Liquid path system for sample suction quality detection and anomaly detection process

Abstract

The invention belongs to the technical field of biological liquid sample detection, and particularly relates to a liquid path system for sample suction quality detection and an anomaly detection process. A liquid path system for sample suction quality detection comprises a capacitance detection module, an injector, a pressure detection module, a cleaning valve, a cleaning pump, a degassing module and a water tank which are connected in sequence, and the capacitance detection module, the injector, the pressure detection module, the cleaning valve, the cleaning pump, the degassing module and the water tank are connected through pipelines. The method mainly solves the following problems: 1, the contradiction between the pressure monitoring range and the monitoring resolution; 2, when the sample is insufficient or bubbles are sucked, the difference between the suction pressure and the normal liquid suction pressure is small, so that misjudgment is easily caused; 3, misjudgment is easily caused by noise signal interference; 4, corresponding error monitoring mechanisms are lacked in other processes such as cleaning, sample adding and the like; and 5, monitoring is performed by excessively depending on a single mode, and the pressure is easily interfered in the testing process.

Description

Technical Field

[0001] 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. Background Art

[0002] In Vitro Diagnostic Devices (IVD) refer to medical devices that detect and analyze human samples (such as blood, urine, tissue fluid, etc.) 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 various types of in vitro diagnostic instruments, which can be classified into large categories such as biochemical analyzers, immunoassays, hematology analyzers, molecular diagnostic instruments, microbial detectors, coagulation analyzers, urine analyzers, POCT (Point-of-Care Testing) devices, etc., according to different detection principles, target analytes, and application scenarios.

[0003] Currently, the development trend of in vitro diagnostic instruments is high speed, high precision, and high automation. The accuracy and speed of the sample addition process are one of the main factors affecting the performance of the instrument. As the sample volume required for a single test becomes smaller and smaller, the requirement for the accuracy of sample addition is also getting higher and higher. During the sample addition process, any interference or deviation may lead to incorrect test results. Therefore, it is particularly important to implement effective status monitoring of the sample addition process to ensure accurate liquid transfer and addition of samples or reagents during the test.

[0004] In practical applications, due to the complexity of the samples to be transferred, it is easy to cause deviations in sampling and sample addition. Typical problems include: sampling needle blockage, insufficient samples, bubble interference, etc.

[0005] Currently, the means for monitoring the quality of sample transfer mainly monitor 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 and rinsed during cleaning to ensure thorough rinsing, the cleaning pressure is relatively large (generally several hundred kilopascals), so the monitoring and pressure resistance range requirements of the pressure sensor are relatively large. During the sample aspiration process, as the sample volume becomes less and less, for the aspiration process of a small amount of liquid, the pressure change is relatively small (several kilopascals). Therefore, the pressure sensor is required to have high monitoring accuracy and resolution for the low-pressure part; 2. Currently, pressure monitoring is mainly used for needle blockage monitoring with high accuracy and reliability because the suction pressure during needle blockage is quite different from the normal liquid suction pressure, and it is not easy 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, which is prone to misjudgment; 3. When the aspirated sample volume is small, due to the low suction speed or short suction 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 disadvantages of detecting pressure changes 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: 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; The capacitance detection module includes an aspiration needle, and the aspiration needle 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 a first control unit for frequency signal measurement; further, the measured frequency signal is reported through a first communication unit; The pressure detection module includes a pressure sensor which collects signals and converts them into electrical signals. The collected signals are first amplified and then filtered, and further amplified twice in the high-pressure channel and the low-pressure channel simultaneously. 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 twice 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 occurs. Further, the pressure data is reported through the second communication unit and stored in the storage unit.

[0009] 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 assembly, 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 assembly, 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.

[0010] Preferably, the pressure sensor is installed vertically.

[0011] Preferably, the pressure sensor is installed between the cleaning valve and the syringe, and the pipeline between the pressure sensor and the syringe is ≤200mm.

[0012] 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.

[0013] An abnormal detection process for a liquid path system for detecting sampling quality includes the following steps: Step 5: The sampling needle probes into the liquid surface and waits for a delay until the pressure is stable, and the initial pressure P0 is measured. 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 a 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 an 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 air aspiration threshold, sampling ends and an air aspiration is reported. When P0 - Pp ≥ the air 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 determined in Steps 8 and 9 that the sample aspiration is completed, 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, there is no abnormality in the liquid path.

