CO2 detection device and system based on YSZ sensor and plasma generator

Abstract

The invention belongs to the field of gas detection, and particularly relates to a CO2 detection device and system based on a YSZ sensor and a plasma generator, and the CO2 detection device comprises the plasma generator, a test chamber and the YSZ sensor; the YSZ sensor is arranged in the test chamber; the YSZ sensor comprises a YSZ solid electrolyte layer, a reference electrode and a sensitive electrode; the reference electrode and the sensitive electrode are arranged on the surface of the YSZ solid electrolyte layer at an interval, and the material of the sensitive electrode is Bi2Mn4O10; the plasma generator is connected to the air inlet end of the test chamber. Compared with the prior art, the defects that in the prior art, a YSZ sensor is insufficient in CO2 selectivity and low in response speed are overcome. According to the scheme, plasma treatment is matched with the YSZ sensor, the target gas CO2 is converted into a form easier to detect through plasma treatment, the detection accuracy and reliability are improved, meanwhile, interference gas is selectively ionized and decomposed, and interference is reduced.

Description

Technical Field

[0001] The invention belongs to the field of gas detection, and in particular relates to a CO2 detection device and system based on a YSZ sensor and a plasma generator. Background Art

[0002] Carbon dioxide (CO2), as an important greenhouse gas, plays an increasingly prominent role in global climate change. With the acceleration of industrialization and the continuous growth of population, CO2 emissions have shown a significant upward trend. This not only exacerbates the greenhouse effect, leading to rising global temperatures, rising sea levels and frequent extreme weather, but also has a profound impact on the ecosystem. For example, the absorption of a large amount of CO2 by the ocean leads to seawater acidification, which seriously threatens the living environment of marine life. In addition, the increase in CO2 concentration also poses a potential threat to human health, especially in closed environments such as homes, offices and medical institutions. Excessive CO2 concentrations may cause health problems such as headaches, lack of concentration, shortness of breath, and even endanger life in extreme cases.

[0003] In the medical field, CO2 detection has important clinical application value. By analyzing the CO2 concentration in human exhaled breath, the individual's respiratory function and metabolic status can be evaluated, which is of great significance in disease diagnosis, sports medicine and vital signs monitoring. For example, respiratory physicians can judge the patient's respiratory efficiency and lung function by the change of CO2 concentration, and athletes can optimize their training programs by monitoring CO2 emissions. In addition, with the improvement of personal health management awareness, the demand for portable CO2 detection equipment is also growing to meet the needs of daily health monitoring and environmental assessment.

[0004] At present, CO2 detection technologies mainly include infrared spectroscopy, electrochemical method, solid electrolyte sensor and surface acoustic wave (SAW) sensor. Infrared spectroscopy has been widely used in CO2 detection due to its high accuracy and high selectivity. This method determines the concentration of CO2 molecules by measuring their absorption of infrared light of a specific wavelength. However, infrared spectroscopy equipment is usually bulky, expensive, and sensitive to changes in ambient humidity and temperature, which limits its application in portable devices.

[0005] Electrochemical sensors have become another important technology in the field of CO2 detection due to their simple structure, low cost and easy integration. Traditional electrochemical sensors detect gas concentrations through electrochemical reactions between electrodes and electrolytes. However, electrochemical sensors often face problems such as poor selectivity and susceptibility to humidity and temperature in practical applications. Especially in complex gas environments, the presence of other volatile organic compounds (VOCs) and interfering gases can significantly affect the accuracy and reliability of the sensor.

[0006] Solid electrolyte sensors based on yttria stabilized zirconia (Yttria Stabilized Zirconia, YSZ) have good performance in high temperature environments due to their high chemical stability and excellent ionic conductivity, and are widely used in fuel cells and gas sensors. YSZ sensors achieve gas detection through the migration of oxygen ions and have high selectivity and stability. For example, CN108195907A discloses an electrochemical sensor based on the photoelectric coupling effect and a preparation method thereof, which includes a YSZ solid electrolyte layer, a heating plate, a reference electrode and three sensitive electrodes. The three sensitive electrodes are respectively a first sensitive electrode, a second sensitive electrode and a third sensitive electrode. The material of the first sensitive electrode is zinc oxide, the material of the second sensitive electrode is a mixture of zinc oxide and iron oxide, and the mass of iron oxide in the mixture of zinc oxide and iron oxide is 20% of the mass of zinc oxide; the material of the third sensitive electrode is a mixture of zinc oxide and cerium oxide, and the mass of cerium oxide in the mixture of zinc oxide and cerium oxide is 30% of the mass of zinc oxide, and the material of the reference electrode is manganese dioxide.

[0007] However, traditional YSZ sensors still have certain limitations in terms of selectivity and response speed when measuring CO2. Especially as the application demand in complex gas environments continues to increase, there is an urgent need to improve and optimize existing sensing technologies. Summary of the invention

[0008] In recent years, plasma technology has been gradually introduced into the field of gas sensors because it can produce high-energy particles and free radicals, significantly improving the reactivity of gases. Plasma can effectively change the physical and chemical properties of gas molecules by ionizing gas molecules, thereby improving the sensor's ability to detect target gases. Combining plasma technology with traditional sensor technology is expected to achieve highly selective and sensitive gas detection in complex gas environments.

[0009] The purpose of the present invention is to provide a CO2 detection device and system based on a YSZ sensor and a plasma generator in order to solve at least one of the above problems, so as to solve the defects of the YSZ sensor in the prior art in terms of insufficient selectivity for CO2 and weak response speed (insensitivity). This solution uses plasma treatment in conjunction with a YSZ sensor. Through plasma treatment, the target gas (CO2) can be converted into a form (CO) that is easier to be detected by the YSZ sensor, thereby improving the accuracy and reliability of the detection, while selectively ionizing and decomposing interfering gases, reducing the interference of other gases on the YSZ sensor in a complex environment.

