An ethylbenzene gas sensor, detection system, and detection method

Abstract

The application relates to the technical field of electrochemical sensors, in particular to an ethylbenzene gas sensor, a detection system and a detection method, wherein the sensor comprises a support part for carrying a sensitive layer and / or an electrode; the sensitive layer is made of Zn-Co3O4 and forms a mutually interlaced nanorod structure; the resistance of the sensitive layer is more affected by ethylbenzene than other VOCs gases; and two electrodes are respectively electrically connected to two ends of the sensitive layer and are used for transmitting electric energy to the sensitive layer. The detection system and the detection method provided by the application perform interpolation calculation on a standard temperature-resistance-concentration surface according to real-time resistance and real-time temperature to obtain real-time concentration, effectively avoid measurement errors caused by the resistance baseline drift of the sensitive layer, and judge whether the data is reliable by calculating the stability of the interpolation concentration, so that the subsequent analysis and decision are avoided by using inaccurate data, and the accuracy and reliability of the detection result are improved.

Description

Technical Field

[0001] This invention relates to the field of electrochemical sensor technology, specifically to an ethylbenzene gas sensor, detection system, and detection method. Background Technology

[0002] Ethylbenzene, also known as ethylbenzene, has the chemical formula C8H. 10 Ethylbenzene is an important organic compound used not only in the production of styrene but also as a solvent, diluent, and in the production of diethylbenzene and acetophenone. Ethylbenzene has a low boiling point, is highly volatile, flammable, and strongly irritates human skin and mucous membranes, posing a health hazard. Therefore, in production enterprises using ethylbenzene as a raw material or in the synthesis of ethylbenzene, it is necessary to monitor the concentration of ethylbenzene in the air in real time to prevent safety accidents or injuries to workers.

[0003] Currently, the detection of ethylbenzene mostly utilizes photoionization sensors. The principle is to excite the molecules of VOCs (Volatile Organic Compounds) by ultraviolet light. The electrons of the VOCs gas molecules are excited and transition to different energy levels, generating negatively charged electrons and positively charged ions. The detector collects the ions and analyzes the concentration of VOCs gas in the air by analyzing the current of the ions.

[0004] Photoionization sensors can detect the concentration of various VOCs, but they lack specificity for any particular VOC component and cannot perform targeted detection for a single VOC. In actual manufacturing environments, whether using ethylbenzene as a raw material or as a product or intermediate, other VOCs are present in the air besides ethylbenzene. The value output by the photoionization sensor represents the total concentration of all ionizable VOCs. When used for air quality monitoring, it cannot distinguish between excessive ethylbenzene and excessive concentrations of other relatively harmless VOCs, potentially triggering unnecessary alarms or even production shutdowns, resulting in economic losses and wasted data. Conversely, if the concentration of ethylbenzene in the air is high, while the concentrations of other co-existing VOCs are low, the total VOC reading may not reach the alarm threshold, potentially masking a genuine safety hazard. Summary of the Invention

[0005] To address the technical problem that existing technologies cannot specifically measure ethylbenzene concentration, this application provides an ethylbenzene gas sensor, detection system, and detection method, wherein the sensor includes: a support, a sensitive layer, and two electrodes;

[0006] The support portion is used to support the sensitive layer and / or the electrode;

[0007] The sensitive layer is made of an interlaced nanorod structure formed by Zn-Co3O4, and the resistance of the sensitive layer is greater for ethylbenzene than for other VOCs gases.

[0008] The two electrodes are electrically connected to the two ends of the sensitive layer, and the electrodes are used to transmit electrical energy to the sensitive layer.

[0009] The detection system includes the aforementioned ethylbenzene gas sensor, temperature sensor, ADC module, and data processor;

[0010] The temperature sensor is used to measure the temperature of the ethylbenzene gas sensor;

[0011] The ADC module is used to perform high-frequency discrete sampling of analog signals to obtain the real-time resistance and real-time temperature of the ethylbenzene gas sensor.

