Humidity sensor

Abstract

The present application provides a humidity sensor including a substrate, a single electrode structure, and a sensing layer or a three-dimensional sensing structure. The sensing layer or the three-dimensional sensing structure is disposed on the substrate. The single electrode structure is disposed on a surface of the sensing layer or the three-dimensional sensing structure, and a relative humidity is obtained according to a resistance value of two end points of the single electrode structure.

Description

Technical Field

[0001] The present invention relates to a sensor, and in particular to a humidity sensor. Background Art

[0002] Generally, humidity sensors are divided into resistive and capacitive types. Resistive humidity sensors utilize the property that the sensing layer itself changes in resistance due to humidity. By measuring the resistance of the sensing layer itself, the relative humidity is converted. They have a fast response speed and are less expensive than capacitive humidity sensors. However, the resistance measured by resistive humidity sensors is not linearly related to relative humidity and requires logarithmic processing, resulting in poor interchangeability. Capacitive humidity sensors utilize the property that the dielectric constant of the sensing layer changes due to humidity, causing the capacitance value to change with humidity. Therefore, relative humidity can be obtained by measuring the capacitance of the sensing layer. The capacitance value and relative humidity are linearly related, resulting in good interchangeability. However, capacitive humidity sensors have a slower response speed and are more expensive than resistive humidity sensors. Summary of the Invention

[0003] The present invention is directed to a humidity sensor, which is a resistive humidity sensor in which resistance and relative humidity have a linear relationship.

[0004] According to an embodiment of the present invention, a humidity sensor includes a substrate, a sensing layer, and a single electrode structure. The sensing layer is disposed on the substrate. The single electrode structure is disposed on a surface of the sensing layer and measures relative humidity based on resistance values ​​at two ends of the single electrode structure.

[0005] In the humidity sensor according to the embodiment of the present invention, the single electrode structure is a linear electrode, and the water absorption thickness expansion rate of the sensing layer is less than 10%.

[0006] In the humidity sensor according to the embodiment of the present invention, the single electrode structure is a serpentine electrode or a spiral electrode, and the water absorption thickness expansion rate of the sensing layer is between 0% and 10%.

[0007] In the humidity sensor according to the embodiment of the present invention, the material of the sensing layer includes polyimide, sodium polystyrene sulfonate, polymethyl methacrylate, cellulose acetate butyrate or benzocyclobutene.

[0008] In the humidity sensor according to the embodiment of the present invention, a ratio of the thickness of the single electrode structure to the thickness of the sensing layer is less than 1.

[0009] According to another embodiment of the present invention, a humidity sensor includes a substrate, a three-dimensional sensing structure, and a single electrode structure. The three-dimensional sensing structure is disposed on the substrate, and the surface of the three-dimensional sensing structure is non-planar. The single electrode structure is disposed on the surface of the three-dimensional sensing structure, and relative humidity is obtained based on the resistance values ​​at both ends of the single electrode structure.

[0010] In a humidity sensor according to another embodiment of the present invention, the three-dimensional sensing structure is a conical structure, a quadrangular pyramid structure, or a pyramid structure.

[0011] In a humidity sensor according to another embodiment of the present invention, a ratio of the thickness of the single electrode structure to the maximum thickness of the three-dimensional sensing structure is less than 1.

[0012] In a humidity sensor according to another embodiment of the present invention, the single electrode structure is a linear electrode, and the water absorption thickness expansion rate of the three-dimensional sensing structure is less than 10%.

[0013] In a humidity sensor according to another embodiment of the present invention, the single electrode structure is a serpentine electrode or a spiral electrode, and the water absorption thickness expansion rate of the three-dimensional sensing structure is between 0% and 10%.

[0014] In the humidity sensor according to various embodiments of the present invention, the single electrode structure and the substrate are not in contact with each other.

