Liquid-phase water interference resistant humidity sensor based on atomic layer deposition technology

Abstract

The liquid-phase water interference-resistant humidity sensor based on the atomic layer deposition technology comprises a humidity sensing unit and is characterized by further comprising a closed shell, the shell is provided with an inner surface and an outer surface, the shell is made of a micropore channel material, the micropore channel penetrates through the inner surface and the outer surface of the shell, and the humidity sensing unit is arranged in the shell. Gas can pass through the inside and the outside of the shell; the device further comprises a protective cover, a closed shell, a motor, a fan and a bottom plate, the protective cover and the shell are the same in shape, and the size of the protective cover is larger than that of the shell, so that the protective cover can cover the shell; the motor, the fan, the humidity sensing unit and the shell are all arranged in the protective cover in a covering mode to form a whole, the whole is installed on the bottom plate, and a gap is reserved between the whole and the bottom plate and used for enabling ambient air to enter the shell of the humidity sensor.

Description

Technical Field

[0001] The present invention is a further improvement of our prior application CN2024111982731, and relates to a humidity sensor suitable for use in outdoor environments, specifically to a humidity sensor that is resistant to liquid phase water interference based on atomic layer deposition technology, and its IPC classification number is G01N27 / 00. Background Art

[0002] When the humidity sensor is used outdoors, it will inevitably encounter liquid water such as rain and fog droplets, which will have many adverse effects. Liquid water droplets may have a variety of adverse effects on the humidity sensor. For details, please refer to the background technology introduction section of our prior application CN2024111982731.

[0003] In the above-mentioned prior application, the use of a hydrophobic porous shell resists the harmful effects of liquid water droplets on the humidity sensor, and the micron-sized micropores ensure that water molecules in the ambient air can freely penetrate into the humidity sensor. The closed shell reduces the rate at which heat from the heating element is dissipated to the external environment, thereby reducing the overall power consumption of the sensor.

[0004] However, it is necessary to make further improvements to the humidity sensor, namely: (1) Humidity sensors with closed housings may indeed face the problem of slow response speed. This is because the design of the housing restricts the flow of air inside and outside the sensor, thereby affecting the gas exchange speed. The following is a detailed explanation: (2) Restricting gas exchange: The working principle of humidity sensors usually relies on the detection of water vapor content in the air. The closed housing may limit the speed at which external air enters the sensor, resulting in a slower gas exchange rate between the sensor and the external environment.

[0005] (3) Impact on sensor response: When the humidity in the environment changes, the humidity sensor needs to respond to these changes quickly enough to provide accurate readings. If the housing restricts air flow, the sensor's internal response to humidity changes will be slower because water vapor molecules take longer to reach the sensor's detection area.

[0006] (4) Accuracy issues: In addition to slower response speed, insufficient gas exchange may also cause inaccurate sensor readings. The sensor may continue to display old humidity data instead of the actual humidity in the current environment.

[0007] The technical problem to be solved by the present invention is: while maintaining the superiority of the humidity sensor in the prior application CN2024111982731, further improving its response speed. Summary of the invention

[0008] The present invention is a further improvement of our prior application CN2024111982731, the contents of which are regarded as part of the present invention. The right to introduce part or all of the contents of the above-mentioned prior application is reserved in the present invention.

[0009] The specific technical solution for achieving the purpose of the present invention is: A humidity sensor based on atomic layer deposition technology and resistant to liquid phase water interference, comprising a humidity sensitive unit, characterized in that: it also comprises a closed shell, the shell having an inner surface and an outer surface, and the shell is made of a microporous channel material, the microporous channel penetrates the inner surface and the outer surface of the shell, so that gas can pass through the inside and outside of the shell; The humidity sensitive unit is sealed in the shell, and the inner surface, outer surface and wall surface of the microporous channel of the shell are covered with a hydrophobic layer material. The microporous channel on the shell is used to block liquid water droplets in the air; the shell is also provided with a wire connection hole for leading the wire connected to the humidity sensitive unit to the external measurement and control circuit, and the wire is sealed through the connection hole.

[0010] It also includes a protective cover, a closed shell, a motor, a fan, and a bottom plate. The protective cover has the same shape as the shell, and the size of the protective cover is larger than the shell, so that the protective cover can cover the shell; the motor, the fan, the humidity sensitive unit, and the shell are all covered and arranged in the protective cover to form a whole, which is installed on the bottom plate as a whole, and a gap is left between the bottom plate so that ambient air can enter the inside of the shell of the humidity sensor; The fan is mounted on the motor, and the humidity sensitive unit is enclosed in the housing and above the fan. The above arrangement enables the fan to accelerate the penetration of ambient air into the housing of the humidity sensor. The flow of gas shortens the response time of the humidity sensor (i.e., the response speed is accelerated), and can quickly respond to changes in ambient air humidity, and avoids interference of liquid water on the humidity sensor, thereby improving measurement accuracy. In the present invention, the diameter of the microporous channel in the shell is between 1 and 100 micrometers. The principle for selecting the diameter of the microporous channel is that its surface tension can prevent rainwater and fog from entering the shell.

