Gas concentration detection method, target concentration gas generation method, and target concentration gas generation device

Abstract

The invention provides a gas concentration detection method and a target concentration gas generation method and device, the method is carried out through a gas concentration detection device, and the gas concentration detection device comprises a gas channel, and a first detection device and a second detection device which are connected with the gas channel; the method comprises the following steps: independently carrying out measurement through a first detection device, and obtaining a first response current of to-be-detected gas measured by the first detection device; jointly measuring through the first detection device and the second detection device to obtain a second response current of the to-be-detected gas measured by the first detection device; and determining the concentration of the gas to be detected according to the gas diffusion impedance of the gas concentration detection device calibrated in advance, the first response current and the second response current. According to the invention, the gas diffusion impedance only needs to be calibrated once in advance, the gas concentration is determined by combining the response current of the double detection devices, and the stability and the measurement accuracy of the detection device can be improved.

Description

Technical Field

[0001] The present application relates to the field of chemical technology, and in particular to a gas concentration detection method, a method and a device for generating gas of a target concentration. Background Art

[0002] The response characteristics of conventional electrochemical gas sensors are relatively complex, and the impact of the environment and the electrode's own activity state on the response value becomes greater, which in turn affects the stability and reliability of the sensor measurement. The current method to improve the accuracy and reliability of sensor measurements is to calibrate the sensor using a standard gas of known concentration under conditions as close to the operating environment as possible. Using a standard gas generator to generate a standard gas of known concentration, the sensitivity of the sensor can be calibrated at the application site, improving the convenience of its application.

[0003] The standard gas generator uses diffusion tubes and permeation tubes to generate target gas. When the permeation tube and diffusion tube are placed in the constant temperature chamber of the generator, at a certain temperature, the amount of substance that permeates outward from the permeation tube wall or evaporates outward from the diffusion tube per unit time is a fixed constant. Therefore, you only need to adjust the flow rate of the added dilution gas to obtain a standard gas with a lower concentration of any set stable flow rate. The concentration of the generated gas is determined by weighing. The diffusion rate / permeability can be calculated by weighing the weight loss of the permeation tube (diffusion tube) at a certain time interval, and the concentration of the target substance in the output gas can be determined by combining the flow rate of the dilution gas, which is not convenient in application.

[0004] In addition, the above method is only applicable to pure material standard sources. For most gaseous substances at normal temperature and pressure, such as HCL, HF, NO2, etc., it is impossible to use the diffusion tube method to generate calibration gas. At the same time, it is also difficult to make a permeation tube with pure standard substances. For such compounds, we can only use a mixture with a certain content as a standard source, so the weight loss method cannot be used to determine the concentration of the gas. Moreover, after a period of permeation / diffusion, the concentration of the standard substance in the mixture also changes, which will cause the weight loss rate / diffusion rate to change, thereby causing the concentration of the output standard gas to change. Therefore, a highly stable measurement method is needed to determine the gas concentration generated by the gas generator. Summary of the invention

[0005] The purpose of this application is to provide a gas concentration detection method, a method and device for generating gas of target concentration, which can accurately measure the concentration of the gas to be measured when the sensitivity of the electrochemical gas sensor drifts, and apply it to determine the standard gas concentration generated by the gas generator, reduce the design difficulty of the standard gas generator, and expand its application range. In addition, the sensor structure design principles and measurement methods provided by this solution can also be directly used in intelligent sensor design to improve the stability and accuracy of measurement.

[0006] The present application provides a gas concentration detection method, which is performed by a gas concentration detection device, the gas concentration detection device comprising a gas channel and a first detection device and a second detection device connected to the gas channel; the method comprises:

[0007] Performing measurement using the first detection device alone to obtain a first response current of the gas to be measured measured by the first detection device;

[0008] The first detection device and the second detection device are used to perform measurement together to obtain a second response current of the gas to be measured measured by the first detection device;

[0009] The concentration of the gas to be measured is determined according to the gas diffusion impedance of the gas concentration detection device calibrated in advance, as well as the first response current and the second response current.

[0010] In one embodiment, before determining the concentration of the gas to be measured based on the gas diffusion impedance of the gas concentration detection device calibrated in advance, and the first response current and the second response current, the method further includes:

[0011] Detecting and obtaining a first sample response current of a sample gas of known concentration by a first detection device;

[0012] By means of the first detection device and the second detection device, a second sample response current and a third sample response current of the sample gas are detected;

[0013] The gas diffusion impedance of the gas concentration detection device is determined according to the known concentration, the first sample response current, the second sample response current and the third sample response current.

[0014] In one embodiment, the gas diffusion impedance of the gas concentration detection device is determined according to the known concentration, the first sample response current, the second sample response current and the third sample response current, using the following formula:

[0015]

[0016] Among them, R g is the gas diffusion impedance, C1 is the known gas concentration, I1 is the first sample response current, I2 is the second sample response current, and I3 is the third sample response current.

[0017] In one embodiment, before determining the concentration of the gas to be measured based on the gas diffusion impedance of the gas concentration detection device calibrated in advance, and the first response current and the second response current, the method further includes:

[0018] Controlling the first detection device and the second detection device to be at an initial potential, and detecting and obtaining a first sample initial current and a second sample initial current of the sample gas through the first detection device;

[0019] Controlling the first detection device to be at a working potential, and detecting and obtaining a first sample working current of the sample gas through the first detection device;

[0020] Controlling the first detection device and the second detection device to be at a working potential, and detecting and obtaining a second sample working current and a third sample working current of the sample gas through the first detection device;

[0021] The gas diffusion impedance of the gas concentration detection device is determined according to the known concentration, the first sample initial current, the second sample initial current, the first sample operating current, the second sample operating current and the third sample operating current.

[0022] In one embodiment, before controlling the first detection device and the second detection device to be at an initial potential and detecting and obtaining the first sample initial current and the second sample initial current of the sample gas through the first detection device, the method further includes:

[0023] The first detection device and the second detection device are controlled to be at a cleaning potential to clean impurities in the first detection device and the second detection device.

