JPWO2019133683A5 - - Google Patents

Description

Cross-reference to related applications

This application is related to U.S. Provisional Application No. 62/611,261, filed Dec. 28, 2017, entitled "Apparatus and Method for Performing Automated Liquid Class Dispense" under 35 U.S.C. §119(e). and claims priority from US Provisional Application No. 62/611,261. The entire specification of this application is incorporated as part of this specification.

The subject matter of the present invention relates generally to methods of processing liquids, and more particularly to devices and methods for automated liquid transfer optimized dispensing.

Automated liquid handling equipment includes robots that are used to transfer predetermined amounts of liquids, such as reagents or samples, between predetermined containers. Liquid handling instruments are useful in a variety of applications including cell biology, genomics, forensics, and drug research. This instrument helps those with repetitive tasks transferring large ranges of volumes of liquids so as to improve the speed, efficiency and accuracy of the volumes delivered in the process. Examples of commercially available liquid handling equipment include, without limitation, the Freedom EVO series by Tecan Trading AG, Mannedorf, Switzerland, the Microlab VANTAGE System by Hamilton Company, Reno, NV, and JANUS by PerkinElmer, Waltham, MA. Including workstation series.

The advantages of automated liquid handling processes are to increase process throughput and efficiency, and to eliminate human error. This advantage depends on the precision and reproducibility of the pipetting process to ensure the integrity of experimental results in the fields mentioned above.

In order to obtain good performance, the control parameters of liquid handling equipment need to be adjusted for specific types of liquids. The control parameters may be many, including, for example, the speed of pump actuation, the volume actuated by the pump, the depth of the probe immersed in the liquid, the delay in removing the probe from the liquid, the speed at which the probe is removed from the liquid. .

The liquid handling equipment may have default control parameters. This control parameter is useful for dispensing water or aqueous solutions with properties similar to water. On the other hand, if the instrument is to be used with liquids that have substantially different properties than aqueous solutions, the control parameters will need to be calibrated and adjusted to ensure correct dispensing of the liquid. Calibration of new control parameters is a time consuming and complex process and is generally performed by an expert. Also, when an automated dispensing procedure is created, the user of the instrument must define a set of control parameters associated with the dispensed liquid. When control parameters are chosen incorrectly, the accuracy of the resulting dispensing process fails to meet required specifications.

These demands exist as obstacles to the use of more advanced liquid handling equipment for the average researcher. That is, calibration of new control parameters for a particular liquid requires time and specialized training. Also, liquid handling process programs require training and experience. Therefore, there is a need to simplify the user experience of automated liquid handling equipment for determining and selecting control parameters.

Patents related to this background art include:

US Pat. No. 8,357,544 entitled "Method for Selecting Dispensing Parameters for Liquids" describes a liquid-based liquid handler. The liquid handler can measure pressure during aspiration and produce a pressure curve from the measurements. Another aspect of U.S. Pat. No. 8,357,544 compares the measured pressure curve to a known pressure curve, and dispense parameters (e.g., , plunger speed).

US Pat. No. 7,694,591, entitled "Method and Apparatus for Evaluating Dosing Processes," describes a syringe and air-based liquid handler. The syringe and air-based liquid handler measures pressure during aspiration/dispensing and detects error when the signal differs from known and expected values, and further measures a predetermined error. can be confirmed.

U.S. Pat. No. 6,938,504, entitled "Method and Apparatus for Evaluating Liquid Dosing Processes," provides examples of measuring pressure during aspiration or dispensing, and measuring the pressure to assess error. Examples are given for comparing predetermined setpoint ranges for a liquid and a set of control parameters.

U.S. Pat. No. 6,662,122, entitled "Method for Controlled Distribution of Liquid During Changing Position of Gas Cushion," provides examples of measuring pressure and time during aspiration and dispensing, as well as dispensing. An example is described that uses a known volume of gas in a dispensing system along with parameters of pump actuation to time a step and compare that time to an expected time.

US Pat. No. 7,197,948, entitled "Method of Dosing a Volume of Liquid and Apparatus for Carrying Out the Method," describes a process that includes actuation of a pump during aspiration. Also, dispensing is controlled to provide and maintain a specific actuation pressure. The flow of liquid towards the pipette tip is measured during this process by calculations based on the magnitude of the pressure. When the desired volume is obtained, the pump operates to reduce this operating pressure. Dispensing parameters are determined based on aspiration results.

U.S. Pat. No. 8,096,197, entitled "Air Variation Liquid Delivery System and Related Method," discloses moving the plunger beyond a set point to maintain a greater flow rate and to force the plunger to the set point. It describes the process of measuring the pressure inside and outside the pipette tip so as to improve the speed of viscous dispensing by returning. US Pat. No. 8,096,197 also describes measuring the volume of liquid in the tip over time based on pressure.

U.S. Pat. No. 7,634,367, entitled "Methods for estimating fluid properties to improve accuracy and sensitivity/specificity of liquids measured in failure mode detection, and methods of use thereof," discloses that during aspiration, pressure and extracting features from the detected data to estimate viscosity. US Pat. No. 7,634,367 adjusts control parameters to improve accuracy based on a set viscosity. A calibration curve is formed using liquids of different known viscosities. The viscosity of unknown liquids can be found by fitting/characterizing pressure curves to known viscosities. The required volume size associated with the aspiration and extraction steps can be modified based on the detected viscosity.

US Pat. No. 8,307,697 entitled "Method for Estimating Viscosity" describes a particular method for estimating viscosity during aspiration. The method includes comparing the pressure change between immediately before aspiration and immediately after plunger movement to the pressure change between immediately after plunger movement and a predetermined time after plunger movement. In particular, US Pat. No. 8,307,697 measures the rate of pressure change during plunger movement. Also, the rate of pressure change changes after plunger movement. Additionally, US Pat. No. 8,307,697 measures pressure a predetermined time after the plunger stops moving. Based on measurements and calculations, viscosity is estimated based on system calibration. Also, the equation is calibrated to determine the actual viscosity based on pressure magnitude.

