Humidity sensor suitable for outdoor environment

Abstract

The invention provides a humidity sensor suitable for being used in an outdoor environment so as to cope with the outdoor severe environment and reduce power consumption. The shell is provided with the micropore channel which penetrates through the inner surface and the outer surface of the shell, so that gas can penetrate through the inside and the outside of the shell, and the sensitivity and the response speed of the humidity sensor are improved. The closed shell is favorable for maintaining the stability of temperature and humidity in the sensor, reducing the influence of external environment change on the internal conditions of the sensor, reducing the influence of external air flow on the internal environment of the sensor, and reducing heat exchange caused by convection or radiation, thereby reducing the fluctuation of internal temperature and humidity. The vent hole allows the ambient air to directly contact with the sensor, so that the humidity reading of the sensor can be quickly matched with the ambient humidity, thereby reducing the response time.

Description

Technical Field

[0001] The invention relates to a humidity sensor suitable for outdoor environment, and the IPC classification number is G01N27 / 00. Background Art

[0002] The working principle of humidity sensors is mainly based on the hygroscopic properties of materials, such as hygroresistors and humidity-sensitive capacitors. Capacitive humidity sensors use the relationship between dielectric constant and humidity. When humidity increases, the dielectric constant of hygroscopic materials changes, causing the capacitance value of capacitors to change. Resistive humidity sensors are based on the sensitivity of conductive materials to humidity. When humidity increases, conductive materials absorb moisture, causing resistance values ​​to change. In addition, there are also ways to measure humidity by using the difference in thermal conductivity between humid air and dry air, the energy loss of microwaves or ultrasonic waves when propagating in air containing water vapor, and water vapor absorbing infrared rays of specific wavelengths.

[0003] Humidity sensors have a wide range of application scenarios, including but not limited to the following aspects: Meteorological observations: used for weather forecasting, climate research and natural disaster monitoring.

[0004] Agriculture: Monitor soil moisture to ensure crops are properly irrigated.

[0005] Manufacturing: Monitor humidity in the production environment to prevent components from getting wet and affecting product performance.

[0006] Healthcare: Monitor humidity in wards to ensure patient comfort and the normal operation of medical equipment.

[0007] Indoor environmental control: Used in smart home devices such as smart thermostats and air conditioning systems to ensure indoor humidity is within a comfortable range.

[0008] Industrial production: Monitor and control humidity in industries such as textiles, electronics, precision machinery, and ceramics to ensure product quality.

[0009] Item storage: Monitor and control humidity in the warehouse to prevent items from being damaged by moisture or dryness.

[0010] Protection of precision instruments: Maintain appropriate humidity conditions in the laboratory and equipment operating environment.

[0011] With the development of technology, the application areas of humidity sensors will be further expanded, especially in smart home, environmental protection and agricultural technology. In the future, humidity sensors will develop in a more intelligent, precise and networked direction.

[0012] However, when humidity sensors are used outdoors, they will inevitably encounter liquid water such as rain and fog droplets, which will have many adverse effects. Liquid water droplets may have the following adverse effects on humidity sensors: (1) Reduced sensor accuracy: Humidity sensors are usually designed to measure water vapor content in the air, not liquid water. Water droplets may interfere with the normal operation of the sensor, resulting in inaccurate measurement results. For example, capacitive or resistive humidity sensors may change their electrical properties due to direct contact with water droplets, thereby affecting measurement accuracy.

[0013] (2) Mechanical damage: Liquid water droplets may enter the internal structure of the sensor, causing damage or corrosion to the mechanical parts, especially for those sensors that are not waterproof.

[0014] (3) Damage to electronic components: Water droplets may cause short circuits in electronic components, especially if the water droplets contain impurities, which may increase conductivity and cause permanent damage to the sensor.

[0015] (4) Longer response time: Under low temperature conditions, the response time of the humidity sensor may be longer and the sensitivity may decrease. This is because the presence of liquid water droplets may affect the sensor's response speed to water vapor.