[0024] In one embodiment, the gas diffusion impedance of the gas concentration detection device is determined according to the known concentration, the first sample initial current, the second sample initial current, the first sample working current, the second sample working current and the third sample working current, using the following formula:

[0025]

[0026] Among them, R g is the gas diffusion impedance, C1 is the known gas concentration, I 10 is the initial current of the first sample, I 20 is the initial current of the second sample, I 1a is the first sample operating current, I 2b is the second sample operating current, I 1b This is the third sample operating current.

[0027] In one embodiment, the concentration of the gas to be measured is determined based on the gas diffusion impedance of the gas concentration detection device calibrated in advance, as well as the first response current and the second response current, and is calculated using the following formula:

[0028]

[0029] Among them, R g is the gas diffusion impedance, C is the concentration of the gas to be measured, I 210a is the first response current, I 210c is the second response current.

[0030] In one embodiment, when the first detection device and the second detection device are used to perform the measurement together, the method further includes: obtaining a third response current of the gas to be measured measured by the second detection device;

[0031] The concentration of the gas to be measured is determined according to the gas diffusion impedance of the gas concentration detection device calibrated in advance, as well as the first response current and the second response current, including:

[0032] The concentration of the gas to be measured is determined according to the gas diffusion impedance of the gas concentration detection device calibrated in advance, as well as the first response current, the second response current and the third response current.

[0033] In one embodiment, the concentration of the gas to be measured is determined according to the gas diffusion impedance of the gas concentration detection device calibrated in advance, as well as the first response current, the second response current and the third response current, including:

[0034]

[0035] Among them, R g is the gas diffusion impedance, C is the concentration of the gas to be measured, I 210a is the first response current, I 210c is the second response current, I 220c is the third response current.

[0036] The present application also provides a method for generating a gas of a target concentration, which is performed by a standard gas generating device, the standard gas generating device comprising a gas distribution module, a gas source module connected to the gas distribution module, a transmission channel connected to the gas source module, a gas concentration detection device connected to the transmission channel, the gas concentration detection device comprising a gas channel and a first detection device and a second detection device connected to the gas channel; the gas channel is connected to the transmission channel; the method comprises:

[0037] The gas distribution module is controlled to generate a predetermined flow of clean gas to enter the gas source module, and the gas source module is controlled to generate a target gas. The clean gas and the target gas are mixed to form a gas to be tested;

[0038] Detecting the concentration of the gas to be tested by any of the above methods;

[0039] When the concentration of the gas to be measured is different from the target concentration, the predetermined flow rate of the clean gas and the speed of the target gas generated by the gas source module are adjusted to adjust the concentration of the gas to be measured to the target concentration.

[0040] The present application also provides a target concentration gas generation device, comprising:

[0041] A gas distribution module, used to generate a predetermined flow of clean gas to enter the gas source module;

[0042] A gas source module, connected to a gas distribution module, for generating a target gas;

[0043] A transmission channel, connected to the gas source module, for transmitting target gas and clean gas;

[0044] A gas concentration detection device, the gas concentration detection device comprising a gas channel and a first detection device and a second detection device connected to the gas channel; the gas channel is connected to the transmission channel;

[0045] The intelligent control module is connected to the gas distribution module, the gas source module and the gas concentration detection device, and the intelligent control module is used to execute the above method.

[0046] In one embodiment, the gas channel of the gas concentration detection device includes:

[0047] A first diffusion channel;

[0048] The gas concentration detection device also includes:

[0049] The first buffer chamber has one end connected to the first diffusion channel and the other end connected to the first detection device and the second detection device respectively.

[0050] In one embodiment, the gas concentration detection device further includes:

[0051] a first reference electrode;

[0052] a first pair of electrodes;

[0053] An electrolyte, one end of the electrolyte is connected to the first detection device and the second detection device respectively, and the other end of the electrolyte is connected to the first reference electrode and the first pair of electrodes respectively.

[0054] In one embodiment, the gas concentration detection device further includes:

[0055] The electrode support membrane has one end connected to the first buffer chamber and the other end connected to the first detection device and the second detection device respectively.

[0056] In one embodiment, the gas concentration detection device further includes:

[0057] A third detection device, one end of which is connected to one end of the electrolyte and is used to monitor changes in gas concentration;

[0058] The gas channel also includes:

[0059] a second buffer chamber, the second buffer chamber being connected to a third detection device;

[0060] The second diffusion channel is connected to the second buffer chamber.

[0061] In one embodiment, the gas concentration detection device further includes:

[0062] A gas concentration change monitoring module is connected to the transmission channel and is used to monitor gas concentration changes.

[0063] In one embodiment, the gas concentration detection device further includes:

[0064] Electrolytes;

[0065] A second counter electrode and a second reference electrode, wherein the second counter electrode and the second reference electrode are separated from the first detection device and the second detection device by an electrolyte;

[0066] The inert substrate is connected to one end of the electrolyte and is used to improve the stability of the gas concentration detection device.

[0067] In one embodiment, the gas concentration detection device further includes:

[0068] A heating substrate is connected to the inert substrate and is used for performing constant temperature control on the gas concentration detection device.