[0010] The purpose of the present invention is achieved through the following technical solutions:

[0011] The first aspect of the present invention discloses a CO2 detection device based on a YSZ sensor and a plasma generator, comprising a plasma generator, a test chamber and a YSZ sensor;

[0012] The YSZ sensor is arranged inside the test chamber;

[0013] The YSZ sensor comprises a YSZ solid electrolyte layer, a reference electrode and a sensitive electrode; the reference electrode and the sensitive electrode are arranged on the surface of the YSZ solid electrolyte layer at intervals, and the material of the sensitive electrode is Bi2Mn4O 10 ;

[0014] The plasma generator is connected to the gas inlet end of the test chamber and is used to ionize the gas to be tested.

[0015] Bi2Mn4O 10 As a sensitive electrode, the material is insensitive to CO2 and has poor selectivity to CO, but it is relatively sensitive to CO. Therefore, in this scheme, a device that can realize ionization is added to the air inlet end to convert CO2 in the gas into CO, and the background interference in the gas can be greatly removed by ionizing and decomposing the interfering gas, so as to realize the indirect determination of CO2 concentration, and finally achieve high selectivity for CO2 (removal of interference by ionization and decomposition) and high sensitivity response (based on Bi2Mn4O 10 High sensitivity to CO).

[0016] Preferably, the YSZ sensor also includes a heating plate; the reference electrode and the sensitive electrode are arranged on the first surface of the YSZ solid electrolyte layer, and the heating plate is arranged on the second surface of the YSZ solid electrolyte layer, and the first surface and the second surface are a pair of opposite surfaces of the YSZ solid electrolyte layer.

[0017] Preferably, the YSZ sensor is prepared by the following steps:

[0018] S1: printing a slurry containing a reference electrode material on a first surface of the YSZ solid electrolyte layer by screen printing, drying and sintering to form a reference electrode;

[0019] S2: printing a slurry containing a sensitive electrode material on a first surface of the YSZ solid electrolyte layer by screen printing, spacing it from a reference electrode, drying it and sintering it to form a sensitive electrode;

[0020] S3: Platinum slurry is applied on the surface of the reference electrode and the sensitive electrode, and electrode leads are drawn out from the platinum slurry respectively, and then sintered into shape after drying;

[0021] S4: bonding the heating sheet to the second surface of the YSZ solid electrolyte layer.

[0022] Preferably, in step S1, the slurry containing the reference electrode material is prepared by mixing the reference electrode material with pinene alcohol slurry and grinding them uniformly; in step S2, the slurry containing the sensitive electrode material is prepared by mixing the sensitive electrode material with pinene alcohol slurry and grinding them uniformly;

[0023] The terpineol slurry is formed by mixing terpineol and ethyl cellulose.

[0024] Preferably, in step S3, the sintering temperature is 700-1100°C.

[0025] More preferably, the sintering temperature is 850-950°C.

[0026] More preferably, the sintering temperature is 900°C.

[0027] Preferably, in step S4, the heating plate is bonded to the second surface of the YSZ solid electrolyte layer by a high temperature resistant adhesive.

[0028] Preferably, the material of the reference electrode is manganese dioxide.

[0029] Preferably, the material of the heating plate is aluminum oxide.

[0030] Preferably, the YSZ solid electrolyte layer and the heating plate are both in the shape of a cuboid, and the length and width of the YSZ solid electrolyte layer are equal to the length and width of the heating plate. The reference electrode and the sensitive electrode are respectively in the shape of a cuboid of the same size. A reference electrode lead is provided on the reference electrode, and a sensitive electrode lead is provided on the sensitive electrode.

[0031] Preferably, the length of the YSZ solid electrolyte layer and the heating plate ranges from 1.3 to 1.7 cm, and the width ranges from 2 to 3 cm. The thickness of the YSZ solid electrolyte layer ranges from 0.5 to 1 cm, and the thickness of the heating plate ranges from 1.1 to 1.5 mm.

[0032] Preferably, the reference electrode and the sensitive electrode have a length ranging from 4 to 6 mm, a width ranging from 4 to 6 mm, and a thickness ranging from 14 to 16 μm.

[0033] Preferably, the plasma generator comprises an input wire, a driver, an output wire and an ionization chamber;

[0034] One end of the input wire is connected to a DC power supply, and the other end of the input wire is connected to a driver;

[0035] The driver is used to convert the direct current input by the input wire into high-voltage alternating current and output it through the output wire;

[0036] One end of the output wire is connected to the driver, and the positive electrode and the negative electrode of the other end of the output wire are respectively connected to the inside and the outside of the ionization chamber to form a corona discharge;

[0037] One end of the ionization chamber is an air inlet end for introducing the gas to be tested; the other end of the ionization chamber is connected to the air inlet end of the test chamber for delivering the ionized gas to be tested into the test chamber.

[0038] Preferably, the driver comprises a push-pull inverter and a transformer connected to each other; the push-pull inverter is used to convert the input direct current into alternating current, and the transformer is used to increase the voltage amplitude of the alternating current to form high-voltage alternating current;

[0039] The ionization chamber is a quartz tube.

[0040] Preferably, the test chamber is a quartz tube;

[0041] The YSZ sensor is assembled on a sealing plug, and the sealing plug is installed at one end of the test chamber so that the YSZ sensor extends into the test chamber; the YSZ sensor is also connected to an output signal line, and the output signal line is led out from the test chamber through the sealing plug;

[0042] The other end of the test chamber is connected to a plasma generator.

[0043] Preferably, the sealing plug is a rubber plug.

[0044] The second aspect of the present invention discloses a CO2 detection system, which uses a CO2 detection device based on a YSZ sensor and a plasma generator as described in any of the above items to detect changes in CO2 concentration in an airflow, especially for highly selective detection of CO2 in human exhaled air.