[0016] (5) Shortened sensor life: Long-term exposure to liquid water droplets may shorten the service life of the sensor because the water droplets may gradually erode the material and structure of the sensor.

[0017] (6) Calibration difficulties: Due to the influence of water droplets, the sensor may need to be calibrated more frequently to ensure the accuracy of the measurement results.

[0018] (7) Data drift: When the humidity sensor is in high humidity conditions, the humidity measuring element is easily wetted, resulting in abnormally high humidity, which makes the identified cloud layer thicker. This may cause data drift, especially in high humidity environments.

[0019] On the other hand, humidity sensors usually need to be equipped with heaters when in use so that they can work in the optimal sensitive temperature area. When humidity sensors are used outdoors, they will face the problem of rapid heat dissipation from the heater into the environment, which will greatly increase their power consumption. Summary of the invention

[0020] The purpose of the present invention is to provide a humidity sensor suitable for outdoor use, so as to cope with the harsh outdoor environment and reduce power consumption. The specific technical solution to achieve the purpose of the present invention is: A humidity sensor suitable for use in an outdoor environment, comprising a humidity sensitive unit, characterized in that: it also comprises a closed housing, the housing having an inner surface and an outer surface, and the housing is made of a microporous channel material, the microporous channel penetrates the inner surface and the outer surface of the housing, so that gas can pass through the inside and outside of the housing; 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.

[0021] 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.

[0022] 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 physical property parameters of the humidity sensitive material - temperature - humidity.

[0023] In the present invention, the measurement and control circuit obtains all humidity sensitive resistors corresponding to the temperature according to the temperature value of the humidity sensitive material measured by the temperature sensor according to the three-dimensional mapping table, 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 according to the humidity sensitive resistor obtained by the current measurement.

[0024] As another implementation method, a humidity sensor suitable for use in outdoor environments includes a humidity sensitive unit and a closed shell, the shell having an inner surface and an outer surface, and the shell is made of a micron-level 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 shell body is made of a hydrophobic material, and the microporous channel on the shell is used to block liquid water droplets in the air; the humidity sensitive unit is sealed in the shell; the shell is also provided with a wire connection hole, which is used to lead the wire connected to the humidity sensitive unit to an external measurement and control circuit, and the wire is sealed through the connection hole.

[0025] Preferably, in the above example, the shell is made of any one of perlite, clamshell, montmorillonite, attapulgite, natural rubber, and natural asphalt. Of course, the hydrophobic material here can also be other types of materials, not limited to the above. In the present invention, as an optional embodiment, the hydrophobic material is mainly selected from two categories: natural hydrophobic materials and artificially synthesized hydrophobic materials.

[0026] However, not all porous materials are suitable for use as the shell material of the present invention. The reason is that although some porous materials have holes with a certain distribution density inside, the holes are not connected or the connectivity is poor. Therefore, such porous materials make it difficult for water molecules in the ambient air to pass through the shell and reach the humidity sensitive unit.

[0027] The present invention innovatively proposes a shell manufacturing method suitable for solving the technical problem proposed by the present invention, so that the microporous channel can penetrate the inner and outer surfaces of the shell, thereby allowing gas to pass through the inside and outside of the shell, thereby improving the sensitivity and response speed of the humidity sensor.

[0028] The shell manufacturing method is as follows: A certain proportion of inorganic mineral or metal oxide powder material and short fiber material are selected, the powder material and the fiber material are evenly mixed, and a fluid binder is added to form a blank; The blank is made into a shell of a preset shape using a mold, which is then dried and shaped before being sintered at high temperature. During the high-temperature sintering process, the short fibers are burned into gases such as carbon dioxide and evaporated, forming microporous channels in the shell.

[0029] In the present invention, the length of the short fiber material may be selected to be several times the thickness of the shell.

[0030] Preferably, the length of the short fiber material is 2 to 5 times the thickness of the shell.

[0031] For example, if the shell thickness is 1mm, then a fiber material with a length of 2-5mm 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 penetrating the inner and outer surfaces of the shell after sintering.

[0032] 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).