[0069] The beneficial effects of this application compared with the prior art are:

[0070] The method of the present invention combines the response current of the dual detection device to determine the gas concentration. The measurement of the gas concentration is not affected by the change of the sensor sensitivity, which improves the accuracy and reliability of the measurement and realizes stable measurement of the concentration of the gas to be measured. BRIEF DESCRIPTION OF THE DRAWINGS

[0071] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0072] Figure 1 is a schematic diagram of a gas generating device provided in one embodiment of the present application;

[0073] Figure 2 is a structural schematic diagram of a gas concentration detection device provided in another embodiment of the present application;

[0074] Figure 3 is a structural schematic diagram of a gas concentration detection device provided by another embodiment of the present application;

[0075] Figure 4 is a schematic diagram of a miniaturized structure of a gas concentration detection device provided in yet another embodiment of the present application;

[0076] Figure 5 This application Figure 4 Schematic diagram of another scheme of miniaturized structure of gas concentration detection device;

[0077] Figure 6 A schematic diagram of a method for generating a gas of a target concentration provided in one embodiment of the present application;

[0078] Figure 7 is a first equivalent circuit diagram of a gas concentration detection device provided in one embodiment of the present application;

[0079] Figure 8 is a second equivalent circuit schematic diagram provided by an embodiment of the present application;

[0080] Fig. 9 It is a flow chart of a gas concentration detection method provided in one embodiment of the present application;

[0081] Fig.10 is a schematic diagram of a first solution for calibrating gas diffusion impedance provided by an embodiment of the present application;

[0082] Fig.11 It is a schematic diagram of a second scheme for calibrating gas diffusion impedance provided by an embodiment of the present application;

[0083] Fig.12 This is provided by an embodiment of the present application Fig.11 Schematic diagram corresponding to the current potential scheme 1;

[0084] Fig.13 This is provided by an embodiment of the present application Fig.11 Schematic diagram corresponding to current potential scheme 2.

[0085] The above drawings include the following reference numerals:

[0086] 1-gas generating device; 110-gas distribution module; 120-gas source module; 200-gas concentration detecting device; 210-first detecting device; 220-second detecting device; 230-gas channel; 231-first diffusion channel; 232-first buffer chamber; 233-second diffusion channel; 234-second buffer chamber; 240-third detecting device; 250-electrolyte; 261-first reference electrode; 262-first pair of electrodes; 251-electrolyte; 263-second pair of electrodes; 264-second reference electrode; 270-housing; 280-dustproof film; 290-electrode supporting film; 300-gas concentration change monitoring module; 400-intelligent control module; 500-transmission channel; 600-heating substrate; 700-inert substrate. DETAILED DESCRIPTION

[0087] The terms “first”, “second”, “third”, etc. are only used for distinguishing descriptions and do not indicate the order of arrangement, nor can they be understood as indicating or implying relative importance.

[0088] In addition, the terms "horizontal", "vertical", "overhanging" and the like do not mean that the components are required to be absolutely horizontal or overhanging, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0089] In the description of the present application, it should be noted that the terms "inside", "outside", "left", "right", "up", "down", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, or are directions or positional relationships in which the products of the present application are usually placed when in use. They are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present application.

[0090] In the description of this application, unless otherwise clearly specified and limited, the terms "set", "installed", "connected" and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the internal connection of two elements.

[0091] The embodiment of the present application provides a gas generation device with a target concentration. Figure 1 Schematic diagram of a gas generating device provided in one embodiment of the present application. Figure 1 As shown, the gas generating device 1 includes: a gas distribution module 110 , a gas source module 120 , a transmission channel 500 , a gas concentration detection device 200 and an intelligent control module 400 .

[0092] Among them, the gas distribution module 110 includes an air purification device, etc., which is used to generate clean gas with a controllable flow rate. The gas source module 120 includes a gas generating material (such as a permeation tube, a diffusion tube, a target gas adsorption slow-release material, a pure chemical liquid with a suitable vapor pressure, a solid material, a mixture, a speed-controllable chemical reaction chamber, etc.) for generating the target gas. The transmission channel 500 is connected to the gas source module 120 and is used to transmit the gas to be tested formed by a mixture of the target gas and the clean gas. The gas concentration detection device 200 is used to accurately and reliably measure the concentration of the gas to be tested in the transmission channel 500. The gas concentration detection device 200 includes a gas channel 230 and a first detection device 210 and a second detection device 220 connected to the gas channel 230; the gas channel 230 is connected to the transmission channel 500. The intelligent control module 400 is connected to the gas distribution module 110, the gas source module 120 and the gas concentration detection device 200, and is used to adjust the predetermined flow rate of the clean gas and the speed of the target gas generated by the gas source module according to the concentration of the gas to be tested detected by the gas concentration detection device 200, so as to adjust the concentration of the gas to be tested to the target concentration.

[0093] In one embodiment, the gas generating device 1 also includes: a gas concentration change monitoring module 300, the gas concentration change monitoring module 300 is connected to the transmission channel 500, and is used to monitor the gas concentration change. Among them, the gas concentration change monitoring module 300 includes a sensor that can continuously monitor the concentration of the gas to be measured in the transmission channel 500, which can be an electrochemical sensor, an infrared sensor, a PID (Photoionization Detector), a MOS (Metal Oxide Semiconductor), etc.

[0094] It should be noted that the gas concentration detection device 200 can have various structures. Figure 1 In the illustrated embodiment, the first detection device 210 and the second detection device 220 may be electrochemical gas sensors. The gas channel 230 may include a first diffusion channel 231 and a first buffer chamber 232 .

[0095] Figure 2 is a schematic diagram of the structure of a gas concentration detection device provided by another embodiment of the present application. Figure 1-2 As shown, the gas channel 230 of the gas concentration detection device 200 includes: a first diffusion channel 231 and a first buffer chamber 232, the first diffusion channel 231 is used to control the speed at which the gas to be detected enters the first detection device 210 and the second detection device 220; one side of the first buffer chamber 232 is connected to the first diffusion channel 231, and the other side is respectively connected to the first detection device 210 and the second detection device 220, which is used to reduce the concentration difference caused by the excessive diffusion of the gas in the first diffusion channel 231.

[0096] exist Figure 2 In the illustrated embodiment, the gas concentration detection device 200 also includes: a first reference electrode 261, a first pair of electrodes 262, and an electrolyte 250; the first reference electrode 261 is used to provide a reference potential for the first detection device 210 and the second detection device 220; the first pair of electrodes 262 is used to ensure that current flows through the electrolyte 250; one side surface of the electrolyte 250 is respectively connected to the first detection device 210 and the second detection device 220, and the other side surface is connected to the first reference electrode 261 and the first pair of electrodes 262.

