PIPETTING DEVICE WITH FUNCTIONAL CHECKING AND METHOD FOR FUNCTIONAL CHECKING OF A PIPETTING DEVICE

Abstract

The invention relates to methods and to pipetting apparatuses for detecting at least one performance state of the suction mechanism of a pipetting device used for pipetting. Such a method and such a pipetting apparatus each use an electronic control device, a suction mechanism which, amongst other things, has an electrically powered motor, a measurement device have a pressure sensor or a measurement device acquiring the motor current for characterizing the physical work which is performed by the suction mechanism, wherein the pipetting device can partly be provided with a resistance device by means of which, during the execution of the method, the mechanical, in particular the hydraulic, resistance of the suction mechanism against the physical work performed by the motor is increased, wherein the control device is configured to detect a performance state of the pipetting apparatus, to acquire at least one value of this measurement value in function of a defined movement of the piston element, to store the at least one value of this measurement value in the data storage device.

Claims

1. Method (200) for detecting at least one performance state of the pipetting suction mechanism of a pipetting apparatus (1, 1, 1a, 1b), in particular a pipette or a repeater pipette, wherein the suction mechanism comprises an electrically powered motor (14), a piston chamber (18), and a piston element (12) arranged movably therein and driven by the motor, and by the movement of which the suction of a fluid can be effectuated by the formation of a fluid flow through an open suction channel (19) of the piston chamber, with the pipetting apparatus being configured to acquire the motor current drawn by the motor as measurement value for the characterization of the physical work that is performed by the suction mechanism for the electrically powered movement of said piston element, and with the method comprising the following steps, which can be carried out by a data-processing control device (15) of the pipetting apparatus: a) acquiring at least one value of this measurement value in dependence on a defined movement of the piston element; (201) b) comparing the at least one measurement value with at least one reference value. (202)

2. Method (200) for detecting at least one performance state of a pipetting suction mechanism of a pipetting apparatus (1, 1, 1a, 1b), in particular a pipette or a repeater pipette, wherein the suction mechanism comprises an electrically powered motor (14), a piston chamber (18), and a piston element (12) arranged movably therein and driven by the motor, and by the movement of which the suction of a fluid can be effectuated by the formation of a fluid flow through an open suction channel (19) of the piston chamber, with the pipetting apparatus comprising a resistance device (20), by means of which the mechanical, in particular the hydraulic resistance of the suction mechanism against the physical work performed by the motor is increased during the execution of the method, and with the pipetting apparatus comprising a pressure sensor (16b) that measures the pressure in the piston chamber, and being configured to acquire the pressure measured by the pressure sensor for the characterization of the physical work that is performed by the suction mechanism for the electrically powered movement of that piston element, and with the method comprising the following steps that can be executed by a data-processing control device of the pipetting apparatus: a) acquiring at least one value of this measurement value in dependence on a defined movement of the piston element; (201) b) comparing the at least on measurement value with at least one reference value. (202)

3. Method according to claim 1 or 2, wherein step a) is executed at a moment before a pipetting process that is started by the user and executed with the pipetting apparatus, in particular executed immediately before the start of said pipetting process.

4. Method according to claim 1 or 2, wherein step a) is executed during a movement of the piston element that serves exclusively for the detection of at least one performance state.

5. Method according to claim 4, wherein step a) is executed automatically, and controlled by the control device of the pipetting apparatus, by the execution of a functional checking program.

6. Method according to claim 1, wherein the pipetting apparatus is equipped with a resistance device (20), by means of which the mechanical, in particular the hydraulic resistance of the suction mechanism against the physical work performed by the motor is increased during the execution of the method.

7. Method according to claim 2 or 6, wherein the resistance device is a closure element (20), with which the suction channel (19) is blocked partially or closed completely.

8. Method according to claim 7, wherein the closure element is a closure cap (20).

9. Method according to one of the preceding claims, wherein a number N of values of the measurement value is measured during the movement of the piston element in step a) and stored in a step c), with the measurement and the storing taking place in particular in alternation.

10. Method according to one of the preceding claims, wherein the motor is a DC motor (14) that makes available the information on the drawn motor current via an electrical contact.

