Waterproof, breathable and differential calibration packaging device and method for gas sensor

Abstract

The invention discloses a waterproof, breathable and differential calibration packaging device and method for a gas sensor, and the device is characterized in that the top of a sensor housing is provided with a waterproof and breathable film, so that tested gas can rapidly pass through the waterproof and breathable film, and the speed of water vapor entering a test space is reduced; the fan drives the gas to flow between the test space and the absorption space, so that water vapor or water vapor / tested gas entering the test space can be adsorbed. If the absorption space is filled with the water absorption material, the water vapor in the test space is removed by combining the water vapor slow permeation effect of the waterproof breathable film and the air flow driving function of the fan. If the absorption space is filled with a water absorption material and a selective filtering material, intermittent flow of gas in the test space is realized through starting and stopping of the fan, a dynamic response signal of the gas sensor is obtained, and zero calibration of the gas sensor is realized by utilizing an output signal when the fan is started; and the anti-interference detection of the gas sensor is realized by utilizing the output signal difference in the on and off states of the fan.

Description

Technical Field

[0001] The invention belongs to gas detection technology, and in particular relates to a gas sensor waterproof and breathable and differential calibration packaging device and method. Background Art

[0002] Gas detection has important application prospects in the fields of air pollution monitoring, breath health diagnosis, industrial safety, production quality control, national defense and military. Metal oxide gas sensors have an important position in the field of gas detection and have been widely used due to their high sensitivity, fast response speed, simple production and low cost.

[0003] However, most metal oxide gas sensors have broad-spectrum response characteristics, and their sensitive mechanism makes it difficult for them to respond to only a single gas. In actual complex working environments, the presence of multi-component gases directly affects the reliability of target gas type identification and content detection. There is water vapor interference in high humidity environments. Whether it is water physically adsorbed or chemically adsorbed on the surface of gas-sensitive materials, it will affect its physical and chemical properties, thereby changing the sensor's baseline resistance and gas-sensitive reaction activity, and thus affecting the performance of the sensor. Therefore, improving the anti-interference performance of metal oxide gas sensors and eliminating the impact of complex environments on sensor performance to achieve reliable detection of target gases have become technical challenges faced by the application of metal oxide gas sensors.

[0004] The most direct strategy to improve the anti-interference performance of metal oxide gas sensors is to improve the performance of sensitive materials. Researchers have enhanced the sensor's response to specific target molecules and achieved "one-to-one" selective gas detection by optimizing the sensor's material system selection, morphology and size regulation, doping component regulation, and surface modification. However, due to the broad-spectrum effect of metal oxide sensitive materials, improvements based on the development, doping, and modification of sensitive materials have limitations in improving sensor selectivity and are difficult to meet the detection needs in complex multi-component environments.

[0005] Physically blocking the contact between water vapor and gas-sensitive materials is a direct and effective means to inhibit the influence of water molecules on sensor performance. Most of the methods currently used rely on waterproof and breathable membranes to reduce the humidity of the measured gas. The commonly used polydimethylsiloxane (PDMS) membrane not only has a hydrophobic surface to prevent the entry of liquid water, but also the principle of like dissolves like can effectively reduce the penetration rate of water molecules. Summary of the invention

[0006] In order to solve the problem that the waterproof and breathable membrane described in the background technology cannot permanently reduce the water vapor content of the measured gas inside the gas sensor packaging structure and cannot eliminate the interference of multi-component gases, the present invention proposes a gas sensor waterproof and breathable and differential calibration packaging method.

[0007] Technical solution adopted by the invention:

[0008] A gas sensor waterproof and breathable and differential calibration packaging device, comprising a sensor housing, an adsorption housing, a gas path, a gas sensor, a humidity sensor, a waterproof and breathable membrane, a filter and a fan;

[0009] The inner space of the sensor housing constitutes a test space, a gas sensor and a humidity sensor are arranged at the bottom of the test space, and a waterproof and breathable membrane is arranged at the top of the test space;

[0010] The inner space of the adsorption shell constitutes an absorption space, a fan is arranged in the middle of the absorption space, and both sides of the fan in the absorption space are filled with water-absorbing materials or selective filtering materials;

[0011] The test space and the absorption space are connected through an air path, and the test space and the absorption space are isolated by a filter.

