Method for improved pipetting monitoring sensitivity and system for executing the same

Abstract

To provide a pipetting method capable of detecting abnormality at a pipetting process even when a disposable pipette end having a filter is used.SOLUTION: A pipetting method includes: (a) executing air suction of a pipette at least once by using a regulated pipetting parameter and measuring air pressure of a content volume of the pipette; (b) estimating filter resistance of a pipette end by using measured air pressure and a regulated pipetting parameter; (c) sucking liquid by a regulated pipetting parameter and measuring liquid suction pressure of a content volume of the pipette; (d) correcting liquid suction pressure by using the estimated filter resistor of the pipette and the regulated pipetting parameter; and (e) determining whether or not liquid pipetting is permissible by using the corrected liquid suction pressure.SELECTED DRAWING: None

Description

[Technical Field]

[0001] FIELD OF THE INVENTION The present invention relates generally to a method for pipetting liquids using a pipette with a disposable pipette tip having a filter and using calibration of pressure data to improve pipetting monitoring sensitivity and / or identify defective pipettes. [Background technology]

[0002] background Instruments (e.g., the x800 series and MagNA Pure24 / 96 systems) for pipetting and processing samples (e.g., mixing samples with reagents) using disposable pipette tips are used in molecular diagnostics and life science research and development. To assess the quality of the pipetting process, the pressure inside the pipette is usually measured during the liquid pipetting process and analyzed to detect abnormalities. However, frequently used disposable pipette tips typically contain aerosol filters to avoid cross-contamination between samples, and the varying pressure resistance of these filters can create difficulties in detecting abnormalities in the sample pipetting process. Summary of the Invention

[0003] overview One aspect of the invention relates to a method of calibrating a pipette, the pipette having an internal volume, a disposable pipette tip, and a filter separating the internal volume between the disposable pipette tip and the pipette, the method comprising performing at least one air aspiration of the pipette with defined pipetting parameters and measuring the air pressure in the internal volume of the pipette.

[0004] Another aspect of the present invention relates to systems and subsystems configured to perform the methods described herein, including the additional process steps of performing at least one air aspiration of the pipette with defined pipetting parameters and measuring the air pressure in the internal volume of the pipette.

[0005] The foregoing has outlined some of the aspects of the present invention. These aspects should not be construed as limitations on the invention, but merely as illustrations of some of the invention's more prominent features and applications. Numerous other beneficial results can be attained by modifying the embodiments within the scope of the invention. Therefore, for further objectives and a full understanding of the present invention, reference should be made to the following summary of the invention and the detailed description setting forth the preferred embodiments, as well as the scope of the invention as defined by the claims and the accompanying drawings. The specific features and operation of the present invention will be more readily understood from the specification and drawings. It is to be understood that the drawings are for purposes of illustration and description only. [Brief explanation of the drawings]

[0006] [Figure 1] 1 is a graph of the pressure in a pipette during air aspiration with defined pipetting parameters. [Figure 2] 1 is a graph of uncalibrated pressure in a pipette during liquid aspiration. [Figure 3] 10 is a graph of velocity dependent pressure for calibrating pressure measured from a pipette. [Figure 4] 1 is a graph of the calibrated pressure in a pipette when aspirating liquid. DETAILED DESCRIPTION OF THE INVENTION

[0007] Detailed Description In the following description, for purposes of explanation, specific details are set forth in order to provide a thorough understanding of various aspects of the present invention. However, it will be apparent to those skilled in the art that the invention as defined by the claims may include some or all of the features or embodiments described herein, and may further include obvious modifications and equivalents of the features and concepts described herein.

[0008] Definition: As used herein, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise.

[0009] Ranges can be expressed herein as from "about" one particular value and / or to "about" another particular value. When such a range is expressed, another aspect includes from the one particular value and / or to the other particular value. Similarly, when values ​​are expressed as approximations, by use of the antecedent "about," the particular value forms another aspect, and it is understood that "about" is utilized herein to express the degree of inherent uncertainty that may result from any quantitative comparison, value, measurement, or other representation. These terms are also utilized herein to express the degree to which quantitative representations may vary from the stated basis without resulting in a change in the basic functionality of the subject matter. It will be further understood that the endpoints of each range are significant both in relation to the other endpoint and independently of the other endpoint. When used in the claims herein, the term "about" in a claim refers to a + / - 10% variation from the nominal value. It is understood that such a variation is always included in any given value presented herein, whether or not specifically referred to.

