Electrochemical sensor assembly for micro air stations

Abstract

The application discloses an electrochemical sensor assembly structure for a micro air station, which comprises an electrochemical sensor and a temperature control base, wherein the temperature control base comprises a Peltier module and a heat conduction module, the upper surface of the heat conduction module is provided with a recess, the Peltier module is arranged in the recess, and the back of the Peltier module is in close contact with the heat conduction module; a heat preservation shell is connected to the temperature control base, and the electrochemical sensor is arranged in the heat preservation shell; a filter air chamber is arranged in the heat preservation shell and below the electrochemical sensor, the filter air chamber is internally hollow to form a cavity, and the left side or the right side is provided with an inlet; the upper surface of the filter air chamber is uniformly provided with protrusions, and the tail end of each protrusion is provided with a capillary hole; the capillary hole is opposite to the electrode of the electrochemical sensor; the gas sample enters the cavity from the inlet and is sprayed from the capillary hole to contact the electrode of the electrochemical sensor. The application has the advantages of simple structure, long service life and accurate measurement.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of air quality monitoring, and particularly relates to an electrochemical sensor assembly structure for a micro air station. BACKGROUND

[0002] Most electrochemical gas sensors are applied in diffusion mode, in which the gas sample from the ambient environment enters the sensor through a small hole in the front face of the sensor (by natural flow of gas molecules). Some devices, however, draw the air / gas sample into the sensor by means of a suction pump. A Teflon membrane is installed at the gas hole to prevent water or oil from entering the sensor. The measurement range and sensitivity of the sensor can be varied by adjusting the size of the gas inlet hole at the design stage. A larger gas inlet hole can increase the sensitivity and resolution of the device, while a smaller gas inlet hole can increase the measurement range, although it reduces the sensitivity and resolution.

[0003] For example, the working principle of an oxygen sensor is similar to that of the electrochemical oxygen sensor described above, but the service life of the oxygen sensor is predictable, so the replacement cycle can also be preset - generally 2-3 years. Unlike toxic gas sensors, oxygen sensors are continuously exposed to the target gas for a long time. In a typical oxygen consumption monitoring application, the oxygen concentration in the sensor operating environment is 20.9%, which will cause a chemical reaction on the lead anode, thereby causing the anode to gradually consume. Therefore, the ability of the sensor to continuously generate current by reacting with oxygen depends on the amount of lead in the electrolyte.

[0004] The service life of an electrochemical sensor for detecting common gases such as carbon monoxide or hydrogen sulfide is usually 2-3 years. However, the service life of a sensor for some special gases, such as hydrogen fluoride gas, is only 12-18 months. The specific use will have corresponding extensions and shortenings.

[0005] By adding the key mechanism of "temperature compensation", gas detection device manufacturers ensure the performance of the sensor. Gas sensitivity (and zero baseline signal) often changes with temperature, so when the temperature rises and falls, the gas sensitivity changes nonlinearly.

[0006] In the development of gas detection devices, a lot of time is spent on placing the same gas sensor in different temperatures and different concentrations of gas (temperature between -30°C and +50°C). The collected data is processed to generate a temperature compensation algorithm for the gas detector to ensure that the sensor readings remain consistent throughout the operating range.

[0007] In ideal conditions, i.e. temperature and humidity maintained at about 20°C and 60% RH, respectively, and no intrusion of contaminants, some electrochemical sensors are known to work for more than 11 years, periodically exposed to the target gas environment without limiting the sensor's useful life. High quality sensors are usually equipped with sufficient catalyst and robust conductors that are not easily consumed by chemical reactions.

[0008] Factors affecting sensor life:

[0009] 1. Extreme temperatures can affect sensor life. At too low a temperature, the sensor's sensitivity can decrease. Perhaps the sensor can work at -40°C, but the sensitivity to the gas can decrease significantly (the sensitivity can even decrease by as much as 80%), and the response time can also be significantly prolonged. In addition, when the temperature drops below -35°C, there is a risk of freezing of the electrolyte.

[0010] 2. When the gas concentration is too high, it can also cause the sensor to degrade. Usually, the electrochemical sensor is tested at a limit gas concentration that is ten times the design concentration. The sensor using high quality catalyst should be able to withstand such a situation and not cause damage to its chemical properties or long-term performance. The sensor using low quality catalyst can be damaged.