[0012] In the above technical solution, the water-absorbing material is a material that only absorbs water vapor but not gas.

[0013] In the above technical solution, the water absorbing material is preferably silica gel.

[0014] In the above technical solution, the selective filtering material is a material that has an adsorption effect on the gas to be measured but has no adsorption effect on other interfering gases.

[0015] In the above technical solution, the filter screen is a stainless steel filter screen or a microporous filter membrane.

[0016] In the above technical solution, the material of the waterproof and breathable membrane is polydimethylsiloxane.

[0017] A gas sensor waterproof, breathable and differential calibration packaging method comprises the following steps:

[0018] (1) If the absorption space is filled with water-absorbing materials, the water molecules in the test space can be removed by combining the slow water vapor penetration of the waterproof breathable membrane and the air flow driving function of the fan, thereby improving the humidity resistance of the gas sensor.

[0019] (2) If the absorption space is filled with water-absorbing materials and selective filtering materials, the intermittent flow of gas in the test space is achieved by turning the fan on and off, and the dynamic response signal of the gas sensor is obtained; the output signal when the fan is turned on is used to realize the zero point calibration of the gas sensor, and the anti-interference detection of the gas sensor is realized by using the difference of the output signal when the fan is turned on and off.

[0020] Beneficial effects:

[0021] Compared with the existing gas sensor waterproof and breathable packaging method, the gas sensor waterproof and breathable and differential calibration packaging method proposed in the present invention relies on a waterproof and breathable membrane to prevent the entry of liquid water vapor, and relies on internally filled water-absorbing materials or water-absorbing materials / selective filter materials and fan-driven gas flow to eliminate the influence of internally accumulated water molecules and multi-component interfering gases.

[0022] When the absorption space is filled with water-absorbing materials, the slow water vapor penetration of the waterproof breathable membrane and the airflow driving function of the fan are combined to complete the efficient removal of water vapor in the test space, thereby improving the humidity resistance of the gas sensor.

[0023] When the absorption space is filled with water-absorbing materials and selective filtering materials, the intermittent flow of gas in the test space is achieved by turning the fan on and off, thereby obtaining a dynamic response signal of the gas sensor. The zero-point calibration of the gas sensor can be achieved using the output signal when the fan is turned on, and the anti-interference detection of the gas sensor can be achieved using the difference in the output signal when the fan is turned on and off. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 Schematic diagram of the waterproof and breathable packaging structure of metal oxide gas sensors.

[0025] Figure 2 Schematic diagram of the differential calibration packaging structure of the metal oxide gas sensor.

[0026] Figure 3 Functional schematic diagram of the waterproof and breathable packaging method for metal oxide gas sensors.

[0027] Figure 4 Workflow diagram of the packaging method for differential calibration of metal oxide gas sensors.

[0028] Figure 5 Differential calibration of the sensor output signal of the packaging method for metal oxide gas sensors.

[0029] Among them, 1 is a gas sensor, 2 is a waterproof breathable membrane, 3 is a sensor housing, 4 is an adsorption housing, 5 is an air path, 6 is a water-absorbing material, 7 is a filter, 8 is a humidity sensor, 9 is a selective filtering material, 10 is a fan, 301 is a test space, and 401 is an absorption space. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0031] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0032] Example

[0033] Figure 1 The figure is a schematic diagram of the waterproof and breathable packaging structure of a metal oxide gas sensor. The structure includes a sensor housing 3 and an adsorption housing 4 connected to the sensor housing 3 through an air path 5. A gas sensor 1 and a humidity sensor 8 are mounted on the bottom of the sensor housing 3, and a waterproof and breathable membrane 2 is installed on the top to form a test space 301; the internal space of the adsorption housing 4 is an absorption space 401, which is filled with a water-absorbing material 6, and a fan 10 is installed in the middle; the test space 301 and the absorption space 401 are separated by a filter 7. The air path 5 connects the sensor test space 301 and the absorption space 401, and the fan 10 drives the gas to flow between the test space 301-air path 5-absorption space 401. The waterproof and breathable membrane 2 is polydimethylsiloxane PDMS, the water-absorbing material 6 is a material such as silica gel that only absorbs water vapor but not gas, and the filter 7 is a stainless steel filter or a microporous filter membrane.