[0015] Based on the above, the humidity sensor of the present invention includes a sensing layer or a three-dimensional sensing structure disposed between a substrate and a single electrode structure. By measuring the resistance value of the single electrode structure, the stress change of the sensing layer or the three-dimensional sensing structure can be obtained, and the relative humidity can be obtained. The resistance value of the single electrode structure and the relative humidity are linearly related. Therefore, the resistance value of the single electrode structure does not need to be subjected to a logarithmic operation to obtain the relative humidity, thereby meeting the demand for a resistive humidity sensor with good interchangeability and solving the problem that traditional resistive humidity sensors require a logarithmic operation of the resistance value to obtain the relative humidity.

[0016] In order to make the above features and advantages of the present invention more clearly understood, embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 FIG. 1 is a schematic diagram of the layers of a humidity sensor according to the first embodiment of the present invention.

[0018] Figure 2 FIG. 4 is a schematic diagram of the layers of a humidity sensor according to a second embodiment of the present invention.

[0019] Figure 3FIG. 4 is a schematic diagram of the layers of a humidity sensor according to a third embodiment of the present invention.

[0020] Figure 4 for Figure 3 Schematic cross-section diagram of the AA section line.

[0021] Figure 5 FIG. 4 is a schematic diagram of a layered structure of a humidity sensor according to a fourth embodiment of the present invention.

[0022] Figure 6 for Figure 5 Schematic cross-section diagram of the BB section line.

[0023] Figure 7 FIG. 4 is a schematic diagram of the layers of a humidity sensor according to a fifth embodiment of the present invention.

[0024] Figure 8 FIG. 4 is a schematic diagram of the layers of a humidity sensor according to a sixth embodiment of the present invention.

[0025] Reference numerals:

[0026] 10a, 10b, 20a, 20b, 20c, 20d: Humidity sensors

[0027] 100, 200: substrate

[0028] 110: Sensing layer

[0029] 111, 211: surface

[0030] 120, 220: Single electrode structure

[0031] 210: Stereoscopic Sensing Structure

[0032] AA, BB: hatching

[0033] t1, t2, t3, t4: thickness

[0034] x, y: direction

[0035] θ: angle DETAILED DESCRIPTION

[0036] Reference will now be made in detail to exemplary embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Whenever possible, like reference numerals are used in the drawings and the description to refer to like or similar parts. Furthermore, the drawings are for illustrative purposes only and are not drawn to scale. For ease of understanding, like components will be designated by like reference numerals throughout the following description.

[0037] In addition, the terms "include", "including", "have", etc. used in this document are open terms, which means "including but not limited to".

[0038] It should be understood that although the terms "first," "second," "third," etc., may be used herein to describe various devices, components, regions, layers, and / or portions, these devices, components, regions, and / or portions should not be limited by these terms. These terms are only used to distinguish one device, component, region, layer, or portion from another device, component, region, layer, or portion. Thus, a "first device," "component," "region," "layer," or "portion" discussed below may be referred to as a second device, component, region, layer, or portion without departing from the teachings herein.

[0039] In addition, directional terms mentioned herein, such as “upper” and “lower”, are only used to refer to the directions of the drawings and are not intended to limit the present invention.

[0040] Figure 1 FIG. 1 is a schematic diagram of the layers of a humidity sensor according to the first embodiment of the present invention.

[0041] Please refer to Figure 1 The humidity sensor 10a includes a substrate 100, a sensing layer 110, and a single electrode structure 120. The substrate 100 may be a rigid substrate or a flexible substrate, but the present invention is not limited thereto. The sensing layer 110 is disposed on the substrate 100, and the single electrode structure 120 is disposed on the surface 111 of the sensing layer 110 and is bonded to the sensing layer 110. The projection of the single electrode structure 120 on the substrate 100 does not exceed the projection of the sensing layer 110 on the substrate 100; in other words, the single electrode structure 120 and the substrate 100 do not contact each other.