[0012] The data processor is used to calculate the real-time concentration of ethylbenzene based on real-time resistance, real-time temperature, and a standard resistance-temperature-concentration surface.

[0013] The detection method includes the following steps:

[0014] The sensitive layer is heated, and its real-time resistance is collected at multiple different sampling temperatures.

[0015] Interpolate the standard resistance-temperature-concentration surface based on the real-time resistance corresponding to different sampling temperatures to obtain multiple interpolated concentrations. The standard resistance-temperature-concentration surface refers to the resistance values ​​of the sensitive layer calibrated at different concentrations and temperatures in the experimental environment.

[0016] Calculate the mean square error of multiple interpolated concentrations, determine whether the mean square error is greater than the stability threshold, if not, calculate the average value of multiple interpolated concentrations as the real-time concentration, if so, cool the sensitive layer and re-collect the real-time resistance at each sampling temperature.

[0017] The root mean square error of the newly sampled interpolated concentrations is recalculated. It is then determined whether the root mean square error is greater than the stability threshold. If not, the average value of the new interpolated concentrations is calculated as the real-time concentration. If so, the data is invalid and a warning is issued.

[0018] The technical effects and advantages of this invention are as follows: The sensitive layer of this application is a pn heterostructure nanocomposite material with a hierarchical porous structure formed by Zn-Co3O4. Its resistance value can specifically respond to the concentration change of ethylbenzene in the air, thereby realizing the determination of the concentration of ethylbenzene. The detection system and detection method provided by this invention calculate the real-time concentration by interpolating the standard temperature-resistance-concentration surface based on the real-time resistance and real-time temperature, effectively avoiding the measurement error caused by the resistance baseline drift of the sensitive layer. At the same time, the reliability of the data is judged by calculating the stability of the interpolated concentration, thereby avoiding the use of inaccurate data for subsequent analysis and decision-making, and improving the accuracy and reliability of the detection results. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the overall structure of the sensor of the present invention.

[0020] Figure 2 This is a SEM image of the sensitive layer Zn-Co3O4 of this invention.

[0021] Figure 3 The temperature curve of the ethylbenzene oxidation reaction in the sensitive layer of this invention is shown.

[0022] Figure 4 This is a diagram showing the response of the sensitive layer of the present invention to different VOCs gases.

[0023] Figure 5 This is a schematic diagram of the detection system of the present invention.

[0024] Figure 6 This is a flowchart of the detection method used in the detection system of the present invention.

[0025] Figure 7 This is a flowchart illustrating the calculation of real-time resistance in the detection method of the present invention.

[0026] Figure 8 This is the ethylbenzene concentration-resistance change curve of the sensitive layer of the present invention.

[0027] The attached figures are labeled as follows: 1. Support component; 2. Sensitive layer; 3. Electrode; 4. Heating unit; 5. Temperature sensor; Detailed Implementation

[0028] 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, and 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.

[0029] Existing technologies for measuring the concentration of VOCs such as ethylbenzene rely on the electrochemical properties of the benzene ring or CH bond to measure the concentration of VOCs, and cannot specifically measure the concentration of ethylbenzene alone. This makes it difficult for ethylbenzene production enterprises to meet the needs of monitoring the concentration of ethylbenzene in the air.

[0030] Example 1

[0031] This application provides an ethylbenzene gas sensor capable of specifically detecting the concentration of ethylbenzene gas in the air. (Reference) Figure 1 The sensor includes: a support 1, a sensitive layer 2, and two electrodes 3.

[0032] The support 1 is used to support the sensitive layer 2 and / or the electrode 3. The material of the sensitive layer 2 is Zn-Co3O4 (zinc-doped cobalt tetroxide). The resistance of the sensitive layer 2 is only affected by the oxidation reaction of ethylbenzene. The two electrodes 3 are electrically connected to the two ends of the sensitive layer 2 respectively. The electrodes 3 are used to transmit electrical energy to the sensitive layer 2 so as to measure the resistance of the sensitive layer 2.