[0033] Atomic layer deposition (ALD) technology has the following advantages over other methods when making thin films on the surface and in the pores of porous materials: (1) High-precision thickness control: ALD technology can achieve atomic-level thickness control. By controlling the number of reaction cycles, the thickness of the film can be precisely controlled, which is crucial for applications that require precise control of film properties.

[0034] (2) Excellent three-dimensional conformality: ALD technology can form uniform films on substrates of complex shapes, including the internal surfaces of porous materials. This conformality makes ALD very suitable for porous materials because it can deposit films uniformly inside and outside the holes without forming pinholes or uneven coverage.

[0035] (3) High flatness and pinhole-free properties: The surface of the film deposited by ALD technology is very flat, and due to its self-limiting growth mechanism, the film is pinhole-free, which is very important for applications that require high barrier properties or high coverage.

[0036] (4) Good adhesion: ALD technology forms a thin film on the substrate surface through chemical adsorption, so it has excellent adhesion, which is very important for improving the mechanical stability and durability of the film.

[0037] (5) Low thermal budget and low temperature deposition capability: ALD technology can be performed at lower temperatures, which is very useful for thermally sensitive materials in porous materials or applications that require maintaining specific temperature conditions.

[0038] (6) Wide range of material applicability: ALD technology can deposit a variety of materials, including metals, oxides, nitrides, polymers, etc., which provides a wide range of options for surface modification and functionalization of porous materials.

[0039] ALD technology can achieve ultra-thin large-area preparation of porous material membranes, which is of great significance for industrial-scale applications.

[0040] The gas passing efficiency of the manufacturing method of the present invention is significantly higher than that of other known porous materials.

[0041] Beneficial effects: 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.

[0042] In the present invention, a closed housing is used in the humidity sensor, which has the following benefits: (1) It can effectively isolate the direct contact between the inside of the sensor and the external environment, reduce the heat generated by the internal heating element and dissipate to the outside, thereby improving energy efficiency.

[0043] (2) Stabilizing the internal environment: A closed housing helps maintain the temperature and humidity inside the sensor and reduces the impact of external environmental changes on the internal conditions of the sensor, which is beneficial for accurate measurement.

[0044] (3) Reduce external interference: The closed design can reduce the impact of external air flow on the internal environment of the sensor, reduce heat exchange caused by convection or radiation, and thus reduce fluctuations in internal temperature and humidity.

[0045] (4) Precisely controlled heating: In some humidity sensors, a heating element may be required to regulate the humidity inside the sensor. A closed housing allows for more precise control of the effect of the heating element because the heat is not easily lost to the environment.

[0046] (5) Improved measurement accuracy: By reducing unnecessary heat dissipation, the enclosed housing helps improve the measurement accuracy of the sensor, especially in applications that require precise control and measurement of temperature and humidity.

[0047] In the present invention, a housing design with micron-level air permeability is adopted in the humidity sensor, which has the following advantages: (1) Improved response speed: The vent holes allow ambient air to come into direct contact with the sensor, which can quickly match the sensor's humidity reading to the ambient humidity, thereby reducing the response time. Housing designs with large dead volumes and / or small apertures may separate the sensor from the environment, increasing the response time. Therefore, in order to achieve a fast response time, the present invention considers designing a housing that allows airflow through the sensor.

[0048] (2) Improve measurement accuracy: Ventilation holes help reduce the dead volume inside the housing. The smaller the dead volume, the less air needs to be exchanged, which helps the sensor adapt to environmental changes more quickly and improves measurement accuracy. At the same time, large openings on the housing can improve ventilation and increase contact with the environment, which also helps improve measurement accuracy.

[0049] (3) Adaptability to harsh environments: In some special environments, such as high temperature, high humidity or dusty environments, the air holes combined with appropriate filter materials can prevent water vapor and dust from entering the sensor, thereby protecting the sensor and extending its service life. The waterproof and breathable membrane used in the present invention effectively prevents the sensor opening from contacting water vapor and dust, maintaining the sensitivity and accuracy of the sensor.

