Visual humidity sensor based on alternating current electroluminescence and preparation method

Abstract

The invention relates to the technical field of humidity sensors, and discloses a visual humidity sensor based on alternating-current electroluminescence, which comprises a base layer and a humidity-sensitive luminescent layer, a coplanar dual-electrode layer is arranged between the base layer and the humidity-sensitive luminescent layer, the humidity-sensitive luminescent layer is coated on the surface of the coplanar dual-electrode layer, and the humidity-sensitive luminescent layer is coated on the surface of the coplanar dual-electrode layer. Two electrodes of the coplanar dual-electrode layer are located on the same plane and are closely adjacent, the thickness of the two electrodes of the coplanar dual-electrode layer is 20 nm to 20 [mu] m, and the two electrodes of the coplanar dual-electrode layer are made of any one or a combination of more of metal, transparent conductive oxide, a nano conductive material, ionic conductive gel and a conductive polymer material; according to the humidity sensor, humidity sensing is achieved through luminous intensity changes caused by capacitance and impedance changes before and after moisture absorption, the luminous intensity changes before and after moisture absorption, and the luminous brightness is reduced along with increase of humidity.

Description

Technical Field

[0001] The present invention relates to the technical field of humidity sensors, and specifically to a visualization humidity sensor based on alternating current electroluminescence and a preparation method thereof. Background Art

[0002] A humidity sensor is a device that can sense and measure the environmental humidity level and convert it into a measurable signal. Generally, it can be divided into: resistive humidity sensor, capacitive humidity sensor, thermistor humidity sensor, dew point humidity sensor, optical humidity sensor, semiconductor humidity sensor, electrochemistry humidity sensor, and so on.

[0003] Traditional humidity sensor devices adopt a sandwich electrode structure, which is not conducive to the penetration of water vapor. At the same time, during the repeated charge and discharge process of the sandwich electrode plate, the cycle stability may decrease due to problems such as interface stress and material expansion. Some active materials have a large volume change during the charge and discharge process, and the volume effect of the active substance may cause damage to the electrode structure. Therefore, a visualization humidity sensor based on alternating current electroluminescence and a preparation method thereof are proposed to solve the above problems. Summary of the Invention

[0004] In view of the deficiencies of the prior art, the present invention provides a visualization humidity sensor based on alternating current electroluminescence and a preparation method thereof, which have the advantages of simple production, simple structure, high sensitivity, etc., and solve the problems mentioned in the above background art.

[0005] To achieve the above object, the present invention provides the following technical solution: A visualization humidity sensor based on alternating current electroluminescence, including a base layer and a humidity-sensitive light-emitting layer. A coplanar double electrode layer is provided between the base layer and the humidity-sensitive light-emitting layer, and the humidity-sensitive light-emitting layer is coated on the surface of the coplanar double electrode layer.

[0006] Preferably, the two electrodes of the coplanar double electrode layer are in the same plane, the electrode interval is 50 μm - 2 mm, and the thickness of the two electrodes of the coplanar double electrode layer is 20 nm - 20 μm.

[0007] Preferably, the two electrode materials of the coplanar double electrode layer are any one or a combination of metals, transparent conductive oxides, nano-conductive materials, ion conductive gels, and conductive polymer materials.

[0008] Preferably, the humidity-sensitive light-emitting layer is formed by uniformly mixing and curing a light-emitting material and a hydrogel, and the thickness of the humidity-sensitive light-emitting layer is 10 μm - 200 μm.

[0009] Preferably, the light-emitting material is alternating current electroluminescence phosphor, SrAl2O4 light-emitting material, Eu 2+Luminescent materials and any one or more combinations of various zinc sulfide-doped luminescent materials.

[0010] Preferably, the hydrogel is a humidity-sensitive hydrogel, including any one or more combinations of polyvinyl alcohol, polyacrylamide, sodium polyacrylate, acrylate polymer, and cellulose hydrogel.

[0011] Preferably, the specific steps are as follows: S1: Select a base layer with a suitable size, and form a coplanar double-electrode layer by copper plating on the surface of the base layer using a suitable process; S2: Mix the luminescent material and the hydrogel according to a certain weight ratio; S3: Uniformly coat the mixed material on the coplanar double-electrode layer to form a humidity-sensitive luminescent layer; S4: Place the humidity sensor on a hot stage at 60 - 120 °C and cure for 15 min - 3 h; S5: Weld copper wires to the two electrodes of the coplanar double-electrode layer respectively, and connect to the output end of an AC high-voltage power supply driver.

