阅读说明：本技术 一种湿敏组合物、柔性湿度传感器及其制备方法 (Humidity-sensitive composition, flexible humidity sensor and preparation method thereof ) 是由 魏迪 杨飞要 于 2019-10-17 设计创作，主要内容包括：本发明一实施方式提供了一种湿敏组合物、柔性湿度传感器及其制备方法,所述湿敏组合物包括氧化石墨烯和保护剂,其中,所述保护剂包括极性聚合物。本发明一实施方式的湿敏组合物,可用作湿度传感器的湿敏材料,具有良好的湿敏特性和稳定性。(An embodiment of the invention provides a humidity-sensitive composition, a flexible humidity sensor and a preparation method thereof, wherein the humidity-sensitive composition comprises graphene oxide and a protective agent, and the protective agent comprises a polar polymer. The humidity-sensitive composition provided by the embodiment of the invention can be used as a humidity-sensitive material of a humidity sensor, and has good humidity-sensitive characteristics and stability.)

1. A moisture-sensitive composition comprising graphene oxide and a protectant, wherein the protectant comprises a polar polymer.

2. The moisture-sensitive composition according to claim 1, wherein the protective agent is selected from one or more of aqueous polyurethane, aqueous vinyl chloride-vinyl acetate resin, aqueous saturated polyester resin, alkyd resin, and polyamide resin.

3. The moisture-sensitive composition according to claim 1, comprising 0.01 to 1 wt% of the graphene oxide and 0.1 to 20 wt% of the protective agent.

4. The moisture-sensitive composition of claim 1, comprising one or more of a thickener, a surfactant, and a solvent.

5. The moisture-sensitive composition according to claim 4, wherein the thickener comprises an associative polyurethane; the surfactant is selected from one or more of polyoxyethylene ether methacrylate, polyoxyethylene ether acrylate, polyoxypropylene ether acrylate, fatty acid polyglycol ester, polyol ester and fatty amine polyoxyethylene ether; the solvent is selected from one or more of water, ethanol, acetone, butanone, ethyl acetate, ethylene glycol and n-propanol.

6. A flexible humidity sensor comprising a humidity sensitive layer made from the humidity sensitive composition of any one of claims 1 to 5.

7. The flexible humidity sensor according to claim 6, comprising:

a flexible substrate;

the conducting layer is arranged on the flexible substrate, and at least one channel is formed in the conducting layer; and

the humidity sensitive layer is arranged on the conductive layer.

8. A method of manufacturing a flexible humidity sensor according to claim 6 or 7 comprising the steps of printing the conductive layer and the humidity sensitive layer.

9. The method of claim 8, comprising:

cleaning the flexible substrate;

printing a conductive layer and a connecting lead on the flexible substrate by using conductive paste in a printing mode; and

printing the humidity sensitive layer on the conductive layer by adopting a printing mode;

wherein the cleaning treatment is selected from one or more of chemical treatment, photochemical treatment, plasma treatment, corona treatment and antistatic treatment.

10. The method of claim 8 or 9, wherein the preparing of the moisture sensitive layer comprises:

providing a graphene oxide dispersion liquid, wherein the graphene oxide dispersion liquid comprises graphene oxide, a surfactant and a solvent; and

adding a protective agent, a thickening agent and the balance of a solvent into the graphene oxide dispersion liquid, heating, dispersing and dissolving until graphene oxide slurry is formed, filtering, and printing to obtain the humidity-sensitive layer; wherein the heating temperature is 40-100 ℃.

Technical Field

The invention relates to a humidity sensor, in particular to a humidity-sensitive composition for the humidity sensor, a humidity sensor containing the humidity-sensitive composition and a preparation method thereof.

Background

The humidity is closely related to the life and industrial activities of people, and the level of the humidity not only directly affects the comfort degree of people, but also has great influence on biological medicine products, food storage and the like. Generally, the content of moisture in the atmospheric environment can be measured by absolute humidity, relative humidity and specific humidity. Humidity sensors typically measure the relative humidity under certain temperature conditions.

