Nickel oxide-based wide-temperature-range high-precision temperature sensor and preparation method thereof
1. A preparation method of a wide-temperature-range high-precision temperature sensor based on nickel oxide is characterized by comprising the following steps:
(1) preparing slurry:
respectively weighing nickel oxide powder, a film forming agent, a surfactant and a solvent, and performing ultrasonic dispersion to obtain nickel oxide slurry;
(2) preparing a temperature sensitive layer:
taking a substrate, pretreating, uniformly coating the nickel oxide slurry on the substrate, and heating and curing to obtain a temperature sensitive layer;
(3) preparation of interdigital electrode
Preparing an electrode on the temperature sensitive layer in the step (2);
(4) PDMS encapsulation
And (4) spin-coating PDMS on the electrode obtained in the step (3), and curing to obtain the temperature sensor.
2. The preparation method according to claim 1, wherein the film forming agent is one or more of polyimide solution, ethyl cellulose and polymethyl methacrylate.
3. The preparation method according to claim 1, wherein the surfactant is one or a combination of cetyl trimethyl ammonium bromide and sodium dodecyl sulfate.
4. The method according to claim 1, wherein in the step (1), the solvent is one or a combination of two of N, N-dimethylformamide and N, N-dimethylacetamide.
5. The production method according to claim 1, wherein in the step (1), the mass ratio of the nickel oxide to the film-forming agent is 0.1 to 0.9: 1; the mass ratio of the nickel oxide to the surfactant is 1:0 to 0.1; the mass ratio of the nickel oxide to the solvent is 1: 0.5-5.
6. The production method according to claim 1, wherein in the step (2), the substrate is a rigid substrate or a flexible substrate;
the rigid substrate comprises one or more of aluminum nitride, silicon oxide and glass; the flexible substrate is one or the combination of PI and PET.
7. The method according to claim 6, further comprising a step of peeling off the substrate before the PDMS encapsulation in the step (4); the specific operation of the stripping is as follows:
and (4) soaking the device with the electrode prepared in the step (3) in deionized water until the device is desorbed from the substrate.
8. The preparation method according to claim 1, wherein in the step (2), the heating is performed for curing as follows: the curing is completed after the materials are heated for 1h at the temperature of 60-90 ℃ and then heated for 1h at the temperature of 120-180 ℃.
9. The preparation method according to claim 1, wherein in the step (3), the electrode is prepared by any one of metal evaporation, blade coating or magnetron sputtering;
the electrode material is any one of silver, titanium, copper, gold and platinum;
the thickness of the electrode is 10nm-10 um.
10. A wide temperature range high precision temperature sensor prepared by the preparation method of any one of claims 1 to 9.
Background
The temperature is a physical quantity for representing the cold and hot degree of an object and plays a very important role in life. With the rapid development of the internet of things and intelligent equipment, the temperature sensor becomes more and more indispensable. Nickel oxide has been studied for temperature sensors because of its excellent negative temperature resistance characteristics. However, the nickel oxide slurry composition reported at present has great limitations on the film forming property, the application range and the temperature test interval. The prior art (ACS appl. mater. interfaces 2013, 5, 12954) discloses that a water-based slurry is prepared by using diethylene glycol, deionized water and nickel oxide, and a temperature sensor is obtained by using an aerosol jet printing mode, and the thermal sensitivity constant is 4300K. The slurry has the problems of poor film forming property, mechanical property and adhesion. The prior literature (adv.mater.2020, 32, 1905527) discloses that isoamyl alcohol, hexadecyl trimethyl ammonium bromide, polyvinylpyrrolidone and nickel oxide are used for obtaining slurry through ultrasonic dispersion, and the slurry is spread on a flexible substrate and dried at normal temperature to obtain a temperature sensor, so that the film forming property of the system is greatly improved, but the mechanical property and the adhesion are poor; meanwhile, the melting point of the polyvinylpyrrolidone is 130 ℃, the temperature measuring interval of the temperature sensor prepared by the method is limited to 25-75 ℃, and the temperature sensor cannot work due to the fact that the polyvinylpyrrolidone is melted at high temperature.
