Humidity Sensor and Preparation Method

Abstract

The present invention provides a humidity sensor and a preparation method thereof. The humidity sensor includes a signal processing unit located at the bottom, a sensing unit disposed on the signal processing unit, a gate disposed on the sensing unit, an insulating layer disposed on the gate, a graphene quantum dot layer disposed on the insulating layer, and a drain and a source disposed on the graphene quantum dot layer. Among them, the components of the graphene quantum dot layer include graphene quantum dots and zinc nitrate mixed according to a preset ratio. By using the present invention, problems such as slow response speed, inaccurate response, and easy overshoot in controlling humidity of existing humidity sensors can be solved.

Description

Technical Field

[0001] The present invention relates to the technical field of electroacoustic conversion, and more specifically, to a humidity sensor and a preparation method thereof. Background Art

[0002] Now, with the improvement of living standards, people's requirements for the quality of life are getting higher and higher, and the demand for humidity sensors is also increasing. Humidity sensors are used for real-time monitoring of indoor humidity. Among them, in many scientific research environments and warehouses, it is necessary to monitor the humidity through humidity sensors. In the calibration test and calibration of the humidity sensor production process, the sensor is required to have a very fast response speed to quickly respond to the real-time change of humidity.

[0003] At present, most humidity sensors on the market use polyimide as the humidity-sensitive material. When the humidity changes, the change in the capacitance value of the material is converted into a change in the electrical signal. However, the response speed of this material is too slow, generally requiring a response time of 5 - 10 s. The experience in consumer electronics applications is very poor, and the efficiency in industrial detection is very low. Therefore, it is urgent to solve this shortcoming of the humidity sensor and improve the use experience. Summary of the Invention

[0004] In view of the above problems, the purpose of the present invention is to provide a humidity sensor and a preparation method thereof to solve the problems of slow response speed, inaccurate response, and easy overshoot in controlling humidity of existing humidity sensors.

[0005] The present invention provides a humidity sensor, including a signal processing unit located at the bottom, an induction unit disposed on the signal processing unit, a gate disposed on the induction unit, an insulating layer disposed on the gate, a graphene quantum dot layer disposed on the insulating layer, and a drain and a source disposed on the graphene quantum dot layer. Among them,

[0006] The component of the graphene quantum dot layer includes graphene quantum dots and zinc nitrate mixed in a preset ratio.

[0007] In addition, preferably, the mass ratio of graphene quantum dots to zinc nitrate is 7 - 13:11 - 21.

[0008] In addition, preferably, the signal processing unit is a silicon substrate;

[0009] The insulating layer is a silicon dioxide layer.

[0010] In addition, preferably, the induction unit is a single crystal silicon, and the gate is a heavily doped P-type single crystal silicon. Among them, the induction unit is electrically connected to the signal processing unit through a wire.

[0011] In addition, preferably, the drain and the source are arranged at intervals, among which,

[0012] The materials of the drain and the source are aluminum, gold or copper;

[0013] The drain and the source are respectively electrically connected to the signal processing unit through wires.

[0014] The present invention also provides a preparation method of a humidity sensor, including:

[0015] Fix the sensing unit with an insulating layer on its surface on the signal processing unit;

[0016] Perform plasma treatment on the insulating layer;

[0017] After filtering the pre-prepared graphene quantum dot solution, place it on the plasma-treated insulating layer. Among them, dissolve graphene quantum dots and zinc nitrate in deionized water according to a preset ratio to form a graphene quantum dot solution;

[0018] Perform film-forming treatment on the filtered graphene quantum dot solution through a spin coater to form a graphene quantum dot layer on the insulating layer;

[0019] Form the drain and the source on the graphene quantum dot layer by evaporation coating;

[0020] Electrically connect the drain, the source, and the sensing unit to the signal processing unit through wires.

[0021] In addition, a preferred solution is that the plasma treatment on the insulating layer includes:

[0022] Clean the insulating layer;

[0023] Perform surface activation treatment on the cleaned insulating layer through plasma. Among them, the surface activation treatment time is 5 - 15 min, and the power is 20 - 100 w.

[0024] In addition, a preferred solution is that the dissolution of graphene quantum dots and zinc nitrate in deionized water according to a preset ratio to form a graphene quantum dot solution includes:

[0025] First, dissolve graphene quantum dots in deionized water according to a mass ratio of 1:7 - 13;

[0026] Then, add zinc nitrate. Among them, the mass ratio of zinc nitrate to the deionized water is 1:11 - 21;

[0027] Finally, heat the mixed liquid of graphene quantum dots and zinc nitrate at a temperature of 130 - 280 °C for 30 - 80 min to form a graphene quantum dot solution.

