阅读说明：本技术 柔性电容式温度传感器及其制作方法 (Flexible capacitive temperature sensor and manufacturing method thereof ) 是由 衣芳 陈泽桐 于 2020-04-08 设计创作，主要内容包括：本发明公开了柔性电容式温度传感器及其制作方法,该柔性电容式温度传感器为顺排六方氮化硼/PVDF薄膜层、MXene/PVA薄膜层、六方氮化硼/PVDF薄膜层的三明治结构,三明治结构的上下外表面分别镀有金电极,以形成柔性电容式温度传感器的上、下电极；其中间层的MXene/PVA薄膜,高导电性的MXene和高绝缘性的聚合物基体之间存在界面极化,能够提供较高的介电常数并且介电常数随温度变化出现较大变化；而上下两层为六方氮化硼/PVDF薄膜,六方氮化硼可以抑制电极上的电荷输入到介质中,而且夹层结构使得层与层之间出现屏障效应,增强电荷捕获,使其获得高的击穿强度,在高电场条件下保护器件。(The invention discloses a flexible capacitive temperature sensor and a manufacturing method thereof, wherein the flexible capacitive temperature sensor is a sandwich structure of an in-line hexagonal boron nitride/PVDF film layer, an MXene/PVA film layer and a hexagonal boron nitride/PVDF film layer, and the upper outer surface and the lower outer surface of the sandwich structure are respectively plated with a gold electrode to form an upper electrode and a lower electrode of the flexible capacitive temperature sensor; interface polarization exists between the MXene/PVA film of the middle layer, the MXene with high conductivity and the polymer matrix with high insulation, so that higher dielectric constant can be provided and the dielectric constant is greatly changed along with the temperature change; the upper layer and the lower layer are hexagonal boron nitride/PVDF films, the hexagonal boron nitride can inhibit charges on the electrodes from being input into the medium, and the interlayer structure enables a barrier effect to occur between the layers, enhances charge capture, enables the charge capture to obtain high breakdown strength and protects the device under the condition of a high electric field.)

1. The flexible capacitive temperature sensor is characterized in that the flexible capacitive temperature sensor is of a sandwich structure of a hexagonal boron nitride/PVDF thin film layer, an MXene/PVA thin film layer and a hexagonal boron nitride/PVDF thin film layer which are arranged in sequence, and the upper outer surface and the lower outer surface of the sandwich structure are respectively plated with gold electrodes to form the upper electrode and the lower electrode of the flexible capacitive temperature sensor.

2. The flexible capacitive temperature sensor of claim 1, wherein the hexagonal boron nitride/PVDF thin film layer has a hexagonal boron nitride content of 8.0 wt%.

3. The flexible capacitive temperature sensor according to claim 1, wherein the MXene content in the MXene/PVA film layer is 2.5 wt%.

4. The manufacturing method of the flexible capacitive temperature sensor is characterized by comprising the following steps:

s1, taking a glass slide, sequentially putting the glass slide into absolute ethyl alcohol and DI water for ultrasonic cleaning, and then putting the glass slide into a blast drying oven for drying and keeping the constant temperature at 70 ℃;

s2, coating the pre-configured hexagonal boron nitride/PVDF mixed solution on the glass slide obtained in the step S1, and drying at 70 ℃ in a drying box to obtain a hexagonal boron nitride/PVDF film with the hexagonal boron nitride content of 8.0 wt%;

s3, annealing the dried and cured hexagonal boron nitride/PVDF film;

s4, carrying out ultrasonic treatment on the pre-configured MXene/PVA mixed suspension to fully mix the suspension;

s5, coating the MXene/PVA mixed suspension on the hexagonal boron nitride/PVDF film obtained in the step S3, and drying at 40 ℃ to obtain an MXene/PVA film with the MXene content of 2.5 wt%;

s6, repeating the steps S2 and S3, coating the obtained hexagonal boron nitride/PVDF film on the structure formed in the step S5, and preparing sandwich structures of the ordered hexagonal boron nitride/PVDF film layer, the MXene/PVA film layer and the hexagonal boron nitride/PVDF film layer;

and S7, plating gold electrodes on the upper and lower outer surfaces of the sandwich structure by using a sputtering coating technology.