[0034] Figure 2 The schematic diagram of the differential calibration packaging structure of the metal oxide gas sensor is shown in FIG. The structure includes a sensor housing 3 and an adsorption housing 4 connected thereto through an air path 5. A gas sensor 1 and a humidity sensor 8 are mounted on the bottom of the sensor housing 3, and a waterproof breathable membrane 2 is mounted on the top to form a test space 301; the internal space of the adsorption housing 4 is an absorption space 401, which is filled with a water-absorbing material 6 and a selective filtering material 9, and a fan 10 is installed in the middle; the test space 301 and the absorption space 401 are separated by a filter 7. The air path 5 connects the sensor test space 301 and the absorption space 401, and the fan 10 drives the gas to flow between the test space 301-air path 5-absorption space 401. The waterproof breathable membrane 2 is polydimethylsiloxane PDMS, the water-absorbing material 6 is a material such as silica gel that only absorbs water vapor but not gas, the selective filtering material 8 is a material that has an adsorption effect on the gas to be measured but has no adsorption effect on the multi-component interfering gas, and the filter 7 is a stainless steel filter or a microporous filter membrane.

[0035] Figure 3The functional schematic diagram of the waterproof and breathable packaging method for metal oxide gas sensors. The working environment of the gas sensor contains the gas to be measured, interfering gas and water vapor. The PDMS waterproof and breathable membrane 2 has a hydrophobic surface to prevent liquid water from entering the test space 301, but due to the principle of like dissolves like, water molecules can slowly penetrate into the test space 301, and at the same time, the gas to be measured and the interfering gas can quickly enter the test space 301 through the waterproof and breathable membrane 2. The absorption space 401 is filled with water-absorbing materials 6 such as silica gel, and the fan 10 drives the gas to flow between the test space 301-gas path 5-absorption space 401. Since the speed at which water molecules pass through the semi-permeable membrane is slow, most of the water molecules will be adsorbed by the water-absorbing material as the internal gas flows, and the water molecule content in the test space 301 is very small. Therefore, this method can significantly improve the moisture resistance of the gas sensor.

[0036] Figure 4 The flowchart of the differential calibration packaging method for metal oxide gas sensors is shown in FIG. The absorption space 401 is filled with water-absorbing material 6 and selective filter material 9, and the intermittent flow of gas in the test space 301 is achieved by turning on and off the fan 10. The working environment of the gas sensor contains the measured gas, interfering gas and water vapor. The PDMS waterproof breathable membrane 2 allows water molecules to slowly penetrate into the test space 301, while the measured gas and interfering gas can quickly enter the test space 301 through the waterproof breathable membrane 2.

[0037] Figure 4 (a) is the initial state of the fan being turned on. Since the speed at which water molecules pass through the semipermeable membrane is slow, most of the water molecules will be absorbed by the water-absorbing material as the internal gas flows, and the content of water molecules in the test space 301 is extremely small. At the same time, the water-absorbing material 6 such as silica gel and the selective filtering material 9 filled in the absorption space 401 can quickly absorb the gas to be tested that enters the test space, and the content of the gas to be tested in the test space 301 is extremely small. In this state, the test space is basically filled with interfering gas.

[0038] Figure 4 (b) is the fan off state. The water molecule content in the test space 301 will increase with time, but because the water molecules pass through the semipermeable membrane slowly, the water molecule concentration in the test space does not change much in a short time. The gas to be tested and the interfering gas can quickly pass through the waterproof breathable membrane into the test space and reach equilibrium with the concentration in the environment. In this state, the test space is basically filled with interfering gas and test gas.

