WO2000029115A1

WO2000029115A1 - Devices and method for regulating the temperature of samples

Info

Publication number: WO2000029115A1
Application number: PCT/EP1999/008550
Authority: WO
Inventors: Thomas Altmann; Dietmar Kropp; Ulrich Schneider; Heinrich SPÖNTJES; Toralf Eifrig
Original assignee: MAX-PLANCK-Gesellschaft zur Förderung der Wissenschaften e.V.
Priority date: 1998-11-16
Filing date: 1999-11-08
Publication date: 2000-05-25
Also published as: AU1381300A; DE19852733A1

Abstract

The invention relates to devices and a method for tempering a liquid bath in a reaction vessel (10) with a medium whose temperature can be regulated with a heating circuit (20) and a cooling circuit (30), each of which have heating or cooling devices (23, 33a, 33b). The medium flows through a heat exchanger (12) in the reaction vessel (10) from an admission flow (14) to a return flow (15) and from the return flow (15) to the admission flow (14), in dependence on the operation of blocking devices (22, 35, 36), through the heating and/or cooling circuit (20, 30). The heating or cooling devices (23, 33a, 33b) and the blocking devices (22, 35, 36) are operated in such a way that the medium in the reaction vessel is at a predetermined desired temperature.

Description

Devices and methods for temperature control of samples

The invention relates to devices for tempering a liquid bath, in particular for tempering a large number of samples within a reaction container and tempering method.

It is generally known to use temperature control devices in the form of controllable thermostats to set the temperature of samples or materials or to regulate them according to a certain time pattern or to set certain thermal reaction conditions in a sample room. A thermostat usually includes an aquarium bath that is in thermal contact with a heating and cooling device and has a temperature sensor. Depending on the deviation of the temperature value measured with the temperature sensor from a target value, the heating or cooling devices are actuated to heat or cool the water bath. The specific structure of a thermostat depends on the desired application. Recently there have been new requirements for the temperature control of samples or the like in medicine, biochemistry and genetic engineering. m related to the speed, accuracy and reproducibility of the temperature setting, which can no longer be achieved with conventional thermostats.

Examples of biochemical reactions, the course of which requires the setting of defined temperatures in accordance with a specific time pattern, are the polymerase or ligase chain reaction (PCR or LCR processes) for the multiplication of a nuclear acid sequence using certain thermostable enzymes. These PCR processes in particular require the cyclical setting of certain sample temperatures for certain reaction or tempering times. It is generally known to carry out PCR processes in an immersion bath (immersion PCR). The immersion PCR has the disadvantage that temperature gradients occur in the water bath, by means of which the PCR conditions cannot be reproduced sufficiently and can be set precisely.

According to a known technique, a temperature control device has a structure with a reaction vessel, a heating element, a cooling coil and a large number of temperature sensors, as is known, for example, from WO 90/05329. With this temperature-controlled reaction container, a programmable control system enables rapid heating and cooling and the cyclical setting of a temperature profile. However, the basic disadvantages of conventional thermostats are not overcome. These disadvantages manifest themselves in particular in the fact that, in the case of a large volume (approximately 1 to 2 liters) of the reaction vessel, the temperature setting is too slow and too imprecise for numerous biochemical applications and is associated with the setting of a temperature gradient (inhomogeneous temperature control). Furthermore, the reaction vessels are characterized by a high water consumption. If, on the other hand, the volume is reduced in order to achieve shorter setup times, the reaction container and thus the sample throughput become too small for practical applications. Other disadvantages of conventional temperature control devices are high energy consumption, low flexibility and unsatisfactory reproducibility of the temperature transitions (ramp shape between two reaction temperatures, overshoot when setting the temperature).

It is the object of the invention to provide improved devices for tempering a liquid bath, with which the disadvantages of the conventional methods are overcome and which have an expanded range of application. The new devices are intended in particular to provide fast, enable accurate, reproducible and energy-saving temperature settings. The object of the invention is also to provide an improved temperature control method with which the temperature grading can be improved and / or the sample throughput can be increased.

The above-mentioned objects are achieved with devices or methods with features according to patent claims 1, 5, 11 and 19. Advantageous embodiments and uses of the invention result from the dependent claims.

According to a first important aspect of the invention, a nozzle heat exchanger is provided which simultaneously forms a flow for a temperature control medium and a sample holder.

Another important aspect of the invention relates to a reaction container for temperature control of the sample. The reaction vessel comprises a trough and the nozzle heat exchanger and is provided with a flow and a return for connection to a circulating media circulation (for example to the media circuits mentioned above) and is set up inside for a media circulation with reversal of the flow direction. From the flow to the return, the medium is first directed past the samples in a first direction, then deflected in a deflection area and finally directed past the samples in the opposite direction. As a result, the medium that enters the flow with a certain deviation from the target temperature and exits with an opposite deviation at the return after thermal contact with the samples will exert an essentially balanced and homogeneous temperature control effect on the samples. For example, if the sample temperature is too low, medium with an elevated temperature is supplied. The samples near the lead are heated more strongly than the samples at a distance from the lead (e.g. at the steering area), however, when flowing back to the return, the samples are warmed more strongly than the samples at the feed, due to the then still higher media temperature. The balancing effect of the flow principle according to the invention is thus achieved.