[0045] The invention proposes a high CO2 detection device based on a YSZ sensor and a plasma generator, which can selectively detect CO2 in human exhaled breath: the device converts CO2 into CO through a plasma generator, selectively ionizes interfering gases, and utilizes Bi2Mn4O 10 The sensor made of the material has high sensitivity to CO, thereby indirectly achieving highly selective detection of CO2. This innovative design not only overcomes the problems of poor selectivity and slow response of traditional sensors in complex gas environments, but also improves the applicability and practicality of the sensor in portable devices.

[0046] Compared with the prior art, the present invention has the following beneficial effects:

[0047] At present, gas sensors based on yttria stabilized zirconia (YSZ or zirconium-based) electrolytes have attracted widespread attention due to their suitability for extreme environments (high temperature and high humidity), high selectivity and low cost. Among them, zirconium-based gas sensors equipped with oxide sensitive electrodes have been studied most intensively. However, there have been no reports on the highly selective detection of CO2 by existing zirconium-based sensors in mixed gas environments containing volatile organic compounds (VOCs). Moreover, when detecting CO2, traditional YSZ sensors often find it difficult to effectively suppress the influence of interfering gases such as VOCs, which limits the accuracy and reliability of the detection results.

[0048] The present invention proposes for the first time a highly selective detection device for CO2 in human exhaled breath. The device converts CO2 into CO through a plasma generator and uses Bi2Mn4O 10 The sensor made of the material has a highly selective response to CO, and can achieve highly selective detection of CO2 in human exhaled breath. At the same time, the device also selectively ionizes interfering gases such as VOCs in the mixed gas, thereby significantly reducing their response to the sensor. Compared with the prior art, the present invention effectively suppresses the response of interfering gases through innovative plasma processing technology, improves the detection accuracy and reliability of the sensor for CO2, and solves the limitations of traditional YSZ sensors in complex gas environments.

[0049] Specific:

[0050] 1. The present invention selectively ionizes interfering gases such as volatile organic compounds (VOCs) in the mixed gas through a plasma generator, and converts CO2 into CO. 10 The sensor has a highly selective characteristic for CO, and realizes highly selective detection of CO2 in human exhaled breath. This indirect detection method effectively avoids the problem that traditional YSZ sensors are affected by interfering gases in complex gas environments.

[0051] 2. By optimizing the microstructure and material selection of the sensor, the CO2 sensor of the present invention can achieve rapid gas diffusion and reaction processes, greatly shortening the detection response time. It is suitable for real-time monitoring of CO2 concentration changes in human exhaled air and meeting the needs of clinical and health monitoring.

[0052] 3. Use YSZ as the solid electrolyte layer, combined with Bi2Mn4O 10 The sensitive electrode material gives the sensor excellent chemical stability and temperature adaptability. The sensor can still maintain stable performance in high temperature and high humidity environments, ensuring reliability and consistency in long-term use.

[0053] 4. By testing the sensor at different calcination temperatures of 800℃, 900℃ and 1000℃, combined with response data analysis, 900℃ was determined to be the best working temperature. This temperature not only ensures the high sensitivity of the sensor to CO, but also effectively suppresses the response of interfering gases, achieving the best detection performance.

[0054] 5. The device of the present invention has a simple structure and uses low-cost materials and manufacturing processes, which is suitable for large-scale production and application in portable devices. The lightweight and miniaturized design of the sensor makes it easy to carry and operate, meeting the needs of personal health monitoring and mobile medical devices.

[0055] 6. Through Bi2Mn4O 10 The sensitive electrode has a highly selective response to CO, and the sensor can detect extremely low concentrations of CO, thereby indirectly achieving high-sensitivity detection of low concentrations of CO2.

[0056] 7. The sensor and plasma generator of the present invention are modularly designed, which is convenient for integration with other detection systems or intelligent devices to achieve multifunctional gas monitoring and data processing. In addition, the preparation method and material selection of the sensor have good scalability and can meet the needs of different application scenarios in the future.

[0057] 8. Since the present invention can efficiently and accurately detect the CO2 concentration in human exhaled air, it has a wide range of application prospects. In the fields of medical diagnosis, sports medicine, environmental monitoring and personal health management, it can provide reliable data support and promote the development and application of related technologies. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 It is a structural schematic diagram of the device of the present invention;

[0059] Figure 2 It is the structural diagram of the YSZ sensor;

[0060] Figure 3 The response value of the sensitive electrode of the YSZ sensor is tested for the mixed gas of ethanol, ethylbenzene, 2-heptanone, butanone, ammonia, CO, and CO2 (diluted to 16%) when the calcination temperature of the sensitive electrode in the YSZ sensor is 800℃ and the plasma generator is used and not used;

[0061] Figure 4 The response value of the sensitive electrode of the YSZ sensor is tested for the mixed gas of ethanol, ethylbenzene, 2-heptanone, butanone, ammonia, CO, and CO2 (diluted to 16%) when the calcination temperature of the sensitive electrode in the YSZ sensor is 900℃ and the plasma generator is used and not used;

[0062] Figure 5The response value of the sensitive electrode of the YSZ sensor is tested for the mixed gas of ethanol, ethylbenzene, 2-heptanone, butanone, ammonia, CO, and CO2 (diluted to 16%) when the calcination temperature of the sensitive electrode in the YSZ sensor is 900℃ and the plasma generator is used and not used;

[0063] Figure 6 The response curve of the sensitive electrode of the YSZ sensor to CO with different concentration gradients is shown when the calcination temperature of the sensitive electrode is 800℃ and the plasma generator is not used.

[0064] Figure 7 The response curve of the sensitive electrode of the YSZ sensor to CO with different concentration gradients is shown when the calcination temperature of the sensitive electrode is 900℃ and the plasma generator is not used.