[0050] (4) Reduce internal condensation: In an environment with large temperature changes, the air holes on the outer shell can help balance the temperature difference between the inside and outside, reduce the formation of internal condensation, and thus avoid measurement errors caused by condensation.

[0051] (5) Easy maintenance and cleaning: The design of the air vents also facilitates the maintenance and cleaning of the sensor because they allow air circulation and reduce the accumulation of dust and other contaminants inside the sensor.

[0052] In the present invention, the housing design with ventilation holes is crucial to the performance and reliability of the humidity sensor. It can not only improve the response speed and measurement accuracy of the sensor, but also protect the sensor in harsh environments and extend its service life.

[0053] In the present invention, the humidity sensor is provided with a heating element, which has many benefits: (1) Prevent condensation: In low temperature environments, condensation may occur on the surface of the humidity sensor, forming water droplets. Heating can prevent the sensor surface temperature from being too low, thereby avoiding the formation of condensed water and ensuring accurate measurement of the sensor.

[0054] (2) Improving response speed: Some humidity sensors, such as capacitive or resistive, detect humidity by measuring changes in the electrical properties of the material. Heating can speed up the sensor's response to changes in ambient humidity and increase its measurement speed.

[0055] (3) Reduce creep effect: Creep refers to the phenomenon that the performance of the sensor gradually changes after continuous moisture absorption. Heating can reduce the creep effect and maintain the long-term stability of the sensor.

[0056] (4) Anti-pollution: Heating can reduce the accumulation of pollutants on the sensor surface and improve the accuracy and reliability of the sensor.

[0057] (5) Temperature compensation: The measurement results of humidity sensors are often affected by temperature changes. Heating and measuring the temperature can be used to temperature compensate the humidity readings to improve the accuracy of the measurement.

[0058] (6) Improve low temperature performance: In low temperature environments, the humidity sensitivity performance of some humidity sensors may decrease. The heating structure can improve the performance of humidity sensors in low temperature environments, reduce the recovery response time, and improve the nonlinearity and stability of the sensor. DETAILED DESCRIPTION

[0059] To facilitate understanding of the present invention, the technical solution of the present invention is specifically described below in conjunction with examples.

[0060] A humidity sensor suitable for use in an outdoor environment, comprising a humidity sensitive unit and a closed housing, wherein the housing has an inner surface and an outer surface, and the housing is made of a microporous material, wherein the micropores penetrate the inner surface and the outer surface of the housing, so that gas can pass through the inside and outside of the housing; 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 micropores on the shell are 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.

[0061] As a specific embodiment, in the present invention, the diameter of the microporous channel is between 1 and 100 microns; optionally, the diameter of the microporous channel is between 1 and 10 microns; optionally, the diameter of the microporous channel is between 1 and 4 microns.

[0062] Here, the diameter of the microporous channel depends on the diameter of the selected fiber. The thinner the fiber, the smaller the diameter of the microporous channel.

[0063] 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.

[0064] 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.

[0065] 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.

[0066] 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 , two humidity values ​​H1 and H2 corresponding to the nearest temperature value and the second nearest temperature value are obtained respectively. According to the obtained humidity H1 and H2 values, the humidity H value corresponding to the temperature T measured by the temperature sensor element is obtained by interpolation method.

[0067] The fitting formula is as follows: R = R0 exp (A H + B H 2 ).

[0068] Among them, R is the resistance value at temperature T measured by the temperature sensor element, R0 is the resistance value of the humidity sensor at temperature T and relative humidity R is 0, A and B are fitting parameters related to the distribution law and chemical composition of humidity sensitive materials, and H is the relative humidity of the environment.

[0069] 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.

[0070] 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.

[0071] Preferably, the detachable installation between the detachable closure and the housing is in a snap-fit ​​or threaded manner.

[0072] 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.

[0073] 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.

[0074] Preferably, the hydrophobic layer is any one of polyethylene, polytetrafluoroethylene, polypropylene, fluorocarbon compounds, and silicone.