At present, the humidity sensing method mainly achieves the aim of sensing humidity by measuring the resistance change of a humidity sensitive material. The existing humidity sensor is generally made of rigid materials such as metal or silicon, so that the humidity sensor is expensive and does not have the characteristic of bending deformation, and the application range of the humidity sensor is greatly reduced.

Graphene is a two-dimensional thin film material formed by arranging single-layer carbon atoms according to a hexagonal symmetric honeycomb structure. Due to the excellent properties of graphene in electrical, optical, thermal, and mechanical aspects, graphene has attracted much attention in various fields such as physics, chemistry, biology, and materials since its discovery. Graphene Oxide (GO) as the most important derivative of graphene has many characteristics of graphene, and meanwhile, rich polar oxygen-containing functional groups such as hydroxyl groups, epoxy groups and edge carboxyl groups on the surface of graphene enable graphene to have good hydrophilic characteristics, can be stably dispersed in aqueous solution or organic solvent, has good hygroscopicity, and is an ideal non-toxic and harmless humidity sensitive material.

However, the existing method for manufacturing the humidity sensor by using the graphene oxide has complex process or the stability and effectiveness of the sensor cannot be guaranteed, and particularly, the sensor gradually fails after being exposed to the atmospheric environment for a long time. Therefore, stability is one of the key issues to be solved for the graphene oxide humidity sensor.

Disclosure of Invention

It is a primary object of the present invention to provide a moisture-sensitive composition comprising graphene oxide and a protective agent, wherein the protective agent comprises a polar polymer.

According to an embodiment of the present invention, the protective agent is selected from one or more of waterborne polyurethane, waterborne vinyl chloride-vinyl acetate resin, waterborne saturated polyester resin, alkyd resin and polyamide resin.

According to an embodiment of the present invention, the moisture-sensitive composition includes 0.01 to 1 wt% of the graphene oxide and 0.1 to 20 wt% of the protective agent.

According to an embodiment of the invention, the moisture sensitive composition comprises one or more of a thickener, a surfactant and a solvent.

According to an embodiment of the invention, the thickener comprises an associative polyurethane; the surfactant is selected from one or more of polyoxyethylene ether methacrylate, polyoxyethylene ether acrylate, polyoxypropylene ether acrylate, fatty acid polyglycol ester, polyol ester and fatty amine polyoxyethylene ether; the solvent is selected from one or more of water, ethanol, acetone, butanone, ethyl acetate, ethylene glycol and n-propanol.

One embodiment of the present invention provides a flexible humidity sensor comprising a humidity-sensitive layer made from the above humidity-sensitive composition.

According to an embodiment of the invention, the flexible humidity sensor comprises:

a flexible substrate;

a conductive layer disposed on the flexible substrate, the conductive layer having at least one channel formed thereon, an

The humidity sensitive layer is arranged on the conductive layer.

An embodiment of the invention provides a method for manufacturing the flexible humidity sensor as claimed above, which includes the steps of preparing the conductive layer and the humidity-sensitive layer by printing.

According to an embodiment of the invention, the method comprises:

cleaning the flexible substrate;

printing a conductive layer on the flexible substrate by using conductive paste in a printing mode; and

printing the humidity sensitive layer on the conductive layer by adopting a printing mode;

wherein the cleaning treatment is selected from one or more of chemical treatment, photochemical treatment, plasma treatment, corona treatment and antistatic treatment.

According to an embodiment of the present invention, the preparation of the moisture sensitive layer comprises:

mixing graphene oxide, a surfactant and a solvent, and carrying out ultrasonic treatment to obtain a graphene oxide dispersion liquid; and

adding a protective agent, a thickening agent and the balance of a solvent into the graphene oxide dispersion liquid, heating, dispersing and dissolving until graphene oxide slurry is formed, filtering, and printing to obtain the humidity-sensitive layer; wherein the heating temperature is 40-100 ℃.