[0033] Research has found that when ethylbenzene reacts with oxygen in the air under the catalysis of Zn-Co3O4, the generated electrons interact with the charge carriers in Zn-Co3O4, thereby changing the resistance of Zn-Co3O4. Therefore, the concentration of ethylbenzene in the air can be determined by measuring the change in resistance of Zn-Co3O4.

[0034] Based on the above research results, the sensitive layer 2 of this application adopts a pn heterostructure nanocomposite material with a hierarchical porous structure formed by Zn-Co3O4. This material contains p-type semiconductor cobalt oxide (Co3O4) nanorods and n-type semiconductor zinc oxide (ZnO) nanoparticles.

[0035] Co3O4 nanorods, used as the matrix material, are synthesized and precisely controlled to form an interlocking nanorod structure. ZnO nanoparticles are grown in situ on the surface of the Co3O4 nanorods, resulting in a well-defined and densely packed Co3O4 / ZnO heterostructure pn structure between the Co3O4 nanorods and ZnO nanoparticles. The band bending effect at the pn junction interface of this heterostructure generates a built-in electric field within the material, with a built-in potential difference of approximately 0.5 eV to 0.8 eV. When the target gas ethylbenzene molecules are adsorbed and undergo a redox reaction with oxygen adsorbates on the material surface—for example, ethylbenzene reacts with adsorbed oxygen (O⁻ or O²⁻) to generate C₂O and H₂O—a significant change in the carrier concentration on the surface of the sensitive layer 2 occurs. For p-type semiconductor Co3O4, when ethylbenzene molecules react with adsorbed oxygen as a reducing gas, they release electrons that are captured by Co3O4, leading to a decrease in the hole concentration inside Co3O4 and a corresponding increase in resistance. For n-type semiconductor ZnO, the electron concentration increases and the resistance decreases when reacting with a reducing gas. At the pn heterojunction interface, when ethylbenzene molecules are adsorbed and undergo oxidation, the barrier height of the heterojunction changes significantly, resulting in a drastic change in the carrier concentration and resistance of the sensitive layer 2, thereby greatly improving the sensor's sensitivity to ethylbenzene.

[0036] The aforementioned sensitive layer 2 is prepared through the following steps:

[0037] 1) Preparation of Zn-Co3O4 solution: Urea, ammonium fluoride, cobalt nitrate, Zn(NO3)2·6H2O, sodium citrate and deionized water were mixed in a mass ratio of 0.006:0.296:0.366:0.00846:0.00774:36 and stirred at room temperature for 30 min to ensure that all components were fully dissolved in the deionized water;

[0038] 2) Add the prepared Zn-Co3O4 solution into a Teflon dust tube, place the Teflon dust tube in a stainless steel autoclave, maintain at 110℃ for 9 h, and then cool to room temperature;

[0039] 3) Wash the Zn-Co3O4 powder repeatedly with deionized water and ethanol;

[0040] 4) Dry the cleaned Zn-Co3O4 powder at 80℃ for 6 hours;

[0041] 5) Anneal at 450℃ for 2 h to obtain Zn-Co3O4 powder;

[0042] 6) Zn-Co3O4 powder was prepared on the support 1 by hydrothermal method to complete the preparation of the sensitive layer 2.

[0043] Figure 2The image shows a SEM image of the sensitive layer 2 prepared by the above steps. It can be seen from the image that the Zn-Co3O4 crystals are distributed in a cross-shaped nanorod pattern. The spaces between each nanorod can accommodate ethylbenzene molecules, thereby increasing the contact area between ethylbenzene and Zn-Co3O4 crystals.