[0075] As a specific example, a humidity sensor suitable for use in outdoor environments includes a humidity sensitive unit and a closed shell, wherein the shell has an inner surface and an outer surface, and the shell is made of a micron-level microporous material, wherein the micropores penetrate the inner surface and the outer surface of the shell, so that gas can pass through the inside and outside of the shell; the shell body is made of a hydrophobic material, and the micropores on the shell are used to block liquid water droplets in the air; the humidity sensitive unit is sealed in the shell; the shell is also provided with a wire connection hole, which is used to lead the wires connected to the humidity sensitive unit to the external measurement and control circuit, and the wires are sealed through the connection hole.

[0076] Preferably, in the above example, the shell is made of any one of perlite, clam shell, montmorillonite, attapulgite, natural rubber, and natural asphalt. Of course, the hydrophobic material here can also be other types of materials, not limited to the above types.

[0077] In the present invention, as an optional embodiment, the hydrophobic material mainly includes two categories: natural hydrophobic materials and artificially synthesized hydrophobic materials.

[0078] Naturally hydrophobic materials include: (1) Porous media materials, such as perlite and clam shells, have a large number of tiny pores and surface protrusions, which can effectively prevent moisture from adhering.

[0079] (2) Silicate materials, such as montmorillonite and attapulgite, have a large amount of negative charge on their surface, which forms an electrostatic adsorption effect, making it difficult for water molecules to adhere to their surface.

[0080] (3) Natural polymer materials, such as natural rubber and natural asphalt, are extremely hydrophobic due to their special molecular structure and chemical properties.

[0081] ‌Artificially synthesized hydrophobic materials‌ include: ‌ (1) Polymer coating‌: The hydrophobic properties of the material are enhanced by coating the polymer coating on the surface of the substrate, such as polyethylene, polytetrafluoroethylene, etc.

[0082] (2) Nanomaterials: Materials prepared using nanotechnology have unique surface structures and physical properties that can effectively inhibit the contact of water molecules.

[0083] In the present invention, a preferred shell manufacturing method can allow micropores to penetrate the inner and outer surfaces of the shell, thereby allowing gas to pass through the inside and outside of the shell, thereby improving the sensitivity and response speed of the humidity sensor.

[0084] The specific steps of the above shell manufacturing method are as follows: A certain proportion of inorganic mineral or metal oxide powder material and short fiber material are selected, the powder material and the fiber material are evenly mixed, and a fluid binder is added to form a blank; The blank is made into a shell of a preset shape using a mold, which is then dried and shaped before being sintered at high temperature. During the high-temperature sintering process, the short fibers are burned into gases such as carbon dioxide and evaporated, forming microporous channels in the shell.

[0085] In the present invention, the length of the short fiber material is selected to be several times the thickness of the shell. Preferably, the length of the short fiber material is 2 to 5 times the thickness of the shell.

[0086] For example, if the shell thickness is 1mm, then a fiber material with a length of 2-5mm 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 penetrating the inner and outer surfaces of the shell after sintering.

[0087] 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).

[0088] As a specific embodiment, a material having hydrophobic properties, such as oxides, fluorides, etc., can be deposited on the shell by ALD technology to form a hydrophobic layer, such as Y2O3, to produce a surface with a water contact angle of about 158°, thereby manufacturing a superhydrophobic surface.

[0089] As a specific implementation, a fluorine-containing material can be used as a precursor: due to its low surface energy characteristics, the fluorine-containing material is often used as a precursor for preparing a hydrophobic layer. The ALD technology can accurately control the deposition of the fluorine-containing material to form a uniform and continuous hydrophobic film.

[0090] As a specific implementation, a micron / nano composite rough structure can be constructed on the substrate surface by ALD technology, which can increase the surface roughness and thus enhance the surface hydrophobicity. For example, a multiphase aluminum oxide micro-nano structure coating is prepared on the surface of an aluminum alloy by ALD technology, and Al2O3 nanophases based on negative surface energy are embedded in the microstructure surface of the low surface energy shell by micro-etching to achieve overall super-hydrophobic performance.

