Sample analyzer, liquid path system, and liquid level detection method

Abstract

The present invention discloses a sample analyzer and its fluid circuit system. The sample analyzer includes a metal needle for adding samples and / or reagents. The metal needle is configured to change its electrical properties when it contacts the liquid surface. The metal needle is connected to a pipeline that transports a cleaning fluid. The analyzer also includes a grounding conductor and a liquid level detection circuit. At least a portion of the conductor contacts the liquid flowing through the pipeline, thereby grounding the cleaning fluid. The input end of the liquid level detection circuit is electrically connected to the metal needle to monitor changes in the metal needle's electrical properties and determine whether the metal needle has contacted the liquid surface based on these changes. By grounding the cleaning fluid, the present invention prevents the cleaning fluid from introducing interference from other links into the metal needle, thereby improving the accuracy of liquid level detection.

Description

Technical Field

[0001] The present invention relates to a sample analyzer, and in particular to a liquid level detection technology in the sample analyzer. Background Art

[0002] Sample analyzers are used to perform in vitro analysis of biological fluids (such as blood) to produce diagnostic results. The analysis process typically includes adding a sample, adding reagents, reacting the sample and reagents to produce a reaction solution, testing the reaction solution, and calculating and analyzing the test results to produce the analytical result. Some analyzers utilize a needle-assisted aspiration and discharge technique during the sample and reagent addition process. For example, the specific process involves the needle being lowered into the sample container below the liquid level. Upon contact with the liquid surface, the needle aspirates a set amount of sample. After aspiration, the needle ascends and moves above the reaction container, discharging a predetermined amount of sample into the reaction container, where the sample reacts with the added reagents. To detect whether the needle touches the liquid surface after descending into the sample container, sample analyzers employ liquid level detection technology. Liquid level detection technologies can be categorized by principle, including capacitance detection, radio frequency detection, ultrasonic detection, and pressure detection. Capacitive detection is currently the most widely used principle. Capacitive level detection can be further categorized into two approaches: using a conductive tip or a metal needle as the probe material. Among them, the metal needle solution is widely used due to its advantages such as low cost.

[0003] Metal needles usually adopt a double-tube structure, such as Figure 1 As shown, a capacitive effect is generated between the inner sleeve 1 and the outer sleeve 2, which can be equivalent to a capacitor. The cavity of the inner sleeve 1 of the metal needle is connected to the driving component 5 through the pipe 3. The driving component operates to change the fluid pressure in the pipe, thereby realizing the liquid suction and discharge functions of the metal needle. When the metal needle contacts the liquid surface, the equivalent capacitance value between the double-layer tubes of the metal needle will change due to the conductive effect of the liquid. If the metal needle is connected to the liquid level detection circuit, the capacitance signal of the metal needle can be detected by the liquid level detection circuit. By monitoring the capacitance signal, it can be determined whether the metal needle has contacted the liquid surface.

[0004] During the detection process, a cleaning fluid typically resides in pipe 3. This fluid is discharged from the metal needle to dilute the sample and clean the metal needle, container, or piping that the sample contacts, thereby preventing cross-contamination between previous and subsequent samples. Furthermore, by filling the metal needle with cleaning fluid, air inside the needle is expelled to facilitate liquid aspiration. When the cleaning fluid is a conductive liquid, even though the piping containing the cleaning fluid is made of insulating material, contact with the metal needle can introduce interference from any link in the cleaning fluid pipeline to the metal needle, thereby inactivating or reducing the metal needle's liquid level detection function.

[0005] To address the impact of interference introduced by pipeline liquid on the metal needle for liquid aspiration, one solution is to isolate the liquid and the metal needle. However, this solution is costly, complex in process, and difficult to control in terms of consistency. It can also easily lead to a dead zone where the liquid and the needle are isolated, causing a series of problems such as cross-contamination. Another solution is to not isolate the liquid and the metal needle, but to filter out the interference introduced by the conductive liquid in the pipeline through circuit filtering. There are many ways to filter circuits, such as using a bridge circuit for filtering. However, these solutions have high cost, complex algorithms, poor reliability, and the filtering effect is easily affected by circuit differences. It can also easily affect the normal liquid level detection function. Summary of the Invention

[0006] The main technical problem solved by the present invention is how to reduce the influence of interference introduced by pipeline liquid on the liquid-absorbing metal needle.

[0007] According to a first aspect, an embodiment provides a sample analyzer, comprising:

[0008] a metal needle, the metal needle being used for adding a sample and / or a reagent and being configured to change its own electrical properties when it contacts a liquid surface;

[0009] A needle moving mechanism, used for supporting the metal needle and driving the metal needle to move;

[0010] Drive components for providing power;

[0011] A pipeline for transporting a cleaning liquid, one end of the pipeline being connected to a metal needle and the other end being connected to a driving component, so that the driving component changes the flow direction of the cleaning liquid in the pipeline, causing the metal needle to absorb or discharge liquid. Depending on the application, the metal needle may absorb or discharge a sample, a reagent, a cleaning liquid, or a diluent;

[0012] a conductor, at least a portion of which is in contact with the liquid flowing through the pipeline, and the conductor is further connected to ground;

[0013] A liquid level detection circuit, wherein the input end of the liquid level detection circuit is used to be electrically connected to the metal needle, for monitoring the changes in the electrical characteristics of the metal needle, and judging whether the metal needle contacts the liquid surface according to the changes in the electrical characteristics of the metal needle.