According to a further important aspect of the invention, a temperature control method is created in particular, in which the energy-transporting medium is directly connected to two media circuits which are set up to set different temperatures and represent, for example, a heating and a cooling circuit, the temperature in a reaction vessel or a bath or at a sample location by means of optionally operable locking devices and heating or cooling devices in the media circuits. A reaction vessel is an arrangement that can be tempered with the medium and is set up to hold at least one sample. With the locking devices and heating or cooling devices, the medium at the sample location can be adjusted from the circuits as a precisely metered mixture of certain amounts of media with certain temperatures.

The invention also provides a new type of regulation for a temperature control process. The control is aimed at setting a medium, the temperature of which can be adjusted with a heating and a cooling circuit, to a specific target temperature. A total of four controllers are provided for this purpose, which are actuated as a function of the deviation of the sample temperature from the target temperature. They include a main controller that is set up to operate the heating or cooling circuit, a cooling controller that is set up to reduce the sample temperature during the control, a heating control set up to increase the sample temperature during the control, and a pump controller , with which the amount of media passing through a reaction container or a bath or a sample location is set.

A temperature control device according to the invention consists, according to the above-mentioned principle of metering the energy-transporting medium, of adjustable proportions from media circuits of different temperatures, in particular from the reaction vessel mentioned, which is equipped with a flow and a return as part of one of the two media circuits with locking devices and a heating or cooling device, the flow and the return are each connected to the second media circuit via further locking devices. The first media circuit is preferably a heating circuit, which thus leads from the flow via the reaction tank, the return, a pump device, a blocking device and a heating device back to the flow. The second media circuit is then a cooling circuit, which contains a pumping device and a cooling device and can be connected to the forward or return flow via blocking devices. However, the invention is not limited to this design. Rather, a design is also possible in which the first media circuit is the cooling circuit and the second media circuit is the heating circuit.

The temperature control device for implementing such a flow control is preferably designed as a nozzle-type heat exchanger in the reaction vessel, the line system of which simultaneously serves to guide the medium and to hold the sample.

The invention has the following advantages. For the first time, a reaction container with a significantly increased volume (up to 8 1) is created, which temperature-regulates samples in accordance with the requirements in biochemistry, medicine and genetic engineering in terms of accuracy, reproducibility decorability and speed of temperature adjustment met. A high level of energy efficiency, flexibility and speed are achieved when approaching certain temperature holding points. The reaction vessel or heat exchanger according to the invention does not require a lead time due to the device. The tempering process can be started directly without pre-tempering the temperature circuits. Due to the speed of the temperature setting, the temperature of the sample is particularly gentle, since the time during which the sample is close to the desired reaction temperature and the first reactions may already be unreproducible or undesirable is shortened. When certain temperature profiles are run, the samples can remain in the reaction container. Flooding in the temperature setting is avoided. The invention is not restricted to specific applications. It is possible to adapt different types of samples or to use them in other technical areas (e.g. material testing) where rapid temperature changes are important. The device according to the invention can be easily operated and maintained. The invention can be implemented with a wide variety of temperature control media (eg water, 01). As a result, the reaction container according to the invention has an expanded area of application, to which materials adapted to the desired application are used as temperature control media. High temperatures can also be reached without the need for a pressure vessel.

Further advantages and details of the invention will become apparent from the accompanying drawings. Show it:

1 shows a schematic overview of a temperature control device according to the invention, 2 shows a block diagram to illustrate the control according to the invention,

3 shows a flow chart to illustrate a tempering process,

Fig. 4 is a graph to illustrate the

Temperature setting in a tempering process according to FIG. 3, and

Fig. 5 is a schematic perspective view of an inventive nozzle heat exchanger.

According to FIG. 1, a temperature control device according to the invention consists of a reaction container 10 which is part of a heating circuit 20 and is connected to a cooling circuit 30. The reaction container 10 comprises a trough 11, in which a heat exchanger 12 (for details see FIG. 5) with sample receptacles 13 is arranged and which is connected to a fullness measurement 19. The inlet-side connection of the heat exchanger 12 and the outlet-side connection of the trough 11 form the flow 14 and the return 15 of the reaction container 10. Several temperature sensors are provided on the reaction container 10. These include the flow sensor 16, the sample sensor 17 and the return sensor 18. The sensors (or: sensors) are, for example, resistance temperature sensors (eg PT 100), but can also be thermocouples or based on other measuring principles. The flow and return sensors record the media temperature in the flow or return with a distance of approx. 3 to 5 cm from the reaction container 10. The invention is not restricted to the form of the reaction container 10 described here with the heat exchanger 12 inserted, but can also be used with differently designed reaction containers, for example in the form of a flow trough or a closed heat exchanger. exchangers in which the samples do not come into contact with the energy-transmitting medium.