Disclosure of Invention
In order to solve the problems in the prior art, the invention provides a wide-temperature-range high-precision temperature sensor and a preparation method thereof. The temperature sensor disclosed by the invention realizes a wide temperature range of 150K-470K, and simultaneously has the temperature difference measurement precision of 0.05K and a thermal constant exceeding 5000K. The temperature sensor has better flexibility, mechanical strength and stability.
The technical scheme adopted by the invention is as follows:
a preparation method of a wide-temperature-range high-precision temperature sensor based on nickel oxide comprises the following steps:
(1) preparing slurry:
respectively weighing nickel oxide powder, a film forming agent, a surfactant and a solvent, and performing ultrasonic dispersion to obtain nickel oxide slurry;
(2) preparing a temperature sensitive layer:
taking a substrate, pretreating, uniformly coating the nickel oxide slurry on the substrate, and heating and curing to obtain a temperature sensitive layer;
(3) preparation of interdigital electrode
Preparing an electrode on the temperature sensitive layer in the step (2);
(4) PDMS encapsulation
And (4) spin-coating PDMS on the electrode obtained in the step (3), and curing to obtain the temperature sensor.
The film forming agent is one or a combination of polyimide solution, ethyl cellulose and polymethyl methacrylate.
The surfactant is one or the combination of two of cetyl trimethyl ammonium bromide and lauryl sodium sulfate.
The solvent is one or the combination of two of N, N-dimethylformamide and N, N-dimethylacetamide.
The mass ratio of the nickel oxide to the film forming agent is 0.1-0.9: 1; the mass ratio of the nickel oxide to the surfactant is 1: 0-0.1; the mass ratio of the nickel oxide to the solvent is 1: 0.5-5.
In the step (2), the substrate is a rigid substrate or a flexible substrate;
the rigid substrate comprises one or more of aluminum nitride, silicon oxide and glass; the flexible substrate is one or the combination of PI and PET. The combination is obtained by selecting a rough substrate or grinding the rough substrate and preparing the nickel oxide slurry on the rough substrate, so that the flexibility and the mechanical property of the temperature sensor are improved.
When the substrate is a smooth substrate, before the PDMS encapsulation in step (4), a step of peeling off is further included to peel off the substrate; the specific operation of the stripping is as follows:
and (4) soaking the device with the electrode prepared in the step (3) in deionized water until the device is desorbed from the substrate. Therefore, the self-supporting flexible temperature sensor is prepared by selecting a smooth substrate such as glass and the like to prepare the temperature sensor and soaking the temperature sensor in water to realize stripping.
In the step (2), the heating and curing are as follows: the curing is completed after the materials are heated for 1h at the temperature of 60-90 ℃ and then heated for 1h at the temperature of 120-180 ℃.
In the step (3), the method for preparing the electrode adopts any one of metal evaporation, blade coating or magnetron sputtering;
the electrode material is any one of silver, titanium, copper, gold and platinum;
the thickness of the electrode is 10nm-10 um.
The wide-temperature-range high-precision temperature sensor prepared by the method.
The invention has the beneficial effects that:
according to the wide-temperature-range high-precision temperature sensor, nickel oxide powder, a film forming agent such as a polyimide solution, a surfactant and a solvent are mixed properly to prepare nickel oxide slurry, the nickel oxide slurry is coated on a substrate to prepare a temperature sensitive layer, then an electrode is prepared on the temperature sensitive layer, and PDMS is packaged to prepare the temperature sensor; moreover, the nickel oxide has a good negative temperature resistance effect, so that the temperature sensor is ensured to have high-precision temperature measurement performance; the temperature sensor can realize a wide temperature range of 150K-470K, and simultaneously has the temperature difference measurement precision of 0.05K and the thermal sensitive constant exceeding 5000K. The temperature sensor has better flexibility, mechanical strength and stability.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
FIG. 1 is a schematic structural diagram of a self-supporting temperature sensor (unencapsulated PDMS) according to example 1 of the present invention;
FIG. 2 is a schematic structural diagram of a temperature sensor (unencapsulated PDMS) obtained in example 2 of the present invention;
FIG. 3 is a schematic structural view of a temperature sensor obtained in example 2 of the present invention;
FIG. 4 is a resistance change curve of the temperature sensor obtained in example 1 of the present invention at a temperature difference of 0.05 degrees Celsius;
FIG. 5 is a resistance change curve of the temperature sensor obtained in example 1 of the present invention at 300K to 470K;
FIG. 6 is a resistance change curve of the temperature sensor obtained in example 1 of the present invention in a range of 150K to 300K;
FIG. 7 is a resistance change curve of the temperature sensor obtained in example 4 of the present invention at 300K to 430K;
FIG. 8 is a graph showing the resistance change of the temperature sensor obtained in example 4 of the present invention at 300K-430K.