[0014] According to a second aspect, an embodiment provides a sample analyzer, comprising:

[0015] A pipeline for transporting cleaning liquid, the pipeline being connected to the metal needle, and causing the metal needle to absorb or discharge the liquid by changing the flow direction of the cleaning liquid in the pipeline;

[0016] a conductor, at least a portion of which is in contact with the liquid flowing through the pipeline, and the conductor is further connected to ground;

[0017] A liquid level detection circuit, wherein the input end of the liquid level detection circuit is used to be electrically connected to the metal needle, for monitoring the changes in the electrical characteristics of the metal needle, and judging whether the metal needle contacts the liquid surface according to the changes in the electrical characteristics of the metal needle.

[0018] According to a third aspect, an embodiment provides a fluid path system of a sample analyzer, comprising:

[0019] A pipeline for transporting cleaning fluid, one end of the pipeline being connected to the metal needle and the other end being connected to the driving component, so that the driving component changes the flow direction of the fluid in the pipeline, causing the metal needle to absorb or discharge the liquid. The pipeline includes a separate first pipeline and a second pipeline, the first pipeline and the second pipeline being connected to the metal needle and the driving component, respectively;

[0020] The conductor includes a metal two-way joint and a grounding component. The two-way joint is connected between the first pipeline and the second pipeline, and together with the pipeline forms a channel for liquid circulation. One end of the grounding component is fixedly connected to the two-way joint, and the other end is used to be connected to the ground.

[0021] According to a fourth aspect, an embodiment provides a liquid level detection method, comprising:

[0022] Drive the cleaning fluid to fill the pipe and metal needle;

[0023] Ground the cleaning fluid in the tubing and metal needle;

[0024] The metal needle is driven downward to approach the liquid surface to be sucked, and the electrical characteristic value output by the metal needle is detected in real time during the downward movement of the metal needle;

[0025] Whether the metal needle touches the liquid surface is determined based on the change in the electrical characteristic value.

[0026] In the embodiment of the present invention, the cleaning liquid is grounded to prevent the cleaning liquid from introducing interference from other links to the metal needle, thereby improving the accuracy of liquid level detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 Schematic diagram of the structure of the sampling needle;

[0028] Figure 2 It is a functional module diagram of a sample analyzer;

[0029] Figure 3 A schematic diagram of the layout of components of a sample analyzer according to an embodiment;

[0030] Figure 4A schematic diagram of grounding a cleaning liquid in one embodiment of the present invention;

[0031] Figure 5a A circuit diagram of a phase-locked loop in a liquid level detection circuit in one embodiment;

[0032] Figure 5b Schematic diagram of the equivalent resistance introduced by the ground conductor and the equivalent capacitance shunting of the sampling needle;

[0033] Figure 6 Schematic diagram of the equivalent resistance analysis introduced by the grounding conductor in one embodiment Figure 1 ;

[0034] Figure 7 Schematic diagram of the equivalent resistance analysis introduced by the grounding conductor in one embodiment Figure 2 ;

[0035] Figure 8a This is the waveform diagram of liquid level detection when the cleaning fluid is not grounded;

[0036] Figure 8b This is a waveform diagram of liquid level detection when the cleaning liquid is grounded using the solution of the present invention;

[0037] Figure 9 A schematic diagram of a conductor structure and a grounding process in an embodiment;

[0038] Figure 10 A schematic diagram of a conductor structure and a grounding process in another embodiment;

[0039] Figure 11 is a block diagram of a liquid level detection circuit according to an embodiment;

[0040] Figure 12 A liquid level detection circuit diagram incorporating a calibration circuit in one embodiment. DETAILED DESCRIPTION

[0041] The present invention will be further described in detail below by means of specific embodiments in conjunction with the accompanying drawings. Similar elements in different embodiments are numbered with associated similar elements. In the following embodiments, many detailed descriptions are provided to enable the present application to be better understood. However, those skilled in the art will readily appreciate that some of the features may be omitted in different circumstances, or may be replaced by other elements, materials, or methods. In some cases, some operations related to the present application are not shown or described in the specification. This is to avoid the core portion of the present application being overwhelmed by excessive descriptions, and for those skilled in the art, it is not necessary to describe these related operations in detail. They will fully understand the related operations based on the description in the specification and the general technical knowledge in the art.

[0042] In addition, the features, operations, or characteristics described in the specification may be combined in any appropriate manner to form various embodiments. Furthermore, the steps or actions in the method description may be reordered or adjusted in a manner readily apparent to those skilled in the art. Therefore, the various sequences in the specification and drawings are provided solely for the purpose of clearly describing a particular embodiment and are not intended to be mandatory, unless otherwise specified.

[0043] The serial numbers assigned to components herein, such as "first," "second," etc., are used solely to distinguish the objects being described and do not convey any sequential or technical meaning. References to "connection" and "coupling" herein, unless otherwise specified, include both direct and indirect connections (couplings).

[0044] In the present application, the liquid absorbed and discharged by the metal needle can be a sample or a reagent. The metal needle can also be collectively referred to as a sampling needle, including a sample needle and a reagent needle.