In one aspect, an apparatus for automated liquid transfer optimized dispensing is disclosed. In some embodiments, an apparatus for automated liquid transfer optimized dispensing comprises a pump and a pipette tip in fluid communication with the pump. The pipette tip has a conduit containing an operating air pressure that is related to atmospheric pressure. This working air pressure has an upper limit. The device includes a pressure sensor in communication with the conduit. The pressure sensor is configured to measure working air pressure, atmospheric pressure, and changes in working air pressure caused by aspirating or dispensing liquid with a pipette tip. The apparatus includes a controller in electrical communication with the pump and the pressure sensor. The control receives input from a pressure sensor and directs the speed of the pump to keep the operating atmospheric pressure below an upper limit by adjusting the speed of the pump during aspiration or dispensing of liquid with a pipette tip.

In some embodiments, the devices described herein comprise a frame and an actuator fixed to the frame and in electrical communication with a controller. An actuator is operatively connected to the pump and the pipette tip and configured to control operation of the pump, the pipette tip, or both the pump and the pipette tip.

In some cases, the pumps described herein include a motor and a syringe in operative connection with the motor.

In another aspect, a method of automated liquid transfer optimized dispensing is disclosed. In some embodiments, a method of automated liquid transfer optimized dispensing comprises the steps of providing an apparatus for automated liquid transfer optimized dispensing as described herein; aspirating or dispensing; adjusting the speed of the pump to limit the working air pressure in the conduit of the pipette tip to a pressure level less than or equal to the maximum working air pressure during aspiration or dispensing of the liquid; and actuating the pump to change the volume of air in the air. The volume of air depends on the desired volume of liquid to be aspirated or dispensed. In some embodiments, the methods described herein comprise providing a container holding liquid. This liquid has unknown physical properties. The method also includes inserting the pipette tip into the liquid for aspiration or dispensing. In some cases, the methods described herein may comprise establishing a reference pressure within the conduit. This reference pressure is the pressure in the conduit while there is no liquid in the conduit. In another embodiment, the methods described herein may comprise measuring pressure within the conduit with a pressure sensor. In some cases, the reference pressure is equal to the atmospheric pressure inside and outside the conduit. In some cases, aspirating or dispensing the liquid comprises activating a pump.

The methods described herein may comprise filtering the pressure sensor measurements by calculating a behavioral average of the pressure sensor signals. A behavioral average , as described herein, may be established by calculating the average of all measurements within a given time period.

In some cases, the controls described herein may adjust the speed of the pump while operating to keep the working air pressure in the conduit at or below the maximum working air pressure.

In some embodiments, the methods described herein comprise confirming a steady-state pressure response within the conduit after the pump is actuated to change the volume of air within the conduit. good too. In some cases, confirming the steady-state pressure response comprises measuring the slope of the pressure response over time. In some cases, the slope is calculated by dividing the difference in pressure before and after a given time interval by the magnitude of the time interval using the formula of Equation 1 below.

s is the slope (temporal rate of change) of the pressure response. n is the number of time intervals that have elapsed since the beginning of the slope measurement. P is the pressure. _ts is the time interval of the slope.

In some embodiments, the pumps described herein may comprise a syringe and a piston. Actuating the pump comprises moving the piston outward from the syringe during aspiration and moving the piston toward the syringe during dispensing. In some cases, actuating the pump may occur at a sufficient rate to produce a substantially measurable change in pressure within the conduit.

Ｐ_τは作動空気圧である。Ｐ_０は参照圧力である。Ｐ_１は、ピストンの動作の終了時、及び指数関数的減衰の開始時の圧力である。一部の実施形態において、本明細書に記載されている方法は、作動空気圧がＰ_τの値に達するまで減衰するとき、作動空気圧を連続的に測定するステップを備えてもよい。 The operating air pressures described herein can be calculated by Equation 2 below after a period of exponential decay of the time constant.

P _τ is the working air pressure. P ₀ is the reference pressure. _P1 is the pressure at the end of the piston's motion and the beginning of the exponential decay. In some embodiments, the methods described herein may comprise continuously measuring the operating air pressure as it decays until it reaches a value of _Pτ .

In some embodiments, termination of pump actuation is accompanied by a reduction in pump speed that serves as a step input to produce a substantially measurable first order response to actuation air pressure.

ｔ_ｆはフィルタリングを行う行動平均の時間窓である。ｔ_ｓは勾配設定の時間窓である。ｓ_０は定常状態に対する勾配の閾値である。ｃ_１，ｃ_２，ｃ_３，ｃ_４，ｃ_５，ｃ_６は、分注システムの形状に固有の実験的に定まる係数である。 In some embodiments, the methods described herein may comprise determining parameters for adapting the liquid to the dispensing device. This parameter can be calculated by Equation 3 below.

t _f is the time window of the behavioral average for filtering. _ts is the time window for slope setting. s ₀ is the slope threshold for steady state. c ₁ , c ₂ , c ₃ , c ₄ , c ₅ , c ₆ are experimentally determined coefficients specific to the dispensing system geometry.

In order to describe the disclosed subject matter in general terms, reference is made to the accompanying drawings. This accompanying drawing need not be to exact scale.
FIG. 1 is a block diagram of an embodiment of liquid handling equipment that may be used to perform the method of automated liquid transfer optimized dispensing of the present invention. FIG. 2 shows a side view of an embodiment of the liquid handling instrument of FIG. 1 that can be used to perform the method of automated liquid transfer optimized dispensing of the present invention. FIG. 3A shows a graph of an example of signals measured during aspiration of an aqueous solution using the automated liquid transfer optimized dispensing method of the present invention. FIG. 3B shows a graph of an example system response during aspiration of an aqueous solution using the automated liquid transfer optimized dispensing method of the present invention. FIG. 4 shows an example graph of measured signal and system response during aspiration of 100% glycerol using the automated liquid transfer optimized dispensing method of the present invention. FIG. 5 shows a flow chart of an embodiment of a general method for automated liquid transfer optimized dispensing using the liquid handling device of the present invention. FIG. 6 shows a flowchart of a particular method embodiment of automated liquid transfer optimized dispensing using the liquid handling device of the present invention.

The subject matter of the invention is described below with reference to the accompanying drawings. In the accompanying drawings some, but not all embodiments of the present subject matter are shown. Like numbers refer to like elements throughout. The inventive subject matter may be embodied in many different forms and should not be construed as limited to the embodiments below. Rather, these embodiments are provided so that this invention will satisfy applicable legal requirements. Indeed, many modifications and other embodiments of the present subject matter will occur to those skilled in the art. The subject matter of the present invention pertains to those skilled in the art and has the benefit of the teachings presented in the foregoing description and accompanying drawings. It is therefore understood that the subject matter of the present invention is not limited to the particular embodiment and that modifications and other embodiments are included within the scope of the appended claims.