[0091] As a specific embodiment, Er2O3 and Dy2O3 can be deposited by thermal plasma enhanced ALD (PE-ALD) using Er and Dy precursors, and these materials show high hydrophobicity with water contact angles as high as 90°.

[0092] The inorganic minerals and metal oxide powders suitable for making the above-mentioned shell mainly include the following: aluminum oxide, aluminum nitride, beryllium oxide, mullite, magnesium oxide, lanthanum oxide, STO, AZO, B4C, etc.

[0093] 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 suitable for use in an outdoor environment, comprising a humidity sensitive unit, characterized in that: Also included is 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, 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 manufacturing method of the housing is as follows: A certain proportion of inorganic mineral or metal oxide powder material and short fiber material are selected, the powder material and the fiber material are evenly mixed, and a fluid binder is added to form a blank; The blank is made into a shell of a preset shape by using a mold, and then sintered at high temperature after drying and shaping. During the high-temperature sintering process, the short fibers are burned into gas and volatilized, forming microporous channels in the shell body that penetrate the inner and outer surfaces of the shell; Finally, the hydrophobic layer material is deposited on the inner surface, outer surface and microporous channel of the outer shell by atomic layer deposition method; Preferably, the length of the short fiber material is selected to be 2 to 5 times the thickness of the shell; Optionally, a material having hydrophobic properties, such as oxides, fluorides, etc., is deposited on the shell by an atomic layer deposition method to form a hydrophobic layer, such as Y2O3, to produce a surface with a water contact angle of about 158°, thereby manufacturing a superhydrophobic surface; Optionally, a fluorine-containing material is used as a precursor by an atomic layer deposition method: fluorine-containing materials are often used as precursors for preparing hydrophobic layers due to their low surface energy properties; Optionally, a micron / nano composite rough structure is constructed on the shell surface by an atomic layer deposition method, and this structure can increase the roughness of the surface, thereby enhancing the hydrophobicity of the surface; Alternatively, Er2O3 or Dy2O3 were deposited by thermal plasma-enhanced ALD (PE-ALD) using Er and Dy precursors, and these materials showed high hydrophobicity with water contact angles up to 90°.

2. The humidity sensor according to claim 1, characterized in that: The diameter of the microporous channel is between 1 and 100 microns; optionally, the diameter of the microporous channel is between 1 and 10 microns; optionally, the diameter of the microporous channel is between 1 and 4 microns.

3. The humidity sensor according to claim 1, 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. Preferably, the heating element is a resistive heating element.

4. The humidity sensor according to claim 1, characterized in that: The housing is provided with a detachable closing piece, which is used to install the moisture sensitive unit into the housing during manufacturing, and then to seal and install the housing into a closed type.

5. The humidity sensor according to claim 3, characterized in that: 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.

6. The humidity sensor according to claim 4, characterized in that: The detachable installation between the detachable closure and the shell adopts a snap-on type or a threaded type.

7. The humidity sensor according to claim 1, characterized in that: The shell is formed by using a porous material through a mold, and a hydrophobic film is deposited on the surface thereof by using an atomic layer deposition technique.

8. The humidity sensor according to claim 3, characterized in that: 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.

9. The humidity sensor according to claim 1 or 7, characterized in that: The hydrophobic layer is any one of polyethylene, polytetrafluoroethylene, polypropylene, fluorocarbon compounds, and silicone.

10. A humidity sensor suitable for use in an outdoor environment, comprising a humidity sensitive unit, characterized in that: It also includes a closed shell, the shell having an inner surface and an outer surface, and the shell is made of a micron-level microporous material, the micropores penetrate the inner surface and the outer surface of the shell, so that gas can pass through the inside and outside of the shell; the shell body is made of a hydrophobic material, and the micropores on the shell are used to block liquid water droplets in the air; The humidity sensitive unit is sealed in the shell; 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.

11. The humidity sensor according to claim 10, characterized in that: The shell is made of any one of perlite, clam shell, montmorillonite, attapulgite, natural rubber and natural asphalt.