[0010] Terms used herein such as "aspect" or "embodiment" or "exemplary" or "exemplified" are not intended to indicate preference, but rather to explain that the aspect discussed below is merely one example of the aspects presented.

[0011] Furthermore, as used herein, it should be noted that relative terms such as "substantially," "generally," and "approximately" are utilized herein to express the inherent degree of uncertainty that may result from any quantitative comparison, value, measurement, or other representation. These terms are also utilized herein to express the degree to which a quantitative representation may vary from the stated basis without resulting in a change in the basic functionality of the subject matter. When used in the claims herein, the term "substantially" in the claims refers to a + / - 10% variation from the nominal value. It should be understood that such a variation is always included in any given value presented herein, whether or not it is specifically referred to.

[0012] The term "connected to" includes directly or indirectly connected.

[0013] As used herein, the term "optional" or "optionally" means that the subsequently described event or circumstance may or may not occur, or the element may be omitted, and that the description includes cases where the event or circumstance occurs and cases where it does not occur, or where the element is present or absent.

[0014] The present invention relates generally to an improved method for pipetting liquids and a system configured to perform the same.

[0015] One aspect of the present invention relates to a method for performing pipetting of liquids that provides improved monitoring sensitivity, preferably by reducing errors and / or data spread caused by pipette filter variations and / or other pipette imperfections.

[0016] One embodiment of the present invention relates to a method for calibrating a pipette having an internal volume and a filter surrounding the internal volume, the method comprising performing at least one air aspiration of the pipette with defined pipetting parameters and measuring the air pressure in the internal volume of the pipette.

[0017] Therefore, the calibration method is preferably performed repeatedly by the pipetting instrument, preferably automatically, for up to 10 different disposable pipette tips, preferably up to 50 different disposable pipette tips, more preferably up to 100 different disposable pipette tips, and most preferably up to 1000 different disposable pipette tips.

[0018] Preferably, the defined pipetting parameters are selected from jerk, acceleration, velocity, and / or volume. The term "jerk" refers to the rate of change of "acceleration" at the beginning and end of aspiration. The term "acceleration" refers to the rate of change of "velocity" at the beginning and end of aspiration. The term "velocity" refers to the speed of gas flow during aspiration. The term "volume" refers to the volume of air or gas.

[0019] More preferably, the defined pipetting parameters include acceleration and velocity.According to a preferred embodiment, the filter is an aerosol filter.

[0020] According to one embodiment, pipette filters have different pressure resistances for different pipette tips (i.e., the filter resistance of filter A in disposable pipette A is different from the filter resistance of filter B in disposable pipette B), which can make it difficult to detect anomalies in the sample pipetting process. According to the present invention, after each pipette tip is picked up by the pipette-handling device component and before pipetting a sample, the pipetting device performs air aspiration at a given acceleration and velocity to measure the filter resistance. This measured filter resistance is then used to calibrate the pressure signal measured during sample pipetting / processing based on pipetting parameters (jerk, acceleration, velocity, volume). This significantly reduces the spread of the measured pressure curve, thus improving the performance of pipetting monitoring.

[0021] Below is a detailed description of the calibration process according to one embodiment of the present invention.

[0022] (1) As shown in Figure 1, air is aspirated with the specified pipetting parameters (jerk, acceleration, velocity, volume) to obtain the pressure P air Figure 1 shows the pressure [Pa] within the pipette volume over time [s] during air aspiration according to the present invention.

[0023] (2) As shown in Figure 2, liquid is aspirated with the specified pipetting parameters (jerk, acceleration, velocity, volume), and the internal pressure P asp Figure 2 shows the pressure [Pa] (uncalibrated) within the pipette volume over time [s] during liquid aspiration.

