Lead-free oxygen sensor

Abstract

The application relates to a lead-free oxygen sensor, comprising: a housing; the electrode assembly comprises a working electrode, a reference electrode and a counter electrode which are arranged in sequence; the air inlet channel is used for providing a channel for external oxygen to enter the accommodating cavity to be in contact with the working electrode; the first gas outlet channel is used for providing a channel for transmitting oxygen generated by the electrode to the outside; the second gas outlet channel is used for providing a channel for transmitting oxygen generated by the electrode to the outside; wherein the first air outlet channel is provided with a first oxygen permeation membrane, and the second air outlet channel is provided with a second oxygen permeation membrane; the air permeability of the first oxygen permeable membrane is greater than that of the second oxygen permeable membrane. The internal oxygen concentration is maintained by controlling the oxygen outlet speed of the first gas outlet channel and the second gas outlet channel, so that the internal gas pressure balance is ensured while the side reaction is inhibited and the current is balanced, and the oxygen generated by the counter electrode does not permeate into the working electrode to influence the test; therefore, a larger linear test range can be realized in an actual test.

Description

Technical Field

[0001] This application relates to the technical field of electrochemical sensors, and in particular to a lead-free oxygen sensor. Background Art

[0002] Electrochemical sensors are widely used in the detection of oxygen concentration or content due to their advantages such as good reliability, reproducibility, low power consumption and easy miniaturization.

[0003] Currently, commonly used electrochemical oxygen sensors on the market contain the toxic substance lead. Because lead gradually oxidizes into lead oxide during the process, the sensor's lifespan is generally only 2-3 years. To provide sensors with a longer lifespan, lead-free oxygen sensors have emerged in recent years. These sensors often use precious metals as catalysts for the oxidation-reduction of oxygen, with no consumption during the process and a long lifespan. Lead-free oxygen sensors in related technologies mainly consist of a housing, electrode components inside the housing, and an electrolyte inside the housing. The housing also has an inlet for oxygen to enter and react with the electrode components.

[0004] Lead-free oxygen sensors in related technologies have a linear concentration range of 0-30%, which limits their application. This limitation is due to the strong catalytic effect of precious metals; once the oxygen concentration reaches a certain level, a side reaction will occur: O2 + 2H+. + +2e - →H₂O₂;H₂O₂+2H + +2e - →2H2O; 2H2O2→O2+2H2O. This side reaction is similar to a reversible reaction. The reaction is accelerated when the concentration of reactant (O2) increases or decreases when the concentration of product (O2) decreases, and inhibited when the concentration of reactant (O2) decreases. As a result, the test results under high oxygen concentration usually show a non-linear relationship and the response curve is not easy to reach equilibrium, which reduces the linear test range of the sensor. Utility Model Content

[0005] To expand the linearity testing range, this application provides a lead-free oxygen sensor.

[0006] The lead-free oxygen sensor provided in this application adopts the following technical solution:

[0007] A lead-free oxygen sensor includes: a housing having a receiving chamber; an electrode assembly disposed within the receiving chamber; the electrode assembly includes a working electrode, a reference electrode, and a counter electrode arranged sequentially, and diaphragms are provided between the working electrode and the reference electrode, between the reference electrode and the counter electrode, and between the counter electrode and the inner wall of the receiving chamber, the diaphragms being capable of adsorbing electrolyte; an air inlet channel communicating with an opening of the receiving chamber near the working electrode, for providing a channel for external oxygen to enter the receiving chamber and contact the working electrode; and a first air outlet channel communicating with the receiving chamber. The opening of the chamber is close to the counter electrode, providing a channel for the oxygen generated by the counter electrode to be transferred to the outside; a second outlet channel is connected to the opening of the receiving chamber close to the counter electrode, providing a channel for the oxygen generated by the counter electrode to be transferred to the outside; three electrical connectors are provided on the housing, one end of each connector is exposed, and the other end is connected to the working electrode, the reference electrode, and the counter electrode respectively; wherein, the first outlet channel is provided with a first oxygen-permeable membrane, and the second outlet channel is provided with a second oxygen-permeable membrane; the permeability of the first oxygen-permeable membrane is greater than the permeability of the second oxygen-permeable membrane.