[0011] The manufacturing method of the housing comprises the following steps: (1) Material selection: Select a certain proportion of powder materials of inorganic minerals or metal oxides and short fiber materials; these materials will be mixed evenly; (2) Making blanks: Add the mixed powder and fiber materials into a fluid binder to make blanks; the binder helps the materials maintain their shape until they are solidified; (3) Mold forming: Use a mold to make the blank into a shell of a preset shape; this step is to ensure that the shape of the shell meets the design requirements; (4) Drying and shaping: Dry the blank in the mold to remove excess moisture and shape the shell; (5) High-temperature sintering: The shaped shell is sintered at high temperature. In this process, the short fibers are burned into gas and evaporated, thereby forming microporous channels that penetrate the inner and outer surfaces of the shell. These microporous channels are crucial to the performance of the sensor, as they facilitate gas exchange and humidity measurement. (6) Deposition of hydrophobic layer: Finally, the hydrophobic layer material is deposited on the inner surface, outer surface and microporous channel of the outer shell by atomic layer deposition (ALD); the hydrophobic layer is to further enhance the hydrophobic properties of the outer shell, prevent water from accumulating on the surface of the outer shell, and improve the humidity sensor's ability to resist liquid water interference, which is beneficial to the accuracy and reliability of the humidity sensor; Preferably, the length of the short fiber material is selected to be 2 to 5 times the thickness of the shell, in order to ensure that sufficient microporous channels that meet the requirements can be formed during the sintering process; The above steps are used to manufacture a humidity sensor housing with good hydrophobicity and microporous structure to improve the performance of the sensor. The gas passing efficiency of the manufacturing method of the present invention is significantly higher than that of other known porous materials.

[0012] The present invention innovatively proposes to use a closed shell with a hydrophobic property and micron-sized microporous channels to resist the harmful effects of liquid water droplets on the humidity sensor. The use of the hydrophobic layer resists the intrusion of water droplets, and the micron-sized micropores ensure that water molecules in the ambient air can freely penetrate into the humidity sensor. The closed shell reduces the heat dissipation rate of the heating element to the external environment, thereby reducing the overall power consumption of the sensor.

[0013] (1) Protective cover and closed housing: The protective cover is designed to provide additional physical protection without affecting the normal operation of the sensor. Its size is larger than the housing to ensure that it can fully cover and protect the closed housing. This design helps prevent external mechanical shock or damage.

[0014] (2) Microporous channels: The microporous channels on the shell allow gaseous water molecules to pass through while blocking liquid water droplets. This design is based on the size and structure of the micropores, which makes it difficult for water droplets to pass through due to surface tension, while water vapor molecules can pass through freely.

[0015] (3) Hydrophobic layer material: The inner surface, outer surface and wall surface of the microporous channel of the housing are covered with a hydrophobic layer material, which further enhances the sensor's resistance to liquid water. This hydrophobic layer is usually deposited by atomic layer deposition (ALD) technology, which can produce a very uniform and dense film, thereby providing efficient waterproof performance.

[0016] (4) Motor and fan: The built-in motor and fan combination is used to accelerate air flow, ensuring that ambient air can effectively penetrate the housing and contact the humidity sensitive unit. This active air circulation system helps to improve the response speed of the sensor.

[0017] (5) Position of the humidity sensitive unit: The humidity sensitive unit is enclosed inside the housing and located above the fan. This layout allows the airflow generated by the fan to directly act on the humidity sensitive unit, thereby quickly transmitting information about changes in ambient humidity.

[0018] (6) Installed on the base plate: The entire sensor unit is installed on the base plate, leaving a gap between the base plate and the sensor, which helps air circulation and enter the sensor housing.

[0019] (7) Improved measurement accuracy: Through the above design, the sensor can not only respond quickly to changes in ambient humidity, but also avoid interference from liquid water, thereby improving the accuracy of humidity measurement.

[0020] Overall design: The design of the entire sensor forms a whole. This integrated design helps to reduce the impact of the external environment on the sensor performance and is easy to install and maintain.

[0021] In summary, the design of this humidity sensor achieves fast, accurate, and liquid-phase water-resistant humidity measurement by combining a protective cover, a hydrophobic layer material, a microporous channel, a motor and a fan, as well as a reasonable layout. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 : Housing for threaded interface, removable closure not shown.

[0023] Figure 2 : The motor, fan, humidity sensitive unit and casing are all enclosed in the protective cover to form a whole; here, the motor, fan, humidity sensitive unit and casing are not visible because they are enclosed in the protective cover.