5. The method for manufacturing a flexible capacitive temperature sensor according to claim 4, wherein the step S1 specifically comprises: and (3) putting a glass slide into absolute ethyl alcohol and DI water successively, respectively, carrying out ultrasonic cleaning for 20min, and then putting the glass slide into a forced air drying oven to dry and keep the constant temperature at 70 ℃.

6. The method of claim 4, wherein the pre-configuring of the hexagonal boron nitride/PVDF mixed solution comprises: weighing 2.5g of PVDF powder, and completely dissolving the PVDF powder in a DMF solvent at 60 ℃ by magnetic stirring to obtain a PVDF solution; weighing 0.2g of hexagonal boron nitride nanosheet, and dissolving the hexagonal boron nitride nanosheet in a DMF solution through ultrasonic treatment to obtain a hexagonal boron nitride suspension; and mixing the PVDF solution and the hexagonal boron nitride suspension, and stirring by magnetic force at room temperature until the mixed solution is free from bubbles.

7. The method for manufacturing a flexible capacitive temperature sensor according to claim 4, wherein the step S3 specifically comprises: and placing the dried and cured hexagonal boron nitride/PVDF film in a decompression furnace to anneal for 6 hours at 180 ℃.

8. The method of claim 4, wherein the pre-configuring step of the MXene/PVA mixed suspension comprises: weighing 0.1g of MXene powder, and dissolving in DI water to obtain MXene solution; 4g of PVA solution was added to the MXene solution to mix, and the mixed solution was subjected to ultrasonic treatment.

Technical Field

The invention relates to the technical field of preparation of nano materials and nano functional devices, in particular to a flexible capacitive temperature sensor and a manufacturing method thereof.

Background

The sensor is a detection device which can sense measured information and convert the sensed information into an electric signal or other information in a required form to be output so as to meet the requirements of information transmission, processing, storage, display, recording, control and the like, in other words, the sensor is like a sensing organ such as human five sense organs and the like. The sensor has the characteristics of miniaturization, digitalization, intellectualization, multifunction, systematization and networking. The method is the first link for realizing automatic detection and automatic control. The existence and development of the sensor enable the object to have the senses of touch, taste, smell and the like, and the object slowly becomes alive. At present, sensors are widely applied to various fields of social development and human life, such as industrial automation, aerospace technology, military engineering, robotics, ocean exploration, environmental monitoring, security, medical diagnosis and the like.

With the advent of integrated circuits in recent years, capacitive sensors have been developed to overcome their inherent shortcomings, and have become a very versatile and potentially viable sensor. The capacitive sensor can be classified into a polar distance variation type, an area variation type and a medium variation type. The polar distance changing type is generally used to measure a minute linear displacement or a polar distance change due to an external force, pressure, vibration, or the like, such as a capacitive pressure sensor. The area change type is generally used to measure angular displacement or large linear displacement. The medium change type is commonly used for level measurement and determination of temperature, density and humidity of various media. The capacitive sensor has been receiving more and more attention from the scientific research community because of its characteristics such as high impedance, low power, simple structure, strong adaptability.

With the development and application requirements of wearable devices, the development of flexible devices is receiving more and more attention. Polymer dielectrics have been increasingly valued in the field of flexible devices because of their ultra-high intrinsic breakdown strength and their flexibility. However, the dielectric constant of the polymer is low, and the energy density of the discharge does not reach an ideal level, so that the development of the polymer is limited. It has been reported that in order to obtain a higher dielectric constant, conductive fillers such as carbon nanotubes and MXene are added to polymers such as PVDF and PVA to obtain a capacitor with better performance. Experiments show that after the conductive filler is added, although a high dielectric constant can be obtained, the breakdown strength of the capacitor is greatly reduced, and the capacitor cannot normally work under high electric field intensity.