[0008] By adopting the above technical solution, during actual testing and / or use of the sensor, oxygen enters the containment chamber through the air inlet channel and comes into contact with the working electrode. The working electrode catalyzes the reduction of oxygen, while the reference electrode maintains a constant potential with the working electrode. Simultaneously, the counter electrode catalyzes the production of oxygen from water, and the oxygen produced by the counter electrode gradually accumulates and diffuses around the counter electrode. The membrane adsorbed with electrolyte can prevent oxygen from freely passing through the membrane, that is, the membrane can prevent the diffusion of oxygen from the working electrode to the reference electrode and the counter electrode, thereby preventing the transfer of external oxygen to the counter electrode and thus avoiding the inhibition of the catalytic reaction at the counter electrode. At the same time, the membrane can also prevent the diffusion of oxygen produced at the counter electrode to the reference electrode and the working electrode, that is, prevent the transfer of oxygen produced by the counter electrode catalyzing water to the working electrode within the sensor, thereby avoiding the acceleration of the reduction reaction at the working electrode. Furthermore, a first and a second exhaust channel are provided to facilitate the transfer of oxygen generated by the counter electrode to the outside. By setting a first and a second oxygen-permeable membrane, the permeability of the first exhaust channel is greater than that of the second exhaust channel. When oxygen is generated at the counter electrode, creating an internal and external pressure difference, most of the oxygen is discharged to the outside through the first exhaust channel with higher permeability. As the oxygen production gradually increases and the internal and external pressure difference gradually increases, the amount of oxygen discharged through the first exhaust channel increases accordingly. At the same time, the second exhaust channel also participates more in the oxygen discharge process, thereby achieving internal pressure balance more quickly and maintaining the oxygen concentration at the counter electrode at the concentration required to achieve internal pressure balance. This suppresses side reactions at the counter electrode. Specifically, for testing environments with different oxygen concentrations, in low-oxygen-concentration testing environments, the oxygen production rate at the counter electrode is low, resulting in a low internal and external pressure difference when internal pressure equilibrium is reached. At this time, the produced oxygen is mainly discharged to the outside through the first outlet channel to maintain a low oxygen concentration at the counter electrode. This low oxygen concentration testing environment provides low suppression of side reactions, leading to a better balance in the response curve. As the oxygen concentration in the testing environment increases, the oxygen production rate at the counter electrode gradually increases, resulting in a higher internal and external pressure difference. Correspondingly, oxygen is discharged to the outside through both the first and second outlet channels simultaneously to quickly reach internal pressure equilibrium. As the oxygen concentration in the testing environment increases, the internal oxygen level also gradually increases when internal pressure equilibrium is reached, further suppressing the occurrence of side reactions and resulting in a better balance in the response curve. Therefore, compared to not setting an outlet channel, this scheme, by setting different oxygen discharge rates for the first and second outlet channels, can achieve internal pressure equilibrium in a wider range of oxygen concentrations. Furthermore, as the oxygen concentration in the testing environment increases, a higher concentration of oxygen accumulates at the counter electrode to suppress side reactions, thereby enabling the sensor to achieve a wider linear testing range.

[0009] Furthermore, the first air outlet channel includes a first air storage section, a first connecting section, and a second connecting section. The first connecting section is used to connect the first air storage section and the receiving chamber, and the second connecting section is used to connect the first air storage section and the outside.

[0010] By adopting the above technical solution, the first gas storage section can store the oxygen generated by the counter electrode, reducing the situation where too much oxygen accumulates at the counter electrode and affects its catalytic reaction. At the same time, the first gas storage section is located in one section of the first gas outlet channel and also serves as part of the oxygen discharge channel. Storing oxygen in the first gas storage section also facilitates timely discharge to the outside from the second connecting section after the concentration rises to a certain value.

[0011] Furthermore, the housing includes a first shell and a second shell that are fastened together. The first shell is provided with a first receiving groove and a first gas storage groove, and a first communicating groove is provided between the first receiving groove and the first gas storage groove. The second shell is provided with a second receiving groove and a second gas storage groove, and a second communicating groove is provided between the second receiving groove and the second gas storage groove. When the first shell and the second shell are fastened together, the first receiving groove and the second receiving groove are combined to form the receiving chamber, the first gas storage groove and the second gas storage groove are combined to form the first gas storage section, and the first communicating groove and the second communicating groove are combined to form the first communicating section.

[0012] By adopting the above technical solution, the entire shell is composed of a first shell and a second shell that interlock, and a cavity is formed in the shell by setting grooves at the opposite positions of the first shell and the second shell. Compared with the shell having an internal cavity, this solution can effectively reduce the manufacturing difficulty and manufacturing cost.

[0013] Furthermore, a liquid storage chamber is provided on the lower side of the counter electrode, and the liquid storage chamber is connected to the outside and the receiving chamber via a second venting channel.

[0014] By adopting the above technical solution, the liquid storage chamber can provide an area for storing electrolyte and can also serve as an oxygen collection area in the first gas outlet channel, reducing the possibility of oxygen accumulating on the counter electrode and affecting its catalytic reaction.

