An electrochemical sensor for measuring the electrical conductivity and dielectric constant of a liquid

Abstract

This application relates to the field of on-line liquid monitoring, and provides an electrochemical sensor for measuring the conductivity and dielectric constant of a liquid, including: a probe, which includes a first electrode sheet, a second electrode sheet, and a third electrode sheet arranged successively; a measurement circuit, which includes an RC circuit, an amplification circuit, a comparison circuit, and a NOT gate circuit, and the NOT gate circuit is used to obtain a fourth voltage u 4, wherein the high-level duration in the fourth voltage u 4 is the first time t 1, and the low-level duration in the fourth voltage u 4 is the second time t 2, and the first time t 1 and the second time t 2 are used to determine the conductivity and the dielectric constant. This application determines the dielectric properties through precise time measurement, integrates measurement technology and high time / bandwidth, and has very high precision and repeatability. The accuracy of the conductivity can reach picoseconds per meter (pS / m), and the accuracy of the dielectric constant can reach 0.0001.

Description

Technical Field

[0001] This application relates to the field of on-line liquid monitoring. Specifically, it relates to an electrochemical sensor for measuring the conductivity and dielectric constant of a liquid. Background Art

[0002] The rapid analysis and determination of the quality and its change characteristics of liquids such as oil (e.g., lubricating oil), ethanol, etc. are the premise and guarantee for ensuring the safe and efficient operation of industrial equipment lubricated with liquids such as oil and ethanol. Different from chemical analysis methods that obtain information on the composition and structure of substances based on chemical reactions, at present, physical analysis methods are usually used to analyze the physical and chemical characteristics of liquids, such as instrumental analysis techniques like spectral analysis, spectroscopic analysis, and organic mass spectrometry. For example, in the field of lubricating oil analysis and testing, the physical and chemical properties (force, sound, heat, electricity, light, etc.) of lubricating oil are the focus of various current physical analysis techniques. For example, spectroscopic analysis techniques (infrared spectroscopy, near-infrared spectroscopy, Raman spectroscopy, etc.) make full use of the optical physical properties of lubricating oil.

[0003] Dielectric properties are one of the important physical properties of liquids used for industrial lubrication such as lubricating oil and ethanol. Its dielectric properties are mainly characterized by dielectric constant and conductivity. The dielectric constant / conductivity analysis method is a feasible analysis method for evaluating the oxidation decay process of liquids. The measured values of dielectric property parameters (dielectric constant and conductivity) of liquids such as lubricating oil during the deterioration process have a good linear relationship with quality indicators such as acid-base value.

[0004] However, at present, the main methods for measuring the dielectric properties of electrochemical sensors are capacitance method, impedance analysis method, resonance method, etc. The accuracy of the dielectric constant and conductivity measured by these methods is relatively low, which in turn leads to a high degree of uncertainty in the monitoring results of the on-line monitoring system. The reason is that liquids such as lubricating oil and ethanol have a very high resistance R and a very low capacitance C, which results in relatively high errors and low resolutions of measurement methods such as capacitance method, impedance analysis method, and resonance method, and the measurement accuracy cannot be achieved. Therefore, at present, there is an urgent need for an electrochemical sensor for monitoring the dielectric properties of liquids with higher measurement resolution and smaller errors. Summary of the Invention

[0005] This application provides an electrochemical sensor for measuring the conductivity and dielectric constant of a liquid. The dielectric properties are determined by precise time measurement, that is, the measurement technology and high time / bandwidth are integrated together. Finally, the measured conductivity and dielectric constant have very high precision and repeatability. Among them, the accuracy of conductivity can reach 1 picosiemens per meter (pS / m) and the sensitivity can reach 0.1 pS / m, and the accuracy of the dielectric constant can reach 0.0001 and the sensitivity can reach 1×10 -6 .

[0006] The electrochemical sensor includes: a probe, which includes a first electrode sheet, a second electrode sheet, and a third electrode sheet arranged successively, wherein the first electrode sheet and the second electrode sheet close to the sensor are connected by two electrode columns, and the third electrode sheet on the outermost side of the sensor is connected to the second electrode sheet by one electrode column; a measurement circuit, which includes an RC circuit, an amplification circuit, a comparison circuit, and a NOT gate circuit. The RC circuit is used to measure the voltage change of the liquid, and the amplification circuit is used to amplify the voltage change of the RC circuit to obtain a first voltage u 1 , and the comparison circuit is used to compare the first voltage output by the amplification circuit u 1 and 0 to obtain a third voltage u 3 , and the NOT gate circuit is used to compare the third voltage u 3 and a second voltage applied to the measurement circuit u 2 to obtain a fourth voltage u 4 , wherein the duration of the high level in the fourth voltage u 4 is a first time t 1 , and the duration of the low level in the fourth voltage u 4 is a second time t 2 , and the first time t 1 and the second time t 2 are used to determine the conductivity and the dielectric constant.