[0045] Some embodiments of the present invention disclose a sample analysis device, please refer to Figure 2 In one embodiment, the sample analysis device may include a sample component 10, a reagent component 20, a measurement component 30, and a control and data processing module 40. In some embodiments, the sample analysis device may further include a display component 50, a signal processing circuit 60, and a fluidic system 70. This will be described in detail below.

[0046] The sample component 10 is used to carry the sample to be tested and to absorb the sample and then provide it to the measuring component 30. Figure 3 In some embodiments, the sample component 10 may include a sample carrying component 11 and a sample dispensing mechanism 12. The sample carrying component 11 is used to carry samples. In some examples, the sample carrying component 11 may include a sample delivery module (SDM) and a front-end injection track, which transports the sample tube to a predetermined position (sample position) for the sample dispensing mechanism 12 to absorb the sample; in other examples (for example, Figure 3 In the specific embodiment shown), the sample-carrying component 11 may also be a sample tray, which includes a plurality of sample positions such as sample tubes. The sample tray can dispatch the sample to a predetermined position, such as a position for the sample dispensing mechanism 12 to absorb the sample, by rotating its tray structure. The sample dispensing mechanism 12 is used to absorb the sample and discharge it into a reaction container to be loaded (such as a movable reaction cup or an immovable reaction pool). The sample dispensing mechanism 12 may include a sample needle and a needle moving mechanism, and the sample needle performs two-dimensional or three-dimensional movement in space through a two-dimensional or three-dimensional needle moving mechanism, so that the sample needle can move to absorb the sample carried by the sample-carrying component 11, and move to the position of the reaction container to be loaded, and discharge the sample into the reaction container.

[0047] The reagent component 20 is used to carry the reagent, and after absorbing the reagent, it is provided to the measuring component 30. In some embodiments, the reagent component 20 may include a reagent carrying component 13 and a reagent dispensing mechanism 14. The reagent carrying component 13 is used to carry the reagent. In one embodiment, the reagent carrying component 13 can be a reagent disk, which is arranged in a disc-shaped structure and has a plurality of positions for carrying reagent containers. The reagent carrying component 13 can rotate and drive the reagent container it carries to rotate, and is used to rotate the reagent container to a specific position, such as a position where the reagent is absorbed by the reagent dispensing mechanism 14. The number of reagent carrying components 13 can be one or more. The reagent dispensing mechanism 14 is used to absorb the reagent and discharge it into a reaction cup to be added with the reagent. In one embodiment, the reagent dispensing mechanism 14 may include a reagent needle and a needle moving mechanism, and the reagent needle performs two-dimensional or three-dimensional movement in space through a two-dimensional or three-dimensional needle moving mechanism, so that the reagent needle can move to absorb the reagent carried by the reagent carrying component 13, and move to the reaction cup to be added with the reagent, and discharge the reagent into the reaction cup. In another embodiment, the reagent dispensing mechanism 14 does not add the reagent by means of a reagent needle, but rather adds the reagent in the reagent tube to the reaction pool through a dedicated pipeline. In this embodiment, there is only a sample needle and no reagent needle.

[0048] The measuring unit 30 is used to perform a project test on the sample to obtain the test data of the project. In some embodiments, the measuring unit 30 may include a reaction mechanism 15 and a measuring mechanism 16. The reaction mechanism 15 has at least one placement position, which is used to place a reaction cup and incubate the reaction liquid in the reaction cup. For example, the reaction mechanism 15 may be a reaction disk, such as Figure 3 As shown, it is arranged in a disc-shaped structure and has one or more placement positions for placing reaction cups. The reaction disk can rotate and drive the reaction cups in its placement positions to rotate, which is used to arrange the reaction cups in the reaction disk and incubate the reaction liquid in the reaction cups. In other embodiments, the reaction mechanism can also be a fixed reaction cup placement position, and the reaction cup is placed in this position for a predetermined time to complete incubation and / or other operations (such as mixing). The measuring mechanism 16 is used to measure the reaction liquid after incubation to obtain the reaction data of the sample. For example, in one embodiment, the measuring mechanism 16 can be an optical measuring mechanism, which detects the optical signal after the reaction liquid to be tested is acted on by the optical measuring mechanism, and the control and data processing module 40 calculates the type and / or concentration of the component to be tested in the sample based on the collected optical signal. In one embodiment, the optical measuring component 16 is separately arranged outside the reaction component 15. In other embodiments, the measuring mechanism 16 can also be an electrical measuring mechanism (such as an impedance measuring mechanism) or a measuring mechanism based on other principles (such as an imaging measuring mechanism).

[0049] Depending on the different body fluids being tested and the different test items, there are different ways to add samples and reagents. For example, both samples and reagents can be added using a sampling needle, or only samples can be added using a sampling needle, while reagents are added using other methods. When adding using a sampling needle, in order to prevent the sampling needle from sucking in air or touching the bottom of the sample tube / reagent tube, the sampling needle is usually controlled to start sucking liquid (the liquid can be a sample or a reagent) only when it touches the liquid surface. In order to detect whether the sampling needle touches the liquid surface, in an embodiment of the present invention, the sampling needle uses a metal needle with a double-layer sleeve, and its structure is as follows: Figure 1 As shown, it includes a nested inner sleeve 1 and outer sleeve 2. The inner sleeve 1 and the outer sleeve 2 can be equivalent to a capacitor. When the sampling needle does not touch the liquid surface, the equivalent capacitance is called the background capacitance of the sampling needle. When the head of the sampling needle touches the liquid surface, the equivalent capacitance of the sampling needle changes.