In some embodiments, the present subject matter provides an apparatus and method for automated liquid transfer optimized dispensing. The apparatus and method for automated liquid transfer optimization of the present invention can transfer liquids regardless of the properties of the liquid and without prior knowledge of the properties of the liquid. The apparatus and method for automated liquid transfer optimization of the present invention relates to automating certain aspects of the liquid transfer process for automated liquid handling equipment to simplify the experience of the user of this equipment. Compared to conventional automated liquid handling equipment, the automated liquid transfer optimization apparatus and method of the present invention are characterized by (1) the need to define liquid properties when programming automated liquid handling; 2) provide a means of reducing or completely eliminating the need to calibrate dispensing parameters for each specific liquid being processed;

In some embodiments, the automated liquid transfer optimized pipetting apparatus and methods of the present invention provide automatic liquid It can be used to enhance the user's experience of processing equipment. For example, a device and method for automated liquid transfer optimized dispensing can be used to avoid detailed calibration of dispensing parameters for different liquid properties. Thus, automated liquid handling equipment correctly performs the dispensing process without prior knowledge of the properties of the dispensed liquid.

In the prior art, the control parameters of automatic liquid handling equipment have to be specifically calibrated for each dispensing process according to the properties of the liquid to be transferred. This is a delicate and time consuming process. This step is generally performed by trained professionals. Also, after the control parameters for a particular liquid have been calibrated, the user is required to define the type of liquid to be used at each step of the dispensing procedure when programming automatic liquid handling. This disadvantage and complexity prevents the average researcher from using automated liquid handling for pipetting tasks that are normally performed manually. Thus, in some embodiments, the automated liquid transfer optimized dispensing apparatus and method of the present invention reduces or eliminates these disadvantages, and provides advance knowledge of liquid properties. can be used to achieve accurate and repeatable dispensing without the need for That is, the apparatus and method for automated liquid transfer optimization dispense allows automatic real-time adaptation of control parameters to match any liquid encountered by the system.

FIG. 1 is a block diagram of an embodiment of a liquid handling instrument 1 that may be used to perform the methods of automated liquid transfer optimized dispensing of the present invention. The liquid handling device 1 is a pipetting device and is an embodiment of the automatic liquid transfer optimized pipetting device of the present invention.

Liquid treatment device 1 includes pump 2 in fluid communication with nozzle 3 through conduit 4 . The pump 2 can measure a certain volume and change mechanism. In one embodiment, pump 2 is a syringe pump including syringe 22 driven by motor 21 . In some embodiments, pump 2 may be an air pump that produces a regulated source of positive and/or negative pressure (ie, vacuum). This positive and/or negative pressure can be used to measure volume in conjunction with a flow sensor (not shown) and valve (not shown). In one embodiment, conduit 4 is filled with air. In another embodiment, the conduit 4 is completely or partially filled with a system liquid, such as water. This liquid reduces the volume of air between nozzle 3 and pump 2 .

The nozzle 3 has an opening 32 . Liquid is sucked up through this opening 32 or discharged from the nozzle 3 . In one embodiment the nozzle 3 is fixed to the liquid treatment device 1 . In another embodiment, nozzle 3 may be a removable nozzle, such as a removable and disposable pipette tip. Nozzle 3 is therefore referred to as pipette tip 3 . In some embodiments, liquid handling device 1 includes one or more pressure sensors 9 within conduit 4 . A pressure sensor 9 is used to measure the air pressure and/or liquid pressure in conduit 4 and/or pipette tip 3 . The liquid treatment device 1 includes an electrical control section 7 . This electronic control 7 may contain an optimization algorithm 8 . An electronic controller 7 and/or an optimization algorithm 8 may be used to process information from pressure sensor 9 to control operation of pump 2 (eg, a syringe pump).

A container 6 is also provided for the pipette tip 3 of the liquid handling device 1 . Container 6 holds a large amount of liquid 61 . In the liquid handling instrument 1 the opening 32 of the pipette tip 3 is inserted into the liquid 61 so that the liquid 61 can be aspirated or dispensed.

There is a set of control parameters that govern the execution of a dispensing process (eg aspiration or dispensing) by an automatic liquid handling device such as liquid handling device 1 . The control parameters may include the speed of pumping, the delay between when pumping is completed and when the pipette tip 3 is removed from the liquid 61 and the speed when the pipette tip 3 is removed from the liquid 61 . The control parameters need to be adjusted and optimized to match the properties of the particular liquid to ensure repeatable and error-free dispensing of the liquid. Thus, in some embodiments, the liquid handling device 1 and method of the present invention can adjust dispense control parameters in real-time to maximize dispense performance without prior knowledge of the properties of the liquid 61 to be dispensed. Provide an analysis of the sensor data as you adjust. In particular, the liquid handling instrument 1 and method ensure error-free aspiration and dispensing during the liquid handling process, and to predict the time when the process is completed, the pipette tip (e.g., pipette tip 3). pneumatic system response of .

The liquid handling device 1 and method of the present invention are capable of detecting predetermined errors that indicate failure of the dispensing process. With minimal training, users who have no experience in programming liquid handlers for specific liquids in the laboratory can easily and intuitively program automated liquid handlers incorporating the algorithms of the present invention. can handle. That is, a user who has no experience in programming a liquid handler for a particular liquid can, with a minimum of training, program the liquid handler of the present invention into which the algorithm of the present invention (eg, optimization algorithm 8) is incorporated. 1 and methods can be handled easily and intuitively.

FIG. 2 shows a side view of an embodiment of the liquid handling device 1 of FIG. 1 that can be used to perform the method of automated liquid transfer optimized dispensing of the present invention. As shown, the liquid handling instrument 1 includes, without limitation, a pump 2, a pipette tip 3 as described above in sealing connection with a conduit 4 leading to the pump 2 (in FIG. 1), an electrical control 7, an optimal It includes an algorithm 8, a pressure sensor 9, and a vertical linear actuator 5 that can move the pump 2 and pipette assembly vertically.

In particular, FIG. 2 shows details of an embodiment of pump 2 . That is, in some embodiments, the pump 2 may be a syringe pump. The syringe pump includes, without limitation, motor 21 driving lead screw 24 , linear motion guide 23 and syringe 22 . Vertical linear actuator 5 may include, without limitation, actuator motor 51 driving actuator lead screw 53 , actuator linear motion guide 52 , and all elements attached to fixed frame 54 of liquid treatment equipment 1 .