[0007] In the embodiments of the present application, the structure of three electrode sheets is preferably used as the probe of the sensor. Through the structure of three electrode sheets in the embodiments of the present application, the measurement accuracy and stability are improved, and the construction and maintenance costs of the three electrode sheet structure are relatively low, and there is no need for a complex setting and calibration process. By introducing a reference electrode, the three electrode sensor can largely eliminate the influence of the polarization effect on the measurement, thereby improving the measurement accuracy and stability. The potential of the reference electrode is stable and not affected by the change of the electrolyte composition, and can be used as a reference benchmark for the electrode, so that the electrochemical reaction is only affected by the substance to be measured. Through the structure of three electrode sheets in the present application, the sensor in the embodiments of the present application has a wider measurement range. The measurement unit of the conductivity can reach 0.1~2000000 pS / m, and the range of the relative dielectric constant (the ratio of the dielectric constant of the dielectric to the dielectric constant in vacuum) can reach 1~6.

[0008] In an embodiment of the present application, a comparison circuit and a NOT gate circuit are introduced. Instead of obtaining the dielectric properties by measuring R and C, the dielectric properties are determined by precise time measurement. That is, the measurement technology and high time / bandwidth are integrated together. Finally, the measured conductivity and permittivity have very high accuracy and repeatability.

[0009] Optionally, the electrochemical sensor may further include a housing material for protecting the internal sensitive components, which not only needs to be able to withstand external physical impacts and chemical corrosion, but also has excellent heat dissipation performance and sealing performance. Common housing materials include metals, plastics, and ceramics, etc.

[0010] Optionally, the structure of the sensor can adopt a standardized design to facilitate quick connection and interchange with other devices or systems. For example, modern sensors often integrate multiple interface types such as RS485, etc. to meet the requirements of different application scenarios. At the same time, in order to improve the reliability and speed of data transmission, the sensor in the embodiment of the present application can also adopt wireless communication technologies such as 4 / 5G, Wi-Fi, etc.

[0011] Combined with the first aspect, in a possible implementation manner of the first aspect, the liquid includes at least one of oil, methanol, and ultrapure water, and the oil includes at least one of lubricating oil, hydraulic oil, and transformer oil.

[0012] Combined with the first aspect, in a possible implementation manner of the first aspect, the third electrode plate is a reference electrode, and the first electrode plate and the second electrode plate are a working electrode and an auxiliary electrode respectively.

[0013] In an embodiment of the present application, adding a reference electrode plate is equivalent to connecting an external voltage stabilizing circuit, which can stabilize the electromotive force of the sensitive electrode. At the same time, no current passes through the reference electrode to maintain the stability of their respective voltages. In this way, even if the negative electrode is continuously polarized, it will not have any impact on the working electrode. The greatest advantage of the three-electrode design is that it provides a bias voltage for the sensor, enhancing the reaction activity of some inactive gases, making them undergo oxidation or reduction reactions. The electromotive force of the reference electrode generally does not undergo a bias catalytic reaction.

[0014] Combined with the first aspect, in a possible implementation manner of the first aspect, the first time t 1 and the second time t 2 are used to determine the conductivity and the permittivity, including:

[0015] The conductivity k is determined by the following formula:

[0016] ;

[0017] Wherein, l is the spacing between the first electrode sheet, the second electrode sheet and the third electrode sheet; A is the surface area of the electrode plate; C is a known capacitance.

[0018] Combined with the first aspect, in a possible implementation manner of the first aspect, the first time t 1 and the second time t 2 are used to determine the conductivity and the dielectric constant, including:

[0019] The dielectric constant is obtained through the following formula:

[0020] ;

[0021] Wherein, k is the conductivity, is the dielectric constant in vacuum.

[0022] In the above formula, the conductivity and the dielectric constant are not directly calculated through the resistance R and the capacitance C, but are calculated using more accurate time values. By integrating the measurement technology with high time / bandwidth, it has very high accuracy and repeatability.

[0023] Combined with the first aspect, in a possible implementation manner of the first aspect, the electrochemical sensor further includes a self-cleaning module. After the electrochemical sensor measures, the self-cleaning module is used to release acetone or ethylene glycol to clean the probe of the sensor.

[0024] The sensor in the embodiment of the present application can be used for the measurement of various liquids. Therefore, it is possible that the sensor measures one liquid and then is used to measure another liquid. Through the self-cleaning module, the probe of the sensor is made more sensitive during the next measurement.

[0025] Combined with the first aspect, in a possible implementation manner of the first aspect, the electrochemical sensor is also used to measure the temperature and pressure of the liquid.

