A hexagonal boron nitride nanosheet-based humidity sensor and a preparation method thereof

Abstract

The application provides a hexagonal boron nitride nanosheet-based humidity sensor and a preparation method thereof. The hexagonal boron nitride nanosheet-based humidity sensor comprises, from bottom to top, a substrate layer, a tine electrode and a hexagonal boron nitride nanosheet layer. The hexagonal boron nitride nanosheet layer is composed of hexagonal boron nitride nanosheets with a diameter of 100-200 nm. The hexagonal boron nitride nanosheet-based humidity sensor has a response (resistance change) to humidity as high as 28384% under the condition of a relative humidity of 85%, and the response and recovery times are 3 s and 5.5 s, respectively. The hexagonal boron nitride nanosheet-based humidity sensor can maintain excellent stability in a relative humidity range of 11%-85%, and the preparation method of the hexagonal boron nitride nanosheet is simple.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of humidity sensors, in particular to a hexagonal boron nitride nanosheet-based humidity sensor and a preparation method thereof. BACKGROUND

[0002] Since the 18th century, people have been researching humidity monitoring. Today, in people's daily life, from large-scale atmospheric humidity monitoring to grain storage environment humidity monitoring, and small-scale human respiratory monitoring, humidity sensors are widely used. In general, humidity refers to the water vapor content in the surrounding environment, which is an important non-biological factor affecting human life. Absolute humidity, relative humidity and other definitions are used to describe humidity. Among them, the term relative humidity is often used to describe the water vapor content in the surrounding atmosphere considering temperature and pressure, which is a commonly used humidity description unit.

[0003] In recent years, people have been more and more deeply involved in the research of humidity sensors, and the application scenarios suitable for humidity sensors are being developed. More and more materials have shown potential in humidity sensors, such as metal oxides, polymers, semiconductors, and other materials. However, low sensitivity, low biocompatibility, and toxicity are common problems of most of these materials, which limit their application in human-related fields. SUMMARY

[0004] The present application aims to overcome the shortcomings of the above-mentioned humidity sensors, and designs a humidity sensor with excellent performance using hexagonal boron nitride nanosheets. The humidity sensor has a response (resistance change) to humidity as high as 28384% under the condition of a relative humidity of 85%, and can maintain excellent stability in the relative humidity range of 11%-85%. Moreover, the preparation method of hexagonal boron nitride nanosheets is simple.

[0005] The technical solution of the present application is as follows: a hexagonal boron nitride nanosheet-based humidity sensor, comprising a substrate layer, a fork electrode and a hexagonal boron nitride nanosheet layer arranged in order from bottom to top.

[0006] Further, the hexagonal boron nitride nanosheet layer is composed of hexagonal boron nitride nanosheets with a diameter of 100-200 nm.

[0007] Further, the fork electrode is a gold fork electrode.

[0008] Further, the substrate layer is a polyethylene terephthalate substrate.

[0009] A preparation method of a hexagonal boron nitride nanosheet-based humidity sensor, comprising the following steps:

[0010] S1 uses magnetron sputtering technology and photoetching technology to carve out the interdigital shape on the gold layer of the substrate layer, and obtains the interdigital electrode;

[0011] S2 drops the hexagonal boron nitride nanosheet dispersion liquid on the interdigital electrode to obtain a hexagonal boron nitride nanosheet-based humidity sensor.

[0012] Further, in step S1, the preparation method of the hexagonal boron nitride nanosheet dispersion liquid is as follows: the hexagonal boron nitride nanosheet powder is dispersed in deionized water, and ultrasonic treatment is performed for 20-30 minutes to obtain a uniformly dispersed hexagonal boron nitride nanosheet dispersion liquid.

[0013] Further, in step S1, the interdigital electrode is a gold electrode, and the method of magnetron sputtering technology is as follows: the cleaned polyethylene terephthalate substrate is transferred to a magnetron sputtering vacuum chamber, and gold is sputtered after vacuumizing, and the sputtering time is 3-5 min.