[0050] The signal processing circuit 60 is electrically connected to the sampling needle 11a and the measuring component 30, and is used to convert, amplify, filter and process various electrical signals, and output the processed signals to the control and data processing module 40. The signal processing circuit 60 includes a liquid level detection circuit, such as Figure 4 As shown, the liquid level detection circuit 61 is electrically connected to the sampling needle 12a and is used to detect the equivalent capacitance of the sampling needle 12a. The sampling needle 12a is mounted on a needle moving mechanism 12b. The needle moving mechanism 12b can be an XYZ three-dimensional motion mechanism, enabling the sampling needle 12a to move vertically, left and right, and forward and backward. The needle moving mechanism 12b can also be a rocker mechanism that can be raised and lowered, enabling the sampling needle 12a to move vertically and rotate horizontally. The needle moving mechanism 12b drives the sampling needle 12a to move, allowing the sampling needle 12a to reach the sample aspiration position and the sample discharge position, thereby aspirating and discharging the sample. When the sampling needle 12a reaches the sample aspiration position, the needle moving mechanism 12b drives the sampling needle 12a downward into the container containing the liquid. When the tip of the sampling needle 12a contacts the liquid surface, the equivalent capacitance of the sampling needle 12a changes. The liquid level detection circuit 61 determines whether the tip of the sampling needle 12a has contacted the liquid surface based on this change in equivalent capacitance. When the head of the sampling needle 12a contacts the liquid surface, the liquid level detection circuit 61 outputs a level signal to the control and data processing module 40, which controls the liquid circuit system 70 to operate and control the sampling needle 12a to start sucking a predetermined amount of liquid.

[0051] The control and data processing module 40 is used to control the sample component 10 and the reagent component 20 to collect and discharge samples and reagents according to a set time sequence. Furthermore, the control and data processing module 40 is used to convert, compile statistics, analyze, and / or calculate the signals or data output by the assay component 30, ultimately obtaining test results related to the predetermined test items. These test results can be visualized as numerical values ​​or various graphs, tables, waveforms, etc. To prevent cross-contamination between different samples, the control and data processing module 40 also controls the fluid system 70 to provide cleaning fluid according to a set time sequence to clean the pipes and containers that come into contact with the samples and reagents.

[0052] The display unit 50 is used to display various test results. The display unit can include one display or multiple displays, and the number of displays is not limited. In addition, the display can also provide a graphical interface for human-computer interaction to the user while displaying graphics and text.

[0053] The fluid system 70 includes a drive component and a pipeline. The pipeline is used to connect the sampling needle and the cleaning fluid container. When a fixed reaction pool is included in the embodiment, the pipeline also connects to the reaction pool and is used to transport the cleaning fluid to the sampling needle and / or the reaction pool to achieve suction and discharge operations and cleaning of the sampling needle and / or the reaction pool. The drive component is used to provide power to change the flow direction of the fluid (e.g., cleaning fluid) in the pipeline. In some embodiments, the cleaning fluid is also used as a diluent to dilute the sample.

[0054] like Figure 4 As shown, the liquid line 71 is connected to the rear end of the sampling needle 12a. The other end of the liquid line 71 is connected to a drive component (not shown). The drive component operates to change the flow direction of the fluid (e.g., cleaning fluid or air) within the pipeline. For example, the drive component can be a syringe that changes the flow direction of the fluid within the pipeline by pushing or pulling. Alternatively, the drive component can be a bidirectional pump that changes the flow direction of the fluid within the pipeline by changing the pump's operating direction. When the sample analyzer is powered on and initialized, the drive component drives the cleaning fluid to fill the line 71 and the interior of the sampling needle 12a. The cleaning fluid displaces the air in the sampling needle 12a. When the sampling needle 12a touches the liquid surface, the control and data control module 40 controls the drive component to operate. The drive component drives the cleaning fluid in the liquid line 71 away from the sampling needle 12a. The sampling needle 12a absorbs the sample under the action of negative pressure. At this time, an air gap is formed between the absorbed sample and the cleaning fluid, isolating the sample and the cleaning fluid. When the sampling needle 12a needs to discharge the sample, the driving component drives the cleaning fluid in the pipeline 71 to continuously flow toward the sampling needle 12a, forcing the sample in the sampling needle 12a to be discharged out of the tube.

[0055] The liquid pipeline 71 is usually made of insulating material, but in some cases, a conductive cleaning liquid is used for the cleaning liquid. In order to avoid the interference of a certain link in the entire cleaning liquid pipeline being introduced into the metal needle when the cleaning liquid contacts the metal sampling needle, thereby making the liquid level detection function of the metal needle invalid or reduced, in this embodiment, a conductive medium is added to ground the cleaning liquid.