[0097] like Figure 2 As shown, the gas concentration detection device 200 also includes: a shell 270 and a dust-proof film 280. The shell 270 is arranged on the outside of the first detection device 210, the second detection device 220, the first buffer chamber 232, the first diffusion channel 231, the first reference electrode 261, the first pair of electrodes 262 and the electrolyte 250. The dust-proof film 280 is arranged on the surface of the shell 270, covering the first diffusion channel 231, and is used to prevent dust and the like from entering the gas concentration detection device 200.

[0098] like Figure 2 As shown, the gas concentration detection device 200 also includes: an electrode support membrane 290, one side of the electrode support membrane 290 is connected to the first buffer chamber 232, and the other side is connected to the first detection device 210 and the second detection device 220 respectively, which is used to ensure that the first detection device 210 and the second detection device 220 maintain their shape and position unchanged during operation, and maintain the long-term stability and reliability of the gas concentration detection device 200.

[0099] Figure 3 is a structural schematic diagram of a gas concentration detection device provided by another embodiment of the present application, such as Figure 1-3 As shown, the gas concentration detection device 200 also includes: a third detection device 240; the gas channel 230 also includes: a second buffer chamber 234, a second diffusion channel 233; wherein the second buffer chamber 234 is connected to the third detection device 240; the second diffusion channel 233 is connected to the second buffer chamber 234; one end of the third detection device 240 is connected to one end of the electrolyte 250 for monitoring changes in gas concentration.

[0100] Among them, the third detection device 240 is in the same electrolyte 250 environment as the first detection device 210 and the second detection device 220, and shares the first pair of electrodes 262 and the first reference electrode 261 with them. The third detection device 240 is individually connected to the second diffusion channel 233 and the second buffer chamber 234, and its response to the gas is not affected by the first detection device 210 and the second detection device 220.

[0101] Among them, when the first detection device 210 and the second detection device 220 are used to monitor the change of gas concentration, since the first detection device 210 and the second detection device 220 need to measure the gas concentration in a steady state, continuous monitoring cannot be achieved. For occasions where continuous monitoring is required, the third detection device 240 can be used to continuously monitor the gas concentration. This design facilitates the integration and miniaturization of the gas concentration detection device 200, and can also achieve self-calibration of the gas concentration detection device 200.

[0102] Among them, self-calibration means that when the target gas concentration in the transmission channel 500 remains stable for a relatively short time (but its exact concentration is unknown), and it is suspected that the performance of the third detection device 240 has decayed or needs maintenance, the sensitivity of the third detection device 240 is calibrated to improve the stability and reliability of the measurement of the gas concentration detection device 200.

[0103] In one embodiment, Figure 4 FIG. 1 is a schematic diagram of a miniaturized structure of a gas concentration detection device provided in another embodiment of the present application. Figure 4 As shown, the gas concentration detection device further includes: an electrolyte 251, an inert substrate 700 and a heating substrate 600. The first detection device 210 and the second detection device 220 are micro-electrodes; the first detection device 210, the second detection device 220, the second pair of electrodes 263 and the second reference electrode 264 are arranged in intervals in the electrolyte 251; the electrolyte 251 can be a liquid including an electrolyte, a conductive polymer, a colloidal electrolyte or a high-temperature solid electrolyte, etc.; the inert substrate 700 is closely connected with the electrolyte 251, the first detection device 210, the second detection device 220, the second pair of electrodes 263 and the second reference electrode 264 to improve the stability of the gas concentration detection device; the heating substrate 600 is connected with the inert substrate 700 to perform constant temperature control on the gas concentration detection device. Among them, the first detection device 210 and the second detection device 220 are high line-to-surface ratio structures (such as interdigitated, spiral or other alternating lattice structures), and the first detection device 210 and the second detection device 220 are intertwined on the plane but maintain a preset distance; wherein, the preset distance between the first detection device 210 and the second detection device 220 can be 20-500μm; the line-to-surface ratio refers to the ratio of the length of the first detection device 210 or the second detection device 220 to the surface area of ​​the first detection device 210 or the second detection device 220; the length of the first detection device 210 and the second detection device 220 is preferably between millimeters and tens of centimeters.

[0104] Furthermore, when the electrolyte 251 is liquid, the gas concentration detection device further includes a sealing component (not shown in the figure), which is used to accommodate the electrolyte 251.

[0105] In another embodiment, Figure 5 This application Figure 4 Another schematic diagram of the miniaturized structure of the gas concentration detection device is shown in FIG. Figure 5 As shown, the first buffer chamber 264 can be a gas permeable membrane, which includes but is not limited to a porous diffusion membrane or a permeable membrane, etc. The gas permeable membrane is located on the surface of the electrolyte 251, and the gas passes through the gas permeable membrane to reach the first detection device 210 and the second detection device 220. The first detection device 210, the second detection device 220, the second pair of electrodes 263 and the second reference electrode 264 are arranged in the electrolyte 251 at intervals and in close contact with the gas permeable membrane, and the mass transfer channels through which the gas passes through the gas permeable membrane to reach the first detection device 210 and the second detection device 220 partially overlap. Among them, the electrolyte 251 is a thin layer electrolyte; the first detection device 210, the second detection device 220, the second pair of electrodes 263 and the second reference electrode 264 are prepared on the gas permeable membrane, such as by screen printing, inkjet printing or MEMS (Micro-Electro-Mechanical Systems) processing technology; the inert substrate 700 is closely connected to the electrolyte 251.

[0106] In addition, an embodiment of the present application also provides a method for generating gas of a target concentration, which can be performed by the gas generating device 1 described in the above embodiment. Figure 6 A schematic diagram of a method for generating a gas having a target concentration provided in an embodiment of the present invention is shown in FIG. Figure 6 As shown, the method for generating the target concentration of gas may include the following steps:

[0107] Step S410: Control the gas distribution module 110 to generate a predetermined flow of clean gas to enter the gas source module 120, and control the gas source module 120 to generate a target gas, and the clean gas and the target gas are mixed into a gas to be tested.