[0012] Preferably, the ratio of the luminescent material to the hydrogel is 7:3.

[0013] Preferably, the optimal temperature of the hot stage is 80 °C, and the optimal curing time is 1 h.

[0014] Compared with the prior art, the present invention provides a visualization humidity sensor based on alternating current electroluminescence and a preparation method, having the following beneficial effects: 1. For the visualization humidity sensor based on alternating current electroluminescence, the change in luminescence intensity caused by the change in capacitance and impedance before and after moisture absorption is used to sense humidity. The luminescence intensity changes before and after moisture absorption, and the luminescence brightness decreases with the increase in humidity.

[0015] 2. For the visualization humidity sensor based on alternating current electroluminescence, by adopting a coplanar double-electrode structure, it is beneficial for the humidity-sensitive luminescent layer to be in full contact with air. At the same time, taking advantage of the strong moisture absorption characteristics of the hydrogel, the humidity sensing sensitivity is high. The hydrogel and the electroluminescent material are compounded into a humidity-sensitive luminescent layer, which has the characteristic of simple process. When the hydrogel absorbs water and swells, the capacitance increases, the resistance decreases accordingly, and the luminescence brightness weakens. Different from existing humidity sensors, it is based on different visualization humidity sensing mechanisms and presents different luminescence effects. Description of the Drawings

[0016] Figure 1 It is a schematic structural diagram of a visualization humidity sensor based on alternating current electroluminescence proposed by the present invention; Figure 2A luminescence spectrum diagram of a visualization humidity sensor based on alternating current electroluminescence proposed by the present invention; Figure 3 A schematic diagram of a humidity sensor with a printed circuit board as the substrate in the first embodiment of the present invention; Figure 4 A schematic diagram of a spiral coplanar double - electrode structure in the third embodiment of the present invention; Figure 5 A schematic diagram of the humidity sensor emitting light after being powered on in the third embodiment of the present invention.

[0017] In the figure: 1 base layer, 2 coplanar double - electrode layer, 3 humidity - sensitive luminescent layer. Specific embodiments

[0018] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0019] Embodiment 1: Please refer to Figures 1-3 , a visualization humidity sensor based on alternating current electroluminescence, including a base layer 1 and a humidity - sensitive luminescent layer 3. A coplanar double - electrode layer 2 is arranged between the base layer 1 and the humidity - sensitive luminescent layer 3, and the humidity - sensitive luminescent layer 3 is coated on the surface of the coplanar double - electrode layer 2.

[0020] The two electrodes of the coplanar double - electrode layer 2 are in the same plane, the electrode interval is 50 μm - 2 mm, and the thickness of the two electrodes of the coplanar double - electrode layer 2 is 20 nm - 20 μm.

[0021] The materials of the two electrodes of the coplanar double - electrode layer 2 are any one of metals, transparent conductive oxides, nano - conductive materials, ion - conductive gels, and conductive polymer materials.

[0022] The humidity - sensitive luminescent layer 3 is formed by uniformly mixing and curing a luminescent material and a hydrogel, and the thickness of the humidity - sensitive luminescent layer 3 is 10 μm - 200 μm.

[0023] The luminescent material is any one of alternating current electroluminescence phosphors, SrAl2O4 luminescent materials, Eu 2+ luminescent materials, and various zinc - sulfide - doped luminescent materials.

[0024] The hydrogel is a humidity - sensitive hydrogel, including any one of polyvinyl alcohol, polyacrylamide, sodium polyacrylate, acrylate polymers, and cellulose hydrogels.

[0025] A preparation method of a visualization humidity sensor based on alternating current electroluminescence, the specific steps are as follows: S1: Select a printed circuit board with a size of 6 cm × 3 cm × 1 mm as the base layer 1, and use the copper plating process to prepare a copper layer with a thickness of 35 μm on the surface of the base layer 1 to form a coplanar double electrode layer 2; S2: Mix the luminescent material and the hydrogel according to a weight ratio of 7:3, and select copper-doped zinc sulfide phosphor as the luminescent material; S3: Uniformly coat the mixed material on the coplanar double electrode layer 2 to form a humidity-sensitive luminescent layer 3 with a thickness of 40 μm; S4: Place the humidity sensor on a hot stage at 80 °C and cure for 1 h; S5: Weld copper wires to the two electrodes of the coplanar double electrode layer 2 respectively, and connect the output end of the AC high-voltage power supply driver.