[0044] The support portion 1 of the sensor of the present invention can be made of alumina ceramic, silicon nitride ceramic, or quartz glass. These materials have excellent high-temperature resistance, chemical stability, and insulation properties. A thin and dense silicon dioxide or titanium dioxide buffer layer can also be deposited on the surface of the support portion 1 by physical vapor deposition (PVD) or chemical vapor deposition (CVD) to optimize its surface roughness and wettability. In particular, it can improve the adhesion strength of the subsequent sensitive layer 2, ensuring that the sensitive layer 2 can be uniformly and firmly grown or deposited on it.

[0045] The two electrodes 3 of the aforementioned sensor can be platinum electrodes 3. Platinum has excellent conductivity and chemical stability. Electrodes 3 can be deposited on the support 1 adjacent to the sensitive layer 2 using magnetron sputtering technology, ensuring reliable electrical contact between the electrodes 3 and the sensitive layer 2. The two electrodes 3 can have leads extended from the support 1 for connecting to a power supply.

[0046] Figure 3 The oxidation rate of ethylbenzene on the sensitive layer 2 at different temperatures is shown. Although ethylbenzene undergoes oxidation at room temperature, the reaction rate is very slow, and the change in resistance of the sensitive layer 2 is not significant. As the temperature increases, the oxidation rate of ethylbenzene accelerates. Therefore, the ethylbenzene sensor provided in this application also includes a heating unit 4 for raising the temperature of the sensitive layer 2. A typical option for the heating unit 4 is a heating wire, specifically, the heating wire is disposed on the side of the support 1 away from the sensitive layer 2.

[0047] By controlling the temperature of the sensitive layer 2, the rate of the ethylbenzene oxidation reaction can be increased, making the resistance change of the sensitive layer 2 more significant, thereby improving the sensor's detection sensitivity and response speed for ethylbenzene. When the heating wire is energized, the generated heat can be quickly and evenly transferred to the support part 1, thus affecting the temperature of the sensitive layer 2.

[0048] The table below shows the performance comparison test of the sensor provided in this application. Compared with the sensor with only Co3O4, it can be seen that the sensor doped with Zn exhibits specific recognition of ethylbenzene.

[0049]

[0050] Figure 4 The test results of the sensor's response to different VOCs gases are shown. It can be seen that the response to ethylbenzene is significantly higher than that to other VOCs gases.

[0051] Example 2

[0052] Based on the above-mentioned ethylbenzene gas sensor, the present invention also provides an ethylbenzene gas detection system for measuring the concentration of ethylbenzene in the air, reference... Figure 5 The system includes: the aforementioned ethylbenzene gas sensor, temperature sensor 5, ADC module, power supply, data processor, and host computer and / or display.

[0053] The power supply provides power to the ethylbenzene gas sensor, temperature sensor 5, ADC module, data processor, and host computer.

[0054] Temperature sensor 5 is used to measure the temperature of the sensitive layer 2 of the ethylbenzene gas sensor;

[0055] The ADC module is used to perform high-frequency discrete sampling of analog signals, convert analog signals into digital signals, and transmit digital signals to the data processor to obtain the real-time resistance and real-time temperature of the ethylbenzene gas sensor.

[0056] The data processor is used to calculate the real-time concentration of ethylbenzene based on real-time resistance, real-time temperature, and a standard resistance-temperature-concentration surface, and to send the data to the host computer and / or display based on the real-time concentration.

[0057] Temperature sensor 5 can be a thin-film resistance thermometer, such as MZBB-7A platinum thin-film resistance thermometer, which is made based on the fundamental characteristic that the resistance of platinum material changes with absolute temperature. It is made by depositing metallic platinum on a ceramic substrate using thin-film technology and then processing it through photolithography, ion beam etching, laser trimming, etc. It has a "sandwich" structure of three layers: ceramic substrate, sensitive platinum film, and glass encapsulation. It has the characteristics of high precision, small size, strong vibration resistance, and high reliability, and is suitable for integration into small-volume sensors. It is suitable for measuring the temperature of the sensitive layer 2 of the ethylbenzene gas sensor provided by this invention.