Disclosure of Invention

The invention provides a flexible capacitive temperature sensor and a manufacturing method thereof, aiming at solving the problem that the existing flexible capacitive sensor cannot have higher dielectric constant, lower dielectric loss and higher breakdown strength.

In order to achieve the above purpose, the technical means adopted is as follows:

the flexible capacitive temperature sensor is of a sandwich structure of an in-line hexagonal boron nitride/PVDF (polyvinylidene fluoride) film layer, an MXene/PVA (polyvinyl acetate) film layer and a hexagonal boron nitride/PVDF film layer, and the upper outer surface and the lower outer surface of the sandwich structure are respectively plated with a gold electrode to form an upper electrode and a lower electrode of the flexible capacitive temperature sensor.

In the above scheme, the sandwich structure of the flexible capacitive temperature sensor: the middle layer is an MXene/PVA film, and interface polarization exists between the MXene with high conductivity and the polymer matrix with high insulativity, so that a high dielectric constant can be provided and is greatly changed along with the temperature change; the upper layer and the lower layer are hexagonal boron nitride/PVDF films, the hexagonal boron nitride can inhibit charges on the electrodes from being input into the medium, and the interlayer structure enables barrier effect to occur between the layers, so that the layers can obtain high breakdown strength and protect the device under the condition of high electric field. Therefore, the flexible capacitive temperature sensor has good flexibility, can detect the temperature change in a certain temperature range, and has higher dielectric constant, lower dielectric loss and higher breakdown strength.

Preferably, in the hexagonal boron nitride/PVDF thin film layer, the hexagonal boron nitride content is 8.0 wt%. In the preferred scheme, the content of 8.0 wt% of hexagonal boron nitride can improve the breakdown strength of the capacitor and obtain a high dielectric coefficient, so that the flexible capacitive temperature sensor has better performance.

Preferably, the MXene content in the MXene/PVA film layer is 2.5 wt%. In the preferred embodiment, the dielectric constant of the capacitor is ideal and the dielectric loss is lowest under the MXene content of 2.5 wt%, so that the flexible capacitive temperature sensor has better performance.

The invention also provides a manufacturing method of the flexible capacitive temperature sensor, which comprises the following steps:

s1, taking a glass slide, sequentially putting the glass slide into absolute ethyl alcohol and DI water for ultrasonic cleaning, and then putting the glass slide into a blast drying oven for drying and keeping the constant temperature at 70 ℃;

s2, coating the pre-configured hexagonal boron nitride/PVDF mixed solution on the glass slide obtained in the step S1, and drying at 70 ℃ in a drying box to obtain a hexagonal boron nitride/PVDF film with the hexagonal boron nitride content of 8.0 wt%;

s3, annealing the dried and cured hexagonal boron nitride/PVDF film;

s4, carrying out ultrasonic treatment on the pre-configured MXene/PVA mixed suspension to fully mix the suspension;

s5, coating the MXene/PVA mixed suspension on the hexagonal boron nitride/PVDF film obtained in the step S3, and drying at 40 ℃ to obtain an MXene/PVA film with the MXene content of 2.5 wt%;

s6, repeating the steps S2 and S3, coating the obtained hexagonal boron nitride/PVDF film on the structure formed in the step S5, and preparing sandwich structures of the ordered hexagonal boron nitride/PVDF film layer, the MXene/PVA film layer and the hexagonal boron nitride/PVDF film layer;

and S7, plating gold electrodes on the upper and lower outer surfaces of the sandwich structure by using a sputtering coating technology.

