Liquid level detection method and capacitive liquid level detection device

Abstract

This application discloses a liquid level detection method, a capacitive liquid level detection device, and an in vitro diagnostic (IVD) device. The liquid level detection method is based on a capacitive liquid level detection device, which includes a probe, a capacitive sensor, a first control module, and a second control module. The capacitive sensor converts changes in the liquid level of the probe, the liquid filling the probe, and the liquid contacted by the probe into changes in equivalent capacitance. The liquid level detection method includes: the first control module controlling the probe to move downwards from an initial position to approach the liquid in the container; during the probe's descent, the capacitive sensor detects changes in the probe's capacitance at preset intervals and sends this as detection data to the second control module. Utilizing the embodiments of this application can improve the response speed and accuracy of liquid level detection results.

Description

Technical Field

[0001] This invention relates to the field of industrial measurement technology, and in particular to a liquid level detection method, a capacitive liquid level detection device, an in vitro diagnostic (IVD) device, and a computer-readable storage medium. Background Technology

[0002] In vitro diagnostic (IVD) equipment is a type of in vitro diagnostic product, generally used as medical devices and electronic diagnostic instruments for testing various clinical specimens. With the rapid development of biotechnology and electronic technology, IVD diagnostic equipment has gradually evolved from semi-automatic to fully automatic, and from low-speed to high-speed. Simultaneously, liquid level detection has become an indispensable function in fully automated IVD diagnostic equipment. Specifically, during reagent or sample addition and pipetting, liquid level detection is required to determine whether the aspiration probe has picked up the reagent or sample, serving as the basis for the system to proceed to the next step.

[0003] Currently, capacitive level measurement is commonly used in in vitro diagnostic (IVD) devices. However, during use, probes in IVD devices often experience issues such as probe penetration (leading to impact) and excessive fluid accumulation, resulting in contamination. Furthermore, due to the thinness of the probes and the small size of the sample cups in IVD devices, the high sensitivity of capacitive level detection devices makes them susceptible to external interference, compromising the accuracy of level measurement results. Incorrect detection results can affect subsequent reagent or sample testing by the IVD device, potentially leading to erroneous clinical diagnostic information. Currently, no effective solutions have been found to address these problems in the technology. Summary of the Invention

[0004] To address the technical problems existing in the prior art, this invention proposes a liquid level detection method, a capacitive liquid level detection device, an in vitro diagnostic (IVD) device, and a computer-readable storage medium to solve at least one of the aforementioned technical problems.

[0005] This application proposes a liquid level detection method based on a capacitive liquid level detection device. The capacitive liquid level detection device includes a probe, a capacitive sensor, a first control module, and a second control module. The capacitive sensor converts the changes in the liquid level of the probe, the liquid filling the probe, and the liquid contacted by the probe into changes in the equivalent capacitance value. The liquid level detection method includes: the first control module controlling the probe to move downwards from an initial position to approach the liquid in the container; during the probe's descent, the capacitive sensor detects the changes in the probe's capacitance value at preset intervals and sends this detection data to the second control module; the second control module processes the acquired detection data... The dynamic average filtering process obtains the average value of the detected data within multiple filtering segments. The difference between each average value and the corresponding detected data within each filtering segment is then calculated. These differences are compared with preset steady-state thresholds to determine if the detected data within each filtering segment is steady-state data. If it is steady-state data, the average value of the corresponding filtering segment is taken as the steady-state mean. The second control module compares the change between the current steady-state mean and the previous steady-state mean with a preset liquid level detection threshold to determine if the probe has contacted the liquid surface. When it is determined that the probe has contacted the liquid surface, the second control module sends an interrupt signal to the first control module, causing the first control module to stop the probe from moving.

[0006] Optionally, the method further includes: before the probe reaches the container opening, the first control module controls the probe to accelerate; after the probe enters the container opening, the first control module controls the probe to decelerate until the speed decreases to a preset value, and then the first control module controls the probe to move at a constant speed until the interrupt position, and then the speed gradually decreases to zero, wherein the interrupt position is the position of the probe when the first control module receives the interrupt signal.