[0026] Start the AC high-voltage power supply, and the humidity-sensitive luminescent layer 3 emits visible light in the area between the coplanar double electrodes. As the ambient humidity changes, the capacitance of the humidity-sensitive luminescent layer 3 changes, and the emitted light brightness changes simultaneously.

[0027] Humidity sensing process: When the humidity is 15%, the luminescence brightness is high; as the humidity gradually increases, the luminescence brightness gradually decreases; when the humidity decreases again, the luminescence brightness gradually increases again. Align the fiber optic spectrometer with the luminescent area and measure the spectrum as Figure 2 shown, the luminescence peak is located at 477 nm, in the visible blue light region.

[0028] In summary, for this visualization humidity sensor based on alternating current electroluminescence, the humidity sensing is realized by the change of the luminescence intensity caused by the change of capacitance and impedance before and after moisture absorption. The luminescence intensity changes before and after moisture absorption, and the luminescence brightness decreases with the increase of humidity.

[0029] Moreover, by adopting a coplanar double electrode structure, it is beneficial for the humidity-sensitive luminescent layer 3 to be in full contact with the air. At the same time, taking advantage of the strong hygroscopicity of the hydrogel, the humidity sensing sensitivity is high. The hydrogel and the electroluminescent material are compounded into the humidity-sensitive luminescent layer 3, which has the characteristics of simple process. When the hydrogel absorbs water and swells, the capacitance increases, the resistance decreases accordingly, and the luminescence brightness weakens. It is based on a different visualization humidity sensing mechanism from the existing humidity sensors and presents different luminescence effects.

[0030] Example two: Please refer to Figures 1-2 , a preparation method of a visualization humidity sensor based on alternating current electroluminescence, the specific steps are as follows: S1: Select a quartz glass plate with dimensions of 15 mm × 20 mm × 1.1 mm as the base layer 1, and prepare a transparent interdigital ITO double electrode layer with a thickness of 200 nm through a magnetron sputtering process to form a coplanar double electrode layer 2, with a line width of 80 μm, a finger length of 8.5 mm, and 30 finger pairs of interdigital electrodes; S2: Mix the luminescent material and the hydrogel in a weight ratio of 7:3. The luminescent material is selected as copper-doped zinc sulfide phosphor; S3: Uniformly coat the mixed material on the coplanar double electrode layer 2 to form a humidity-sensitive luminescent layer 3 with a thickness of 40 μm; S4: Place the humidity sensor on a hot plate at 80 °C and cure for 1 h; S5: Weld copper wires to the two electrodes of the coplanar double electrode layer 2 respectively, and connect to the output terminal of an AC high-voltage power supply driver.

[0031] After turning on an AC power supply of 200 V and 1 kHz, the luminescence phenomenon can be observed. When the humidity changes, the luminescence intensity changes. When the humidity increases, the luminescence intensity decreases; when the humidity decreases, the luminescence intensity increases.

[0032] In summary, for this visual humidity sensor based on AC electroluminescence, the change in luminescence intensity caused by the change in capacitance and impedance before and after moisture absorption realizes the sensing of humidity. The luminescence intensity changes before and after moisture absorption, and the luminescence brightness decreases with the increase in humidity.

[0033] Moreover, by adopting a coplanar double electrode structure, it is beneficial for the humidity-sensitive luminescent layer 3 to be in full contact with air. At the same time, taking advantage of the strong hygroscopicity of the hydrogel, the humidity sensing sensitivity is high. The hydrogel and the electroluminescent material are compounded into the humidity-sensitive luminescent layer 3, which has the characteristic of simple process. When the hydrogel absorbs water and swells, the capacitance increases and the resistance decreases accordingly, and the luminescence brightness weakens. Different from existing humidity sensors, it is based on different visual humidity sensing mechanisms and presents different luminescence effects.

[0034] Example 3: Please refer to Figure 1 、 2 Figures 4 and 5, a preparation method of a visual humidity sensor based on AC electroluminescence, the specific steps are as follows: S1: Select a polyimide with dimensions of 11.6 mm × 16.2 mm × 1 mm as the base layer 1, and prepare a metal electrode layer with a thickness of 13 μm through the copper plating process of a printed circuit board. The metal can be Cu, Au, or Ni, to form a coplanar double electrode layer 2, with a line width of 100 μm and a line pitch of 100 μm; S2: Mix the luminescent material and the hydrogel in a weight ratio of 7:3. The luminescent material is selected as copper-doped zinc sulfide phosphor; S3: Uniformly coat the mixed materials on the coplanar double - electrode layer 2 to form a humidity - sensitive light - emitting layer 3 with a thickness of 40 μm; S4: Place the humidity sensor on a hot stage at 80 °C and cure for 1 h; S5: Weld copper wires to the two electrodes of the coplanar double - electrode layer 2 respectively and connect to the output terminals of an AC high - voltage power supply driver.