[0015] Further, the housing includes a snap-fit ​​upper shell and a lower shell. The upper shell has an upper recessed groove, and the lower shell includes a bottom shell, a support member, and a liquid injection sealing member. The bottom shell has a lower recessed groove at the top and a liquid injection channel at the bottom that connects to the lower recessed groove. The lower recessed groove and the upper recessed groove cooperate to form the receiving chamber. The support member is placed at the bottom of the lower recessed groove to support the electrode assembly located in the receiving chamber. The liquid injection sealing member is inserted into the liquid injection channel, and the upper end face of the liquid injection sealing member has a liquid storage tank. The upper opening of the liquid storage tank is blocked by the support member to form the liquid storage cavity. The support member has a first through hole that penetrates its upper and lower end faces, and the liquid injection sealing member has a second through hole that extends from the bottom of the liquid storage tank to the outside. The first through hole and the second through hole constitute the second venting channel.

[0016] By adopting the above technical solution and combining multiple components to form internal cavities, the manufacturing difficulty can be reduced, thereby reducing the manufacturing cost.

[0017] Furthermore, the second oxygen-permeable membrane is disposed at the bottom of the liquid storage cavity and at the connection point of the second through hole.

[0018] Furthermore, the air permeability of the first oxygen-permeable membrane is a, and the air permeability of the second oxygen-permeable membrane is b, where the air permeability b ≤ a / 2.

[0019] Furthermore, the air permeability α of the first oxygen-permeable membrane is 200~800 mm. 3 / (m 2 •24hr·atm); and / or, the air permeability b of the second oxygen-permeable membrane is 50~100 mm. 3 / (m 2 ·24hr·atm).

[0020] Furthermore, the air intake channel is connected to the outside by a capillary; and / or, the first air outlet channel is connected to the outside by a capillary; and / or, the second air outlet channel is connected to the outside by a capillary.

[0021] Furthermore, the first venting channel connects to the opening of the receiving chamber facing the side of the counter electrode; and / or, the second venting channel connects to the opening of the receiving chamber facing the bottom of the counter electrode, and the diaphragm is present between the bottom of the counter electrode and the opening of the second venting channel.

[0022] In summary, this application includes at least the following beneficial effects: the first and second outlet channels provide channels for the oxygen generated by the counter electrode to be transferred to the outside, and by setting the first and second oxygen-permeable membranes, the permeability of the first outlet channel is greater than that of the second outlet channel; when the counter electrode generates oxygen and creates an internal and external pressure difference, most of the oxygen is discharged to the outside through the first outlet channel with high permeability. As the oxygen production gradually increases and the internal and external pressure difference gradually increases, the amount of oxygen discharged through the first outlet channel increases accordingly, and the second outlet channel also participates more in the oxygen discharge process, thereby achieving internal pressure balance more quickly and maintaining the oxygen concentration of the counter electrode at the concentration required to achieve internal pressure balance, thereby suppressing side reactions at the counter electrode. Specifically, for testing environments with different oxygen concentrations, in low-oxygen-concentration testing environments, the oxygen production rate at the counter electrode is low, resulting in a low internal and external pressure difference when internal pressure equilibrium is reached. At this time, the produced oxygen is mainly discharged to the outside through the first outlet channel to maintain a low oxygen concentration at the counter electrode. This low oxygen concentration testing environment provides low suppression of side reactions, leading to a better balance in the response curve. As the oxygen concentration in the testing environment increases, the oxygen production rate at the counter electrode gradually increases, resulting in a higher internal and external pressure difference. Correspondingly, oxygen is discharged to the outside through both the first and second outlet channels simultaneously to quickly reach internal pressure equilibrium. As the oxygen concentration in the testing environment increases, the internal oxygen level also gradually increases when internal pressure equilibrium is reached, further suppressing the occurrence of side reactions and resulting in a better balance in the response curve. Therefore, compared to not setting an outlet channel, this scheme, by setting different oxygen discharge rates for the first and second outlet channels, can achieve internal pressure equilibrium in a wider range of oxygen concentrations. Furthermore, as the oxygen concentration in the testing environment increases, a higher concentration of oxygen accumulates at the counter electrode to suppress side reactions, thereby enabling the sensor to achieve a wider linear testing range. Attached Figure Description

[0023] Figure 1 This is an overall schematic diagram of an oxygen sensor in one embodiment of this application;

[0024] Figure 2 This is a cross-sectional view of an oxygen sensor in one embodiment of this application;

[0025] Figure 3 This is a top view of an oxygen sensor in one embodiment of this application;

[0026] Figure 4 This is a cross-sectional view of an oxygen sensor in another embodiment of this application.

