG.  3 . On a side  86  of the head portion  80  facing the sample, i.e. at a side wall of the sample chamber  38 , two transverse channels  88  are provided in the head portion  80 , said transverse channels  88  being connected with a through-going channel  82  and  84 , respectively. The transverse channels  88  are designed for a uniform flow through the sample chamber  38  and a better intermixing, homogenization and/or distribution of the sample. 
         [0071]    On the side of the head portion  80  opposite the transverse channels the channels  82 , 84  have an enlarged diameter. The cylindrical expansion of the channels  82 , 84  serve for receiving the flexible conduits  44 , 48  ( FIG. 2) and 66  ( FIG. 3 ), respectively, connected with the pumps and possibly the valves. The flexible conduits arranged in these receiving openings  90  preferably bypass the intermediate element  27  and  76 , respectively, as well as the temperature-control element  29  and  58 , respectively. 
         [0072]    Further, in the illustrated embodiment, the head portion  80  comprises a supporting element  92  configured as a circumferential projection. Due to the exact construction of the supporting element  92  the height of the sample chamber  38  can be defined with high accuracy. The distance between the head portion  80  and  26 , 57 , respectively, ( FIG. 2  and  FIG. 3 ) and the object carrier  12  is set by a frame with a defined height. This frame can further be connected with the sealing element  36  shown in  FIG. 2  and  FIG. 3 . Alternatively, the circumferential projection can be configured as a raised portion, as shown in  FIG. 2  and  FIG. 3 , which directly defines the distance between the head portion  80  and  26 , 57 , respectively ( FIG. 2  and  FIG. 3 ), and the object carrier  12 . 
         [0073]    In another preferred embodiment ( FIGS. 6 and 7 ), the head portion  80  corresponds to the head portion described with reference to  FIGS. 4 and 5 . The head portion  80  has connected thereto an intermediate element  94  preferably made of aluminum. An upper side of the intermediate element  94  facing away from the head portion  80  has connected thereto a temperature-control element  96 . 
         [0074]    In contrast to the embodiments described above, the channels and/or flexible conduits do not extend substantially vertically through the intermediate elements  76  and  27 , respectively, as well as the temperature-control elements  58  and  29 , respectively. Rather, in this preferred embodiment, channels and/or bores  98 , 100 , 102 , 104  are provided in the intermediate element  94 . Here, the bores, as shown in  FIGS. 6 and 7 , are arranged such that a flexible conduit  106  disposed inside the bores passes substantially horizontally over a long distance through the intermediate element  94 . This offers the advantage that the sample contained in the flexible conduit is kept at a constant temperature by the intermediate element  94 . 
         [0075]    According to the embodiment involved ( FIG. 2  or  FIG. 3 ), the pumps and valves are arranged laterally next to the intermediate element  94  and/or connected with the lateral outlet openings  108  and  110 . 
         [0076]    In the embodiments described above, the base (first) portion ca be located above the second (head) portion.