The humidity-sensitive composition provided by the embodiment of the invention can be used as a humidity-sensitive material of a humidity sensor, and has good humidity-sensitive characteristics and stability.

Drawings

FIG. 1 is a schematic structural view of a humidity sensor according to an embodiment of the present invention;

FIG. 2 is a top view of the moisture-sensitive sensor of FIG. 1 without the moisture-sensitive layer;

FIG. 3 is a schematic structural diagram of a conductive layer according to an embodiment of the present invention;

FIG. 4 is a schematic view of a terminal of a membrane connector according to an embodiment of the present invention;

FIG. 5 is a schematic diagram of a batch printing structure of conductive layers and connecting leads according to an embodiment of the present invention;

FIG. 6 is a schematic structural view of a batch printing of a moisture sensitive layer according to an embodiment of the present invention;

FIG. 7A is a humidity-sensitive characteristic test chart of the humidity sensor manufactured in example 1 of the present invention;

FIG. 7B is a stability test chart of the humidity sensor manufactured in example 1 of the present invention;

FIG. 8A is a humidity-sensitive characteristic test chart of the humidity sensor manufactured in example 2 of the present invention;

FIG. 8B is a stability test chart of the humidity sensor manufactured in example 2 of the present invention;

FIG. 9A is a humidity-sensitive characteristic test chart of the humidity sensor manufactured in example 3 of the present invention;

FIG. 9B is a stability test chart of the humidity sensor manufactured in example 3 of the present invention;

FIG. 10A is a humidity-sensitive characteristic test chart of the humidity sensor manufactured in example 4 of the present invention;

FIG. 10B is a stability test chart of the humidity sensor manufactured in example 4 of the present invention;

FIG. 11A is a humidity-sensitive characteristic test chart of the humidity sensor manufactured in example 5 of the present invention;

FIG. 11B is a stability test chart of the humidity sensor manufactured in example 5 of the present invention;

FIG. 12 is a stability test chart of the humidity sensor manufactured according to the comparative example of the present invention.

Detailed Description

Exemplary embodiments that embody features and advantages of the invention are described in detail below in the specification. It is to be understood that the invention is capable of other embodiments and that various changes in form and details may be made therein without departing from the scope of the invention and the description and drawings are to be regarded as illustrative in nature and not as restrictive.

One embodiment of the present invention provides a moisture-sensitive composition comprising graphene oxide and a protective agent, which may be a polar polymer, particularly a hydrophilic polymer, having affinity or compatibility with a hydroxyl group, an epoxy group, a carboxyl group, etc. of graphene oxide.

In one embodiment, the protective agent may be one or more of waterborne polyurethane, waterborne vinyl chloride-vinyl acetate resin, waterborne saturated polyester resin, alkyd resin and polyamide resin.

In one embodiment, the moisture-sensitive composition comprises 0.01 to 1 wt% of graphene oxide and 0.1 to 20 wt% of a protective agent, wherein the weight percentages are based on the total weight of the moisture-sensitive composition.

In an embodiment, the graphene oxide content of the moisture-sensitive composition may be 0.01 wt%, 0.05 wt%, 0.15 wt%, 0.2 wt%, 0.38 wt%, 0.4 wt%, 0.45 wt%, 0.5 wt%, 0.7 wt%, 0.8 wt%, 0.9 wt%, 1 wt%, etc.; the amount of the protective agent may be 0.2 wt%, 0.5 wt%, 0.8 wt%, 1 wt%, 1.5 wt%, 1.8 wt%, 2 wt%, 5 wt%, 8 wt%, 10 wt%, 12 wt%, 15 wt%, 18 wt%, etc.

In one embodiment, the moisture-sensitive composition includes Graphene Oxide (GO), a protectant, a thickener, a surfactant, and a solvent.

