A liquid path system for sampling quality detection and an abnormal detection process

Abstract

The present invention belongs to the technical field of biological liquid sample detection, and particularly relates to a liquid path system for sampling quality detection and an abnormal detection process. A liquid path system for sampling quality detection includes a capacitance detection module, a syringe, a pressure detection module, a cleaning valve, a cleaning pump, a degassing module, and a water tank that are connected in sequence. The capacitance detection module, the syringe, the pressure detection module, the cleaning valve, the cleaning pump, the degassing module, and the water tank are connected by pipelines. The following problems are mainly solved: 1. The contradiction between the pressure monitoring range and the monitoring resolution; 2. When the sample is insufficient or air bubbles are inhaled, the difference in the suction pressure and the normal liquid suction pressure is small, which is likely to cause misjudgment; 3. It is easily interfered by noise signals, resulting in misjudgment; 4. There is a lack of corresponding error monitoring mechanisms in other processes such as cleaning and sample addition; 5. Excessive reliance on a single method for monitoring, and the pressure during the test is easily interfered with.

Description

Technical Field

[0001] The present invention belongs to the technical field of biological liquid sample detection, and in particular relates to a liquid path system for sample aspiration quality detection and an abnormality detection process. Background Art

[0002] In vitro diagnostic devices (IVDs) are medical devices that test and analyze human samples (such as blood, urine, and tissue fluid) collected outside the human body to obtain clinical diagnostic information, monitor disease status, or evaluate physiological functions. These devices are widely used in various medical scenarios and are crucial for disease prevention, diagnosis, treatment monitoring, and health management. There are many types of IVDs, which can be divided into biochemical analyzers, immunoassay analyzers, hematology analyzers, molecular diagnostic instruments, microbiology analyzers, coagulation analyzers, urine analyzers, and POCT (point-of-care) devices, depending on the detection principle, target analyte, and application scenario.

[0003] Currently, the development trend of in vitro diagnostic instruments is toward high speed, high precision, and high automation. The accuracy and speed of the sample addition process are key factors influencing instrument performance. As the sample volume required for a single test decreases, the demand for sample addition accuracy is also increasing. Any interference or deviation during the sample addition process can lead to erroneous test results. Therefore, effective status monitoring of the sample addition process is crucial to ensure accurate sample and reagent liquid transfer and addition during testing.

[0004] In practical applications, the complexity of the sample being transferred can easily lead to deviations in aspiration and sample addition. Typical problems include: clogged aspiration needles, insufficient sample, and air bubble interference.

[0005] Currently, the means for monitoring the quality of sample transfer mainly involve monitoring the pressure change during the sample aspiration process. There are mainly the following problems in detecting the pressure change during the sample aspiration process: 1. The contradiction between the pressure monitoring range and the monitoring resolution: Since the aspiration needle is generally pressurized for flushing during cleaning to ensure thorough flushing, the cleaning pressure is relatively high (usually several hundred kilopascals), so a relatively large monitoring and pressure resistance range is required for the pressure sensor. However, during the sample aspiration process, as the sample volume becomes less and less, the pressure change is relatively small (several kilopascals) during the aspiration of a small amount of liquid. Therefore, a high monitoring accuracy and resolution are required for the low-pressure part of the pressure sensor; 2. Currently, pressure monitoring is mainly used for needle blockage monitoring with relatively high accuracy and reliability because the suction pressure during needle blockage is significantly different from the normal liquid suction pressure, making it less likely to cause misjudgment. However, when the sample is insufficient or air bubbles are inhaled, the difference between the suction pressure and the normal liquid suction pressure is relatively small, making it easy to cause misjudgment; 3. When the aspirated sample volume is small, due to the low aspiration speed or short aspiration time, the pressure difference signal is small and is easily interfered by noise signals, resulting in misjudgment; 4. Only the sample aspiration process is monitored, and there is no corresponding error monitoring mechanism in other processes such as cleaning and sample addition; 5. Excessive reliance on a single method (pressure) for monitoring, and the pressure during the test process is easily interfered, resulting in a reduction in the reliability of the system.