[0026] By integrating multiple measurement functions, it helps to reduce the number of sensors in the device, and reduce costs and complexity.

[0027] Combined with the first aspect, in a possible implementation manner of the first aspect, the electrochemical sensor uses low-power materials and technologies, and realizes an intelligent wake-up mechanism (that is, the sensor is only activated when needed).

[0028] In a second aspect, a liquid on-line monitoring system is provided. The liquid on-line monitoring system includes a sensor module, and the sensor module includes the electrochemical sensor as described in any one of the implementation manners in the first aspect.

[0029] Optionally, the liquid on-line monitoring system may further include multiple modules such as a data acquisition device, a data processing and analysis module, a communication module, and an early warning module. Description of the Drawings

[0030] Figure 1 is a schematic diagram of an oil liquid on-line monitoring system provided by an embodiment of the present application.

[0031] Figure 2 is a schematic diagram of an electrochemical sensor for measuring the conductivity and dielectric constant of a liquid provided by an embodiment of the present application.

[0032] Figure 3 is a schematic diagram of a measurement circuit provided by an embodiment of the present application.

[0033] Figure 4 is a schematic diagram of a measurement waveform of a measurement circuit provided by an embodiment of the present application. Detailed Description of the Embodiments

[0034] The embodiments of the present application will be described in detail below. Examples of the embodiments of the present application are shown in the drawings. In the drawings, the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the drawings are exemplary and are only used to explain the present application and should not be construed as a limitation of the present application.

[0035] Unless otherwise defined, the technical terms or scientific terms used herein shall have the ordinary meanings understood by those of ordinary skill in the technical field to which the present application belongs. In the description of the present application, it should be understood that the terms "center", "longitudinal", "transverse", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present application.

[0036] References to "one embodiment" or "some embodiments" in this specification mean that a particular feature, structure, or characteristic described in connection with the embodiment is included in one or more embodiments of the present application. Thus, statements such as "in one embodiment", "in some embodiments", "in other some embodiments", "in still other embodiments", etc. that appear in different places in this specification do not necessarily all refer to the same embodiment, but mean "one or more but not all embodiments", unless otherwise specifically emphasized. The terms "comprising", "including", "having" and their variants all mean "including but not limited to", unless otherwise specifically emphasized.

[0037] For ease of understanding, the on-line monitoring system to which the electrochemical sensor of the embodiments of the present application is applied is first introduced. Among them, the on-line monitoring system may be an on-line monitoring system for monitoring oil (such as lubricating oil), ethanol, methanol, or ultrapure water, etc. Hereinafter, the on-line monitoring system of the embodiments of the present application will be introduced by taking the on-line monitoring system of oil as an example.

[0038] Oil monitoring technology is an important technical means to realize the monitoring of equipment lubrication status and wear fault diagnosis. Its principle is mainly to obtain information on the lubrication and wear status of the equipment friction pair by analyzing the physical and chemical performance indexes of the lubricating oil in use in the equipment, the moisture in the oil, the wear metal particles, and the pollution products, so as to diagnose the lubrication status and wear fault of the equipment. Figure 1 A schematic diagram of an oil on-line monitoring system 100 provided by an embodiment of the present application is shown.

[0039] As Figure 1 shown, the on-line monitoring system 100 of oil is a comprehensive system integrating multiple modules such as sensors, data acquisition devices, data processing and analysis modules, communication modules, and warning modules. The on-line monitoring system 100 of oil is mainly used to monitor and analyze the conditions of liquids such as lubricating oil and hydraulic oil in an industrial equipment during oil inlet or oil return in a fuel tank, so as to ensure the normal operation of the equipment and reduce the maintenance cost. Exemplarily, the modules mainly included in the on-line monitoring system 100 of oil are:

[0040] 1. A sensor module, which is used to measure key parameters of the oil, such as temperature, conductivity, dielectric constant, moisture content, water activity, moisture, acid value, viscosity, density, particle size. For example, data of the oil can be collected and converted into an electrical signal by means of contacting the oil or transmitting through the oil. These sensors usually include a viscosity sensor, a pollution particle sensor, a dielectric property sensor, etc.

[0041] 2. Data acquisition module, which is used to receive and process the data signals transmitted by sensors. It can sample, convert and store data for subsequent analysis and management. Data acquisition can be carried out by wired or wireless means to ensure real-time performance.

[0042] 3. Data processing and analysis software module, which is used to perform real-time analysis, trend analysis, fault diagnosis and prediction on the acquired data, and generate reports and alerts. It can provide an intuitive graphical interface to facilitate users to view the change trends and abnormal conditions of the oil fluid state. In addition, it can also predict the fault trends of equipment through data models and analysis algorithms, and take measures in advance to prevent faults from occurring.