[0007] Optionally, the second control module compares the change between the current steady-state mean and the previous steady-state mean with a preset liquid level detection threshold to determine whether the probe is in contact with the liquid surface, including: if the difference between the current steady-state mean and the previous steady-state mean is greater than the liquid level detection threshold, then it is determined that the probe is in contact with the liquid surface; if the difference between the current steady-state mean and the previous steady-state mean is less than the liquid level detection threshold, then it is determined that the probe is not in contact with the liquid surface.

[0008] Optionally, determining whether the detection data in each filter segment is steady-state data includes: if the difference between all detection data in the filter segment and the corresponding average value is less than the steady-state threshold, then the data in the filter segment is determined to be steady-state data; and / or, if no more than M detection data in the filter segment have a difference between the corresponding average value and the steady-state threshold greater than the steady-state threshold, then the data in the filter segment is determined to be steady-state data.

[0009] Optionally, the method further includes: pre-configuring parameters in the second control module, the parameters including at least one of the following: moving average filter coefficient, steady-state threshold, exemption coefficient M and liquid level detection threshold, wherein the configured parameter values ​​are determined after multiple tests.

[0010] This application also proposes a capacitive liquid level detection device, including: a probe, a capacitive sensor, a first control module, and a second control module. The capacitive sensor is electrically connected to the probe and is used to monitor the liquid level change of the probe, the liquid filled in the probe, and the liquid contacted by the probe, and converts the liquid level change into a capacitance change and sends it to the second control module, so that the first control module and the second control module can perform the method described above.

[0011] Optionally, the capacitive sensor is an FDC2112 chip, and the liquid level detection device also includes an oscillation circuit. By adjusting the value of the inductance or capacitance of the oscillation circuit, as well as adjusting the switching time of the internal register of the FDC2112 chip and the value of the reference frequency division coefficient, the sampling rate can meet the requirements of measurement accuracy.

[0012] Optionally, the capacitive sensor is an FDC2112 chip, which uses an external clock as a reference clock. The liquid level detection device includes a P1 port, which is connected to the probe housing and the grounding electrode on the probe assembly. The interfaces I2C1_SDA, I2C1_SCL, INTB, and SD of the FDC2112 chip are connected to the second control module in the liquid level detection device. The I2C1_SDA and I2C1_SCL interfaces are used for configuring the FDC2112 chip and transmitting measurement data. The SD interface is used to set the power-off mode to save current. The interrupt pin INTB is used to notify the second control module of the completion of a data conversion.

[0013] This application also proposes an in vitro diagnostic (IVD) device, including the liquid level detection device as described above, wherein the probe is a probe in the IVD device, and the first control module is a motor controller in the IVD device.

[0014] This application also proposes a computer-readable storage medium storing computer program instructions that, when executed by a processor, implement the method described above.

[0015] This application embodiment, through processing the detection data, can obtain a relatively accurate steady-state mean value for determining whether the probe is in contact with the liquid surface. Since the steady-state mean represents the average value of steady-state data within the filtering segment, the difference between the current steady-state mean and the previous steady-state mean can yield the change in the steady-state mean. Furthermore, because the steady-state mean is related to the liquid level, changes in the steady-state mean can also reflect changes in the liquid level within the probe. Therefore, by setting a liquid level detection threshold, the determination of whether the probe is in contact with the liquid surface can be based on the current steady-state mean and the liquid level detection threshold. This application embodiment features a simple and efficient data processing process with low hardware requirements, facilitating implementation and application. Moreover, this method eliminates the influence of external structural components on the final test results, significantly improving the response speed and accuracy of liquid level detection. Attached Figure Description

[0016] The preferred embodiments of the present invention will now be described in further detail with reference to the accompanying drawings, wherein:

[0017] Figure 1 This is a flowchart of the liquid level detection method according to an embodiment of this application;

[0018] Figure 2 A schematic diagram of the liquid level detection principle of the capacitive liquid level detection device according to an embodiment of this application is shown;

[0019] Figure 3 This is a schematic diagram illustrating the principle of liquid level detection threshold determination according to an embodiment of this application;

[0020] Figure 4 This invention provides a schematic diagram illustrating the velocity change during the movement of the probe in an embodiment of this application.

[0021] Figure 5 A flowchart illustrating the data processing procedure of an embodiment of this application is shown;

[0022] Figure 6 A schematic diagram showing the test results obtained using the liquid level detection method according to an embodiment of this application is illustrated.