[0014] Preferably, after the sampling needle detects one sample, the sample of the sampling needle is replaced, and before replacing the new sample, the sampling needle is cleaned; during the cleaning process of the sampling needle, the cleaning needle blockage situation is judged, and the cleaning needle blockage judgment includes the following steps: Step 1: Determine whether the cleaning is completed: If the cleaning is not completed, return for cleaning and determine whether the cleaning is completed; if the cleaning is completed, delay and wait for the real-time pressure to stabilize; 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.

[0015] Preferably, before sampling and after the sampling needle is cleaned, the needle blockage situation of the sampling needle is judged, and the steps of needle blockage judgment are as follows: Step 3: Determine whether the aspiration of isolated air is completed: If the aspiration of isolated air is not completed, return to re-complete the aspiration of isolated air; if the aspiration of isolated air is completed, judge whether the pressure P < the normal recovery pressure is established; 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.

[0016] Preferably, the detection steps for abnormal capacitance during the sampling process are as follows: (1) The sampling needle descends to the liquid level. If the liquid level is detected, start sampling; (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 lift the sampling needle; if not, judge whether the sampling is completed; (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, lift the sampling needle and further detect whether the sampling needle is separated from the liquid level; (4) If the sampling needle is separated from the liquid level, end normally; if the sampling needle is not separated from the liquid level, report abnormal liquid level separation.

[0017] Compared with the prior art, the beneficial effects of the present invention are: (1) In the liquid circuit system for sample aspiration quality detection provided by the present invention, the pressure sensor is installed vertically to facilitate the discharge of bubbles; the pipeline should use a hard tube to reduce the fluctuation of the pipeline itself, and the pipeline should be fixed to minimize the shaking of the pipeline during the operation of the sample arm; the pipeline needs to have an upper and lower movable part, adopt a U-shaped method, and ensure that the U-shaped angle is consistent during operation; the length of the pipeline from the sample aspiration needle to the syringe should not be too long, and bending, winding, switching and diameter change should be avoided (minimized); the pipeline should not be too thin, which will increase the resistance along the pipeline section and amplify the pressure fluctuation of the pipeline; (2) The present invention provides a liquid circuit system for sample aspiration quality detection, wherein the sample aspiration needle adopts a double-layer metal structure with an inner wall and an outer wall nested, the outer wall of the sample aspiration 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 sample aspiration needle; a capacitance detection module is provided on the sample arm moving component, and the inner wall and the outer wall of the sample aspiration needle are simultaneously connected to the signal input end of the capacitance detection module; the capacitance detection module can determine the current environment of the sample aspiration needle (in the air or in the liquid) by detecting the capacitance between the inner and outer walls of the needle, thereby realizing the liquid surface contact detection of the sample aspiration needle; the control unit controls the movement of the sample arm through the driving unit to realize the movement of the sample aspiration needle to detect the liquid surface, when the needle contacts the liquid surface, 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, thereby realizing accurate liquid surface detection; during the sample aspiration process, the sample aspiration needle should always be in the liquid to be aspirated, and its capacitance value should remain stable. If the amount of liquid is insufficient and air is aspirated, the detection of empty aspiration can also be realized by detecting the capacitance value during the sample aspiration process; (3) The present invention provides a liquid circuit system for sample aspiration quality detection, which has a dual-channel design for the pressure detection module, so that the same pressure sensor can monitor both high and low pressure channels at the same time. The high-pressure channel ensures the high-pressure monitoring range of processes such as cleaning and needle blocking, while the low-pressure channel ensures the detection resolution of small pressure differences in processes such as aspiration of a small amount of sample; (4) The present invention provides a liquid circuit system for sample suction quality detection. The sample suction needle will have a change in the capacitance value during the movement. After passing through the signal acquisition circuit and filtering, it is input to the oscillator. The output signal frequency of the oscillator will change with the change of the capacitance signal. The output frequency signal is divided by the frequency divider and input to the control unit counter to measure the frequency signal. When the sample suction needle enters or leaves the liquid surface, the capacitance value of the needle will change. This change in 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. The signal is processed in real time by the internal algorithm of the control unit to identify whether the sample suction needle enters or leaves the liquid surface, and then reported through the communication unit. Since the slight change in capacitance value is difficult to be detected by the control unit, this solution directly converts the change in capacitance value into the frequency change of the electrical signal, and uses the advantage of the control unit's accurate counting to make the control unit's judgment more accurate. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a connection diagram of the liquid circuit system of the present invention; Figure 2 This is the connection diagram of the sampling needle capacitance detection module; Figure 3 It is a structural schematic diagram of the pressure detection module of the present invention; Figure 4 It is a structural schematic diagram of the capacitance detection module of the present invention; Figure 5 This is the real-time pressure change curve of the liquid circuit during the normal sampling process; Figure 6 It is the real-time pressure signal before and after 20th-order 12Hz digital FIR low-pass filtering; Figure 7 This is the pressure change curve when the sampling needle is completely blocked during sampling; Figure 8 This is the pressure change curve when the sampling needle is partially blocked during sampling; Figure 9 This is the pressure change curve when the sample aspiration needle does not aspirate the sample at all; Figure 10 The pressure curve of partial air suction with different proportions (actual water absorption / target water absorption); Figure 11 is the suction bubble pressure curve; Figure 12 It is a complete process for detecting abnormal pressure during the sampling process of the sampling needle; Figure 13 It is the pressure change curve of the cleaning process; Figure 14 To clean the blocked needle detection process; Figure 15 This is the needle blockage detection process before aspiration; Figure 16 The capacitance changes during the normal sampling process; Figure 17 It is the capacitance change during abnormal sampling process; Figure 18 This is the flow chart of capacitance anomaly detection in the sampling process. DETAILED DESCRIPTION