[0011] 3. Humidity is the most important factor affecting the sensor. The ideal working environment for the electrochemical sensor should be 20°C and 60% RH (relative humidity). When the ambient humidity is greater than 60% RH, the electrolyte can be diluted by absorbing water. In extreme cases, the volume of the electrolyte can increase by 2-3 times, which can cause the electrolyte to leak from the sensor device through the interface. When the humidity is less than 60% RH, the electrolyte can be dehydrated. As the electrolyte dehydrates, the device response time can be significantly prolonged.

[0012] Currently, in the prior art, the assembly structure of the electrochemical sensor is mostly designed around the two factors of water removal drying and temperature control. Such design is nothing more than to extend the service life of the electrochemical sensor and prevent low (high) temperature from affecting the accuracy of the measurement. However, in the existing assembly structure of the electrochemical sensor, when the gas sample contacts the electrochemical sensor, the gas has a large flow rate, the flow direction of the gas sample is generally perpendicular to the electrode direction of the electrochemical sensor, and the gas sample flow has a large pulsation. The filter screen provided by the electrochemical sensor makes the sensor electrode not in good contact with the gas sample, which is not conducive to the electrode to well detect the gas sample. Therefore, the design of the prior art does not consider the real contact of the electrochemical sensor with the environmental gas to be measured, so that the detection accuracy needs to be improved.

[0013] Therefore, there is an urgent need for an electrochemical sensor assembly structure for a micro air station with long service life and high accuracy. SUMMARY

[0014] The present application aims to provide an electrochemical sensor assembly structure for a micro air station with long service life and high accuracy.

[0015] To achieve the above object, the present application provides a technical solution: an electrochemical sensor assembly structure for a micro air station, comprising an electrochemical sensor, further comprising:

[0016] A temperature control base, the temperature control base comprises a Peltier module and a heat conduction module, a recess is formed on the upper surface of the heat conduction module, the Peltier module is arranged in the recess, and the back of the Peltier module is in close contact with the heat conduction module.

[0017] A heat preservation shell connected to the temperature control base, and the electrochemical sensor is arranged in the heat preservation shell.

[0018] A filter air chamber arranged inside the heat preservation shell below the electrochemical sensor, the filter air chamber is a hollow structure forming a cavity, and an inlet is arranged on the left side or the right side, the upper surface of the filter air chamber is uniformly provided with capillary holes, the capillary holes are opposite to the electrodes of the electrochemical sensor, and the gas sample enters the cavity from the inlet and is sprayed from the capillary holes to contact the electrodes of the electrochemical sensor.

[0019] The upper surface of the filter air chamber is uniformly provided with protrusions, and the end of each protrusion is provided with a capillary hole.

[0020] The connection between the temperature control base and the heat preservation shell is provided with a vacuum structure.

[0021] The heat preservation shell comprises a plastic shell and glass fiber cotton filled in the plastic shell.

[0022] The heat conduction module is an aluminum-based heat dissipation fin.

[0023] Before entering the filter air chamber, the gas sample passes through a water removal device for water removal.

[0024] The inside of the filter air chamber is further provided with a partition plate, the inlet is arranged on the lower side of the partition plate, and circular holes are uniformly arranged on the upper surface and the lower surface of the partition plate.

[0025] A temperature sensor is arranged between the filter air chamber and the electrochemical sensor, and the temperature sensor is used to detect the temperature information of the gas sample sprayed from the capillary holes.

[0026] A humidity sensor is arranged between the filter air chamber and the electrochemical sensor, and is used to detect the humidity information of the gas sample sprayed from the capillary hole.

[0027] The installation plate is made of heat insulation material.

[0028] The circuit board is arranged above the installation plate, and the electrochemical sensor is electrically connected to the circuit board.

[0029] Compared with the prior art, in the electrochemical sensor assembly structure for the micro air station, the filter air chamber is arranged inside the heat preservation shell and below the electrochemical sensor. The filter air chamber is a structure with a hollow cavity, and an inlet is arranged on the left side or the right side. The upper surface of the filter air chamber is uniformly provided with protrusions, and the end of each protrusion is provided with a capillary hole. The capillary hole is opposite to the electrode of the electrochemical sensor. The gas sample enters the cavity from the inlet and is sprayed from the capillary hole to contact the electrode of the electrochemical sensor. The contact between the electrode of the electrochemical sensor and the gas sample through the filter air chamber can maximize the simulation of the real environment of the electrochemical sensor for measuring the measured gas, thereby greatly improving the measurement accuracy.