[0014] Further, in step S1, the interdigital electrode is a gold electrode, and a layer of gold is sputtered on the substrate layer by using magnetron sputtering technology, and the specific method of photoetching technology is as follows:

[0015] 1) First, uniformly coat the polyethylene terephthalate substrate after sputtering gold with photoresist, and the spin coating conditions of the photoresist are 15-25 s at 600 r / s, and then 45-55 s at 5000 r / s;

[0016] 2) Pre-baking: heat the substrate layer with spin-coated photoresist at 110-120 DEG C for 60-100 s;

[0017] 3) Photoetching: use an ultraviolet photoetching machine and a prepared mask to perform exposure treatment, and the exposure time is 90 s;

[0018] 4) Post-baking: heat the substrate layer after exposure treatment at 110-120 DEG C for 60-100 s;

[0019] 5) Development: develop in a developing solution for 30-60 s after exposure, remove the residual developing solution after the pattern appears, and blow dry;

[0020] 6) Gold removal: place the developed substrate layer in a gold removal solution for 5-10 s to remove excess gold, and finally blow dry to obtain the interdigital electrode pattern.

[0021] 7) Gel removal: clean the substrate layer after gold removal to remove the surface photoresist, and finally blow dry to obtain the interdigital electrode.

[0022] The beneficial effects of the present application are as follows:

[0023] The hexagonal boron nitride nanosheet-based humidity sensor of this invention exhibits excellent performance, including high sensitivity, a wide detection range, and good stability. The hexagonal boron nitride nanosheets possess a large specific surface area and are richly coated with hydrophilic functional groups. The adsorption of water molecules by these numerous hydrophilic functional groups contributes to the high response characteristics. Furthermore, the fabrication method of the hexagonal boron nitride nanosheet-based humidity sensor of this invention is simple. Attached Figure Description

[0024] 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 introduced below. The drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a schematic diagram of the structural principle of a hexagonal boron nitride nanosheet-based humidity sensor;

[0026] Figure 2 This is a transmission electron micrograph of hexagonal boron nitride nanosheets;

[0027] Figure 3 This involves testing the current-voltage characteristics of a humidity sensor under different humidity levels.

[0028] Figure 4 This is a test of the switching stability of a hexagonal boron nitride nanosheet-based humidity sensor;

[0029] Figure 5 This is a long-term stability test of the hexagonal boron nitride nanosheet-based humidity sensor;

[0030] Figure 6 It is the response time of the hexagonal boron nitride nanosheet-based humidity sensor;

[0031] Figure 7 The image shows the infrared spectrum of hexagonal boron nitride nanosheets. Detailed Implementation Plan

[0032] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] like Figure 1As shown, a hexagonal boron nitride nanosheet-based humidity sensor includes a substrate layer, a tine electrode and a hexagonal boron nitride nanosheet layer arranged in order from bottom to top. The tine electrode is a gold tine electrode, and the substrate layer is a polyethylene terephthalate substrate.

[0034] A preparation method of a hexagonal boron nitride nanosheet humidity sensor, characterized in that it comprises the following steps:

[0035] S1, using a magnetron sputtering technique to sputter a layer of gold on a polyethylene terephthalate substrate, the specific method being as follows:

[0036] Cut the polyethylene terephthalate substrate into appropriate size (1.5x1.5cm), and ultrasonically clean the cut polyethylene terephthalate substrate in alcohol and deionized water for 10 minutes in order.

[0037] Transfer the cleaned polyethylene terephthalate substrate to a magnetron sputtering vacuum chamber, sputter gold after vacuumizing, and the sputtering time is 3-5 minutes.