[0006] In order to overcome the shortcomings of detecting the pressure change during sample aspiration in the prior art, the present invention aims to provide a liquid path system and software system for detecting the quality of sample aspiration. Summary of the Invention

[0007] The purpose of the present invention is to provide a liquid path system for detecting the quality of sample aspiration and an abnormal detection process to solve the problems raised in the above background technology.

[0008] To achieve the above purpose, the present invention provides the following technical solutions:

[0009] A liquid path system for detecting the quality of sample aspiration includes a capacitance detection module, a syringe, a pressure detection module, a cleaning valve, a cleaning pump, a degassing module, and a water tank connected in sequence. The capacitance detection module, syringe, pressure detection module, cleaning valve, cleaning pump, degassing module, and water tank are connected by pipelines.

[0010] The capacitance detection module includes an aspiration needle for collecting capacitance signals. Further, the collected capacitance signals are input to an oscillator after signal filtering. The frequency signal output by the oscillator is divided by a frequency divider and then input to a counter of the first control unit for frequency signal measurement. Further, the measured frequency signal is reported through the first communication unit.

[0011] The pressure detection module includes a pressure sensor. The pressure sensor collects signals and converts them into electrical signals. The collected signals are first amplified and then filtered. Further, they are simultaneously amplified a second time in the high-pressure channel and the low-pressure channel. The first analog-to-digital conversion module and the second analog-to-digital conversion module of the second control unit simultaneously collect and convert the electrical signals amplified a second time in the high-pressure channel and the low-pressure channel respectively, converting the analog electrical signals into digital signals. By identifying the digital signals, it is determined whether a pressure anomaly has occurred. Further, the pressure data is reported through the second communication unit and stored in the storage unit.

[0012] Preferably, the sampling needle adopts a double-layer metal structure with an inner wall and an outer wall nested. The outer wall of the sampling needle is fixed on the sample arm moving component, and an insulating layer is provided between the inner wall and the outer wall of the sampling needle. A capacitance detection module is provided on the sample arm moving component, and the inner wall and the outer wall of the sampling needle are simultaneously connected to the signal input end of the capacitance detection module.

[0013] Preferably, the pressure sensor is installed vertically.

[0014] Preferably, the pressure sensor is installed between the cleaning valve and the syringe, and the pipeline between the pressure sensor and the syringe is ≤200 mm.

[0015] Preferably, the pipeline is a rigid pipe, the movable part of the pipeline is U-shaped, and the U-shaped angles of the movable parts of several pipelines are the same.

[0016] An abnormal detection process for a liquid path system for detecting the quality of sampling includes the following steps:

[0017] Step 5: The sampling needle probes down into the liquid surface, waits for a delay until the pressure is stable, and measures the initial pressure P0.

[0018] Step 6: The syringe starts to sample, and the real-time pressure Pr during sampling is measured. When P0 - Pr > the needle-blocking threshold, sampling ends and a needle-blocking report is given. When P0 - Pr ≤ the needle-blocking threshold, the syringe is in the uniform speed section, waits for a delay until the real-time pressure is stable, and calculates the slope Kp of the pressure data in the uniform speed section at this time.

[0019] Step 7: When the data fluctuation of Kp exceeds the limit, sampling ends and a report of air bubbles being inhaled is given. When the data fluctuation of Kp does not exceed the limit, it is judged whether the syringe starts to decelerate.

[0020] Step 8: When the syringe does not start to decelerate, it is judged whether sampling is completed. If sampling is not completed, return to Step 6 and start Step 6 again.

[0021] Step 9: When the syringe starts to decelerate, measure the real-time pressure Pp before deceleration; when P0 - Pp < the air aspiration threshold, end the sample aspiration and report air aspiration; when P0 - Pp ≥ the air aspiration threshold, determine whether the sample aspiration is completed. If the sample aspiration is not completed, return to Step 6 and restart Step 6;

[0022] Step 10: When it is determined that the sample aspiration is completed in Steps 8 and 9, the syringe stops and the end pressure Pend is measured; if P0 - Pend > the partial blockage threshold, report partial blockage; when P0 - Pend ≤ the partial blockage threshold, the liquid path is normal.