[0019] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] The liquid path structure related to the analyzer sample aspiration needle is as follows Figure 1 .

[0021] The cleaning pump is responsible for providing cleaning pressure for the inner wall of the needle. The cleaning valve corresponding to the needle that needs to be cleaned is opened during cleaning, and cleaning water flows out from the inner wall of the needle. During aspiration and discharge, the cleaning valve remains closed, and the syringe completes sample aspiration and discharge. The pressure detection module is installed between the cleaning valve and the aspiration needle, where both the cleaning pressure and the aspiration and discharge pressure can be detected.

[0022] During cleaning, the pressure of the entire aspirating needle liquid path changes greatly, so there is no special requirement for the sensor installation position; during aspirating, the pressure of the aspirating needle liquid path changes slightly, so the sensor needs to be installed in the pressure-sensitive part. Since the syringe is the source of pressure change when the aspirating needle aspirates, the sensor should be placed near the syringe.

[0023] Bubbles have a certain elasticity, and their presence will affect the change law of liquid circuit pressure, and generally cause false detection of empty suction. The presence of bubbles in liquid circuit components such as needles, pipes, pressure sensors, and syringes must be avoided, so a degassing module is very necessary.

[0024] In addition, the vibration of the pump, pipeline and sensor will cause abnormal pressure fluctuations and cause false detection of empty suction. The vibration of the liquid circuit components should be avoided.

[0025] 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.

[0026] Capacitance detection structure such as Figure 2 shown.

[0027] The sampling needle adopts a double-layer metal structure with inner and outer nesting. The outer wall of the needle is fixed on the moving component of the sample arm. An insulating design is adopted between the inner and outer layers. Therefore, 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 that is also fixed on the moving component. By detecting the capacitance between the inner and outer walls of the needle, the capacitance detection module can determine the current environment where the sampling needle is located (in the air or in the liquid), so as to realize the liquid surface contact detection of the sampling needle.

[0028] 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 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 driving unit to stop moving, thus realizing accurate liquid surface detection.

[0029] At the same time, 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, by detecting the capacitance value during the sampling process, the detection of air aspiration during sampling can also be realized.

[0030] The pressure detection circuit is designed as Figure 3 .

