A gas sensor waterproof and air-permeable and differential calibration packaging device and method

Abstract

The application discloses a kind of gas sensor waterproof and venting and differential calibration packaging device and method, sensor shell top is equipped with waterproof and venting film, can make the measured gas quickly pass and reduce the speed of water vapor into test space;Fan drives gas to flow between test space and absorption space, can be into test space water vapor or water vapor / measured gas adsorption.If absorption space is filled with water-absorbing material, combined with the slow penetration of water vapor of waterproof and venting film and the fan airflow driving function completes the removal of water vapor in test space.If absorption space is filled with water-absorbing material and selective filter material, the intermittent flow of gas in test space is realized by the opening and closing of fan, the dynamic response signal of gas sensor is obtained, the zero point calibration of gas sensor is realized using the output signal when fan is opened, and the anti-interference detection of gas sensor is realized using the differential output signal under the opening and closing state of fan.

Description

Technical Field

[0001] This invention pertains to gas detection technology, specifically relating to a waterproof and breathable gas sensor and a differential calibration packaging device and method. Background Technology

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

[0003] However, most metal oxide gas sensors possess broad-spectrum response characteristics, and their sensing mechanism makes it difficult for them to respond to only a single gas. In complex real-world working environments, the presence of multi-component gases directly affects the reliability of target gas identification and concentration detection. High-humidity environments present water vapor interference; whether physically or chemically adsorbed onto the surface of the gas-sensitive material, water affects its physicochemical properties, thereby altering the sensor's baseline resistance and gas-sensing reactivity, ultimately impacting sensor performance. Therefore, improving the anti-interference performance of metal oxide gas sensors and eliminating the influence of complex environments on sensor performance to achieve reliable target gas detection has become a key technical challenge in the application of metal oxide gas sensors.

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

[0005] Physically blocking the contact between water vapor and gas-sensitive materials is a direct and effective means of suppressing the influence of water molecules on sensor performance. Currently, most methods rely on waterproof and breathable membranes to reduce the humidity of the gas being measured. Commonly used polydimethylsiloxane (PDMS) membranes not only have a hydrophobic surface to prevent the entry of liquid water, but also effectively reduce the permeation rate of water molecules due to the principle of "like dissolves like". Summary of the Invention

[0006] To address the issues raised in the background art regarding the inability of waterproof and breathable membranes to effectively reduce the moisture content of the gas being measured inside the gas sensor encapsulation structure and to eliminate interference from multi-component gases, this invention proposes a waterproof, breathable, and differential calibration encapsulation method for gas sensors.

[0007] The technical solution adopted in the invention:

[0008] A waterproof and breathable gas sensor and differential calibration packaging device includes a sensor housing, an adsorption housing, a gas passage, a gas sensor, a humidity sensor, a waterproof and breathable membrane, a filter, and a fan.

[0009] The internal space of the sensor housing constitutes a test space. A gas sensor and a humidity sensor are installed at the bottom of the test space, and a waterproof and breathable membrane is installed at the top of the test space.

[0010] The internal space of the adsorption shell constitutes an absorption space. A fan is installed in the middle of the absorption space, and water-absorbing material or selective filter material is filled on both sides of the fan in the absorption space.

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

[0012] In the above technical solution, the water-absorbing material is a material that only adsorbs water vapor and does not adsorb gas.

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

[0014] In the above technical solution, the selective filter material is a material that adsorbs the gas being tested but does not adsorb 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 waterproof and breathable gas sensor packaging method for differential calibration includes the following steps:

[0018] (1) If the absorption space is filled with water-absorbing material, the water vapor slowly permeates through the waterproof and breathable membrane, and the airflow driven by the fan completes the removal of water molecules in the test space, thereby improving the humidity resistance of the gas sensor.

[0019] (2) If the absorption space is filled with water-absorbing material and selective filter material, the gas in the test space is intermittently flowed by turning the fan on and off, and the dynamic response signal of the gas sensor is obtained; the zero-point calibration of the gas sensor is achieved by using the output signal when the fan is on, and the anti-interference detection of the gas sensor is achieved by using the output signal difference when the fan is on and off.

[0020] Beneficial effects:

[0021] Compared with existing waterproof and breathable packaging methods for gas sensors, the waterproof and breathable packaging method for gas sensors and differential calibration proposed in this invention relies on a waterproof and breathable membrane to prevent the entry of liquid water vapor, and relies on the internal filling of water-absorbing material or water-absorbing material / selective filter material and fan drive to form gas flow to eliminate the influence of water molecules and multi-component interfering gases accumulated inside.