In the figure, 1-PDMS, 2-electrode, 3-temperature sensitive layer and 4-substrate.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be described in detail below. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be derived by a person skilled in the art from the examples given herein without any inventive step, are within the scope of the present invention.
Example 1
The embodiment provides a preparation method of a self-supporting temperature sensor, which comprises the following steps:
(1) preparing slurry:
weighing nickel oxide powder, a polyimide solution and hexadecyl trimethyl ammonium bromide according to the mass ratio of 0.5:1:0.05, adding a solvent N, N-dimethylformamide (the mass ratio of nickel oxide to the solvent is 1: 2.5), mixing, and performing ultrasonic dispersion in a centrifugal tube until nickel oxide is uniformly dispersed to obtain nickel oxide slurry;
(2) preparing a temperature sensitive layer:
taking glass as a substrate, carrying out plasma cleaning on the substrate, uniformly coating the nickel oxide slurry on the pretreated substrate, heating at 80 ℃ for 1h, heating at 120 ℃ for 1h, and curing to obtain a temperature sensitive layer;
(3) preparation of interdigital electrode
Preparing an electrode on the temperature sensitive layer in the step (2) by adopting a metal evaporation method, and specifically operating as follows: covering a stainless steel metal interdigital electrode mask on the temperature sensitive layer, and evaporating a titanium electrode, namely preparing an electrode with the thickness of 10nm on the temperature sensitive layer;
(4) PDMS encapsulation
Soaking the device with the electrode prepared in the step (3) in deionized water until the device is desorbed from the substrate (the structure is shown in figure 1); and then, spin-coating PDMS on the electrode of the device, and curing in an oven to obtain the self-supporting temperature sensor.
As shown in fig. 4, which is a resistance variation curve of the temperature sensor of this embodiment at a temperature difference of 0.05 degrees celsius, it can be seen from the graph that a slight variation of temperature can be detected by a variation of the resistance of the sensor. In the figure, 50% NiO means the mass fraction of nickel oxide compared with PI.
Fig. 5 shows the resistance variation curve of the temperature sensor in this embodiment from 300K to 470K, and it can be seen from the graph that: the resistance is continuously reduced along with the temperature rise in the range, a good negative temperature resistance effect is shown, and the detection of temperature change is realized.
Fig. 6 shows the resistance variation curve of the temperature sensor in this embodiment from 150K to 300K, and it can be seen from the graph that: at low temperatures, the sensor also achieves a sensitive response and measurement to temperature.