[0028] In addition, a preferred solution is that the filtered graphene quantum dot solvent is formed into a film by a spin coater to form a graphene quantum dot layer on the insulating layer, including:

[0029] Absorb the pre-prepared graphene quantum dot solution through a syringe. A filter is provided at the needle position of the syringe to filter impurities in the graphene quantum dot solution;

[0030] Drop the graphene quantum dot solution after filtering impurities onto the insulating layer;

[0031] The graphene quantum dot solution is uniformly coated on the insulating layer by a spin coater. The rotation speed of the spin coater is 2000 - 5000 rpm, and the rotation time is 30 - 90 s;

[0032] Bake the graphene quantum dot liquid coated on the insulating layer to evaporate the liquid and form a graphene quantum dot layer. The baking temperature is 60 - 100 °C, and the baking time is 10 - 30 min.

[0033] In addition, a preferred solution is that the induction unit with an insulating layer on its surface is fixed on the signal processing unit by silicone bonding. The thickness of the glue is 10 - 50 μm, the curing condition is 110 - 180 °C, and the time is 15 - 60 min; The insulating layer is provided on the induction unit by deposition or thermal oxidation.

[0034] From the above technical solutions, it can be seen that the humidity sensor and its preparation method provided by the present invention use graphene quantum dots and zinc nitrate as the main materials as the humidity-sensitive materials of the humidity sensor. Through the principle of field effect transistors, under the action of the porous characteristics of graphene, the response speed can reach the millisecond level, thus solving the problems of slow response speed, inaccurate response, and easy overshoot of humidity control in existing humidity sensors.

[0035] To achieve the above and related purposes, one or more aspects of the present invention include the features that will be described in detail later. The following description and the accompanying drawings illustrate certain exemplary aspects of the present invention in detail. However, these aspects only indicate some of the various ways in which the principles of the present invention can be used. In addition, the present invention aims to include all these aspects and their equivalents. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] By referring to the following description in conjunction with the accompanying drawings and the content of the claims, and with a more comprehensive understanding of the present invention, other objects and results of the present invention will become more apparent and easier to understand. In the drawings:

[0037] Figure 1 It is a schematic cross-sectional view of a humidity sensor according to an embodiment of the present invention;

[0038] Figure 2 Schematic top view of a humidity sensor according to an embodiment of the present invention;

[0039] Figure 3 Schematic flow chart of a method for preparing a humidity sensor according to an embodiment of the present invention.

[0040] The reference numerals therein include: 1, signal processing unit; 2, sensing unit; 3, insulating layer; 4, drain; 5, graphene quantum dot layer; 6, source; 7, wire; 8, gate.

[0041] In all the drawings, the same reference numerals indicate similar or corresponding features or functions. Detailed implementation manners

[0042] In the following description, for the purpose of illustration, in order to provide a comprehensive understanding of one or more embodiments, many specific details are set forth. However, it is obvious that these embodiments can also be implemented without these specific details. In other instances, well-known structures and devices are shown in block diagram form for the convenience of describing one or more embodiments.

[0043] In the description of the present invention, it should be understood that the orientation or positional relationships indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. are based on the orientation or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0044] In view of the problems of slow response speed, inaccurate response, and easy overshoot in controlling humidity of the existing humidity sensors mentioned above, the present invention provides a humidity sensor and a preparation method thereof.

[0045] The following will describe in detail the specific embodiments of the present invention with reference to the accompanying drawings.

[0046] To illustrate the structure of the humidity sensor provided by the present invention, Figure 1 - Figure 2 The humidity sensor is exemplarily marked from different angles. Specifically, Figure 1 shows a cross-section of the humidity sensor according to an embodiment of the present invention; Figure 2 shows a top view of the humidity sensor according to an embodiment of the present invention.

[0047] As Figure 1 and Figure 2As shown together, the present invention provides a humidity sensor, including a signal processing unit 1 located at the bottom, a sensing unit 2 provided on the signal processing unit 1, a gate 8 provided on the sensing unit 2, an insulating layer 3 provided on the gate 8, a graphene quantum dot layer 5 provided on the insulating layer 3, and a drain 4 and a source 6 provided on the graphene quantum dot layer 5. Among them, the components of the graphene quantum dot layer 5 include graphene quantum dots and zinc nitrate, and the mass ratio of graphene quantum dots to zinc nitrate is 7-13:11-21.