[0023] Figure 7 The schematic diagram of the FDC2112 liquid level detection principle is shown. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] In the following detailed description, reference can be made to the accompanying drawings, which form part of this application and illustrate specific embodiments of the present application. In the drawings, similar reference numerals describe substantially similar components in different figures. Specific embodiments of the present application are described in sufficient detail below to enable those skilled in the art to implement the technical solutions of the present application. It should be understood that other embodiments may also be utilized, or structural, logical, or electrical changes may be made to the embodiments of the present application.

[0026] In this document, terms such as first, second, and third are used only to distinguish one entity (or operation) from another, and are not intended to require or imply any order or relationship between these entities (or operations).

[0027] This application proposes a liquid level detection method based on a capacitive liquid level detection device. The capacitive liquid level detection device includes a probe, a capacitive sensor, a first control module, and a second control module. The capacitive sensor can convert the liquid level changes of the probe, the liquid filling the probe, and the liquid contacted by the probe into changes in equivalent capacitance. Figure 1 This is a flowchart of a liquid level detection method according to an embodiment of this application. The method includes the following steps:

[0028] S101: The first control module controls the probe to move down from its initial position to approach the liquid in the container.

[0029] S102: During the probe descent, the capacitance sensor detects the change in the probe's capacitance value at a preset cycle and sends it as detection data to the second control module.

[0030] S103: The second control module performs moving average filtering on the acquired multiple detection data to obtain the average value of the detection data in multiple filtering segments, obtains the difference between each average value and each detection data in the corresponding filtering segment, and compares the obtained multiple differences with the preset steady-state threshold to determine whether the detection data in each filtering segment is steady-state data. If it is steady-state data, the average value of the corresponding filtering segment is taken as the steady-state mean.

[0031] S104: The second control module compares the change between the current steady-state mean and the previous steady-state mean with a preset liquid level detection threshold to determine whether the probe has contacted the liquid surface; wherein, when it is determined that the probe has contacted the liquid surface, the second control module sends an interrupt signal to the first control module so that the first control module controls the probe to stop moving.

[0032] For ease of understanding, Figure 2A schematic diagram illustrating the liquid level detection principle of a capacitive liquid level detection device according to an embodiment of this application is shown. Figure 2 As shown, the capacitive liquid level detection device 100 includes a probe 101, a capacitive sensor, a first control module 104, and a second control module. The first control module 104 is connected to the second control module and is capable of data transmission. In some embodiments of this application, optionally, the capacitive sensor and the second control module are placed on the liquid level detection plate 106. The capacitive sensor is connected to both the probe and the second control module. The capacitive sensor can convert the changes in the liquid level of the probe 101, the liquid filling the probe, and the liquid contacted by the probe into changes in the equivalent capacitance value. Its measurement principle is that the probe and the ground act as the two plates of a capacitor, the liquid filling the probe acts as the dielectric, and the changes in the liquid level of the liquid contacted by the probe represent changes in the conductive medium. These changes in the conductive medium cause changes in the capacitance value. In this embodiment of the application, the capacitance sensor detects the changes in these capacitance values ​​as detection data and sends them to the second control module. The second control module processes the acquired detection data to obtain a steady-state average value. Then, the current steady-state average value is subtracted from the previous steady-state average value, and the difference is used as the final value to determine whether the probe is in contact with the liquid surface. The final value is then compared with a preset liquid level detection threshold to determine whether the probe is in contact with the liquid surface.

[0033] Additionally, see also Figure 2 As shown, regarding the first control module, in some embodiments, the first control module 104 may optionally be a motor controller, which can control the movement of the robotic arm 105 equipped with the probe 101. Thus, during the liquid level detection method, the first control module 104 can control the probe to move downwards from its initial position to approach the liquid in the container. During the probe's descent, a capacitive sensor detects the change in the probe's capacitance value at a preset period and sends this detection data to the second control module. During this process, the capacitive sensor continuously sends the detected data to the second control module, which continuously processes the received detection data. Because the change in the capacitance value detected by the capacitive sensor is very small and easily affected by external environmental interference, data processing is required to improve the accuracy of the liquid level detection method using a capacitive sensor, finding the data that best reflects the change in liquid level within the probe. The second control module's processing of the detection data mainly involves moving average filtering and comparison with a liquid level detection threshold, which will be described in detail below.