[0024] Figure 3 : The motor, fan, humidity sensitive unit and casing are all enclosed in the protective cover to form a whole, and the whole is installed on the base plate, with a gap between the whole and the base plate; here, the motor, fan, humidity sensitive unit and casing are not visible because they are enclosed in the protective cover.

[0025] Figure 4 : A top view of a motor coil winding in the present invention.

[0026] Figure 5 : Another motor coil winding in the present invention is provided with a motor cover, and magnets and fans are not shown in the figure.

[0027] Figure 6 : Another motor coil winding in the present invention is provided with a motor cover, and magnets and fans are not shown in the figure.

[0028] Figure 7 : A fan blade in the present invention. DETAILED DESCRIPTION

[0029] To facilitate understanding of the present invention, the technical solution of the present invention is specifically described below in conjunction with the accompanying drawings and examples.

[0030] A humidity sensor based on atomic layer deposition technology and resistant to liquid phase water interference, including a humidity sensitive unit, characterized in that it also includes a protective cover, a closed shell, a motor, a fan, and a bottom plate. The protective cover has the same shape as the shell, and the size of the protective cover is larger than the shell, so that the protective cover can cover the shell. Figure 2 As shown; The shell has an inner surface and an outer surface, and the shell has densely distributed microporous channels, the microporous channels penetrate the inner surface and the outer surface of the shell, and the inner surface, the outer surface, and the wall of the microporous channels of the shell are all covered with a hydrophobic layer material, so that gaseous water can penetrate inside and outside the shell, but can prevent liquid water droplets in the air from penetrating through the inner and outer surfaces; The motor, fan, humidity sensing unit and housing are all covered and arranged in a protective cover to form a whole, which is mounted on the bottom plate with a gap between the bottom plate so that ambient air can enter the interior of the housing of the humidity sensor; The fan is mounted on the motor, and the humidity sensitive unit is enclosed in the housing and above the fan. The above arrangement enables the fan to accelerate the penetration of ambient air into the housing of the humidity sensor. The flow of gas shortens the response time of the humidity sensor (i.e., the response speed is accelerated), and can quickly respond to changes in ambient air humidity, and avoids interference of liquid water on the humidity sensor, thereby improving measurement accuracy. Preferably, the hydrophobic layer material is any one of polyethylene, polytetrafluoroethylene, polypropylene, fluorocarbon compounds, and silicone.

[0031] Preferably, the hydrophobic layer material covering the inner surface, the outer surface of the shell and the wall surface of the microporous channel is obtained by atomic layer deposition technology.

[0032] The shell is also provided with a wire connection hole for leading the wire connected to the humidity sensitive unit to the external measurement and control circuit, and the wire passes through the connection hole and is sealed.

[0033] As a specific embodiment, in the present invention, the diameter of the microporous channel is between 1 and 20 microns; preferably, the diameter of the microporous channel is between 1 and 10 microns; preferably, the diameter of the microporous channel is between 1 and 4 microns.

[0034] There is no shielding plate or sealing plate on the side of the motor relative to the base plate, and there are gaps between the motor coil windings, so that ambient air can pass through the motor from bottom to top, such as Figure 4 shown.

[0035] Preferably, the fan is mounted on the motor shaft, and a motor cover with holes is provided above the motor coil winding, such as Figure 5 , Figure 6 As shown; The hood covers the motor windings and the fan, and a matching magnet is fixed on the inner circumferential wall to drive the motor coil windings and drive the fan to rotate; The housing is also provided with a wire connection hole for leading the wire connected to the humidity sensitive unit to the external measurement and control circuit, and the wire is sealed through the connection hole; Preferably, the housing is provided with a detachable sealing member for installing the humidity sensitive unit into the housing during manufacturing, and then sealing and installing the housing to form a closed housing; Preferably, the detachable installation between the detachable closure and the housing is a snap-on or threaded installation, such as Figure 1 As shown in the figure, the removable closure is not shown. Since the diameter of the microporous channels on the housing is in the micrometer range, the microporous channels cannot be seen in the figure, which does not mean that there are no microporous channels.

[0036] Preferably, the fan has a plurality of blades, and the projections of the blades on the projection plane of the rotating shaft overlap each other, such as Figure 7 As shown, liquid water droplets in the passing air are thrown onto the inner wall of the motor cover by the blades and finally flow downward to avoid entering the humidity sensor unit enclosed by the housing.

[0037] The design of fan blades is critical to the performance of fans, especially when they are used in humidity sensors. Their design not only affects the efficiency of air flow, but also affects the speed of the sensor's response to humidity changes. In humidity sensors, the purpose and advantages of fan blade design are as follows: (1) Enhanced air flow: The rotation of the fan blades can generate airflow, which helps accelerate the exchange of gas inside and outside the humidity sensor housing, thereby improving the response speed of the sensor.