[0027] Explanation of reference numerals in the attached drawings: 1. Shell; 11. First shell; 12. Second shell; 13. Upper shell; 14. Lower shell; 141. Bottom shell; 142. Support member; 1421. First through hole; 143. Liquid injection sealing member; 1431. Second through hole; 144. Liquid storage chamber; 2. Electrode assembly; 21. Working electrode; 22. Reference electrode; 23. Counter electrode; 3. Conductive pin; 4. Air inlet channel; 5. First air outlet channel; 51. First gas storage section; 52. First connecting section; 53. Second connecting section; 6. Second air outlet channel; 7. First oxygen permeable membrane; 8. Second oxygen permeable membrane; 9. Diaphragm. DETAILED DESCRIPTION

[0028] The embodiments of this utility model are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this utility model, and should not be construed as limiting this utility model.

[0029] In the description of this utility model, it should be understood that the terms "center," "longitudinal," "transverse," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "axial," "radial," and "circumferential," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing this utility model and simplifying the description. They do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. Furthermore, features defined with "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this utility model, unless otherwise stated, "a plurality of" means two or more.

[0030] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0031] This application discloses a lead-free oxygen sensor.

[0032] Reference Figure 1 and Figure 2A lead-free oxygen sensor includes a housing 1, an electrode assembly 2, electrical connectors, an air inlet channel 4, a first air outlet channel 5, and a second air outlet channel 6. The housing 1 has a built-in receiving chamber capable of holding an electrolyte. Correspondingly, the electrode assembly 2 is disposed within the receiving chamber. In this embodiment, the electrode assembly 2 includes a working electrode 21, a reference electrode 22, and a counter electrode 23 arranged sequentially from top to bottom. A diaphragm 9 is provided between the working electrode 21 and the reference electrode 22, between the reference electrode 22 and the counter electrode 23, and between the counter electrode 23 and the inner wall of the receiving chamber. The diaphragm 9 can absorb the electrolyte, allowing the working electrode 21, the reference electrode 22, and the counter electrode 23 to contact the electrolyte, while also hindering the free transfer of oxygen between adjacent electrodes. Furthermore, three electrical connectors are disposed on the housing 1. One end of each connector is exposed for connection to a circuit board, and the other end is connected to the working electrode 21, the reference electrode 22, and the counter electrode 23 respectively.

[0033] Reference Figure 1 The air inlet channel 4, the first air outlet channel 5, and the second air outlet channel 6 are all provided on the housing 1. The air inlet channel 4 is used to provide a channel for external oxygen to enter the receiving chamber and contact the working electrode 21, and its opening to the receiving chamber is close to the working electrode 21. The first air outlet channel 5 is used to provide a channel for oxygen generated by the counter electrode 23 to be transferred to the outside, and its opening to the receiving chamber is close to the counter electrode 23. The second air outlet channel 6 is used to provide a channel for oxygen generated by the counter electrode 23 to be transferred to the outside, and its opening to the receiving chamber is close to the counter electrode 23. The first air outlet channel 5 is provided with a first oxygen permeable membrane 7, and the second air outlet channel 6 is provided with a second oxygen permeable membrane 8. The permeability of the first oxygen permeable membrane 7 is greater than the permeability of the second oxygen permeable membrane 8.

[0034] Using the above scheme, during sensor testing, oxygen enters the containment chamber through the air inlet channel 4 and comes into contact with the working electrode 21. The working electrode 21 catalyzes the reduction of oxygen. The reference electrode 22 maintains a constant potential with the working electrode 21. Simultaneously, the counter electrode 23 catalyzes the production of oxygen from water, and the oxygen produced by the counter electrode 23 gradually accumulates and diffuses around the counter electrode 23. The membrane 9, which adsorbs electrolyte, prevents oxygen from freely passing through it. That is, the membrane 9 prevents oxygen at the working electrode 21 from diffusing to the reference electrode 22 and the counter electrode 23, thereby preventing external oxygen from being transferred to the counter electrode 23 and thus avoiding the inhibition of the catalytic reaction at the counter electrode 23. At the same time, the membrane 9 prevents the oxygen produced at the counter electrode 23 from diffusing to the reference electrode 22 and the working electrode 21, that is, it prevents the oxygen produced by the counter electrode 23 catalyzing water from being transferred to the working electrode 21 within the sensor, thereby avoiding the acceleration of the reduction reaction at the working electrode 21.