[0031] The signal output by the pressure sensor is collected by the 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 data filtering is performed through an analog low-pass filter to remove interference signals. The filtered signal is divided into two paths for secondary amplification. The low-pressure channel has a higher amplification factor, and its detectable pressure signal range is smaller, but the signal resolution is higher at low pressure; while the high-pressure channel signal has a lower amplification factor, its detectable resolution of the pressure signal is lower, but the detectable range of the signal is larger.

[0032] The control unit simultaneously collects the signals of the two channels and converts the analog signals into digital signals that can be recognized by the controller through the analog-to-digital conversion module. Through the internal algorithm of the control unit to process the signals, whether there is a pressure abnormality can be identified and reported through the communication unit. Finally, the pressure data is stored in the storage unit for subsequent acquisition of test data.

[0033] The capacitance detection circuit is designed as Figure 4 .

[0034] During the movement of the sampling needle, there will be a change in the capacitance value of the body. After passing through the signal acquisition circuit and filtering, it is input to the oscillator. The output signal frequency of the oscillator will change with the change of the capacitance signal. The output frequency signal is divided by the frequency divider and then input to the counter of the control unit to measure the frequency signal.

[0035] When the sample needle enters or leaves the liquid surface, the capacitance value of the sample needle will change. This change in capacitance value will change the frequency of the output signal, thus generating a signal with a completely different frequency and inputting it into the control unit. The control unit processes the signal in real time through the internal algorithm of the control unit to identify whether the sample needle enters or leaves the liquid surface, and then reports it through the communication unit.

[0036] The basic basis for sampling quality detection is the real-time pressure of the sampling needle liquid path.

[0037] The change law of liquid pressure in a typical sampling process is as follows: Figure 5 .

[0038] The process is divided into the following parts: the sample suction needle touches the liquid surface; sample suction begins and the pressure begins to decrease; when the syringe speed reaches the maximum, the pressure drops to a certain level; the syringe maintains a constant speed of suction and the pressure will reach equilibrium (the pressure of some high-viscosity samples will continue to drop); the syringe begins to decelerate and the pressure begins to recover; sample suction ends and the pressure returns to the static pressure.

[0039] First, define the following terms: initial pressure P0: the pressure in the liquid circuit before the start of sample aspiration. Under normal circumstances, it is expressed as the hydrostatic pressure of the liquid in the pipeline; minimum pressure Pr: the real-time pressure during sample aspiration; process pressure Pp: the pressure before the syringe decelerates (at the end of uniform speed); end pressure Pend: the pressure after the end of sample aspiration.

[0040] Data processing For more significant sampling anomalies (blockage or large volume and fast sampling), the difference can be clearly found through pressure detection, but when the sampling volume decreases or the speed slows down, the pressure change amplitude becomes smaller, and the presence of system noise makes pressure anomaly detection difficult. This noise mainly comes from inside the system, such as the operation of the pump, the vibration of the sample arm or pipeline, and the vibration generated by the operation of other mechanical parts outside the system. Therefore, in order to improve the reliability of pressure anomaly detection, these interference signals need to be removed. The measured frequency of the vibration signal is mainly in the range of >20Hz, so the interference noise can be filtered out by low-pass filtering (including analog low-pass filtering or digital low-pass filtering).

[0041] Figure 6 These are the pressure signals before and after 20th-order 12Hz digital FIR low-pass filtering.

[0042] Pressure characteristics of needle blocking during sampling process When a blockage occurs during the aspiration process (such as a clot), the pressure change pattern of the liquid path is as follows: Figure 7 Compared with normal suction, it has the following characteristics: (i) The pressure change amplitude is related to the blockage, but is generally greater than that of normal suction; (ii) After the suction is completed, the pressure cannot be restored. Therefore, it is possible to judge whether a needle clogging occurs based on the magnitude of the pressure difference between the maximum pressure change range P0 - Pr during the sampling process, or to judge whether a needle clogging occurs according to the pressure condition after sampling, that is, to judge whether a needle clogging occurs based on the magnitude of the pressure difference of P0 - Pr.

[0043] In addition, in practical applications, due to the complexity of the sample to be aspirated, it may cause the aspiration of impurities without completely blocking 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 law of liquid path pressure change is as Figure 8 shown. After the sampling is completed (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.

