Patent Application
20250138041
The present invention relates to an automated pipetting apparatus arranged to automatically aspirate, transfer and dispense a liquid, for example a biological sample or a reagent.
The term pipetting refers to pipettes—a laboratory instrument commonly used to complete transport operations of small quantities of liquid, even in the order of microliters.
Compared to conventional manual micro-pipettes, such fully automated equipment has the advantage of improving the speed of execution of liquid aspiration and release operations, increasing the repeatability of the operations performed, as well as precision and accuracy, and ensuring the traceability of the process.
According to the conventional technique, such automated equipment comprises a pipetting head, which includes the components necessary to transfer the liquid from a vessel—containing the liquid to be collected—to the head, and vice versa. Typically, pipetting heads can be multi-channel or single-channel. The necessary precision in positioning the pipetting head in the source and destination liquid vessel is obtained thanks to the use of multi-axis systems controlled by one or more actuators.
Liquid transfer occurs by aspirating the desired volume of liquid from a source vessel, transferring it to one or more destination vessels. The commonly used technique to aspirate or dispense the liquid is based on an air displacement, along at least one duct, within the pipetting head. This technique can be used in manual, semi-automated or fully automated pipetting equipment.
In accordance with the prior art, the air displacement can be generated by means of piston pumps, pressurized vacuum/air pumps or volumetric pumps.
According to what is described in document EP 3014283 B1, such equipment can comprise a flow sensor arranged to monitor pipetting operations by measuring the displaced air volumes, wherein the flow sensor is based on a measurement of the pressure gap along a duct within the pipetting head.
The present invention starts from the desire to propose an automated pipetting apparatus for an analysis laboratory, which overcomes various operating limits of the previously indicated prior art.
The main drawback of a solution including a precision syringe lies in the manufacturing complexity of the same with equal miniaturization. In fact, high accuracy and precision position sensors and various components with tight tolerances are necessary to realize the mechanical transmission and the syringe body. These requirements therefore involve, in addition to the high cost, a lower reliability and a degradation of performance in operation.
Regarding a solution based on a pressure drop flow sensor, the main limitation is the technology required to achieve a drop proportional to the flow in an acceptable range of pressures to be measured.
The main object of the present invention is to overcome the drawbacks of the known solutions.
In particular, an object of the present invention is to provide an automated pipetting apparatus, and a related process for aspiration and dispensing of a volume of liquid, which on the one hand maintains a high degree of reliability in terms of precision of the pipetting operations and the related repeatability, and on the other hand allows to significantly increase productivity compared to the conventional totally manual process.
A further object of the present invention is to increase the degree of traceability of the operations performed, the errors found and the performances obtained.
A further object of the present invention is to provide an apparatus and a related process of the aforementioned type which guarantees a high degree of safety against the risk of errors, concerning both the volume of aspirated/dispensed liquid and the control of the displacement of the pipetting head from a source vessel to a destination vessel.
A further object of the invention is to realize an apparatus and a related process of the aforementioned type which allows to obtain an extremely precise control of the volume of aspirated/dispensed liquid.
A further object of the invention is to provide an apparatus and a process of the aforementioned type which have a high degree of flexibility, in the sense of being able to operate with different types of liquids with different viscosities and in association with other automated equipment of an analysis laboratory.
Yet a further object of the invention is to achieve all the aforementioned objectives with relatively simple and relatively low cost means.
In order to achieve one or more of the aforementioned objects, the invention relates to the features indicated in the attached claim 1.
The present invention also relates to the process which is carried out by means of the aforementioned apparatus.
Further features of the invention are indicated in the attached claims.
Further features and advantages of the invention will be clear from the following description with reference to the attached drawings, provided purely by way of non-limiting example, in which:
The following description illustrates various specific details aimed at a thorough understanding of examples of one or more embodiments. The embodiments can be made without one or more of the specific details, or with other methods, components, materials, etc. In other cases, known structures, materials or operations are not shown or described in detail to avoid obscuring various aspects of the embodiments. Reference to “an embodiment” within this description means that a particular configuration, structure or feature described in relation to the embodiment is included in at least one embodiment. Thus, phrases such as “in one embodiment”, possibly present in different places in this description, do not necessarily refer to the same embodiment. Furthermore, particular conformations, structures or features can be suitably combined in one or more embodiments and/or associated with the embodiments in a different way from as illustrated here, so for example a feature exemplified here in relation to a figure can be applied to one or more embodiments exemplified in a different figure.
The references illustrated herein are for convenience only and therefore do not limit the scope of protection or the extent of the embodiments.