[0035] Meanwhile, the above scheme provides a first exhaust channel 5 and a second exhaust channel 6 to provide channels for the oxygen generated by the counter electrode 23 to be transferred to the outside. By setting a first oxygen-permeable membrane 7 and a second oxygen-permeable membrane 8, the permeability of the first exhaust channel 5 is greater than that of the second exhaust channel 6. When the counter electrode 23 generates oxygen and creates an internal and external pressure difference, most of the oxygen is discharged to the outside through the first exhaust channel 5 with a high permeability. As the oxygen production gradually increases and the internal and external pressure difference gradually increases, the amount of oxygen discharged through the first exhaust channel 5 increases accordingly. At the same time, the second exhaust channel 6 will also participate more in the oxygen discharge process, thereby achieving internal pressure balance more quickly and maintaining the oxygen concentration of the counter electrode 23 at the concentration required to achieve internal pressure balance, thus inhibiting the side reactions at the counter electrode 23. Specifically, for test environments with different oxygen concentrations, in a low oxygen concentration test environment, the oxygen production rate at the counter electrode 23 is low, resulting in a low internal and external pressure difference when internal pressure equilibrium is achieved. At this time, the produced oxygen is mainly discharged to the outside through the first outlet channel 5 in a timely manner, thereby maintaining a low oxygen concentration at the counter electrode 23. That is, in a low oxygen concentration test environment, low inhibition of side reactions is achieved, resulting in a better balance in the response curve. As the oxygen concentration in the test environment increases, the oxygen production rate at the counter electrode 23 also gradually increases, gradually generating a higher internal and external pressure difference. Correspondingly, oxygen is discharged to the outside through the first outlet channel 5 and the second outlet channel 6 simultaneously, quickly achieving internal pressure equilibrium. As the oxygen concentration in the test environment increases, the internal oxygen concentration also gradually increases when internal pressure equilibrium is achieved, thereby further suppressing the occurrence of side reactions at the counter electrode 23, resulting in a better balance in the response curve. Therefore, compared to not setting an exhaust channel, this solution can achieve internal pressure balance in a timely manner within a wider range of oxygen concentrations by setting different oxygen exhaust rates in the first exhaust channel 5 and the second exhaust channel 6. As the oxygen concentration in the test environment increases, a higher concentration of oxygen accumulates at the counter electrode 23 to suppress side reactions, thereby enabling the sensor to obtain a larger linear test range.

[0036] It should be noted that the working electrode 21 is mainly used for catalytic reduction of oxygen, and it consists of a polymer substrate with a certain air permeability and a catalytic coating; in some specific embodiments, the air permeability of the polymer substrate constituting the working electrode 21 is preferably 10~50 mL / min cm. 2 @7Kpa, the preferred material is PTFE, and the catalytic coating constituting the working electrode 21 is preferably an ordered catalytic structure prepared from noble metals, such as platinum, gold, or ruthenium. Meanwhile, the reference electrode 22 is mainly used to maintain a constant potential with the working electrode 21, and it consists of a polymer substrate with a certain air permeability and a catalytic coating; in some specific embodiments, the air permeability of the polymer substrate constituting the reference electrode 22 is less than 10 mL / min cm⁻¹.2 @7Kpa, the preferred material is PTFE, while the catalytic coating constituting the reference electrode 22 is preferably an ordered catalytic structure prepared from noble metals, such as platinum, gold, or ruthenium. Furthermore, the counter electrode 23 is mainly used for catalytic water production of oxygen, and it consists of a polymer substrate with a certain permeability and a catalytic coating; in some specific embodiments, the permeability of the polymer substrate constituting the counter electrode 23 is less than 10 mL / min cm⁻¹. 2 @7Kpa, the commonly used material is PTFE, while the catalytic coating constituting the counter electrode 23 is preferably an ordered catalytic structure prepared from noble metals, such as platinum, gold, or ruthenium. For example, 10 mL / min cm 2 @7Kpa indicates that the gas pressure difference across the breathable material is 7Kpa, from 1 cm... 2 The volume of gas that permeates through the breathable material is 10 mL per minute.

[0037] It is understandable that the electrolyte-adsorbing membrane 9 can hinder the free transfer of oxygen, meaning that the electrolyte-adsorbing membrane 9 has a very low permeability, thus blocking oxygen from passing through the membrane 9. It should be noted that the permeability of the electrolyte-adsorbing membrane 9 is much lower than that of the working electrode 21, the reference electrode 22, and the counter electrode 23 themselves. Therefore, under the barrier of the membrane 9, oxygen will preferentially diffuse and transfer within the electrodes. In some specific embodiments, the membrane 9 is a glass fiber diaphragm.

[0038] Similarly, it is understood that the electrical connector is used to connect the external circuit to the electrode assembly 2. In some specific embodiments, the electrical connector includes conductive pins 3 and wires, wherein one end of the conductive pin 3 is exposed outside the housing 1 and the other end is inside the housing 1; while the wires are arranged inside the housing 1 to connect the conductive pins 3 to the corresponding electrodes.

[0039] It should be noted that the opening of the intake channel 4 connecting to the receiving chamber is close to the working electrode 21, meaning that the opening of the intake channel 4 is located near the working electrode 21 in the electrode assembly 2, so that oxygen via the intake channel 4 is delivered to the working electrode 21 first. Specifically, in this embodiment, the opening is directly opposite the top of the working electrode 21; while in other embodiments, the opening is directly opposite the side end of the working electrode 21.