[0065] Figure 8 The response curve of the sensitive electrode of the YSZ sensor to CO with different concentration gradients is shown when the calcination temperature of the sensitive electrode is 1000℃ and the plasma generator is not used.

[0066] Fig. 9 The response curve of the sensitive electrode when the YSZ sensor is used to test the mixed gas of 2-heptanone, n-propanol, n-hexane, ethylbenzene, and CO2 (diluted to 16%) without using a plasma generator;

[0067] Fig.10 The response curve of the sensitive electrode when the YSZ sensor is used to test the mixed gas of propanol, ethanol, butanone, hexanal, CO and ammonia without using a plasma generator;

[0068] Fig.11 The response curve of the sensitive electrode when the plasma generator and YSZ sensor are used to test the mixed gas of CO2 (diluted to 16%), n-propanol, ethylbenzene, 2-heptanone, and n-hexane;

[0069] Fig.12 The response curve of the sensitive electrode when the plasma generator and YSZ sensor are used to test the mixed gas of ethanol, propanol, hexanal, butanone, ammonia, CO, and CO2 (diluted to 16%);

[0070] Figure 1 Middle: 1-input wire; 2-driver; 3-output wire; 4-ionization chamber; 5-test chamber; 6-YSZ sensor; 7-sealing plug; 8-output signal line;

[0071] Figure 2Middle: 9-heating plate, 10-YSZ solid electrolyte layer, 11-reference electrode, 12-sensitive electrode. DETAILED DESCRIPTION

[0072] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. The following embodiments are implemented based on the technical solution of the present invention, and provide detailed implementation methods and specific operation processes, but the protection scope of the present invention is not limited to the following embodiments.

[0073] In the following description, unless otherwise specified, the reagents used are conventional commercially available products, the methods used are common knowledge in the art, and other matters not covered may be solved using existing technologies.

[0074] Principle description of the plasma generator of this scheme:

[0075] 1. Circuit core function: The core of driver 2 is the TL494 chip. As a classic PWM controller, it generates a stable high-frequency pulse signal and controls the output power by adjusting the duty cycle. The feedback loop in the circuit can monitor the current and voltage of the load in real time, send the sampling signal to the error amplifier of the chip, and dynamically adjust the PWM signal after comparing it with the reference voltage, so as to achieve precise control of the load output. At the same time, the circuit also integrates a push-pull inverter, which converts the input DC into a high-frequency AC signal, and further increases the AC voltage amplitude through the subsequent transformer, and finally obtains a high-voltage AC output (peak-to-peak voltage 1kV~7kV), which meets the working requirements of the plasma generator.

[0076] 2. Oscillator part: The TL494 oscillator sets the operating frequency through external resistors and capacitors, and generates a sawtooth wave signal internally as the reference waveform of the PWM comparator. This frequency determines the switching speed of the drive signal, which directly affects the output performance of the push-pull inverter and the discharge effect of the plasma generator. By reasonably designing the oscillation frequency, the circuit can provide a high-frequency signal suitable for the load requirements, laying the foundation for subsequent high-voltage boost and stable operation.

[0077] 3. PWM output and power drive: The PWM comparator inside the TL494 adjusts the duty cycle of the pulse according to the feedback signal of the error amplifier to generate the corresponding PWM drive signal. In the push-pull output mode, the output pins (E1 and E2) of the chip directly drive the gate of the power MOSFET. The MOSFET works in a high-frequency switching state to form a push-pull inverter structure, and generates a high-frequency AC signal at the load end through the switching of high-frequency current. The signal is then further boosted by the transformer to generate a high-voltage AC signal to provide the required operating voltage for the plasma generator.

[0078] 4. Feedback regulation and protection function: This circuit samples the load current through a current detection resistor and sends the sampled signal to the feedback pin of the TL494. When the load current exceeds the preset value, the duty cycle of the PWM signal will be automatically reduced to protect the power devices in the circuit from overcurrent damage. In addition, the feedback design in the circuit can also maintain a stable output of the load to prevent voltage or power fluctuations. This protection mechanism is particularly important and can effectively prevent equipment damage caused by overload during high-voltage and high-frequency operation.

[0079] 5. Applicability and stability: By utilizing the integrated oscillator, error amplifier and push-pull output function of TL494, combined with push-pull inverter and transformer, this circuit not only simplifies the design, but also greatly improves the reliability. It can convert DC power into high-voltage and high-frequency AC signals to provide a stable operating voltage for the plasma generator. At the same time, the dynamic control and protection functions of the output are realized through feedback regulation, which is widely applicable to high-voltage occasions that require precise control of output power.

[0080] Example 1

[0081] like Figure 2 As shown, a YSZ sensor 6 includes a heating plate 9, a YSZ solid electrolyte layer 10, a reference electrode 11 and a sensitive electrode 12. The YSZ solid electrolyte layer 10 and the heating plate 9 are both in the shape of a cuboid, and the length and width of the YSZ solid electrolyte layer 10 are equal to the length and width of the heating plate 9. The lower end surface of the YSZ solid electrolyte layer 10 is fitted with and fixedly connected to the upper end surface of the heating plate 9; the reference electrode 11 and the sensitive electrode 12 are respectively in the shape of cuboids of the same size, and the reference electrode 11 and the sensitive electrode 12 are spaced apart on the upper end surface of the YSZ solid electrolyte layer 10, and the lower end surface of the reference electrode 11 and the lower end surface of the sensitive electrode 12 are respectively fitted with and fixedly connected to the upper end surface of the YSZ solid electrolyte layer 10. The material of the sensitive electrode 12 is Bi2Mn4O 10 The material of the reference electrode 11 is manganese dioxide; a reference electrode lead is provided on the reference electrode 11, and a sensitive electrode lead is provided on the sensitive electrode 12.