11. Method according to one of the claims 1 through 10, comprising the step: c) storing this at least one value of this measurement value in a data storage device (15a) of the pipetting apparatus. (203)

12. Pipetting apparatus (1; 1; 1a), in particular a pipette or a repeater pipette for pipetting fluid samples in a laboratory, comprising a suction mechanism that comprises an electrically powered motor (14), a piston chamber (18), and a piston element (12) arranged movably therein and driven by the motor, and by the movement of which the suction of a fluid can be effectuated by the formation of a fluid flow through an open suction channel (19) of the piston chamber, a data-processing control device (15) that comprises at least one data storage device (15a), a measurement device (16a) for the acquisition of the motor current drawn by the motor as a measurement value for the characterization of the physical work that is performed by the suction mechanism for the electrically powered movement of that piston element, and wherein the control device is configured to detect a performance state of the pipetting apparatus, a) to acquire at least one value of this measurement value in function of a defined movement of the piston element, b) to compare the at least one value of the measurement value with at least one reference value. c) optionally: to store the at least one value of this measurement value in the data storage device.

13. Pipetting apparatus according to claim 12 that is equipped with a resistance device (20), by means of which the mechanical, in particular the hydraulic resistance of the suction mechanism against the physical work performed by the motor is increased during the execution of the method.

14. System of a pipetting apparatus according to claim 12 and a resistance device, by means of which the mechanical, in particular the hydraulic resistance of the suction mechanism against the physical work performed by the motor can be increased during the execution of the method.

15. Pipetting apparatus (1; 1; 1b), in particular a pipette or a repeater pipette for pipetting fluid samples in a laboratory, comprising a suction mechanism that comprises an electrically powered motor (14), a piston chamber (18), and a piston element (12) arranged movably therein and driven by the motor, and by the movement of which the suction of a fluid can be effectuated by the formation of a fluid flow through an open suction channel (19) of the piston chamber, a data-processing control device (15) that comprises at least one data storage device (15a), a measurement device comprising a pressure sensor (16b) for the acquisition of the pressure applied in the piston chamber as a measurement value for characterizing the physical work that is performed by the suction mechanism for the electrically powered movement of this piston element, wherein the pipetting apparatus is equipped with a resistance device (20), by means of which during the execution of the method the mechanical, in particular the hydraulic resistance of the suction mechanism against to the physical work performed by the motor is increased, wherein the control device is configured to detect a performance state of the pipetting apparatus, a) to acquire at least one value of this measurement value in function of a defined movement of the piston element, b) to compare the at least one value of the measurement value with at least one reference value. c) optionally: to store the at least one value of this measurement value in the data storage device.

16. Program code for the implementation of the method according to claim 1 or 2 in a pipetting apparatus that can be executed by a data-processing control device of the pipetting apparatus such that this pipetting apparatus is a pipetting apparatus with the features according to one of the claims 12 through 15 or such that the method according to claim 1 or 2 can be executed by it.

Description

[0107] In the figures:

[0108] FIG. 1a depicts a perspective lateral view of the pipetting apparatus according to the present invention that is provided as an air-cushion pipette, with its nose cone being connected to a pipette tip.

[0109] FIG. 1b depicts a lateral view of a pipetting apparatus according to the present invention that is provided as a repeater pipette in a preferred embodiment, with a dispenser syringe being attached to it.

[0110] FIG. 2a depicts a first preferred embodiment of the pipetting apparatus according to the present invention, in which the motor current is used as a measurement value to evaluate the performance state of the suction mechanism.

[0111] FIG. 2b depicts a second preferred embodiment of the pipetting apparatus according to the present invention with a closure element, in which the pressure in the piston chamber is used for evaluating the performance state of the suction mechanism.

[0112] FIG. 2c depicts a closure element that can be used in a functional checking.

[0113] FIG. 3a depicts a series of positions of the piston element that can be used in a measurement of a reference curve of measurement values and in a functional checking according to the method according to the present invention.

[0114] FIG. 3b depicts a curve of reference values + with a tolerance range and measurement values o and x of two possible functional checkings carried out according to the method according to the present invention on the pipetting apparatuses from FIG. 1a, 1 b, 2a, 2b.

[0115] FIG. 4 depicts schematically the process of the method according to the present invention according to an embodiment.

[0116] FIG. 5a depicts a series of positions of the piston element that can be used in a measurement of a reference curve of measurement values and in a different functional checking according to the method according to the present invention.