In one embodiment, the moisture-sensitive composition comprises 0.01 to 1 wt% of graphene oxide, 0.1 to 20 wt% of a protective agent, 0.01 to 10 wt% of a thickening agent, 0.1 to 1 wt% of a surfactant, and the balance of a solvent.

In one embodiment, the thickener may be, but is not limited to, an associative polyurethane.

In one embodiment, the surfactant can be, but is not limited to, polyoxyethylene ether methacrylate, polyoxyethylene ether acrylate, polyoxypropylene ether acrylate, fatty acid polyglycol ester, polyol ester, fatty amine polyoxyethylene ether, and the like.

In one embodiment, the solvent may be a polar solvent such as, but not limited to, water, ethanol, acetone, butanone, ethyl acetate, ethylene glycol, n-propanol, and the like.

In one embodiment, the humidity-sensitive composition can be used as a humidity-sensitive material to form a humidity-sensitive layer (or humidity-sensitive medium layer) of a humidity sensor.

In one embodiment, the graphene oxide sheet layer is coated by adding a protective agent, so that a composite graphene oxide humidity-sensitive material can be formed, and the phenomenon that the humidity-sensitive property is lost due to the gradual reaction of active groups (hydroxyl groups, epoxy groups, carboxyl groups at the edges and the like) of the graphene oxide with substances in the ambient atmosphere is avoided. Meanwhile, the moisture-sensitive characteristic of the graphene oxide is not affected by the addition of the protective agent, the response to the environmental humidity can be realized, the good correspondence can be kept for a long time, and the problem of instability of the existing graphene oxide moisture-sensitive layer is solved.

As shown in fig. 1 and 2, a flexible humidity sensor according to an embodiment of the present invention includes a flexible substrate 1, a conductive layer 2, a humidity sensitive layer 4, a connection lead 5, and a film connector terminal 6; wherein, the conducting layer 2 is arranged on the flexible substrate 1, the humidity sensitive layer 4 is arranged on the conducting layer 2, the connecting lead 5 is used for connecting the conducting layer 2 and the film connector terminal 6, and the humidity sensitive layer 4 is prepared from the humidity sensitive composition.

In one embodiment, at least one channel 3 is formed in the conductive layer 2, and the number and shape of the channels 3 are determined by the structure of the conductive layer 2. In the present invention, the structure of the conductive layer 2 is not limited, and for example, it may be the structure shown in fig. 3, that is, the structure similar to an interdigital electrode, so that the channel 3 in the conductive layer 2 is composed of a plurality of connected U-shapes arranged in the same direction.

In one embodiment, the thickness of the humidity sensitive layer 4 may be 10 to 20000nm, such as 20nm, 50nm, 100nm, 500nm, 800nm, 1000nm, 1500nm, 5000nm, 10000nm, 20000nm, etc.

In one embodiment, the conductive layer 2 and the graphene oxide composite humidity-sensitive layer 4 are printed on the flexible substrate 1 in sequence by a full printing method.

In one embodiment, the material of the connecting leads 5 may be the same as the conductive layer 2, so that the connecting leads 5 and the conductive layer 2 may be printed at the same time. In the present invention, the conductive layer 2 and the moisture sensitive layer 4 are printed in a non-limited manner, and may be screen-printed, for example.

In one embodiment, the flexible substrate 1 may be a PET polyester film, and a PET polyester flexible film material is used as a substrate, so that the humidity sensor can be conveniently implanted into various products for detecting and monitoring the related humidity.

In one embodiment, the thickness of the conductive layer 2 can be 1-20 um, such as 5um, 8um, 10um, 15um, etc.

In the present invention, the structure of the film connector terminal 6 is not limited, and may be, for example, the structure shown in fig. 4.

In one embodiment, the connection lead 5 and the film connector terminal 6 may be connected by riveting using a manual riveting press or an electric riveting press.