Example 2
The embodiment provides a preparation method of a sensor with a substrate temperature, which comprises the following steps:
(1) preparing slurry:
weighing nickel oxide powder, a polyimide solution and hexadecyl trimethyl ammonium bromide according to the mass ratio of 0.1:1:0.05, adding a solvent N, N-dimethylformamide (the mass ratio of nickel oxide to the solvent is 1: 5), mixing, and performing ultrasonic dispersion in a centrifugal tube until nickel oxide is uniformly dispersed to obtain nickel oxide slurry;
(2) preparing a temperature sensitive layer:
taking aluminum nitride as a substrate, carrying out plasma cleaning on the substrate, uniformly coating the nickel oxide slurry on the pretreated substrate, heating at 80 ℃ for 1h, heating at 120 ℃ for 1h, and curing to obtain a temperature sensitive layer;
(3) preparation of interdigital electrode
Preparing an electrode on the temperature sensitive layer in the step (2) by adopting a metal evaporation method, and specifically operating as follows: covering a stainless steel metal interdigital electrode mask on the temperature sensitive layer, and evaporating a titanium electrode, namely preparing an electrode with the thickness of 10nm on the temperature sensitive layer;
(4) PDMS encapsulation
And (3) spin-coating PDMS on the electrode obtained in the step (3), curing in an oven to obtain the temperature sensor, wherein the structures of the temperature sensor before and after the PDMS is packaged are respectively shown in fig. 2 and fig. 3.
Example 3
The embodiment provides a preparation method of a sensor with a substrate temperature, which comprises the following steps:
(1) preparing slurry:
weighing nickel oxide powder and a polyimide solution according to a mass ratio of 0.3:1, adding a solvent N, N-dimethylacetamide (the mass ratio of nickel oxide to the solvent is 1: 0.5), mixing, and performing ultrasonic dispersion in a centrifugal tube until nickel oxide is uniformly dispersed to obtain nickel oxide slurry;
(2) preparing a temperature sensitive layer:
taking silicon oxide as a substrate, carrying out plasma cleaning on the substrate, uniformly coating the nickel oxide slurry on the pretreated substrate, heating at 80 ℃ for 1h, heating at 120 ℃ for 1h, and curing to obtain a temperature sensitive layer;
(3) preparation of interdigital electrode
Preparing an electrode on the temperature sensitive layer in the step (2) by adopting a metal evaporation method, and specifically operating as follows: covering a stainless steel metal interdigital electrode mask on the temperature sensitive layer, and evaporating a copper electrode, namely preparing an electrode with the thickness of 20nm on the temperature sensitive layer;
(4) PDMS encapsulation
And (4) spin-coating PDMS on the electrode obtained in the step (3), and curing in an oven to obtain the temperature sensor.
Example 4
The embodiment provides a preparation method of a sensor with a substrate temperature, which comprises the following steps:
(1) preparing slurry:
weighing nickel oxide powder, a polyimide solution and hexadecyl trimethyl ammonium bromide according to a mass ratio of 0.4:1:0.05, adding a solvent N, N-dimethylformamide (the mass ratio of nickel oxide to the solvent is 1: 3), mixing, and performing ultrasonic dispersion in a centrifugal tube until nickel oxide is uniformly dispersed to obtain nickel oxide slurry;
(2) preparing a temperature sensitive layer:
taking PI as a substrate, polishing the substrate by using sand paper, uniformly coating the nickel oxide slurry on the pretreated substrate, heating at 80 ℃ for 1h, heating at 120 ℃ for 1h, and curing to obtain a temperature sensitive layer;
(3) preparation of interdigital electrode
Preparing an electrode on the temperature sensitive layer in the step (2) by adopting a metal evaporation method, and specifically operating as follows: covering a stainless steel metal interdigital electrode mask on the temperature sensitive layer, and evaporating a gold electrode, namely preparing an electrode with the thickness of 15nm on the temperature sensitive layer;
(4) PDMS encapsulation
And (4) spin-coating PDMS on the electrode obtained in the step (3), and curing in an oven to obtain the temperature sensor.
Fig. 7 shows the resistance variation curve of the temperature sensor obtained in this embodiment in the range of 300K to 470K, and it can be seen from the graph that: the resistance is continuously reduced along with the temperature rise in the range, a good negative temperature resistance effect is shown, and the detection of temperature change is realized.