In the scheme, the flexible capacitive temperature sensor prepared by the method has the advantages that firstly, an MXene/PVA film is arranged in the middle, interfacial polarization exists between the MXene with high conductivity and the polymer matrix with high insulation, high dielectric constant can be provided, and the dielectric constant is greatly changed along with temperature change; the upper layer and the lower layer are hexagonal boron nitride/PVDF films, the hexagonal boron nitride can inhibit charges on the electrodes from being input into the medium, and the interlayer structure enables barrier effect to occur between the layers, so that the layers can obtain high breakdown strength and protect the device under the condition of high electric field. Therefore, the flexible capacitive temperature sensor has good flexibility, can detect the temperature change in a certain temperature range, and has higher dielectric constant, lower dielectric loss and higher breakdown strength.

Preferably, the step S1 specifically includes: and (3) putting a glass slide into absolute ethyl alcohol and DI water successively, respectively, carrying out ultrasonic cleaning for 20min, and then putting the glass slide into a forced air drying oven to dry and keep the constant temperature at 70 ℃. In the preferred scheme, the carrier plate is preheated and insulated to 70 ℃, and the mixed solution is coated subsequently, so that the conditions that the shrinkage is uneven and the device is bent due to overlarge temperature difference of the upper surface and the lower surface of the device in the device drying process can be avoided.

Preferably, the pre-configuring step of the hexagonal boron nitride/PVDF mixed solution comprises: weighing 2.5g of PVDF powder, and completely dissolving the PVDF powder in a DMF solvent at 60 ℃ by magnetic stirring to obtain a PVDF solution; weighing 0.2g of hexagonal boron nitride nanosheet, and dissolving the hexagonal boron nitride nanosheet in a DMF solution through ultrasonic treatment to obtain a hexagonal boron nitride suspension; and mixing the PVDF solution and the hexagonal boron nitride suspension, and stirring by magnetic force at room temperature until the mixed solution is free from bubbles.

Preferably, the step S3 specifically includes: and placing the dried and cured hexagonal boron nitride/PVDF film in a decompression furnace to anneal for 6 hours at 180 ℃. In the preferred scheme, the annealing treatment can eliminate residual stress, stabilize the size of the film, reduce the deformation and crack tendency, and homogenize the structure and components of the material to improve the material performance.

Preferably, the pre-configuring step of the MXene/PVA mixed suspension comprises: weighing 0.1g of MXene powder, and dissolving in DI water to obtain MXene solution; 4g of PVA solution was added to the MXene solution to mix, and the mixed solution was subjected to ultrasonic treatment.

Compared with the prior art, the technical scheme of the invention has the beneficial effects that:

according to the flexible capacitive temperature sensor and the manufacturing method thereof, firstly, an MXene/PVA film is arranged in the middle of the flexible capacitive temperature sensor, interface polarization exists between the MXene with high conductivity and a polymer matrix with high insulativity, a high dielectric constant can be provided, and the dielectric constant is greatly changed along with the temperature change; the upper layer and the lower layer are hexagonal boron nitride/PVDF films, the hexagonal boron nitride can inhibit charges on the electrodes from being input into the medium, and the interlayer structure enables barrier effect to occur between the layers, so that the layers can obtain high breakdown strength and protect the device under the condition of high electric field. Therefore, the flexible capacitive temperature sensor has good flexibility, can detect the temperature change in a certain temperature range, and has higher dielectric constant, lower dielectric loss and higher breakdown strength.

Drawings

Fig. 1 is a schematic three-dimensional structure diagram of the capacitive temperature sensor according to embodiment 1.

Fig. 2 is a flowchart of a method for manufacturing the capacitive temperature sensor according to embodiment 2.

Fig. 3 is a process diagram of the capacitive sensor of example 2.

FIG. 4 shows the change of dielectric constant with temperature of the mixed solutions of PVA and MXene/PVA in example 2.

Detailed Description

The drawings are for illustrative purposes only and are not to be construed as limiting the patent;

for the purpose of better illustrating the embodiments, certain features of the drawings may be omitted, enlarged or reduced, and do not represent the size of an actual product;

it will be understood by those skilled in the art that certain well-known structures in the drawings and descriptions thereof may be omitted.

The technical solution of the present invention is further described below with reference to the accompanying drawings and examples.