The heating circuit 20 (circulation in the direction of the arrow) comprises the reaction container 10, a dynamic pump 21, a locking device which is formed by the first solenoid valve 22 (MV 2), and a heating device in the form of a continuous-flow heater 23 with a heating temperature limiter 24. The dynamic pump 21 is a circulation pump which is used for the stepless speed setting, eg in the range from 0 to 3000 U / mm. For the operation of the dynamic pump 21, the instantaneous water heater 23 and the first solenoid valve 22, there are em pump regulators 54, heating regulators 55 and cooling regulators 56 (enabling the first solenoid valve 22), the functions of which will be explained with reference to FIG. 2.

The cooling circuit 30 simultaneously has the function of cooling and a buffer reservoir and comprises a static pump 31 which is set up for the permanent circulation of the medium in the cooling circuit 30, a filter 32 (particle filter), at least one buffer store 37 and two refrigeration machines 33a, 33b that act as cooling directions. The cooling circuit 30 also has a branching point between the static pump 31 and the first cooling device 33a, from which there is a connection via the second solenoid valve 35 (MV 1) to a branching point between the instantaneous heater 23 and the flow 14 in the heating circuit. In addition, a further branching point is provided between the second cooling device 33b and the static pump 31 in the cooling circuit 30, from which a connection via a third solenoid valve 36 (MV 2) to the heating circuit 20 at a branching point between the dynamic pump 21 and the first solenoid valve 22 consists. The cow devices 33a, 33b (refrigeration machines) are each equipped with a thermostat 34a, 34b. The thermostats 34a, 34b sense the temperature of the circulating medium with sensors and actuate the cooling devices 33a, 33b to set a predetermined, fixed temperature.

The entire system shown in FIG. 1 is filled with an energy-transporting medium. This medium is preferably water, but can also be formed depending on the application by a suitable salt solution (reduction of lime deposits, improvement of the heat conduction) or by a light oil or a transformer oil. The system is filled z. B. by external filling of the tub 11 with the third solenoid valve 36 open, pumps 21, 31 running and the first and second solenoid valves 22, 35 closed until the buffer tank 37 leaks water at the vent connection, or via a separate feed connection (not shown) .

The performance parameters of the heating and cooling circuits, in particular the volume of the circulating medium and the heating or cooling output of the heating or cooling devices, are selected depending on the application. For the application explained below in the PCR process with a 7.5 1 well 11, for example, the heating circuit 20 for approx. 4.5 1 hot water with a heating capacity of approx. 12 kW and the cooling circuit 30 for approx. 60 1 cooling water (essentially storage or buffer volume of the buffer storage 37) with a cooling capacity of 2 • 1 kW cooling capacity. 1, the cooling devices 33a, 33b can also be replaced by a single cooling device with a correspondingly higher cooling capacity, which, however, can be disadvantageous in terms of energy consumption and operational safety. Fig. 1 also shows an additional ventilation cooler 40, which is provided for the immediate cooling of the instantaneous water heater 23 by taking up surface heat. Any suitable ventilator with sufficient power (for example a control cabinet ventilator) can be used as ventilation device 40.

Finally, FIG. 1 also schematically shows a control device 50 with a sequence control 51, a protection control 52, a main controller 53 (so-called ECO controller), the pump controller 54, the heating controller 55, the cooling controller 56, actuating elements 57 and a display 58. The elements of the control device 50 are explained below with reference to FIG. 2.

An inventive tempering process is carried out by the sequence control 51 and the protection control 52 in cooperation with the controllers 53 to 56 in accordance with the relationships shown in FIG. 2. The sequence controller 51 provides the control signals which represent the specific sequence of a temperature control process. Accordingly, the sequence control 51 has an input 51ι, via the process parameters, such as a sequence of target temperatures T _s , _n , which are to be repeatedly set for N temperature cycles for certain temperature control times t _n , and the sample temperature T _P from the sample probe 17 (see FIG 1) can be entered. At the output 51o, the sequence controller 51 accordingly sends set values x _s to the controller and an off signal to the protective controller 52.

The protection control 52 receives at the input 52ι a series of operationally relevant switching signals, which relate to the state of the unit, the system filling, an emergency shutdown and the like, and the off signal of the sequence control 51. First, with the output 52o of the protection control 52 are the stationary pump 31 of the cooling circuit 30 (see FIG. 1) and second to Receiving an Em signal, the controller main controller 53 and pump controller 54 connected.

The main controller 53 receives the on signal from the protection controller 52 as a release, and the current setpoint x _s and the current sample temperature T _P at the input 53ι. The main controller 53 is set up to switch on the heating or cooling controllers 55, 56 or to assume a zero position as a function of the value of the sample temperature T _P in relation to the target temperature T _s via the output 53o m.