[0082] The preparation method of the YSZ sensor 6 specifically includes the following steps:

[0083] (1) Prepare YSZ solid electrolyte layer 10 and heating plate 9 of corresponding size according to design size requirements;

[0084] (2) mixing terpineol and ethyl cellulose in a mass ratio of 94:6 to prepare terpineol slurry;

[0085] (3) mixing manganese dioxide powder and pinene alcohol slurry in a mass ratio of 1:1 in an agate mortar and grinding them evenly to form a first slurry;

[0086] (4) using screen printing technology to print the first slurry at the designed position of the reference electrode 11 on the upper end surface of the YSZ solid electrolyte layer 10 according to the designed size to obtain a prototype of the reference electrode 11;

[0087] (5) placing the product obtained in step (4) in a drying oven, drying at 130° C. for 12 hours, and then placing it in a sintering furnace, sintering at 1400° C. for 2 hours, and then cooling to room temperature to form a reference electrode 11 on the upper end surface of the YSZ solid electrolyte layer 10;

[0088] (6) Bi2Mn4O 10 The mixture is mixed with terpineol slurry in an agate mortar at a mass ratio of 1:1.3 and ground evenly to form a second slurry;

[0089] (7) Printing the second slurry at the designed position of the sensitive electrode 12 on the upper end surface of the YSZ solid electrolyte layer 10 according to the designed size using screen printing technology to obtain a prototype of the sensitive electrode 12;

[0090] (8) placing the product obtained after the treatment in step (7) into a drying oven, setting the temperature condition of the drying oven to 130° C. for drying for 12 hours, and then placing it into a sintering furnace, sintering it at 900° C. for 2 hours, and then cooling it to room temperature to form a sensitive electrode 12 on the upper end surface of the YSZ solid electrolyte layer 10;

[0091] (9) Platinum paste is applied to the surfaces of the reference electrode 11 and the sensitive electrode 12, respectively, and then the reference electrode lead and the sensitive electrode lead are respectively led out through the Pt paste;

[0092] (10) placing the product obtained after the treatment in step (9) in a drying oven at 130° C. for 12 hours, then taking it out and placing it in a sintering furnace at 900° C. for 2 hours to form it, and then taking it out and cooling it to room temperature;

[0093] (11) The heating plate 9 is placed below the YSZ solid electrolyte layer 10 in the product obtained after the treatment in step (10), and the heating plate 9 and the YSZ solid electrolyte layer 10 are glued together using a high-temperature resistant adhesive (such as glass glue), and the YSZ sensor 6 is prepared.

[0094] Example 2

[0095] A YSZ sensor 6, wherein the material of the heating plate 9 is aluminum oxide, the length of the YSZ solid electrolyte layer 10 is l, the width of the YSZ solid electrolyte layer 10 is d, the thickness of the YSZ solid electrolyte layer 10 is h, the length of the heating plate 9 is l, the width of the heating plate 9 is d1, and the thickness of the heating plate 9 is h1, wherein the value range of l is 1.3-1.7 cm, the value range of d is 2-3 cm, the value range of h is 0.5-1 cm, and the value range of h1 is 1.1-1.5 mm, the lengths of the reference electrode 11 and the sensitive electrode 12 are l1 respectively, the widths of the reference electrode 11 and the sensitive electrode 12 are d1, and the thicknesses of the reference electrode 11 and the sensitive electrode 12 are h2, wherein the value range of l1 is 4-6 mm, the value range of d1 is 4-6 mm, and the value range of h2 is 14-16 μm.

[0096] The rest is the same as Example 1.

[0097] Example 3

[0098] After the YSZ sensor 6 was prepared according to the design, its performance was evaluated by constructing a complete CO2 detection device, such as Figure 1 It also provides a basis for actual production applications.

[0099] First, connect the input wire 1 of the plasma generator to an external DC power supply. The other end of the input wire 1 is connected to the driver 2 to convert the DC power into high-voltage AC power. The driver 2 is then led out through the output wire 3. The positive and negative electrodes of the output wire 3 are respectively fixed inside and outside the quartz tube serving as the ionization chamber 4 to form a corona discharge, so that other passing gases are ionized under the action of a strong electric field (interfering gases are ionized to reduce the corresponding gas, and CO2 is ionized to be converted into CO). One end of the quartz tube is connected to the test chamber 5 (a quartz tube cavity) equipped with a YSZ sensor 6 through a rubber tube, and the other end is connected to an external gas pipeline (used to input the gas to be tested / sample gas to the CO2 detection device) through a rubber tube, and a sealing film is wrapped around it to ensure the airtightness of the pipeline. The sample gas is introduced into the CO2 detection device in the form of dynamically prepared gas, and the gas to be tested is Figure 1 The CO2 detection device is introduced at the arrow on the right side of the middle, and enters the test chamber 4 after being ionized by the ionization chamber 4. The CO formed by the ionization conversion undergoes an oxidation-reduction reaction on the YSZ sensor 6.

[0100] In the CO2 detection device, the ionization chamber 4 is a flow device for gas in and out, which is placed on an iron frame. The operating temperature of the YSZ sensor 6 is controlled by a 220V DC regulated power supply, a heating plate 9, and a thermocouple (electrically connected between the power supply and the heating plate 9). The YSZ sensor 6 is covered with a ceramic tube on the outside to protect the rear end of the YSZ sensor 6, and then the ceramic tube and the YSZ sensor 6 are inserted into the interior of the sealing plug 7, and then the sealing plug 7, the ceramic tube and the YSZ sensor 6 are inserted into the whole from one end of the test chamber 5 to complete the installation of the YSZ sensor 6 in the test chamber 5 and the sealing of the test chamber 5. The platinum wire needs to be inserted into the pores of the ceramic tube and the signal output of the YSZ sensor 6 is connected as the output signal line 8, so as to ensure that the signal of the YSZ sensor 6 can be connected to the external acquisition signal source. A sealing plug 7, specifically a rubber plug, is inserted into the ceramic tube, so that after the YSZ sensor 6 is connected to the test chamber 5, the rubber plug is inserted into the gap between the ceramic tube and the quartz tube to ensure that the test gas is in a closed space.