[0034] (i) Perform moving average filtering on the sampled data and determine whether the sampled data is in a steady-state or non-steady-state condition:

[0035] (1) Set the moving average filter coefficient n, and perform average filtering on n detection data;

[0036] (2) Calculate the average value da of the above n detection data: da=(d1+d2+…+dn) / n;

[0037] (3) Calculate the difference dc between the detection data d1, d2...dn and the average value da within the filter segment respectively;

[0038] (4) Set a steady-state judgment threshold dx and compare dx with dc to determine whether the data in this filtering segment is in a steady state.

[0039] (ii) Calculate the difference between the two steady-state mean values ​​and compare it with the liquid level detection threshold to determine whether a liquid level detection event has occurred:

[0040] • Current steady-state mean: da1

[0041] • Previous steady-state mean: da0

[0042] Steady-state mean change: E = da0 - da1

[0043] • Liquid level detection threshold TTH: The change in steady-state mean value E is compared with TTH to determine whether a liquid level detection event has occurred.

[0044] (iii) When the second control module determines that the probe has come into contact with the liquid surface, the second control module sends an interrupt signal to the first control module. After receiving the interrupt signal, the first control module controls the probe to stop moving.

[0045] Figure 3 This is a schematic diagram illustrating the principle of liquid level detection threshold determination in an embodiment of this application. Figure 3 As shown, the circles represent the detection data obtained by the second control module during the probe descent process. da0 is the mean value of the previous filtering segment, da1 is the mean value of the current filtering segment, and the difference between the two is E. E is compared with TTH to determine whether the probe has contacted the liquid surface.

[0046] By processing the detection data through the second control module, more accurate data can be obtained as the final value for comparison with the liquid level detection threshold. This eliminates the capacitance value changes caused by variations in the probe's capacitance due to changes in the external environment. Furthermore, the entire data processing process is not overly complex, facilitating rapid processing and judgment by the second control module. The hardware requirements for the second control module are also not too demanding, making it a promising candidate for widespread application.

[0047] In some embodiments of this application, optionally, the liquid level detection method further includes: before the probe reaches the container opening, a first control module controls the probe to accelerate; after the probe enters the container opening, the first control module controls the probe to decelerate until the speed decreases to a preset value, then the first control module controls the probe to move at a constant speed until an interruption position, after which the speed gradually decreases to zero, wherein the interruption position is the position of the probe when the first control module receives an interruption signal. In this way, by controlling the speed of the probe during its descent, the entire liquid level detection time can be significantly shortened, improving the detection efficiency of the liquid level detection device.

[0048] Furthermore, Figure 4 This invention illustrates a schematic diagram of the velocity change during the movement of the probe in an embodiment of this application. Figure 2 and Figure 4 As shown, the probe's movement process is as follows:

[0049] (1) The probe moves downward from the initial position and reaches the liquid surface after moving a distance of L1.

[0050] (2) Upon reaching the liquid surface, the second control module detects changes in the probe capacitance and performs logical judgments, ultimately issuing an interrupt signal. Upon receiving the interrupt signal, the first control module controls the probe to begin decelerating. During this time, the motor travels a distance L2 downwards.

[0051] (3) After the probe decelerates and moves a distance of L3, its speed drops to 0 and it reaches the stop position, coming to a complete stop.

[0052] More specifically, the probe accelerates before reaching the nozzle until its speed becomes V1, and then maintains this speed until it reaches the nozzle. Upon arrival, the probe decelerates at a constant speed until its speed decreases to V2. It continues at a constant speed until it reaches the liquid surface. After contact with the liquid surface, the second control module needs time for data processing, logical judgment, and sending an interrupt signal to the first control module. Therefore, the probe continues at a constant speed of V2 until the first control module receives the interrupt signal. When the first control module receives the interrupt signal, the probe is at the interrupted position. The first control module then controls the probe to decelerate at a constant speed until its speed reaches zero. Throughout the liquid level detection process, the probe uses variable speed motion. Since the distance from the initial position to the nozzle is constant, this distance in the L1 stroke can be covered with a higher speed V1, then reduced to a lower speed V2 upon reaching the nozzle. In the L3 stroke, the initial speed is V2, and the deceleration a3 is set to the maximum to minimize the L3 stroke.