[0042] The sensing layer 110 is essentially a planar surface with a uniform thickness t1, and can be formed, for example, by spin coating, dip coating, or other suitable methods. The sensing layer 110 can be made of a water-swelling material whose expansion increases linearly with increasing relative humidity, such as polyimide, sodium polystyrenesulfonate, poly(methyl methacrylate) (PMMA), cellulose acetate-butyrate, benzocyclobutene, or other suitable materials, although the present invention is not limited thereto. The water-swelling rate of the sensing layer 110 can be less than 10% to prevent the single electrode structure 120 from collapsing due to stress exceeding its tolerable range. This prevents irreversible deformation of the single electrode structure 120. Furthermore, the signal variation of the single electrode structure 120 can be relatively stable, preventing excessive resistance changes that could result in significant signal variations. The aforementioned water absorption thickness expansion rate of the sensing layer 110 refers to the thickness expansion rate obtained by converting the mass expansion rate. Specifically, the water absorption thickness expansion rate is obtained by measuring the difference in mass of the material before and after water absorption, that is, the increase in mass caused by water. The density of water can be used to infer the increased volume of the material, and the change in thickness can be calculated from the area of ​​the material to obtain the water absorption thickness expansion rate. Among them, a water absorption thickness expansion rate of 0% represents the water absorption thickness expansion rate in a humidity-free environment.

[0043] The shape of the single electrode structure 120 is not particularly limited, as long as it can sense the deformation of the sensing layer 110 and measure the resistance value of the single electrode structure 120. In the first embodiment, the single electrode structure 120 is a straight electrode extending along the x-direction, but the present invention is not limited to this. In some embodiments, the single electrode structure 120 is a serpentine or spiral electrode. The material of the single electrode structure 120 may include gold, silver, copper, platinum, aluminum, or alloys of the foregoing metals, but the present invention is not limited to this. The single electrode structure 120 has a substantially uniform thickness t2, and can be formed, for example, by screen printing, physical / chemical vapor deposition, or other suitable methods. The thickness t2 of the single electrode structure 120 is less than the thickness t1 of the sensing layer 110, and the ratio of the thickness t2 of the single electrode structure 120 to the thickness t1 of the sensing layer 110 is less than 1.

[0044] Because the sensing layer 110 undergoes linear expansion or contraction changes with changes in relative humidity, and the single electrode structure 120 is in contact with the surface 111 of the sensing layer 110, stress changes occur along with the deformation of the sensing layer 110. By measuring the resistance values ​​at the two endpoints of the single electrode structure 120, the stress changes in the sensing layer 110 can be determined, thereby obtaining the relative humidity. In other words, based on the structure of the humidity sensor 10a of this embodiment, the relative humidity can be obtained based on the resistance values ​​at the two endpoints of the single electrode structure 120, and the relative humidity is linearly related to the resistance values ​​at the two endpoints of the single electrode structure 120. This overcomes the shortcomings of conventional resistance-type humidity sensors, which require logarithmic calculations and have poor interchangeability, while still retaining the advantages of conventional resistance-type humidity sensors, such as fast response speed and low measurement cost. In other words, the humidity sensor 10a of the present invention combines the advantages of both conventional resistance-type humidity sensors and capacitance-type humidity sensors.

[0045] Figure 2 FIG. 4 is a schematic diagram of the layers of a humidity sensor according to a second embodiment of the present invention. Figure 2 The layered diagram is roughly similar to Figure 1 Therefore, the same components in the second embodiment as those in the first embodiment can refer to the aforementioned related contents, so the same configurations in the first and second embodiments will not be repeated here.

[0046] exist Figure 2 The humidity sensor 10b of this embodiment differs from the first embodiment in that its single electrode structure 120 is a serpentine electrode, extending continuously in both the x- and y-directions. The projection of the single electrode structure 120 onto the substrate 100 falls within the projection of the sensing layer 110 onto the substrate 100. Because the single electrode structure 120 is a continuous structure extending in both the x- and y-directions, it can sense two-dimensional stress changes in the sensing layer 110, improving the stress sensitivity and resistance of the humidity sensor 10b. This, in turn, increases the sensitivity of the humidity sensor 10b and facilitates miniaturization.

[0047] Figure 3 FIG. 4 is a schematic diagram of the layers of a humidity sensor according to a third embodiment of the present invention. Figure 4 for Figure 3 Schematic cross-section diagram of the AA section line.