[0023] Preferably, after the sampling needle detects one sample, replace the sample of the sampling needle. Before replacing the new sample, clean the sampling needle; during the cleaning process of the sampling needle, judge the situation of cleaning needle blockage. The steps for judging the cleaning needle blockage include the following:

[0024] Step 1: Judge whether the cleaning is completed: If the cleaning is not completed, return for cleaning and judge whether the cleaning is completed; if the cleaning is completed, delay and wait for the real-time pressure to stabilize;

[0025] Step 2: If the real-time pressure P > the cleaning blockage threshold, end normally; if the real-time pressure P ≤ the cleaning blockage threshold, report cleaning needle blockage.

[0026] Preferably, before the sampling needle is sampled after cleaning, judge the needle blockage situation of the sampling needle. The steps for judging the needle blockage are as follows:

[0027] Step 3: Judge whether the aspiration of isolation air is completed: If the aspiration of isolation air is not completed, return to re-end the aspiration of isolation air; if the aspiration of isolation air is completed, judge whether the pressure P < the normal recovery pressure is established;

[0028] Step 4: If the pressure P < the normal recovery pressure, end normally; if the pressure P ≥ the normal recovery pressure, report needle blockage before sampling.

[0029] Preferably, the detection steps for abnormal capacitance during the sampling process are as follows:

[0030] (1) The sampling needle descends to the liquid level. If the liquid level is detected, start sampling;

[0031] (2) After the liquid suction starts, detect whether the sampling needle is separated from the liquid level; if so, report insufficient sampling, end the sampling, and the sampling needle rises; if not, judge whether the sampling is completed;

[0032] (3) If the sampling is not completed, return to Step 2 to detect whether the sampling needle is separated from the liquid level; if the sampling is completed, the sampling needle rises, and further detect whether the sampling needle is separated from the liquid level;

[0033] (4) If the sampling needle is out of the liquid level, the process ends normally; if the sampling needle is not out of the liquid level, an abnormal liquid level detachment is reported.

[0034] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0035] (1) For the liquid path system for sampling quality detection provided by the present invention, the pressure sensor is vertically installed to facilitate the discharge of air bubbles; hard pipes should be used for the pipeline to reduce its own fluctuations, and the pipeline should be fixed to minimize the shaking of the pipeline during the operation of the sample arm; for the parts of the pipeline that need to move up and down, the U-shaped method is adopted, and the U-shaped angle should be kept consistent during operation; the length of the pipeline between the sampling needle and the syringe should not be too long, and bends, entanglements, transfers, diameter changes, etc. should be avoided (minimized as much as possible); the pipeline should not be too thin, as this will cause the frictional resistance along the pipeline section to increase and amplify the pressure fluctuations of the pipeline.

[0036] (2) For the liquid path system for sampling quality detection provided by the present invention, the sampling needle adopts a double-layer metal structure with an inner wall and an outer wall nested. The outer wall of the sampling needle is fixed on the sample arm moving component, and an insulating layer is provided between the inner wall and the outer wall of the sampling needle; a capacitance detection module is provided on the sample arm moving component, and both the inner wall and the outer wall of the sampling needle are connected to the signal input end of the capacitance detection module; by detecting the capacitance between the inner and outer walls of the needle, the capacitance detection module can determine the current environment of the sampling needle (in the air or in the liquid), so as to realize the liquid level contact detection of the sampling needle; the control unit controls the movement of the sample arm through the driving unit to realize the movement of the sampling needle to detect the liquid level. When the needle touches the liquid level, the capacitance detection module detects the capacitance change and sends it to the first control unit, and the first control unit controls the driving unit to stop moving, thus realizing accurate liquid level detection; during the sampling process, the sampling needle should always be in the liquid to be aspirated, and its capacitance value should remain stable. If the liquid volume is insufficient and air is inhaled, the detection of the capacitance value during the sampling process can also be used to detect the air aspiration during sampling.

[0037] (3) For the liquid path system for sampling quality detection provided by the present invention, a dual-channel design is adopted for the pressure detection module, enabling the same pressure sensor to monitor two pressure channels, namely high and low pressure channels simultaneously. The high-pressure channel ensures the high-pressure monitoring range during processes such as cleaning and needle clogging, while the low-pressure channel ensures the detection resolution of small pressure differences during processes such as aspiration of a small amount of samples.