[0101] The testing process is roughly divided into the following steps:

[0102] 1) The prepared YSZ sensor 6 is placed in a quartz tube serving as a test chamber 5 , the test chamber 5 is sealed with a sealing plug 7 , and the airtightness of the test chamber 5 is checked.

[0103] 2) Adjust the DC regulated power supply (connected to the heating plate 9) to provide a certain voltage to the heating plate 9 so that the YSZ sensor 6 can work stably within a certain operating temperature range.

[0104] 3) Adjust the DC regulated power supply (connected to the plasma generator) to provide a certain voltage to the plasma generator so that it is in a suitable working state.

[0105] 4) A certain amount of background gas is introduced into the test chamber 5, and the Agilent 34970A collects signals in real time. When the time-voltage curve is observed to be stable, it is determined that the YSZ sensor 6 has entered a quasi-steady state, and the target test gas (gas to be tested) is introduced. When the introduced target gas makes the signal of the YSZ sensor 6 stable and no longer changes significantly, the test is completed. At this time, the test chamber 5 is replaced with the background gas, and the YSZ sensor 6 is ready for the next measurement after it enters a stable state again.

[0106] Figure 3The response value of the YSZ sensor 6 to the mixed gas of ethanol (1ppm), ethylbenzene (1ppm), 2-heptanone (1ppm), butanone (1ppm), ammonia (1ppm), CO (25ppm), and CO2 (diluted to 16%, volume fraction, the same below) when the calcination temperature of the sensitive electrode 12 in the YSZ sensor 6 is 800°C and the plasma generator is used (corresponding to after ionization) or not used (corresponding to before ionization);

[0107] Figure 4 The response value of the YSZ sensor 6 to the mixed gas of ethanol (1ppm), ethylbenzene (1ppm), 2-heptanone (1ppm), butanone (1ppm), ammonia (1ppm), CO (25ppm), and CO2 (diluted to 16%) when the calcination temperature of the sensitive electrode 12 in the YSZ sensor 6 is 900°C and a plasma generator is used or not used (the working voltage is 8.5V);

[0108] Figure 5 The response value of the YSZ sensor 6 to the mixed gas of ethanol (1ppm), ethylbenzene (1ppm), 2-heptanone (1ppm), butanone (1ppm), ammonia (1ppm), CO (25ppm), and CO2 (diluted to 16%) when the calcination temperature of the sensitive electrode 12 in the YSZ sensor 6 is 1000°C and the plasma generator is used or not;

[0109] Figure 6 It is the response value change curve of YSZ sensor 6 when the calcination temperature of sensitive electrode 12 in YSZ sensor 6 is 800°C and no plasma generator is used, and the YSZ sensor 6 is tested (working voltage is 8.5V) for CO under different concentration gradients (25ppm, 45ppm, 65ppm, 85ppm, 105ppm, 125ppm, 145ppm, 165ppm).

[0110] Figure 7 The response value change curve of the YSZ sensor 6 under different concentration gradients of CO (25ppm, 45ppm, 65ppm, 85ppm, 105ppm, 125ppm, 145ppm, 165ppm) is shown when the calcination temperature of the sensitive electrode 12 in the YSZ sensor 6 is 900°C and no plasma generator is used (when the operating voltage is 8.5V).

[0111] Figure 8The response value change curve of the YSZ sensor 6 under different concentration gradients of CO (25ppm, 45ppm, 65ppm, 85ppm, 105ppm, 125ppm, 145ppm, 165ppm) is shown when the calcination temperature of the sensitive electrode 12 in the YSZ sensor 6 is 1000°C and no plasma generator is used (when the operating voltage is 8.5V).

[0112] Figures 3 to 5 The response test results (response value changes) of the YSZ sensor 6 of the present invention to mixed gases at different calcination temperatures (800°C, 900°C and 1000°C) with and without a plasma generator are shown. The test gases include ethanol (1ppm), ethylbenzene (1ppm), 2-heptanone (1ppm), butanone (1ppm), ammonia (1ppm), CO (25ppm) and CO2 (diluted to 16%), and the operating voltage is 8.5V.

[0113] Figures 6 to 8 The response test results (response value change curve) of the YSZ sensor 6 of the present invention to different concentration gradients of CO gas at different calcination temperatures (800°C, 900°C and 1000°C) are shown. The test concentrations include (25ppm, 45ppm, 65ppm, 85ppm, 105ppm, 125ppm, 145ppm, 165ppm), and the working voltage is 8.5V.

[0114] By analyzing Figures 3 to 5 According to the test data, the YSZ sensor 6 exhibits excellent CO2 selective detection capability:

[0115] Among all the test gases, CO2 (16%) produced the strongest response signal: the response value of the sample calcined at 800°C increased from 7.34mV to 35.29mV, an increase of 27.95mV; the response value of the sample calcined at 900°C increased from 8.19mV to 32.97mV, an increase of 24.78mV; the response value of the sample calcined at 1000°C increased from 11.14mV to 37.54mV, an increase of 26.4mV. In contrast, the response values ​​of VOCs gases (such as ethylbenzene, n-propanol, heptanone, etc.) generally decreased to below 5mV after ionization. Even if the CO concentration increased to 50ppm, its highest response value (10.89mV) was still much lower than CO2, indicating that the YSZ sensor 6 has good anti-interference performance.

