Preparation method of electrochemiluminescence conductive hydrogel, hydrogel electrode device and application of hydrogel electrode device

Abstract

The invention belongs to the technical field of conductive hydrogel materials and application thereof, and relates to a preparation method of electrochemiluminescence conductive hydrogel, a hydrogel electrode device and application thereof. The preparation method of the electrochemiluminescence conductive hydrogel comprises the following steps: S1, adding cane sugar and polyvinyl alcohol into water to obtain a mixture A; s2, adding borax, the surface hydroxylated indium tin oxide nanoparticles and tris (2, 2 '-dipyridyl) ruthenium chloride (II) hexahydrate into water to form a mixture B; s3, mixing the mixture A and the mixture B to prepare the electrochemiluminescence conductive hydrogel. The electrochemiluminescence conductive hydrogel disclosed by the invention has good conductivity and unique'water response 'characteristics, and can directly sense the change of the water level by triggering the electrochemiluminescence phenomenon of the electrochemiluminescence conductive hydrogel when the electrochemiluminescence conductive hydrogel is in contact with water, so that the early warning / monitoring of the water level is realized, the early warning result is more timely, and the early warning efficiency is higher.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrochemiluminescent conductive hydrogel materials and their applications, and relates to a preparation method of an electrochemiluminescent conductive hydrogel, a hydrogel electrode device and its applications. Background Art

[0002] The occurrence of flash floods triggered by short-term extreme rainfall has been on the rise in many regions of the world. Flash floods in arid and mountainous regions are more destructive than those in humid regions. The increasing frequency of flash floods worldwide has caused a series of serious adverse consequences, including accidental deaths, waterborne diseases, economic losses and hindrance to sustainable development.

[0003] Early warning systems help to make timely informed decisions and take emergency actions, and are important tools for reducing the negative consequences of catastrophic flood events. However, the suddenness of extreme precipitation, combined with the complex dynamics of flood mechanisms, poses a great challenge to the timely early warning of flash floods.

[0004] Although in recent years, flood early warning systems (FEWS) based on remote sensing technologies such as synthetic aperture radar (SAR) satellites and optical imaging satellites have made great progress, due to the need to be equipped with expensive ground radars, low Earth orbit (LEO) satellites and reanalysis systems, the investment cost of flood early warning is huge; in addition, satellite records are easily distorted by mountain shadows, speckle noise, clouds and insufficient lighting conditions, resulting in untimely warning results and low warning efficiency.

[0005] Therefore, providing a timely and efficient flood early warning system has important economic and social value. Summary of the Invention

[0006] Aiming at the technical problems of untimely warning results and low warning efficiency existing in the existing flood early warning systems, the present invention provides a preparation method of an electrochemiluminescent conductive hydrogel, a hydrogel electrode device and its applications.

[0007] The present invention uses sucrose, polyvinyl alcohol, borax, surface-hydroxylated indium tin oxide nanoparticles and tris(2,2'-bipyridine) ruthenium(II) hexahydrate as main raw materials to prepare an electrochemiluminescent conductive hydrogel under specific ratios. It has good electrical conductivity and unique "water response" characteristics. By triggering the electrochemiluminescent phenomenon of the electrochemiluminescent conductive hydrogel when it comes into contact with water, it can directly sense the change of water level, so as to realize the early warning / monitoring of water level, with more timely warning results and higher warning efficiency.

[0008] In order to achieve the above object, the technical solution adopted by the present invention is:

[0009] A preparation method of an electrochemiluminescent conductive hydrogel, comprising the following steps:

[0010] S1. Add sucrose and polyvinyl alcohol to water at a mass ratio of (1 - 2):(3 - 5), heat and stir evenly to obtain mixture A;

[0011] S2. Dissolve borax, surface - hydroxylated indium tin oxide nanoparticles and tris(2,2’ - bipyridine) ruthenium(II) hexahydrate in water at a mass ratio of (1 - 2):(1 - 2):(0.03 - 0.05), and heat to form mixture B;

[0012] S3. Mix mixture A from step S1 and mixture B from step S2 to prepare an electrochemiluminescent conductive hydrogel.