[0048] In an embodiment of the present invention, the signal processing unit 1 is a silicon substrate. The signal processing unit is used for signal transmission. The interior of the signal processing unit includes a humidity signal processing unit, a calibration unit, and a temperature sensor. Since the signal processing unit made of silicon material is fabricated by conventional technical means, no detailed description will be given here.

[0049] Among them, a sensing unit 2 of the humidity sensor is provided on the signal processing unit 1. The material of the sensing unit 2 is heavily doped P-type silicon. The signal processing unit 1 and the sensing unit 2 are fixed together by bonding.

[0050] Among them, the sensing unit 2 is single crystal silicon, and the gate 8 is heavily doped P-type single crystal silicon. An insulating layer 3 is provided on the sensing unit 2. The insulating layer 3 is a silicon dioxide layer. Among them, the insulating layer 3 can be formed by deposition or by thermal oxidation of the sensing unit 2. In specific applications, a suitable method is selected according to actual needs.

[0051] Among them, the sensing unit 2 is electrically connected to the signal processing unit 1 through a wire. The drain 4 and the source 6 are arranged at intervals. Among them, the drain 4 and the source 6 are aluminum, gold or copper; the drain 4 and the source 6 are respectively electrically connected to the signal processing unit 1 through a wire 7.

[0052] Corresponding to the above structure, the present invention also provides a preparation method of a humidity sensor. Figure 3 The flowchart of the preparation method of the humidity sensor according to the embodiment of the present invention is shown.

[0053] As Figure 3 shown, the preparation method of the humidity sensor provided by the present invention includes:

[0054] S310: Fix the sensing unit with an insulating layer on its surface on the signal processing unit;

[0055] S320: Perform plasma treatment on the insulating layer;

[0056] S330: After filtering the pre-prepared graphene quantum dot solution, place it on the plasma-treated insulating layer. Among them, dissolve graphene quantum dots and zinc nitrate in deionized water according to a preset ratio to form a graphene quantum dot solution;

[0057] S340: Perform film-forming treatment on the filtered graphene quantum dot solution through a spin coater to form a graphene quantum dot layer on the insulating layer;

[0058] S350: Form a drain electrode and a source electrode on the graphene quantum dot layer by evaporation;

[0059] S360: Electrically connect the drain electrode, the source electrode, and the sensing unit to the signal processing unit through wires respectively.

[0060] In step S310, fix the sensing unit with an insulating layer on its surface to the signal processing unit by bonding; and set the insulating layer on the sensing unit by deposition or thermal oxidation.

[0061] In step S320, the plasma treatment of the insulating layer includes:

[0062] S321: Clean the insulating layer;

[0063] S322: Perform surface activation treatment on the cleaned insulating layer through plasma. Among them, the surface activation treatment time is 5 - 15 min, and the power is 20 - 100 w.

[0064] In step S330, the step of dissolving graphene quantum dots and zinc nitrate in deionized water according to a preset ratio to form a graphene quantum dot solution includes:

[0065] First, dissolve graphene quantum dots in deionized water according to a mass ratio of 1:7 - 13;

[0066] Then, add zinc nitrate. Among them, the mass ratio of zinc nitrate to the deionized water is 1:11 - 21;

[0067] Finally, heat the mixed liquid of graphene quantum dots and zinc nitrate at a temperature of 130 - 280 °C for 30 - 80 min to form a graphene quantum dot solution.

[0068] In step S340, the step of performing film-forming treatment on the filtered graphene quantum dot solution through a spin coater to form a graphene quantum dot layer on the insulating layer includes:

[0069] S341: Aspirate the pre-prepared graphene quantum dot solution through a syringe. Among them, set a filter at the needle tip position of the syringe to filter impurities in the graphene quantum dot solution;

[0070] S342: Drop the graphene quantum dot solution after filtering impurities onto the insulating layer;

[0071] S343: Uniformly coat the graphene quantum dot solution on the insulating layer by a spin coater, wherein the rotation speed of the spin coater is 2000 - 5000 rpm and the rotation time is 30 - 90 s;

[0072] S344: Bake the graphene quantum dot liquid coated on the insulating layer to evaporate the liquid and form a graphene quantum dot layer, wherein the baking temperature is 60 - 100 °C and the baking time is 10 - 30 min.

[0073] For the embodiments of the preparation method of the humidity sensor provided by the present invention, since they are basically similar to the embodiments of the humidity sensor, for the relevant parts, refer to the partial description of the device embodiments, and details are not described herein again.