[0022] When the absorption space is filled with absorbent material, the slow permeation of water vapor through the waterproof and breathable membrane, combined with the airflow driven by the fan, efficiently removes water vapor from the test space, improving the humidity resistance of the gas sensor.

[0023] When the absorption space is filled with absorbent and selective filter materials, the intermittent flow of gas within the test space is achieved by turning the fan on and off, thereby obtaining the dynamic response signal of the gas sensor. The output signal when the fan is on can be used for zero-point calibration of the gas sensor, and the differential output signal between the fan on and off states can be used for anti-interference detection of the gas sensor. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the waterproof and breathable encapsulation structure for a metal oxide gas sensor.

[0025] Figure 2 This is a schematic diagram of the differential calibration packaging structure for a metal oxide gas sensor.

[0026] Figure 3 This is a functional schematic diagram of a waterproof and breathable encapsulation method for metal oxide gas sensors.

[0027] Figure 4 This is a flowchart illustrating the differential calibration packaging method for metal oxide gas sensors.

[0028] Figure 5 The sensor output signal is provided by the differential calibration packaging method for metal oxide gas sensors.

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

[0030] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

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

[0032] Example

[0033] Figure 1 This is a schematic diagram of the waterproof and breathable encapsulation structure of a metal oxide gas sensor. The structure includes a sensor housing 3 and an adsorption housing 4 connected to it via a gas path 5. A gas sensor 1 and a humidity sensor 8 are attached to the bottom of the sensor housing 3, and a waterproof and breathable membrane 2 is installed on the top, forming a test space 301. The internal space of the adsorption housing 4 is an absorption space 401, filled with absorbent material 6, and a fan 10 is installed in the middle. A filter 7 separates the test space 301 and the absorption space 401. The gas 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, the gas path 5, and the absorption space 401. The waterproof and breathable membrane 2 is polydimethylsiloxane (PDMS), the absorbent material 6 is a material such as silica gel that only adsorbs water vapor and not gas, and the filter 7 is a stainless steel filter or a microporous filter membrane.

[0034] Figure 2 This is a schematic diagram of the differential calibration packaging structure of a metal oxide gas sensor. The structure includes a sensor housing 3 and an adsorption housing 4 connected to it via a gas path 5. A gas sensor 1 and a humidity sensor 8 are attached to the bottom of the sensor housing 3, and a waterproof and breathable membrane 2 is installed on the top, forming a test space 301. The internal space of the adsorption housing 4 is an absorption space 401, filled with absorbent material 6 and selective filter material 9, with a fan 10 installed in the middle. A filter screen 7 isolates the test space 301 and the absorption space 401. The gas 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, the gas path 5, and the absorption space 401. The waterproof and breathable membrane 2 is polydimethylsiloxane (PDMS), the absorbent material 6 is a material such as silica gel that only adsorbs water vapor and not gas, the selective filter material 8 is a material that adsorbs the gas being measured but not multi-component interfering gases, and the filter screen 7 is a stainless steel filter screen or a microporous filter membrane.

[0035] Figure 3This is a functional schematic diagram of a waterproof and breathable encapsulation method for a metal oxide gas sensor. The working environment of the gas sensor includes the target gas, interfering gases, and water vapor. The PDMS waterproof and breathable membrane 2 has a hydrophobic surface that prevents liquid water from entering the test space 301. However, due to the principle of "like dissolves like," water molecules can slowly permeate into the test space 301. Simultaneously, the target gas and interfering gases can quickly pass through the waterproof and breathable membrane 2 into the test space 301. The absorption space 401 is filled with a water-absorbing material 6 such as silica gel. A fan 10 drives the gas to flow between the test space 301, the gas path 5, and the absorption space 401. Because water molecules permeate the semi-permeable membrane slowly, most water molecules are adsorbed by the water-absorbing material along with the internal gas flow. The water molecule content in the test space 301 is extremely low. Therefore, this method can significantly improve the moisture resistance of the gas sensor.

[0036] Figure 4 This is a flowchart illustrating the differential calibration packaging method for a metal oxide gas sensor. The absorption space 401 is filled with absorbent material 6 and selective filter material 9. Intermittent gas flow within the test space 301 is achieved by turning the fan 10 on and off. The gas sensor's operating environment contains the target gas, interfering gases, and water vapor. The PDMS waterproof and breathable membrane 2 allows water molecules to slowly permeate into the test space 301, while the target gas and interfering gases can quickly pass through the waterproof and breathable membrane 2 into the test space 301.

[0037] Figure 4 (a) shows the initial fan-on state. Because water molecules pass through the semi-permeable membrane slowly, most water molecules are adsorbed by the absorbent material along with the internal gas flow, resulting in very low water molecule content in test space 301. Simultaneously, the absorbent material 6 (such as silica gel) and selective filter material 9 filling absorption space 401 quickly adsorb the gas to be tested entering the test space, further reducing the gas content in test space 301. In this state, the test space is primarily filled with interfering gases.