[0013] Further defined, in step S1, the specific process of obtaining mixture A is as follows:

[0014] First, dissolve sucrose in water to obtain a sucrose solution; then add polyvinyl alcohol to the sucrose solution; then heat to boiling, and then cool to 90°C - 95°C and stir for 1h - 3h to obtain a translucent viscous mixture A.

[0015] Further defined, in step S2, the heating temperature is 90°C - 95°C.

[0016] Further defined, in step S2, the surface - hydroxylated indium tin oxide nanoparticles are obtained by suspending indium tin oxide nanoparticles in a potassium hydroxide solution, and then successively performing ultrasonic dispersion, washing, centrifugation and drying.

[0017] Further defined, the mass - to - volume ratio of the indium tin oxide nanoparticles to the potassium hydroxide solution is 1g:50mL, the concentration of the potassium hydroxide solution is 1mol / L; the average particle size of the indium tin oxide nanoparticles is 30nm.

[0018] In one embodiment of the present invention, an electrochemiluminescent conductive hydrogel prepared by using the preparation method of the electrochemiluminescent conductive hydrogel.

[0019] In one embodiment of the present invention, the application of the electrochemiluminescent conductive hydrogel as an electrode material in water level early warning / monitoring.

[0020] In one embodiment of the present invention, a hydrogel electrode device includes a cathode, an anode and a gel electrode sheet; the gel electrode sheet is located between the cathode and the anode, and the gel electrode sheet is in contact with the conductive surfaces of the cathode and the anode respectively; both the cathode and the anode are FTO electrodes; the gel electrode sheet is made of the electrochemiluminescent conductive hydrogel.

[0021] Further defined, among the cathode and the anode, one is a serrated FTO electrode and the other is a strip-shaped FTO electrode; a gel electrode sheet is provided on each cusp of the conductive surface of the serrated FTO electrode.

[0022] In one embodiment of the present invention, the application of the hydrogel electrode device as a monitoring element in water level early warning / monitoring.

[0023] Compared with the prior art, the beneficial effects of the present invention are:

[0024] 1. The present invention uses sucrose, polyvinyl alcohol, borax, surface-hydroxylated indium tin oxide nanoparticles, and tris(2,2'-bipyridine) ruthenium(II) hexahydrate as main raw materials to prepare an electrochemiluminescent conductive hydrogel under specific ratios, which has good conductivity and unique "water response" characteristics. When using the electrochemiluminescent conductive hydrogel as the core response material for water level monitoring, through the electrochemiluminescent phenomenon triggered when contacting water, it can directly sense the change of water level, and there is no need for additional physical contact or complex mechanical structure, and the early warning result is more timely and the early warning efficiency is higher.

[0025] 2. The hydrogel electrode device provided by the present invention includes a cathode, an anode, and a gel electrode sheet; and one of the cathode and the anode is designed as a serrated FTO electrode. The FTO (fluorine-doped tin oxide) electrode is selected as the working electrode because of its excellent conductivity and chemical stability; the serrated structure design not only allows water to enter the core material hydrogel based on capillary action, but also ensures the accuracy and precision of different water level monitoring.

[0026] 3. The hydrogel electrode device of the present invention integrates the cathode, the anode, and the gel electrode sheet into a monitoring element, with a simple structure and convenient use, simplifies the complexity of the existing water level monitoring equipment, and reduces costs. Description of the Drawings

[0027] Figure 1 Schematic diagram for the production of the gel electrode sheet;

[0028] Figure 2 Schematic diagram for the production of the hydrogel electrode device;

[0029] Figure 3 Schematic diagram for the conductivity detection of the conductive hydrogel;

[0030] Figure 4 Schematic diagram for the resistance measurement of the conductive hydrogel;

[0031] Figure 5 Relationship between water content and resistance of the conductive hydrogel before and after stretching;

[0032] Figure 6Relationship between the measured distance and resistance of the conductive hydrogel;

[0033] Figure 7 Schematic diagram for measuring the ductility of the conductive hydrogel;

[0034] Figure 8 Relationship between the water content and tensile elongation of the conductive hydrogel;

[0035] Figure 9 Relationship between the water content and recoverability of the conductive hydrogel;

[0036] Figure 10 Schematic connection diagram for the study of the electrochemiluminescence performance of the conductive hydrogel;

[0037] Figure 11 Luminescence phenomenon after contact of different volumes of deionized water with the hydrogel electrode device;