[0038] S2, using a photolithography technique to etch a tine shape on the gold layer of the polyethylene terephthalate substrate to obtain a tine electrode;

[0039] 1) First, uniformly coat the polyethylene terephthalate substrate with sputtered gold with photoresist, and the spin coating conditions are 20s, 600r / s first, and then 40s, 5000r / s;

[0040] 2) Pre-baking: heat the polyethylene terephthalate substrate with spin-coated photoresist at 110°C for 90s;

[0041] 3) Photolithography: use a UV photolithography machine and a prepared mask to perform exposure treatment, and the exposure time is 90s;

[0042] 4) Post-baking: heat the polyethylene terephthalate substrate after exposure treatment at 110°C for 90s;

[0043] 5) Development: develop in a developing solution for 30s after exposure, rinse with deionized water after the pattern appears, remove the residual developing solution, and finally dry with nitrogen;

[0044] 6) Gold removal: place the developed polyethylene terephthalate substrate in a gold removal solution for 5s to remove excess gold, and finally dry with nitrogen to obtain a clear tine electrode pattern.

[0045] 7) Photoresist removal: clean the polyethylene terephthalate substrate after gold removal in acetone, alcohol and deionized water for 30s to remove the surface photoresist, and finally dry with nitrogen to complete the preparation of the tine electrode.

[0046] S3 drops the hexagonal boron nitride nanosheet dispersion on the prong electrode to obtain a hexagonal boron nitride nanosheet-based humidity sensor.

[0047] The preparation method of the hexagonal boron nitride nanosheet dispersion is as follows: 0.5 mg of hexagonal boron nitride nanosheet powder is dispersed in 4 ml of deionized water, and after 20-30 minutes of ultrasonic treatment, a uniformly dispersed hexagonal boron nitride nanosheet dispersion is obtained. As shown in Figure 2 The transmission electron micrograph of the hexagonal boron nitride nanosheet is shown.

[0048] The prepared hexagonal boron nitride nanosheet-based humidity sensor is tested under different humidity conditions (the instrument used is a semiconductor analyzer, 4200S), and the test results are shown in Figure 3 From the figure, it can be seen that the current of the hexagonal boron nitride nanosheet-based humidity sensor increases with the increase of relative humidity, that is, the device can calibrate humidity with current value, achieving the purpose of humidity sensing.

[0049] The working principle of the hexagonal boron nitride nanosheet-based humidity sensor is as follows:

[0050] The humidity sensing characteristics of the sensor depend on the adsorption and desorption of water molecules on the surface of the hexagonal boron nitride nanosheet. The hexagonal boron nitride nanosheet has a hydrophilic surface, as shown in Figure 3 With the increase of the relative humidity of the environment in which the humidity sensor is located, the water molecules that can be adsorbed on the surface increase, resulting in a change in the conductivity of the hexagonal boron nitride nanosheet. The detailed mechanism is as follows: when the hexagonal boron nitride nanosheet is in a low humidity environment, a small amount of water molecules are adsorbed by the surface hydrophilic functional groups, but ion migration is difficult, so it exhibits low current under low humidity conditions. With the increase of humidity, more water molecules are adsorbed on the surface of the hexagonal boron nitride nanosheet, forming a continuous water network, and the ion migration freedom in the network increases, and the current of the device also gradually increases.

[0051] According to the formula Figure 3 and the formula The response of the humidity sensor to humidity at X% relative humidity is calculated, where I0 and I X are the sensor currents at 11% RH (I0 = 6.13 x 10 -12 A) and X% RH, respectively. At 85% RH, the response of the humidity sensor to humidity can reach about 28384%.

[0052] The hexagonal boron nitride nanosheet-based humidity sensor needs to be tested for its stability, including the switching stability and long-term stability of the device. These two performances determine the reliability of the hexagonal boron nitride nanosheet-based humidity sensor.

[0053] The switching stability test results of the hexagonal boron nitride nanosheet-based humidity sensor are as follows:

[0054] Switch stability is the repeatability of the device in common language, we selected three different humidity environments (43%, 75%, 85%) to test the switch stability of the hexagonal boron nitride nanosheet-based humidity sensor, and the test results are as shown in Figure 4 When the humidity increases, the current of the device will immediately increase, and when the humidity returns to the initial humidity, the current of the device will also immediately return to the original level. The results show that the device has repeatable adsorption and desorption behavior, small fluctuation, good repeatability and reliability.