[0040] It should also be noted that the opening of the first exhaust channel 5 and / or the second exhaust channel 6 connecting to the receiving chamber is close to the counter electrode 23. This means that the opening of the first exhaust channel 5 and / or the second exhaust channel 6 is located near the working electrode 21 in the electrode assembly 2, so that the oxygen generated at the counter electrode 23 can be transferred to the outside via the first exhaust channel 5 and / or the second exhaust channel 6. Specifically, in this embodiment, the opening of the first exhaust channel 5 is directly opposite the side end of the counter electrode 23, and the opening of the second exhaust channel 6 is directly opposite the bottom end of the counter electrode 23 and separated from the bottom end of the counter electrode 23 by a diaphragm 9. In other embodiments, the openings of the first exhaust channel 5 and the second exhaust channel 6 are both directly opposite the side end of the counter electrode 23. In other embodiments, the openings of the first exhaust channel 5 and the second exhaust channel 6 are both directly opposite the bottom end of the counter electrode 23 and separated from the bottom end of the counter electrode 23 by a diaphragm 9.

[0041] It is understandable that the first oxygen-permeable membrane 7 and the second oxygen-permeable membrane 8 are respectively set in the first air outlet channel 5 and the second air outlet channel 6 to block the free transfer of oxygen to a certain extent, thereby achieving the purpose of accumulating a certain concentration of oxygen inside the sensor to suppress side reactions. It should be noted that although the first oxygen-permeable membrane 7 and the second oxygen-permeable membrane 8 will hinder the free transfer of oxygen, their permeability is significantly lower than that of the membrane 9 after adsorbing the electrolyte. At the same time, the permeability of the second air outlet channel 6 is set to be lower than that of the first air outlet channel 5. Therefore, when oxygen is generated at the counter electrode 23, creating an internal and external pressure difference in the sensor, most of the oxygen will first be discharged to the outside through the first air outlet channel 5. When the oxygen concentration in the test environment increases, and the oxygen production rate at the counter electrode 23 increases, the resulting internal and external pressure difference also increases accordingly. At this time, oxygen is discharged to the outside through both the first air outlet channel 5 and the second air outlet channel 6 to quickly maintain the internal pressure balance. As the oxygen concentration in the test environment increases, the internal oxygen concentration also gradually increases when the internal pressure balance is achieved, thereby suppressing the occurrence of side reactions of the sensor more, so that the response curve can also reach a good balance when the oxygen concentration in the test environment is high.

[0042] For ease of description, let the air permeability of the first oxygen-permeable membrane 7 be 'a' and the air permeability of the second oxygen-permeable membrane 8 be 'b'. In some embodiments, the air permeability is set to b ≤ a / 2, which ensures that the air permeability of the first air outlet channel 5 and the second air outlet channel 6 forms a certain gradient. Accordingly, in some specific embodiments, the air permeability 'a' of the first oxygen-permeable membrane 7 is preferably 200~800 mm. 3 / (m 2 (24hr·atm), the air permeability b of the second oxygen-permeable membrane 8 is less than or equal to 100 mm. 3 / (m 2 •24hr·atm); In some other specific embodiments, the air permeability b of the second oxygen-permeable membrane 8 is preferably 50~100 mm.3 / (m 2 (24hr·atm), the air permeability a of the first oxygen-permeable membrane 7 is greater than or equal to 200 mm. 3 / (m 2 • 24hr·atm); In some other specific embodiments, the air permeability α of the first oxygen-permeable membrane 7 is preferably 200~800 mm. 3 / (m 2 (24hr·atm), the air permeability b of the second oxygen-permeable membrane 8 is preferably 50~100mm. 3 / (m 2 (24hr·atm). For example, the air permeability of the first oxygen-permeable membrane 7 is a = 200~800 mm. 3 / (m 2 The figure (24hr·atm) indicates that when the pressure difference across the first oxygen-permeable membrane 7 is one atmosphere, the volume of gas passing through 1 cubic meter of the first oxygen-permeable membrane 7 is 200~800 cubic centimeters in 24 hours. Furthermore, in some specific embodiments, the first oxygen-permeable membrane 7 is a film made of materials such as LDPE, PFA, or FEP, and the second oxygen-permeable membrane 8 is a film made of materials such as HDPE, PP, or OPP.