[0053] For the L1 stroke, the larger V1 is, the shorter the overall running time. For the L2 stroke, the shorter T2 is, the shorter the L2 stroke at the same running speed. For the L3 stroke, the smaller the initial speed V3 and the larger the deceleration a3 is, the shorter the L3 stroke to complete the final deceleration. Therefore, according to the control scheme of the probe movement process described above, the liquid level detection method proposed in this application has a relatively short detection time and a relatively small probe descent distance. Specifically, the overall running time T from the initial movement to the stop position is less than 500ms, and the liquid level detection distance L2+L3 is less than 3mm. It can be seen that the liquid level detection method proposed in this application has a short detection time, and because the probe insertion length is only 3mm, it can also avoid the problem of probe-carried contamination, further improving the response speed, accuracy, safety, and stability of liquid level detection.

[0054] Furthermore, regarding the data processing of the detection data by the second control module, in some embodiments of this application, the second control module compares the change between the current steady-state mean and the previous steady-state mean with a preset liquid level detection threshold to determine whether the probe is in contact with the liquid surface. This includes: if the difference between the current steady-state mean and the previous steady-state mean is greater than the liquid level detection threshold, then it is determined that the probe is in contact with the liquid surface; if the difference between the current steady-state mean and the previous steady-state mean is less than the liquid level detection threshold, then it is determined that the probe is not in contact with the liquid surface. Combining the parameters described above, it can be seen that when the change E of the steady-state mean is greater than TTH, a liquid level detection event occurs, and the working state is in the liquid level detection triggered state.

[0055] In some embodiments of this application, optionally, the determination of whether the detected data in each filtering segment is steady-state data includes: if the difference between all detected data in the filtering segment and the corresponding average value is less than the steady-state threshold, then the data in the filtering segment is determined to be steady-state data; and / or, if no more than M detected data in the filtering segment have a difference between the corresponding average value and the steady-state threshold greater than the steady-state threshold, then the data in the filtering segment is determined to be steady-state data. Combining the parameters described above, it can be seen that when the difference between the sampled data values ​​d1, d2…dn in all filtering segments and the average value da is less than dx, this segment of data is determined to be steady-state. If a steady-state judgment exemption coefficient M is set: allowing a maximum of M sampled data to have a difference between the average value and dx greater than dx, this segment of data is still determined to be steady-state.

[0056] Similarly, the steady-state judgment of the data detected by the second control module can also be based on a standard for judging non-steady-state data. A non-steady-state judgment threshold dx' is set. When the difference between the sampled values ​​d1, d2…dn in all filtering segments and the average value da is greater than dx', this segment of data is judged to be non-steady-state. A non-steady-state judgment exemption coefficient M' is set: allowing at least M sampled data points whose difference from the average value is greater than dx', this segment of data is still judged to be non-steady-state. If the second control module judges the data as non-steady-state, it discards it and continues the judgment process until steady-state data appears. Then, the mean of the current steady-state data is subtracted from the mean of the previous steady-state data to obtain the change in the steady-state mean. This change is then compared with the liquid level detection threshold to determine whether the probe is in contact with the liquid surface.

[0057] In some embodiments of this application, optionally, the liquid level detection method further includes: pre-configuring parameters in the second control module, the parameters including at least one of the following: a moving average filter coefficient, a steady-state threshold, an exemption coefficient M, and a liquid level detection threshold, wherein the configured parameter values ​​are values ​​determined after multiple trials. The selection of these parameters requires multiple trials.

[0058] Data processing in liquid level detection methods Figure 5 A flowchart illustrating the data processing procedure of an embodiment of this application is shown, as follows: Figure 5 As shown, after the liquid level detection device is powered on and initialized, an external interrupt is enabled. Then, data acquisition is started. The second control module performs a moving average filter on the most recent n data points to determine if the current state is steady. If not, it returns to continue performing a moving average filter on the next n data points. If so, it proceeds to the next step, subtracting the current steady-state mean from the previous steady-state mean to obtain the difference. This difference is then compared with the liquid level detection threshold. If it is greater than the preset threshold, an interrupt signal is issued, and the process returns to perform a moving average filter on the latest n data points, and so on. If it is less than the liquid level detection threshold, the process returns to perform a moving average filter on the latest n data points and continues processing.