[0024] (3) Estimation of filter resistance: When air is aspirated (1), the pipetting device is operated at a constant aspiration speed V asp When P is reached, the flow rate through the aerosol filter is constant and equal to the suction rate. air(t@v = constant) is also constant (signal fluctuations due to the pipetting device can be averaged, or the pressure can be estimated using other suitable methods such as median filtering). Therefore, the pressure drop measured by the pressure sensor, Δp = P air (t@v=constant)-P air (0) is calculated by using the known suction speed to calculate the filter resistance R F can be converted to R F =Δp / V asp Depending on the jerk, acceleration, and volume of the suction, When suctioning, the speed does not always reach a constant stage. The maximum suction speed is determined by the jerk, acceleration, and Using the maximum measured pressure drop, which can be calculated from the suction volume, The filter resistance can be calculated similarly.

[0025] (4) Liquid Aspiration Calibration: 1. Aspiration rate of the pipetting device as a function of time V asp (t) is calculated based on the aspiration parameters (jerk, acceleration, velocity, volume). 2.V asp (t) and the measured filter resistance R F Using The pressure drop ΔP caused by the filter as a function of time during aspiration Filter Calculate (as shown in Figure 3). ΔP Filter (t)=R F *V asp (t) Figure 3 shows the velocity pressure [Pa] drop caused by the filter in the pipette.

[0026] 3. Pressure P measured during the suction process asp (t), Calculated filter pressure drop ΔP Filter Calibrate with (t). Pcalibrated (t)=P asp (t)-ΔP Filter (t) 5) This allows pressure-based pipetting monitoring to be performed calibrated This can be done using (t). Figure 4 shows the calibrated pressure inside the pipette when aspirating liquid. As can be seen, the spread of the data is reduced by about 400 Pa.

[0027] Thus, the methods described herein preferably improve monitoring sensitivity by reducing error and / or data spread caused by pipette filter variations and / or other pipette imperfections.

[0028] Another embodiment of the invention relates to a method of pipetting a volume of liquid using a pipette having an internal volume and a disposable pipette tip having a filter surrounding the internal volume, the filter having a filter resistance, the method comprising: (a) performing at least one air aspiration of the pipette with defined pipetting parameters and measuring the air pressure in the internal volume of the pipette; (b) estimating the filter resistance of the filter in the disposable pipette tip using the measured air pressure and the defined pipetting parameters; (c) performing aspiration of liquid with defined pipetting parameters and measuring the liquid aspiration pressure of the internal volume of the pipette; (d) correcting the liquid aspiration pressure using the estimated filter resistance of the pipette and the defined pipetting parameters; (e) using the corrected liquid aspiration pressure to determine whether pipetting of a volume of liquid was acceptable or unacceptable; Includes:

[0029] The term "acceptable / unacceptable" depends on the margin of error allowed by the method (e.g., according to preferred embodiments, deviations in the aspirated volume of more than ±10% or ±20% are not allowed).

[0030] Preferably, the defined pipetting parameter is selected from jerk, acceleration, velocity, and / or volume. More preferably, the defined pipetting parameter includes acceleration and velocity. According to a preferred embodiment, performing at least one air aspiration is performed at an acceleration and velocity selected to measure the filter resistance.

[0031] According to a preferred embodiment, the filter is an aerosol filter.

[0032] Preferably, the liquid is from a sample and the filter is configured to avoid cross-contamination of the sample.

[0033] Preferably, the method further comprises treating the liquid in the internal volume of the pipette.

[0034] Preferably, the method further comprises mixing the liquid in the internal volume of the pipette.

[0035] According to a preferred embodiment, performing at least one air aspiration comprises reaching a constant air aspiration rate in the pipette and a constant air flow rate through the filter. Preferably, the air aspiration rate is of the same order of magnitude as the aspiration rate when aspiration of a liquid, and the volume is preferably large enough to reach a constant air flow rate through the filter in 0.1 seconds to achieve a reliable measurement of the filter resistance.

[0036] According to another preferred embodiment, measuring the air pressure in the internal volume of the disposable pipette is performed using at least one pressure sensor.

[0037] Preferably, the method further comprises calibrating the aspiration of the liquid using the estimated filter resistance.

[0038] According to another preferred embodiment, the at least one air aspiration comprises aspiration using ambient air, pure oxygen, nitrogen, or other gases, or mixtures thereof. Preferably, ambient air at room temperature is used.

[0039] One aspect of the present invention relates to detecting a defective or missing filter using the methods described herein, specifically using the measured filter resistance to determine whether the filter is missing, defective, properly seated in the pipette, or other defects.