[0043] Meanwhile, in some embodiments, the connection point between the air intake channel 4 and the outside is a capillary; in other embodiments, the connection point between the first air outlet channel 5 and the outside is a capillary; in other embodiments, the connection point between the second air outlet channel 6 and the outside is a capillary. In some embodiments, both the connection points between the air intake channel 4 and the outside, and the connection points between the first air outlet channel 5 and the outside are capillary; in other embodiments, both the connection points between the air intake channel 4 and the outside, and the connection points between the second air outlet channel 5 and the outside are capillary; in other embodiments, both the connection points between the first air outlet channel 5 and the outside, and the connection points between the second air outlet channel 5 and the outside are capillary. In some embodiments, the connection points between the air intake channel 4 and the outside, the connection points between the first air outlet channel 5 and the outside, and the connection points between the second air outlet channel 5 and the outside are capillary. Furthermore, in specific embodiments, the diameter of the capillary is 20~50µm. (Refer to...) Figure 2 and Figure 3 In some embodiments, the air intake channel 4 is located at the top of the sensor housing 1, the first air outlet channel 5 is located at the top of the sensor housing 1, and the second air outlet channel 6 is located at the bottom of the sensor housing 1.

[0044] Furthermore, referring to Figure 2In some embodiments, the first gas outlet channel 5 includes a first gas storage section 51, a first connecting section 52, and a second connecting section 53. The first connecting section 52 connects the first gas storage section 51 to the receiving chamber, and the second connecting section 53 connects the first gas storage section 51 to the outside. By setting the first gas storage section 51, oxygen generated by the counter electrode 23 can be stored, reducing the possibility of excessive oxygen accumulation at the counter electrode 23, which could affect its catalytic reaction. At the same time, the first gas storage section 51 is located in one section of the first gas outlet channel 5 and also serves as part of the oxygen discharge channel. Storing oxygen in the first gas storage section 51 also facilitates timely discharge of oxygen to the outside through the second connecting section 53 after the concentration rises to a certain value.

[0045] Reference Figure 2 The housing 1 includes a first shell 11 and a second shell 12 that interlock. The first shell 11 has a first receiving groove and a first gas storage groove, and a first communicating groove is formed between the first receiving groove and the first gas storage groove. The second shell 12 has a second receiving groove and a second gas storage groove, and a second communicating groove is formed between the second receiving groove and the second gas storage groove. When the first shell 11 and the second shell 12 are interlocked, the first receiving groove and the second receiving groove are combined to form a receiving chamber, the first gas storage groove and the second gas storage groove are combined to form a first gas storage section 51, and the first communicating groove and the second communicating groove are combined to form a first communicating section 52. By setting the interlocking first shell 11 and the second shell 12 to form the entire housing 1, and by setting grooves at the opposite positions of the first shell 11 and the second shell 12 to form a cavity within the housing 1, compared with the housing 1 having an internal cavity, this solution can effectively reduce the manufacturing difficulty and manufacturing cost.

[0046] Furthermore, referring to Figure 4 In some embodiments, a liquid storage chamber 144 is also provided on the housing 1 below the counter electrode 23. The liquid storage chamber 144 is connected to the outside and the receiving chamber via the second venting channel 6. By providing the liquid storage chamber 144, an area for storing electrolyte can be provided, and it can also serve as an oxygen collection area in the first venting channel 5, reducing the possibility of oxygen accumulating on the counter electrode 23 and affecting its catalytic reaction.

[0047] For specific implementation examples, please refer to Figure 4The shell 1 includes an upper shell 13 and a lower shell 14 that are fastened together, and are equivalent to the aforementioned first shell 11 and second shell 12 that are fastened together. Specifically, the upper shell 13 is provided with an upper recessed groove, which is equivalent to the aforementioned first shell 11 being provided with a first receiving groove. The lower shell 14 includes a bottom shell 141, a support member 142, and a liquid injection sealing member 143. The bottom shell 141 is provided with a lower recessed groove at the top and a liquid injection channel communicating with the lower recessed groove at the bottom. The lower recessed groove and the upper recessed groove cooperate to form a receiving chamber, wherein the lower recessed groove at the top of the bottom shell 141 is equivalent to the aforementioned second shell 12 being provided with a second receiving groove. A support member 142 is placed at the bottom of the lower settling tank to support the electrode assembly 2 located within the receiving chamber. A liquid injection sealing member 143 is inserted into the liquid injection channel, and its upper end face is provided with a liquid storage tank. The upper opening of the liquid storage tank is blocked by the support member 142 to form a liquid storage cavity 144. The support member 142 has a first through hole 1421 penetrating its upper and lower end faces, and the liquid injection sealing member 143 has a second through hole 1431 penetrating from the bottom of the liquid storage tank to the outside. The first through hole 1421 and the second through hole 1431 constitute a second venting channel 6. By combining multiple components to form the internal cavity, the manufacturing difficulty can be reduced, thereby lowering the manufacturing cost.

[0048] In addition, to facilitate the installation of the second oxygen-permeable membrane 8, in some specific embodiments, the second oxygen-permeable membrane 8 is installed at the connection between the bottom of the liquid storage cavity 144 and the second through hole 1431.