[0048] Please refer to Figure 3The humidity sensor 20a comprises a substrate 200, a three-dimensional sensing structure 210 and a single electrode structure 220. The substrate 200 can be a rigid substrate or a flexible substrate, and the present application is not limited thereto. The three-dimensional sensing structure 210 is disposed on the substrate 100, wherein the surface 211 of the three-dimensional sensing structure 210 is non-planar. The single electrode structure 220 is disposed on the surface 211 of the three-dimensional sensing structure 210 and adheres to the three-dimensional sensing structure 210. The projection range of the single electrode structure 220 on the substrate 200 does not exceed the projection range of the three-dimensional sensing structure 210 on the substrate 200, that is, the single electrode structure 220 and the substrate 200 do not contact each other.

[0049] Please refer to Figure 3 and Figure 4 The three-dimensional sensing structure 210 can be a structure with a relatively thick middle and a relatively thin periphery, such as a conical structure, a quadrangular pyramid structure or a pyramidal structure, and the present application is not limited thereto. Figure 3 The three-dimensional sensing structure 210 is a quadrangular pyramid structure in the embodiment, but the present application is not limited thereto. The three-dimensional sensing structure 210 can be formed by 3D printing, but the present application is not limited thereto. The thickness of the three-dimensional sensing structure 210 refers to the vertical distance from the surface 211 of the three-dimensional sensing structure 210 to the surface of the substrate 200. Figure 4 The included angle between the surface 211 of the three-dimensional sensing structure 210 and the substrate 200 is between 30° and 90° in the embodiment. The material of the three-dimensional sensing structure 210 can be a water-absorbing and swelling material, such as polyimide, sodium polystyrene sulfonate, polymethyl methacrylate, cellulose acetate butyrate (CAB), benzocyclobutene or other suitable materials, and the present application is not limited thereto. The water-absorbing and thickness swelling rate of the three-dimensional sensing structure 210 is less than 10% to avoid the collapse of the single electrode structure 220 beyond its stress range, that is, to avoid irreversible deformation of the single electrode structure 220, and at the same time, the signal change of the single electrode structure 220 can be more stable, that is, there will be no excessive resistance change to cause excessive signal change. The water-absorbing and thickness swelling rate of the three-dimensional sensing structure 210 refers to the thickness swelling rate converted from the mass swelling rate, and further, the water-absorbing and thickness swelling rate is obtained by measuring the mass difference of the material before and after water absorption, that is, the mass increase caused by water, and then the volume increase of the material is obtained through the density of water, and finally the thickness change is obtained through the area of the material, wherein the water-absorbing and thickness swelling rate of 0% indicates the water-absorbing and thickness swelling rate in a humidity-free environment.

[0050] The shape of the single electrode structure 220 is not particularly limited, as long as it can sense the deformation of the three-dimensional sensing structure 210 and measure the resistance value of the single electrode structure 220. Figure 3 In the embodiment, the single electrode structure 220 is a straight electrode extending along the x-direction, but the present invention is not limited thereto. In some embodiments, the single electrode structure 220 can be a serpentine or spiral electrode. The material of the single electrode structure 220 can include gold, silver, copper, platinum, aluminum, or alloys of the foregoing metals, but the present invention is not limited thereto. The single electrode structure 220 has a substantially uniform thickness t4, and can be formed, for example, by screen printing, physical / chemical vapor deposition, or other suitable methods. The thickness t4 of the single electrode structure 220 is less than the maximum thickness t3 of the three-dimensional sensing structure 210, and the ratio of the thickness t4 of the single electrode structure 220 to the maximum thickness t3 of the three-dimensional sensing structure 210 is less than 1.