[0038] Figure 12 Scatter plot of the electrical signal intensity in the luminescent area of the conductive hydrogel electrode after contact of different volumes of deionized water with the hydrogel electrode device;

[0039] Figure 13 Relationship between the measurement position of different volumes of deionized water and the luminescence situation;

[0040] Figure 14 Luminescence phenomenon after contact of different volumes of muddy water with the hydrogel electrode device;

[0041] Figure 15 Scatter plot of the electrical signal intensity in the luminescent area of the conductive hydrogel electrode after contact of different volumes of muddy water with the hydrogel electrode device;

[0042] Figure 16 Relationship between the measurement position of different volumes of muddy water and the luminescence situation;

[0043] Figure 17 Electrochemiluminescence-time curve of the hydrogel at different voltages;

[0044] Figure 18 Electrochemiluminescence-time curve of hydrogels with different thicknesses;

[0045] Figure 19 Physical diagram of the flash flood warning simulation device formed by using the hydrogel electrode device as a monitoring element;

[0046] Figure 20 Physical diagram of the change in the muddy water level and the luminescence situation of the hydrogel electrode device. Specific implementation mode

[0047] The technical solution of the present invention will be further described below in conjunction with the accompanying drawings and embodiments, but the present invention is not limited to the following implementation cases.

[0048] Unless otherwise defined, technical terms or scientific terms used in the present invention shall have the ordinary meanings as understood by those of ordinary skill in the art to which the present invention pertains.

[0049] Technologies, methods, and devices known to those of ordinary skill in the relevant fields may not be discussed in detail, but where appropriate, such technologies, methods, and devices shall be regarded as part of the specification.

[0050] It should also be understood that the specific embodiments described above are only used to explain the present invention, and the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, making equivalent substitutions or changes, shall be covered by the protection scope of the present invention.

[0051] The research and development idea of the present invention is to use sucrose, polyvinyl alcohol, borax, surface-hydroxylated indium tin oxide nanoparticles, and tris(2,2'-bipyridine) ruthenium(II) hexahydrate as the main raw materials, and prepare an electrochemiluminescent conductive hydrogel under specific ratios, and utilize its good conductivity and unique "water response" characteristics to achieve early warning / monitoring of water levels.

[0052] The electrochemiluminescent conductive hydrogel formed by the present invention combines the characteristics of conductive hydrogels and electrochemiluminescent hydrogels. A conductive hydrogel is a hydrogel material with conductivity made by adding a conductive medium to a hydrogel. It combines the conductive properties of conductive polymers and the flexibility of hydrogels, etc., and has a large specific surface area, excellent electron transport and ion transport capabilities, etc., and can be used as an electrode material for preparing flexible supercapacitors or batteries, and then form a hydrogel electrode device for water level early warning / monitoring. At the same time, electrochemiluminescent hydrogels have the advantages of high sensitivity, easy control, and simple instrumentation of electrochemiluminescence (ECL) technology, as well as the biochemical characteristics of inherent flexible conductive materials and hydrogels. Therefore, by combining conductive hydrogel materials with electrochemiluminescence, an electrochemiluminescent conductive hydrogel is developed for alarm of catastrophic mountain floods, which not only realizes timely and efficient water level early warning / monitoring, but also simplifies the monitoring process and reduces the input cost of early warning devices.

[0053] The following reagents and instruments are used in the embodiments of the present invention.

[0054] 1. Reagents

[0055] Polyvinyl alcohol (abbreviation: PVA; chemical formula: [C2H4O] n ; CAS number: 9002-89-5)

[0056] Sucrose (chemical formula: C 12 H 22 O11 ; CAS No.: 57-50-1; Mw: 342.297 g / mol)

[0057] Borax (chemical formula: Na2B4O7·10H2O; CAS No.: 1303-96-4; Mw: 381.37 g / mol) Indium tin oxide nanoparticles (abbreviation: ITO; chemical formula: In2O3·SnO2; CAS No.: 50926-11-9)

[0058] Tris(2,2'-bipyridine)ruthenium(II) hexahydrate (CAS No.: 50525-27-4; Mw: 748.6 g / mol) Ultra-pure water