In an embodiment, the flexible substrate 1, the conductive layer 2, and the graphene oxide composite humidity-sensitive layer 4 all have certain flexibility and can be bent and deformed, so that the whole sensor can be bent and deformed, and then the sensor can be applied to the field of wearable devices.

The humidity sensor provided by the embodiment of the invention has the advantages of simple structure, low cost, light weight, good flexibility and biocompatibility, good long-term stability, and easiness in miniaturization, integration and array realization of small-volume and multi-channel humidity detection.

The invention provides a preparation method of a flexible humidity sensor, which comprises the step of preparing the flexible humidity sensor in a full printing mode.

The preparation method of the flexible humidity sensor comprises the following steps:

the method comprises the following steps: cleaning the flexible substrate 1 before printing;

step two: printing a conductive layer 2 and a connecting lead 5 on the flexible substrate 1 by using conductive paste in a printing mode, and curing according to the curing condition of the conductive paste;

step three: printing the humidity-sensitive layer 4 on the conductive layer 2 by using graphene oxide slurry in a printing mode, wherein the humidity-sensitive layer can be dried naturally or in a drying oven, and the drying temperature can be not more than 50 ℃;

the printing in the second step and the printing in the third step can be performed in batch, fig. 5 is a schematic structural diagram of batch printing of the conductive layer and the connecting lead, and fig. 6 is a schematic structural diagram of batch printing of the humidity sensitive layer.

Step four: the humidity sensors printed in batch are cut into single sensors, and then are connected with peripheral circuits through the film connector terminals 6 to form a humidity sensing system.

Step five: calibrating the manufactured humidity sensor: and placing the graphene oxide humidity sensor in an environment box, connecting the graphene oxide humidity sensor with a source meter, and collecting I-V signals so as to obtain the corresponding relation between the I-V signals and the humidity value.

In one embodiment, the pre-press cleaning treatment of step one includes, but is not limited to, chemical treatment, photochemical treatment, plasma treatment, corona treatment, antistatic treatment, and the like.

In one embodiment, the conductive paste used in the second step may be a conductive silver paste.

In one embodiment, the graphene oxide slurry may be prepared by:

(1) mixing graphene oxide, a surfactant and deionized water (solvent) in a certain proportion at room temperature, and carrying out ultrasonic treatment for 10-60 min to obtain a required graphene oxide dispersion liquid;

(2) and sequentially adding the protective agent, the thickening agent and the residual solvent into the graphene oxide dispersion liquid, heating, stirring, dispersing and dissolving until graphene oxide slurry is formed, filtering and printing.

In one embodiment, the graphene oxide used for preparing the slurry may be a graphene oxide powder or a graphene oxide aqueous dispersion.

In one embodiment, if the graphene oxide aqueous dispersion is used in step (1), the concentration thereof may be 0.5 to 10mg/ml, for example, 1mg/ml, 2mg/ml, 2.5mg/ml, 3mg/ml, 5mg/ml, or 8 mg/ml.

In one embodiment, the ultrasonic treatment in step (1) has an operating frequency of 40kHz and an ultrasonic power of 420 w.

In one embodiment, the heating temperature in step (2) may be 40 to 100 ℃, for example, 50 ℃, 65 ℃, 75 ℃, 80 ℃ and the like; the stirring rate may be 400 to 1000r/min, such as 500r/min, 750r/min, 900r/min, etc.

In one embodiment, the relevant components and proportions of the graphene oxide slurry can be adjusted according to the printing mode and the final performance requirements of the device, so as to meet the requirements of the printing process and the application scenarios on the performance of the device.

In one embodiment, the cutting method in step four may be, but not limited to, laser cutting, guillotine cutting, die cutting, etc.

In one embodiment, the environmental chamber in step five may be, but is not limited to, a Webster C4-340Pro environmental chamber.

In one embodiment, the source table in step five may be, but is not limited to, a Jishili 2450 type source table. The source meter can be connected with a computer, and a mathematical fitting formula of the humidity sensor can be directly obtained through software analysis.