[0030] The present application will become more apparent from the following description in conjunction with the accompanying drawings, which are intended to explain embodiments of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 FIG. 1 shows a cross-sectional view of an embodiment of the electrochemical sensor assembly structure for the micro air station.

[0032] Figure 2 FIG. 4 shows a cross-sectional structure schematic diagram of the filter air chamber.

[0033] Figure 3 FIG. 5 shows a schematic diagram of the upper surface of the filter air chamber. DETAILED DESCRIPTION

[0034] First, the target substances that can be monitored by the micro air station generally include: standard pollutants ozone (O3), nitrogen dioxide (NO2), nitrogen oxides (NOx), carbon monoxide (CO), carbon dioxide (CO2), sulfur dioxide (SO2), etc. x) carbon monoxide (CO), sulfur dioxide (SO2), particulate matter (PM10, PM2.5); some other pollutants of particular concern: volatile organic compounds (VOC), hydrogen sulfide (H2S), carbon dioxide (CO2), etc.; and noise, temperature, humidity, wind speed, wind direction, air pressure, etc. In the present invention, the micro air station mainly monitors the concentration of target substances accurately through electrochemical sensors.

[0035] Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings in which: Figure 1 Fig. 1 shows a cross-sectional view of one embodiment of an electrochemical sensor assembly structure for a micro air station.

[0036] With reference to Figure 1 , the embodiments of the present invention disclose an electrochemical sensor assembly structure 100 for a micro air station, comprising an electrochemical sensor 1, further comprising:

[0037] a temperature control base 2, the temperature control base 2 comprising a Peltier module 21 and a heat conduction module 22, the heat conduction module 22 having a cavity formed on its upper surface, the Peltier module 21 being arranged inside the cavity, the back of the Peltier module 21 being in close contact with the heat conduction module 22;

[0038] It should be noted that the Peltier module 21 can be made to work in a cooling state or a heating state by changing the polarity of the electrodes loaded thereon, so that one Peltier module can achieve cooling or heating, making the temperature control structure of the device simple and very convenient to maintain.

[0039] The back of the Peltier module 21 and the heat conduction module 22 can be coated with a heat-conducting silicone grease to ensure the heat conduction performance of the Peltier module 21 and the heat conduction module 22.

[0040] By way of example, the ideal working environment of an electrochemical sensor should be 20°C. Considering that the Peltier module 21 has a certain delay when cooling or heating, the voltage applied to generate cold (heat) will have a certain delay, so if the working time of the Peltier module 21 is directly controlled, it is difficult to accurately control the temperature. Therefore, the voltage applied to the Peltier module 21 can be controlled by changing the duty cycle of the pwm square wave, and the temperature of the internal environment of the Peltier module 21 and the gas sample in the filter gas chamber can be accurately controlled.

[0041] With reference to Figure 1 , 2 and 3, wherein, Figure 2 Fig. 4 shows a cross-sectional structure diagram of a filter gas chamber, Figure 3The diagram shown is a schematic of the upper surface of the filter compartment.

[0042] The heat-insulating outer shell 3 is connected to the temperature control base 2, and the electrochemical sensor 1 is disposed inside the heat-insulating outer shell 3; in one embodiment, reference Figure 1 The heat insulation shell 3 and the temperature control base 2 are connected by threads or snaps, and the connection between the heat insulation shell 3 and the temperature control base 2 is a detachable connection. When the two are connected, they need to achieve an airtight connection to prevent air leakage, so as to ensure the purpose of accurate flow rate calculation and accurate calculation of the concentration value of the substance to be measured in the gas sample.

[0043] refer to Figure 2 and 3 The filter gas chamber 4 is located inside the thermal insulation shell 3 and below the electrochemical sensor 1. The filter gas chamber 4 has a hollow interior forming a cavity 41, and has an inlet 42 on the left or right side (in this embodiment, as shown in the figure, the inlet is located in the appendix of the specification). Figure 1 On the left side), the upper surface of the filter gas chamber 4 is uniformly provided with protrusions 43, and each of the protrusions 43 has a capillary hole 44 at its end. The capillary hole 44 is directly opposite the electrode of the electrochemical sensor 1. The gas sample enters the cavity 41 from the inlet 42 and is ejected from the capillary hole 44, thus contacting the electrode of the electrochemical sensor 1.