[0038] (4)The liquid path system for sampling quality detection provided by the present invention has a change in the body capacitance value during the movement of the sampling needle. After being collected by the signal acquisition circuit and filtered, it is input to the oscillator. The output signal frequency of the oscillator changes with the change of the capacitance signal. After the output frequency signal is divided by the frequency divider, it is input to the control unit counter to measure the frequency signal. When the sampling needle enters or leaves the liquid surface, the capacitance value of the needle changes, and this changed capacitance value causes the frequency of the output signal to change. Therefore, a signal with a completely different frequency is generated and input to the control unit. By processing the signal in real time through the internal algorithm of the control unit, it can be recognized whether the sampling needle enters or leaves the liquid surface, and then reported through the communication unit. Since the small change in capacitance value is difficult to be detected by the control unit, this solution directly converts the change in capacitance value into the change in the frequency of the electrical signal, and utilizes the advantage of the accurate counting of the control unit to make the judgment of the control unit more accurate. Description of the Drawings

[0039] Figure 1 It is the connection diagram of the liquid path system of the present invention;

[0040] Figure 2 It is the connection diagram of the sampling needle capacitance detection module;

[0041] Figure 3 It is the structural schematic diagram of the pressure detection module of the present invention;

[0042] Figure 4 It is the structural schematic diagram of the capacitance detection module of the present invention;

[0043] Figure 5 It is the real-time pressure change curve graph of the liquid path during the normal sampling process;

[0044] Figure 6 It is the real-time pressure signal before and after the 20th-order 12Hz digital FIR low-pass filtering;

[0045] Figure 7 It is the pressure change curve when the sampling needle is completely blocked during sampling;

[0046] Figure 8 It is the pressure change curve when the sampling needle is partially blocked during sampling;

[0047] Figure 9 It is the pressure change curve when the sampling needle fails to suck the sample completely;

[0048] Figure 10 It is the pressure curve of partial empty suction with different ratios (actual water absorption volume / target water absorption volume);

[0049] Figure 11 It is the pressure curve of inhaled air bubbles;

[0050] Figure 12 It is the pressure anomaly detection process for the complete sampling process of the sampling needle;

[0051] Figure 13 It is the pressure change curve during the cleaning process;

[0052] Figure 14 It is the cleaning needle blockage detection process;

[0053] Figure 15 It is the needle blockage detection process before sampling;

[0054] Figure 16 It is the capacitance change during the normal sampling process;

[0055] Figure 17 It is the capacitance change during the abnormal sampling process;

[0056] Figure 18 It is the flow chart for detecting capacitance anomaly during the sampling process. Specific implementation manners

[0057] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the protection scope of the present invention.

[0058] The relevant liquid path structure of the sampling needle of the analyzer is as Figure 1 .

[0059] Among them, the cleaning pump is responsible for providing the cleaning pressure for the inner wall of the needle. The cleaning valve corresponding to the needle to be cleaned is opened during cleaning, and the cleaning water flows out from the inner wall of the needle; during sample suction and discharge, the cleaning valve remains closed, and the syringe completes sample suction and discharge. The pressure detection module is installed between the cleaning valve and the sampling needle, where both the cleaning pressure and the sample suction and discharge pressure can be detected.

[0060] During cleaning, the pressure of the entire sampling needle liquid path changes greatly, so there are no special requirements for the installation position of the sensor; during sampling, the pressure of the sampling needle liquid path changes little, and the sensor needs to be installed at the pressure-sensitive part. Since the syringe is the pressure change source during sampling of the sampling needle, the sensor should be placed near the syringe.

[0061] Bubbles have a certain elasticity, and their existence will affect the pressure change law of the liquid path. Generally, it will cause false detection of air aspiration. The situation of bubbles existing in liquid path components such as needles, pipelines, pressure sensors, and syringes must be avoided. Therefore, the degassing module is very necessary.

[0062] In addition, vibration of the pump, pipeline and sensor will cause abnormal pressure fluctuations, resulting in false detection of empty suction. Vibration of liquid circuit components should be avoided.

[0063] The experiment also found that too many pipe bends, windings, transitions and diameter changes will affect the differentiation of air suction and should be avoided.

[0064] Capacitance detection structure such as Figure 2 shown.