[0056] The present invention contemplates providing a grounded conductor in a liquid system, wherein at least a portion of the conductor is in contact with the liquid flowing through the pipeline, thereby grounding the liquid in the pipeline. The liquid in the pipeline can be a cleaning liquid or a diluent. There are various schemes for grounding the liquid, such as placing the liquid in a metal container, or placing the liquid in contact with metal, and then connecting the metal to the earth. For schemes in which the liquid is placed in a metal container, it is difficult to place the grounding point in the optimal position, resulting in poor grounding effect. For schemes in which the liquid flows through metal and then connects the metal to the earth via a wire, there are also various ways, such as making the metal part of the pipeline, or making the metal into a sharp shape, with one sharp end inserted into the pipeline to contact the cleaning liquid and the other end grounded.

[0057] In one embodiment of the present invention, a solution is adopted in which metal is used as a part of the pipeline and then the metal is connected to the ground through a wire, such as Figure 4 As shown, the conductor 72 includes a metal two-way joint 72a and a grounding component 72b. The two-way joint 72a is connected to the pipeline 71 to form a channel for liquid circulation. One end of the grounding component 72b is fixedly connected to the two-way joint 72a, and the other end is used to connect to the ground. Figure 4 In the illustrated embodiment, the pipeline 71 includes a separate first pipeline 71a and a second pipeline 71b. The first end of the first pipeline 71a is connected to the sampling needle 12a, and the second end thereof is connected to the first end of the two-way connector 72a; the first end of the second pipeline 71b is connected to the second end of the two-way connector 72a, and the second end thereof is connected to the driving component. In another embodiment, the two-way connector 72a can also be connected between the pipeline 71 and the sampling needle. By grounding the grounding component 72b, the cleaning liquid in contact with the two-way connector 72a is grounded, thereby preventing the cleaning liquid from introducing electrical interference from other parts of the analyzer into the metal needle, which is equivalent to filtering the electrical interference. This grounding method has fewer process steps, high connection reliability, better impedance control, and high overall cost performance.

[0058] To prevent impurities from depositing on the tube wall due to changes in flow resistance, which could affect sample addition accuracy, the diameter of the cleaning liquid circulation pipeline is maintained as consistent as possible. In a preferred embodiment, the diameter of the central lumen of the two-way connector matches, and is particularly equal to, the diameter of the lumen of the pipeline. The diameters of the lumen at the first and second ends of the two-way connector are larger than the lumen of the pipeline. The first and second ends of the two-way connector are tightly fitted onto the second end of the first pipeline and the first end of the second pipeline, respectively.

[0059] In practical applications, if the solution described in this embodiment is to achieve good filtering effects without affecting the existing detection system, the following difficulties or problems need to be solved:

[0060] 1. Determination of grounding position

[0061] When a conductor in contact with the cleaning fluid in the pipeline is grounded, the impedance between the grounding connector and the metal needle is equivalent to a resistor in parallel with the metal needle. The equivalent resistance varies depending on the cleaning fluid grounding location. The choice of grounding location can affect two key aspects: first, the effectiveness of the grounding. Different equivalent resistances can affect the grounding effect, leading to varying interference filtering. Second, whether the liquid level detection circuit will be affected.

[0062] According to theoretical analysis, the farther the cleaning liquid grounding position is from the metal needle, the longer the filter blind zone (the distance between the grounding position and the needle) is. Combined with the interference model, if the distance exceeds 1000mm, the grounding effect on the liquid level detection filtering is weak. The actual measurement also proves this speculation. However, it does not mean that the closer the cleaning liquid grounding position is to the metal needle, the better. According to theoretical calculation: board capacitance Cp = 56Pf, sampling needle capacitance C 1A =40+10Pf, the calculated resonant frequency is 375KHz, and the sampling needle capacitance impedance is about 4.4K. In order to minimize the impact of the resistance introduced by grounding on the system, the resistance that needs to be introduced is much larger than the capacitance impedance. For liquids, the longer the pipeline, the greater the impedance, so the distance between the grounding point and the sampling needle should be as far as possible. Actual measurements have shown that when the grounding point is in the range of 10mm-1000mm from the sampling needle, the filtering effect can meet the instrument requirements. For example, when the grounding point is 10mm away from the sampling needle, according to the measured data, the impedance corresponding to the cleaning fluid at this time is about 3.1K, and the filtering effect can meet the instrument requirements. Of course, those skilled in the art should understand that the cleaning liquid grounding position can also be set at a position farther or closer to the sampling needle.

[0063] The analysis of whether the second grounding point will affect the liquid level detection circuit is as follows:

[0064] Liquid level detection circuit Figure 5a As shown in the figure, C Pis the equivalent capacitance output by the sampling needle, and R is the equivalent resistance introduced by the grounding conductor, that is, R=R1+R2. In the liquid grounding experiment, the impedance of the cleaning fluid between the grounding joint and the metal needle can be equivalent to a resistor in parallel with the metal needle, which is named R here. R and C P Connected in parallel to both ends of the tuning capacitor C1 of the phase-locked loop, the resonant frequency of the system can be calculated as follows:

[0065]

[0066] Where I3 is the current flowing through the tuning capacitor C 1A and C P The total current is determined by the external resistors Ra and Rb. Since the resistance values ​​of Ra and Rb remain basically unchanged during the improvement process, I3 can be regarded as a constant current source. Since the current source I3 remains constant, the resistor R will divide part of the current, so the current flows through the capacitor C. 1A and C P The current is bound to decrease, such as Figure 5b As shown, the resonant frequency f of the phase-locked loop is reduced.