In
The apparatus 1 comprises pipetting means 2 configured to automatically aspirate and dispense a liquid, for example a biological sample or a reagent. The pipetting means 2 comprise at least one pipetting head 6 arranged to aspirate and/or dispense relatively small volumes of liquids, even in the order of microliters. The apparatus 1 comprises robotic means 11 configured to perform a relative displacement between the pipetting means 2 and a vessel (for example a test tube) containing the liquid to be aspirated and/or dispensed along at least one direction.
According to what is illustrated in
In accordance with the embodiment illustrated in
Naturally, the robotic means 11 may differ from what is described above and illustrated in
It should be noted that the pipetting apparatus 1 according to the invention comprises at least one electronic controller E (schematically illustrated in
According to the invention, the apparatus 1 comprises an air displacement system for aspirating and dispensing a determined volume of liquid, including a pressure and vacuum source 3 arranged to create the pressure necessary to carry out a dispensing operation and/or the vacuum condition to carry out an operation of aspiration of a volume of liquid.
The pressure and vacuum source 3 is connected to the pipetting head 6 by means of a pneumatic circuit including a first duct 16. As will be evident from the following description, the pneumatic circuit also comprises at least a second duct arranged within the pipetting head 6, to convey the air displacement generated by the pressure and vacuum source 3. Naturally, to allow the displacement of the pipetting head 6, the first duct 16 is a flexible duct which allows to carry out the displacement of the head 6 away from the source 3.
The pipetting head 6 comprises a casing 17, preferably parallelepiped-shaped, within which a plurality of components necessary to carry out the pipetting operations are mounted. A tip adapter element 15, protruding from the casing 17, comprises an end portion 22 arranged to perform the mounting—preferably by interference—of a pipetting tip 21 (shown in
As previously indicated, the automated pipetting apparatus 1 carries out the pipetting operations by means of an air displacement system comprising the pressure and vacuum source 3. Within the casing 17 of the head 6, an internal duct 9 is arranged to convey the air displacement generated by the pressure and vacuum source 3. The references 9′ and 9″ indicate, respectively, a first portion of the internal duct 9 obtained within the casing 17, and a second portion of the internal duct 9 obtained within the tip adapter element 15. The end portion 22 includes an end orifice to allow the passage of air necessary for the displacement of the liquid within the tip 21, and the accumulation of the aspirated liquid.
Preferably, the apparatus 1 comprises an abutment element 23 having an upper portion 23′ connected to the casing 17 and a lower portion 23″ axially aligned and superimposed on an upper portion of the tip adapter element 15. The abutment element 23 is configured to slide along the axis of the tip adapter element 15—in the direction of the casing 17—when the tip 21 is mounted on the tip adapter element 15, so as to sight at least one optical sensor arranged within the casing 17 and thus provide a confirmation signal of correct mounting of the tip 21.
Still according to a preferred feature, the head 6 comprises an air filter 24 arranged to avoid contamination of the air during the aspiration operations.
As previously indicated, within the casing 17 of the head 6, an internal duct 9 is arranged to convey the air displacement generated by the pressure and vacuum source 3, so as to carry out the operations of aspiration and dispensing of liquid. The references 9′ and 9″ indicate, respectively, a first portion of the internal duct 9 obtained within the casing 17, and a second portion of the internal duct 9 obtained within the tip adapter element 15. With the reference 18 is indicated a connector arranged to connect the internal duct 9 to the first duct 16 and an intake manifold 19 including a portion of the aforementioned first portion of duct 9′.
According to the invention, a first solenoid valve 4 is arranged within the pipetting head 6—in communication with the internal duct 9—, configured to control the leakage or retention of the air flow introduced by the source 3. The first solenoid valve 4 is in the closed position when the source 3 is activated to pressurize the pneumatic circuit. Preferably, the first solenoid valve 4 is configured in a normally closed position. Still with reference to
According to a relevant feature of the invention, the automated pipetting apparatus 1 comprises at least one flow sensor 8 arranged within the pipetting head 6 to detect the volume of aspirated/dispensed liquid by means of the pipetting tip 21. The flow sensor 8 is a MEMS (Micro Electro Mechanical System) thermal sensor based on a thermal detection principle which determines the deformation of a temperature profile generated by a heating element, in the presence of air flow, and detects the temperature gradient in the flow direction. The MEMS thermal sensor is a miniaturized sensor, sized to be integrated within the pipetting head 6, without negatively affecting the overall dimensions of the head. More specifically, the sensor is installed within the casing 17 of the head 6, in a position near the tip adapter element 15. Such position is particularly advantageous in terms of accuracy and repeatability on the handled volume. The miniaturization of the flow sensor 8 allows to make a head 6 of compact size, able to aspirate and dispense the liquid (biological sample, reagent, etc.) even in small-pitch containers, such as for example plates with a plurality of wells placed side by side with 9 mm interaxle spacing between one well and the other. These containers are provided by the SLAS (Society for Laboratory Automation and Screening) Standard. The small size of the head 6 including the miniaturized thermal sensor allow the simultaneous use of different pipetting heads—without hindering each other—to the advantage of a faster aspiration and dispensing process.