[0044] Pressure characteristics of air aspiration during the sampling process When no sample is aspirated at all (such as the sample is not placed, or the liquid level detection is incorrect), the law of liquid path pressure change is as Figure 9 . The characteristic is that the change amount of the sampling pressure is very small.

[0045] Therefore, it is possible to judge whether air aspiration occurs, that is, complete air inhalation, based on the magnitude of the pressure difference between the pressure change range P0 - Pp during the sampling process.

[0046] When air aspiration occurs in the later stage of sampling (such as too little sample volume, or insufficient insertion depth), the law of liquid path pressure change is as Figure 10 . 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 based on the magnitude of the pressure difference between the pressure change range P0 - Pp during the sampling process. In addition, it can also be judged according to whether the pressure in the uniform and stable section fluctuates, that is, the slope change of the pressure in the uniform and stable section exceeds the threshold. At the same time, it is possible to judge when air is inhaled and the proportion of inhaled air according to the time point of the slope change.

[0047] 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 inhaled, it will also cause insufficient sampling volume. At this time, the main pressure performance is as Figure 11 shown. During the uniform sampling process of the syringe, the pressure shows irregular fluctuations.

[0048] Based on the above abnormal characteristics, the complete pressure anomaly detection process for the sampling needle during the sampling process Figure 12 is shown.

[0049] Pressure Detection before Cleaning and Sampling: In addition to detecting abnormalities during the sampling process, pressure can also be detected during some preparation stages before sampling. Before sampling, the sample analyzer usually performs cleaning to remove carry-over contamination from the previous sampling process and inhales a small amount of air before sampling to isolate the system fluid in the sampling needle from 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 sampling operations from being carried out when abnormalities already exist before sampling.

[0050] Needle Blockage during Cleaning: Typical Variation Law of Liquid Path Pressure during the Cleaning Process Figure 13 . It has the following characteristics: After opening the cleaning valve, the liquid path pressure rises rapidly; after closing the valve, the pressure quickly returns. The pressure change is very obvious.

[0051] The characteristic of the liquid path pressure when the needle is still blocked after cleaning is that after the cleaning ends, the pressure cannot quickly recover but drops very slowly. Therefore, the real-time pressure can be detected after the cleaning ends to determine whether needle blockage during cleaning occurs.

[0052] Needle Blockage before Sampling: Before sampling, the sampling needle usually aspirates a small amount of air first. If the needle is blocked at this time, its characteristics are similar to those of needle blockage during the sampling process. Therefore, it is also possible to judge whether needle blockage before sampling occurs by the pressure recovery situation after aspirating air. This system judges needle blockage during cleaning after the cleaning ends, and the detection process is Figure 14 as shown. This system judges needle blockage before sampling (after inhaling isolation air), and the detection process is Figure 15 as shown.

[0053] Capacitance (Liquid Level) Detection: In terms of needle blockage detection during sampling, due to the significant pressure change, it has relatively high accuracy and reliability in detecting needle blockage; while in terms of air aspiration detection, 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, pressure and capacitance can be used simultaneously in two combined measurement methods to detect air aspiration abnormalities.

[0054] Capacitance Detection during Sampling Process: The basic basis is the change in capacitance during the sampling process, which reflects the environment where the sampling needle is located during the sampling process.

[0055] Capacitance Characteristics of Normal Sampling Process: Typical Variation Law of Capacitance during the Sampling Process is as Figure 16 shown.

[0056] This process is divided into the following parts: (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 slowly rises; (2) The sampling needle touches the liquid level, and the capacitance value increases rapidly, detecting the liquid level; (3)The sampling needle stops descending; (4)The injection pump starts sampling. During the sampling process, to ensure sufficient sampling, the sampling needle always remains below the liquid level, and at this time, the capacitance value remains at a high level; (5)Sampling ends; (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 air.

[0057] 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 sampling, the capacitance change rule is as Figure 17 . Compared with normal sampling, it has the following characteristics: Before the sampling process ends, 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 ends, it can be determined that abnormal air aspiration has occurred.

[0058] 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.