[0043] 4. Communication and remote monitoring module, which is used to realize the communication between the system and remote terminals or cloud platforms, as well as the remote transmission and monitoring of data. Users can remotely view the state of the oil fluid, analysis reports and receive alert notifications through devices such as smartphones, tablets or computers. At the same time, they can also remotely control the setting and adjustment of equipment parameters.

[0044] 5. Early warning and notification module, which is used to trigger the alarm and notification mechanism according to the set thresholds or conditions. When the oil fluid parameters exceed the preset range, the system can automatically issue an alarm and notify relevant personnel so that corresponding measures can be taken in a timely manner.

[0045] In summary, through the collaborative work of these modules, the oil fluid on-line monitoring system can realize functions such as real-time monitoring of the oil fluid state, data analysis and early warning notification, thereby improving the reliability and operation efficiency of equipment and reducing maintenance costs.

[0046] It should be noted that Figure 1 only taking the on-line monitoring system 100 of the oil fluid as an example does not limit the protection scope of this application. Those skilled in the art can easily apply the Figure 1 shown system architecture to the on-line monitoring systems of liquids such as methanol and ultrapure water.

[0047] As can be seen from the above, the sensor module of the on-line monitoring system can be used to measure multiple key parameters of liquids, such as the physical and chemical properties of liquids, etc. Among them, the dielectric property is one of the important physical properties of liquids such as the oil fluid and methanol introduced above, and its dielectric property is mainly characterized by the dielectric constant and conductivity. For example, there are two aspects to the related application research using the dielectric property of lubricating oil: one aspect is the analysis and testing of in-use lubricating oil, using the changes in the dielectric constant or conductivity of in-use lubricating oil to detect or monitor the quality changes of lubricating oil, and then monitor the operation state of equipment; the second aspect is to correlate the quality indicators of lubricating oil with the dielectric constant of lubricating oil in order to achieve the purpose of measuring its related quality indicators using the dielectric constant of lubricating oil.

[0048] In addition, the dielectric constant / conductivity analysis method is a feasible method for evaluating the oxidation decay process of liquids. There is a good linear relationship between the measured values of dielectric performance parameters (dielectric constant and conductivity) of liquids such as lubricating oil during the deterioration process and quality indicators such as acid-base value.

[0049] Generally speaking, the higher the cleanliness of the lubricating oil, the lower its dielectric constant and the higher its resistivity. This is the basis for monitoring the cleanliness of lubricating oil using its dielectric constant and resistivity. After the lubricating oil is contaminated and deteriorated, some hydrocarbon molecules in the oil are oxidized into peroxides, acids and other groups, causing molecular polarization. The deeper the oxidation degree of the lubricating oil, the relatively higher the content of polar substances in it, indicating the stronger the polarity of the oil. Therefore, the dielectric constant of the oil will increase accordingly.

[0050] Therefore, in the on-line monitoring technologies of liquids such as oil, methanol, and ultrapure water, the on-line monitoring of the dielectric properties of liquids is very important. That is to say, the sensor for monitoring dielectric properties is an important part of the sensor module of the on-line monitoring system.

[0051] At present, sensors for monitoring the dielectric properties of liquids usually measure dielectric properties through the following methods: capacitance method, impedance analysis method, resonance method, etc. For example, the capacitance method is based on the basic principle of a capacitor and calculates the dielectric constant (ε) of a material by measuring the capacitance value when the sample is used as the dielectric between the capacitor plates. Another example is that the impedance analysis method is a method for evaluating the dielectric properties by measuring the impedance characteristics of a sample in an alternating electric field. This method uses an impedance analyzer to measure the impedance and phase angle of the sample in a relatively wide frequency range, so as to obtain the complex dielectric constant (ε* = ε′ - jε″, where ε′ is the real part of the dielectric constant and ε″ is the imaginary part of the dielectric constant, related to dielectric loss). Another example is that the resonance method is a method for measuring the dielectric constant by using the relationship between the resonance frequency of the circuit formed by the sample and the circuit and the dielectric constant of the sample. This method usually uses a microwave resonance cavity or an LC resonance circuit, places the sample in the resonance circuit, and calculates the dielectric constant of the sample by measuring the change in the resonance frequency.

[0052] However, since liquids such as lubricating oil and methanol have very high resistance R and very low capacitance C, and the above-mentioned several methods for measuring dielectric properties all require the use of resistance values or capacitance values. The very high resistance R and very low capacitance C will affect the resistance value and capacitance value during measurement, reduce the resolution of the measurement result, increase the error of the measurement result, and ultimately affect the measurement accuracy of the dielectric constant and conductivity, resulting in a high degree of uncertainty in the monitoring results of the on-line monitoring system.