[0049] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Although embodiments of the present invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A lead-free oxygen sensor, characterized in that, include: A shell having a receiving chamber; An electrode assembly is disposed within the receiving chamber; the electrode assembly includes a working electrode, a reference electrode, and a counter electrode arranged in sequence, and a diaphragm is provided between the working electrode and the reference electrode, between the reference electrode and the counter electrode, and between the counter electrode and the inner wall of the receiving chamber, the diaphragm being capable of adsorbing electrolyte; An air intake channel, which connects to the opening of the receiving chamber near the working electrode, is used to provide a channel for external oxygen to enter the receiving chamber and contact the working electrode; The first air outlet channel, which connects to the opening of the receiving chamber near the counter electrode, is used to provide a channel for the oxygen generated by the counter electrode to be transferred to the outside. The second air outlet channel, which connects to the opening of the receiving chamber near the counter electrode, is used to provide a channel for the oxygen generated by the counter electrode to be transferred to the outside. Three electrical connectors are provided on the housing, with one end of each connector exposed and the other end connected to the working electrode, the reference electrode, and the counter electrode respectively. The first air outlet channel is provided with a first oxygen-permeable membrane, and the second air outlet channel is provided with a second oxygen-permeable membrane; the air permeability of the first oxygen-permeable membrane is greater than the air permeability of the second oxygen-permeable membrane.

2. The lead-free oxygen sensor according to claim 1, characterized in that, The first air outlet channel includes a first air storage section, a first connecting section and a second connecting section. The first connecting section is used to connect the first air storage section and the receiving chamber, and the second connecting section is used to connect the first air storage section and the outside.

3. A lead-free oxygen sensor according to claim 2, characterized in that, The housing includes a first housing and a second housing that are interlocked. The first housing is provided with a first receiving groove and a first gas storage groove, and there is a first communicating groove between the first receiving groove and the first gas storage groove. The second housing is provided with a second receiving groove and a second gas storage groove, and there is a second communicating groove between the second receiving groove and the second gas storage groove. When the first shell and the second shell are fastened together, the first receiving groove and the second receiving groove are combined to form the receiving chamber, the first gas storage groove and the second gas storage groove are combined to form the first gas storage section, and the first connecting groove and the second connecting groove are combined to form the first connecting section.

4. A lead-free oxygen sensor according to claim 1, characterized in that, A liquid storage chamber is provided on the lower side of the counter electrode, and the liquid storage chamber is connected to the outside and the receiving chamber via a second venting channel.

5. A lead-free oxygen sensor according to claim 4, characterized in that, The housing includes a snap-fit ​​upper shell and a lower shell. The upper shell is provided with an upper recessed groove, and the lower shell includes a bottom shell, a support member, and a liquid injection sealing member. The bottom shell has a lower sink groove at the top and a liquid injection channel at the bottom that connects to the lower sink groove. The lower sink groove and the upper sink groove cooperate to form the receiving chamber. The support member is placed at the bottom of the lower recess and is used to support the electrode assembly located in the receiving chamber; The liquid injection sealing member is inserted into the liquid injection channel, and the upper end face of the liquid injection sealing member is provided with a liquid storage tank. The upper opening of the liquid storage tank is blocked by the support member to form the liquid storage cavity. The support member is provided with a first through hole that passes through its upper and lower end faces, and the liquid injection sealing member is provided with a second through hole that passes through the bottom of the liquid storage tank to the outside. The first through hole and the second through hole constitute the second air outlet channel.

6. A lead-free oxygen sensor according to claim 5, characterized in that, The second oxygen-permeable membrane is located at the bottom of the liquid storage cavity and at the connection point of the second through hole.

7. A lead-free oxygen sensor according to claim 1, characterized in that, The first oxygen-permeable membrane has an air permeability of a, and the second oxygen-permeable membrane has an air permeability of b, where b ≤ a / 2.

8. A lead-free oxygen sensor according to claim 7, characterized in that, The air permeability α of the first oxygen-permeable membrane is 200~800 mm. 3 / (m 2 ·24hr·atm); And / or, the air permeability b of the second oxygen-permeable membrane is 50~100 mm. 3 / (m 2 ·24hr·atm).

9. A lead-free oxygen sensor according to claim 1, characterized in that, The air intake channel is connected to the outside by capillary pores. And / or, the first air outlet channel is connected to the outside by a capillary pore; And / or, the second air outlet channel is connected to the outside by a capillary.

10. A lead-free oxygen sensor according to claim 1, characterized in that, The first venting channel is connected to the side of the receiving chamber facing the counter electrode; And / or, the second vent passage communicates with the opening of the receiving chamber facing the bottom of the counter electrode, and the diaphragm is present between the bottom of the counter electrode and the opening of the second vent passage.

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