Carbon nanodots-based temperature sensor and preparation method thereof

Abstract

The application provides a carbon nanodot-based temperature sensor and a preparation method thereof. The carbon nanodot-based temperature sensor comprises, from bottom to top, a substrate layer, an interdigital electrode layer and a sensing layer. The sensing layer comprises hydrophilic carbon nanodot particles and an ionic salt. The sensing layer is formed by drop coating of a mixed aqueous solution of the hydrophilic carbon nanodot particles and the ionic salt. The preparation method is simple and easy to implement, and has low cost. The prepared temperature sensor has high sensitivity, high precision and high stability. The sensitivity of the temperature sensor reaches 345951.8%℃ ‑1 .

Description

Technical Field

[0001] This invention relates to the field of temperature sensor technology, and in particular to a carbon nanoparticle-based temperature sensor and its preparation method. Background Technology

[0002] With the continuous development of science and technology and the expanding application fields, the demand for temperature sensors is increasing in various industries. Temperature sensors are widely used in industrial automation, environmental monitoring, medical diagnosis, and other fields, and are of great significance for the accurate monitoring and control of temperature changes.

[0003] Carbon nanodots, as an emerging nanomaterial, possess many excellent properties, such as small size, high specific surface area, and superior photoelectric and thermoelectric properties. In addition to these properties, carbon nanodots also have a large specific surface area and abundant hydrophilic functional groups, enabling them to capture a large number of water molecules. By leveraging the property of desorbing water molecules upon increasing temperature, thereby reducing the material's conductivity, carbon nanodots hold promise for the fabrication of high-performance temperature sensors.

[0004] Therefore, developing a high-performance carbon nanoparticle-based temperature sensor and its fabrication method is of significant scientific research importance and practical application value. This will bring innovative solutions to the field of temperature measurement, improve the accuracy, sensitivity, and response speed of temperature measurements, and promote the advancement and widespread application of temperature sensor technology. Summary of the Invention

[0005] This invention proposes a carbon nanoparticle-based temperature sensor and its preparation method. The preparation method is simple, easy to implement, and low in cost. Moreover, the prepared temperature sensor has high sensitivity, high accuracy, and high stability.

[0006] The technical solution of the present invention is implemented as follows: a carbon nanoparticle-based temperature sensor includes a substrate, interdigitated electrodes and a sensing layer arranged sequentially from bottom to top, wherein the sensing layer includes hydrophilic carbon nanoparticles and ionic salts.

[0007] Furthermore, the hydrophilic carbon nanoparticles have a particle size of 3-5 nm.

[0008] Furthermore, the ionic salt is one or more of sodium chloride, potassium chloride, potassium carbonate, sodium carbonate, sodium bromide, and calcium chloride.

[0009] Furthermore, the substrate is a poly(ethylene terephthalate) substrate.

[0010] Furthermore, the interdigitated electrodes are gold electrodes, with an area of ​​250*500μm and a spacing of 5μm between the interdigitated electrodes.

[0011] A method for fabricating a carbon nanoparticle-based temperature sensor includes the following steps:

[0012] S1. Preparation of an aqueous solution of hydrophilic carbon nanodots;

[0013] S2. At room temperature, add an ionic salt to an aqueous solution of hydrophilic carbon nanodots to obtain a mixed solution;

[0014] S3. Fabricate interdigitated electrodes on the substrate;

[0015] S4. The mixed solution prepared in step S2 is drop-coated onto the interdigitated electrode prepared in step S3 to obtain a carbon nanoparticle-based temperature sensor.

[0016] Further, in step S1, the aqueous solution of hydrophilic carbon nanodots is prepared as follows: 1g of citric acid and 2g of urea are dissolved in 20ml of deionized water, and microwaved for 5 minutes to obtain a brown solid. The brown solid is then dissolved in deionized water and filtered to obtain an aqueous solution of hydrophilic carbon nanodots.

[0017] Furthermore, the mass ratio of ionic salt to hydrophilic carbon nanodots is (1:1) to (5:1), such as 1:1, 2:1, 3:1, 4:1, 5:1, etc.

[0018] Furthermore, in step S3, a layer of gold is deposited on the substrate using magnetron sputtering technology, and then the gold layer is etched into an interdigital shape using photolithography technology to prepare an interdigital electrode.

[0019] The beneficial effects of this invention are:

[0020] This invention uses carbon nanodots as the sensing element and introduces ionic salts to increase the ion concentration on the surface of the carbon nanodots. Temperature is measured by fabricating a sensor based on carbon nanodots / ionic salts and measuring the current of the device.

[0021] The carbon nanoparticle-based temperature sensor of this invention has a simple preparation method, excellent performance, and high sensitivity, reaching 345951.8%℃. -1 It exhibits good stability and a wide detection range. Furthermore, the simple and inexpensive preparation method of carbon nanodots, allowing for large-scale fabrication, is another advantage of this carbon nanodot-based temperature sensor. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, 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.

[0023] Figure 1 This is a schematic diagram of the structure of a carbon nanoparticle-based temperature sensor.

[0024] Figure 2 The voltage-current curves of the carbon nanoparticle-based temperature sensor are shown at different temperatures.

[0025] Figure 3 The curve showing the relative resistance of a carbon nanoparticle-based temperature sensor as a function of temperature.

[0026] Figure 4 Stability testing of carbon nanoparticle-based temperature sensors at different temperatures.

[0027] Figure 5 The image shows the long-term stability test curve of the carbon nanoparticle-based temperature sensor. Detailed Implementation

[0028] 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.