[0053] In other words, at the current stage, the measurement resolution of sensors for measuring dielectric properties is low and the error is large, resulting in inaccurate measurement results of the sensors. To solve the above problems, the embodiments of the present application disclose an electrochemical sensor for measuring the conductivity and dielectric constant of a liquid. The measurement accuracy of this electrochemical sensor is higher, where the accuracy of conductivity can reach 1 picosiemens per meter (pS / m) and the sensitivity can reach 0.1 pS / m, and the accuracy of the dielectric constant can reach 0.0001 and the sensitivity can reach 1×10 -6 .

[0054] The following introduces the electrochemical sensor provided by the embodiments of the present application with reference to the drawings.

[0055] Figure 2 shows the external schematic diagram of the electrochemical sensor 200 provided by the embodiments of the present application and the structural schematic diagram of the probe. As Figure 2 shown in (a) therein, the electrochemical sensor 200 includes a housing part and a probe connected to the housing. The housing part of the sensor is used to protect the internal sensitive components, and it not only needs to be able to withstand external physical impacts and chemical corrosions, but also needs to have excellent heat dissipation performance and sealing performance. Common housing materials include stainless steel, engineering plastics, etc.

[0056] The interface and connector of the sensor are the key parts for data transmission and control. In the embodiments of the present application, a standardized design can be adopted to facilitate quick connection and interchange with other devices or systems. For example, modern sensors often integrate multiple interface types such as RS485, etc., to meet the requirements of different application scenarios. At the same time, in order to improve the reliability and speed of data transmission, the sensors in the embodiments of the present application can also adopt wireless communication technologies such as 4 / 5G, Wi-Fi, etc.

[0057] Figure 2 The probe shown is the sensitive component of the sensor, which is the part in the sensor that directly responds to the measurement and converts the physical quantity signal of the liquid to be measured into an electrical signal (such as voltage, current, resistance, etc.). In the embodiments of the present application, a three-electrode structure is preferably used as the probe of the sensor. As Figure 2 shown in (b) therein, the three-electrode probe includes three arranged electrode plates. Among them, the two electrode plates closer to the inside of the sensor housing are connected by two electrode columns, and the outermost electrode plate is only connected to the middle electrode plate by one electrode column. Among them, the outermost electrode plate (i.e., Figure 2 the uppermost electrode plate in (b) therein) functions as a reference electrode (which can also be called a reference electrode, a reference electrode, a datum electrode, etc.), and the other two electrode plates are the working electrode and the auxiliary electrode respectively.

[0058] In current two - electrode sensors, the measurement is restricted by the negative - electrode polarization effect. Therefore, in the embodiments of this application, adding a reference - electrode piece is equivalent to connecting an external voltage - stabilizing circuit, which can stabilize the electromotive force of the sensitive electrode. Meanwhile, no current passes through the reference electrode, maintaining the stability of their respective voltages. Thus, even if the negative electrode is continuously polarized, it will have no impact on the working electrode. The greatest advantage of the three - electrode design is that it provides a bias voltage for the sensor, enhancing the reactivity of some inactive gases and enabling them to undergo oxidation or reduction reactions. Generally, the reference - electrode electromotive force does not undergo a bias - catalysis reaction.

[0059] It should be noted that those skilled in the art should understand that the selection of the three - electrode piece as the sensor - electrode structure in the embodiments of this application is not simply a modification of the number of electrode pieces of the existing two - electrode piece and four - electrode piece, but takes into account the specific scenario of measuring the liquid conductivity (i.e., dielectric constant) in this application. In other words, the selection of the number of electrode pieces as three - electrode pieces in the embodiments of this application is not arbitrary.

[0060] First, as mentioned above, in the sensor with a three - electrode - piece probe in the embodiments of this application, the introduction of the reference electrode can stabilize the potential of the working electrode, thus effectively reducing the influence of the polarization effect on the measurement. In the measurement of liquids such as oil products and methanol, the polarization effect may cause the measurement signal to be distorted, thereby affecting the measurement accuracy. The three - electrode design ensures the accuracy and stability of the measurement signal by separating the polarization current and the measurement current.

[0061] Second, the conductivity of liquids such as oil products and methanol may vary due to various factors such as temperature and water content. The three - electrode sensor can compensate for the conductivity change online, eliminating the influence of this change on the measurement accuracy. This is particularly important for the monitoring of liquids such as oil products and methanol because the change in the liquid state is often accompanied by a change in conductivity. For example, the sensor with three - electrode pieces can extract the fluctuation information of the liquid film under the condition of a large - range change in the liquid - film conductivity and can compensate for the influence of the conductivity change on the liquid - film thickness measurement online.