[0117] FIG. 5b depicts a curve of reference values + with a tolerance range and measurement values o and x of two possible functional checkings carried out according to the method according to the present invention on the pipetting apparatuses from FIG. 1a, 1 b, 2a, 2b.

[0118] FIG. 1a depicts a perspective lateral view of a pipetting apparatus 1 according to the present invention, which is provided as an electronic air cushion pipette 1 and with a pipette tip 11 being connected to the nose cone 11a. The air cushion pipette comprises an integrated piston (not visible, inside the housing 2) that can create a vacuum inside the pipette tip when the piston element in the piston chamber is moved upwards by the electric motor. By this, the sample to be pipetted is sucked into the pipette tip, and the sample is dispensed from the pipette tip by an overpressure in the piston chamber. The typical maximum capacity of such air cushion pipettes are 100 nanoliter to 10 milliliter. The air cushion pipette 1 comprises a user interface device, in particular a dial 3a, a display 3, a control rocker switch 4. With the dial 3a, the operational modes of the pipetting apparatus can be selected. One of these operational modes functional checking is used to carry out the method according to the present invention resp. for the selection of a display page for selecting at least one method for functional checking, defined by, if applicable, one or more operational parameters. With the ejection button 3b, the pipette tip can be ejected. The air cushion pipette 1 comprises furthermore an electrical control device and a measurement device for measuring the measurement value (each not visible). FIG. 1b depicts a pipetting apparatus 1 according to the present invention designed as a repeater pipette 1 according to a preferred embodiment, to which a dispensing syringe 11 is connected. The pipetting apparatus comprises a user interface device that comprises a display 3, which serves in particular to display the values of operational parameters of the pipetting apparatus and serves in particular to describe the operational parameters. By means of a dial 3a, the operational mode of the dispenser is selected. In an operational mode, a preferred automated dispensing process is defined by means of a set of operational parameters or can be defined by the user by setting or selecting the values of these operational parameters. The user interface device comprises furthermore a control rocker switch 4 as a control element that comprises an upper and a lower pivoting range. With this control rocker switch, the user navigates through selection menus of the graphical user interface, by means of which the control device queries at least one operational parameter. In the dispensing mode of the pipetting apparatus, the uptake of a fluid volume occurs by suction from an initial container (not shown) into the reservoir of the dispenser syringe by a first actuation of the trigger button 4a, all subsequent actuations of the trigger button 4a each trigger a dispensing step. The operational parameters used for aspirating or dispensing the sample relate in particular to the sample volume to be aspirated and the uptake rate to be used (volume per time) orequivalently in the case of a known container geometrythe time span to be used for the aspiration. These operational parameters used in the definition of pipetting processes can also be used in a similar way in the definition of a functional checking. The container geometry resp. the container type can be read out automatically in particular via a code in the transport container by the pipetting apparatus by means of a preferably provided reading device. When moving the sample by means of the dispenser syringe 11, the positive displacement principle is used, as described above.

[0119] The piston 13 with the piston element 14 of the dispenser syringe 11 comprises an outwardly exposed connection attachment 15 that can be connected to a spindle 12 of the pipetting apparatusand can be detached from it again. The trigger button 4a starts in particular a dispensing process, in which the fluid sample contained in the transport container 11 is dispensed according to predetermined operational parameters. These operational parameters determine in particular the number of dispensing steps, the dispensing volume of a dispensing step, and the dispensing rate (volume per time), resp. a value proportional thereto, to be met during one dispensing step or multiple or every dispensing steps. The pipetting apparatus 1 is in particular program-controlled, i.e. the various sets of operational parameters that are each assigned to a pipetting program and therefore to a specific operational mode, can be defined in a program-controlled manner, so that a user selects, if applicable, the desired pipetting program for the execution of the desired pipetting process, and, if desired, sets at least one operational parameter.

[0120] The dispenser syringe 11 comprises a reservoir with a larger diameter d2 and comprises an opening with a smaller diameter d1, d1<d2. The small opening d1 accounts for most of the flow resistance generated by the dispensing syringe 11 during pipetting. The smaller diameter therefore defines a predetermined resistance that, when pipetting a certain volume at a certain pipetting speed, requires a motor power that corresponds to the reference data in the normal case resp. a behavior according to a reference curve of the measurement value, in particular the motor current. The pipetting apparatus measures the values for the measurement value in step a), compares them in step b) with the reference data and, optionally, stores them in a step c) in a non-volatile data memory. In the case of a deviation, which is generally characterized by leaving a tolerance range in the development of the measurement value or at least one tolerance value for the at least one measurement value, the user is informed and/or the result is stored in the data storage device.