[0038] (2) Throwing off liquid water: By designing the blades to overlap each other on the projection surface of the rotating shaft, liquid water droplets in the passing air can be thrown onto the inner wall of the motor cover and eventually flow downward, preventing liquid water droplets from entering the humidity sensor unit and ensuring the accuracy of the sensor.

[0039] (3) Reduced interference: The blade design helps reduce the interference of liquid water on the sensor, which is critical to improving measurement accuracy. Liquid droplets may accumulate on the sensor surface, resulting in inaccurate readings, and this design can minimize this risk.

[0040] (4) Improved reliability: The fan blade design helps improve the reliability and durability of the sensor by preventing liquid water from entering the sensor unit. This ensures that the sensor can operate stably under various environmental conditions.

[0041] (5) Optimizing the airflow path: The blade design can optimize the airflow path, allowing air to flow through the sensor more efficiently, improving the uniformity and efficiency of air flow.

[0042] This special design of the fan blades not only helps improve the performance of the humidity sensor, but also helps protect the sensor from potential damage from liquid phase water.

[0043] Preferably, the motor is a flat motor or a sheet motor, such as Figure 4 , 5 , as shown in 6; Preferably, the diameter:thickness ratio of the motor is greater than 5; Preferably, the rotation speed of the motor is between 50 and 1000 RPM (revolutions per minute).

[0044] The regulation of the motor speed is crucial to the performance of the humidity sensor because it directly affects the response speed and accuracy of the sensor. In an embodiment of the present invention, the motor speed is set between 50 and 1000 RPM. This design has the following purposes and advantages: (1) Avoid too low a rotation speed: Too low a rotation speed will result in too low a wind speed, which will make it difficult to effectively improve the response speed of the humidity sensor. The humidity sensor requires sufficient air flow to detect changes in ambient humidity in a timely manner. If the wind speed is too low, the speed at which humidity change information is transmitted to the sensor will be slow, thus affecting the overall response time.

[0045] (2) Preventing excessive rotation speed: Excessive rotation speed may cause the wind speed to be too high, which may cause the liquid water droplets to partially penetrate the shell and enter the humidity sensitive unit under the action of wind pressure. This may not only damage the sensor, but also cause inaccurate measurement data. Therefore, by limiting the maximum rotation speed, this potential interference can be prevented.

[0046] (3) Optimize response speed: Within the speed range of 50~1000RPM, the motor speed can be adjusted according to the actual environmental conditions and measurement requirements to achieve the best response speed. This can ensure that the sensor responds to rapid humidity changes while avoiding the adverse effects caused by excessive wind speed.

[0047] (4) Protecting the sensor: By controlling the speed of the fan, the potential damage to the sensor by liquid water droplets can be reduced. The fan blade design allows the liquid water droplets in the passing air to be thrown onto the inner wall of the motor cover and eventually flow downward, avoiding entering the humidity sensitive unit enclosed by the outer shell, thereby protecting the sensor from damage.

[0048] (5) Improve measurement accuracy: Appropriate wind speed helps improve the measurement accuracy of the humidity sensor. Adjusting the fan speed can ensure that the sensor responds quickly to changes in ambient air humidity while avoiding interference from liquid water.

[0049] In short, the regulation of motor speed is critical to the performance of the humidity sensor. It needs to ensure the response speed and accuracy while avoiding possible physical damage and measurement errors. Through carefully designed fan blades and precisely controlled motor speed, it can ensure that the humidity sensor can provide reliable measurement results under various environmental conditions.

[0050] Preferably, the optimal rotation speed of the motor is determined according to the pore size of the microporous channel of the housing, the surface tension between the hydrophobic layer material and water, and the macroscopic size of the housing.

[0051] The fan is driven by a motor, and the fan speed is set as follows: after the outer surface of the shell with dense microporous channels is fully wetted by fog water, due to the surface tension of the liquid and the capillary phenomenon, the fan blows air and forms an air pressure difference between the outer surface and the inner surface of the shell. The air pressure difference must exceed a certain critical value to drive the liquid water droplets on the outer surface of the shell to penetrate from the microporous channels to the inner surface. This pressure difference is defined as the critical pressure difference, and the corresponding fan speed is defined as the critical speed. The critical speed is obtained by testing the humidity sensor before it is put into use; the actual working speed of the fan is set to be 90% lower than the critical speed.

[0052] In this humidity sensor design, the fan speed is carefully set to ensure efficient operation of the sensor and maintain its accuracy. The following is a detailed analysis of the reasons and advantages of this design: (A) Preventing liquid water penetration: By controlling the fan speed to be lower than 90% of the critical speed, liquid water droplets can be prevented from penetrating from the outer surface of the housing to the inner surface through the microporous channels under high humidity conditions. This is because the microporous channels will not be wetted by liquid water before the critical pressure difference is reached.