The pump controller 54 receives the on signal from the protection control 52 as a release, and the current setpoint x _s and the current return temperature T _RL at the input 54ι. The pump controller 54 provides a voltage signal (for example in the range from 0 to 10 volts) at the output 54o, which is applied as an input signal to a frequency converter 54a with which the dynamic pump 21 (see FIG. 1) is controlled. If the setpoints and actual values on the pump controller 54 match, the frequency converter 54a sets a predetermined fixed speed on the dynamic pump 21 em depending on the application.

The heating control 55 receives the Em signal from the protection controller 52 as a release, and at the input 55ι em release signal from the main controller 53, the current target size x _s and the current flow temperature T _VL - if in the operating state (protection control 52: Em) with the main controller 53 is actuated by the release signal of the heating controller 55, this gives at the output 55o em voltage signal to a pulse-modulated thyristor controller 55a, with which the water heater 23 (see FIG. 1) is actuated. The output signal of the heating controller 55 can be, for example, a voltage signal in the range from 0 to 10 volts. Depending on the voltage signal, a high pulse rate to achieve a high heating power or a low pulse rate to achieve a low heating power is generated. If the target and actual values on heating controller 55 match, heating controller 55 interrupts its own output signal via an internal switch (opener).

The cooling controller 56 in turn receives the Em signal from the protection controller 52 as a release, and at the input 56ι the release signal from the main controller 53, the current target size x _s and the return sensor 18 (see FIG. 1) the current return temperature T _RL . At the outlet 56o of the cooling controller 56 there is a connection to the ventilation device 40 (see FIG. 1) and a connection to the solenoid valves 22, 35 and 36. In the event of small deviations between the setpoint and actual values of, for example, 0.5 to 1 °, only the ventilation device is switched on as cooling. The solenoid valves are actuated at higher temperature differences between the setpoint and actual values, as will be explained in detail below.

2 also shows the display device 58, which is set up to display the number of cycles N, the current setpoint value Xs and / or the current sample temperature T _P and for this purpose with the sequence control 51 and the sample sensor 17 (or the corresponding input of the main controller 53) connected is. The actuating elements 57 of the control device 50 (see FIG. 1) are correspondingly represented in FIG. 2 by the circuit 57 and illustrate conventional switches as are provided on the temperature control device and in particular a main switch “Em / Aus” and an emergency stop switch include. When the actuating elements 57 are released, the cooling mechanisms 33a, 33b are also switched on.

In the following the sequence of temperature control is explained with a device according to the invention according to FIGS. 1 and 2. In a preparation step, the device is first brought into an operational state by filling the reaction container 10 and the circuits 20, 30 and specifying the temperature setpoints T _s , _n , the tempering times t _n and the number of cycles N on the sequence controller 51. The pump 31 is activated so that the water circulates in the cooling circuit 30. After querying all the safety conditions via the actuation elements 57 or the protective control 52 (no excess temperature, no water shortage, cover of the reaction container locked) and actuation of a start button (actuation elements 57), the water temperature in the cooling circuit 30 is initially set to 20 ° C. As soon as this starting value given here by way of example is reached, the actual temperature control process is started and the pump 21 is started. The temperature in the water bath of the reaction vessel in which the samples are located is set according to a specific, application-dependent, time-based temperature program (example see below). After the end of the program, the device is switched back to a state ready for operation.

The above-mentioned controllers work together as follows to control the temperature during the program run. All controllers are designed as proportional controllers and are set up to process the same current setpoint x _s , which corresponds to one of the setpoint temperatures T _{S n} . The current setpoint is compared at the main controller 53 with the sample temperature from the sample sensor 17, at the pump controller 54 with the return temperature from the return sensor 18, at the heating controller 55 with the flow temperature from the forward sensor 16 and finally at the cooling controller 56 again with the return temperature.

If the sample temperature is below the target temperature (heating), the main controller 53, which is the first in the controller hierarchy, issues the release signal to the heating controller 55. The cooling controller not released remains in the state of

Ready for operation, with the target / actual value comparison being carried out continuously. In the case of heating, the output signal (for example in the range from 0 to 10 volts DC voltage) of the heating controller 55 is now applied to the pulse-modulated thyristor controller 55a, which accordingly controls the water heater 23. If the setpoint / actual value deviation (x _w ) increases, a high pulse rate and thus a high heating output is set, and if the deviation x decreases, a small pulse rate or a small heating output is set. If x disappears, the output signal of heating controller 55 is switched off internally. If the sample temperature is above the setpoint temperature (cooling case), the release signal is sent from the main controller 53 to the cooling controller 56, the heating controller 55 now remaining in the ready-for-operation state (continuous setpoint / actual value comparison). In the case of cooling, the cooling controller 56 switches the ventilation device 40 em with a small deviation x _w (<0.5 to 1 ° C.). In the event of a larger deviation x _w , the second and third solenoid valves 35, 36 are released and the first solenoid valve 22 is closed. The release of the second and third solenoid valves 35, 36 is in turn dependent on the magnitude of the deviation x by means of corresponding release or cycle times, which advantageously ensures that the controller is particularly continuous.

If the flow temperature is the same as the return temperature, the temperature of the samples has stabilized. By comparing the flow and return temperatures, a signal for the temperature control can be derived.