[0065] The sample aspirator adopts a double-layer metal structure with inner and outer layers nested inside and outside. The outer wall of the needle is fixed to the sample arm moving assembly. The inner and outer layers are insulated, so there is a certain capacitance between the inner and outer walls of the needle. The inner and outer walls are simultaneously connected to the signal input end of the capacitance detection module, which is also fixed to the moving assembly. The capacitance detection module can determine the current environment of the sample aspirator (in air or liquid) by detecting the capacitance between the inner and outer walls of the needle, thereby realizing liquid surface contact detection of the sample aspirator.

[0066] The control unit controls the movement of the sample arm through the drive unit, so that the sample suction needle moves to detect the liquid surface. When the needle touches the liquid surface, the capacitance detection module detects the capacitance change and sends it to the control unit. The control unit controls the drive unit to stop moving, thereby achieving accurate liquid level detection.

[0067] At the same time, during the sampling process, the sampling needle should always be in the liquid to be sucked, and its capacitance value should remain stable. If the amount of liquid is insufficient and air is sucked in, the detection of empty sampling can also be achieved by detecting the capacitance value during the sampling process.

[0068] Pressure detection circuit design Figure 3 .

[0069] The signal output by the pressure sensor is collected by a signal acquisition module and converted into an electrical signal (usually a voltage signal). The output electrical signal is amplified once by an amplifier and then filtered by an analog low-pass filter to remove interference signals. The filtered signal is then split into two paths for secondary amplification. The low-pressure channel has a higher amplification factor, resulting in a smaller detectable pressure signal range, but with higher signal resolution at low pressures. The high-pressure channel has a lower amplification factor, resulting in lower pressure signal detection resolution, but with a wider detectable range.

[0070] The control unit simultaneously collects signals from both channels and converts them into digital signals that can be recognized by the controller through an analog-to-digital conversion module. The control unit processes the signals using an internal algorithm to identify any pressure anomalies, which are then reported via the communication unit. Finally, the pressure data is stored in a storage unit for subsequent test data retrieval.

[0071] Capacitance detection circuit design Figure 4 .

[0072] During the movement of the sampling needle, there will be a change in the capacitance value of the body. After being collected by the signal acquisition circuit and filtered, it is input into the oscillator. The output signal frequency of the oscillator will change with the change of the capacitance signal. After the output frequency signal is divided by the frequency divider, it is input into the control unit counter to measure the frequency signal.

[0073] When the sampling needle enters or leaves the liquid surface, the capacitance value of the sampling needle will change. This changed capacitance value will cause the frequency of the output signal to change, thus generating a signal with a completely different frequency and inputting it into the control unit. By performing real-time processing on the signal through the internal algorithm of the control unit, it is possible to identify whether the sampling needle enters or leaves the liquid surface, and then report it through the communication unit.

[0074] The basic basis for detecting the sampling quality is the real-time pressure of the liquid path of the sampling needle.

[0075] The variation law of the liquid path pressure during the typical sampling process is as Figure 5 .

[0076] This process is divided into the following parts: the sampling needle touches the liquid surface; starting to sample, the pressure begins to decrease; when the syringe speed reaches the maximum, the pressure decreases to a certain level; when the syringe maintains a constant speed for sampling, the pressure will reach equilibrium (for some high-viscosity samples, the pressure will continue to drop); the syringe starts to decelerate and the pressure begins to recover; the sampling ends and returns to the static pressure.

[0077] First, define the following terms: initial pressure P0: the liquid path pressure before the start of sampling. Under normal circumstances, it is manifested as the hydrostatic pressure of the liquid in the pipeline; minimum pressure Pr: the real-time pressure during the sampling process; process pressure Pp: the pressure before the syringe decelerates (at the end of the constant speed section); end pressure Pend: the pressure after the sampling ends.

[0078] Data Processing

[0079] For relatively significant sampling anomalies (blockage or large-volume rapid sampling), differences can be clearly detected through pressure detection. However, when the sampling volume decreases or the speed slows down, the amplitude of the pressure change becomes smaller at this time. At the same time, due to the existence of system noise, it becomes difficult to detect pressure anomalies. This noise mainly comes from within the system, such as the operation of the pump, the vibration of the sample arm or pipeline, etc., as well as the vibration generated by the operation of other mechanical components outside the system. Therefore, to improve the reliability of pressure anomaly detection, it is necessary to remove these interference signals. It is measured that the frequency of this vibration signal is mainly in the range of >20Hz. Therefore, the interference noise can be filtered out by means of low-pass filtering (including analog low-pass filtering or digital low-pass filtering).