[0058] When it is necessary to measure the concentration of ethylbenzene in the air, the heating unit 4 of the ethylbenzene sensor starts to heat the sensitive layer 2, and the temperature sensor 5 measures the temperature of the sensitive layer 2 in real time. When the temperature of the sensitive layer 2 reaches the preset sampling threshold, the two electrodes 3 of the ethylbenzene sensor are energized to the sensitive layer 2 to measure the real-time resistance of the sensitive layer 2. The real-time concentration of ethylbenzene is calculated based on the real-time resistance of the sensitive layer 2.

[0059] Specifically, refer to Figure 6 The real-time concentration of ethylbenzene is obtained through the following steps:

[0060] S1. Heat the sensitive layer 2 and collect the real-time resistance of the sensitive layer 2 at multiple different sampling temperatures;

[0061] Specifically, refer to Figure 7 The real-time resistance is obtained through the following steps:

[0062] S11. Heat the sensitive layer 2 and periodically measure the real-time temperature of the sensitive layer 2;

[0063] S12. When the real-time temperature reaches the sampling temperature, the temperature of the sensitive layer 2 is controlled to remain at the sampling temperature.

[0064] S13. Determine whether the real-time temperature is stable. If so, supply power to the sensitive layer 2 and periodically measure the sampling resistance of the sensitive layer 2.

[0065] S14. Determine whether the sampling resistor is stable. If so, calculate the average value of multiple sampling resistors as the real-time resistance corresponding to the current sampling temperature.

[0066] During the sampling process, the temperature of the sensitive layer 2 fluctuates due to the PID control method used for the heating component. Simultaneously, the ADC module performs high-speed discrete sampling of the analog signal, resulting in discrete values ​​with inherent fluctuations. Therefore, a stability check is performed on the real-time temperature, and the resistance of the sensitive layer 2 is sampled only when the real-time temperature stabilizes. Similarly, the stability of the sampled resistance value is also checked, and the real-time resistance is calculated based on multiple sampled resistance values ​​to mitigate the impact of fluctuations on the measurement results.

[0067] Whether the real-time temperature and the sampling resistance are stable can be determined by their respective mean square errors. Calculate the mean square errors of multiple real-time temperatures, and if the mean square error is less than the stability threshold, then the real-time temperature is considered stable.

[0068] When conducting stability evaluations, the values ​​involved in the calculations can be normalized to facilitate the setting of a uniform stability threshold, thereby reducing the difficulty of system deployment and application. Specifically, the normalization of real-time temperatures can be achieved by setting the maximum value among multiple real-time temperatures to 1, and modifying the other real-time temperatures to their corresponding values ​​based on their ratios to the maximum value.

[0069] The normalization of the sampling resistor can also be done in the same way.

[0070] S2. Interpolate the standard resistance-temperature-concentration surface based on the real-time resistance at different sampling temperatures to obtain multiple interpolated concentrations, wherein the standard resistance-temperature-concentration surface is the resistance value of the sensitive layer 2 at different concentrations and temperatures calibrated in the experimental environment.

[0071] Specifically, the standard resistance-temperature-concentration surface can be obtained through the following steps:

[0072] S21. Continuously change the concentration of ethylbenzene and the temperature of sensitive layer 2 in the experimental environment, and collect the real-time resistance of sensitive layer 2 at different ethylbenzene concentrations and different temperatures.

[0073] S22. Construct a three-dimensional space of resistance-temperature-concentration with sampling temperature as the x-axis, real-time resistance as the y-axis, and ethylbenzene concentration as the z-axis. Form a standard resistance-temperature-concentration surface through polynomial fitting.

[0074] Since the composition of gases in the air can be artificially controlled in the laboratory environment, the resistance of the sensitive layer 2 can be calibrated in the laboratory at different ethylbenzene concentrations and temperatures. A standard resistance-temperature-concentration surface can then be formed through polynomial fitting, thus providing a basis for assessing the concentration of ethylbenzene in the environment. The measurement results of this method are related to the scale of the experimental data used to fit the standard resistance-temperature-concentration surface. When there is a large amount of experimental data to fit the standard resistance-temperature-concentration surface, the measurement results provided by this method are more accurate than those provided by traditional empirical formulas.