[0040] Another embodiment relates to a method of pipetting a volume of liquid using a pipette having an internal volume and a disposable pipette tip having a filter surrounding the internal volume, the filter having a filter resistance, the method comprising: (a) performing at least one air aspiration of the pipette with defined pipetting parameters and measuring the air pressure in the internal volume of the pipette; (b) estimating the filter resistance of the filter in the disposable pipette tip using the measured air pressure and the defined pipetting parameters; (c) delivering liquid at prescribed pipetting parameters and measuring the liquid delivery pressure of the internal volume of the pipette; (d) correcting the liquid delivery pressure using the estimated filter resistance of the pipette and the defined pipetting parameters; and preferably (e) using the corrected liquid delivery pressure to determine whether the pipetting of a volume of liquid was acceptable or unacceptable; Includes:

[0041] Another embodiment relates to a method of pipetting a volume of liquid using a pipette having an internal volume and a disposable pipette tip having a filter surrounding the internal volume, the filter having a filter resistance, the method comprising: (a) performing at least one air aspiration of the pipette with defined pipetting parameters and measuring the air pressure in the internal volume of the pipette; (b) estimating the filter resistance of the filter in the disposable pipette tip using the measured air pressure and the defined pipetting parameters; (c) performing aspiration of liquid with prescribed pipetting parameters and measuring the liquid aspiration pressure of the internal volume of the pipette; Includes:

[0042] According to an alternative embodiment, instead of subtracting the pressure drop caused by the filter, the deviation / difference from a predetermined reference pressure drop can be calculated and subtracted. This is useful when a large set of pressure data already exists without filter calibration. This predetermined reference pressure drop can be used to correct newly acquired data with deviating filter pressures to the average of the existing data set. This allows existing parameters for pipetting monitoring to be reused.

[0043] Therefore, one preferred alternative embodiment is (a) performing at least one air aspiration of the pipette with defined pipetting parameters and measuring the air pressure in the internal volume of the pipette; (b) using the measured air pressure and the specified pipetting parameters to estimate the deviation of the filter resistance of the filter in the disposable pipette tip from a predetermined reference pressure drop; (c) performing aspiration of liquid with defined pipetting parameters and measuring the liquid aspiration pressure of the internal volume of the pipette; (d) correcting the liquid aspiration pressure using the estimated deviation of the filter resistance of the pipette and the defined pipetting parameters; The present invention relates to a method comprising:

[0044] Preferably, the method further comprises using the corrected liquid aspiration pressure to determine whether the pipetting of the volume of liquid was acceptable or unacceptable.

[0045] Another aspect of the present invention relates to systems and subsystems configured to perform the methods described herein, including the additional process steps of performing at least one air aspiration of the pipette with defined pipetting parameters and measuring the air pressure in the internal volume of the pipette.

[0046] According to one embodiment, the system is programmed or reprogrammed to perform additional process steps.

[0047] According to another embodiment, the system is programmed or reprogrammed to perform the following process steps:

[0048] Algorithm 1: Step 1: Receive a request to perform a method that includes calibrating a pipette. Step 2: Remember the received request.

[0049] Algorithm 2: Step 1: Perform at least one air aspiration of the pipette with the prescribed pipetting parameters and measure the air pressure of the pipette's internal volume. Step 2: Store the measured air pressure.

[0050] Algorithm 3: Step 1: Estimate the filter resistance of the filter in the disposable pipette tip using the measured air pressure and defined pipetting parameters. Step 2: Store the estimate of the filter resistance of the filter in the disposable pipette tip.

[0051] Algorithm 4: Step 1: Perform aspiration of liquid with the specified pipetting parameters and measure the liquid aspiration pressure of the internal volume of the pipette. Step 2: The measured liquid suction pressure is stored.

[0052] Algorithm 5: Step 1: Correct the liquid aspiration pressure using the estimated filter resistance of the pipette tip and the defined pipetting parameters. Step 2: Store the corrected liquid aspiration pressure.

[0053] Algorithm 5: Step 1: Perform an analysis of the corrected liquid aspiration pressure to determine whether the pipetting of a volume of liquid was acceptable or unacceptable. Step 2: Store the determination of whether the pipetting of a volume of liquid was acceptable or unacceptable.

[0054] According to another embodiment, the system is programmed or reprogrammed to perform the process steps of the alternative method.