[0059] 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 principle and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A liquid path system for sample suction quality detection, characterized in that: It includes a capacitance detection module, a syringe, a pressure detection module, a cleaning valve, a cleaning pump, a degassing module and a water tank which are connected in sequence, wherein 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 capacitance detection module includes a sample suction needle, and the sample suction needle collects capacitance signals; further, the collected capacitance signals are input into an oscillator after signal filtering; the frequency signal output by the oscillator is divided by a frequency divider and then input into 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, which collects signals and converts them into electrical signals. The collected signals are amplified and filtered once, and then amplified twice in the high-pressure channel and the low-pressure channel at the same time. The first analog-to-digital conversion module and the second analog-to-digital conversion module of the second control unit collect and convert the electrical signals amplified twice in the high-pressure channel and the electrical signals amplified twice in the low-pressure channel at the same time, respectively, and convert the analog electrical signals into digital signals. By identifying the digital signals, it is determined whether pressure abnormality occurs. Furthermore, the pressure data is reported through the second communication unit, and the pressure data is stored in the storage unit.

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

3. A liquid path system for sample suction quality detection according to claim 1, characterized in that: The pressure sensor is installed in a vertical manner.

4. A liquid path system for sample suction quality detection according to claim 1, characterized in that: The pressure sensor is installed between the cleaning valve and the syringe, and the pipeline between the pressure sensor and the syringe is ≤200mm.

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

6. An abnormality detection process of a liquid path system for sample suction quality detection according to claim 1, characterized in that: The following steps are involved: Step 5: The sample suction needle goes down into the liquid surface, waits for the pressure to stabilize, and measures the initial pressure P0; Step 6: The syringe starts to aspirate the sample, and the real-time pressure position Pr of the aspirated sample is measured; when P0-Pr>needle blocking threshold, the aspirated sample is terminated and the needle blocking is reported; when P0-Pr≤needle blocking threshold, the syringe is placed in the uniform speed section, and a delay is made to wait for the real-time pressure to stabilize, and the slope Kp of the pressure data in the uniform speed section is calculated at this time; Step 7: When the Kp data fluctuation exceeds the limit, the sample suction is terminated and the suction bubble is reported; when the Kp data fluctuation does not exceed the limit, it is determined whether the syringe starts to decelerate; Step 8: When the syringe does not start to slow down, determine whether the sample aspiration is completed; if the sample aspiration is not completed, return to step 6 and restart step 6; Step 9: When the syringe starts to decelerate, measure the real-time pressure Pp before deceleration; When P0-Pp<empty suction threshold, the sampling is terminated and empty suction is reported; When P0-Pp≥empty suction threshold, determine whether the sample suction is completed. If the sample suction is not completed, return to step 6 and restart step 6; Step 10: When it is determined in steps 8 and 9 that the sample aspiration is completed, the syringe stops and the end pressure Pend is measured; If P0-Pend>partial blockage threshold, partial blockage is reported; when P0-Pend≤partial blockage threshold, there is no abnormality in the liquid circuit.

7. The abnormality detection process of the liquid path system for sample suction quality detection according to claim 6 is characterized in that ,After the sampling needle detects 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 cleaning needle blockage situation is judged, and the cleaning needle blockage judgment includes the following steps: Step 1: Determine whether the cleaning is finished: If the cleaning is not finished, return to clean and determine whether the cleaning is finished; if the cleaning is finished, delay and wait for the real-time pressure to stabilize; Step 2: If the real-time pressure P>cleaning blockage threshold, the process ends normally; if the real-time pressure P≤cleaning blockage threshold, a cleaning needle blockage is reported.

8. The abnormality detection process of the liquid path system for sample suction quality detection according to claim 6 or 7, characterized in that: After cleaning the sample aspiration needle and before aspiration, the blockage of the sample aspiration needle is judged. The steps for judging the blockage are as follows: Step 3: Determine whether the isolation air suction is completed: if the isolation air suction is not completed, return to end the isolation air suction again; If the isolation air suction is completed, it is determined whether the pressure P < normal recovery pressure is established; Step 4: If the pressure P is less than the normal recovery pressure, the process ends normally; If the pressure P ≥ normal recovery pressure, it will be reported that the needle is blocked before aspiration.

Images