[0075] Figure 8 The resistance variation curves of sensitive layer 2 under different ethylbenzene concentrations are shown. It can be seen that the resistance of sensitive layer 2 increases with the increase of ethylbenzene concentration. Furthermore, the resistance value of sensitive layer 2 changes gradually during the response process.

[0076] Furthermore, considering factors such as baseline drift, the standard resistance-temperature-concentration surface can also be obtained through the following steps:

[0077] S23. Keep the experimental environment clean, that is, there are no VOCs gases including ethylbenzene in the air. Heat the sensitive layer 2 and collect the real-time resistance of the sensitive layer 2 at multiple different sampling temperatures as the baseline resistance.

[0078] S24. Continuously change the concentration of ethylbenzene and the temperature of sensitive layer 2 in the experimental environment, and collect the real-time resistance of sensitive layer 2 at different ethylbenzene concentrations and different temperatures.

[0079] S25. Subtract the baseline resistance measured at the same temperature from the real-time resistance to obtain the difference resistance corresponding to different ethylbenzene concentrations at each sampling temperature;

[0080] S26. Construct a three-dimensional space of resistance-temperature-concentration with sampling temperature as the x-axis, differential resistance as the y-axis, and ethylbenzene concentration as the z-axis. Form a standard resistance-temperature-concentration surface through polynomial fitting.

[0081] The temperature-resistance data of the sensitive layer 2 under clean air can be used to calibrate the baseline resistance of the sensitive layer 2 itself. When constructing the standard resistance-temperature-concentration surface, the measured real-time resistance can be subtracted from the baseline resistance, thereby eliminating the influence of the characteristics of the sensitive layer 2 itself on the measurement results, so that the obtained standard resistance-temperature-concentration surface more accurately reflects the relationship between ethylbenzene concentration and resistance and temperature.

[0082] When using this standard resistance-temperature-concentration surface for ethylbenzene concentration detection, the baseline resistance can be subtracted from the measured real-time resistance, and the corresponding ethylbenzene concentration value can be found on the surface using interpolation. This improves the accuracy and reliability of the detection and reduces errors caused by differences in the characteristics of the sensitive layer 2 itself.

[0083] S3. Calculate the mean square error of multiple interpolated concentrations and determine whether the mean square error is greater than the stability threshold. If not, calculate the average value of multiple interpolated concentrations as the real-time concentration. If so, cool down the sensitive layer 2 and re-collect the real-time resistance at each sampling temperature.

[0084] Specifically, cooling can be achieved by turning off the heating unit 4 and allowing the sensitive layer 2 to cool down naturally, or by setting up a cooling fan to force convection and quickly cool down the sensitive layer 2.

[0085] S4. Recalculate the mean square error of the multiple interpolated concentrations of the new samples, and determine whether the mean square error is greater than the stability threshold. If not, calculate the average value of the multiple interpolated concentrations as the real-time concentration. If so, indicate that the data is invalid and issue a warning.

[0086] When the standard deviation (SD) is less than or equal to the stability threshold, the interpolated concentration is sufficiently stable, and the measurement error meets the accuracy requirements. When the SD is greater than the stability threshold, the interpolated concentration is unstable, the measurement results fluctuate significantly, the accuracy is insufficient, and interference exists. Therefore, correction is required. By lowering the temperature of sensitive layer 2, real-time resistance is re-acquired at different sampling temperatures, interpolation is performed again, and the SD of the interpolated concentration is calculated. When the difference concentration from the two acquisitions fails to meet the stability requirements, it indicates that there is unavoidable interference in the environment or a malfunction in the sensor itself. Therefore, the measured data cannot be used to determine the concentration of ethylbenzene in the air.