[0039] Figure 4(c) is the state where the fan is turned on again. Most of the water molecules will be absorbed by the water-absorbing material as the internal gas flows, and the content of water molecules in the test space 301 is extremely small. At the same time, the water-absorbing material 6 such as silica gel and the selective filter material 9 filled in the absorption space 401 can quickly absorb the gas to be tested that enters the test space, and the content of the gas to be tested in the test space 301 is extremely small. In this state, the test space is restored to basically being filled with interfering gas.

[0040] Figure 4 Middle (a) to Figure 4 (b) to Figure 4 The fan on-off-on process in (c) is a working cycle, and the gases that the sensor contacts are interference gas, interference gas, test gas, and interference gas. Figure 4 The output signal obtained in case (a) can realize the zero point calibration of the gas sensor. Figure 4 (b) and Figure 4 The output signal difference in (c) can realize anti-interference detection of gas sensors.

[0041] Figure 5 It is the sensor output signal of the differential calibration packaging method of the metal oxide gas sensor. Among them, S1, S2, and S3 correspond to Figure 4 Middle (a), Figure 4 (b) and Figure 4 There are three states in (c). States S1 and S2 are switched by turning off the fan, and states S2 and S3 are switched by turning on the fan. Figure 4 (a) and Figure 4 The output signal obtained in case (c) is the starting resistance, state Figure 4 The output signal obtained in case (b) is the test resistance. The initial resistance only contains the resistance value of the gas sensor in the presence of interfering gas, while the test resistance contains the resistance value of the gas sensor under the combined action of the interfering gas and the test gas. Therefore, the initial resistance of the sensor can be considered as the zero point value under the working environment, and the difference between the test resistance and the initial resistance is the response value of the sensor to the measured gas after zero point calibration. This method realizes the zero point calibration of the gas sensor in a complex gas environment and the differential detection of the measured gas, effectively improving the reliability of gas detection.

[0042] The above description is only a specific implementation of the present application, so that those skilled in the art can understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest range consistent with the principles and novel features applied for herein.

Claims

1. A gas sensor waterproof, breathable and differential calibration packaging device, characterized in that: It includes a sensor housing, an adsorption housing, an air passage, a gas sensor, a humidity sensor, a waterproof and breathable membrane, a filter and a fan; The inner space of the sensor housing constitutes a test space, a gas sensor and a humidity sensor are arranged at the bottom of the test space, and a waterproof and breathable membrane is arranged at the top of the test space; The inner space of the adsorption shell constitutes an absorption space, a fan is arranged in the middle of the absorption space, and both sides of the fan in the absorption space are filled with water-absorbing materials or selective filtering materials; The test space and the absorption space are connected through an air path, and the test space and the absorption space are isolated by a filter.

2. A gas sensor waterproof, breathable and differential calibration packaging device according to claim 1, characterized in that: The water-absorbing material is a material that only absorbs water vapor but does not absorb gas.

3. A gas sensor waterproof, breathable and differential calibration packaging device according to claim 2, characterized in that: The water absorbing material is silica gel.

4. A gas sensor waterproof, breathable and differential calibration packaging device according to claim 1, characterized in that: The selective filtering material is a material that has an adsorption effect on the gas to be measured but has no adsorption effect on other interfering gases.

5. A gas sensor waterproof, breathable and differential calibration packaging device according to claim 1, characterized in that: The filter screen is a stainless steel filter screen or a microporous filter membrane.

6. A gas sensor waterproof, breathable and differential calibration packaging device according to claim 1, characterized in that: The material of the waterproof and breathable membrane is polydimethylsiloxane.

7. A gas sensor waterproof, breathable and differential calibration packaging method, characterized in that: (1) If the absorption space is filled with water-absorbing materials, the water molecules in the test space can be removed by combining the slow water vapor penetration of the waterproof breathable membrane and the air flow driving function of the fan, thereby improving the humidity resistance of the gas sensor; (2) If the absorption space is filled with water-absorbing materials and selective filtering materials, the intermittent flow of gas in the test space is achieved by turning the fan on and off, and the dynamic response signal of the gas sensor is obtained; the output signal when the fan is turned on is used to realize the zero point calibration of the gas sensor, and the anti-interference detection of the gas sensor is realized by using the difference of the output signal when the fan is turned on and off.

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