Methods and systems for enhancing pipetting monitoring sensitivity.

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 Invention The present invention relates to a method for pipetting liquids, which generally uses a pipette equipped with a disposable pipette tip having a filter, and which uses calibration of pressure data to improve the sensitivity of pipetting monitoring and / or to identify defective pipettes. [Background technology]

[0002] background Instruments for pipetting and processing samples (e.g., mixing samples with reagents) using disposable pipette tips (e.g., x800 series, MagNA Pure24 / 96 system) are used in molecular diagnostics and life science research and development. To evaluate the quality of the pipetting process, the pressure inside the pipette is typically measured during the liquid pipetting process and analyzed to detect anomalies. However, disposable pipette tips, which are frequently used, typically contain aerosol filters to avoid cross-contamination between samples, and the varying pressure resistances of these filters can make it difficult to detect anomalies in the sample pipetting process. [Overview of the project]

[0003] overview One aspect of the present invention relates to a method for calibrating a pipette, wherein the pipette has an internal volume, a disposable pipette tip, and a filter that separates the internal volume between the disposable pipette tip and the pipette, and the method includes performing at least one air aspiration of the pipette with specified pipetting parameters and measuring the air pressure of the internal volume of the pipette.

[0004] Another aspect of the present invention relates to systems and subsystems configured to perform the method described herein, which includes an additional process step of performing at least one air aspiration of a pipette with defined pipetting parameters and measuring the air pressure of the internal volume of the pipette.

[0005] The above outlines some aspects of the present invention. These aspects should be construed not as limitations on the present invention, but merely as examples of some of the more prominent features and uses of the present invention. By modifying embodiments within the scope of the present invention, numerous other beneficial results can be obtained. Therefore, for other purposes and a complete understanding of the present invention, please refer to the summary of the present invention, as well as the detailed description illustrating preferred embodiments, in addition to the scope of the present invention as defined by the claims and accompanying drawings. The unique features and operation of the present invention will be more readily understood by this specification and the drawings. Please understand that the drawings are for illustrative and explanatory purposes only. [Brief explanation of the drawing]

[0006] [Figure 1] This graph shows the pressure inside the pipette during air aspiration with specified pipetting parameters. [Figure 2] This is a graph of the uncalibrated pressure inside the pipette during liquid aspiration. [Figure 3] This is a graph of velocity-dependent pressure used to calibrate the pressure measured from a pipette. [Figure 4] This is a graph of the calibrated pressure inside the pipette during liquid aspiration. [Modes for carrying out the invention]

[0007] Detailed explanation In the following description, specific details are provided for illustrative purposes to provide a complete understanding of the various aspects of the 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” refer to multiple objects unless the context otherwise explicitly indicates otherwise.

[0009] A range may be expressed herein as from a certain value about “about” and / or to another specific value about “about”. Where such a range is expressed, the other aspect includes this certain value and / or this other specific value. Similarly, where a value is expressed as an approximation using the antecedent “about”, that particular value forms the other aspect, and “about” will be understood herein to be used to express the degree of inherent uncertainty that may result from any quantitative comparison, value, measurement, or other expression. These terms are also used herein to express the extent to which a quantitative expression may deviate from a stated standard without resulting in a change in the fundamental function of the subject matter. It will be further understood that the endpoint of each range is significant both in relation to the other endpoint and independently of the other endpoint. Where used in the claims herein, the term “about” in a claim refers to a variation of + / - 10% from the nominal value. It should be understood that such variation is always included in any given value presented herein, whether specifically mentioned or not.

[0010] Terms used herein, such as “aspect,” “embodiment,” “exemplary,” or “exemplified,” are not intended to indicate priority, but rather to illustrate that aspects discussed later are merely examples of the aspects presented.

[0011] Furthermore, it should be noted that, as used herein, relative terms such as “substantially,” “generally,” and “approximately” are used to express the degree of inherent uncertainty that may arise from any quantitative comparison, value, measurement, or other expression. These terms are also used herein to express the extent to which a quantitative expression may deviate from the stated standard without altering the fundamental function of the subject matter. As used in the claims herein, the term “substantially” in a claim refers to a variation of + / - 10% from the nominal value. It should be understood that such variation is always included in any given value presented herein, whether specifically mentioned or not.

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

[0013] As used herein, the terms “optional” or “optionally” mean that the description includes cases where the event or situation described below occurs or does not occur, or where components are omitted, and that the description includes cases where the event or situation occurs and where it does not occur, or where components are present or absent.

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

[0015] One aspect of the present invention relates to a method of performing liquid pipetting that provides an improvement in monitoring sensitivity by reducing errors and / or data dispersion caused preferably by variations in pipette filters and / or other pipette defects.