[0108] Step S420: Detecting the concentration of the gas to be detected by the gas concentration detection device 200.

[0109] Step S430: When the concentration of the gas to be measured is different from the target concentration, the predetermined flow rate of the clean gas and the speed of the target gas generated by the gas source module 120 are adjusted to adjust the concentration of the gas to be measured to the target concentration.

[0110] The following describes in detail how to detect the concentration of the gas to be detected by the gas concentration detection device 200.

[0111] First, the basic principle of the gas concentration detection device 200 is described.

[0112] Figure 7is a first equivalent circuit diagram of a gas concentration detection device provided in an embodiment of the present application, such as Figure 7 As shown, R g is the gas diffusion impedance, which is mainly affected by the structure of the gas diffusion channel (i.e., the gas channel 230) and is relatively stable. d is the double-layer capacitance of the electrode, which affects the transient current of the gas concentration detection device 200 (the steady-state current is not affected and Cd can be ignored in the steady-state response), R r To detect the device reaction kinetic impedance, it corresponds to the detection device reaction kinetic process and is related to the catalyst activity. Changes in catalyst activity will lead to R r Changes, which in turn lead to fluctuations in the response of the gas concentration detection device 200. If the response of the gas concentration detection device 200 is completely controlled by gas diffusion (at this time Rr = 0, such as gas diffusion through capillaries), its response current satisfies formula (1):

[0113]

[0114] Among them, k is the response sensitivity, I is the total current passing through the equivalent circuit, n is the number of response electrons, D is the gas diffusion coefficient, F is the Faraday constant, A is the apparent area of ​​the diffusion channel, L is the apparent thickness of the diffusion channel, and C is the gas concentration.

[0115] According to this Figure 7 The equivalent circuit can be obtained from formula (2):

[0116]

[0117] Where n is the number of response electrons, D is the gas diffusion coefficient, F is the Faraday constant, A is the apparent area of ​​the diffusion channel, L is the apparent thickness of the diffusion channel, and R is g is the gas diffusion resistance.

[0118] When the response of the gas concentration detection device 200 is controlled by the mixed process of gas diffusion and detection device reaction, R r ≠0 (for example, the response of the detection device is linear). According to the first equivalent circuit, formula (3) can be obtained:

[0119]

[0120] Among them, k is the response sensitivity, I is the total current passing through the equivalent circuit, C is the gas concentration, Rg is the gas diffusion impedance, and Rr is the reaction kinetic impedance of the detection device.

[0121] Figure 8 : is a second equivalent circuit schematic diagram provided in an embodiment of the present application (equivalent circuit in steady-state response, ignoring Cd), such as Figure 8As shown, according to formula (3), a second equivalent circuit can be designed, wherein branch A is the branch where the first detection device 210 is located, branch B is the branch where the second detection device 220 is located, and R m is the impedance of branch A (including electrochemical reaction impedance), R n is the impedance of branch B (including electrochemical reaction impedance). Within a certain gas concentration range, the response of the gas concentration detection device 200 to the gas concentration is linear. According to the equivalent circuit:

[0122]

[0123] Where C is the gas concentration, k is the response sensitivity, I is the total current passing through the equivalent circuit, Rg is the gas diffusion impedance, Rr is the reaction kinetic impedance of the detection device, and R r It is related to the catalyst activity in the gas concentration detection device 200. Changes in catalyst activity will cause R r changes, which in turn causes fluctuations in sensor response, R m is the impedance of the first detection device 210, and Rn is the impedance of the second detection device 220.

[0124] Fig. 9 is a flow chart of a gas concentration detection method provided in an embodiment of the present application. The method can be used Figures 1 to 3 The gas concentration detection device 200 shown in the figure is used for the gas concentration detection method, and the gas concentration detection method includes:

[0125] Step S710: Perform measurement by the first detection device 210 alone to obtain the first response current of the gas to be detected measured by the first detection device 210; at this time, the first detection device 210 works independently, the second detection device 220 does not work, and the current passing through the second detection device 220 is 0, satisfying formula (5):

[0126] R g +R m =C / I 210a ; (5)

[0127] At this time I 220a =0,

[0128] Where C is the concentration of the gas to be measured, I 210a is the first response current (i.e., the current passing through the first detection device 210), I 220a is the current passing through the second detection device 220, R g is the gas diffusion resistance.

[0129] Step S720: The first detection device 210 and the second detection device 220 are used to perform a measurement together to obtain a second response current of the gas to be detected measured by the first detection device 210; since the first detection device 210 and the second detection device 220 are in the same detection environment (for example, the same electrolyte 250), the gas diffusion impedance R g The first detection device 210 and the second detection device 220 are basically the same, and their response impedances during operation are basically consistent. At this time, the first detection device 210 and the second detection device 220 work together to satisfy formula (6):

[0130] I 210c =I 220c ; (6)

[0131] Among them, I 210c is the current passing through the first detection device 210 during the joint measurement, I 220c is the current passing through the second detection device 220 during joint measurement.

[0132] Therefore, at this time, only the second response current of the gas to be measured measured by the first detection device 210 needs to be obtained; when only the second response current of the gas to be measured measured by the first detection device 210 is obtained, formula (7) is satisfied:

[0133]

[0134] Combining formulas (6) and (7), we can get:

[0135]

[0136] Where C is the concentration of the gas to be measured, I 210c is the second response current, I 220c is the current passing through the second detection device 220 during the joint measurement, R g is the gas diffusion resistance.

[0137] The impedance of the first detection device 210 and the second detection device 220 determines the current passing through them, that is, the first detection device 210 and the second detection device 220 and their impedances satisfy Formula (9):

[0138] I 210c R m =I 220c R n ; (9)

[0139] Combining formulas (6) and (9) we can obtain:

[0140] I 210c R m =I 210c R n ; (10)

[0141] Step S730: Determine the concentration of the gas to be measured according to the gas diffusion impedance of the gas concentration detection device 200 calibrated in advance, as well as the first response current and the second response current. The concentration C of the gas to be measured can be obtained by solving formulas (5), (8), and (10) together:

[0142]

[0143] Where C is the concentration of the gas to be measured, I 210a is the first response current, I 210c is the second response current, R g is the gas diffusion resistance.