[0055] Alternative Algorithm 1: Step 1: Receive a request to perform a method that includes calibrating a pipette. Step 2: Remember the received request.

[0056] Alternative Algorithm 2: Step 1: Perform at least one air aspiration of the pipette with the prescribed pipetting parameters and measure the air pressure of the pipette's internal volume. Step 2: Store the measured air pressure.

[0057] Alternative Algorithm 3: Step 1: Using the measured air pressure and defined pipetting parameters, estimate the deviation from a predetermined reference pressure drop for the filter resistance of the filter in the disposable pipette tip. Step 2: Memorize the estimated deviation of the filter resistance of the filter in the disposable pipette tip.

[0058] Alternative Algorithm 4: Step 1: Perform aspiration of liquid with the specified pipetting parameters and measure the liquid aspiration pressure of the internal volume of the pipette. Step 2: The measured liquid suction pressure is stored.

[0059] Alternative Algorithm 5: Step 1: Correct the liquid aspiration pressure using the estimated deviation of the filter resistance at the pipette tip and the defined pipetting parameters. Step 2: Store the corrected liquid aspiration pressure.

[0060] Alternative Algorithm 6: Step 1: Perform an analysis of the corrected liquid aspiration pressure to determine whether the pipetting of a volume of liquid was acceptable or unacceptable. Step 2: Store the determination of whether the pipetting of a volume of liquid was acceptable or unacceptable.

[0061] In the above description, for purposes of explanation only, specific nomenclature is set forth in order to provide a thorough understanding of the present disclosure. However, it will be apparent to those skilled in the art that these specific details are not required to practice the teachings of the present disclosure.

[0062] Some portions of the detailed descriptions herein are presented in terms of algorithms and symbolic representations of operations on data bits within a computer memory. These algorithmic descriptions and representations are the means used by those skilled in the data processing arts to most effectively convey the substance of their work to others skilled in the art. An algorithm is here, and generally, conceived to be a self-consistent sequence of steps leading to a desired result. These steps require physical manipulations of physical quantities. Usually, though not necessarily, these quantities take the form of electrical or magnetic signals capable of being stored, transferred, combined, compared, and otherwise manipulated. It has proven convenient at times, principally for reasons of common usage, to refer to these signals as bits, values, elements, symbols, characters, terms, numbers, or the like.

[0063] It should be borne in mind, however, that all of these and similar terms are associated with the appropriate physical quantities and are merely convenient labels applied to these quantities. As will become apparent from the following description, unless otherwise indicated, throughout this specification, descriptions utilizing terms such as "processing" or "computing" or "calculating" or "determining" or "displaying" will be understood to refer to the operations and processing of a computer system or similar electronic computing device that manipulates and transforms data represented as physical (electronic) quantities in the computer system's registers and memory into other data similarly represented as physical (electronic) quantities in the computer system's memory or registers or other such information storage, transmission, or display device.

[0064] Additionally, the present disclosure relates to apparatus for performing the operations herein. This apparatus may be specially constructed for the required purposes, or it may comprise a general-purpose computer selectively activated or reconfigured by a computer program stored in the computer. Such computer program may be stored on a computer-readable storage medium, such as, but not limited to, any type of disk, including floppy disks, optical disks, CD-ROMs, and magneto-optical disks, read-only memory (ROM), random-access memory (RAM), EPROM, EEPROM, magnetic or optical cards, or any type of medium suitable for storing electronic instructions, each coupled to a computer system bus.

[0065] The algorithms presented herein are not inseparably related to any particular computer or other apparatus. Various general-purpose systems, computer servers, or personal computers may be used with programs in accordance with the teachings herein, or it may prove convenient to construct more specialized apparatus to perform the required method steps. The required structure for a variety of these systems will be apparent from the description herein. It will be understood that a variety of programming languages ​​may be used to implement the teachings of the disclosure as described herein.

[0066] Furthermore, various features of the representative examples and dependent claims may be combined in ways not specifically and explicitly stated to provide further useful embodiments of the present teachings. Furthermore, it is expressly pointed out that any indication of a range of values ​​or a group of entities discloses all possible intermediate values ​​or intermediate entities for the purposes of the original disclosure and for the purposes of limiting the subject matter recited in the claims. It is also expressly pointed out that the dimensions and shapes of the components shown in the drawings are designed to aid in understanding how the present teachings may be implemented and are not intended to be limiting to the dimensions and shapes shown in the examples.