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

[0017] Thus, this calibration method is preferably repeated, preferably automatically, by a pipetting instrument 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 start and end of aspiration. The term "acceleration" refers to the rate of change of "velocity" at the start and end of aspiration. The term "velocity" refers to the velocity of the gas flow during aspiration. The term "volume" refers to the amount 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 varying pressure resistances at each pipette tip (i.e., the filter resistance of filter A in disposable pipette A differs 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 has been picked up by the device component handling the pipette, and before pipetting the 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 diffusion of the measured pressure curve and therefore improves the performance of pipetting monitoring.

[0021] The following 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 drawn in with the specified pipetting parameters (jerk, acceleration, velocity, volume), and the pressure P inside the pipetting device is increased. air (t) is measured. Figure 1 shows the pressure [Pa] in 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 of the pipetting device asp (t) is measured. Figure 2 shows the pressure [Pa] (uncalibrated) in the pipette volume over time [s] during liquid aspiration.

[0024] (3) Estimation of filter resistance: When air is drawn in (1), a constant suction rate V is used in the pipetting device. asp When it reaches this point, the velocity of the flow through the aerosol filter is constant and equal to the suction velocity. At this stage, P air(t@v = constant) is also constant (signal fluctuations caused by the pipetting device can be averaged, or the pressure can be estimated using other appropriate methods such as median filtering). Therefore, the pressure drop Δp = P air (t@v = constant) - P air (0) can be converted to the filter resistance R F using a known suction rate. R F = Δp / V asp Depending on the jerk, acceleration, and volume of suction, it is not always possible to always reach a stage of constant speed during suction. In such cases, the maximum suction rate can be calculated from the jerk, acceleration, and suction volume, and the filter resistance can be calculated similarly using the maximum measured pressure drop.

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

[0026] 3. The pressure P asp ​​​​​​​calibrated (t)=P asp (t)-ΔP Filter (t) 5) This allows for pressure-based pipetting monitoring. calibrated This can be done using (t). Figure 4 shows the calibrated pressure inside the pipette during liquid aspiration. As shown in the figure, data diffusion is reduced by about 400 Pa.

[0027] Thus, the methods described herein have improved monitoring sensitivity, preferably by reducing errors and / or data diffusion caused by pipette filter variability and / or other pipette defects.

[0028] Another embodiment of the present invention relates to a method of pipetting a certain amount of liquid using a pipette having an internal volume and a disposable pipette tip having a filter surrounding the internal volume, wherein the filter has filter resistance, and this method (a) Perform at least one air aspiration of the pipette with the specified pipetting parameters and measure the air pressure in the internal volume of the pipette, (b) Estimate the filter resistance of the disposable pipette tip filter using the measured air pressure and specified pipetting parameters, (c) Perform liquid aspiration with the specified pipetting parameters and measure the liquid aspiration pressure in the internal volume of the pipette, (d) Compensating for the liquid aspiration pressure using the estimated filter resistance and specified pipetting parameters of the pipette, (e) Using the corrected liquid aspiration pressure, determine whether pipetting of a certain amount of liquid was acceptable or unacceptable. Includes.

[0029] The terms "acceptable / unacceptable" depend on the error range allowed by this method (for example, according to a preferred embodiment, deviations exceeding ±10% or ±20% in the aspirated volume are unacceptable).

[0030] Preferably, the defined pipetting parameters are selected from jerk, acceleration, velocity, and / or volume. More preferably, the defined pipetting parameters include acceleration and velocity. According to a preferred embodiment, at least one air aspiration is performed with the 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 a liquid from the sample, and the filter is configured to avoid cross-contamination of the sample.

[0033] Preferably, the method further includes processing the liquid contained within the internal volume of the pipette.

[0034] Preferably, the method further includes mixing the liquids in the internal volume of the pipette.

[0035] According to one preferred embodiment, performing at least one air aspiration includes reaching a constant air aspiration rate in the pipette and a constant airflow velocity through the filter. Preferably, the air aspiration rate is similar in magnitude to the aspiration rate used for liquid aspiration, and the volume is preferably large enough to reach a constant airflow through the filter for 0.1 seconds in order to achieve a reliable measurement of the filter resistance.

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

[0037] Preferably, the method further includes calibrating the liquid suction using the estimated filter resistance.

[0038] According to another preferred embodiment, at least one air suction includes suction 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 a method for detecting a defective filter or a missing filter using the method described herein. Specifically, the measured filter resistance is used to determine whether the filter is missing, whether the filter is defective, whether the filter is properly set in the pipette, or whether there are other defects.