[0053] (B) Utilizing surface tension and capillary phenomena: Liquid water tends to remain on the outer surface of the housing in microporous channels due to surface tension and capillary phenomena. These natural phenomena can be used to prevent the penetration of liquid water by keeping the fan speed below the critical speed.

[0054] (C) Determine the critical speed: Before the humidity sensor is put into use, the critical speed at which the critical pressure difference is formed after the outer surface of the shell is fully wetted by the mist is determined through experiments. This provides a scientific basis for setting the fan speed.

[0055] (D) Maintaining air pressure difference: When the fan blows, the air pressure difference between the inner and outer surfaces of the housing is kept below the critical value, which can effectively prevent the penetration of liquid water droplets while allowing gaseous water molecules to pass freely to ensure the normal operation of the humidity sensor.

[0056] (E) Improved measurement accuracy: By controlling the fan speed, it can be ensured that the humidity sensor can provide accurate measurement results under various humidity conditions without being interfered by liquid water.

[0057] (F) Sensor protection: Avoid splashing or atomizing of liquid water caused by high-speed rotating fans. Such splashing or atomizing of liquid water may damage the sensor or cause inaccurate readings.

[0058] (G) Optimize fan life and energy consumption: Setting the fan speed to less than 90% of the critical speed can reduce energy consumption and extend the fan life while ensuring sensor performance.

[0059] (H) Flexibility and adaptability: This design allows the humidity sensor to maintain optimal performance in different environmental conditions, whether it is a foggy day with high humidity or a relatively dry environment.

[0060] In summary, by precisely controlling the fan speed and utilizing the microporous channel structure of the housing, this humidity sensor design is able to maintain a fast response and high-accuracy measurement of ambient humidity changes while preventing interference from liquid phase water.

[0061] In the present invention, the diameter of the microporous channels depends on the diameter of the selected fibers.

[0062] As a specific implementation, in the present invention, the humidity sensitive unit includes a humidity sensitive material, a humidity sensitive material physical property measuring device, a temperature sensor, and a heating element. The temperature sensor is used to measure the temperature of the humidity sensitive material and transmit the measured temperature value to the measurement and control circuit. The measurement and control circuit controls the heating element, and the heating element is used to heat the humidity sensitive material to a constant temperature. The measurement and control circuit has a built-in memory, and the memory stores a three-dimensional mapping table of the humidity sensitive material physical property parameter-temperature-humidity. Preferably, the heating element is a resistive heating element.

[0063] As a specific implementation method, the measurement and control circuit includes an MCU (microcontroller), the MCU has a built-in memory ROM, and the ROM stores a three-dimensional mapping table of physical property parameters of humidity-sensitive materials - temperature - humidity; the MCU calculates all humidity-sensitive resistors R corresponding to the temperature T in the three-dimensional mapping table of physical property parameters of humidity-sensitive materials - temperature - humidity based on the temperature T measured by the temperature sensor element, obtains a sequence of humidity-sensitive resistors R corresponding to the temperature T, and then obtains the humidity H corresponding to the temperature T and the humidity-sensitive resistor R in the sequence based on the humidity-sensitive resistor R measured this time.

[0064] The humidity sensitive material physical property parameter-temperature-humidity three-dimensional mapping table includes a plurality of humidity sensitive resistance R-humidity H curves of the humidity sensor at different temperatures T, that is, R(H) T Curve, each R(H) T The curve records the humidity sensitive resistance R corresponding to different humidity values ​​H.

[0065] The MCU searches the three-dimensional mapping table for the corresponding temperature T according to the temperature T measured by the temperature sensor element; if so, it obtains the humidity sensitive resistor R sequence corresponding to the temperature T in the three-dimensional mapping table, and fits the humidity sensitive resistor R-humidity H function curve R(H) corresponding to the temperature T. T ; Substitute the measured humidity sensitive resistance R into the above function curve R(H) T ; Get the current humidity H value; If it does not exist, obtain the temperature value closest to the temperature T and the second-nearest temperature value in the three-dimensional mapping table, and then obtain two humidity-sensitive resistor R sequences corresponding to the closest temperature value and the second-nearest temperature value, and fit to obtain two humidity-sensitive resistor R-humidity H function curves R(H) corresponding to the closest temperature value and the second-nearest temperature value. T ; Substitute the measured humidity sensitive resistance R into the above function curve R(H) T , and obtain the humidity H corresponding to the nearest temperature value and the second nearest temperature value respectively. 1 , H 2 Value, according to the humidity H 1 , H 2 The interpolation method is used to obtain the humidity H value corresponding to the temperature T measured by the temperature sensor element.

[0066] The fitting formula is as follows: R = R 0 ·exp (A·H+B·H 2 ).

[0067] Where R is the resistance value at temperature T measured by the temperature sensor element, R 0 is the resistance value of the humidity sensor at the temperature T and the relative humidity R is 0, A and B are fitting parameters related to the distribution law and chemical composition of the humidity sensitive material, and H is the relative humidity of the environment.