In addition to the heating or cooling mentioned, the pump controller 54 runs independently in parallel. Depending on the rule (heating or cooling), the speed of the dynamic pump 21 (see FIG. 1) is set according to the following scheme. in the In the case of heating, small deviations x (example: 0.5 ° C) become a high speed and with large deviations x _w (example: 5 ° C) a low speed and in cooling cases with small deviations x _w a low speed and with large deviations x _w a high speed of the pump 21 set. If the deviation x _w disappears, the dynamic pump 21 runs at a predetermined fixed speed (for example 3000 U / mm). At this fixed speed, the flow rate through the pump is z. B. 25 1 / mm.

During operation, the device according to the invention is continuously monitored via a safety control chain with regard to excess media temperature, lack of water and the cover locking. If critical operating states occur, the device switches off automatically. A new start only takes place after the start button has been pressed manually. The level in the reaction container 10 is regulated according to the following principle.

The fill level in the reaction container 10 is measured with a fill level measuring device 19 (see FIG. 1), which comprises a float switch device (eg with two switches). The float switch device is connected to the solenoid valves 22, 35 and 36. In the case of heating or cooling, an impermissibly high fill level is reduced by temporarily opening the third solenoid valve 36 with the second solenoid valve 35 and the first solenoid valve 22 closed. Feeding takes place by temporarily opening the second solenoid valve 35 with the third solenoid valve 36 closed and the first solenoid valve 22 open.

In order to avoid malfunctions of the full-level measuring device 19 due to wave-shaped full-level fluctuations in the reaction container 10 by pulsed actuation of the respective locking devices (solenoid valves), the full-level measuring device is 19 is preferably designed as a vessel communicating with the reaction container 10. The float switch is located in the additional vessel, which is separated from the actual reaction container by a connection line or a partition with an opening (shown). As a result of this provision, wave shearings in the reaction vessel in the additional vessel will only occur weakly, so that the fullness measurement can be carried out without errors.

The control according to FIG. 2 can be equipped with electrical filters for the temperature sensors to smooth the control behavior. The electrical filters are set up to round off or cut off the 1/100 degree position of the temperature signals from the sensors.

In the following, an application of the temperature control according to the invention, as occurs in the PCR process, is explained by way of example with reference to FIG. 3. The aim of temperature control is to cyclically repeat three different temperature setpoints. After reaching the respective target value, the temperature should be kept constant for a predetermined time t. The setting of the three temperatures forms a cycle. This cycle should be repeated as often as required, depending on the application. In the PCR reaction, the target temperatures are, for example, T _s , ι = 95 ° C, T _s , ι = 65 ° C and T _s , ₃ = 72 ° C. The tempering times t should each be, for example, 1 minute, with the tempering time ti of the first target temperature Ts, ι being 4 minutes in the first heating cycle in order to achieve the greatest possible DNA denaturation at the initially low DNA concentration. In addition, the parting times (transition times between the target temperatures) should be in the minute range (approx. 2 to 3 minutes). After loading the sample receptacles 13 (see FIG. 1), as will be explained in detail below with reference to FIG. 5, in the inventive temperature control process according to FIG. 3, after the start 300, a query is first carried out to determine whether the start conditions have been met (step 301 ). This includes, in particular, the question of whether the emergency stop switch is triggered or the stop button is pressed, whether the fill level in the reaction container corresponds to predetermined values, whether the lid is locked, whether there is an excess temperature and whether the desired setpoints T _S ι to T _{S) 3} and the number of cycles and the tempering times are entered. The sequence control 51 (see FIG. 2) then passes the first setpoint T _s, ι = 95 ° C. to the controller at step 302, at which the setpoint / actual comparison 303 is carried out and heating or cooling is triggered becomes. As soon as the target temperature is reached, the cycle number is queried (step 304) in order to set the sequencer 51 a timer circuit according to the example above to 4 mm (for the first cycle) or to 1 mm (for each subsequent cycle). At step 304, the time ti set in the timer circuit is queried and, as long as the time is running, the target / actual comparison 303 is repeated continuously.

When the temperature control time ti has elapsed (query at step 305), the sequence control 51 inputs the second set temperature T _{S) 2} = 65 ° C. (step 306). The following steps target-actual comparison (307) and query of the timer circuit (308) take place analogously to the regulation of the first target temperature, whereby the cycle number is not differentiated here. During the second phase (T _Sr2 ) the DNA denatured in the first step is increased. At the third reaction temperature (T _s , ₃ ) the amplified DNA is assembled into a new strand. For this purpose, steps 309 to 311 with steps 306 to 308 essentially become repeated. After the third tempering period, the

Number of cycles N is decremented and queried whether the current number of cycles N * is equal to zero (step 312). If N * is not equal to zero, there is a return to step 302 (input of the first target temperature). Otherwise, the program is stopped (step 313).