The liquid treatment equipment 1 of FIG. 2 can be connected with an electric control unit 7 as shown in FIG. For example, the electrical controller 7 may be a general purpose computer, special purpose computer, personal computer, microprocessor, or other programmable data processing device. The electrical control 7 serves to provide processing power to store, interpret and/or execute software instructions and control of the overall process of the liquid treatment appliance 1 . The electrical control unit 7 and/or the optimization algorithm 8 may, without limitation, generate signals, receive signals, process signals, transmit operational commands, and/or perform the electrical functions described above and other functions. or can process information or data.

An air change dispensing device, such as the liquid handling device 1 of FIGS. 1 and 2, can be theoretically modeled as a second order system comprising mass, volume and resistance. A second order system includes two energy storage elements in the form of springs, such as capacitance and mass inertia, and can be modeled by second order differential equations. The response of a secondary system is an event that is understood while depending on the properties of the components in the system. For example, a secondary electrical system may include inductors, capacitors, and resistors. In this system, energy can be stored in capacitors and inductors. In pipetting devices, "mass" refers to the volume of liquid in the pipette tip. Also, "volume" refers to the volume of compressible air between the liquid in the pipette tip and the pump. Furthermore, “resistance” refers to the restricted flow of liquid through the opening 32 of the pipette tip 3 . This device can store energy in two modes: (1) the capacity of the compressible volume of air, and (2) the inertia of the liquid.

3A, 3B, and 4 are graphs of examples of pressure responses measured during aspiration of liquid using an apparatus (e.g., liquid handling device 1) and method for automated liquid transfer optimized dispensing of the present invention. be. FIG. 3A shows a graph 300 of pressure response measured during aspiration of water. FIG. 3B also shows a graph 310 of the measured pressure response during water aspiration. Further, FIG. 4 shows a graph 400 of pressure response measured during aspiration of 100% glycerol.

With reference to graph 300 of FIG. 3A and graph 400 of FIG. 4, some aspects of the apparatus (eg, liquid handling device 1) and methods for automated liquid transfer optimized dispensing of the present invention are described. Graph 310 of FIG. 3B is described in detail below. In FIG. 3A, a graph 300 shows the pressure response 800 of the enclosed volume of air while the device is in operation. After the actuation of syringe pump 2 to the desired volume is complete, pressure response 800 exhibits exponential decay 801 as it returns to steady state 802 . In particular, the pressure response 800 settles into a steady state 802 without significant oscillations around the steady state. This result indicates that the liquid-handling device 1 is an overdamped second-order system, and that the effects of inertial mass (e.g., the momentum of the liquid moving in and out of the pipette tip 3) are significantly higher than those of resistance and volume. Indicates that it can be ignored. Thus, the liquid handling device 1 includes capacity and resistance in the form of a volume of compressible air between the liquid 61 at the pipette tip 3 and the restricted flow of liquid through the opening 32 of the pipette tip 3. It can be modeled more simply as a first order system. The actuation of pump 2 can be considered an input to the primary system.

For the purposes of the methods described herein, the aspiration or dispensing of liquid performed by this device (ie liquid handling device 1 in FIGS. 1 and 2) can be divided into two stages. During the first stage, pump 2 operates to change the volume of air in pipette tip 3 . This volume of air depends on the desired volume of liquid 61 to move in and out of the pipette tip 3 . Due to the compressibility of the air in conduit 4 , movement of liquid in and out of pipette tip 3 delays pump 2 operation. Thus, when the pump 2 completes operation, the air within the conduit 4 is either in a compressed or expanded state and has stored energy in the form of a pressure or vacuum related to the atmospheric pressure outside the equipment. This keeps the liquid moving in and out of the pipette tip 3 . The second phase then begins when the desired volume pump has been actuated and continues until the air pressure in conduit 4 is in equilibrium with the air pressure outside the device. At this time, the liquid does not move inside or outside the pipette tip 3 . At this time, aspiration or dispensing is completed. Also, the pipette tip 3 can be removed from the liquid 61 .

During the dispensing process, the pressure or vacuum of the enclosed air volume within the device relative to the atmospheric pressure outside the system is referred to as the "actuating air pressure". In the case of a vacuum inside the system relative to the outside of the system, the working air pressure is defined as "negative working air pressure" during aspiration. In the case of an increased vacuum in the system relative to the outside of the system, the operating air pressure is defined as "positive operating air pressure" during dispensing.

During the first phase of the dispensing process, pump 2 is activated. The change in operating air pressure also increases the volume of air in conduit 4 . If the actuation air pressure is allowed to increase too much, errors can occur resulting in inaccurate dispensed volumes. During aspiration, the negative working air pressure can be so large that the pressure in the pipette tip 3 falls below the vapor pressure of the liquid 61 to be aspirated. This causes the liquid 61 to evaporate and generate air bubbles inside the pipette tip 3 . This type of error is called "cavitation" and reduces the accuracy of the transferred volume. During dispensing, the liquid 61 in the pipette tip 3 can smoothly and coherently flow out of the pipette tip 3 . If the positive actuation air pressure becomes too great, the liquid 61 in the middle of the pipette tip 3 can flow faster than the liquid lining the inner wall of the pipette tip 3 . This causes the pressurized air in the liquid handling device 1 to avoid the pipette tip 3 than the desired volume of liquid. This type of error is called "tunneling" and reduces the accuracy of the transferred volume.

Some methods of the present invention accumulate in volume by limiting the operating air pressure in conduit 4, as measured by pressure sensor 9, during pump operation during the first phase of the dispensing process. Associated with limiting energy. This prevents dispensing errors. By limiting the working air pressure of the volume of air in conduit 4 during the first stage of the dispensing process, cavitation or tunneling can be prevented regardless of the properties of liquid 61 being aspirated or dispensed. The operating air pressure can be limited by adjusting the speed of pump actuation during the first stage of the dispensing process.

Part of the method of the present invention involves predicting and verifying the correct time for the working air pressure to come into equilibrium with the atmospheric pressure outside the liquid handling device 1 during the second phase of the dispensing process. . This indicates that no liquid will enter or leave the pipette tip 3 and that the dispensing process is complete. When the pipette tip 3 is removed from the liquid 61 before the working air pressure settles to a steady state, the entire volume of liquid corresponding to the volume actuated by the pump is completely aspirated or dispensed from the pipette tip 3, thus dispensing Volumetric errors can occur. If the pipette tip 3 always remains in the liquid 61 after reaching equilibrium, the pipette tip 3 will reduce the efficiency of the process. Accordingly, the method of the present invention comprises timely confirmation of reaching equilibrium. This allows the execution of the dispensing process to proceed efficiently.