[0121] As depicted in FIG. 2a, the pipetting apparatus 1 comprises in a first preferred embodiment among others the following components: a user interface 13 in conjunction with the electrical data processing control device 15, with which a pipetting process can be controlled electrically, a piston element 12 on a piston rod 12a, by the movement of which in the piston chamber 18 the fluid sample can be pipetted through the suction channel 19, which ends in an opening in the basal side of the nose cone 11a, a motor device 14 that can be addressed electrically by the control device 15, with which the movement of the piston element can be driven via the transmission 17.

[0122] A measurement device comprising a rotational speed sensor 16a is, in the present case, a component of the electronic control device of the motor device 14, here a DC motor 14, and can be considered as a component of the electrical control device 15, with which the measurement device 16a is signal-connected. The measurement device 16a includes a current sensor.

[0123] The motor rotates stepwise in the smallest increments a rotor device (not shown), which in turn moves stepwise a spindle of the transmission 17, the rotation of which causes the stepwise translational movement of the piston 12a along the direction A (FIG. 1c), which in this way effectuates the uptake and dispensing of the sample in the transport container resp. out of it.

[0124] The pipetting apparatus 1b in FIG. 2b is built similarly to the pipetting apparatus 1a in FIG. 2a, as can be recognized by the same reference numerals. The measurement device 16b integrated into the pipetting apparatus comprises a pressure sensor that measures the pressure in the piston chamber as a measurement value. A closure element 20 is arranged at the lower end of the nose cone 11a. Here, the closure element 20 is a plug which can be plugged onto the nose cone for completely closing the suction channel 19 in the closed position. The closure element 20 serves as a resistance device in a functional checking in order to oppose to the fluid flow, in this case the air flow of the air cushion pipette 1b. The suction channel is completely blocked. A closure element 20 can also be used when executing a functional checking on the pipetting apparatus 1, 1 and 1a.

[0125] The pipetting apparatus 1, 1, 1a, 1b serves for pipetting fluid samples in a laboratory. It comprises a suction mechanism that comprises an electrically powered motor (14), a piston chamber (18) and a piston element (12) arranged movably therein, driven by the motor, and by the movement of which the suction of a fluid is effectuated by the formation a fluid flow through an open suction channel (19) of the piston chamber. The pipetting apparatus also comprises the data processing control device 15 that comprises at least one data storage device 15a. It contains a measurement device 16a for detecting the motor current drawn by the motor 14, or a pressure sensor 16b for detecting the chamber pressure, as a measurement value for characterizing the physical work performed by the electrically powered movement of this piston element 12 by means of the suction mechanism.

[0126] The control device 15 is configured to detect a performance state of the pipetting apparatus 1, 1, 1a, 1 b, in particular:

[0127] a) to acquire at least one value of this measurement value as a function of a defined movement of the piston element 12 (step 201 in FIG. 4)

[0128] b) to compare the at least one value of the measurement value with at least one reference value. (Step 202 in FIG. 4)

[0129] c) to store the at least one value of this measurement value in the data storage device 15a. (Step 203 in FIG. 4)

[0130] In this, step c) (203) canalternatively or additionallyalso be carried out before step b) (202).

[0131] The at least one reference value is stored in the data storage device 15a and therefore available. The reference value is determined by the manufacturer in the manufacturing process of pipetting apparatus and stored. In addition, the reference value can be updated by the service if components (e.g. motor, spindle) are exchanged in the event of a maintenance of the pipetting apparatus. The defined movement mentioned in step a) is here a suction movement of the piston element 12 (upward movement of the piston element 12) for aspirating the sample or an ejection movement for dispensing the sample. This movement is defined by a target volume that corresponds to a certain ideal end position of the piston element 12. The piston element 12 is therefore moved, starting from the initial situation, in which the atmospheric pressure is applied in the piston chamber, to the volume-determining end position in which a partial vacuum is applied in the piston chamber. Furthermore, the movement is defined by the pipetting rate. The at least one reference value contains at least one current value, in particular a series of current values, that were determined experimentally beforehand, e.g. by the manufacturer, with this pipette or at least one pipette of the same type, namely with exactly the movement used in step a) with the said target volume and the determined pipetting rate. The current values of the reference development Iref(t) were determined during the movement and are essentially proportional to the pressure in the sample chamber under normal conditions.