[0055] The long-term stability test results of the hexagonal boron nitride nanosheet-based humidity sensor are as follows:

[0056] Figure 5 is the test result of the hexagonal boron nitride nanosheet-based humidity sensor after being placed for 30 days. It can be seen that the current value of the sensor at different humidity levels remains almost unchanged in one month, which proves that our sensor has good stability and durability.

[0057] Figure 6 is the response time analysis of the hexagonal boron nitride nanosheet-based humidity sensor under 85% relative humidity, from which it can be seen that the response and recovery times are 3s and 5.5s respectively, the response time is shorter, which proves that the sensor has relatively fast response.

[0058] Figure 7 is the infrared spectrum image analysis of hexagonal boron nitride nanosheet, from which it can be seen that the surface of hexagonal boron nitride nanosheet has more hydrophilic functional groups (-OH, -NH2), which is the main reason for the good performance of the humidity sensor.

[0059] The above only describes the preferred embodiments of the present application, and is not used to limit the present application, any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A hexagonal boron nitride nanoplate-based humidity sensor, characterized by: The humidity sensor comprises, from bottom to top, a substrate layer, a tine electrode and a hexagonal boron nitride nanosheet layer, and the hexagonal boron nitride nanosheet-based humidity sensor is calibrated with humidity in terms of current value. The hexagonal boron nitride nanosheet layer is composed of hexagonal boron nitride nanosheets with a diameter of 100-200 nm. The preparation method of the hexagonal boron nitride nanosheet humidity sensor comprises the following steps: S1. Preparing the tine electrode on the substrate layer by using a magnetron sputtering technology and a photolithography technology; S2. Dropping the hexagonal boron nitride nanosheet dispersion liquid on the tine electrode to obtain the hexagonal boron nitride nanosheet-based humidity sensor.

2. The hexagonal boron nitride nanoplate-based humidity sensor according to claim 1, wherein: The tine electrode is a gold electrode.

3. The hexagonal boron nitride nanoplatelets-based humidity sensor according to claim 1, wherein: The substrate layer is a polyethylene terephthalate substrate.

4. The hexagonal boron nitride nanoplatelet-based humidity sensor according to claim 1, wherein In step S2, the preparation method of the hexagonal boron nitride nanosheet dispersion liquid is as follows: dispersing 0.4-0.6 mg of hexagonal boron nitride nanosheet powder in 4 ml of deionized water, and then performing ultrasonic treatment for 20-30 minutes to obtain the uniformly dispersed hexagonal boron nitride nanosheet dispersion liquid.

5. The hexagonal boron nitride nanoplatelets-based humidity sensor according to claim 1, wherein, In step S1, the tine electrode is a gold electrode, and the method of the magnetron sputtering technology is as follows: transferring the cleaned substrate layer into a magnetron sputtering vacuum chamber, sputtering gold after vacuumizing, and sputtering for 3-5 minutes.

6. The hexagonal boron nitride nanoplatelets-based humidity sensor according to claim 1 or 5, wherein, In step S1, the tine electrode is a gold electrode, and a layer of gold is sputtered on the substrate layer by using the magnetron sputtering technology. The specific method of the photolithography technology is as follows: 1) First, uniformly coat photoresist on the substrate layer after sputtering gold, and the conditions for spin-coating photoresist are as follows: 15-25 s at 600 r / s, and then 45-55 s at 5000 r / s; 2) Pre-baking: heating the substrate layer with spin-coated photoresist at 110-120°C for 60-100 s; 3) Photolithography: performing exposure treatment by using an ultraviolet photolithography machine and a prepared mask, and the exposure time is 60-100 s; 4) Post-baking: heating the substrate layer after exposure treatment at 110-120°C for 60-100 s; 5) Development: developing in a developing solution for 30-60 s after exposure, removing the residual developing solution after the pattern appears, and then blowing dry; 6) Gold removal: placing the developed substrate layer in a gold removal solution for 5-10 s to remove the excess gold, and then blowing dry to obtain the tine electrode pattern; 7) Photoresist removal: cleaning the substrate layer after gold removal to remove the surface photoresist, and then blowing dry to obtain the tine electrode.

Images