[0144] The method of the present invention only needs to calibrate the gas diffusion impedance of the gas concentration detection device 200 once in advance, and combined with the first response current and the second response current measured by the first detection device 210 and the second detection device 220, it can stably and accurately measure the gas concentration when the sensitivity of the first detection device 210 and the second detection device 220 drifts.

[0145] In one embodiment, Fig.10 is a schematic diagram of a first scheme for calibrating gas diffusion impedance provided by an embodiment of the present application, such as Fig.10 As shown, before step S730: determining the concentration of the gas to be measured according to the gas diffusion impedance of the gas concentration detection device 200 calibrated in advance, and the first response current and the second response current, the method further includes:

[0146] Step S810: The first sample response current of the sample gas of known concentration is detected by the first detection device 210; when the sample gas of known concentration passes through the first detection device 210 alone, the current passing through the first detection device 210 is the first sample response current, and the first sample response current is I1, which satisfies formula (12):

[0147]

[0148] Wherein, C1 is the known gas concentration, I1 is the current passing through the first detection device 210, and R g is the gas diffusion resistance, R m is the impedance of the first detection device 210 .

[0149] Step S820: The second sample response current and the third sample response current of the sample gas are detected by the first detection device 210 and the second detection device 220; when the sample gas of known concentration passes through the first detection device 210 and the second detection device 220 at the same time, the current passing through the first detection device 210 is the second sample response current, the second sample response current is I2, and the current passing through the second detection device 220 is the third sample response current, the third sample response current is I3, satisfying formula (13):

[0150]

[0151] Where C1 is the known gas concentration, R g is the gas diffusion impedance, I2 is the current passing through the second detection device 220, R m is the impedance of the first detection device 210, R n is the impedance of the second detection device 220.

[0152] Step S830: determining the gas diffusion impedance of the gas concentration detection device 200 according to the known concentration, the first sample response current, the second sample response current and the third sample response current;

[0153] The impedance of the first detection device 210 and the impedance of the second detection device 220 determine the current passing through the first detection device 210 and the second detection device 220, that is, formula (14):

[0154] I2R m =I3R n ; (14)

[0155] By combining formulas (12), (13) and (14), the gas diffusion impedance of the gas concentration detection device 200 can be calculated:

[0156]

[0157] Among them, R g is the gas diffusion impedance, C1 is the known gas concentration, I1 is the first sample response current (i.e., the current passing through the first detection device 210 in step S410), I2 is the second sample response current (i.e., the current passing through the first detection device 210 in step S420), I3 is the third sample response current (i.e., the current passing through the second detection device 220 in step S420), R m is the impedance of the first detection device 210, R n is the impedance of the second detection device 220.

[0158] In one embodiment, Fig.11 is a schematic diagram of a second method for calibrating gas diffusion impedance provided by an embodiment of the present application, Fig.12 This is provided by an embodiment of the present application Fig.11 The current potential scheme of the corresponding schematic diagram is as follows Figure 1-12 As shown, before step S730: determining the concentration of the gas to be measured according to the gas diffusion impedance of the gas concentration detection device 200 calibrated in advance, and the first response current and the second response current, the method further includes:

[0159] Step S910: Control the first detection device 210 and the second detection device 220 to be at an initial potential E1, and detect and obtain a first sample initial current I of the sample gas through the first detection device 210. 10 and the second sample initial current I 20 Wherein, the initial potential E1 is selected according to the application environment characteristics of the first detection device 210 and the second detection device 220, ensuring that the first sample initial current I measured at the initial potential E1 10 and the second sample initial current I 20 The current is basically the same in a clean and measured environment.

[0160] Before executing step S910, the following may also be included: step S900: controlling the first detection device 210 and the second detection device 220 to be at the cleaning potential E0, and the first detection device 210 and the second detection device 220 work, at which time the first detection device 210 and the second detection device 220 respectively reach the first cleaning current I 1c and the second cleaning current I 2c , clean the impurities in the first detection device 210 and the second detection device 220 to improve the repeatability and stability of the measurement. Wherein, when the first detection device 210 and the second detection device 220 are electrodes, the surface state of the electrode is updated by the cleaning potential E0 and the impurities in the electrolyte 250 or the electrolyte 251 where the first detection device 210 and the second detection device 220 are located are cleaned.

[0161] Step S920: Control the first detection device 210 to be at the first working potential E2. During the time period t1-t2, the second detection device 220 is still at the initial potential E1. The gas to be tested passes through the first detection device 210, and the first sample working current I of the sample gas is detected. 1a , in steady state it satisfies formula (16):

[0162]

[0163] Where C1 is the known gas concentration, I 1a is the first sample operating current, I 10 is the initial current of the first sample, R m is the electrochemical reaction impedance of the first detection device 210, Rg is the gas diffusion resistance.

[0164] Step S930: During the time period t2-t3, the first detection device 210 and the second detection device 220 are controlled to be at the first working potential E2, and the second sample working current I of the sample gas is detected by the first detection device 210. 1b And the third sample operating current I 2b ; In steady state, it satisfies formulas (17) and (18):

[0165]

[0166] (I 1b -I 10) R m =(I 2b -I 20 )R n ; (18)

[0167] Where C1 is the known gas concentration, I 1a is the first sample operating current, I 1b is the second sample operating current, I 2b is the third sample operating current, I 10 is the initial current of the first sample, I 20 is the initial current of the second sample, R m is the electrochemical reaction impedance of the first detection device 210, R g is the gas diffusion resistance.