[0068] As a specific implementation, in the present invention, the housing is provided with a detachable sealing member, which is used to install the humidity sensitive unit into the housing during manufacturing, and then seal and install it into a closed housing.

[0069] As a specific implementation, in the present invention, the physical property parameter of the humidity sensitive material is any one of the dielectric constant, resistivity, and mechanical resonance frequency of the humidity sensitive material; Optionally, when the physical property parameter of the humidity sensitive material is the dielectric constant of the humidity sensitive material, the measurement and control circuit measures the capacitance value of the humidity sensitive material; Optionally, when the physical property parameter of the humidity sensitive material is the resistivity of the humidity sensitive material, the measurement and control circuit measures the resistance value of the humidity sensitive material; Optionally, when the physical property parameter of the humidity sensitive material is the mechanical resonance frequency of the humidity sensitive material, the measurement and control circuit measures the mechanical resonance frequency of the humidity sensitive material.

[0070] Preferably, the detachable installation between the detachable closure and the housing is in a snap-fit ​​or threaded manner.

[0071] As a specific implementation manner, the shell is formed by using a porous material through a mold, and then a hydrophobic film is deposited on the surface thereof by atomic layer deposition technology.

[0072] As a specific implementation, in the present invention, the measurement and control circuit obtains all humidity sensitive resistors corresponding to the temperature according to the three-dimensional mapping table based on the temperature value of the humidity sensitive material measured by the temperature sensor, obtains a humidity sensitive resistor sequence corresponding to the temperature, and then obtains the humidity value of the corresponding temperature and the corresponding humidity sensitive resistor in the sequence based on the humidity sensitive resistor measured at the time; Preferably, the three-dimensional mapping table includes a plurality of humidity sensitive resistor-humidity curves of the humidity sensor at different temperatures, and each curve records humidity sensitive resistor values ​​corresponding to different humidity values.

[0073] Preferably, the hydrophobic layer is any one of polyethylene, polytetrafluoroethylene, polypropylene, fluorocarbon compounds, and silicone.

[0074] The manufacturing method of the housing comprises the following steps: (1) Material selection: Select a certain proportion of powder materials of inorganic minerals or metal oxides and short fiber materials; these materials will be mixed evenly; (2) Making blanks: Add the mixed powder and fiber materials into a fluid binder to make blanks; the binder helps the materials maintain their shape until they are solidified; (3) Mold forming: Use a mold to make the blank into a shell of a preset shape; this step is to ensure that the shape of the shell meets the design requirements; (4) Drying and shaping: Dry the blank in the mold to remove excess moisture and shape the shell; (5) High-temperature sintering: The shaped shell is sintered at high temperature. In this process, the short fibers are burned into gas and evaporated, thereby forming microporous channels that penetrate the inner and outer surfaces of the shell. These microporous channels are crucial to the performance of the sensor, as they facilitate gas exchange and humidity measurement. (6) Deposition of hydrophobic layer: Finally, the hydrophobic layer material is deposited on the inner surface, outer surface and microporous channel of the outer shell by atomic layer deposition (ALD); the hydrophobic layer is to further enhance the hydrophobic properties of the outer shell, prevent water from accumulating on the surface of the outer shell, and improve the humidity sensor's ability to resist liquid water interference, which is beneficial to the accuracy and reliability of the humidity sensor; Preferably, the length of the short fiber material is selected to be 2 to 5 times the thickness of the shell, in order to ensure that sufficient microporous channels that meet the requirements can be formed during the sintering process; Through the above steps, a humidity sensor housing with good hydrophobicity and microporous structure is manufactured to improve the performance of the sensor.

[0075] The housing is also provided with a wire connection hole, which is used to lead the wire connected to the humidity sensitive unit to the external measurement and control circuit, and the wire passes through the connection hole and is sealed; Preferably, the housing is provided with a detachable sealing member for installing the humidity sensitive unit into the housing during manufacturing, and then sealing and installing the housing into a closed housing; Figure 2 As shown in the figure, the four metal pillars shown at the bottom serve as the extraction sensing electrodes of the humidity sensitive unit and the extraction electrodes of the heating element, and also serve as the pillars of the motor, fan, humidity sensitive unit, and the shell are all covered and arranged in the protective cover to form a whole, and the whole is installed on the bottom plate. There is a gap between the whole and the bottom plate for ambient air to enter the inside of the shell of the humidity sensor, such as Figure 3 shown.

[0076] Preferably, the detachable installation between the detachable closure and the housing is in a snap-fit ​​or threaded manner.

[0077] Preferably, the inorganic mineral powder can be selected from any one or more of calcium carbonate, mica powder, talc powder, wollastonite powder, and kaolin; Preferably, the metal oxide powder can be selected from any one or more of aluminum oxide, iron oxide, ferric oxide, zinc oxide, and titanium dioxide.