[0062] Third, the measurement accuracy and stability of the probe structure with four - electrode pieces or more electrode pieces are higher. However, increasing the number of electrode pieces will undoubtedly increase the manufacturing cost of the sensor. More electrode pieces also mean more potential failure points and more complex maintenance procedures. And although the probe structure with four - electrode pieces or more electrode pieces can provide more advanced measurement capabilities in some cases, such as more precisely measuring the impedance value of the solution - phase interface, in general electrochemical - property measurements, its complexity may not always bring a significant improvement in accuracy.

[0063] In summary, the embodiments of the present application adopt a three - electrode structure to improve the measurement accuracy and stability. Moreover, the construction and maintenance costs of the three - electrode structure are relatively low, and no complex setup and calibration processes are required. By introducing a reference electrode, the three - electrode sensor can largely eliminate the influence of polarization effects on measurement, thereby improving the measurement accuracy and stability. The potential of the reference electrode is stable and not affected by changes in the electrolyte composition, which can serve as a reference benchmark for the electrode, enabling the electrochemical reaction to be affected only by the substance to be measured. Through the three - electrode structure of the present application, the sensor of the embodiments of the present application has a wider measurement range. The measurement unit of conductivity can reach 0.1 - 2000000 pS / m, and the range of relative dielectric constant (the ratio of the dielectric constant of the dielectric to the dielectric constant in a vacuum) can reach 1 - 6.

[0064] Finally, as shown in (c) of Figure 2 , (c) of Figure 2 includes a sensor fixing base for fixing the sensor and a pipeline coupled to the sensor fixing base for conveying liquid. The electrochemical sensor shown in (a) of Figure 2 is fixed by the sensor fixing base. After the liquid in the pipeline, such as oil, methanol, etc., passes through the probe, the probe of the sensor converts the physical signal of the liquid into an electrical signal.

[0065] Figure 3 shows Figure 2 the measurement circuit structure diagram in the electrochemical sensor 200 shown in

[0066] As shown in Figure 3 , this measurement circuit includes four parts: an RC circuit, an amplification circuit, a comparison circuit (or comparator), and a NOT - gate circuit.

[0067] Among them, the RC circuit is used to measure the voltage change of the liquid, that is, to measure the change of the voltage signal converted by the probe. The amplification circuit is used to amplify the voltage signal converted by the probe. The RC circuit and the amplification circuit are the main parts of the measurement circuit of the current - stage sensor. According to the above, since liquids such as oil and methanol have a large resistance R and a small capacitance C, when only using the RC circuit for measurement, its accuracy is relatively low. Therefore, as shown in Figure 3 , in the embodiments of the present application, a comparison circuit and a NOT - gate circuit are introduced, and the method of obtaining dielectric properties by measuring R and C is replaced with determining dielectric properties through precise time measurement. That is, the measurement technology and high time / bandwidth are integrated together, and finally the measured conductivity and dielectric constant have very high accuracy and repeatability.

[0068] First, the structure of the measurement circuit will be introduced in combination with Figure 3 . As shown inFigure 3 As shown, the first end on the left side of the RC circuit is connected to the first input terminal on the left side of the NOT gate circuit (i.e., Figure 3 the input terminal shown above), and the second end on the right side of the RC circuit is connected to the first end on the left side of the amplifier circuit. Among them, the electric potential on the left side of the RC circuit is u 2 , and thus the electric potential at the first input terminal of the NOT gate circuit is also u 2 . After being amplified by the amplifier circuit, the electric potential on the right side of the RC circuit is u 1 . The second end on the right side of the amplifier circuit is connected to the two input terminals of the comparison circuit. The comparison circuit compares the u 1 output by the amplifier circuit with the electric potential 0 and outputs the electric potential u 3 . The first output terminal of the comparison circuit (i.e., Figure 3 the output terminal shown above) is connected to the first input terminal of the NOT gate circuit and the first end of the RC circuit, and the second output terminal of the comparison circuit (i.e., Figure 3 the output terminal shown below) is connected to the second input terminal of the NOT gate circuit. The NOT gate circuit compares the u 2 at the first input terminal and the u 3 at the second input terminal to obtain the electric potential u 4 . The waveform of this electric potential u 4 can be used to calculate the conductivity and dielectric constant through precise time measurement.

[0069] Next, the measurement method and measurement process of this application based on the Figure 4 circuit shown will be introduced. Figure 3 As shown in the figure, when applying the electric potential

[0070] As Figure 4 shown, when applying the electric potential u 2 to the circuit or the left side of the RC circuit, the voltages across the resistor R and the capacitor C will change. Figure 4 As shown u 1 the change is the change in the voltages across the resistor R and the capacitor C. For example, when u 2 is -1 (high level in the reverse direction), the capacitor C discharges to 0 and then charges, that is, u 1 first drops to 0 and then rises. When u 2 is 1 (high level), the capacitor C also discharges to 0 and then charges.