[0044] It should be noted that the upper surface of the filter chamber 4 is uniformly provided with the protrusions 43, and each protrusion 43 has a capillary pore 44 at its end. The function of the capillary pore 44 is to eject the gas sample in the filter chamber 4. This arrangement is to better reduce the pulsation of the gas sample and filter it. The gas sample coming out of the capillary pore 44 receives rectification and filtering to the maximum extent and can be evenly distributed. As long as there are enough capillary pores 44 and the pore diameter of the capillary pores 44 is small enough, it can simulate the real environment gas to the maximum extent, so that the gas sample coming out of the capillary pore 41 can contact the electrode of the electrochemical sensor 1 like the real environment gas, thereby effectively improving the accuracy of the electrochemical sensor 1 in measuring the concentration of the analyte in the gas sample.

[0045] It should also be noted that the gas sample entering the filter chamber 4 has already undergone a dehydration step to remove water. In order to enable the electrodes of the electrochemical sensor 1 to make faster and better contact with the gas sample coming out of the capillary 44, the filter of the electrochemical sensor 1 can be removed in this invention.

[0046] It is also necessary to point out that in the present embodiment, the interior of each protrusion 43 actually forms a conical small cavity, and after the gas sample is rectified and filtered at the cavity 41, each of the conical small cavities actually further plays a role of rectifying and filtering. Therefore, the plurality of uniformly arranged protrusions 43 form an array of conical small cavities, greatly improving the rectifying and filtering effect of the present application.

[0047] It is also necessary to point out that in one embodiment, the filter gas chamber 4 has a capillary hole 44 directly formed on the upper surface thereof, and the capillary hole 44 functions to spray the gas sample in the filter gas chamber 4. In the present embodiment, there is no array of conical small cavities, and the rectifying and filtering effect of the present embodiment is not as good as that of the previous embodiment.

[0048] It is necessary to point out that in one embodiment, the filter gas chamber 4 has a structure with an open lower side, and the gas sample enters the lower side of the filter gas chamber 4 from the inlet 42. At this time, since the temperature control base 2 is provided with a Peltier module 21, the gas sample entering from the inlet 42 can be temperature-controlled by the Peltier module 21. For example, in winter, the gas sample can be low in temperature and needs to be warmed up; in summer, the gas sample can be high in temperature and needs to be cooled down, so that the temperature of the gas sample is suitable for the temperature range for detection by the electrochemical sensor 1. Therefore, in the present embodiment, referring to Figure 2 , the filter gas chamber 4 has a structure with an open side, i.e., an open end 46, and the other side has a plurality of uniformly arranged protrusions 43 and capillary holes 44. The filter gas chamber 4 cooperates with the temperature control base 2 to close the open end 46.

[0049] In one embodiment, referring to Figure 1 , the temperature control base 2 and the heat-insulating shell 3 are connected to each other in a vacuum structure 5. The purpose of such a structure is to minimize heat conduction, and the vacuum structure is a structure with extremely low thermal conductivity.

[0050] In one embodiment, referring to Figure 1 , the heat-insulating shell 3 includes a plastic shell and glass fiber cotton filled in the plastic shell. The glass fiber cotton is safe and has a low heat transfer rate, which helps to reduce heat conduction between the space in the heat-insulating shell 3 and the outside.

[0051] In one embodiment, referring to Figure 1 , the heat-conducting module 22 is an aluminum-based heat dissipation fin. In order to improve the heat conduction performance of the heat-conducting module 22, a convection fan can also be arranged on the heat-conducting module 22.

[0052] In one embodiment, referring to Figure 1, the gas sample is dehydrated by a dehydrating device before entering the filter gas chamber 4. Since humidity is a major factor affecting the service life of the electrochemical sensor 1, the gas sample needs to be dehydrated before being detected by the electrochemical sensor 1.

[0053] In one embodiment, referring to Figure 1 , the inside of the filter gas chamber 4 is further provided with a partition plate 45, the inlet 42 is arranged on the lower side of the partition plate 45, and the upper surface and the lower surface of the partition plate 45 are uniformly provided with circular holes (not shown in the figure). By arranging the partition plate 45 in the filter gas chamber 4, and uniformly arranging the circular holes on the partition plate 45, when the gas sample enters the lower side of the partition plate 45, it will be dispersed to the upper side of the partition plate 45 through the circular holes. Therefore, since the gas sample is in a flowing state under the driving of the air pump, the airflow pulsation generated by the air pump is subjected to first-order rectification filtering under the action of the circular holes of the partition plate 45, which greatly reduces the airflow pulsation of the gas sample and helps to improve the accuracy of the detection of the gas sample by the electrochemical sensor. That is, the protrusion 43 and the capillary hole 44 are the second-order rectification filtering of the gas sample.

