EP0711603A1 - System for incubating sample fluids - Google Patents

Abstract

A system for the incubation of sample liquids, consists of a rack (10) where incubation vessels (20) are located in holding plate (3) bore holes (12), an incubation block (1) with bore holes (2) for the vessels, and an arrangement for tempering the incubation block, which is thermally connected to the latter. The holding plate bore holes and the incubation block bore holes, are geometrically arranged so the incubation vessels of the rack fit into the incubation block bore holes.

Description

• ein Rack, bei dem Inkubationsgefäße in Bohrungen einer Halteplatte eingehängt sind,
• einen Inkubationsblock mit Bohrungen zur Aufnahme von Inkubationsgefäßen,
• eine Vorrichtung zur Temperierung des Inkubationsblockes, die thermisch mit dem Inkubationsblock verbunden ist,

wobei die Bohrungen in der Halteplatte und die Bohrungen im Inkubationsblock so aufeinander abgestimmt sind, daß sich die Inkubationsgefäße des Racks in die Bohrungen des Inkubationsblockes einpassen, wenn das Rack auf den Inkubationsblock gestellt wird.The present invention relates to a novel system for the incubation of sample liquids, which has the following elements

• a rack in which incubation vessels are suspended in the bores of a holding plate,
• an incubation block with holes for receiving incubation vessels,
• a device for tempering the incubation block, which is thermally connected to the incubation block,

the bores in the holding plate and the bores in the incubation block being matched to one another in such a way that the incubation vessels of the rack fit into the bores of the incubation block when the rack is placed on the incubation block.

Systems for the incubation of sample liquids are used in particular in the field of clinical diagnostics. To carry out many diagnostic methods, it is necessary to run reactions at a predetermined temperature in order to be able to control the reaction rate. However, incubation of sample liquids is not used exclusively to carry out an analytical reaction; rather, incubators are also used to multiply organisms such as bacteria, yeasts, fungi, viruses etc. present in sample liquids in order to subsequently be able to determine the increased organisms. Incubators are also used, for example, to multiply DNA or RNA. The corresponding devices are called thermal cyclers.

Devices for the incubation of sample liquids have been known for a long time in the prior art. The known devices can basically be divided into two classes. The first class includes incubators in which the sample vessels are heated by a fluid phase. Devices of this type are described, for example, in EP-A-0 363 143 and EP-B-0 087 028. In the two documents mentioned, devices are described in which sample vessels are located in a holder and are immersed in a liquid with this holder. The temperature of the sample vessels or sample liquids is controlled by the liquid inside the incubator. Due to the fluid properties of the liquid phase, the liquid adapts perfectly to the shape of the incubation vessels.

The second class of incubation devices includes so-called metal block incubators in which there are bores within an incubation block made of heat-conducting material, which serve to hold incubation vessels. Such incubation devices are known for example from EP-A-0 151 781 or US-4,335,620. Reference is hereby made in full to the two documents mentioned.

US 4,335,620 describes an incubator which has a solid block made of a thermally conductive material such as e.g. B. aluminum. The block serves both to hold sample vessels and as a heat sink for temperature control of the vessels. The document relates to a special design for thermally isolating the device from the environment. The total heat loss of the equipment is minimized.

Document US-4,727,034 relates to a device for thermostatting sample liquids. The vessels with sample liquids are placed in a rack made of a good heat-conductive material. The rack in turn is clamped in the device between two side walls, at least one of which is heated, so that the temperature of the rack and thus the sample liquids in the vessels is possible.

Each of the two classes of incubators mentioned has its own advantages and disadvantages. When using fluids for heat transfer, arrangements of incubation vessels that are contiguous can be used. This makes it possible to put a large number of vessels in the heat bath at the same time dive. A disadvantage of these types of incubation, however, is that the fluids adhere to the outer walls of the incubation vessels. When removing the incubation z. B. for subsequent analysis steps, this liquid drips off and leads to contamination of the device. It is even more disadvantageous if liquid or liquid adhering to the vessels is sprayed out of the incubator and leads to a disturbance in the analysis. Overall, the handling of moist test tubes is disadvantageous and should therefore be avoided.