Example 5
The embodiment provides a preparation method of a sensor with a substrate temperature, which comprises the following steps:
(1) preparing slurry:
weighing nickel oxide powder, a polyimide solution and hexadecyl trimethyl ammonium bromide according to the mass ratio of 0.3:1:0.01, adding a solvent N, N-dimethylformamide (the mass ratio of nickel oxide to the solvent is 1: 1.5), mixing, and performing ultrasonic dispersion in a centrifugal tube until nickel oxide is uniformly dispersed to obtain nickel oxide slurry;
(2) preparing a temperature sensitive layer:
taking PET as a substrate, cleaning the substrate by oxygen plasma, uniformly coating the nickel oxide slurry on the pretreated substrate, heating at 80 ℃ for 1h, heating at 120 ℃ for 1h, and curing to obtain a temperature sensitive layer;
(3) preparation of interdigital electrode
Preparing an electrode on the temperature sensitive layer in the step (2) by adopting a silver paste blade coating method, and specifically operating the following steps: sticking a PET interdigital electrode mask plate on the temperature sensitive layer, then coating silver paste on the PET interdigital electrode mask plate in a scraping manner, drying the silver paste, and removing PET, namely preparing an electrode with the thickness of 15nm on the temperature sensitive layer;
(4) PDMS encapsulation
And (4) spin-coating PDMS on the electrode obtained in the step (3), and curing in an oven to obtain the temperature sensor.
Fig. 8 shows the resistance variation curve of the temperature sensor obtained in this embodiment in the range of 300K to 470K, and it can be seen from the graph that: the resistance is continuously reduced along with the temperature rise in the range, a good negative temperature resistance effect is shown, and the detection of temperature change is realized.
Example 6
The embodiment provides a preparation method of a sensor with a substrate temperature, which comprises the following steps:
(1) preparing slurry:
weighing nickel oxide powder, a polyimide solution and hexadecyl trimethyl ammonium bromide according to the mass ratio of 0.9:1:0.1, adding a solvent N, N-dimethylformamide (the mass ratio of nickel oxide to the solvent is 1: 3), mixing, and performing ultrasonic dispersion in a centrifugal tube until nickel oxide is uniformly dispersed to obtain nickel oxide slurry;
(2) preparing a temperature sensitive layer:
taking silicon oxide as a substrate, carrying out plasma cleaning on the substrate, uniformly coating the nickel oxide slurry on the pretreated substrate, heating at 80 ℃ for 1h, heating at 120 ℃ for 1h, and curing to obtain a temperature sensitive layer;
(3) preparation of interdigital electrode
Preparing an electrode on the temperature sensitive layer in the step (2) by adopting a metal evaporation method, and specifically operating as follows: covering a stainless steel metal interdigital electrode mask on the temperature sensitive layer, and evaporating a copper electrode, namely preparing an electrode with the thickness of 12nm on the temperature sensitive layer;
(4) PDMS encapsulation
And (4) spin-coating PDMS on the electrode obtained in the step (3), and curing in an oven to obtain the temperature sensor.
Example 7
The embodiment provides a preparation method of a sensor with a substrate temperature, which comprises the following steps:
(1) preparing slurry:
weighing nickel oxide powder, a polyimide solution and hexadecyl trimethyl ammonium bromide according to the mass ratio of 0.9:1:0.1, adding a solvent N, N-dimethylformamide (the mass ratio of nickel oxide to the solvent is 1: 2.5), mixing, and performing ultrasonic dispersion in a centrifugal tube until nickel oxide is uniformly dispersed to obtain nickel oxide slurry;
(2) preparing a temperature sensitive layer:
taking silicon oxide as a substrate, carrying out plasma cleaning on the substrate, uniformly coating the nickel oxide slurry on the pretreated substrate, heating at 60 ℃ for 1h, heating at 120 ℃ for 1h, and curing to obtain a temperature sensitive layer;
(3) preparation of interdigital electrode
Preparing an electrode on the temperature sensitive layer in the step (2) by adopting a metal evaporation method, and specifically operating as follows: covering a stainless steel metal interdigital electrode mask on the temperature sensitive layer, and evaporating a copper electrode, namely preparing an electrode with the thickness of 12nm on the temperature sensitive layer;
(4) PDMS encapsulation
And (4) spin-coating PDMS on the electrode obtained in the step (3), and curing in an oven to obtain the temperature sensor.