In some embodiments, methods for limiting the actuation air pressure during the first stage of the dispensing process are described below. In one embodiment, referring back to graph 300 of FIG. 3A and graph 400 of FIG. 4, the method herein begins with measuring a reference pressure 803 (P ₀ ) prior to aspiration or dispensing. For example, reference pressure 804 may be the pressure within conduit 4 when no liquid is within conduit 4 . The reference pressure 803 can be measured before and after the pipette tip 3 is lowered towards the liquid 61 while the syringe pump 2 is measured before it is activated. In some embodiments, the reference pressure 803 can be calculated as an average of multiple measurements to filter the effects of noise on the signal.

The method of the present invention proceeds with actuation of pump 2 to vary the volume of air within pipette tip 3 in relation to the desired volume to be aspirated or dispensed. The initial control parameters for pump actuation, such as pump speed, are the same for any dispensing process regardless of the liquid 61 being transferred. Preferably, the default control parameters for pump actuation provide sufficient pump speed to produce a substantially measurable change in actuation air pressure during any dispensing process. In some embodiments, the default control parameters may be based on the volume of liquid to be aspirated or dispensed.

During pump operation, the operating air pressure within the liquid handling device 1 is measured. Less viscous liquids generally have less resistance to flow through opening 32 of pipette tip 3 . Therefore, the operating air pressure cannot be significantly increased when dispensing this liquid during pump actuation. Liquids of greater viscosity tend to have greater resistance to flow through opening 32 of pipette tip 3 . Thus, the operating air pressure can increase during pump actuation to a point that causes dispensing errors. When the actuation air pressure reaches a predetermined threshold 804 (see graph 400) during pump actuation, operation of the pump 2 is delayed to prevent the actuation air pressure from reaching a point where the above-described error can occur, or stop. Operation of the pump 2 is controlled such that the working air pressure does not exceed a predetermined threshold.

In some embodiments, operation of pump 2 may stop completely when the operating air pressure reaches a threshold. When pump 2 stops, for example at pump stop time 805 (see graph 400 ), the operating air pressure begins to decay as liquid moves in and out of pipette tip 3 . Operation of pump 2 may resume when the operating air pressure decays above lower limit 806 (see graph 400). In some cases, operation of pump 2 may be paused and resumed multiple times to complete all necessary pump 2 operations to deliver the desired volume without exceeding the upper operating air pressure limit. The upper and lower values relate to the particular pipetting device and pipette tip 3 geometry and can be determined experimentally.

In one embodiment, the speed of pump 2 is regulated by a control loop. The control loop considers the operating air pressure as an input and the pump speed as an output. In this embodiment, when the operating air pressure reaches the upper limit during pump operation, the speed of pump 2 is adjusted by the control loop to keep the operating air pressure below the upper limit. This control mode allows the dispensing process to be performed faster.

Pump 2 stops when it changes the volume of air required to aspirate or dispense the volume of liquid involved. It is important to note that pump 2 does not operate to change volumes greater than the volume associated with the desired volume of liquid to be aspirated or dispensed.

The second phase of the dispensing process begins when pump 2 has completed actuation to the desired volume, eg at pump actuation completion time 807 . Stopping pumping is a change in input to the primary system, adjusting the input from some positive or negative value to zero. When the pump action stops due to sufficient deceleration, the change in input can be presumed as a step input. The response of a first order system to a step input is characterized by a time constant parameter. This principle can be seen in the consideration of models of signal and energy systems. The time constant is the time that indicates how fast the system responds to changes in the input. The time constant is generally regarded as the time required for the system to reach 63.2% (equal to 1-1/e) of the steady state response after a step input to the system. A time of 5 time constants is taken as the time required for a pure first order system to reach 99.3% of its steady state response. At 99.3% of this steady state response, the system can generally be considered to have reached steady state. Therefore, when the time constant of the first order system response to a step input is determined in real time, the time required for the system to reach steady state can be reasonably predicted. The time constant can be determined in real time if the magnitude of change in system response to a step input is known. The magnitude of the change in system response for a step input from a positive or negative value to 0 is defined as the difference between the system response measured prior to the step input and the known steady-state equilibrium response to the 0 input. obtain.

During the dispensing process, the operating air pressure decays exponentially (ie, exponential decay 801) as it returns to steady state 802 from when the pump 2 stops operating. In some embodiments, the time constant of the pressure response in exponential decay is determined in real time to predict the time required to reach steady state 802 . At this time, the aspiration or dispense is considered complete. This is because the magnitude of the change in actuation air pressure is equal to the measured actuation pressure 803 (P 0 ), measured before the dispense process begins, and using the reference pressure 803 (P ₀ ) measured before the dispensing process begins as an equilibrium value, It is possible because it can be determined by using the air pressure as an initial value for the characteristics of the first order response. By measuring the time constant of this decaying pressure response, the time for the response to settle into steady equilibrium can be estimated. Thus, regardless of the characteristics of the liquid 61 being aspirated or dispensed, the pressure response provides sufficient information to predict when the dispensing process is complete.

For a liquid handling device 1, various factors can adversely affect the exponential decay of the pressure response during the second stage of aspiration or dispensing. The main factors include the properties of the liquid 61 to be aspirated or dispensed, the shape of the dispensing device, and the shape of the pipette tip 3. Some factors may temporarily have small effects that change during the dispensing process, such as the volume of liquid in the pipette tip 3 . Environmental factors external to liquid handling equipment 1, such as temperature, atmospheric pressure, and humidity, can affect the pressure response. A particular consideration of the dispensing system, considered as a primary system, is the residual vacuum 810 of the volume of air enclosed when the liquid is in the pipette tip 3 at steady state 802 . When the liquid is in the pipette tip 3 in a steady state of equilibrium, e.g. after an aspiration step, a slight negative working air pressure (i.e. the vacuum related to the atmospheric pressure outside the pipette tip 3) causes a steady state is in the liquid treatment equipment 1 of . This keeps the liquid 61 within the pipette tip 3 . The magnitude of this residual vacuum depends on the volume of liquid in the pipette tip 3 , the density of the liquid, the shape of the pipette tip 3 and the volume of air inside the liquid handling device 1 . Therefore, the magnitude of the residual vacuum and final steady-state response can vary from step to step.