The mentioned disadvantages do not have metal block incubators, but this type of incubator itself has other disadvantages. To ensure good heat transfer between the sample liquid and the incubator, it must be ensured that the incubation vessels come into direct contact with the incubator over as large an area as possible in order to ensure good heat transfer. With the incubators described in US Pat. Nos. 4,335,620 and 4,727,032, this requirement is achieved in that the device has bores within the incubator which correspond in shape to the incubation vessels. The reagent tubes and the holes in the incubator must therefore be precisely coordinated. Due to the mechanical conditions, it has not been possible to insert an arrangement consisting of several vessels into a metal block incubator without jamming.

The object of the invention was to eliminate this disadvantage of metal block incubators and to propose an incubation device which combines the advantages of metal block incubators and fluid incubators. In particular, it was the object of the invention to propose a system for incubation which does not require the use of fluids for heat transfer and which enables incubators to be easily, quickly and reliably equipped with a large number of incubation vessels.

• ein Rack, bei dem Inkubationsgefäße in Bohrungen einer Halteplatte eingehängt sind,
• einen Inkubationsblock mit Bohrungen zur Aufnahme von Inkubationsgefäßen,
• eine Vorrichtung zur Temperierung des Inkubationsblockes, die thermisch mit dem Inkubationsblock verbunden ist,

wobei die Bohrungen in der Halteplatte und die Bohrungen im Inkubationsblock so aufeinander abgestimmt sind, daß sich die Inkubationsgefäße des Racks in die Bohrungen des Inkubationsblockes einpassen, wenn das Rack auf den Inkubationsblock gestellt wird.This problem is solved by a system for the incubation of sample liquids, which has the following elements:

• a rack in which incubation vessels are suspended in the bores of a holding plate,
• an incubation block with holes for receiving incubation vessels,
• a device for tempering the incubation block, which is thermally connected to the incubation block,

the bores in the holding plate and the bores in the incubation block being matched to one another in such a way that the incubation vessels of the rack fit into the bores of the incubation block when the rack is placed on the incubation block.

Sample liquids for incubation are to be understood as meaning blood samples, serum samples, urine, food samples, water samples, reaction batches and the like. In particular, those liquids are also included which are obtained from sample materials by adding reagents. For example, DNA-containing samples should also be included, which are mixed with reagents to amplify the DNA.

A system according to the invention can be used in particular for chemical and clinical chemical analysis, since in this area the maintenance of certain temperatures or the pretreatment of samples at certain temperatures is of crucial importance for the reliability of the analysis results. A system for incubation according to the invention can also be used, for example, as a so-called thermal cycler, which is used in the amplification of DNA.

Incubation is to be understood as the temperature control of sample liquids over a certain period of time with a predetermined temperature profile. In the most frequently used incubators, the incubation block has a precisely defined temperature that can be kept constant over a long period of time. In this case, the incubation is started by inserting the incubation vessel into the incubation block and ended by removing the incubation vessel from the block. However, the invention also provides for the temperature of the incubation block to be controlled as a function of time. In this way, a sample liquid can be exposed to changing temperatures during the presence of the incubation vessel in the incubation block. Temperatures that change over time are used, for example, in so-called thermocyclers for amplifying DNA using the "polymerase chain reaction".

A system for the incubation of sample liquids in the sense of the invention can represent a so-called "stand-alone module" or a sub-unit within an analysis device. The part of the incubation system that has holes for receiving incubation vessels is referred to as the incubation block. Incubators according to the invention therefore belong to the class of metal block incubators. The incubation block is preferably made from one piece, for example from a cylinder, into which holes are made or by pouring a material into a mold that provides recesses for incubation vessels. Suitable materials for the incubation block are metals, in particular aluminum and also alloys, such as brass.

The bores within the incubation block are usually cylindrical in shape or are truncated cones. The term "cylinder" is intended to encompass both cylinders with a round and an angular cross section. The bores are usually a few centimeters deep and preferably taper towards the inside of the incubation block.

The incubation block can furthermore have guide elements which facilitate the positioning of a rack according to the invention. Inside the incubation block or on its outside there can be sensors (e.g. light barriers) that detect the presence of a rack.