The operation of the apparatus 1, in accordance with the features described above, is as follows.
Initially, the printed circuit board 5 transmits an electric signal for opening the first solenoid valve 4, concurrently with the actuation of the source 3. After the reading of the deformation of the temperature profile, carried out by means of the flow sensor 8, the electronic controller E, programmed with retroactive control algorithms, uses the data collected by the flow sensor 8 to close the first solenoid valve 4, once the previously set volume of liquid to be aspirated/dispensed has been reached. The solenoid valve 4 is therefore in the open position for a certain period of time, determined as a function of the flow rate read by the flow sensor 8 and as a function of the volume to be aspirated/dispensed. In this regard, the apparatus 1 can comprise an HMI human-machine interface device, to carry out a preliminary programming of the apparatus, by entering various operating parameters, such as for example the type of liquid and the volume to be aspirated/dispensed. Therefore, according to the aforementioned specific configuration, the pressure and vacuum source 3 generates an air flow which flows through the first duct 16, an inlet section of the internal duct 9, the first solenoid valve 4, the flow sensor 8 which measures the flow rate of aspirated/dispensed liquid and the tip adapter element 15.
According to the embodiment illustrated in
The second solenoid valve 7 is configured in a normally closed position. The second solenoid valve 7 is switchable to collect liquid volumes in the order of microliters by exploiting the aforementioned portion of the pneumatic circuit comprised between the first solenoid valve 4 and the second solenoid valve 7 which—during operation—is at a certain pressure after the switching of the first solenoid valve 4. Thanks to this feature, it is performed an extremely precise control of the collection and dispensing operations of extremely little liquid volumes.
It should be noted that the second solenoid valve 7 can be made in a similar way to the first solenoid valve 4.
Still with reference to the embodiment illustrated in
As described in more detail below, the operation of the double solenoid valve configuration provides for the opening of the first solenoid valve 4, thus putting pressure on the portion of the pneumatic circuit comprised between the first solenoid valve 4 and the second solenoid valve 7. By closing the first solenoid valve 4 and by exploiting the volume of pneumatic circuit between the two solenoid valves, it is possible to switch the second solenoid valve 7 for very short times, of the scale of milliseconds (for example from 5 ms to 100 ms), thus making this portion of pneumatic circuit work as a constant volume micro-pump with a certain operating pressure.
The presence of the second solenoid valve 7 makes it possible to create a micro-pump with adjustable pressure, the benefits of which are:
Preferably, the apparatus 1 can comprise a pressure sensor (not shown in the drawings) arranged to read the pressure which is reached in the pneumatic circuit volume comprised between the two solenoid valves 4,7. The presence of a pressure sensor within the micro-pump allows to monitor the correct reaching of the desired pressure. Thanks to these features, the operating variables linked to the positioning of the source 3 at a certain distance from the pipetting tip 21 are eliminated, obtaining an extreme precision of the pipetting operations of volumes of liquid in the order of microliters, more particularly with volumes of liquid between 0.5 μl and 2 μl.
Naturally, in this embodiment with two solenoid valves, it is possible to operate as for the embodiment with a single solenoid valve, by opening the solenoid valves 4,7 and reading the information detected by the flow sensor 8, and then closing the solenoid valves 4,7 on reaching the previously set volume of aspirated/dispensed liquid.
Again with reference to the embodiment with two solenoid valves, a further operation (by implementing the micro-pump) is as follows:
having defined the internal volume of pneumatic circuit comprised between the first solenoid valve 4 and the second solenoid valve 7, the objective is to use this volume as a small internal reservoir to create the condition of pressure or vacuum. The pressure or vacuum level in the internal volume is reached by activating the first solenoid valve 4 (opening it to allow the passage of air, and subsequently closing it to put pressure on the portion of the circuit between the two solenoid valves). The pipetting apparatus 1 will therefore carry out micro-aspirations/micro-dispensing of liquid, eliminating any variable from the external pressure/vacuum source 3.