Ｐ_０はポンプ作動前に測定される参照圧力（参照圧力８０３）である。
Ｐ_１は、ポンプ作動の終了時、及び作動空気圧の指数関数的減衰８０１の開始時に測定される圧力である。 In certain embodiments, due to the particular considerations of the liquid handling device 1, the time constant (τ) is varied from its generally accepted definition to suit the characteristics of the particular dispensing system geometry. In one embodiment, the time constant is defined as the time required for the pressure response to reach 40% of the steady state response. For the purpose of calculating the working air pressure after a time constant, the steady state is taken to be equal to the atmospheric reference pressure measured before the process. In _one embodiment, when the syringe piston completes motion to the desired volume (at pump activation completion time 807), the magnitude of actuation air pressure is recorded as P1. Also, the time is recorded as _t1 . The level of actuation air pressure after a time constant (P _τ ) is calculated by Equation 4 below.

P ₀ is the reference pressure (reference pressure 803) measured prior to pump actuation.
_P1 is the pressure measured at the end of pump actuation and the beginning of the exponential decay 801 of the actuation air pressure.

The working air pressure is continuously measured as it decays (exponential decay 801) until it reaches the value of _Pτ . This time is recorded as t _τ 808 . The time constant τ is calculated as the difference between t ₁ and t _τ by Equation 5 below.

In some embodiments, the step input needs to be varied in conjunction with the setting of the time constant to match the characteristics of the geometry of the particular dispense system, after which multiple passes before steady state. The time of the time constant is reached. Continuing with the above example, in a system according to one embodiment, with a time constant defined at 40% decay to steady state, steady state may be reached after 10 time constant times. The parameters for defining the time constant and the multiple time constants for reaching steady state are tied together and can vary based on the geometry of the system. These parameters can be determined experimentally.

ｓは圧力応答の変化率である。
Ｐは特定の時間間隔において測定される圧力である。
ｎは、圧力応答の変化率の測定の開始から経過した時間間隔の数である。
ｔ_ｓは時間間隔の変化率である。 Due to the multiple effects described above in the system, the pressure response may vary slightly from step to step for the same liquid aspirated with the same control parameters. To overcome this aspect and improve the reliability of the method of the present invention, steady state predictions can be confirmed by measuring the rate of change of the pressure response over time. In one embodiment, the rate of change of pressure response is calculated over a predetermined time interval. The rate of change s is calculated by dividing the difference in pressure before and after each time interval by the magnitude of the time interval, as in Equation 6 below.

s is the rate of change of the pressure response.
P is the pressure measured at a specific time interval.
n is the number of time intervals elapsed since the beginning of the measurement of the rate of change of the pressure response.
_ts is the rate of change of the time interval.

In one embodiment, it can be determined that the system has reached steady state when the rate of change of the pressure response is below a threshold such that the pressure response varies slightly over time. Therefore, according to embodiments of the method of the present invention, two conditions must be fulfilled to ensure completion of the dispensing process. This condition implies that the system must wait a time constant of 10 times after the pumping completion time 807 and that the pressure response will reach the steady state 802 by waiting until the rate of change of the pressure response is below the threshold. You have to make sure that it fits in the FIG. 3B shows the principle. In this principle, curve 850 of graph 310 shows the slope of the operating air pressure calculated by the system during the same 200 μL water aspiration shown in graph 300 of FIG. 3A. Graph 310 of FIG. 3B is synchronized with graph 300 of FIG. characterize. A confirmed end time 802 is determined from measuring this slope when the slope falls below a predetermined threshold. Also, in one embodiment, the measurements from the pressure sensor 9 are filtered by calculating a behavioral average of the pressure sensor's signal. Preferably, pressure measurements from pressure sensor 9 are made continuously at a constant data rate. A behavioral average is defined by calculating the average of previous measurements over a given time window of the current measurement. Preferably, the output of the filtered pressure signal is the value of pressure considered in the rate of change of pressure response calculations described above.

In one embodiment, the parameters described above (e.g., the time window for the behavioral average filter, the time interval for calculating the rate of change of pressure response, and the threshold rate of change of pressure response for ascertaining steady state) are the time constant τ is defined as a function of This allows for optimal system response regardless of the properties of the liquid 61 being aspirated or dispensed. For example, very viscous liquids have relatively large time constants and very large exponential decays associated with them for steady state. Near the end of this decay, the pressure response gradually changes. Therefore, the rate of change needs to be measured over a long period of time to obtain sufficient resolution. By comparison, aqueous solutions have relatively small time constants and settle to steady state very quickly, perhaps faster than the time the rate of change is measured for viscous liquids. If the optimum parameters for aspiration of viscous liquids are used to define the steady state for aspiration of aqueous solutions, the process will not be efficient. If optimal parameters for aspiration of aqueous solutions involving small times over which the rate of change is measured are used to establish steady state for viscous liquids, steady state may be erroneously established too quickly, resulting in inaccurate dispensing. results in

ｔ_ｆは行動平均フィルタの時間窓である。
ｔ_ｓは圧力応答の変化率を定める時間間隔である。
ｓ_０は定常状態に対する圧力応答の変化率の閾値である。
ｃ_１，ｃ_２，ｃ_３，ｃ_４，ｃ_５，ｃ_６は、特定の分注システムの形状に固有の実験的に定まる係数である。 In one embodiment, the above parameters are determined as linear functions of the time constant τ with experimentally determined coefficients. This factor may be calibrated for a particular system geometry and dependent on factors including the volume of air between the pump 2 and pipette tip 3, the size and shape of the pipette tip 3, and parameters of pump actuation. The above parameters are calculated by Equation 7 below.

t _f is the time window of the behavioral average filter.
_ts is the time interval defining the rate of change of the pressure response.
_s0 is the threshold rate of change of the pressure response to steady state.
c ₁ , c ₂ , c ₃ , c ₄ , c ₅ , c ₆ are experimentally determined coefficients specific to a particular dispensing system geometry.

In some embodiments, additional control parameters such as the speed of the pipette tip 3 being removed from the liquid 61 can be derived from the time constant after reaching steady state response, in a manner similar to that described above. Also, in some embodiments, control parameters for the dispensing process may be derived from time constants established during the associated aspiration process.