[0116] Through Figures 3 to 5 as well as Figures 6 to 8 By analyzing the test data, it can be determined that 900°C is the optimal calcination temperature of the sensitive electrode 12 in the YSZ sensor 6:

[0117] First, in terms of response amplitude, the sample calcined at 900°C showed a response amplitude of 35mV, which was more stable and consistent than the samples calcined at 800°C and 1000°C, showing a high sensitivity to changes in CO2 concentration. Second, the sample calcined at 900°C performed best in sensitivity and resolution, with a high degree of separation in the response curve, which could clearly distinguish different concentrations of CO2, ensuring the accuracy and reliability of the detection.

[0118] In terms of linearity, the response of the sample calcined at 900 °C showed a good linear relationship with the CO2 concentration, which simplified the calibration process of the YSZ sensor 6 and improved the measurement accuracy. In contrast, the linearity of the samples calcined at 800 °C and 1000 °C was poor, limiting their application in quantitative analysis.

[0119] In terms of stability and noise level, the baseline of the 900℃ sample is stable and the noise level is low, ensuring the consistency and reliability of the measurement results, while the 800℃ and 1000℃ samples have baseline fluctuations and noise problems.

[0120] In addition, the sample calcined at 900°C has the widest dynamic range, which can effectively cover the main concentration range of CO2 in human exhaled breath and meet the diverse needs in practical applications.

[0121] In terms of response speed and recovery characteristics, the 900°C sample exhibited rapid response and good recovery ability, which is suitable for real-time monitoring and ensures the excellent performance of the sensor in a dynamic environment.

[0122] In terms of operating voltage, the 900°C sample can achieve optimal performance at 8.5V, which simplifies equipment design and improves practicality.

[0123] Microstructure optimization is an important reason for the excellent performance of YSZ sensor 6 at 900℃ calcination temperature. 10 The crystal structure and pore distribution of the material are in an optimal state, providing more specific adsorption sites and active reaction areas for CO molecules, while effectively suppressing the response of interfering gases such as VOCs, and improving the selectivity and sensitivity of the YSZ sensor 6. In addition, 900°C as an intermediate temperature fully activates the material of the sensitive electrode 12, while avoiding the problem of excessively dense material structure or phase change caused by excessively high temperature, ensuring the consistency and controllability of the YSZ sensor 6 in mass production.

[0124] In summary, the YSZ sensor 6 calcined at 900°C exhibited the best performance in multiple key performance indicators, including response amplitude, sensitivity, linearity, stability, dynamic range, response speed, and microstructure. This temperature condition not only optimizes the physical and chemical properties of the sensitive material, but also ensures the high selectivity and high reliability of the YSZ sensor 6 in practical applications.

[0125] Fig. 9 The response curve of the sensitive electrode 12 of the YSZ sensor 6 when the calcination temperature is 900°C and the plasma generator is not used, and the mixed gas of 2-heptanone (1ppm), n-propanol (1ppm), n-hexane (1ppm), ethylbenzene (1ppm), and CO2 (diluted to 16%) is tested (the working voltage is 8.5V);

[0126] Fig.10 The response curve of the sensitive electrode 12 of the YSZ sensor 6 when the calcination temperature is 900°C and the plasma generator is not used, and the mixed gas of propanol (1ppm), ethanol (1ppm), butanone (1ppm), hexanal (500ppb), CO (25ppm), CO (50ppm), and ammonia (1ppm) is tested (the working voltage is 8.5V);

[0127] Fig.11 The response curve of the sensitive electrode 12 of the YSZ sensor 6 when the calcination temperature is 900°C and a plasma generator is used to test a mixed gas of CO2 (diluted to 16%), n-propanol (1ppm), ethylbenzene (1ppm), 2-heptanone (1ppm), and n-hexane (1ppm) (operating voltage is 8.5V);

[0128] Fig.12 The response curve of the sensitive electrode 12 of the YSZ sensor 6 when the calcination temperature is 900°C and the plasma generator is used to test the mixed gas of ethanol (1ppm), propanol (1ppm), hexanal (1ppm), butanone (1ppm), ammonia (1ppm), CO (25ppm), CO (50ppm), and CO2 (diluted to 16%) (the working voltage is 8.5V);

[0129] from Figures 9 to 12 It can be clearly observed that the response of other interfering volatile organic compounds (VOCs) gases is significantly reduced before and after the plasma generator is activated, while for the 16% concentration of CO2 gas, the YSZ sensor 6 produces the most significant response signal. Fig.11 In the experiment, the response amplitude of CO2 is about 60mV (from -40mV to -100mV), while in Fig.12The response amplitude of CO2 is stable between 30 and 40 mV. This significant change in the response intensity amplitude shows that the device has excellent detection sensitivity for CO2.

[0130] During the experiment, a variety of potential interfering gases were tested, including 1ppm n-butanol, 1ppm ethanol, 1ppm ethylbenzene, 25ppm and 50ppm carbon monoxide (CO), 500ppb hexanal, and 1ppm ammonia. Although these interfering gases can produce responses, their response signals are significantly weaker than CO2. Fig.12 Even if the CO concentration is increased to 50 ppm, the response amplitude is still much lower than that of 16% CO2, which fully proves the excellent performance of the device of the present invention in selective detection.

[0131] In addition, it can be observed from the response curve that repeated tests on CO2 showed stable and consistent response characteristics, the response curves were similar in shape, and the amplitude fluctuations were small, indicating that the device has good repeatability and stability.

[0132] Further analysis of the shape of the response curve shows that the YSZ sensor 6 exhibits a fast response speed and good baseline recovery ability for both CO2 and other gases. By comparing the experimental results, it can be found that the use of the plasma generator significantly improves the sensor's response selectivity to CO2. This finding verifies the innovation and effectiveness of the present invention's combination of the YSZ sensor 6 and the plasma generator.