The incubation block is still in thermal contact with a temperature control device. If the incubation block is only intended for heating incubation vessels above room temperature, this temperature control device can be a simple electrical heater. However, it is advantageous to provide a possibility for cooling the incubation block in addition to a heating element. Cooling can be achieved, for example, by a part of the incubation block through which cold water flows. For larger incubation systems, a heat pump similar to a refrigerator can also be used for cooling. Devices with which both heating and cooling are possible are Peltier elements that transport heat by means of electrical energy.

Said device for tempering the incubation block can either be thermally coupled to the incubation block, as shown, for example, in No. 4,335,620, or the means for tempering can be located within the incubation block itself.

Within the incubation block, preferably near the bores for the incubation vessels, there can be temperature detectors with which the setting of the desired temperature can be checked. The regulation of the devices for temperature control is well known in the prior art. For the description of a temperature control, reference is made here in full to the European patent specification EP-B-0 273 969.

The incubation block has a number of bores open at the top, which are usually arranged periodically. In the prior art, these bores are equipped with incubation vessels either manually or with the aid of a robot arm. While manual assembly is time-consuming and personnel-intensive, a device for automatic assembly makes a device relatively complex and therefore expensive. Even with automatic assembly, incubation vessels must be fed to the device from the outside in a form that is suitable for robotics.

In the present invention, the incubation block is equipped with the aid of a rack in which incubation vessels are located. According to the invention, the incubation vessels hang in the bores of a holding plate. The bores within the holding plate are arranged corresponding to the bores within the incubation block. To equip the incubation block with incubation vessels, the rack is moved over the incubation block and lowered there, so that the incubation vessels move into the holes in the incubation block.

A holding plate according to the invention has the shape of a thin disc in which holes are made which serve to hold incubation vessels. The holding plate can be made from a variety of dimensionally stable materials. Metals and especially plastics can be used. The arrangement of the holes in the holding plate corresponds to the arrangement of the holes on the top of the incubation block used in each case. A holding plate can for example be a full circle or preferably a segment of a circle or a section of a circular disk. The thickness of the holding plate must be such that it ensures mechanical stability when incubation vessels are hanging in the holding plate. If the holding plate is made of plastic, then the material thickness usually be one to several millimeters. Of course, a reduction in the material thickness is possible if struts are installed that increase the mechanical stability.

The bores within the holding plate can be made with tools in a holding plate made of solid material or they are already provided in the mold for producing the holding plate. According to the invention, the cross section of these bores is of some importance, so that the tolerances for the bore cross section should be less than 0.05 mm.

When selecting the materials for the holding plate, poorly heat-conducting materials are preferred, since in a preferred embodiment the holding plate comes to lie directly on the incubation block. Poorly heat-conducting holding plates therefore reduce the heat loss of the incubation block to the environment.

Stand elements can preferably be located on the underside of the holding plate, which ensure that the incubation vessels which hang in the holding plate do not hit the surface. The stand elements make the holding plate a frame in which the incubation vessels can also be stored outside of an incubation device. This is particularly important if the holding plate is to be equipped with incubation vessels at the factory. In this case, the stand elements enable a simpler packaging of the holding plate with the incubation vessels and furthermore easier handling for the user.

Tabs can be attached to the top of the holding plate, which a user can grip when he wants to transport the rack. The tabs are particularly helpful when inserting the rack into the incubation block, since gripping the holding plate itself would be uncomfortable here.

Incubation vessels are preferably inserted in the bores of the holding plate at the factory. However, the user can also manually equip the holding plate with incubation vessels. Incubation vessels are already widely known in the prior art. Reusable incubation tubes are usually made of glass, while single-use tubes are usually made of plastics. Suitable plastics are, for example, polyethylene, polypropylene. Polystyrene and polymethyl methacrylate. The shape of the incubation tubes usually corresponds to that of tubes with an open and a closed end. As already described above, it is important for the use of incubation vessels in incubation blocks with bores that the outside of the incubation vessels bears against the inner wall of the bores in order to ensure the best possible heat transfer. Tubes which are tapered towards their closed end, ie towards the underside, are preferred for incubation vessels. It has been found that a taper with a slope of 0.05 to 0.5 is particularly favorable for manufacturing reasons. According to the invention, the incubation vessels furthermore have holding devices which prevent the incubation vessels from slipping through the bores in the holding plate. The incubation vessels hang in the holding plate with their closed end pointing downwards. It is possible to hold the incubation vessels if the incubation vessels are tapered and the open end has a cross section which is larger than the cross section of a bore in the holding plate. If such an incubation vessel is introduced into a bore, it slips through until it is at a point where the outer cross section corresponds to the bore diameter. The incubation vessel and holding plate are jammed at this point.