[0059] Regarding the test results, Figure 6 A schematic diagram illustrating test results obtained using the liquid level detection method according to an embodiment of this application is shown, such as... Figure 6As shown in the figure, the horizontal axis represents the sampling sequence number, and the vertical axis represents the sampled value, which is the detection data detected by the capacitive sensor. The experimental data shown in the figure indicates that from sampling sequence number 1 to approximately 433, the steady-state data remained relatively stable, representing the portion shown as "Steady-state 1 - Liquid surface detected." Subsequently, the sampled values ​​experienced significant changes, as seen in the circled area ("This part is affected by the structure of the sample tube or time tube"), where the sampled values ​​changed considerably. This demonstrates that changes in the external environment of the probe, such as the container opening, can also cause drastic changes in the sampled values. Therefore, if a capacitive sensor is to be used as a liquid level detection method, a certain liquid level detection threshold must be set. The difference between the initial and subsequent values ​​should be compared with the detection threshold to eliminate drastic changes in sampled values ​​caused by the external environment, thus improving the accuracy of the detection results. Excluding the influence of the circled area, a significant drop occurs between steady-state 1 and steady-state 2 due to the probe contacting the liquid surface. Using this drop as the final value compared with the liquid level detection threshold allows for accurate determination of whether the probe has contacted the liquid surface. According to the test results shown in the figure, the liquid level detection method of this application embodiment can not only eliminate the influence of the external environment on the sampling data and improve the accuracy of the test, but also shorten the detection time and improve the response speed of liquid level detection.

[0060] On the other hand, this application also proposes a capacitive liquid level detection device, including: a probe, a capacitive sensor, a first control module and a second control module. The capacitive sensor is electrically connected to the probe and is used to monitor the liquid level change of the probe, the liquid filled in the probe and the liquid contacted by the probe, and convert the liquid level change into a capacitance change and send it to the second control module so that the first control module and the second control module execute the liquid level detection method as described above.

[0061] In some embodiments of this application, optionally, the capacitive sensor is an FDC2112 chip, and the liquid level detection device further includes an oscillation circuit. By adjusting the value of the inductance or capacitance of the oscillation circuit, and adjusting the value of the switching time of the internal register of the FDC2112 chip and the value of the reference frequency division coefficient, the sampling rate can meet the requirements of measurement accuracy.

[0062] In some embodiments of this application, optionally, the capacitive sensor is an FDC2112 chip, which uses an external clock as a reference clock. The liquid level detection device includes a P1 port, which is connected to the probe housing and the grounding electrode on the probe assembly. The interfaces I2C1_SDA, I2C1_SCL, INTB, and SD of the FDC2112 chip are connected to the second control module in the liquid level detection device. The I2C1_SDA and I2C1_SCL interfaces are used for configuring the FDC2112 chip and transmitting measurement data; the SD interface is used to set a power-off mode to save current; and the interrupt pin INTB is used to notify the second control module of the completion of a data conversion. Data transmission between the first and second control modules is achieved through the interrupt pin INTB, resulting in high data transmission efficiency. Furthermore, the first control module can configure the aforementioned parameters (n, dx, m, TTH) through the IIC2 interface on the second control module on the liquid level detection board. This is very important for IVD diagnostic equipment. Without changing the original equipment structure, only a capacitive sensor and a second control module need to be added to complete the liquid level detection function. Furthermore, the connection between the first and second control modules is simple, with only two ports, IIC2 and IIC_IRQ, connected. The processing burden of the first control module is not increased, and it does not affect the operation of the entire IVD testing equipment.

[0063] In some embodiments of this application, optionally, the capacitive sensor is the TI (Texas Instruments) FDC2112 chip, and the second control module is the STM32F103CBT6 MCU chip with an I2C communication interface. The FDC2112 employs an innovative narrowband-based architecture, which can highly suppress noise and interference while providing high resolution at high speeds, with an output rate up to 13.3 ksps and a resolution up to 12 bits, enabling the measurement of fast-moving targets. An optimal combination of sampling rate and measurement accuracy can be achieved by adjusting the values ​​of the inductor or capacitor on the second control module, as well as the switching time of the FDC2112's internal registers and the value of the reference frequency division coefficient.