The number of cycles is freely selectable depending on the application and can be approx. 40 to 50. 4 shows an example of the time course of the sample temperature for a total of three cycles. Each setting process m in relation to a target temperature comprises a setting time for setting the target temperature (according to steps 303, 307 and 310 in FIG. 3) and the actual tempering time t. The exposure time is particularly dependent on the medium, the media volumes for heating or cooling and the thermal load (sample quantity). Curves A and B accordingly show the water temperature and the sample temperature, the course of which compared to the water temperature is delayed due to the delay in establishing the thermal equilibrium. 4 shows a decisive advantage of the invention in relation to the speed and consistency of the setting of the media temperature.

Details of the reaction container 10 (see FIG. 1) are explained below with reference to FIG. 5. It is emphasized that the design of the heat exchanger as a sample holder is an independent aspect of the invention, which is preferably implemented in combination with the control principle explained above, but can also be used independently thereof for sample temperature setting using conventional thermostats. 5 shows the reaction container 10 with the trough 11 and the sample holder functioning as a heat exchanger 12, the front wall of the trough 11 not being shown for reasons of clarity.

The trough 11 has the shape of a vessel known per se from laboratory applications, the inner shape of which is preferably adapted to the outer shape of the heat exchanger 12. If the heat exchanger 12 is arranged in the trough 11 with as little play as possible, this has an advantageous effect on the speed and accuracy of the temperature setting. The water flowing back from the nozzles (see below) to the outlet is forced into the immediate vicinity of the samples to be tempered. In the example shown, the tub 11 has a rectangular plan. On a side wall corresponding to the narrow tub side, the return 15 is provided as a connecting attachment between the tub interior and the pipe connection to the heating circuit 20 (see FIG. 1). On the upper edge of the side walls of the tub 11, a peripheral support 111 is attached as a support for a lid (not shown). The resting or locking of the lid can be detected by a sensor and taken into account in the protective control 52 (see FIG. 2). The heat exchanger 12 is surrounded by a sheathing 112, which provides electrical engineering support and thermal insulation from the environment and consists, for example, of neoprene. The tub volume is in the range of 5 to 8 1 (e.g. 7.5 1) with a floor area of approx. 135 mm • 460 mm at a height of 120 mm. The invention is not limited to realizing these large proportions.

The heat exchanger 12 (nozzle heat exchanger) serves simultaneously as a sample holder or support frame for the samples to be tempered. Accordingly, the design of the heat exchanger 12 is adapted to the sample format, depending on the application. an adaptation to the format of microtiter plates is preferred for biochemical and genetic engineering applications (here a microtiter plate is referred to as a sample). The heat exchanger 12 consists of the frame 121, a distributor 122, an inlet connection 123 and outlet nozzles 124.

The frame 121 consists at least partially of components, the inner media lines in the form of channels, cavities, shafts or the like. contain. The components are arranged in such a way that receptacles 13 for the samples (eg microtiter plates) are formed, the internal media lines being guided in such a way that good thermal contact between the medium penetrating the components and the samples in the receptacles is ensured. In the illustrated exemplary embodiment, the frame 121 is in the form of a shelf with horizontally aligned in the operating state the bottom 125 and to vertically aligned supporting elements 126. Thus, a matrix array of 7 ^• 5 receptacles for the samples corresponding to m seven levels and five stacks (IV) is provided. With a 16 ^• 24 format of the microtiter plates used, a total of 13 440 individual samples can be subjected to a temperature control process simultaneously.

According to a preferred embodiment of the invention, the sample temperature sensor 17 (see FIG. 1) or generally at least one temperature sensor of a sample holder is arranged in a shape that corresponds as closely as possible to the sample shape. It is envisaged, for example, to use a Fuhler microtiter plate in one of the receptacles, which contains no substances, but only the temperature sensor. In this case, 34 samples are taken from the reaction container 10. This attachment of the sample probe is not a mandatory feature of the invention. It can also be placed elsewhere in the sample container or even omitted entirely (see below). The bottoms 125 are hollow elements which form at least one shaft-shaped, flat media line from the distributor 122 to the discharge nozzles 124 on each level. This ensures a uniform temperature control of the floor and thus of the samples lying on the floor in the recordings. According to a preferred embodiment of the invention, several, strip-shaped hollow elements are provided in each floor 125, which run in the plane of the respective floor over the entire width from the distributor 122 to the outlet nozzles 124. The structure according to the invention is implemented, for example, with six waveguide strips, but fewer strips can also be provided. Each waveguide strip has a rectangular cross section with typical dimensions of, for example, 10 • 3 mm ² . The broad side of the waveguide strips lies in the plane of the bottom 125.