According to the invention, however, it is preferred if the incubation vessel has holding elements which specify a better-defined holding position of the incubation vessel within the holding plate. These holding elements can be webs, for example, which are attached to the outer peripheral surface of the incubation vessel and which cause the effective cross section to suddenly widen at a certain height of the incubation vessel. It is particularly preferred if the incubation vessel is constructed in such a way that a plateau exists which is essentially perpendicular to the longitudinal axis of the incubation vessel and with which the incubation vessels rest on the holding plate. Such a plateau can be generated, for example, by a circular ring which extends around the incubation vessel or the incubation vessel can have a lower part, the cross section of which is smaller than the cross section of the bores and a second part is located on this part, the cross section of which is larger than that Bore cross section. The two parts are preferably connected to one another by a piece of material, preferably perpendicular to the longitudinal axis of the incubation vessel. This connecting piece forms the plateau, which rests on the holding plate.

According to the invention, the ratio of the bore cross section and the outer circumference of the incubation vessel, which is located at the level of the holding plate when the incubation vessel is suspended in the holding plate, is important. On the one hand, the incubation vessel must be held by the holding plate with sufficient accuracy within the plane of the holding plate so that the incubation vessels can be introduced into the bores of the incubation block in a targeted manner. On the other hand, the incubation vessel must have some play in the plane of the holding plate within the bore, so that geometrical deviations of the bores in the holding plate and the bores in the incubation block do not lead to jamming of the incubation vessels. A mechanical play between the incubation vessels and the holding plate is of particular importance in the case of incubators, since the temperature differences result in thermal expansions which, in the case of a rigid arrangement of incubation vessels and holding plate, lead to jamming if there is more than one incubation vessel. Even a slight jamming means that a tight fit of the incubation vessels on the inner walls of the bores of the incubation block is no longer guaranteed.

A suitable mechanical play can be obtained if the outer cross section of the incubation vessels in the region which is enclosed by the holding plate is 0.2 to 1 mm smaller than the inner cross section of the bores of the holding plate.

To ensure that an incubation vessel fits tightly within a bore, it is also advantageous if the part of the incubation vessel which is located below the holding plate is longer than the bores of the incubation block are deep. If the holding plate with the incubation vessels is placed on the incubation block, the incubation vessels hit the bottom of the bores and the devices are lifted off the holding plate. When using conically tapering incubation vessels, this leads to the play between the incubation vessel and the bore in the holding plate being increased, so that jamming can be avoided even better. In this embodiment, it is advantageous that the holding devices of the incubation vessels stand out from the holding plate. In this way, the incubation vessels are in close contact with the inner walls of the bores even when the incubation vessels exhibit length fluctuations in terms of production technology.

In a particularly preferred embodiment of the subject matter of the invention, the holding plate is supplied equipped with incubation vessels, so that the user only has to insert it into the incubation block.

The invention accordingly offers the advantage that the rack according to the invention can be used to easily equip incubators. The advantages of fluid incubators and metal block incubators can accordingly be combined by using a rack according to the invention. A simple assembly of an incubator with a large number of incubation vessels is possible without a large number of manual work steps being necessary, without requiring robotics, or without the disadvantages associated with fluids.

Figur 1a:

Aufsicht auf einen Inkubationsblock mit eingesetztem Rack

Figur 1b:

Teilausschnitt der Figur 1a in Seitenansicht

Figur 2:

Inkubationsgefäß

Figur 3:

Rack in seitlicher Darstellung

Figur 4a:

Perspektivische Darstellung eines teilweise bestückten Inkubationsblockes

Figur 4b:

Schematische Darstellung des Bestückungsvorganges

Figur 1a zeigt einen Inkubationsblock (1) in Aufsicht sowie in Figur 1b einen Detail-Querschnitt. Die Oberseite des Inkubationsblockes hat eine im wesentlichen kreisförmige Gestalt. Die Bohrungen (2) im Inkubationsblock sowie die Bohrungen (12) in der Halteplatte sind in vier konzentrischen Kreisen angeordnet. Die Halteplatte (3) besitzt im wesentlichen die Form eines Kreissegmentes und hat an ihrer Unterseite mehrere Standelemente (4a, 4b), die außerdem zur Positionierung der Halteplatte auf dem Inkubationsblock dienen. Die Standelemente (4a) besitzen einen winkligen Querschnitt, der in Zusammenwirkung mit den Aussparungen (5) im Inkubationsblock (1) zur Positionierung dient. Weiterhin besitzt die Halteplatte ein Standelement (4b), das in eine kreisförmige Ausnehmung (6) innerhalb des Inkubationsblockes (1) eingreift. Figur 1b zeigt, daß die Form des Inkubationsgefäßes (20) und die Bohrung (2) im Inkubationsblock (1) so aufeinander abgestimmt sind, daß die Wandung des Inkubationsgefäßes eng an der Innenseite der Bohrung (2) anliegt, um einen guten Wärmeübergang zu gewährleisten.The present invention is explained in more detail with reference to the figures:

Figure 1a:

Supervision of an incubation block with an inserted rack

Figure 1b:

Partial section of Figure 1a in side view

Figure 2:

Incubation vessel

Figure 3:

Rack in side view

Figure 4a:

Perspective view of a partially loaded incubation block

Figure 4b:

Schematic representation of the assembly process

FIG. 1a shows a top view of an incubation block (1) and a detail cross section in FIG. 1b. The top of the incubation block has a substantially circular shape. The bores (2) in the incubation block and the bores (12) in the holding plate are arranged in four concentric circles. The holding plate (3) has essentially the shape of a circular segment and has a plurality of standing elements (4a, 4b) on its underside, which also serve to position the holding plate on the incubation block. The stand elements (4a) have an angled cross section which, in cooperation with the cutouts (5) in the incubation block (1), serves for positioning. Furthermore, the holding plate has a stand element (4b) which engages in a circular recess (6) within the incubation block (1). Figure 1b shows that the shape of the incubation vessel (20) and the bore (2) in the incubation block (1) are matched to one another so that the wall of the incubation vessel lies closely against the inside of the bore (2) to ensure good heat transfer .

An incubation vessel (20) is shown enlarged in FIG. The incubation vessel (20) shown is in one piece, but can be divided into two sections. The section (21) tapers downwards and is closed at the bottom. The section (22), which is located above the holding plate (3) when the vessel is suspended in the holding plate, has a cylindrical shape and is open at the top. The transition between the two sections of the incubation vessel is of particular importance. Due to the different outside diameters of the sections mentioned, a plateau (23) is formed between them, with which the incubation vessel rests on the holding plate (3). The plateau (23) has a width of about 0.3 to 0.6 mm.

Figure 3 shows a rack (10) in side view with a suspended incubation vessel (20) and free bores (12). The two tabs (11) are located above the holding plate (3). Both the stand elements (4a) and the stand element (4b) can be seen below the holding plate (3).

FIG. 4a shows a system for incubation in a perspective view. A rack (10) is placed on the incubation block (1) in such a way that the incubation vessels (20) dip into the bores (2) of the incubation block. The stand elements (4a) slide over the edge of the recess (5) and the stand element (4b) enters the recess (6). A light barrier (24) can also be seen in FIG. 4a, which is located within the incubation block. The light barrier detects the presence of a rack in that a stand element (4b) interrupts the light path at the lower end of the recess (6). For clarification, a section of this figure is shown in side view in Figure 4b. It can be seen in these figures that the incubation vessel (20) is initially suspended in the rack (10). If the incubation vessel is inserted into a hole (2) in the incubation block (1) using the rack, the incubation vessel hits the bottom of the hole in the incubation block. The length of the incubation vessel (20) is dimensioned such that a gap is formed between the plateau (23) and the top of the holding plate (3) when the holding plate lies on the incubation block. In FIG. 4b it can also be seen that the space between the edge of the bore and the incubation vessel increases when the incubation vessel is pushed upwards out of the holding plate.