[0040] Another embodiment relates to a method of pipetting a certain amount of liquid using a pipette having an internal volume and a disposable pipette tip having a filter surrounding the internal volume, wherein the filter has filter resistance, and this method (a) Perform at least one air aspiration of the pipette with the specified pipetting parameters and measure the air pressure in the internal volume of the pipette, (b) Estimate the filter resistance of the disposable pipette tip filter using the measured air pressure and specified pipetting parameters, (c) Dispense the liquid using the specified pipetting parameters and measure the liquid dispensing pressure through the internal volume of the pipette, (d) Compensating for the liquid delivery pressure using the estimated filter resistance and specified pipetting parameters of the pipette, preferably, (e) Using the corrected liquid delivery pressure, determine whether pipetting of a certain amount of liquid was acceptable or unacceptable. Includes.

[0041] Another embodiment relates to a method of pipetting a certain amount of liquid using a pipette having an internal volume and a disposable pipette tip having a filter surrounding the internal volume, wherein the filter has filter resistance, and this method (a) Perform at least one air aspiration of the pipette with the specified pipetting parameters and measure the air pressure in the internal volume of the pipette, (b) Estimate the filter resistance of the disposable pipette tip filter using the measured air pressure and specified pipetting parameters, (c) Perform liquid aspiration with specified pipetting parameters and measure the liquid aspiration pressure in 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 given reference pressure drop can be calculated and subtracted. This is useful when a large set of pressure data already exists without filter calibration. Using this given reference pressure drop, newly acquired data with deviated filter pressures can be corrected to the average of the existing dataset. This makes it possible to reuse existing parameters for pipetting monitoring.

[0043] Therefore, one preferred alternative embodiment is, (a) Perform at least one air aspiration of the pipette with the specified pipetting parameters and measure the air pressure in the internal volume of the pipette, (b) Using the measured air pressure and specified pipetting parameters, estimate the deviation of the filter resistance of the disposable pipette tip filter from a given reference pressure drop, (c) Perform liquid aspiration with the specified pipetting parameters and measure the liquid aspiration pressure in the internal volume of the pipette, (d) Compensating for the liquid aspiration pressure using the estimated deviation of the pipette's filter resistance and the specified pipetting parameters. Regarding methods including

[0044] Preferably, the method further includes using a corrected liquid suction pressure to determine whether pipetting of a certain amount of liquid was acceptable or unacceptable.

[0045] Another aspect of the present invention relates to systems and subsystems configured to perform the method described herein, which includes an additional process step of performing at least one air aspiration of a pipette with defined pipetting parameters and measuring the air pressure of 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 procedure 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 specified pipetting parameters and measure the air pressure in the pipette's internal volume. Step 2: Remember the measured air pressure.

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

[0051] Algorithm 4: Step 1: Perform liquid aspiration with the specified pipetting parameters and measure the liquid aspiration pressure in the pipette's internal volume. Step 2: Remember the measured liquid suction pressure.

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

[0053] Algorithm 5: Step 1: Perform an analysis of the corrected liquid suction pressure to determine whether pipetting a certain amount of liquid was acceptable or unacceptable. Step 2: Remember whether the pipetting of a certain amount 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 procedure 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 specified pipetting parameters and measure the air pressure in the pipette's internal volume. Step 2: Remember the measured air pressure.

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

[0058] Alternative Algorithm 4: Step 1: Perform liquid aspiration with the specified pipetting parameters and measure the liquid aspiration pressure in the pipette's internal volume. Step 2: Remember the measured liquid suction pressure.

[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 specified pipetting parameters. Step 2: Store the corrected liquid suction pressure.

[0060] Alternative Algorithm 6: Step 1: Perform an analysis of the corrected liquid suction pressure to determine whether pipetting a certain amount of liquid was acceptable or unacceptable. Step 2: Remember whether the pipetting of a certain amount of liquid was acceptable or unacceptable.

[0061] In the above description, certain terminology is used for illustrative purposes only and to provide a complete understanding of the disclosure. However, it will be apparent to those skilled in the art that these specific details are not necessary to carry out the teachings of the disclosure.

[0062] Some parts of the detailed description herein are presented with respect to algorithms and symbolic representations of operations on data bits in computer memory. The descriptions and representations of these algorithms are means used by those skilled in the field of data processing to most effectively convey the content of the study to others skilled in the field. Here, an algorithm is generally considered to be a self-consistent set of steps that produce a desired result. These steps require the physical manipulation of physical quantities. These quantities, though not always, usually take the form of electrical or magnetic signals that can be stored, transferred, combined, compared, and otherwise manipulated. It has sometimes proven convenient, primarily for reasons of common use, to refer to these signals as bits, values, elements, symbols, characters, terms, digits, etc.