Compared with the defect that the humidity sensor based on the graphene oxide is unstable in the prior art, the preparation method provided by the embodiment of the invention combines the advantages of graphene oxide protection and adhesion increase, and realizes the stability of performance parameters of the humidity sensor based on the graphene oxide by adopting the simple sensor structure of the graphene oxide composite slurry.

The preparation method of the humidity sensor provided by the embodiment of the invention has the advantages of simple process steps, simple preparation process, few working procedures, low cost, uniform film formation of the graphene oxide composite humidity-sensitive layer, good stability, simple method and no pollution, and is manufactured in batches by using a full printing process.

Hereinafter, a humidity sensor and a method for manufacturing the same according to an embodiment of the present invention will be further described with reference to the accompanying drawings. The starting materials used are commercially available.

Example 1

The flexible substrate 1(PET polyester film) was subjected to plasma treatment.

The conductive layer 2 and the connecting leads 5 are printed on the flexible substrate 1 in batch by using conductive silver paste in a screen printing mode, the structure and the connection mode of the conductive layer 2 and the connecting leads 5 are shown in FIG. 2, and the result of batch printing is shown in FIG. 5; wherein, the thickness of conducting layer 2 is 10 um.

Mixing 90 parts by mass of 5mg/ml graphene oxide aqueous dispersion (GO is 0.45 part by mass) and 0.5 part by mass of polyoxyethylene ether methacrylate at room temperature, and carrying out ultrasonic treatment for 50-60 min (working frequency is 40kHz and ultrasonic power is 420w) to obtain the required graphene oxide dispersion; sequentially adding 1 part by mass of waterborne polyurethane, 0.5 part by mass of associated polyurethane and 8 parts by mass of deionized water into the graphene oxide dispersion liquid, heating, stirring, dispersing and dissolving, wherein the heating temperature is 40-45 ℃, and the stirring speed is 400r/min until graphene oxide slurry is formed. And filtering the graphene oxide slurry, printing the humidity-sensitive layers 4 on the conductive layer 2 in batches by adopting a screen printing mode (as shown in fig. 6), and naturally drying after printing to prepare a plurality of humidity sensors, wherein the thickness of the humidity-sensitive layers 4 is 15000 nm.

Cutting a plurality of humidity sensors printed in batches into single sensors through a paper cutter, connecting a connecting lead 5 with a film connector terminal 6 in a riveting mode through an electric riveting machine, and connecting the connecting lead with a peripheral circuit through the film connector terminal 6 to form a humidity sensing system; the structure of the film connector terminal 6 is shown in fig. 4.

Placing the graphene oxide humidity sensor in a Weisifuqi C4-340Pro environment test box, connecting the graphene oxide humidity sensor with a Gishili 2450 type source meter, and collecting I-V signals to obtain a corresponding relation between the I-V signals and humidity values; the source meter is connected with a computer, and a mathematical fitting formula of the humidity sensor is directly obtained through software analysis.

FIG. 7A is a humidity-sensitive characteristic test chart of the humidity sensor (GO + aqueous polyurethane) manufactured in example 1 and the humidity sensor (GO) manufactured in comparative example; fig. 7B is a stability test chart of the humidity sensor manufactured in example 1. As can be seen from fig. 7A and 7B, the protective agent of example 1 of the present application has a small influence on the moisture sensitivity of the humidity sensor, and the moisture sensitivity changes little within 3 months, so that high stability can be maintained.

Example 2

The raw materials and process conditions used in this example are substantially the same as those in example 1, except that: the used protective agent is water-based vinyl chloride-vinyl acetate copolymer, wherein the mass parts of 5mg/ml graphene oxide water dispersion are 75.8 (0.379 for GO), 0.5 for polyoxyethylene ether methacrylate, 18 for water-based vinyl chloride-vinyl acetate copolymer lipid, 0.7 for associated polyurethane and 5 for deionized water.