[0051] Because the three-dimensional sensing structure 210 undergoes linear expansion or contraction with changes in relative humidity, and the single electrode structure 220, in contact with the surface 211 of the three-dimensional sensing structure 210, produces stress changes along with the deformation of the three-dimensional sensing structure 210, the stress changes in the sensing layer 210 can be determined by measuring the resistance values ​​at the two endpoints of the single electrode structure 220, thereby obtaining the relative humidity. In other words, based on the structure of the humidity sensor 20a of this embodiment, the relative humidity can be obtained based on the resistance values ​​at the two endpoints of the single electrode structure 220. The relative humidity and the resistance values ​​at the two endpoints of the single electrode structure 220 are linearly related. This overcomes the shortcomings of traditional resistance-type hygrometers, which require logarithmic calculations and have poor interchangeability, while still retaining the advantages of traditional resistance-type hygrometers, such as fast response speed and low measurement cost. Furthermore, because the thickness of the three-dimensional sensing structure 210 is not uniform, the single electrode structure 220 can sense stress changes in the three-dimensional sensing structure 210 in both the x- and z-directions, improving stress sensing and increasing the sensitivity of the humidity sensor 20a.

[0052] Figure 5 FIG. 4 is a schematic diagram of a layered structure of a humidity sensor according to a fourth embodiment of the present invention. Figure 5 The layered diagram is roughly similar to Figure 3 Therefore, the same components in the fourth embodiment as those in the third embodiment can refer to the aforementioned related contents, so the same configurations in the third and fourth embodiments will not be repeated here. Figure 6 for Figure 5 Schematic cross-section diagram of the BB section line.

[0053] exist Figure 5 as well as Figure 6The humidity sensor 20b of this embodiment differs from the third embodiment in that the single electrode structure 220 of the humidity sensor 20b is a serpentine electrode with a continuous structure extending in both the x- and y-directions. The thickness expansion rate of the three-dimensional sensing structure 210 due to water absorption can be between 0% and 10%, thereby preventing irreversible deformation of the single electrode structure 220. Furthermore, the signal variation of the single electrode structure 220 is relatively stable, i.e., it does not experience excessive resistance changes that could cause excessive signal variations. Because the single electrode structure 220 is a continuous structure extending in both the x- and y-directions and the three-dimensional sensing structure 210 has a non-uniform thickness, the single electrode structure 220 can sense three-dimensional stress variations in the three-dimensional sensing structure 210, thereby improving the stress sensing performance of the humidity sensor 20b and increasing its resistance. This, in turn, enhances the sensitivity of the humidity sensor 20b and facilitates miniaturization.

[0054] Figure 7 FIG. 4 is a schematic diagram of the layers of a humidity sensor according to a fifth embodiment of the present invention. Figure 7 The layered diagram is roughly similar to Figure 3 Therefore, the same components in the fifth embodiment as those in the third embodiment can refer to the aforementioned related contents, so the same configurations in the third and fifth embodiments will not be repeated here.

[0055] exist Figure 7 The humidity sensor 20c of this embodiment is different from the third embodiment in that the three-dimensional sensing structure 210 of the humidity sensor 20c is a conical structure, and the single electrode structure 220 is attached to the surface 211 of the three-dimensional sensing structure 210, similar to Figure 4 As shown in the cross-sectional view, the projection of the single electrode structure 220 on the substrate 200 does not exceed the projection of the 3D sensing structure 210 on the substrate 200. Because the 3D sensing structure 210 has a non-uniform thickness, the single electrode structure 220 can sense stress changes in the 3D sensing structure 210 in the x- and z-directions, improving stress sensing and increasing the sensitivity of the humidity sensor 20c.

[0056] Figure 8 FIG. 4 is a schematic diagram of the layers of a humidity sensor according to a sixth embodiment of the present invention. Figure 8 The layered diagram is roughly similar to Figure 7 Therefore, the same components described in the sixth embodiment can refer to the aforementioned content, and the same configurations as those in the fifth and sixth embodiments will not be repeated here.