[0168] Among them, Fig.12 As shown, the solid line represents the first sample initial current I measured by the first detection device 210 and the second detection device 220 at the initial potential E1 in the measurement environment. 10 and the second sample initial current I 20 , at this time the first sample initial current I 10 and the second sample initial current I 20 The first sample initial current I measured by the first detection device 210 and the second detection device 220 at the initial potential E1 in a clean environment 10 and the second sample initial current I 20 Therefore, the first sample initial current I measured by the first detection device 210 and the second detection device 220 at the initial potential E1 is consistent. 10 and the second sample initial current I 20 , which can be regarded as the first sample working current I measured by the first detection device 210 and the second detection device 220 at the first working potential E2 1a , the second sample working current I 1b And the third sample operating current I 2bThe zero point current.

[0169] Furthermore, during the continuous operation of the first detection device 210 and the second detection device 220, the potential can be adjusted to the initial potential E1 at any time as needed to correct the drift of the zero-point current. When the zero-point current drifts too large and exceeds a certain threshold, the potential can be controlled to reach the cleaning potential E0, and the cleaning program can be started for cleaning and updating to return the zero-point current to a normal level. If cleaning cannot return the zero point to a normal level, the detection device can be replaced.

[0170] Step S940: Based on the known concentration and the first sample initial current I 10 , the second sample initial current I 20 , the first sample working current I 1a , the second sample working current I 1b And the third sample operating current I 2b , determine the gas diffusion impedance of the gas concentration detection device 200; that is, by combining equations (16), (17), and (18), we can obtain:

[0171]

[0172] Among them, R g is the gas diffusion impedance, C1 is the known gas concentration, I 10 is the initial current of the first sample, I 20 is the initial current of the second sample, I 1a is the first sample operating current, I 2b is the second sample operating current, I 1b This is the third sample operating current.

[0173] In one embodiment, Fig.13 This is provided by an embodiment of the present application Fig.11 The corresponding schematic diagram of the current potential scheme 2 is as follows: Figure 1-13 As shown, in step S940: according to the known concentration, the first sample initial current I 10 , the second sample initial current I 20 , the first sample working current I 1a , the second sample working current I 1b And the third sample operating current I 2b After determining the gas diffusion impedance of the gas concentration detection device 200, it also includes step S950.

[0174] Step S950: After time point t4, the potential of the second detection device 220 is adjusted to the second working potential E3, thereby adjusting the amplification factor β of the first detection device 210 and improving the sensitivity of the first detection device 210; at the second working potential E3, if a reversible electrochemical oxidation reaction occurs on the first detection device 210, the product molecules oxidized by the first detection device 210 will diffuse to the second detection device 220, be reduced by the second detection device 220, and then diffuse back to the first detection device 210 to continue to be oxidized, resulting in the first sample working current I of the first detection device 210 1a Increase to become the fourth sample working current I 1c , the third sample operating current I of the second detection device 220 2b Increase to become the fifth sample working current I 2c , the magnification β can be obtained by formula (20):

[0175]

[0176] Among them, I 1a The working current of the first sample increases, I 1c is the fourth sample operating current, I 10 is the initial current of the first sample, β is the amplification factor (ie, the ratio of the increase in the working current of the first detection device 210). The change in the amplification factor β can guide the material selection and improvement of the first detection device 210, so that the first detection device 210 achieves higher sensitivity and stability.

[0177] In one embodiment, step S320: when the first detection device 210 and the second detection device 220 are used to perform measurement together, the method further includes: obtaining a third response current of the gas to be measured measured by the second detection device 220;

[0178] Step S730: determining the concentration of the gas to be measured according to the gas diffusion impedance of the gas concentration detection device 200 calibrated in advance, as well as the first response current and the second response current, including:

[0179] According to the gas diffusion impedance of the gas concentration detection device 200 calibrated in advance, as well as the first response current, the second response current and the third response current, the concentration of the gas to be measured is determined using formula (21):

[0180]

[0181] Among them, R g is the gas diffusion impedance, C is the concentration of the gas to be measured, I 210a is the first response current, I 210 c is the second response current, I 220c is the third response current.

[0182] The present application uses a gas generating device 1 and a programmed measurement method to measure gas concentration without being affected by changes in sensor sensitivity, thereby improving measurement accuracy and reliability; applying it to a standard gas generator reduces its design difficulty and expands the types of gases that can be generated; while realizing the miniaturized design of the sensor, it also realizes self-diagnosis, self-repair (self-cleaning), zero point self-correction, sensitivity self-calibration and signal amplification of the gas sensor performance, greatly improving the stability and intelligence level of micro-electrochemical gas sensing, and can perform sensor calibration, maintenance and replacement as needed, solving multiple pain points in the application of micro-electrochemical gas sensors.

[0183] It should be noted that, in the absence of conflict, the features in the embodiments of the present application can be combined with each other. The above are only preferred embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A gas concentration detection method, characterized in that: The method is performed by a gas concentration detection device, which includes a gas channel and a first detection device and a second detection device connected to the gas channel; the method includes: Performing measurement using the first detection device alone to obtain a first response current of the gas to be measured measured by the first detection device; The first detection device and the second detection device are used to perform measurement together to obtain a second response current of the gas to be detected measured by the first detection device; The concentration of the gas to be measured is determined according to the pre-calibrated gas diffusion impedance of the gas concentration detection device, as well as the first response current and the second response current.

2. A gas concentration detection method according to claim 1, characterized in that: Before determining the concentration of the gas to be measured based on the gas diffusion impedance of the gas concentration detection device calibrated in advance, and the first response current and the second response current, the method further includes: Detecting and obtaining a first sample response current of a sample gas of known concentration by the first detection device; By means of the first detection device and the second detection device, a second sample response current and a third sample response current of the sample gas are detected; The gas diffusion impedance of the gas concentration detection device is determined according to the known concentration, the first sample response current, the second sample response current and the third sample response current.

3. The method according to claim 2, characterized in that The gas diffusion impedance of the gas concentration detection device is determined according to the known concentration, the first sample response current, the second sample response current and the third sample response current, using the following formula: Among them, R g is the gas diffusion impedance, C1 is the known gas concentration, I1 is the first sample response current, I2 is the second sample response current, and I3 is the third sample response current.