In the operating state, the flow 14 (see FIG. 1) is attached to the coupling element 127 of the inlet connection 123. The coupling element 127 is preferably a detachable quick coupling which enables the heat exchanger 12 to be removed from the trough 11 without further changes to the overall system. The inlet connection 123 consists of a flexible hose. The medium used for temperature control (eg water) runs from the feed 17 through the inlet connection 123 to the distributor 122, where it is distributed to the floor of the individual levels of the frame 121. From the distributor 122, which is located on the narrow side of the frame, the medium flows longitudinally through the bottom of the stack I in the direction of the stack V. At the ends of the frame 121 opposite the distributor 122, the outlet nozzles 124 are provided at the ends of the bottom which the medium flows through the tub 11. Since the shape of the heat exchanger 12 is adapted to the shape of the trough 11, the outlet nozzles 124 are located in the immediate vicinity of a side wall of the trough 11. The medium emerging at the end of the heat exchanger 12 opposite the distributor 122 can be freely m the tub 11 flows, but experiences essentially a reversal of the flow direction due to the adjacent tub wall. The outlet nozzles 124 thus form a deflection area with the adjoining tub wall, from which the medium flows back through the tub 11 through the frame 121 over its surface and the samples along the stacks V to I hm to the return 15. The backflow therefore does not take place inside the hollow components of the frame 121, but rather outside of them, so that the samples are wound directly by the medium in the sample receptacles.

The regular structure of the sample holder ensures a homogeneous and uniform flow through the sample container 10 corresponding to two flow sections. In the first flow section there is an essentially laminar flow through the floor from the distributor 122 hm to the outlet nozzles 124. In the second flow section there is also a homogeneous, almost laminar backflow from the deflection area (outlet nozzles 124) hm to the return 15. A particular advantage of the invention is that that the lambda of the flow enables an extremely even heat distribution from the medium to the samples. For example, in the case of heating, the medium first flows from the inlet connection 123, heating the samples lying in the receptacles on the bottom 125 with a continuously falling temperature through the bottom to the outlet nozzles 124. The backflow under the action of the dynamic pump 21 essentially takes place above the samples m the recordings. Heat exchange is again effected, with the samples (stack I) heated more strongly in the first flow section being heated relatively less and the samples heated less in the first flow section (eg stack V) being heated more strongly. Thus, the first samples on the outlet side are subjected to the highest temperature from their underside and the lowest temperature from their top, whereas samples in the vicinity of the outlet nozzles 124 are exposed from the top and bottom be subjected to substantially similar temperatures. With this flow principle, all samples are supplied with the same total energy.

The described reaction container according to FIG. 5 is used in such a way that first the frame 121 is loaded with the samples (microtiter plates). Subsequently, on the coupling element 127, the connection of the flow 14, the insertion of the heat exchanger 12 m, the tub 11 and the covering and filling of the system (see above). With the dynamic pump 21, the medium, after it has filled the distributor 122, is pressed into the bottom 125 and through the outlet nozzles 124 into the trough, and is sucked out of the trough into the rest of the media circuit due to the differential pressure between supply and return via the return 15 .

After carrying out the temperature control process, as described above, for example, the sample holder (heat exchanger 12) is removed from the tub, and after the coupling element has been released, all of the samples can be transported as a block to the site for further processing.

Parts of the level measurement device 19 (see FIG. 1) are not shown in FIG. 5.

The invention is not limited to the described embodiments of the control method or the temperature control device, but rather can be modified depending on the application. For example, it is possible to reduce the number of temperature sensors on the reaction vessel. If the temperature control takes place under reduced accuracy requirements, the sample probe can be omitted and the regulation principle can be adapted in such a way that heating or cooling is effected until the temperatures at the flow and return are equal. This condition corresponds to that desired equilibrium, in which the sample temperature inevitably corresponds to the flow and return temperatures. Furthermore, the valves shown can be replaced by other locking devices, for example by three-way valves, in particular if there are reduced demands on the speed of the temperature setting. Other possible modifications relate to the number and type of heater or cooler, the size of the heat exchanger, the shape of the reaction vessel, the type of level measurement and the use of the ventilation device.

Claims

PATENT CLAIMS

1. Heat exchanger for tempering a large number of samples in a liquid bath, characterized in that the heat exchanger (12) forms a sample holder and an inlet connection (123), a distributor (122), em frame (121) with receptacles for the samples and outlet nozzles (124), the frame (121) forming a throughflow for a medium from the inlet connection (123) via the distributor (122) and the frame (121) hm to the outlet nozzles (124).

2. The heat exchanger as claimed in claim 1, in which the frame (121) has the form of a shelf with a floor (125) which is horizontally oriented in the operating state and support elements (126) which are oriented perpendicularly thereto, the floor (125) being hollow elements which are in each plane form a shaft-shaped, flat media line from the distributor (122) to the outlet nozzles (124).

3. Heat exchanger according to one of claims 1 or 2, wherein the heat exchanger (12) is designed as a support frame for microtiter plates.

4. Heat exchanger according to one of claims 1 to 3 in which at least one sample holder of the frame (121) has a temperature sensor.

5. reaction container for tempering a large number of samples in a liquid bath, consisting of a trough (11) and a heat exchanger (12) according to one of claims 1 to 4.

6. reaction container according to claim 5, wherein the trough (11) is a vessel with an inner shape which is adapted to the outer shape of the heat exchanger (12), and on a side wall a connecting lug between the inside of the tub and a pipe connection with a media circuit Owns 20.