[0063] However, it should be noted that all these terms and similar terms are merely convenient labels associated with and applied to appropriate physical quantities. As will be evident from the following explanations, unless otherwise specified, throughout this specification, any explanation using terms such as “process,” “calculate,” “compute,” “determine,” or “display” is understood to refer to the operation and processing of a computer system or similar electronic computing device that manipulates and converts data represented as physical (electronic) quantities in the registers and memory of a computer system to other data similarly represented as physical (electronic) quantities in the memory or registers of a computer system or other such information storage device, transmission device, or display device.

[0064] Furthermore, this disclosure relates to an apparatus for performing the operations described herein. This apparatus may comprise a general-purpose computer that is specifically configured for a particular purpose or that is selectively operated or reconfigured by a computer program stored in the computer. Such computer programs may be stored in computer-readable storage media, including, but not limited to, any type of disk such as 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 device. Various general-purpose systems, computer servers, or personal computers may be used with the programs taught herein, or may prove to be more convenient for constructing more specialized devices to perform the required method steps. The structures required for various such systems will become apparent from the description herein. It will be understood that various programming languages ​​may be used to implement the teachings of this disclosure as described herein.

[0066] Furthermore, various features of representative embodiments and dependent claims may be combined in ways not specifically and explicitly described to provide further useful embodiments of this teaching. It should also be explicitly noted that all representations of value ranges or groups of entities disclose any possible intermediate values ​​or intermediate entities with respect to the purposes of the original disclosure and the purposes of limiting the subject matter described in the claims. It should also be explicitly noted that the dimensions and shapes of the components shown in the drawings are designed to aid in understanding how this teaching is carried out and are not intended to limit the dimensions and shapes shown in the examples.

[0067] The scope of this apparatus, system, and method includes both means-plus function and step-plus function concepts. However, a claim should not be interpreted as indicating a means-plus function relationship unless the word "means" is specifically stated in the claim, and should be interpreted as indicating a means-plus function relationship unless the word "means" is specifically stated in the claim. Similarly, a claim should not be interpreted as indicating a step-plus function relationship unless the word "step" is specifically stated in the claim, and should be interpreted as indicating a step-plus function relationship unless the word "step" is specifically stated in the claim.

[0068] The embodiments described herein are for illustrative purposes only and should not be considered to limit the subject matter of this disclosure.

Claims

1. A method for pipetting a certain amount of liquid using a pipette having an internal volume and a disposable pipette tip having a filter surrounding the internal volume, wherein the filter has filter resistance, and the method is (a) to perform at least one air aspiration of the pipette with specified pipetting parameters and measure the air pressure in the internal volume of the pipette, wherein the specified pipetting parameters include at least one of jerk, acceleration, velocity, and volume, (b) Estimating the filter resistance of the filter at the tip of the disposable pipette using the measured air pressure and the specified pipetting parameters, (c) Performing aspiration of the liquid with the specified 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 and specified pipetting parameters of the pipette, (e) Using the corrected liquid suction pressure, determine whether the pipetting of a certain amount of the liquid was acceptable or unacceptable. A method that includes this.

2. A method for pipetting a certain amount of liquid using a pipette having an internal volume and a disposable pipette tip having a filter surrounding the internal volume, wherein the filter has filter resistance, and the method is (a) to perform at least one air aspiration of the pipette with specified pipetting parameters and measure the air pressure in the internal volume of the pipette, wherein the specified pipetting parameters include at least one of jerk, acceleration, velocity, and volume, (b) Estimating the filter resistance of the filter at the tip of the disposable pipette using the measured air pressure and the specified pipetting parameters, (c) Dispensing the liquid with the specified pipetting parameters and measuring the liquid dispensing pressure of the internal volume of the pipette, (d) Correcting the liquid delivery pressure using the estimated filter resistance and specified pipetting parameters of the pipette, (e) Using the corrected liquid delivery pressure, determine whether the pipetting of a certain amount of the liquid was acceptable or unacceptable. A method that includes this.

3. The method according to claim 2, wherein the defined pipetting parameters include acceleration and velocity.

4. The method according to claim 2, wherein the at least one air suction is performed at an acceleration and velocity selected to measure the filter resistance.

5. The method according to claim 2, wherein the filter is an aerosol filter.

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

7. The method according to claim 2, further comprising processing the liquid in the internal volume of the pipette.

8. The method according to claim 2, further comprising mixing the liquid in the internal volume of the pipette.

9. The method according to claim 2, wherein performing the at least one air aspiration includes reaching a constant air aspiration rate in the pipette and a constant airflow velocity through the filter.

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

11. The method according to claim 2, further comprising calibrating the suction of the liquid using the estimated filter resistance.

12. The method according to claim 2, wherein the at least one air suction includes suction using ambient air, pure oxygen, nitrogen, or other gases, or mixtures thereof.

13. The method according to claim 2, further comprising detecting a defective filter or a missing filter.

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

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