[0064] Figure 7 The schematic diagram of the FDC2112 liquid level detection principle is shown, as follows: Figure 7As shown, P1 is connected to the housing of the aspiration probe and the grounding electrode on the probe assembly. I2C1_SDA, I2C1_SCL, INTB, and SD are connected to the MCU on the liquid level detection board. The I2C interface is used for configuring the FDC2112 chip and transmitting measurement data. SD is used to set the power-off mode to save current. The interrupt pin INTB is used to notify the MCU on the liquid level detection board of the completion of a data conversion. The data filtering and detection event judgment functions proposed in this embodiment are implemented inside the second control module. The difference between the steady-state average values ​​before and after the probe enters the liquid level is compared with a threshold to determine whether the probe has contacted the liquid surface. Then, the liquid level detection result is transmitted to the first control module through another I2C interface of the second control module. The FDC2112 has strong anti-interference capabilities and high reliability. The data transmission efficiency between the first and second control modules is high, and the response speed is fast, improving the accuracy and detection speed of liquid level detection.

[0065] This application also proposes an in vitro diagnostic (IVD) device, including the aforementioned liquid level detection device, wherein the probe is a probe in the in vitro diagnostic (IVD) device, and the first control module is a motor controller in the in vitro diagnostic (IVD) device.

[0066] This application also provides a computer-readable storage medium storing a computer program or instructions that, when executed, implement the steps of the method designed in the above embodiments.

[0067] This application also provides a computer program product, including a computer program or instructions, which, when executed, implement the steps of the method designed in the above embodiments. For example, the computer program product may be a software installation package.

[0068] Those skilled in the art should understand that the functions of the methods, steps, or related modules / units described in the embodiments of this application can be implemented, in whole or in part, by software, hardware, firmware, or any combination thereof. When implemented in software, it can be implemented, in whole or in part, as a computer program product, or by a processor executing computer program instructions. The computer program product includes at least one computer program instruction, which can be composed of corresponding software modules. These software modules can be stored in RAM, flash memory, ROM, EPROM, EEPROM, registers, hard disk, portable hard disk, read-only optical disc (CD-ROM), or any other form of storage medium well known in the art. The computer program instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, the computer program instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired or wireless means. The computer-readable storage medium can be any available medium accessible to a computer or a data storage device such as a server or data center that integrates one or more available media. The available media can be magnetic media (e.g., floppy disks, hard disks, magnetic tapes), optical media, or semiconductor media (e.g., SSDs).

[0069] Regarding the various devices / products described in the above embodiments, the modules / units included can be software modules / units, hardware modules / units, or a combination of both. For example, for devices / products applied to or integrated into a chip, all of its modules / units can be implemented using hardware methods such as circuits, or at least some modules / units can be implemented using software programs running on a processor integrated within the chip, while the remaining modules / units can be implemented using hardware methods such as circuits. Similarly, for devices / products applied to or integrated into a terminal, all of its modules / units can be implemented using hardware methods such as circuits, or at least some modules / units can be implemented using software programs running on a processor integrated within the terminal, while the remaining modules / units can be implemented using hardware methods such as circuits.

[0070] The above description is merely a specific implementation of this application. Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems, modules, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here. It should be understood that the protection scope of this application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this application, and these modifications or substitutions should all be covered within the protection scope of this application.

[0071] The above embodiments are for illustrative purposes only and are not intended to limit the invention. Those skilled in the art can make various changes and modifications without departing from the scope of the invention. Therefore, all equivalent technical solutions should also fall within the scope of the invention.