[0087] Similarly, when calculating the root mean square error of multiple interpolated concentrations, the interpolated concentrations can be normalized. The specific processing method is the same as that for real-time temperature, so as to use a uniform stability threshold to determine stability.

[0088] The above method calculates real-time concentration by interpolation based on real-time resistance and temperature. When the standard temperature-resistance-concentration surface itself has sufficient accuracy, interpolation can obtain sufficiently accurate results. Simultaneously, the interpolation method effectively avoids measurement errors caused by baseline drift of the sensitive layer 2's resistance. During long-term use, the baseline of sensitive layer 2 may drift due to environmental factors, material aging, etc., which can affect the accuracy of measurement results. This method, by acquiring real-time resistance at multiple different sampling temperatures and performing interpolation calculations, uses multiple data points to determine the real-time concentration. Even if a certain degree of baseline drift occurs in sensitive layer 2, the interpolation algorithm can correct and compensate for this drift to a certain extent, thereby ensuring the accuracy and reliability of the measurement results.

[0089] Furthermore, by repeatedly assessing the relationship between the mean square error and the stability threshold, the stability of the measurement results can be further ensured. When the mean square error is greater than the stability threshold, it indicates a large degree of dispersion in the measurement data, potentially indicating significant errors. In this case, cooling the sensitive layer 2 and re-collecting data can effectively eliminate interference from abnormal data, making the measurement results more stable and accurate. Moreover, if the mean square error remains greater than the stability threshold after multiple attempts, an invalid data indication and warning are issued, promptly alerting operators to potential problems during the measurement process and preventing the use of inaccurate data for subsequent analysis and decision-making.

[0090] In conclusion, the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An ethylbenzene gas sensor, characterized in that, It includes a support, a sensitive layer, and two electrodes: The support portion is used to support the sensitive layer and / or the electrode; The sensitive layer is made of an interlaced nanorod structure formed by Zn-Co3O4, and the resistance of the sensitive layer is greater for ethylbenzene than for other VOCs gases. The two electrodes are respectively electrically connected to both ends of the sensitive layer, and the electrodes are used to transmit electrical energy to the sensitive layer; The sensitive layer is prepared by the following steps: 1) Preparation of Zn-Co3O4 solution: Urea, ammonium fluoride, cobalt nitrate, Zn(NO3)2·6H2O, sodium citrate and deionized water were mixed in a mass ratio of 0.006:0.296:0.366:0.00846:0.00774:36 and stirred at room temperature for 30 min to ensure that all components were fully dissolved in the deionized water; 2) Add the prepared Zn-Co3O4 solution into a Teflon dust tube, place the Teflon dust tube in a stainless steel autoclave, maintain at 110℃ for 9 h, and then cool to room temperature; 3) Wash the Zn-Co3O4 powder repeatedly with deionized water and ethanol; 4) Dry the cleaned Zn-Co3O4 powder at 80℃ for 6 hours; 5) Anneal at 450℃ for 2 h to obtain Zn-Co3O4 powder; 6) Zn-Co3O4 powder is prepared on the support using a hydrothermal method to complete the preparation of the sensitive layer.

2. The sensor according to claim 1, characterized in that, The sensor also includes a heating unit for increasing the temperature of the sensitive layer to accelerate the oxidation reaction of ethylbenzene in contact with the sensitive layer.

3. An ethylbenzene detection system, comprising the sensor of claim 1, characterized in that, Also includes: Temperature sensor, ADC module, and data processor; The temperature sensor is used to measure the temperature of the ethylbenzene gas sensor; The ADC module is used to perform high-frequency discrete sampling of analog signals to obtain the real-time resistance and real-time temperature of the ethylbenzene gas sensor. The data processor is used to calculate the real-time concentration of ethylbenzene based on real-time resistance, real-time temperature, and a standard resistance-temperature-concentration surface.