[0078] Preferably, the hydrophobic layer material obtained by atomic layer deposition (ALD) is any one of the following materials: metal fluoride, alkyl silicone, fluorine-containing polymer, silicone, and long-chain alkane.

[0079] In the present invention, the length of the short fiber material may be selected to be several times the thickness of the shell.

[0080] Preferably, the length of the short fiber material is 2 to 5 times the thickness of the shell.

[0081] For example, if the shell thickness is 1 mm, a fiber material with a length of 2 to 5 mm is selected. Based on such a length ratio selection, according to statistical methods, during the mixing process of the fiber material, most of the fibers will penetrate the shell body, thereby forming a microporous channel that penetrates the inner and outer surfaces of the shell after sintering. In the present invention, the manufacturing process of the detachable closure is the same as the manufacturing process of the shell.

[0082] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention. The contents not described in detail in this specification belong to the prior art known to professional and technical personnel in the field.

Claims

1. A humidity sensor based on atomic layer deposition technology and resistant to liquid phase water interference, comprising a humidity sensitive unit, characterized in that: It also includes a protective cover, a closed housing, a motor, a fan, and a bottom plate. The protective cover has the same shape as the housing, and the size of the protective cover is larger than the housing, so that the protective cover can cover the housing. The shell has an inner surface and an outer surface, and the shell has densely distributed microporous channels, the microporous channels penetrate the inner surface and the outer surface of the shell, and the inner surface, the outer surface, and the wall of the microporous channels of the shell are all covered with a hydrophobic layer material, so that gaseous water can penetrate inside and outside the shell, but can prevent liquid water droplets in the air from penetrating through the inner and outer surfaces; The motor, fan, humidity sensing unit and housing are all covered and arranged in a protective cover to form a whole, which is mounted on the bottom plate with a gap between the bottom plate so that ambient air can enter the interior of the housing of the humidity sensor; The fan is mounted on the motor, and the humidity sensitive unit is enclosed in the housing and above the fan. The above arrangement enables the fan to accelerate the penetration of ambient air into the housing of the humidity sensor. The flow of gas shortens the response time of the humidity sensor (i.e., the response speed is accelerated), and can quickly respond to changes in ambient air humidity, and avoids interference of liquid water on the humidity sensor, thereby improving measurement accuracy. Preferably, the hydrophobic layer material is any one of polyethylene, polytetrafluoroethylene, polypropylene, fluorocarbon, and siloxane; Preferably, the hydrophobic layer material covering the inner surface, the outer surface of the shell and the wall surface of the microporous channel is obtained by atomic layer deposition technology.

2. The humidity sensor according to claim 1, characterized in that: The diameter of the microporous channel is between 1 and 20 microns; preferably, the diameter of the microporous channel is between 1 and 10 microns; preferably, the diameter of the microporous channel is between 1 and 4 microns.

3. The humidity sensor according to claim 1, characterized in that: There is no shielding plate or sealing plate on one side of the motor relative to the base plate, and there are gaps between the motor coil windings, so that ambient air can pass through the motor from bottom to top; Preferably, the fan is mounted on the motor shaft, and a motor cover with holes is provided above the motor coil winding; The hood covers the motor windings and the fan, and a matching magnet is fixed on the inner circumferential wall to drive the motor coil windings and drive the fan to rotate; Preferably, the fan has multiple blades, and the projections of the blades on the projection surface of the rotating shaft overlap each other, so that liquid water droplets in the flowing air are thrown by the blades onto the inner wall of the motor cover and finally flow downward to avoid entering the humidity sensor unit enclosed by the outer shell.

4. The humidity sensor according to any one of claims 1 to 3, characterized in that: The motor is a flat motor or a sheet motor; Preferably, the diameter:thickness ratio of the motor is greater than 5; Preferably, the speed of the motor is between 50 and 1000 RPM (revolutions / minute). A too low speed will result in too low wind speed, making it difficult to effectively improve the response speed of the humidity sensor. A too high speed will result in too high wind speed, causing the liquid water droplets to partially penetrate the housing and enter the humidity sensitive unit under wind pressure. Preferably, the optimal rotation speed of the motor is determined according to the pore size of the microporous channel of the housing, the surface tension between the hydrophobic layer material and water, and the macroscopic size of the housing.