[0132] FIG. 3a depicts different piston positions of the pipetting apparatuses from FIGS. 2a and 2b while expanding the air in the piston chamber 18 by moving the piston 12 at a fixed speed upwards to a predetermined end position. The suction channel is closed with the closure element. A development of the reference measured values I.sub.mot(t) with respect to the piston positions in FIG. 3a is illustrated FIG. 3b; in the diagram, I.sub.mot(t) is symbolized by +. The central curve in the diagram can correspond to an ideal development according to the reference values, the upper and lower curve define a tolerance range which marks a fault-free state range of the pipette. The functional checking is carried out analogously and results in measured values, that are marked by x and o in the diagram. In particular, the comparison of a single measured value with a reference measurement value would be sufficient for executing the method, in particular the value acquired when reaching the target volume on the far right. The measurement series x illustrates an error condition, as the measured motor current is outside the tolerance range at this piston position, resp. at the moment of reaching the end position of the piston. By means of the functional checking method depicted in FIG. 3a, 3b, a leakage of the suction mechanism can be determined. Also, a contamination or wear of the suction mechanism can be detected, which can manifest itself in particular in an increased value of the measured motor current.

[0133] Similarly to FIG. 3a, FIG. 5a depicts different piston positions of the pipetting apparatuses from FIGS. 2a and 2b while expanding the air in the piston chamber 18 by moving the piston 12 at a fixed speed upwards to a predetermined end position. Again, the suction channel is closed with the closure element. A development of the reference measured values I.sub.mot(t) with respect to the piston positions in FIG. 5a is illustrated FIG. 5b; in the diagram, I.sub.mot(t) is symbolized by +. The central curve in the diagram can correspond to an ideal development according to the reference values, the upper and lower curve define a tolerance range which marks a fault-free state range of the pipette. The functional checking is carried out analogously and results in measured values, that are marked by x and o in the diagram. Unlike the method in FIG. 3a, 3b, in FIG. 5a, 5b the piston remainsin an additional step of the methodfor a defined period in its the position that is extended the farthest from the piston chamber, in particular when the maximum motor current is reached, and the motor is powered off. After a delay of e.g. 50 ms to 5 s, the motor is restarted and the measurement value motor current is acquired again. If the suction mechanism was working properly, in particular the piston chamber was sealed, the motor would power off immediately because of the maximum motor current being reachedthe last value of the measurement value would correspond to the penultimate value of the measurement value within the tolerance, which would manifest itself as the plateau range of the measurement curve. In the case of a leaky piston chamber depicted here, however, the measured motor current is outside the tolerance range, which represents a poor performance state of the pipetting apparatus. The corresponding information is output to the user, in particular via a display of the pipetting apparatus, and/or the measurement value is stored, for the purpose of documentation and/or subsequent evaluation. The measurement series x illustrates an error condition also here, as the measured motor current is outside the tolerance range at the moment the piston reaches the end position and after the waiting period. As a result, in particular a leak in the suction mechanism is detected.

[0134] FIG. 4a schematically depicts the workflow of the method 200 according to the present invention according to an embodiment on a pipetting apparatus, in which the measurement value consulted for the detection of at least one performance state of the pipetting suction mechanism of a pipetting apparatus (1; 1; 1a) is the motor current. The steps a) and b) are carried out a total of four times in order to acquire (201) and store (202) four measured values (1+n=3 repetitions) of the measurement value. Finally, a comparison is used to check whether the measured values are within a tolerance range (203). The method is executed preferably when the suction channel 19 is sealed with a sealing plug. In this way, a load state of the pipetting apparatus can be induced efficiently, which is particularly suitable for a functional checking.

[0135] FIG. 4b schematically depicts the workflow of the method 200 according to the present invention according to an embodiment on a pipetting apparatus, in which the measurement value consulted for the detection of at least one performance state of the pipetting suction mechanism of the pipetting apparatus (1, 1, 1a, 1b) is the pressure in the piston chamber. Other than that, the workflow of the method is analogous to the method 200 in from FIG. 4a.