Example 8
The embodiment provides a preparation method of a sensor with a substrate temperature, which comprises the following steps:
(1) preparing slurry:
weighing nickel oxide powder, an ethyl cellulose solution and sodium dodecyl sulfate according to a mass ratio of 0.9:1:0.1, adding a solvent N, N-dimethylformamide (the mass ratio of nickel oxide to the solvent is 1: 2), mixing, and performing ultrasonic dispersion in a centrifugal tube until nickel oxide is uniformly dispersed to obtain nickel oxide slurry;
(2) preparing a temperature sensitive layer:
taking silicon oxide as a substrate, carrying out plasma cleaning on the substrate, uniformly coating the nickel oxide slurry on the pretreated substrate, heating at 90 ℃ for 1h, then heating at 180 ℃ for 1h, and after curing is completed, preparing a temperature sensitive layer;
(3) preparation of interdigital electrode
Preparing an electrode on the temperature sensitive layer in the step (2) by adopting a metal evaporation method, and specifically operating as follows: covering a stainless steel metal interdigital electrode mask on the temperature sensitive layer, and evaporating a copper electrode, namely preparing an electrode with the thickness of 12nm on the temperature sensitive layer;
(4) PDMS encapsulation
And (4) spin-coating PDMS on the electrode obtained in the step (3), and curing in an oven to obtain the temperature sensor.
Example 9
The embodiment provides a preparation method of a sensor with a substrate temperature, which comprises the following steps:
(1) preparing slurry:
weighing nickel oxide powder, a polyethylene methyl acrylate solution and hexadecyl trimethyl ammonium bromide according to the mass ratio of 0.9:1:0.1, adding a solvent N, N-dimethylformamide (the mass volume ratio of the polyimide solution to the solvent is 1 g: 2ml), mixing, and performing ultrasonic dispersion in a centrifugal tube until nickel oxide is uniformly dispersed to obtain nickel oxide slurry;
(2) preparing a temperature sensitive layer:
taking silicon oxide as a substrate, carrying out plasma cleaning on the substrate, uniformly coating the nickel oxide slurry on the pretreated substrate, heating at 80 ℃ for 1h, heating at 130 ℃ for 1h, and curing to obtain a temperature sensitive layer;
(3) preparation of interdigital electrode
Preparing an electrode on the temperature sensitive layer in the step (2) by adopting a metal evaporation method, and specifically operating as follows: covering a stainless steel metal interdigital electrode mask on the temperature sensitive layer, and evaporating a copper electrode, namely preparing an electrode with the thickness of 12nm on the temperature sensitive layer;
(4) PDMS encapsulation
And (4) spin-coating PDMS on the electrode obtained in the step (3), and curing in an oven to obtain the temperature sensor.
Examples of the experiments
The temperature sensors obtained in examples 1, 3 and 4 were subjected to resistance and thermal constant detection, the obtained samples were placed in a closed probe station, temperature control was performed by a temperature control element in the probe station, the change in resistance value of the samples was measured by a two-probe method (applying voltage to measure current), and corresponding thermal constant values were calculated. The results are shown in table 1, wherein 30% nickel oxide, 40% nickel oxide, 50% nickel oxide refer to the mass fraction of nickel oxide in the film forming agent being 30% (example 3), 40% (example 4) and 50% (example 1), respectively.
Wherein the thermal sensitivity constant is calculated according to the following formula.
Wherein, T1、T2For absolute temperature, generally T1Has a value of 298.15K (25 ℃), T2The value of (D) was 323.15K (50 ℃).
TABLE 1
Sample (I)
298K resistance (omega)
323K resistance (omega)
Thermal constant (K)
30% nickel oxide
1.41*1012
5.56*1011
3579
40% nickel oxide
4.25*108
1.15*108
5027
50% Nickel oxide
3.36*108
8.77*107
5166
As can be seen from Table 1, the thermal constant of the temperature sensor obtained by the invention is as high as 5000K or more.
The above description is only for the specific embodiments of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present invention, and all the changes or substitutions should be covered within the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the appended claims.
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