[0071] The comparison circuit compares the u 1 potential value with 0 to obtain u 3 . Among them, when u 1 is greater than 0, u 3 has a value of 1; when u 1 is less than 0, u 3 has a value of -1. The NOT gate circuit compares the value of u 2 with the value of u 3 to obtain u 4 . That is, when the value of u 2 is the same as the value of u 3 , u 4 is 0, and when the value of u 2 is different from the value of u 3 , u 4 is 1. Finally, as shown in Figure 4 , u 4 includes the high-level duration t 1 and the low-level duration t 2 , and these two time values can be used to calculate the conductivity and dielectric constant of the liquid.

[0072] Exemplarily, for a uniform liquid, the relationship between the resistance R and the conductivity k is:

[0073] ;

[0074] Among them, l is the electrode plate spacing, that is, the spacing between the three electrode plates shown in Figure 2 ; A is the electrode plate surface area.

[0075] Also, since the relationship between the capacitance C and the resistance R is:

[0076] ;

[0077] Among them, is the time constant. In the embodiments of the present application, The value of t 1 can be

[0078] Therefore, the conductivity of the liquid can be obtained by the following formula:

[0079] ;

[0080] Similarly, the dielectric constant of the liquid can be obtained by the following formula:

[0081] ;

[0082] wherein, k is the conductivity, is the dielectric constant in vacuum (about 8.854×10 −12  F / m).

[0083] It should be noted that the above formula is only an example. In this application, other more accurate calculation methods can also be used to calculate the conductivity and dielectric constant through the duration of the high level t 1 and the duration of the low level t 2 accurately.

[0084] In other words, in the embodiments of this application, the electrochemical sensor does not directly calculate the conductivity and dielectric constant through the resistance R and capacitance C, but uses more accurate time values to calculate the conductivity and dielectric constant. By integrating the measurement technology with high time / bandwidth, it has very high accuracy and repeatability. The accuracy of the conductivity can reach 1 picosiemens per meter (pS / m), and the accuracy of the dielectric constant can reach 0.0001.

[0085] Optionally, in some other embodiments of this application, when measuring the liquid, there may be situations such as temperature interference. Therefore, this application can target the errors caused by the characteristics or working conditions of the sensor itself and the external environment. By finding the variation law of the errors, or measuring their magnitudes and directions, and using appropriate methods (such as electronic circuits, software algorithms, etc.) for temperature compensation or correction to improve the accuracy and stability of the sensor. For example, a differential circuit can be introduced into the Figure 3 circuit shown. The differential technology can significantly reduce the influence of temperature changes, power supply fluctuations, external interferences, etc. on the sensor accuracy, cancel the common-mode errors, and reduce the non-linear errors, thereby improving the accuracy of the sensor.

[0086] Optionally, to improve the stability of the sensor, necessary stability treatments can be performed on the sensor material, components, or the entire sensor, such as time aging, temperature aging, mechanical aging, and AC stabilization treatment of permanent magnetic materials, aging screening, etc., to improve the long-term stability of the sensor performance.

[0087] Since the sensor of the embodiment of the present application can be used for the measurement of various liquids, it is possible that the sensor measures one liquid and then is used to measure another liquid. Optionally, in the embodiment of the present application, a self-cleaning module can be introduced into the sensor. After the sensor measures the conductivity and permittivity of one liquid, the self-cleaning module releases acetone or ethylene glycol to clean the probe of the sensor, thereby making the probe of the sensor more sensitive during the next measurement.

[0088] Optionally, the electrochemical sensor in the embodiment of the present application can also be used to integrate other measurement modules, such as measurement modules for measuring temperature and pressure. By integrating multiple measurement functions, it helps to reduce the number of sensors in the device, lower costs and complexity.

[0089] Optionally, the electrochemical sensor in the present application can adopt low-power materials and technologies, and implement an intelligent wake-up mechanism (i.e., activate the sensor only when needed), which can significantly reduce the power consumption of the sensor and extend the usage time of the device.

[0090] For example, the sensor can be woken up through a task cycle. For example, the wake-up period and sleep period of each node can be preset and coexist with nodes in other working modes to assist in completing specific tasks. The advantage of task-cycle wake-up is that it can clearly know the working status of each node, which is convenient for management and optimization. In addition, through reasonable task scheduling, the power consumption of the entire system can be reduced and the service life of the device can be extended.