Referring to FIG. 5, a flow chart of an embodiment of a method 500 for automated liquid transfer optimized dispensing is described using the liquid handling device 1 of the present invention according to a simple configuration. This method 500 can be used to mimic and optimize the way a person operates a manual pipette. This method 500 may include, without limitation, the following steps.

At step 510, an apparatus for automated liquid transfer optimized dispensing is provided. For example, a liquid treatment device 1 as shown in Figures 1 and/or 2 is provided.

In step 515, using the electronic controller 7 and/or the optimization algorithm 8, the pump 2 safely adjusts the operating air pressure without prior knowledge of the liquid's properties as a method of ensuring accurate and error-free dispensing. Controlled to limit within limits.

At step 520, using the electronic controller 7 and/or the optimization algorithm 8, the pump 2 is operated to vary the volume of air required to aspirate or dispense the associated volume of liquid. do.

At step 525, using the electronic controller 7 and/or the optimization algorithm 8, the pressure response within the pipette tip 3 after activation of the pump 2 is treated as the first order system response. That is, the prediction of the end time is performed based on the value of the time constant. The value of this time constant is defined "on the fly". Also, the prediction is confirmed when the rate of change of the pressure response is below a predetermined threshold. Parameters for measuring the rate of change and associated thresholds are defined as a function of the value of the time constant.

Referring to FIG. 6, a flowchart of method 600 describes a particular method of automated liquid transfer optimized dispensing using liquid handling device 1 herein. This method 600 may include, without limitation, the following steps.

At step 610, an apparatus for automated liquid transfer optimized dispensing is provided. For example, a liquid treatment device 1 as shown in Figures 1 and/or 2 is provided.

At step 615, a container of liquid to be treated is provided. Also, the properties of the liquid are unknown. For example, a container 6 holding a quantity of liquid 61 is provided. Also, the physical properties of liquid 61 are unknown.

At step 620, a pipette tip of an automated liquid transfer optimized dispensing device is inserted into a liquid for aspiration or dispensing. For example, under the control of the electronic controller 7 and/or the optimization algorithm 8, the pipette tip 3 of the liquid handling device 1 is inserted into the liquid 61 for aspiration or dispensing.

At step 625, a reference pressure is determined. For example, using electronic controller 7 and/or optimization algorithm 8, a reference pressure is established prior to aspiration or dispensing of liquid 61 . The reference pressure is equal to the atmospheric pressure inside and outside the conduit 4 prior to the aspiration or dispensing process.

At step 630, the pump of the device for automated liquid transfer optimized dispensing is activated to aspirate or dispense liquid. For example, under the control of the electronic controller 7 and/or the optimization algorithm 8, the pump 2 of the liquid handling device 1 is activated for aspiration or dispensing of the liquid 61. In particular, when the pump 2 is a syringe pump, the piston of the syringe pump moves outward (ie away from the pipette tip 3) during aspiration. Also, the piston of the syringe pump moves inwards (ie towards the pipette tip 3) during dispensing. Further, in this step, pumping is performed at a sufficient speed to produce a change in pressure within conduit 4 that is substantially measurable.

At step 635, the pressure response within the conduit is measured. For example, electronic control 7 and/or optimization algorithm 8 are used to measure values from pressure sensor 9 and to measure the pressure response within conduit 4 of liquid treatment device 1 .

At step 640, the operating air pressure of the device for automated liquid transfer optimized dispensing is determined. For example, the electronic control 7 and/or the optimization algorithm 8 are used to determine the operating air pressure of the conduit 4 of the liquid treatment equipment 1 .

At step 645, the operating air pressure is maintained within predetermined limits through control of the speed of operation of the pumps of the automated liquid transfer optimized dispensing system. For example, under the control of the electronic controller 7 and/or the optimization algorithm 8, the working air pressure in the conduit 4 is kept within predetermined limits through control of the speed of operation of the pump 2 of the liquid treatment equipment 1. .

At step 650, pump operation ceases after a change in the volume of air required to aspirate or dispense the associated volume of liquid. For example, under the control of the electronic controller 7 and/or the optimization algorithm 8, operation of the pump 2 causes the pump 2 to adjust the amount of air in the pipette tip 3 according to the desired volume of liquid 61 to be aspirated or dispensed. Stops when the volume changes. Thus, when the pump 2 stops operating, liquid can be aspirated or dispensed until equilibrium (ie steady state) is reached. Also, cessation of pump actuation is effected by a sufficient reduction in the speed of pump 2 to act as a step input to produce a substantially measurable first order response to actuation air pressure.

At step 655, the steady-state pressure response within the conduit of the automated liquid transfer optimized dispense device is ascertained. For example, using the electronic controller 7 and/or the optimization algorithm 8, the steady state pressure response within the conduit 4 of the liquid treatment equipment 1 is ascertained by measuring the slope of the pressure response over time.

Referring again to FIGS. 5 and 6, during the steps of method 500 and/or method 600 of automated liquid transfer optimized dispensing, the liquid transfer process is controlled to ensure an error-free process and for maximum accuracy and efficiency. measured and automatically adjusted by the electronic controller 7 and/or the optimization algorithm 8 to predict and ascertain the time required to complete the process for . This method accounts for the effects of changes caused by environmental conditions, normal differences in liquid properties, and physical distribution of system components by using the rate of change of the pressure response to ascertain steady state conditions at the end of the process. Hard to accept.

In some embodiments, the liquid handling device 1 and methods 500, 600 of the present invention provide automated dispensing by allowing the device to dispense any liquid without prior knowledge of the properties of the liquid. It may simplify the user experience of devices that perform automatic dispensing and lower the barriers to using devices that perform automated pipetting. For example, compared to conventional automated liquid-handling instruments, the liquid-handling instrument 1 and methods 500, 600 of the present invention reduce (1) the need to define liquid properties when programming automated liquid-handling, and (2) It provides a means of reducing or completely eliminating the need to calibrate dispensing parameters for each specific liquid being processed.

In accordance with the long standing patent law treaty, the terms "a" and "predetermined" refer to "one or more" when used in the present invention, including the claims. Thus, for example, reference to "subject" includes multiple subjects unless the context clearly dictates otherwise (eg, multiple subjects, etc.).