4. The method according to claim 1, characterized in that: Before determining the concentration of the gas to be measured based on the gas diffusion impedance of the gas concentration detection device calibrated in advance, and the first response current and the second response current, the method further includes: Controlling the first detection device and the second detection device to be at an initial potential, and detecting and obtaining a first sample initial current and a second sample initial current of the sample gas through the first detection device; controlling the first detection device to be at a working potential, and detecting and obtaining a first sample working current of the sample gas through the first detection device; Controlling the first detection device and the second detection device to be at a working potential, and detecting and obtaining a second sample working current and a third sample working current of the sample gas through the first detection device; The gas diffusion impedance of the gas concentration detection device is determined according to the known concentration, the first sample initial current, the second sample initial current, the first sample operating current, the second sample operating current and the third sample operating current.

5. The method according to claim 4, characterized in that Before controlling the first detection device and the second detection device to be at an initial potential and detecting and obtaining a first sample initial current and a second sample initial current of the sample gas through the first detection device, the method further includes: The first detection device and the second detection device are controlled to be at a cleaning potential to clean impurities in the first detection device and the second detection device.

6. The method according to claim 4, characterized in that The gas diffusion impedance of the gas concentration detection device is determined according to the known concentration, the first sample initial current, the second sample initial current, the first sample working current, the second sample working current and the third sample working current, using the following formula: Among them, R g is the gas diffusion impedance, C1 is the known gas concentration, I 10 is the initial current of the first sample, I 20 is the initial current of the second sample, I 1a is the first sample operating current, I 2b is the second sample operating current, I 1b This is the third sample operating current.

7. The method according to claim 1, characterized in that The concentration of the gas to be measured is determined based on the gas diffusion impedance of the gas concentration detection device calibrated in advance, as well as the first response current and the second response current, and is calculated using the following formula: Among them, R g is the gas diffusion impedance, C is the concentration of the gas to be measured, I 210a is the first response current, I 210c is the second response current.

8. The method according to claim 1, characterized in that When the first detection device and the second detection device are used together for measurement, the method further includes: obtaining a third response current of the gas to be measured measured by the second detection device; The step of determining the concentration of the gas to be measured based on the pre-calibrated gas diffusion impedance of the gas concentration detection device, and the first response current and the second response current comprises: The concentration of the gas to be measured is determined based on the pre-calibrated gas diffusion impedance of the gas concentration detection device, as well as the first response current, the second response current and the third response current.

9. The method according to claim 8, characterized in that The step of determining the concentration of the gas to be measured based on the pre-calibrated gas diffusion impedance of the gas concentration detection device, and the first response current, the second response current, and the third response current comprises: Among them, R g is the gas diffusion impedance, C is the concentration of the gas to be measured, I 210a is the first response current, I 210c is the second response current, I 220c is the third response current.

10. A method for generating a gas of a target concentration, characterized in that: The method is performed by a standard gas generating device, the standard gas generating device comprises a gas distribution module, a gas source module connected to the gas distribution module, a transmission channel connected to the gas source module, a gas concentration detection device connected to the transmission channel, the gas concentration detection device comprises a gas channel and a first detection device and a second detection device connected to the gas channel; The gas channel is connected to the transmission channel; the method comprises: Control the gas distribution module to generate a predetermined flow of clean gas to enter the gas source module, control the gas source module to generate a target gas, and the clean gas and the target gas are mixed into a gas to be tested; Detecting the concentration of the gas to be measured by the method according to any one of claims 1 to 9; When the concentration of the gas to be measured is different from the target concentration, the predetermined flow rate of the clean gas and the speed of the target gas generated by the gas source module are adjusted to adjust the concentration of the gas to be measured to the target concentration.

11. A device for generating a gas with a target concentration, characterized in that: include: A gas distribution module, used to generate a predetermined flow of clean gas to enter the gas source module; A gas source module, connected to the gas distribution module, for generating target gas; A transmission channel, connected to the gas source module, for transmitting the target gas and the clean gas; A gas concentration detection device, the gas concentration detection device comprising a gas channel and a first detection device and a second detection device connected to the gas channel; the gas channel is connected to the transmission channel; An intelligent control module is connected to the gas distribution module, the gas source module and the gas concentration detection device, and the intelligent control module is used to execute the method described in claim 10.

12. The device according to claim 11, characterized in that The gas channel of the gas concentration detection device comprises: A first diffusion channel; The gas concentration detection device also includes: A first buffer chamber, wherein one end of the first buffer chamber is connected to the first diffusion channel, and the other end of the first detection device and the second detection device are respectively connected.

13. The device according to claim 12, characterized in that The gas concentration detection device also includes: a first reference electrode; a first pair of electrodes; An electrolyte, one end of which is respectively connected to the first detection device and the second detection device, and the other end of which is respectively connected to the first reference electrode and the first pair of electrodes.

14. The device according to claim 13, characterized in that The gas concentration detection device also includes: An electrode support membrane, one end of which is connected to the first buffer chamber, and the other end of which is respectively connected to the first detection device and the second detection device.

15. The device according to claim 13, characterized in that The gas concentration detection device also includes: A third detection device, one end of which is connected to one end of the electrolyte and is used to monitor changes in gas concentration; The gas channel also includes: a second buffer chamber, wherein the second buffer chamber is connected to the third detection device; A second diffusion channel is connected to the second buffer chamber.

16. The device according to claim 11, characterized in that Also includes: A gas concentration change monitoring module is connected to the transmission channel and is used to monitor gas concentration changes.

17. The device according to claim 12, characterized in that The gas concentration detection device also includes: Electrolytes; A second pair of electrodes and a second reference electrode, wherein the second pair of electrodes and the second reference electrode are separated from the first detection device and the second detection device by the electrolyte; An inert substrate is connected to one end of the electrolyte and is used to improve the stability of the gas concentration detection device.

18. The device according to claim 12, characterized in that The gas concentration detection device also includes: A heating substrate is connected to the inert substrate and is used to perform constant temperature control on the gas concentration detection device.

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