[0057] exist Figure 8The humidity sensor 20d of this embodiment is different from the fifth embodiment in that the single electrode structure 220 of the humidity sensor 20d is a spiral electrode that surrounds the three-dimensional sensing structure 210 in a counterclockwise or clockwise direction and is attached to the surface 211 of the three-dimensional sensing structure 210, similar to Figure 6 As shown in the cross-sectional view. The projection range of the single electrode structure 220 on the substrate 200 does not exceed the projection range of the three-dimensional sensing structure 210 on the substrate 200. Since the single electrode structure 220 is a spiral continuous structure and the thickness of the three-dimensional sensing structure 210 is not a single thickness, the single electrode structure 220 can sense the three-dimensional stress changes of the three-dimensional sensing structure 210, thereby improving the stress sensing of the humidity sensor 20d and increasing the resistance, thereby improving the sensitivity of the humidity sensor 20d and facilitating miniaturization. The water absorption thickness expansion rate of the three-dimensional sensing structure 210 can also be between 0% and 10% to avoid causing irreversible deformation of the single electrode structure 220. At the same time, the signal change of the single electrode structure 220 can be relatively stable, that is, there will be no excessive resistance change that causes excessive signal change.

[0058] In summary, the humidity sensor of the present invention includes a sensing layer or a three-dimensional sensing structure disposed between a substrate and a single electrode structure. By measuring the resistance value of the single electrode structure, the stress change of the sensing layer or the three-dimensional sensing structure can be obtained, and the relative humidity can be obtained. The resistance value of the single electrode structure and the relative humidity are linearly related. Therefore, the resistance value of the single electrode structure does not need to be subjected to a logarithmic calculation to obtain the relative humidity. This meets the demand for a resistive humidity sensor with high interchangeability and solves the problem of traditional resistive humidity sensors requiring a logarithmic calculation of the resistance value to obtain the relative humidity. While retaining the advantages of traditional resistive humidity sensors such as fast response speed and low measurement cost.

[0059] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A humidity sensor, characterized in that: include: substrate; a sensing layer disposed on the substrate and in direct contact with the substrate, wherein the sensing layer expands or contracts linearly with changes in relative humidity; as well as A single electrode structure is disposed on the surface of the sensing layer, wherein the ratio of the thickness of the single electrode structure to the thickness of the sensing layer is less than 1, and the single electrode structure is in contact with the surface of the sensing layer. The stress change of the sensing layer is obtained based on the resistance values ​​at the two end points of the single electrode structure, thereby obtaining the relative humidity, wherein the relative humidity is linearly related to the resistance values ​​at the two end points of the single electrode structure.

2. The humidity sensor according to claim 1, characterized in that The single electrode structure is a linear electrode, and the water absorption thickness expansion rate of the sensing layer is less than 10%.

3. The humidity sensor according to claim 1, wherein The single electrode structure is a serpentine electrode or a spiral electrode, and the water absorption thickness expansion rate of the sensing layer is between 0% and 10%.

4. A humidity sensor, characterized in that: include: substrate; a three-dimensional sensing structure disposed on the substrate and in direct contact with the substrate, wherein the surface of the three-dimensional sensing structure is non-planar, and wherein the expansion degree of the three-dimensional sensing structure increases linearly with increasing relative humidity; as well as A single electrode structure is arranged on the surface of the three-dimensional sensing structure, the ratio of the thickness of the single electrode structure to the maximum thickness of the three-dimensional sensing structure is less than 1, and the single electrode structure is in contact with the surface of the three-dimensional sensing structure. The stress change of the three-dimensional sensing structure is obtained based on the resistance values ​​of the two end points of the single electrode structure, and the relative humidity is obtained, wherein the relative humidity is linearly related to the resistance values ​​of the two end points of the single electrode structure.

5. The humidity sensor according to claim 4, characterized in that The three-dimensional sensing structure is a cone structure, a quadrangular pyramid structure or a pyramid structure.

6. The humidity sensor according to claim 4, characterized in that The single electrode structure is a linear electrode, and the water absorption thickness expansion rate of the three-dimensional sensing structure is less than 10%.

7. The humidity sensor according to claim 4, characterized in that The single electrode structure is a serpentine electrode or a spiral electrode, and the water absorption thickness expansion rate of the three-dimensional sensing structure is between 0% and 10%.

8. The humidity sensor according to claim 1 or 4, characterized in that: The single electrode structure and the substrate are not in contact with each other.

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