[0080] Figure 6 The pressure signals before and after the 20th-order 12Hz digital FIR low-pass filtering.

[0081] Pressure characteristics of needle clogging during the sampling process

[0082] When blockage occurs during the sampling process (such as sucking a clot), the variation law of the liquid path pressure is as follows Figure 7 . Compared with normal sampling, it has the following characteristics: (1) The amplitude of pressure change is related to the blockage, but generally greater than that during normal sampling; (2) After the sampling ends, the pressure cannot recover.

[0083] Therefore, it is possible to judge whether needle clogging occurs according to the magnitude of the pressure difference of the maximum pressure change amplitude P0 - Pr during the sampling process, and it is also possible to judge whether needle clogging occurs according to the pressure condition after sampling, that is, to judge whether needle clogging occurs according to the magnitude of the pressure difference of P0 - Pr.

[0084] In addition, in practical applications, due to the complexity of the sample to be aspirated, it may cause the aspiration of impurities but not completely block the sampling needle. For example, when the viscosity of the sample to be aspirated is too high, or small clots adhere to the inner wall of the sampling needle, etc. In this case, it will not cause the sampling needle to be completely blocked, but it will still cause abnormal sampling state and affect the accuracy of sampling and sample addition. For this situation, the variation law of the liquid path pressure is as follows Figure 8 As shown, after the sampling ends (at the red dotted line in the figure), the pressure cannot recover normally. In addition, the degree of partial blockage can also be estimated according to the pressure condition at this time.

[0085] Pressure characteristics of air aspiration during the sampling process

[0086] When no sample is aspirated at all (such as the sample is not placed, or the liquid level detection is incorrect), the variation law of the liquid path pressure is as follows Figure 9 . The characteristic is that the change amount of the sampling pressure is very small.

[0087] Therefore, it is possible to judge whether air aspiration occurs according to the magnitude of the pressure difference of the pressure change amplitude P0 - Pp during the sampling process, that is, whether air is completely aspirated.

[0088] When air aspiration occurs in the later stage of sampling (such as too little sample volume, or insufficient insertion depth), the variation law of the liquid path pressure is as follows Figure 10 . The pressure rises in the later stage of the uniform speed stage of the syringe. Similarly, it can be judged by the change amount of the pressure in this stage and the initial pressure, that is, it is possible to judge whether partial air aspiration occurs according to the magnitude of the pressure difference of the pressure change amplitude P0 - Pp during the sampling process. In addition, it can also be judged according to whether the pressure fluctuates in the uniform and stable stage, that is, the slope change of the pressure in the uniform and stable stage exceeds the threshold value. At the same time, it is possible to judge when air is aspirated and the proportion of the aspirated air according to the time point of the slope change.

[0089] In addition to insufficient sampling volume caused by insufficient sample, it is also possible that there are bubbles in the solution to be aspirated itself. When bubbles are aspirated, it will also cause insufficient sampling volume. At this time, the main pressure performance is as followsFigure 11 As shown, during the uniform sample aspiration process of the syringe, the pressure shows irregular fluctuations.

[0090] Based on the above abnormal characteristics, the complete pressure abnormal detection process for the sample aspiration needle during the sample aspiration process Figure 12 is shown as follows.

[0091] Pressure detection before cleaning and sample aspiration: In addition to detecting abnormalities during the sample aspiration process, pressure detection can also be performed on some preparation stages before sample aspiration. The sample analyzer usually performs cleaning before sample aspiration to remove carry-over contamination from the previous sample aspiration process, and inhales a small amount of air before sample aspiration to isolate the system fluid in the sample aspiration needle and the sample to be aspirated. The cleaning process and the process of inhaling isolation air can be detected, and abnormalities occurring during these processes can be identified to prevent related sample aspiration operations from being carried out when the system is already abnormal before sample aspiration.