[0067] The scope of the present apparatus, systems, methods, etc. encompasses both means plus function and step plus function concepts. However, the claims should not be construed as indicating a means plus function relationship unless the word "means" is specifically recited in the claim, and should be construed as indicating a means plus function relationship when the word "means" is specifically recited in the claim. Similarly, the claims should not be construed as indicating a step plus function relationship unless the word "step" is specifically recited in the claim, and should be construed as indicating a step plus function relationship when the word "step" is specifically recited in the claim.

[0068] It is understood that the embodiments described herein are for illustrative purposes and should not be considered as limiting the subject matter of the present disclosure.

Claims

1. 1. A method for pipetting a volume of liquid using a pipette having an internal volume and a disposable pipette tip having a filter surrounding the internal volume, the filter having a filter resistor, the method comprising: (a) performing at least one air aspiration of the pipette with defined pipetting parameters and measuring the air pressure in the internal volume of the pipette; (b) estimating the filter resistance of the filter in the disposable pipette tip using the measured air pressure and the defined pipetting parameters; (c) performing an aspiration of the liquid with defined pipetting parameters and measuring the liquid aspiration pressure of the internal volume of the pipette; (d) correcting the liquid aspiration pressure using the estimated filter resistance of the pipette and the defined pipetting parameters; (e) using the corrected liquid aspiration pressure to determine whether the pipetting of the volume of the liquid was acceptable or unacceptable; A method comprising:

2. 1. A method for pipetting a volume of liquid using a pipette having an internal volume and a disposable pipette tip having a filter surrounding the internal volume, the filter having a filter resistor, the method comprising: (a) performing at least one air aspiration of the pipette with defined pipetting parameters and measuring the air pressure in the internal volume of the pipette; (b) estimating the filter resistance of the filter in the disposable pipette tip using the measured air pressure and the defined pipetting parameters; (c) delivering the liquid with defined pipetting parameters and measuring the liquid delivery pressure of the internal volume of the pipette; (d) correcting the liquid delivery pressure using the estimated filter resistance of the pipette and the defined pipetting parameters; (e) using the corrected liquid delivery pressure to determine whether the pipetting of the amount of liquid was acceptable or unacceptable; A method comprising:

3. 1. A method for pipetting a volume of liquid using a pipette having an internal volume and a disposable pipette tip having a filter surrounding the internal volume, the filter having a filter resistor, the method comprising: (a) performing at least one air aspiration of the pipette with defined pipetting parameters and measuring the air pressure in the internal volume of the pipette; (b) estimating the filter resistance of the filter in the disposable pipette tip using the measured air pressure and the defined pipetting parameters; (c) performing aspiration of the liquid with defined pipetting parameters and measuring the liquid aspiration pressure of the internal volume of the pipette; A method comprising:

4. The method of claim 2 , wherein the defined pipetting parameters include acceleration and velocity.

5. The method of claim 2 , wherein performing the at least one air suction is performed at an acceleration and speed selected to measure the filter resistance.

6. The method of claim 2 , wherein the filter is an aerosol filter.

7. The method of claim 2 , wherein the liquid is from a sample and the filter is configured to avoid cross-contamination of the sample.

8. The method of claim 2 , further comprising processing the liquid within the internal volume of the pipette.

9. The method of claim 2 , further comprising mixing the liquid within the internal volume of the pipette.

10. 3. The method of claim 2, wherein performing the at least one air aspiration comprises reaching a constant air aspiration rate at the pipette and a constant air flow rate through the filter.

11. 3. The method of claim 2, wherein measuring the air pressure in the internal volume of the disposable pipette is performed using at least one pressure sensor.

12. The method of claim 2 , further comprising calibrating the aspiration of the liquid using the estimated filter resistance.

13. 3. The method of claim 2, wherein the at least one air aspiration comprises aspiration using ambient air, pure oxygen, nitrogen, or other gas, or a mixture thereof.

14. The method of claim 2 further comprising detecting a defective or missing filter.

15. A system for performing sample pipetting of a liquid sample, the system being configured to perform the method of claim 2.

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