[0035] After turning on an AC power supply of 200 V and 1 kHz, the light - emitting phenomenon can be observed. When the humidity changes, the light - emitting intensity changes. As the humidity increases, the light - emitting intensity decreases; as the humidity decreases, the light - emitting intensity increases.

[0036] In summary, for this visual humidity sensor based on AC electroluminescence, the change in capacitance and impedance before and after moisture absorption causes a change in light - emitting intensity to achieve humidity sensing. The light - emitting intensity changes before and after moisture absorption, and the light - emitting brightness decreases as the humidity increases.

[0037] Moreover, by adopting a coplanar double - electrode structure, it is beneficial for the humidity - sensitive light - emitting layer 3 to be in full contact with air. At the same time, taking advantage of the strong hygroscopicity of the hydrogel, the humidity sensing sensitivity is high. The hydrogel and the electroluminescent material are compounded into the humidity - sensitive light - emitting layer 3, which has the characteristic of simple process. When the hydrogel absorbs water and swells, the capacitance increases and the resistance decreases accordingly, and the light - emitting brightness weakens. It is based on a different visual humidity sensing mechanism from existing humidity sensors and presents different light - emitting effects.

[0038] It should be noted that the term "including", "comprising" or any other variant thereof is intended to cover non - exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "including a..." does not exclude the existence of additional identical elements in the process, method, article or device including said element.

[0039] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A visual humidity sensor based on AC electroluminescence, characterized in that: It comprises a base layer (1) and a humidity-sensitive luminescent layer (3), wherein a coplanar double electrode layer (2) is arranged between the base layer (1) and the humidity-sensitive luminescent layer (3), and the humidity-sensitive luminescent layer (3) is coated on the surface of the coplanar double electrode layer (2).

2. The visual humidity sensor based on AC electroluminescence according to claim 1, characterized in that: The two electrodes of the coplanar double electrode layer (2) are located in the same plane, the electrode spacing is 50 μm-2 mm, and the thickness of the two electrodes of the coplanar double electrode layer (2) is 20 nm-20 μm.

3. The visual humidity sensor based on AC electroluminescence according to claim 1, characterized in that: The two electrodes of the coplanar double electrode layer (2) are made of any one or more combinations of metal, transparent conductive oxide, nano conductive material, ion conductive gel and conductive polymer material.

4. The visual humidity sensor based on AC electroluminescence according to claim 1, characterized in that: The humidity sensitive luminescent layer (3) is formed by uniformly mixing and solidifying a luminescent material and a hydrogel, and the humidity sensitive luminescent layer (3) has a thickness of 10 μm-200 μm.

5. The visual humidity sensor based on AC electroluminescence according to claim 4, characterized in that: The luminescent material is AC electroluminescent phosphor, SrAl2O4 luminescent material, Eu 2+ Luminescent material and any one or more combinations of various zinc sulfide-doped luminescent materials.

6. The visual humidity sensor based on AC electroluminescence according to claim 4, characterized in that: The hydrogel is a humidity sensitive hydrogel, including any one or more combinations of polyvinyl alcohol, polyacrylamide, sodium polyacrylate, acrylate polymer, and cellulose hydrogel.

7. A method for preparing a visualized humidity sensor based on AC electroluminescence according to any one of claims 1 to 6, characterized in that: The specific steps are: S1: Select a base layer (1) of suitable size, and use a suitable process to coat copper on the surface of the base layer (1) to form a coplanar double electrode layer (2); S2: mixing the luminescent material and the hydrogel in a certain weight ratio; S3: uniformly coating the mixed material on the coplanar double electrode layer (2) to form a humidity-sensitive light-emitting layer (3); S4: Place the humidity sensor on a hot plate at 60-120°C and cure for 15min-3h; S5: Weld copper wires onto the two electrodes of the coplanar double electrode layer (2) respectively, and connect them to the output end of the AC high voltage power driver.

8. The method for preparing a visual humidity sensor based on AC electroluminescence according to claim 7, characterized in that The optimal ratio of the luminescent material to the hydrogel is 7:

3.

9. The method for preparing a visual humidity sensor based on AC electroluminescence according to claim 7, characterized in that The optimal temperature of the hot stage is 80°C, and the optimal curing time is 1h.

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