[0092] Needle blockage during cleaning: The typical pressure change law of the liquid path during the cleaning process Figure 13 has the following characteristics: After opening the cleaning valve, the pressure of the liquid path rises rapidly; after closing the valve, the pressure quickly returns. The pressure change is very obvious.

[0093] The characteristic of the liquid path pressure when the needle is still blocked after cleaning is that after the cleaning is completed, the pressure cannot recover quickly but drops very slowly. Therefore, the real-time pressure can be detected after the cleaning is completed to determine whether needle blockage during cleaning occurs.

[0094] Needle blockage before sample aspiration: The sample aspiration needle usually aspirates a small amount of air before sample aspiration. If the needle is blocked at this time, its characteristics are similar to those of needle blockage during the sample aspiration process. Therefore, it is also possible to judge whether needle blockage before sample aspiration occurs by the pressure recovery situation after aspirating air. This system judges needle blockage during cleaning after the cleaning is completed, and the detection process is Figure 14 as shown. This system judges needle blockage before sample aspiration (after aspirating isolation air), and the detection process is Figure 15 as shown.

[0095] Capacitance (liquid level) detection: In terms of detecting needle blockage during sample aspiration pressure detection, due to the significant pressure change, it has relatively high accuracy and reliability in detecting needle blockage; while in terms of detecting air aspiration, if the air aspiration volume is very small, the pressure change difference is small, and there may be certain detection errors. Therefore, to improve its reliability, two combined measurement methods of pressure and capacitance can be used to detect air aspiration abnormalities.

[0096] Capacitance detection during sample aspiration process: The basic basis is the change of capacitance during the sample aspiration process, which reflects the environment where the sample aspiration needle is located during the sample aspiration process.

[0097] Capacitance characteristics of normal sample aspiration process: The typical capacitance change law during the sample aspiration process is as Figure 16 shown.

[0098] This process is divided into the following parts:

[0099] (1) The sampling needle descends to detect the liquid level. As the sampling needle gets closer and closer to the liquid to be aspirated, the capacitance value rises slowly;

[0100] (2) The sampling needle touches the liquid level, the capacitance value increases rapidly, and the liquid level is detected;

[0101] (3) The sampling needle stops descending;

[0102] (4) The injection pump starts to aspirate. During the aspiration process, to ensure sufficient aspiration, the sampling needle always remains below the liquid level, and at this time the capacitance value remains at a high level;

[0103] (5) The aspiration ends;

[0104] (6) The sampling needle is lifted out of the liquid level, and at this time the capacitance value drops rapidly and returns to the state in the air.

[0105] Capacitance characteristics of air aspiration during the sampling process: When air aspiration (insufficient sample, abnormal liquid level position, etc.) occurs during the sampling process, resulting in insufficient aspiration, the capacitance change rule is as Figure 17 . Compared with normal sampling, it has the following characteristics: Before the sampling process is completed, the sampling needle has already left the liquid level, resulting in an early drop in the capacitance value. Therefore, it is possible to judge whether an air aspiration event has occurred based on the timing of the event of the sampling needle leaving the liquid level (capacitance value drop). If it is detected that the sampling needle has left the liquid level before the sampling process is completed, it can be determined that abnormal air aspiration has occurred.

[0106] Abnormal detection process during the sampling process: Based on the above abnormal characteristics, the capacitance detection process related to the abnormality of the sampling needle during the sampling process is as Figure 18 shown.