FIG. 8A is a graph showing humidity-sensitive characteristics of the humidity sensor (GO + aqueous chlorine vinegar) manufactured in example 2 and the humidity sensor (GO) manufactured in comparative example; fig. 8B is a stability test chart of the humidity sensor manufactured in example 2. As can be seen from fig. 8A and 8B, the protective agent of example 2 of the present application has a small influence on the moisture sensitivity of the humidity sensor, and the moisture sensitivity changes little within 3 months, so that high stability can be maintained.

Example 3

The raw materials and process conditions used in this example are substantially the same as those in example 1, except that: the used protective agent is water-based saturated polyester resin, wherein the mass part of 5mg/ml graphene oxide water dispersion is 76(GO is 0.38), the mass part of polyoxyethylene ether methacrylate is 0.5, the mass part of water-based saturated polyester resin is 12, the mass part of associated polyurethane is 0.5, and the mass part of deionized water is 11.

FIG. 9A is a graph showing the humidity-sensitive characteristics of the humidity sensor (GO + aqueous saturated polyester) manufactured in example 3 and the humidity sensor (GO) manufactured in comparative example; fig. 9B is a stability test chart of the humidity sensor manufactured in example 3. As can be seen from fig. 9A and 9B, the protective agent of example 3 of the present application has a small influence on the moisture sensitivity of the humidity sensor, and the moisture sensitivity changes little within 3 months, so that high stability can be maintained.

Example 4

The raw materials and process conditions used in this example are substantially the same as those in example 1, except that: the used protective agent is alkyd resin, wherein the mass parts of 5mg/ml graphene oxide water dispersion are 79.2 (0.396) and 0.5 of polyoxyethylene ether methacrylate, 5.0 of alkyd resin, 0.3 of associated polyurethane and 15 of deionized water.

FIG. 10A is a graph showing the humidity-sensitive characteristics of the humidity sensor (GO + alkyd) manufactured in example 4 and the humidity sensor (GO) manufactured in comparative example; fig. 10B is a stability test chart of the humidity sensor manufactured in example 4. As can be seen from fig. 10A and 10B, the protective agent of example 4 of the present application has a small influence on the moisture sensitivity of the humidity sensor, and the moisture sensitivity changes little within 3 months, so that high stability can be maintained.

Example 5

The raw materials and process conditions used in this example are substantially the same as those in example 1, except that: the dosage of the protective agent is polyamide resin, wherein the mass part of the graphene oxide aqueous dispersion of 5mg/ml is 80.1(GO is 0.4), the mass part of the polyoxyethylene ether methacrylate is 0.5, the mass part of the polyamide resin is 1.8, the mass part of the associated polyurethane is 0.6, and the mass part of the ethanol is 17.

FIG. 11A is a graph showing the humidity-sensitive characteristics of the humidity sensor (GO + polyamide) produced in example 5 and the humidity sensor (GO) produced in comparative example; FIG. 11B is a stability test chart of the humidity sensor manufactured in example 5. As can be seen from fig. 11A and 11B, the protective agent of example 5 of the present application has a small influence on the moisture sensitivity of the humidity sensor, and the moisture sensitivity changes little within 3 months, so that high stability can be maintained.

Comparative example

The raw materials and process conditions used in this comparative example were substantially the same as those in example 1, except that: no protectant ingredients were added.

Fig. 12 is a graph comparing the initial measurement value and the measurement value after 3 months of the humidity sensor manufactured by the comparative example. As can be seen from fig. 12, the humidity sensor of the comparative example to which no protectant component was added varied greatly within 3 months, and was less stable.

Unless otherwise defined, all terms used herein have the meanings commonly understood by those skilled in the art.

The described embodiments of the present invention are for illustrative purposes only and are not intended to limit the scope of the present invention, and those skilled in the art may make various other substitutions, alterations, and modifications within the scope of the present invention, and thus, the present invention is not limited to the above-described embodiments but only by the claims.