[0067] However, if the on-resistance R is controlled within a certain range, the resonant frequency f will not change, and thus the output voltage of the liquid level detection system will not change. Therefore, by controlling the distance between the metal connector and the metal needle, the on-resistance R of the conductive liquid within this distance can be controlled within a certain range, thereby reducing the impact on the liquid level detection circuit.

[0068] 2. Ground impedance of conductor

[0069] After determining the grounding position of the conductor in the pipeline, the equivalent resistance of the conductor needs to be considered. First, a theoretical analysis is performed. Figure 4 The pipe on the left side of the metal union (such as Figure 6 The impedance of the liquid in the needle moving mechanism is defined as R2, and the impedance between the metal joint and the metal support frame of the needle moving mechanism (the whole machine ground) is defined as R1.

[0070] To determine the impedance of R1, we must first determine the size of R2. Since the liquid in the pipeline is a cleaning fluid, it contains a variety of ions and is a general conductor with a certain conductivity. Its resistance is determined by its composition. The impedance test of the cleaning fluid in a pipeline with an inner diameter of 1 / 16 inch (i.e. 1.5875 mm) was performed. The results are shown in Table 1:

[0071] Table 1 Liquid impedance test results

[0072] frequency 10mm impedance (liquid static) 10mm impedance (liquid flow) 100Hz 5Kohm 5.1Kohm 10KHz 3.21Kohm 3.32Kohm 20KHz 3.27Kohm 3.37Kohm 100KHz 3.1Kohm 3.27Kohm

[0073] After testing, it is known that when the length of the R2 section is 10mm, the resistance range of R2 is 3.1Kohm-5.2Kohm. According to the filtering principle, if you want to achieve the function of filtering and anti-interference, you need to let the interference signal pass through the low-resistance path R1, such as Figure 7 As shown, it is necessary to make R1 < <R2。

[0074] According to the comparative test, when R1>10ohm, the filtering effect is not good. When R1<=10ohm, the filtering effect is good and the interference signal in the pipeline is completely filtered out. Figure 8a The waveform shown is the waveform of the liquid level detection being disturbed. Figure 8b The figure shows the liquid level detection waveform when the grounding scheme of the present invention is used and R1 is less than or equal to 10 ohms. As can be seen from the figure, the detection signal is stable and there is basically no interference. This shows that the solution of grounding the cleaning liquid proposed by the present invention can block the interference of the cleaning liquid introduced into other parts of the analyzer on the liquid level detection, thereby improving the accuracy of the liquid level detection results.

[0075] 3. Grounding process

[0076] for Figure 4 The difficulty of the embodiment shown is how to connect the two-way connector 72a to the ground through the grounding component 72b. For example, a wire is used as the grounding component 72b and the wire is directly welded to the surface of the metal two-way connector 72a. However, the wire is easy to fall off or increase the equivalent impedance, thereby causing the filtering function of the liquid level detection circuit to fail.

[0077] In one embodiment of the present invention, Figure 9 As shown, the grounding conductor includes a metal coupling 72a and a grounding component 72b. The grounding component 72b is a metal connector. One end of the metal connector is welded to the surface of the coupling 72a, and the other end is welded to the metal support frame 12c of the needle moving mechanism, or fixed to the metal support frame 12c of the needle moving mechanism by screws or bolts. Since the metal support frame 12c of the needle moving mechanism is connected to the entire ground of the sample analyzer, the grounded metal support frame 12c component 72b is also connected to the ground, thereby connecting the coupling 72a and the cleaning fluid in contact with the coupling 72a to the ground.

[0078] As for the grounding method of the grounding component 72b, those skilled in the art should understand that it is not limited to being connected to the ground through the metal support frame 12c. In other embodiments, the grounding component 72b can be connected to any metal part of the needle moving mechanism that is connected to the ground of the entire machine, or to any metal part of the sample analyzer that is connected to the ground of the entire machine (such as the grounding position of the circuit board), and be grounded through the metal part, or the grounding component 72b can also be directly or indirectly connected to the ground of the entire machine through a wire.

[0079] In another embodiment of the present invention, Figure 10 As shown, the two-way connector 72a and the grounding component 72b are an integrally formed structure, and the grounding component 72b is fixed to the metal support frame 12c of the needle moving mechanism by screws or bolts.

[0080] In other embodiments, the conductor may be in direct contact with the cleaning fluid. For example, the conductor may include a puncture wire, one end of which is inserted into the lumen of the pipeline and the other end is grounded, thereby grounding the cleaning fluid.

[0081] 4. Solutions to prevent the impact of grounding on the performance of the liquid level detection circuit

[0082] The impact of grounding the cleaning fluid on liquid level detection accuracy is primarily due to changes in the resistance of the liquid in the pipeline between the grounding point and the needle due to flow, temperature, and other factors. This affects the resonant frequency of the liquid level detection circuit, which in turn affects the phase-locked loop (PLL) output voltage. Since the resistance of the liquid in the pipeline between the grounding point and the needle can be thought of as a resistor R connected in parallel with the sampling needle (as mentioned above, the typical static resistance is approximately 3.1kohm + 10ohm), theoretically, when a resistor is connected in parallel with the sampling needle, any changes in this resistance will affect the resonant frequency of the liquid level detection circuit, causing the PLL output voltage to shift, thus affecting the accuracy of liquid level detection.