[0038] Figure 4 (b) shows the fan off. The water molecule content in test space 301 increases over time, but because water molecules pass through the semi-permeable membrane slowly, the water molecule concentration in the test space does not change significantly in a short period. The test gas and interfering gas can quickly pass through the waterproof and breathable membrane into the test space and reach equilibrium with the concentration in the environment. In this state, the test space is basically composed of interfering gas and test gas.

[0039] Figure 4(c) indicates the fan is turned on again. Most water molecules are adsorbed by the absorbent material along with the internal gas flow, resulting in very low water molecule content in test space 301. Simultaneously, the absorbent material 6 (such as silica gel) and selective filter material 9 filling absorption space 401 quickly adsorb the gas being tested entering the test space, further reducing the gas content in test space 301. In this state, the test space is restored to being primarily filled with interfering gases.

[0040] Figure 4 (a) to Figure 4 From (b) to Figure 4 The fan in (c) cycles on and off, and the gases the sensor comes into contact with are interfering gas, interfering gas, test gas, and interfering gas, respectively. (Status) Figure 4 The output signal obtained in case (a) can be used to perform zero-point calibration of the gas sensor. Figure 4 (b) and Figure 4 The differential output signal in (c) can enable anti-interference detection of the gas sensor.

[0041] Figure 5 This refers to the sensor output signal of the differential calibration packaging method for metal oxide gas sensors. Where S1, S2, and S3 respectively correspond to... Figure 4 (a) Figure 4 (b) and Figure 4 The three states in (c) are as follows: 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 In case (c), the output signal obtained is the initial resistance, and the state is... Figure 4 In case (b), the output signal obtained 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 interfering and test gases. Therefore, the sensor's initial resistance 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 sensor's response value to the measured gas after zero-point calibration. This method realizes zero-point calibration of the gas sensor and differential detection of the measured gas in complex gas environments, effectively improving the reliability of gas detection.

[0042] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A gas sensor waterproof, air-permeable and differential calibration packaging device, characterized by: The sensor shell, the adsorption shell, the through air path, the gas sensor, the humidity sensor, the waterproof and air-permeable membrane, the filter screen and the fan are included. The internal space of the sensor shell constitutes a test space, the bottom of the test space is provided with the gas sensor and the humidity sensor, and the top of the test space is provided with the waterproof and air-permeable membrane. The internal space of the adsorption shell constitutes an absorption space, the middle of the absorption space is provided with the fan, and the two sides of the fan in the absorption space are filled with the water-absorbing material or the selective filtering material; the fan drives the gas to flow between the test space and the absorption space, and the selective filtering material is a material that has an adsorption effect on the measured gas and has no adsorption effect on other interference gases. The test space and the absorption space are connected in communication through the through air path, and the test space and the absorption space are isolated by the filter screen.

2. The waterproof, air-permeable, and differential calibration packaging device for a gas sensor according to claim 1, characterized in that: The water-absorbing material is a material that only adsorbs water vapor and does not adsorb gas.

3. The waterproof, air-permeable, and differential calibration packaging device for a gas sensor according to claim 2, characterized in that: The water-absorbing material is silica gel.

4. The waterproof, air-permeable, and differential calibration packaging device for a gas sensor according to claim 1, characterized in that: The filter screen is a stainless steel filter screen or a microporous filter membrane.

5. The waterproof, air-permeable, and differential calibration packaging device for a gas sensor according to claim 1, characterized in that: The material of the waterproof and air-permeable membrane is polydimethylsiloxane.

6. A method for waterproof and differential calibration packaging of a gas sensor, characterized in that: The waterproof and air-permeable and differential calibration packaging device for the gas sensor is adopted, (1) if the absorption space is filled with the water-absorbing material, the water molecules in the test space are removed by the slow water vapor penetration of the waterproof and air-permeable membrane and the air flow driving function of the fan, and the humidity resistance of the gas sensor is improved; (2) if the absorption space is filled with the water-absorbing material and the selective filtering material, the intermittent flow of the gas in the test space is realized by the opening and closing of the fan, and the dynamic response signal of the gas sensor is obtained; the zero point calibration of the gas sensor is realized by the output signal when the fan is turned on, and the anti-interference detection of the gas sensor is realized by the differential of the output signals in the opening and closing states of the fan. When the fan is turned on, the selective filtering material in the absorption space adsorbs the measured gas, so that the test space is filled with the interference gas; when the fan is turned off, the test space contains the interference gas and the measured gas.

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