[0054] In one embodiment, a temperature sensor (not shown in the figure) is arranged between the filter gas chamber 4 and the electrochemical sensor 1, and the temperature sensor is used to detect the temperature information of the gas sample sprayed from the capillary hole 44. Therefore, the refrigeration power or the heating power of the Peltier module 21 is adjusted in time according to the temperature information detected by the temperature sensor, so that the electrochemical sensor 1 works in an optimal temperature state, thereby effectively improving the accuracy of the detection of the electrochemical sensor.

[0055] In one embodiment, a humidity sensor (not shown in the figure) is arranged between the filter gas chamber 4 and the electrochemical sensor 1, and the humidity sensor is used to detect the humidity information of the gas sample sprayed from the capillary hole 44. The humidity of the gas sprayed from the capillary hole 44 should not exceed a set value (for example, relative humidity 60%RH). If the set value is exceeded, it means that the dehydrating function of the dehydrating device cannot achieve the application dehydrating effect, and the dehydrating device needs to be maintained.

[0056] In one embodiment, referring to Figure 1 , the inside of the heat preservation shell 3 is provided with a mounting plate 6, and the electrochemical sensor 1 is mounted on the mounting plate 6. The mounting plate 6 is a mounting plate made of heat insulation material. Through the mounting plate 6, the installation of the electrochemical sensor 1 can be facilitated.

[0057] In one embodiment, referring to Figure 1The heat preservation shell is internally provided with a circuit board 7, the circuit board 7 is arranged above the mounting plate 6, and the electrochemical sensor 1 is electrically connected with the circuit board 7. The circuit board 7 can be a circuit board for controlling power-on or power-off of the electrochemical sensor 1, in addition, the circuit board 7 can also be installed with an embedded control system for controlling the working state of the Peltier module 21, a temperature sensor, a humidity sensor and other electronic components.

[0058] The above only discloses preferred embodiments of the present application, and of course cannot limit the scope of the patent rights of the present application, therefore, equivalent changes made in the patent application scope of the present application still belong to the scope covered by the present application.

Claims

1. An electrochemical sensor assembly for a micro air station, comprising an electrochemical sensor, characterized in that, Also include: The temperature control base includes a Peltier module and a heat conduction module, and the upper surface of the heat conduction module is provided with a recess, and the Peltier module is arranged in the recess, and the back of the Peltier module is in close contact with the heat conduction module; The temperature control base and the heat preservation shell are connected to each other and are provided with a vacuum structure; The filter gas chamber is provided inside the heat preservation shell and below the electrochemical sensor, and the filter gas chamber is provided with an inlet on the left side or the right side, and the upper surface of the filter gas chamber is uniformly provided with a plurality of protrusions, and the end of each protrusion is provided with a capillary hole, and the capillary hole is opposite to the electrode of the electrochemical sensor, and the filter gas chamber is further provided with a partition plate, and the inlet is arranged below the partition plate, and the upper surface and the lower surface of the partition plate are uniformly provided with a plurality of circular holes, and the gas sample enters the cavity from the inlet and is sprayed from the capillary hole to contact the electrode of the electrochemical sensor.

2. The electrochemical sensor assembly for a micro air station of claim 1, wherein, The heat preservation shell includes a plastic shell and glass fiber cotton filled in the plastic shell.

3. The electrochemical sensor assembly for a micro air station of claim 1, wherein, The heat conduction module is an aluminum base heat dissipation fin.

4. The electrochemical sensor assembly for a micro air station of claim 1, wherein, The gas sample is subjected to a water removal device before entering the filter gas chamber.

5. The electrochemical sensor assembly for a micro air station of claim 1, wherein, A temperature sensor is arranged between the filter gas chamber and the electrochemical sensor, and the temperature sensor is used to detect the temperature information of the gas sample sprayed from the capillary hole. A humidity sensor is arranged between the filter gas chamber and the electrochemical sensor, and the humidity sensor is used to detect the humidity information of the gas sample sprayed from the capillary hole.

6. The electrochemical sensor assembly for a micro air station of claim 1, wherein, The heat preservation shell is provided with a mounting plate, and the electrochemical sensor is mounted on the mounting plate, and the mounting plate is made of heat insulation material.

7. The electrochemical sensor assembly for a micro air station of claim 6, wherein, The heat preservation shell is provided with a circuit board, and the circuit board is arranged above the mounting plate, and the electrochemical sensor and the circuit board are electrically connected.

Images