4. The system according to claim 3, characterized in that, The real-time concentration of ethylbenzene is obtained through the following steps: The sensitive layer is heated, and its real-time resistance is collected at multiple different sampling temperatures. Interpolate the standard resistance-temperature-concentration surface based on the real-time resistance corresponding to different sampling temperatures to obtain multiple interpolated concentrations. The standard resistance-temperature-concentration surface refers to the resistance values ​​of the sensitive layer calibrated at different concentrations and temperatures in the experimental environment. Calculate the mean square error of multiple interpolated concentrations, determine whether the mean square error is greater than the stability threshold, if not, calculate the average value of multiple interpolated concentrations as the real-time concentration, if so, cool the sensitive layer and re-collect the real-time resistance at each sampling temperature. The root mean square error of the newly sampled interpolated concentrations is recalculated. It is determined whether the root mean square error is greater than the stability threshold. If not, the average value of the new interpolated concentrations is calculated as the real-time concentration. If so, the data is invalid and a warning is issued.

5. The system according to claim 4, characterized in that, Obtain the real-time resistance using the following steps: The sensitive layer is heated, and the real-time temperature of the sensitive layer is measured periodically. When the real-time temperature reaches the sampling temperature, the temperature of the sensitive layer is controlled to remain at the sampling temperature. Determine whether the real-time temperature is stable. If so, supply power to the sensitive layer and periodically obtain the sampling resistance of the sensitive layer. Determine if the sampling resistor is stable. If so, calculate the average value of multiple sampling resistors as the real-time resistance corresponding to the current sampling temperature.

6. The system according to claim 5, characterized in that, The following steps are used to determine whether the real-time temperature is stable: The system normalizes multiple real-time temperatures, selects the one with the largest value from the multiple real-time temperatures, sets its value to 1, and modifies the other real-time temperatures according to their ratio to the largest value. Calculate the mean square error of the real-time temperatures after multiple normalization processes, and determine whether the mean square error is greater than the stability threshold. If not, the real-time temperature is determined to be stable.

7. The system according to claim 4, characterized in that, The standard resistance-temperature-concentration surface is obtained through the following steps: In an air environment free of VOCs, including ethylbenzene, the sensitive layer is heated, and the real-time resistance of the sensitive layer is collected at multiple different sampling temperatures as a baseline resistance. The concentration of ethylbenzene and the temperature of the sensitive layer in the experimental environment were continuously changed, and the real-time resistance of the sensitive layer was collected at different ethylbenzene concentrations and different temperatures. Subtract the baseline resistance measured at the same temperature from the real-time resistance to obtain the differential resistance corresponding to different ethylbenzene concentrations at each sampling temperature; Using sampling temperature as the first coordinate axis, differential resistance as the second coordinate axis, and ethylbenzene concentration as the third coordinate axis, a three-dimensional space of resistance-temperature-concentration is constructed, and the standard resistance-temperature-concentration surface is formed by polynomial fitting.

8. A detection method, employing the system according to any one of claims 3-7, for measuring the concentration of ethylbenzene gas in air, characterized in that, Includes the following steps: The sensitive layer is heated, and its real-time resistance is collected at multiple different sampling temperatures. Interpolate the standard resistance-temperature-concentration surface based on the real-time resistance corresponding to different sampling temperatures to obtain multiple interpolated concentrations. The standard resistance-temperature-concentration surface refers to the resistance values ​​of the sensitive layer calibrated at different concentrations and temperatures in the experimental environment. Calculate the mean square error of multiple interpolated concentrations, determine whether the mean square error is greater than the stability threshold, if not, calculate the average value of multiple interpolated concentrations as the real-time concentration, if so, cool the sensitive layer and re-collect the real-time resistance at each sampling temperature. The root mean square error of the newly sampled interpolated concentrations is recalculated. It is determined whether the root mean square error is greater than the stability threshold. If not, the average value of the new interpolated concentrations is calculated as the real-time concentration. If so, the data is invalid and a warning is issued.

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