More specifically, the following steps are necessary to carry out the aforementioned micro-aspiration operation:
The following steps are necessary to carry out the aforementioned micro-dispensing operation:
As previously indicated, a pressure sensor associated with the described components allows to control the pressure in the internal volume comprised between the two solenoid valves 4,7, during all the steps of the aspiration and dispensing operations.
According to the embodiment illustrated in
The impulsive strategy—which is optimal for dispensing operations—is characterized by the typical peak produced on the flow curve and has the advantage of allowing a more efficient emptying of the liquid contained in the tip.
The strategy with a damped flow curve allows to obtain a more realistic and accurate integration of the flow signal, i.e. regular and without peak, both during the aspiration and the dispensing step.
It should therefore be noted that the electronic controller E is configured and programmed to implement the aforementioned different strategies, according to the specific application.
A second reduction connector 20′ can be used in a proximal position and upstream of the second solenoid valve 7, to obtain an optimal internal pressure in the volume of pneumatic circuit comprised between the two solenoid valves 4,7, obtaining a better correlation between the imposed pressure and the measured flow rate of aspirated/dispensed liquid.
Of course, even in the embodiment with two solenoid valves, an air filter 24 can be used to avoid air contamination during the aspiration/dispensing operation.
The accuracy of a pipetting apparatus can be defined by combining the following factors:
The calibration procedure comprises a step of set up of some operating parameters, which can influence the performance of a flow sensor arranged to read the flow rate of liquid aspirated/dispensed. The operating parameters are:
This set up procedure requires the use of a precision scale and comprises a repetitive execution of the following steps:
Even more in detail, as illustrated in the flow chart 30, the calibration procedure involves the following steps:
According to the invention, the calibration procedure described above can be completely automated, by configuring a controller of the apparatus 1 to control according to a predetermined sequence the pipetting means 2, the robotic means 11 and the scale which performs the weighing steps.
Studies and experiences conducted by the Applicant have shown that an automated pipetting apparatus according to the invention allows to obtain high reliability as regards the precision of the pipetting operations and the relative repeatability, as well as an extremely precise control of the volume of liquid aspirated/dispensed, while implementing relatively simple and low cost means.
A further aspect of the invention is illustrated below, related to a diagnostic algorithm that can be implemented with the previously described pipetting apparatus. The algorithm in question acts only for aspiration operations and not for dispensing. Therefore, according to a further feature of the invention, the electronic controller E is configured and programmed to implement a diagnostic procedure to detect any errors that occur during the aspiration process.
The electronic controller E is configured and programmed to detect one or more diagnostic events through the implementation of algorithms that are performed during the aspiration operations performed with the head 6, more particularly during an integration step of the target aspiration volume (online diagnostics) and at the end of aspiration (offline diagnostics).
During aspiration, the electronic controller E of the pipetting equipment is able to online detect two specific error events:
In case the electronic controller E identifies an error condition, the aspiration operations are automatically interrupted and/or the controller E transmits a warning signal of detected error.
With reference to the “clot” error event, the algorithm is based on the analysis of the flow signal during the single aspiration event, and in particular on the count of occurrences in which the difference between the flow value at an instant of time X and that at an instant of time X+N (N other than 1) is greater than a predefined amount. In order for the error to be detected, this count must exceed a suitable predetermined threshold value.
With reference to the “Air Aspiration” error event, since the flow values during aspirations of air only and liquid only do not differ significantly (in particular when the pipettor works with large volume tips), the implemented algorithm is based on the comparison between the corresponding pressure signals. In fact, during the aspiration step, negative pressures are used to generate the vacuum degree necessary for handling the sample. Based on the fact that, during aspirations of air only, the operating pressure settles to a value corresponding to a lower vacuum level than when liquid is aspirated, the implemented algorithm realizes that air is being aspirated when the pressure curve does not fall below the vacuum values typical of air aspirations.
At the end of the aspiration operations, on the basis of a processing and analysis step of the signal acquired through the flow sensor 8, the electronic controller E is configured and programmed to process said signal to detect other error events that occurred during aspiration. Specifically, the electronic control E is configured to execute an algorithm to search for one or more sudden variations on the flow signal, due to the transition in the aspiration step from air to liquid and vice versa.
This algorithm has two steps:
It should be noted that the previously described diagnostic algorithms can be implemented by a dedicated electronic unit, in communication with the electronic controller E able to control the pipetting means 2.
Naturally, without prejudice to the principle of the invention, the construction details and the embodiments may vary widely with respect to what is described and illustrated purely by way of example, without thereby departing from the scope of protection of the present invention, as defined in the attached claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 102021000021488 | Aug 2021 | IT | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/IB2022/057243 | 8/4/2022 | WO |