[0074] It can be seen from the above embodiments that for the humidity sensor and the preparation method provided by the present invention, graphene quantum dots and zinc nitrate are used as the main materials as the humidity-sensitive materials of the humidity sensor. According to the field effect transistor principle, under the action of the porous characteristics of graphene, the response speed can reach the millisecond level, thus solving the problems of slow response speed, inaccurate response, and easy overshoot in controlling humidity of the existing humidity sensors.

[0075] As described above, the humidity sensor and the preparation method proposed according to the present invention are described by way of example with reference to the accompanying drawings. However, those skilled in the art should understand that various improvements can be made to the above-mentioned humidity sensor and the preparation method of the present invention without departing from the content of the present invention. Therefore, the protection scope of the present invention should be determined by the content of the appended claims.

Claims

1. A humidity sensor, characterized in that, It includes a signal processing unit located at the bottom, a sensing unit disposed on the signal processing unit, a gate disposed on the sensing unit, an insulating layer disposed on the gate, a graphene quantum dot layer disposed on the insulating layer, and a drain and a source disposed on the graphene quantum dot layer. Among them, the components of the graphene quantum dot layer include graphene quantum dots and zinc nitrate mixed in a preset ratio; among them, the mass ratio of the graphene quantum dots to the zinc nitrate is 7-13:11-21.

2. The humidity sensor according to claim 1, wherein the signal processing unit is a silicon substrate; the insulating layer is a silicon dioxide layer.

3. The humidity sensor according to claim 1, wherein the sensing unit is a single crystal silicon, and the gate is a heavily doped P-type single crystal silicon. Among them, the sensing unit is electrically connected to the signal processing unit through a wire.

4. The humidity sensor according to claim 1, wherein the drain and the source are spaced apart. Among them, the materials of the drain and the source are aluminum, gold or copper; the drain and the source are respectively electrically connected to the signal processing unit through wires.

5. A method for preparing a humidity sensor, the preparation method comprising: fixing a sensing unit with an insulating layer on its surface on a signal processing unit; performing plasma treatment on the insulating layer; after filtering the pre-prepared graphene quantum dot solution, placing it on the insulating layer after plasma treatment. Among them, graphene quantum dots and zinc nitrate are dissolved in deionized water in a preset ratio to form a graphene quantum dot solution; performing film-forming treatment on the filtered graphene quantum dot solution through a spin coater to form a graphene quantum dot layer on the insulating layer; forming a drain and a source on the graphene quantum dot layer by evaporation; electrically connecting the drain, the source, and the sensing unit to the signal processing unit through wires respectively; the step of dissolving graphene quantum dots and zinc nitrate in deionized water in a preset ratio to form a graphene quantum dot solution includes: First, dissolve the graphene quantum dots in the deionized water according to the mass ratio of the deionized water to the graphene quantum dots being 1:7-13; Then, add the zinc nitrate. Among them, the mass ratio of the deionized water to the zinc nitrate is 1:11-21; Finally, heat the mixed liquid of the graphene quantum dots and the zinc nitrate at a temperature of 130-280 °C for 30-80 min to form the graphene quantum dot solution.

6. The method for preparing a humidity sensor according to claim 5, wherein the step of performing plasma treatment on the insulating layer includes: cleaning the insulating layer; performing surface activation treatment on the cleaned insulating layer through plasma. Among them, the surface activation treatment time is 5-15 min, and the power is 20-100 w.

7. The method for preparing a humidity sensor according to claim 5, wherein The filtered graphene quantum dot solution is subjected to film-forming treatment by a spin coater to form a graphene quantum dot layer on the insulating layer, including: The pre-prepared graphene quantum dot solution is aspirated through a syringe. A filter is provided at the needle position of the syringe, and the impurities in the graphene quantum dot solution are filtered through the filter; The graphene quantum dot solution after filtering impurities is dropped onto the insulating layer; The graphene quantum dot solution is uniformly coated on the insulating layer by the spin coater, wherein the rotation speed of the spin coater is 2000 - 5000 rpm, and the rotation time is 30 - 90 s; The graphene quantum dot liquid coated on the insulating layer is baked to evaporate the solvent to form the graphene quantum dot layer, wherein the baking temperature is 60 - 100 °C, and the baking time is 10 - 30 min.

8. The method for preparing a humidity sensor according to claim 5, wherein The sensing unit with an insulating layer on its surface is fixed on the signal processing unit by a silica gel bonding method, the glue thickness is 10 - 50 μm, the curing conditions are 110 - 180 °C, and the time is 15 - 60 min, The insulating layer is provided on the sensing unit by deposition or thermal oxidation.

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