5. The humidity sensor according to claim 1, wherein: The manufacturing method of the housing comprises the following steps: (1) Material selection: Select a certain proportion of powder materials of inorganic minerals or metal oxides and short fiber materials; these materials will be mixed evenly; (2) Making blanks: Add the mixed powder and fiber materials into a fluid binder to make blanks; the binder helps the materials maintain their shape until they are solidified; (3) Mold forming: Use a mold to make the blank into a shell of a preset shape; This step is to ensure that the shape of the shell meets the design requirements; (4) Drying and shaping: Dry the blank in the mold to remove excess moisture and shape the shell; (5) High-temperature sintering: The shaped shell is sintered at high temperature. During this process, the short fibers are burned into gas and evaporated, thereby forming microporous channels in the shell that penetrate the inner and outer surfaces. These microporous channels are crucial to the performance of the sensor, as they facilitate gas exchange and humidity measurement; (6) Deposition of hydrophobic layer: Finally, the hydrophobic layer material is deposited on the inner surface, outer surface and microporous channel of the outer shell by atomic layer deposition (ALD); the hydrophobic layer is to further enhance the hydrophobic properties of the outer shell, prevent water from accumulating on the surface of the outer shell, and improve the humidity sensor's ability to resist liquid water interference, which is beneficial to the accuracy and reliability of the humidity sensor; Preferably, the length of the short fiber material is selected to be 2 to 5 times the thickness of the shell, in order to ensure that sufficient microporous channels that meet the requirements can be formed during the sintering process; Through the above steps, a humidity sensor housing with good hydrophobicity and microporous structure is manufactured to improve the performance of the sensor.

6. The humidity sensor according to any one of claims 1 to 5, characterized in that: The housing is also provided with a wire connection hole for leading the wire connected to the humidity sensitive unit to the external measurement and control circuit, and the wire is sealed through the connection hole; Preferably, the housing is provided with a detachable sealing member for installing the humidity sensitive unit into the housing during manufacturing, and then sealing and installing the housing to form a closed housing; Preferably, the detachable installation between the detachable closure and the housing is in a snap-fit ​​or threaded manner.

7. The humidity sensor according to any one of claims 1 to 6, characterized in that: The humidity sensitive unit includes a humidity sensitive material, a humidity sensitive material physical property measuring device, a temperature sensor, and a heating element. The temperature sensor is used to measure the temperature of the humidity sensitive material and transmit the measured temperature value to the measurement and control circuit. The measurement and control circuit controls the heating element. The heating element is used to heat the humidity sensitive material to a constant temperature. The measurement and control circuit has a built-in memory. The memory stores a three-dimensional mapping table of the humidity sensitive material physical property parameter, temperature, and humidity. Optionally, the physical property parameter of the humidity sensitive material is any one of a dielectric constant, a resistivity, and a mechanical resonance frequency of the humidity sensitive material; Optionally, when the physical property parameter of the humidity sensitive material is the dielectric constant of the humidity sensitive material, the measurement and control circuit measures the capacitance value of the humidity sensitive material; Optionally, when the physical property parameter of the humidity sensitive material is the resistivity of the humidity sensitive material, the measurement and control circuit measures the resistance value of the humidity sensitive material; Optionally, when the physical property parameter of the humidity sensitive material is the mechanical resonance frequency of the humidity sensitive material, the measurement and control circuit measures the mechanical resonance frequency of the humidity sensitive material; Preferably, the measurement and control circuit obtains all humidity sensitive resistors corresponding to the temperature according to the three-dimensional mapping table based on the temperature value of the humidity sensitive material measured by the temperature sensor, obtains a humidity sensitive resistor sequence corresponding to the temperature, and then obtains the humidity value of the corresponding temperature and the corresponding humidity sensitive resistor in the sequence based on the humidity sensitive resistor measured at the time; Preferably, the three-dimensional mapping table includes a plurality of humidity sensitive resistor-humidity curves of the humidity sensor at different temperatures, and each curve records the humidity sensitive resistor values ​​corresponding to different humidity values. Preferably, the heating element is a resistive heating element.

8. The humidity sensor according to claim 1, characterized in that: The fan is driven by a motor, and the fan speed is set as follows: after the outer surface of the shell with dense microporous channels is fully wetted by fog water, due to the surface tension of the liquid and the capillary phenomenon, the fan blows air and forms an air pressure difference between the outer surface and the inner surface of the shell. The air pressure difference must exceed a certain critical value to drive the liquid water droplets on the outer surface of the shell to penetrate from the microporous channels to the inner surface. This pressure difference is defined as the critical pressure difference, and the corresponding fan speed is defined as the critical speed. The critical speed is obtained by testing the humidity sensor before it is put into use; the actual working speed of the fan is set to be 90% lower than the critical speed.

9. The humidity sensor according to claim 5, characterized in that: The inorganic mineral powder may be selected from any one or more of calcium carbonate, mica powder, talcum powder, wollastonite powder and kaolin; The metal oxide powder can be selected from any one or more of aluminum oxide, iron oxide, ferric oxide, zinc oxide, and titanium dioxide.

10. The humidity sensor according to claim 5, characterized in that: The hydrophobic layer material obtained by the atomic layer deposition (ALD) method is any one of the following materials: metal fluoride, alkyl silicone, fluorine-containing polymer, silicone, and long-chain alkane.

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