[0091] For another example, when the sensor detects the vibration of equipment for oil delivery or oil return in the fuel tank, it triggers the wake-up of the sensor. For example, a ball mechanism and induction electrodes can be integrated in the sensor. When the environment or device where the sensor is located vibrates, the ball mechanism moves accordingly, resulting in a change in the contact state between the ball and the induction electrode, thereby generating an electrical signal. This electrical signal is processed through amplification, filtering, etc. and used to trigger the wake-up circuit.

[0092] For another example, the sensor can automatically adjust the wake-up mode mechanism according to changes in the external environment and internal state. This mechanism dynamically adjusts the wake-up strategy and parameters of the sensor by real-time monitoring factors such as environmental changes, device status, and task requirements. Exemplarily, when only the conductivity and permittivity need to be measured, the sensor reduces the sampling rate and resolution to reduce power consumption; when more parameters need to be measured and very high accuracy requirements are needed, the sampling rate and resolution are increased to improve the monitoring accuracy.

[0093] Optionally, an intelligent algorithm can be integrated into the electrochemical sensor in this application, which can self-calibrate and self-repair to reduce the number and time of maintenance and lower the maintenance cost. For example, the sensor can automatically detect and correct errors or self-repair when a failure occurs.

[0094] Those skilled in the art can clearly understand that for the convenience and conciseness of description, the specific working processes of the systems, devices, and units described above can refer to the corresponding processes in the foregoing method embodiments and will not be elaborated herein.

[0095] In the several embodiments provided in this application, it should be understood that the disclosed systems, devices, and methods can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For example, the division of the units is only a logical function division, and there can be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the displayed or discussed couplings or direct couplings or communication connections to each other can be through some interfaces, and the indirect couplings or communication connections of the devices or units can be in electrical, mechanical, or other forms.

[0096] The units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they can be located in one place or distributed to multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0097] In addition, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically alone, or two or more units can be integrated into one unit.

[0098] When the above-mentioned function is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or a part of this technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in various embodiments of this application. The foregoing storage medium includes: various media such as USB flash drives, mobile hard disks, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical discs that can store program codes.

[0099] As described above, the above is only the specific implementation manner of this application, but the protection scope of this application is not limited thereto. Any person skilled in the art within the technical scope disclosed by this application can easily think of changes or substitutions, which should all be covered within the protection scope of this application. Therefore, the protection scope of this application should be subject to the protection scope of the claimed rights.

Claims

1. An electrochemical sensor for measuring liquid conductivity and dielectric constant, characterized in that: include: A probe, the probe comprising a first electrode sheet, a second electrode sheet and a third electrode sheet arranged in sequence, wherein the first electrode sheet close to the sensor and the second electrode sheet are connected via two electrode posts, and the third electrode sheet at the outermost side of the sensor is connected to the second electrode sheet via one electrode post; A measuring circuit, the measuring circuit comprising an RC circuit, an amplifier circuit, a comparison circuit and a NOT gate circuit, the RC circuit is used to measure a voltage change of a liquid, the amplifier circuit is used to amplify the voltage change of the RC circuit to obtain a first voltage u1, the comparison circuit is used to compare the first voltage u1 output by the amplifier circuit with 0 to obtain a third voltage u3, and the NOT gate circuit is used to compare the third voltage u3 with a second voltage u2 applied to the measuring circuit to obtain a fourth voltage u4, The duration of the high level of the fourth voltage u4 is the first time t1, and the duration of the low level of the fourth voltage u4 is the second time t2. The first time t1 and the second time t2 are used to determine the conductivity and the dielectric constant. The conductivity is determined by the following formula: Wherein, k is the conductivity, l is the distance between the first electrode sheet, the second electrode sheet and the third electrode sheet; A is the surface area of ​​the electrode plate; C is the known capacitance; The dielectric constant is obtained by the following formula: Among them, ε r is the dielectric constant, k is the conductivity, and ε0 is the dielectric constant in vacuum.

2. The electrochemical sensor according to claim 1, characterized in that The liquid includes at least one of oil, methanol, and ultrapure water, and the oil includes at least one of lubricating oil, hydraulic oil, and transformer oil.

3. The electrochemical sensor according to claim 1 or 2, characterized in that: The third electrode sheet is a reference electrode, and the first electrode sheet and the second electrode sheet are a working electrode and an auxiliary electrode, respectively.

4. The electrochemical sensor according to claim 1 or 2, characterized in that: The electrochemical sensor further comprises a self-cleaning module, which is used to release acetone or ethylene glycol to clean the sensor probe after the electrochemical sensor measures.

5. The electrochemical sensor according to claim 1 or 2, characterized in that: The electrochemical sensor is also used to measure the temperature of the liquid.

6. A liquid online monitoring system, characterized in that: The liquid online monitoring system comprises a sensor module, and the sensor module comprises the electrochemical sensor according to any one of claims 1 to 5.

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