[0029] like Figure 1 As shown, a carbon nanoparticle-based temperature sensor includes a substrate 1, interdigitated electrodes 2, and a sensing layer 3 arranged sequentially from bottom to top. The sensing layer comprises hydrophilic carbon nanoparticles and an ionic salt. The substrate is a polyethylene terephthalate substrate. The interdigitated electrodes are gold electrodes with an interdigitated area of ​​250*500μm and an interdigitated spacing of 5μm. The hydrophilic carbon nanoparticles have a particle size of 3-5nm, and the ionic salt is one or more of potassium chloride, potassium carbonate, sodium carbonate, sodium bromide, and calcium chloride. The sensing layer is formed by drop-coating a mixed aqueous solution of hydrophilic carbon nanoparticles and the ionic salt. In this embodiment, sodium chloride is used as an example to prepare the sensing layer, that is, the sensing layer is formed by drop-coating a mixed aqueous solution of hydrophilic carbon nanoparticles and sodium chloride.

[0030] The method for preparing the carbon nanoparticle-based temperature sensor includes the following steps:

[0031] S1. Preparation of aqueous solutions of hydrophilic carbon nanodots

[0032] Dissolve 1g of citric acid and 2g of urea in 20ml of deionized water, microwave for 5 minutes to obtain a brown solid. Dissolve the brown solid in deionized water and filter out the insoluble solid to obtain an aqueous solution of hydrophilic carbon nanodots with a concentration of 2g / L.

[0033] S2. At room temperature, sodium chloride is added to an aqueous solution of hydrophilic carbon nanodots to obtain a mixed solution, wherein the mass ratio of sodium chloride to hydrophilic carbon nanodots is 2:1.

[0034] S3. Fabrication of interdigitated electrodes on the substrate

[0035] A layer of gold was deposited on the substrate using magnetron sputtering technology. The specific method is as follows: the prepared poly(ethylene terephthalate) substrate was cut into an appropriate size (2×2cm). The poly(ethylene terephthalate) substrate was ultrasonically cleaned in deionized water and alcohol for 10 min respectively. The cleaned poly(ethylene terephthalate) substrate was transferred to a vacuum sputtering stage, and a vacuum was drawn to prepare for sputtering a layer of gold. The sputtering time was 5 min.

[0036] Then, photolithography is used to etch the gold layer into an interdigitated shape, and the gold layer on the poly(diethyl terephthalate) substrate is etched into an interdigitated shape to prepare an interdigitated electrode.

[0037] S4. The mixed solution prepared in step S2 is drop-coated onto the interdigitated electrode prepared in step S3 to obtain a carbon nanoparticle-based temperature sensor.

[0038] The prepared carbon nanoparticle-based temperature sensor was tested under different temperature environments, and the test results are as follows: Figure 2 As shown in the figure, the current of this carbon nanoparticle-based temperature sensor decreases as the temperature increases, meaning the device can calibrate temperature using current values, thus achieving temperature sensing. Furthermore, the relative resistance of the device as a function of temperature is plotted (…). Figure 3 The device's sensitivity was calculated to be as high as 345951.8%℃. -1 .

[0039] The working principle of the carbon nanoparticle-based temperature sensor is as follows:

[0040] Temperature sensing mechanism of the sensor: The desorption of water molecules adsorbed on the surface of carbon nanodots at high temperature reduces the degree of freedom of ions on the surface of carbon nanodots, thereby reducing conductivity. The introduction of sodium chloride increases the ion concentration on the surface of carbon nanodots, thereby improving sensor performance.

[0041] To verify the stability of the carbon nanoparticle-based temperature sensor at different temperatures, its stability was tested at 20℃ and 100℃. The test results are as follows. Figure 4 As shown, the device maintains good stability during periods of fluctuating temperature conditions.

[0042] Figure 5 These are the test results of the carbon nanoparticle-based temperature sensor after 30 days of storage. It can be seen that over the course of a month, the current value of the sensor remained almost constant at different temperature levels, demonstrating the good stability and durability of the carbon nanoparticle-based temperature sensor.

[0043] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A carbon nanoparticle-based temperature sensor, characterized in that: The sensor comprises, from bottom to top, a substrate, interdigitated electrodes, and a sensing layer, wherein the sensing layer comprises hydrophilic carbon nanoparticles and an ionic salt; the mass ratio of the ionic salt to the hydrophilic carbon nanoparticles is (1:1) to (5:1); the sensor is fabricated according to the following method: S1. Prepare an aqueous solution of hydrophilic carbon nanodots; Dissolve 1g of citric acid and 2g of urea in 20ml of deionized water, microwave for 5 minutes to obtain a brown solid, dissolve the brown solid in deionized water and filter to obtain an aqueous solution of hydrophilic carbon nanodots. S2. At room temperature, add an ionic salt to an aqueous solution of hydrophilic carbon nanodots to obtain a mixed solution; S3. Fabricate interdigitated electrodes on the substrate; S4. The mixed solution prepared in step S2 is drop-coated onto the interdigitated electrode prepared in step S3 to obtain a carbon nanoparticle-based temperature sensor.

2. The carbon nanoparticle-based temperature sensor according to claim 1, characterized in that: The hydrophilic carbon nanoparticles have a particle size of 3-5 nm.

3. The carbon nanoparticle-based temperature sensor according to claim 1, characterized in that: The ionic salt is one or more of sodium chloride, potassium chloride, potassium carbonate, sodium carbonate, sodium bromide, and calcium chloride.

4. The carbon nanoparticle-based temperature sensor according to claim 1, characterized in that: The substrate is a poly(ethylene terephthalate) substrate.

5. A carbon nanoparticle-based temperature sensor according to claim 1, characterized in that: The interdigitated electrodes are gold electrodes.

6. A carbon nanoparticle-based temperature sensor according to claim 1, characterized in that, In step S3, a layer of gold is deposited on the substrate using magnetron sputtering technology, and then the gold layer is etched into an interdigital shape using photolithography to prepare an interdigital electrode.

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