[0133] In addition, the device of the present invention has a simple structure, convenient operation, uses low-cost materials and manufacturing processes, is suitable for large-scale production and portable applications, and meets the diverse needs of personal health monitoring and medical diagnosis. With the assistance of plasma technology, the YSZ sensor 6 not only improves the accuracy and reliability of CO2 detection, but also expands its application prospects in environmental monitoring, industrial emission control, and intelligent health management.

[0134] The present invention provides an efficient, reliable and widely applicable CO2 detection solution, which successfully overcomes the limitations of traditional YSZ sensors in terms of high selectivity and rapid response, has significant technical advantages and market competitiveness, and opens up a new path for the development and application of CO2 detection technology.

[0135] In summary, with the growing demand for environmental monitoring, personal health management and medical diagnosis, it is particularly important to develop a highly selective, highly sensitive and simple CO2 detection device. The present invention innovatively realizes highly selective detection of CO2 in human exhaled breath by combining plasma technology with YSZ solid electrolyte sensor, which has broad application prospects and significant practical value.

[0136] The above description of the embodiments is to facilitate the understanding and use of the invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.

Claims

1. A CO2 detection device based on a YSZ sensor and a plasma generator, characterized in that: It includes a plasma generator, a test chamber (5) and a YSZ sensor (6); The YSZ sensor (6) is arranged inside the test chamber (5); The YSZ sensor (6) comprises a YSZ solid electrolyte layer (10), a reference electrode (11) and a sensitive electrode (12); the reference electrode (11) and the sensitive electrode (12) are arranged on the surface of the YSZ solid electrolyte layer (10) at intervals, and the material of the sensitive electrode (12) is Bi2Mn4O 10 ; The plasma generator is connected to the gas inlet end of the test chamber (5) and is used to ionize the gas to be tested.

2. A CO2 detection device based on a YSZ sensor and a plasma generator according to claim 1, characterized in that: The YSZ sensor (6) further comprises a heating plate (9); the reference electrode (11) and the sensitive electrode (12) are arranged on a first surface of the YSZ solid electrolyte layer (10), and the heating plate (9) is arranged on a second surface of the YSZ solid electrolyte layer (10), and the first surface and the second surface are a pair of opposite surfaces of the YSZ solid electrolyte layer (10).

3. A CO2 detection device based on a YSZ sensor and a plasma generator according to claim 2, characterized in that: The YSZ sensor (6) is prepared by the following steps: S1: printing a slurry containing a reference electrode material on a first surface of a YSZ solid electrolyte layer (10) by screen printing, drying and sintering to form a reference electrode (11); S2: printing a slurry containing a sensitive electrode material on a first surface of the YSZ solid electrolyte layer (10) by screen printing, arranging it at intervals from a reference electrode (11), drying and sintering to form a sensitive electrode (12); S3: applying platinum slurry on the surface of the reference electrode (11) and the sensitive electrode (12), and drawing electrode leads from the platinum slurry respectively, and sintering them into shape after drying; S4: bonding the heating sheet (9) to the second surface of the YSZ solid electrolyte layer (10).

4. A CO2 detection device based on a YSZ sensor and a plasma generator according to claim 3, characterized in that: In step S1, the slurry containing the reference electrode material is prepared by mixing the reference electrode material with pinene alcohol slurry and grinding them uniformly; in step S2, the slurry containing the sensitive electrode material is prepared by mixing the sensitive electrode material with pinene alcohol slurry and grinding them uniformly; The terpineol slurry is formed by mixing terpineol and ethyl cellulose.

5. A CO2 detection device based on a YSZ sensor and a plasma generator according to claim 3, characterized in that: In step S3, the sintering temperature is 700-1100°C.

6. A CO2 detection device based on a YSZ sensor and a plasma generator according to claim 1, characterized in that: The material of the reference electrode (11) is manganese dioxide.

7. A CO2 detection device based on a YSZ sensor and a plasma generator according to claim 1, characterized in that: The plasma generator comprises an input wire (1), a driver (2), an output wire (3) and an ionization chamber (4); One end of the input wire (1) is connected to a DC power supply, and the other end of the input wire (1) is connected to a driver (2); The driver (2) is used to convert the direct current input by the input wire (1) into high-voltage alternating current and output it through the output wire (3); One end of the output wire (3) is connected to the driver (2), and the positive electrode and the negative electrode of the other end of the output wire (3) are respectively connected to the inside and the outside of the ionization chamber (4), so as to form a corona discharge; One end of the ionization chamber (4) is an air inlet end for introducing the gas to be tested; the other end of the ionization chamber (4) is connected to the air inlet end of the test chamber (5) for sending the ionized gas to be tested into the test chamber (5).

8. A CO2 detection device based on a YSZ sensor and a plasma generator according to claim 7, characterized in that: The driver (2) comprises a push-pull inverter and a transformer connected to each other; the push-pull inverter is used to convert the input direct current into alternating current, and the transformer is used to increase the voltage amplitude of the alternating current to form high-voltage alternating current; The ionization chamber (4) is a quartz tube.

9. A CO2 detection device based on a YSZ sensor and a plasma generator according to claim 7, characterized in that: The test chamber (5) is a quartz tube; The YSZ sensor (6) is mounted on a sealing plug (7), and the sealing plug (7) is installed at one end of the test chamber (5) so that the YSZ sensor (6) extends into the interior of the test chamber (5); the YSZ sensor (6) is also connected to an output signal line (8), and the output signal line (8) is led out from the test chamber (5) through the sealing plug (7); The other end of the test chamber (5) is connected to a plasma generator.

10. A CO2 detection system, characterized in that: The CO2 detection device based on the YSZ sensor and the plasma generator as described in any one of claims 1 to 9 is used to detect the change of CO2 concentration in the airflow.

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