Reference list

(1)

Incubation block

(2)

Holes in the incubation block

(3)

Retaining plate

(4a, 4b)

Stand elements

(5)

Recess

(6)

circular recess

(10)

Rack

(11)

Handle straps

(12)

Holes in the holding plate

(20)

Incubation vessel

(21)

lower section of the incubation vessel

(22)

upper section of incubation vessel

(23)

plateau

(24)

Photoelectric barrier

Claims (20)

System for the incubation of sample liquids which has the following elements a rack (10), in which incubation vessels (20) are suspended in bores (12) of a holding plate (3), - an incubation block (1) with bores (2) for receiving incubation vessels, a device for tempering the incubation block, which is thermally connected to the incubation block, the bores in the holding plate (12) and the bores in the incubation block (2) are matched to one another in their geometrical arrangement so that the incubation vessels of the rack fit into the bores of the incubation block when the rack is placed on the incubation block. System according to Claim 1, in which the bores in the incubation block and the outer walls of the incubation vessels are matched to one another such that the outer wall of the incubation vessel lies closely against the inner wall of the bore of the incubation block. The system of claim 1 or 2, wherein the length of the portion of the incubation vessels that is below the holding plate is greater than the depth of the bores of the incubation block. System according to claim 1, wherein stand elements (4a, 4b) are attached to the underside of the holding plate and there are recesses in the incubation block for receiving these stand elements. The system of claim 1, wherein one or more tabs (11) are on the top of the support plate. System according to claim 1 or 4 with a sensor within the incubation block which detects the presence of a rack. System according to claim 1, wherein the holding plate has the shape of a segment of a circle or a part of an annulus. Rack (10) for equipping an incubation block (1) with incubation vessels (20), in which the incubation vessels are suspended in bores (12) of a holding plate (3) and the holding plate on its underside has standing elements (4a, 4b) that are longer than that part of the incubation vessels which is located below the holding plate, the incubation vessels having holding devices which prevent the incubation vessels from slipping through the bores in the holding plate. Rack according to Claim 8, in which the outer cross section of the incubation vessels in the region which is enclosed by the holding plate is smaller by 0.2 mm to 1 mm than the inner cross section of the bores of the holding plate. Rack according to Claim 8, in which the holding device for the incubation vessels is provided in that the incubation vessels have a part whose outer cross section is larger than the inner cross section of the bores in the holding plate. Rack according to Claim 10, in which the outer cross section of the incubation vessels is designed such that below the part whose outer cross section is greater than the inner cross section of the bores there is a plateau (23) which is essentially perpendicular to the longitudinal axis of the incubation vessel, and with which the incubation vessels lie on the holding plate. Rack according to claim 8 with incubation vessels, in which the part of the incubation vessels (20) tapers below the holding plate (3) with a slope of 0.05 to 0.5 towards the closed end of the incubation vessel. Rack according to claim 8 with one or more grip tabs (11) which are attached to the top of the holding plate. Use of a rack (10), which has a holding plate (3) with bores (12) in which there are incubation vessels (3), for equipping an incubation block (1) with bores (2) with incubation vessels in such a way that Rack is placed on the incubation block, with the incubation tubes fitting into the holes in the incubation block. Use of a rack according to Claim 14, in which stand elements (4a, 4b) which are longer than the part of the incubation vessels (20) below the holding plate (3) are attached to the underside of the holding plate. Use of a rack according to claim 14 or 15, in which the incubation vessels have holding elements which prevent the incubation vessels from slipping through the holding plate. Use of a rack according to claim 14 for equipping an incubation block, in which the rack is placed on the incubation block and the incubation vessels fit into the bores of the incubation block, the holding elements moving away from the holding plate when the incubation vessels and the holding plate are on the Incubation block. Procedure for the incubation of sample liquids in the a rack (10) with bores (12) within a holding plate (3), in which incubation vessels (20) hang, is placed on an incubation block (1) with bores (2) for receiving the incubation vessels, - The sample liquids are heated by heating or cooling the incubation block and - The incubation vessels (20) are either removed manually or all incubation vessels with the rack (10) are removed from the incubation block. The method of claim 18, wherein the rack (10) is manually loaded with incubation vessels (20) by the user. Method according to claim 18, in which the rack (10) is automatically equipped with incubation vessels (20) and the rack is made available to the user.

Images