Claims

1. A liquid level detection method, characterized in that, The method is based on a capacitive liquid level detection device, which includes a probe, a capacitive sensor, a first control module, and a second control module. The capacitive sensor can convert the liquid level changes of the probe, the liquid filling the probe, and the liquid contacted by the probe into changes in equivalent capacitance. The liquid level detection method includes: The first control module controls the probe to move down from its initial position to approach the liquid in the container; During the probe's descent, the capacitance sensor detects the change in the probe's capacitance value at preset intervals and sends the detection data to the second control module. The second control module performs moving average filtering on the acquired multiple detection data to obtain the average value of the detection data within multiple filtering segments. It then obtains the difference between each average value and each detection data within the corresponding filtering segment, and compares each of the obtained differences with a preset steady-state threshold to determine whether the detection data within each filtering segment is steady-state data. If it is steady-state data, the average value of the corresponding filtering segment is taken as the steady-state mean; otherwise, it is discarded. The second control module compares the change between the current steady-state mean and the previous steady-state mean with a preset liquid level detection threshold to determine whether the probe has contacted the liquid surface; wherein, when it is determined that the probe has contacted the liquid surface, the second control module sends an interrupt signal to the first control module, so that the first control module controls the probe to stop moving; The step of setting a steady-state judgment exemption coefficient M, and determining whether the detection data in each filter segment is steady-state data, includes: If the difference between all detected data and their corresponding average values ​​within the filter segment is less than the steady-state threshold, then the data within the filter segment is determined to be steady-state data. If no more than M detection data points within the filter segment have a difference greater than the steady-state threshold between them and their corresponding average values, then the data within the filter segment is determined to be steady-state data.

2. The method according to claim 1, characterized in that, The method further includes: Before the probe reaches the opening of the container, the first control module controls the probe to accelerate. After the probe enters the container opening, the first control module controls the probe to decelerate until the speed decreases to a preset value. Then, the first control module controls the probe to move at a constant speed until the interruption position, after which the speed gradually decreases to zero. The interruption position is the position of the probe when the first control module receives the interruption signal.

3. The method according to claim 1, characterized in that, The second control module compares the change between the current steady-state mean and the previous steady-state mean with a preset liquid level detection threshold to determine whether the probe is in contact with the liquid surface, including: If the difference between the current steady-state mean and the previous steady-state mean is greater than the liquid level detection threshold, then it is determined that the probe is in contact with the liquid surface; If the difference between the current steady-state mean and the previous steady-state mean is less than the liquid level detection threshold, then it is determined that the probe has not contacted the liquid surface.

4. The method according to claim 1, characterized in that, The method further includes: The parameters in the second control module are pre-configured, including at least one of the following: moving average filter coefficient, steady-state threshold, exemption coefficient M, and liquid level detection threshold, wherein the configured parameter values ​​are determined after multiple tests.

5. A capacitive liquid level detection device, characterized in that, include: The system comprises a probe, a capacitive sensor, a first control module, and a second control module. The capacitive sensor is electrically connected to the probe and is used to monitor the liquid level change of the probe, the liquid filling the probe, and the liquid contacted by the probe. The capacitive sensor converts the liquid level change into a capacitance change and sends it to the second control module, so that the first control module and the second control module execute the method as described in any one of claims 1-4.

6. The capacitive liquid level detection device according to claim 5, characterized in that, The capacitive sensor is an FDC2112 chip. The liquid level detection device also includes an oscillation circuit. By adjusting the inductance or capacitance of the oscillation circuit, and adjusting the switching time of the internal register of the FDC2112 chip and the value of the reference frequency division coefficient, the sampling rate can meet the measurement accuracy requirements.

7. The capacitive liquid level detection device according to claim 5, characterized in that, The capacitive sensor is an FDC2112 chip, and the FDC2112 chip uses an external clock as a reference clock. The liquid level detection device includes a P1 port, which is connected to the probe housing and the grounding body on the probe assembly. The FDC2112 chip's interfaces I2C1_SDA, I2C1_SCL, INTB, and SD are connected to the second control module in the liquid level detection device. The I2C1_SDA and I2C1_SCL interfaces are used for configuring the FDC2112 chip and transmitting measurement data; the SD interface is used to set the power-off mode to save current; and the interrupt pin INTB is used to notify the second control module of the completion of a data conversion.

8. An in vitro diagnostic (IVD) device, characterized in that, The device includes a liquid level detection device as described in any one of claims 5-7, wherein the probe is a probe in an in vitro diagnostic (IVD) device, and the first control module is a motor controller in the IVD device.

9. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer program instructions that, when executed by a processor, implement the method as described in any one of claims 1-4.

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