7. Reaction container according to claim 6, in which the heat exchanger (12) is arranged in the trough (11) in such a way that the outlet nozzles (124) are located on the trough end opposite the connecting attachment.

8. Reaction container according to claim 7, in which the outlet nozzles (124) form a deflection area with the adjoining tub wall, which is set up for deflecting the medium from the outlet nozzles (124) to the connection attachment of the tub (11).

9. Reaction container according to one of claims 5 to 8, in which the heat exchanger (12) is inserted into and removed from the trough (11).

10. Reaction container according to one of claims 5 to 9, which communicates via a line or a partition with a passage opening with a full-level measuring device (19).

11. A method for tempering a liquid bath in a reaction vessel (10) according to any one of claims 5 to 9 with a medium, the temperature of which with a heating circuit and a cooling circuit (30) can be set, each having heating or cooling devices (23, 33a, 33b), the medium flowing through the reaction vessel (10) from a flow (14) to a return (15) and from the return (15 ) depending on the actuation of locking devices (22, 35, 36) through the heating and / or cooling circuit (20, 30) to the flow (14), the heating or cooling devices (23, 33a, 33b) and the locking devices (22, 35, 36) are actuated so that the medium in the reaction vessel has a predetermined target temperature.

12. The method according to claim 11, wherein the current temperature of the medium is measured in the reaction vessel (10) and, if the current temperature is lower or higher than the predetermined target temperature, with a main controller (53) in each case corresponding to the heating control (55) or em cooling controller

(56) is actuated, which set the locking devices and heating or cooling devices of the heating and cooling circuits (20, 30) such that the medium enters the reaction vessel (10) with a higher or lower temperature at the flow (14) m .

13. The method according to claim 12, wherein with the heating regulator (55) the heating power of the heating device (23) in the heating circuit (20) and with the cooling controller (56) the locking devices

(35, 36) are actuated, via which the cooling circuit (30) is connected to the heating circuit (20), so that a predetermined portion of the medium is passed through the cooling circuit (30).

14. The method according to claim 12, wherein the flow temperature of the medium at the flow (14) and the return temperature of the medium at the return (15) are measured and the heating control

(55) m as a function of the deviation of the return temperature from the predetermined target temperature and the cooling controller (56) depending on the deviation of the flow temperature from the predetermined target temperature.

15. The method according to any one of claims 11 to 14, wherein the medium forms the liquid bath and is pumped with a dynamic pump (21) through the reaction container (10).

16. The method according to claim 15, wherein the performance of the dynamic pump (21) with a pump controller (54) is set depending on the return temperature of the medium at the return (15).

17. The method according to any one of claims 11 to 16, wherein the heating device (23) in the heating circuit (20) is a continuous flow heater and is cooled with a Ventilationsemπchtung (40) in the event of small control deviations of the current temperature.

18. The method according to any one of claims 11 to 17, in which a full level measurement takes place in the reaction container (10) and the locking devices (22, 35, 36) are actuated as a function of the fill level and the control state in order to maintain a predetermined fill level in the reaction container (10). adjust.

19. Temperature control device for a liquid bath in a reaction vessel (10) according to one of claims 5 to 10, which can be tempered with two media circuits (20, 30) of different temperatures, each having heating or cooling devices (23, 33a, 33b), wherein the reaction vessel (10) has a flow (14) and a return (15) and is part of one of the media circuits and via locking devices

(35, 36) can either be connected to or disconnected from the other media circuit.

20. Temperature control device according to claim 19, wherein the media circuits comprise a heating circuit (20) and a cooling circuit (30) and the reaction vessel (10) is part of the heating circuit (20).

21. Temperature control device according to claim 20, wherein the heating circuit (20) from the flow (14) via the reaction vessel

(10), the return (15), a dynamic pump (21), a first locking device (22), the heating device (23) hm leads to the flow (14).

22. Temperature control device according to claim 20, wherein the cooling circuit (30) comprises a static pump (31) and at least one cooling device (33a, 33b) and via second and third blocking devices (35, 36) with the flow (14) or return (15) of the reaction container (10) is connected.

23. Temperature control device according to one of claims 19 to

22, in which a controller control (50) is provided, which has a main controller (53) for setting the heating or cooling circuit (20, 30), a heating and a cooling controller (50, 56) for setting the heating circuit (20 ) or the cooling circuit (30) and a pump controller (54) for adjusting the circulation of the medium in the heating circuit and / or in the cooling circuit (30).

24. Temperature control device according to one of claims 19 to

23, in which the water heater (23) in the heating circuit (20) is equipped with a ventilation device (40).

25. Temperature control device according to one of claims 19 to

24, in which the reaction container (10) has a full level measuring device (19).

26. Temperature control device according to one of claims 19 to 25, in which a heat exchanger according to one of claims 1 to 4 is provided as the Dusenstock heat exchanger.

27. Use of a heat exchanger, a reaction vessel, a method or a temperature control device according to one of the preceding claims for providing predetermined temperature conditions in biochemical or genetic engineering reactions.