[0107] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. An abnormal detection process for a liquid path system in sampling quality detection, characterized in that: The liquid path system includes a capacitance detection module, a syringe, a pressure detection module, a cleaning valve, a cleaning pump, a degassing module, and a water tank that are connected in sequence. The capacitance detection module, syringe, pressure detection module, cleaning valve, cleaning pump, degassing module, and water tank are connected by pipelines; The capacitance detection module includes a sampling needle that collects capacitance signals. Further, the collected capacitance signals are input to an oscillator after signal filtering. The frequency signal output by the oscillator is divided by a frequency divider and then input to a counter of the first control unit for frequency signal measurement. Further, the measured frequency signal is reported through the first communication unit; The pressure detection module includes a pressure sensor that collects signals and converts them into electrical signals. The collected signals are first amplified and then filtered by data. Further, they are simultaneously amplified a second time in the high-pressure channel and the low-pressure channel. The first analog-to-digital conversion module and the second analog-to-digital conversion module of the second control unit simultaneously collect and convert the electrical signals amplified a second time in the high-pressure channel and the low-pressure channel respectively, converting the analog electrical signals into digital signals, and judging whether a pressure abnormality occurs by identifying the digital signals; Further, the pressure data is reported through the second communication unit and stored in the storage unit; The abnormal detection process includes the following steps: Step 5: The sampling needle descends into the liquid surface, waits for a delay until the pressure is stable, and measures the initial pressure P0; Step 6: The syringe starts to sample, and the real-time pressure Pr during sampling is measured. When P0 - Pr > the needle blockage threshold, sampling ends and needle blockage is reported. When P0 - Pr ≤ the needle blockage threshold, the syringe is in the uniform speed section, waits for a delay until the real-time pressure is stable, and calculates the slope Kp of the pressure data in the uniform speed section at this time; Step 7: When the data fluctuation of Kp exceeds the limit, sampling ends and air bubble inhalation is reported. When the data fluctuation of Kp does not exceed the limit, it is judged whether the syringe starts to decelerate; Step 8: When the syringe does not start to decelerate, it is judged whether sampling is completed. If sampling is not completed, return to Step 6 and start Step 6 again; Step 9: When the syringe starts to decelerate, measure the real-time pressure Pp before deceleration. When P0 - Pp < the dry aspiration threshold, sampling ends and dry aspiration is reported. When P0 - Pp ≥ the dry aspiration threshold, it is judged whether sampling is completed. If sampling is not completed, return to Step 6 and start Step 6 again; Step 10: When it is judged that sampling is completed in Steps 8 and 9, the syringe stops and the end pressure Pend is measured. If P0 - Pend > the partial blockage threshold, partial blockage is reported. When P0 - Pend ≤ the partial blockage threshold, there is no abnormality in the liquid path.

2. The liquid path system for sampling quality detection according to claim 1, wherein: The sampling needle adopts a double-layer metal structure with an inner wall and an outer wall nested. The outer wall of the sampling needle is fixed on the sample arm moving component, and an insulating layer is provided between the inner wall and the outer wall of the sampling needle. A capacitance detection module is provided on the sample arm moving component, and the inner wall and the outer wall of the sampling needle are simultaneously connected to the signal input end of the capacitance detection module.

3. The liquid path system for sampling quality detection according to claim 1, characterized in that: The pressure sensor is installed vertically.

4. The liquid path system for sampling quality detection according to claim 1, wherein: The pressure sensor is installed between the cleaning valve and the syringe, and the pipeline between the pressure sensor and the syringe is ≤ 200 mm.

5. The liquid path system for sampling quality detection according to claim 1, characterized in that: The pipeline is a rigid pipe, and the movable part of the pipeline is U-shaped, and the U-shaped angles of the movable parts of several pipelines are the same.

6. The abnormal detection process of the liquid path system for sampling quality detection according to claim 1, characterized in that When the sampling needle has detected a sample, the sample of the sampling needle is replaced. Before replacing the new sample, the sampling needle is cleaned; during the cleaning process of the sampling needle, the situation of cleaning needle blockage is judged. The judgment of cleaning needle blockage includes the following steps: Step 1: Judge whether the cleaning is over: If the cleaning is not over, return to perform cleaning and judge whether the cleaning is over; if the cleaning is over, wait for a delay until the real-time pressure is stable. Step 2: If the real-time pressure P > the cleaning blockage threshold, end normally; if the real-time pressure P ≤ the cleaning blockage threshold, report cleaning needle blockage.

7. The abnormal detection process of the liquid path system for sampling quality detection according to claim 1 or 6, characterized in that, After the sampling needle is cleaned and before sampling at the same time, judge the needle blockage situation of the sampling needle. The steps of judging needle blockage are as follows: Step 3: Judge whether the inhalation of isolated air is over: If the inhalation of isolated air is not over, return to end the inhalation of isolated air again. If the inhalation of isolated air is over, judge whether the pressure P < the normal recovery pressure holds. Step 4: If the pressure P < the normal recovery pressure, end normally. If the pressure P ≥ the normal recovery pressure, report needle blockage before sampling.

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