[0083] In order to reduce the above-mentioned influence, in one embodiment, a calibration circuit is added to the liquid level detection circuit, such as Figure 11 As shown, the liquid level detection circuit 61 includes a calibration circuit 611, a phase-locked loop 612, and a processing circuit 613 connected in sequence. The calibration circuit 611 is connected to the sampling needle, accesses the equivalent capacitance of the sampling needle, and is used to compensate for the equivalent resistance introduced by grounding. The phase-locked loop 612 is connected to the oscillation source 610 and the output end of the calibration circuit 611 respectively, and is used to generate a resonant frequency, convert the detected equivalent capacitance of the sampling needle into a voltage signal, and output the voltage signal to the processing circuit 613. The processing circuit 613 is used to process the voltage signal and determine whether the sampling needle is in contact with the liquid surface based on the voltage signal. In one embodiment, the processing circuit 613 includes a signal conditioning circuit 613a, a signal acquisition circuit 613b, and a processor 613c. The signal conditioning circuit 613a is used to amplify and / or filter the voltage signal. The signal acquisition circuit 613b is used to sample the signal and perform A / D conversion on the signal. The processor 613c is used to compare the signal with a set threshold value to determine whether the sampling needle is in contact with the liquid surface and output the judgment result to the control and data processing module.

[0084] In one embodiment, the calibration circuit 611 uses a symmetrical capacitor connection, such as Figure 12As shown, the calibration circuit includes a first capacitor C1 and a second capacitor C2 connected in series at the two input terminals of the phase-locked loop. The capacitance of the first capacitor C1 and the second capacitor C2 are equal, and the middle node between the two is used to connect the equivalent capacitance C of the metal needle. P The output terminal of the PLL is shown in the figure, where R is the equivalent resistance introduced by the grounding conductor. This solution can reduce the impact of the parallel resistance R introduced by the grounding of the cleaning fluid on the output voltage of the PLL.

[0085] In some implementations, the capacitance of the first capacitor C1 and the second capacitor C2 is 1 to 3 times the background equivalent capacitance of the metal needle. Furthermore, the capacitance of the first capacitor C1 and the second capacitor C2 is 1.5 to 2.5 times, preferably 2 to 2.5 times, the background equivalent capacitance of the metal needle.

[0086] In a preferred embodiment, the capacitance of the first capacitor C1 and the second capacitor C2 is approximately twice the background equivalent capacitance of the metal needle, so that the effect of the parallel resistor R on the output voltage of the phase-locked loop can be ignored.

[0087] For example, the background equivalent capacitance of the metal needle is 45 pF, and the capacitance of the first capacitor C1 and the second capacitor C2 can be selected from 90 pF to 135 pF, for example, 90 pF, or both equal to 100 pF, or both equal to 110 pF.

[0088] Through actual measurement, it is known that when the R value of the circuit using the asymmetric connection method changes, the output voltage of the phase-locked loop fluctuates greatly, as shown in Table 2.

[0089] Table 2 Test results of phase-locked loop output voltage in asymmetric connection

[0090]

[0091] When the R value of the liquid level detection circuit is connected symmetrically, the fluctuation of its phase-locked loop output voltage is small and can be ignored, as shown in Table 3.

[0092] Table 3. Test results of phase-locked loop output voltage in symmetrical connection

[0093]

[0094] The process of liquid level detection using the sample analyzer of the above solution is as follows:

[0095] When the sample analyzer is powered on and initialized, cleaning fluid is driven into the tubing and metal needle. A metal connector embedded in the tubing grounds the cleaning fluid inside the tubing and the metal needle. The liquid level detection function is then activated, driving the metal needle downward toward the surface of the liquid to be drawn. During this downward movement, the needle's electrical characteristic (e.g., capacitance) is measured in real time. Changes in this characteristic determine whether the needle has contacted the liquid surface.

[0096] The present invention grounds the cleaning liquid, thereby filtering out interference with liquid level detection caused by other parts of the analyzer without affecting normal detection. The solution of the present invention is simple, cheap, and effective, and is particularly suitable for online upgrading of sold models.

[0097] The above examples are used to illustrate the present invention, which are only used to help understand the present invention and are not intended to limit the present invention. Those skilled in the art can make several simple deductions, modifications or substitutions based on the concept of the present invention.

Claims

1. A sample analyzer, characterized in that include: a metal needle, the metal needle being used for adding a sample and / or a reagent and being configured to change its own electrical properties when it contacts a liquid surface; A needle moving mechanism, used for supporting the metal needle and driving the metal needle to move; Drive components for providing power; A pipeline for transporting cleaning liquid, one end of the pipeline being connected to the metal needle and the other end being connected to the driving component, so that the driving component changes the flow direction of the cleaning liquid in the pipeline, causing the metal needle to absorb or discharge the liquid; a conductor, at least a portion of which is in contact with the liquid flowing through the pipeline, and the conductor is further connected to ground; A liquid level detection circuit, wherein the input end of the liquid level detection circuit is used to be electrically connected to the metal needle, for monitoring the changes in the electrical characteristics of the metal needle, and judging whether the metal needle contacts the liquid surface according to the changes in the electrical characteristics of the metal needle.