Throughout the specification and claims, the term "comprising" is used in a non-exclusive sense, unless the context requires otherwise. Similarly, the term "include" and grammatical variations of "include" are intended to be non-limiting. Thus, describing an item in a list does not exclude other items that may be substituted for or added to the listed item.

For the purposes of this specification and the claims appended hereto, unless otherwise indicated, quantities, sizes, dimensions, ratios, shapes, formulas, parameters, ratios, numbers used in this specification and claims , properties, and other numerical expressions are in all cases modified by the term "about," even if the term "about" is not expressly expressed in conjunction with a value, amount, or range. Accordingly, unless indicated to the contrary, the set of numerical parameters set forth in the following specification and appended claims need not be constrained, but sought to be obtained by the present subject matter. Reflection tolerances, conversion factors, rounding of numbers, measurement errors, etc., and other factors known to those skilled in the art, may be appropriate and/or required to be large or small, depending on the desired properties. For example, when the term "about" refers to a value, in some embodiments ±100%, ±50%, ±20%, ±10%, ±5%, ±1 %, ±0.5%, ±0.1%. This variation is therefore suitable for performing the method or using the composition of the invention.

Also, the term "about," when used in reference to one or more numbers or a range of numbers, is understood to include and refer to all numbers within the range and to bounds greater or less than the numerical value. Adjust the range by widening the . The recitation of numerical ranges by endpoints includes all numbers subsumed within the range, such as all integers, and also recitations of fractional numbers (such as 1, 2, 3, 4, 5 from 1 to 5, including 1, 2, 3, 4, 5, and for example , 1.5, 2.25, 3.75, 4.1, etc.), and also includes any range within such ranges.

While the above subject matter has been described in detail with figures and examples for clarity, it will be appreciated by those skilled in the art that certain changes and modifications may be practiced within the scope of the appended claims.

Claims (21)

An apparatus for automated liquid transfer optimized dispensing, comprising:
a pump ;
a pipette tip in fluid communication with the pump;
the pipette tip comprises a conduit containing working air pressure ;
the operating air pressure in the conduit is related to the atmospheric pressure outside the conduit;
the working air pressure has an upper limit and a lower limit;
The device comprises:
a pressure sensor in communication with the conduit;
the pressure sensor is configured to measure the working air pressure, the atmospheric pressure outside the conduit , and changes in the working air pressure caused by aspirating or dispensing liquid with the pipette tip;
The device comprises:
a controller in electrical communication with the pump and the pressure sensor;
The control unit
receiving input from the pressure sensor;
indicating the speed of said pump,
adjusting the speed of the pump to maintain the operating air pressure below or above the upper limit during aspiration and dispensing of unknown liquids with the pipette tip;
The device comprises:
a vertical linear actuator fixed to the frame and in electrical communication with the controller;
said vertical linear actuator is operatively connected to a pump and pipette tip and is operatively connected to an actuator motor for moving said device vertically along an actuator lead screw;
A device characterized by: The pump is
motor,
a second lead screw;
a linear motion guide in operative connection with said control;
and a syringe in operative connection with said motor. A method for automated liquid transfer optimized dispensing, comprising:
providing a device according to claim 1;
aspirating or dispensing the liquid in the conduit of the pipette tip;
adjusting the speed of the pump to limit the working air pressure in the conduit of the pipette tip to a pressure level below a maximum air pressure maximum threshold or above a minimum threshold of the maximum air pressure during aspiration or dispensing of the liquid; When,
actuating the pump to change the volume of air in the conduit;
A method, characterized in that the volume of air depends on the desired volume of the liquid to be aspirated or dispensed. The method includes:
providing a container holding said liquid ;
and inserting said pipette tip into said liquid for aspiration or dispensing. The method comprises establishing a reference pressure within the conduit,
4. The method of claim 3 , wherein said reference pressure is the pressure within said conduit while no liquid is within said conduit. 6. The method of claim 5 , wherein said reference pressure is equal to atmospheric pressure inside said conduit and outside said conduit. 4. The method of claim 3 , wherein the step of aspirating or dispensing the liquid comprises activating the pump. 4. The method of claim 3 , comprising measuring pressure within the conduit with the pressure sensor. 9. The method of claim 8 , comprising filtering the pressure sensor measurements by calculating a behavioral average of the pressure sensor signal. 10. The method of claim 9 , wherein the behavioral average is determined by calculating the average of all measurements within a predetermined time period. 4. The method of claim 3 , wherein said control adjusts said speed of said pump while operating to maintain said operating air pressure in said conduit at a pressure below said maximum operating air pressure. 4. The method of claim 3 , wherein the method comprises identifying a steady-state pressure response within the conduit after the pump is operated to change the volume of air within the conduit. 13. The method of claim 12 , wherein confirming the steady-state pressure response comprises measuring a slope of the pressure response over time. The slope is calculated by dividing the difference in pressure before and after a given time interval by the magnitude of the time interval using the formula of Equation 1 below:
s is the slope (temporal rate of change) of the pressure response;
n is the number of said time intervals that have elapsed since the beginning of the slope measurement;
P is the pressure,
14. The method of claim 13 , wherein _ts is the time interval of the slope.

said pump comprising a syringe and a piston,
The step of activating the pump comprises:
moving the piston outward from the syringe during aspiration;
and moving the piston toward the syringe during dispensing . 4. The method of claim 3 , wherein actuating the pump occurs at a rate sufficient to produce a substantially measurable change in pressure within the conduit. The working air pressure, after a period of exponential decay with a time constant, is calculated by Equation 2 below:
P _τ is the working air pressure;
P ₀ is the reference pressure,
4. Method according to claim 3 _, characterized in that P1 is the pressure at the end of the movement of the piston and the beginning of the exponential decay.

18. The method of claim 17 , comprising continuously measuring the operating air pressure as the operating air pressure decays until it reaches a value of P[ _tau ]. 4. The claim characterized in that the termination of actuation of said pump is accompanied by a reduction in speed of said pump which serves as a step input to produce a substantially measurable first order response to said actuation air pressure. 3 ways. 4. A method according to claim 3 , comprising the step of determining parameters for adapting the liquid to the device for dispensing. The parameters are calculated by the following Equations 3 and 4 ,
t _f is the time window of the filtering behavioral average ,
t _s is the time window for slope setting,
s ₀ is the slope threshold for steady state,
21. _The method of claim 20 _, wherein c1 _, c2, _c3 , _c4 , c5, _c6 are experimentally determined coefficients specific to the geometry of the dispensing system.