2. The sample analyzer according to claim 1, wherein The conductor includes a metal two-way joint and a grounding component. The two-way joint is connected to the pipeline to form a channel for liquid circulation. One end of the grounding component is fixedly connected to the two-way joint, and the other end is used to be connected to the ground.

3. The sample analyzer according to claim 2, wherein: The pipeline includes a separate first pipeline and a second pipeline, the first end of the first pipeline is connected to the metal needle, and the second end thereof is connected to the first end of the two-way connector; the first end of the second pipeline is connected to the second end of the two-way connector, and the second end thereof is connected to the driving component.

4. The sample analyzer according to claim 3, wherein: The length of the first pipeline ranges from 10 mm to 1000 mm.

5. The sample analyzer according to claim 3, wherein: The diameter of the middle inner cavity channel of the two-way connector matches the inner cavity diameter of the pipeline, the diameters of the inner cavity channels at the first and second ends of the two-way connector are larger than the inner cavity diameter of the pipeline, and the first and second ends of the two-way connector are tightly fitted on the second end of the first pipeline and the first end of the second pipeline respectively.

6. The sample analyzer according to claim 2, wherein: The equivalent resistance of the conductor is less than or equal to 10Ω.

7. The sample analyzer according to claim 2, wherein: The other end of the grounding component is fixed on a metal support frame of the needle moving mechanism or a grounding position of a circuit board.

8. The sample analyzer according to claim 2, wherein: The metal two-way joint and the grounding component are an integrally formed structure; or the grounding component is a metal connector or a wire.

9. The sample analyzer according to claim 1, wherein: The conductor comprises a puncture wire, one end of which is inserted into the lumen of the pipeline from the pipeline body, and the other end of which is grounded.

10. A sample analyzer, characterized in that include: A pipeline for transporting cleaning liquid, the pipeline being connected to the metal needle, and causing the metal needle to absorb or discharge the liquid by changing the flow direction of the cleaning liquid in the pipeline; a conductor, at least a portion of which is in contact with the liquid flowing through the pipeline, and the conductor is further connected to ground; A liquid level detection circuit, wherein the input end of the liquid level detection circuit is used to be electrically connected to the metal needle, for monitoring the changes in the electrical characteristics of the metal needle, and judging whether the metal needle contacts the liquid surface according to the changes in the electrical characteristics of the metal needle.

11. The sample analyzer according to claim 1 or 10, wherein: The electrical characteristic of the metal needle is capacitance. The liquid level detection circuit includes a calibration circuit, a phase-locked loop and a processing circuit connected in sequence. The calibration circuit includes a first capacitor and a second capacitor connected in series at the two input ends of the phase-locked loop. The capacitance values ​​of the first capacitor and the second capacitor are equal, and the intermediate node between the two is used to connect the equivalent capacitance output end of the metal needle.

12. The sample analyzer according to claim 11, wherein: The capacitance of the first capacitor and the second capacitor is equal to 1 to 3 times the background equivalent capacitance of the metal needle.

13. The sample analyzer according to claim 12, wherein: The capacitance of the first capacitor and the second capacitor is equal to 1.5 to 2.5 times the background equivalent capacitance of the metal needle.

14. The sample analyzer according to claim 13, wherein: The capacitance of the first capacitor and the second capacitor is equal to 2 to 2.5 times the background equivalent capacitance of the metal needle.

15. The sample analyzer according to claim 14, wherein: The capacitance of the first capacitor and the second capacitor is equal to twice the background equivalent capacitance of the metal needle.

16. The sample analyzer according to claim 10, wherein: The conductor includes a metal two-way joint and a grounding component, the two-way joint is connected to the pipeline to form a channel for liquid circulation, one end of the grounding component is fixedly connected to the two-way joint, and the other end is used to be connected to the ground; or the conductor includes a puncture wire, one end of the puncture wire is inserted into the lumen of the pipeline through the pipe body, and the other end is grounded.

17. A liquid path system of a sample analyzer, characterized in that include: A pipeline for transporting cleaning fluid, one end of the pipeline being connected to the metal needle and the other end being connected to the driving component, so that the driving component changes the flow direction of the fluid in the pipeline, causing the metal needle to absorb or discharge the liquid. The pipeline includes a separate first pipeline and a second pipeline, the first pipeline and the second pipeline being connected to the metal needle and the driving component, respectively; The conductor includes a metal two-way joint and a grounding component. The two-way joint is connected between the first pipeline and the second pipeline, and together with the pipeline forms a channel for liquid circulation. One end of the grounding component is fixedly connected to the two-way joint, and the other end is used to be connected to the ground.

18. A liquid level detection method, characterized in that include: Drive the cleaning fluid to fill the pipe and metal needle; Ground the cleaning fluid in the tubing and metal needle; The metal needle is driven downward to approach the liquid surface to be sucked, and the electrical characteristic value output by the metal needle is detected in real time during the downward movement of the metal needle; Whether the metal needle touches the liquid surface is determined based on the change in the electrical characteristic value.

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