[0059] 2. Instruments

[0060] Glass rod, magnetic stirring electrothermal mantle, balance, spatula, ultrasonic cleaner, measuring cylinder, beakers (250 mL; 50 mL), watch glass (90 mm), digital multimeter, scalpel, ruler, timer, conductive pen, spring clip, FTO electrode (1.5 cm × 1.55 cm strip, 2 cm × 10 cm strip, 2 cm × 10 cm serrated), hole punch (punching diameter 6 mm), scalpel, ruler, timer, conductive pen, double-sided tape, spring clip, Apple iPhone 13 mobile phone (wide-angle camera - 26 mm f 1.6), macro lens, blue LED, and power-on device (composed of 3 1.5V Nanhua batteries and 2 contact clips).

[0061] Example 1

[0062] This example provides a preparation method of an electrochemiluminescence conductive hydrogel, which includes the following steps:

[0063] S1. Dissolve sucrose and polyvinyl alcohol (PVA) in water respectively, and stir evenly to obtain mixture A;

[0064] In this example, the preparation process of mixture A is as follows:

[0065] First, take 1.1024 g of sucrose and 50 mL of ultra-pure water, add the water to the sucrose, and then stir until completely dissolved to obtain a sucrose solution;

[0066] Weigh 4.0010 g of polyvinyl alcohol PVA solid and add it to the above sucrose solution and stir; then place the obtained mixed solution on a rotary magnetic stirrer, and adjust the temperature of the rotary magnetic stirring electrothermal mantle to the maximum, heat and keep stirring; when the mixed solution is close to boiling, adjust the temperature to 95 °C (the lowest is 90 °C), continue to stir for 2 h until the mixture becomes semi-transparent and viscous, turn down the temperature for standby, and obtain mixture A.

[0067] S2. Add borax, surface-hydroxylated indium tin oxide nanoparticles, and tris(2,2'-bipyridine)ruthenium(II) hexahydrate into water, and dissolve them completely to form mixture B.

[0068] In this example, the surface-hydroxylated indium tin oxide nanoparticles: 1.0 g of indium tin oxide nanoparticles (ITO) were added into 50 mL of 1.0 mol / L potassium hydroxide (KOH) solution, and the mixture was rotated and mixed evenly for 12 h, then washed three times with distilled water, centrifuged, and dried to obtain the solid.

[0069] Preferably, the average particle size of the indium tin oxide nanoparticles is 30 nm.

[0070] In this example, the specific process of forming mixture B is as follows:

[0071] Weigh 1.0243 g of borax, 1.5773 g of surface-hydroxylated indium tin oxide nanoparticles, and 0.0374 g of tris(2,2'-bipyridine)ruthenium(II) hexahydrate and put them into a beaker. Measure 50 mL of ultrapure water with a measuring cylinder and add it to the beaker. Stir continuously and disperse it ultrasonically with an ultrasonic cleaner for five minutes to completely dissolve tris(2,2'-bipyridine)ruthenium(II) hexahydrate and evenly disperse the surface-hydroxylated indium tin oxide nanoparticles in the solution. Place the beaker on a magnetic stirring hotplate, heat it while stirring continuously. When the heating temperature reaches 95 °C, mixture B is obtained.

[0072] S3. Mix the mixture A in step S1 and the mixture B in step S2 to prepare an electrochemiluminescence conductive hydrogel.

[0073] Specifically: Pour mixture B into mixture A, continue heating and stirring until the solution becomes viscous and there are no particles, and the obtained jelly-like substance is the electrochemiluminescence conductive hydrogel, also known as the conductive hydrogel doped with ITO-Ru(bpy)3Cl2, abbreviated as hydrogel or ECL gel.

[0074] Further cool the ECL gel, then pour it into a petri dish with a diameter of 90 mm, seal it with plastic wrap, and store it in the refrigerator.

[0075] The electrochemiluminescence conductive hydrogel prepared in this example has good conductivity and unique "water response" characteristics, and can be used as an electrode material for water level monitoring.

[0076] In the above Example 1, sucrose and polyvinyl alcohol can be arbitrarily selected and replaced within the mass ratio range of (1 - 2):(3 - 5). Exemplarily, the mass ratio of sucrose to polyvinyl alcohol can be 1:3, 1:4, 1:5, 2:3, 2:4, or 2:5.

[0077] In the above Example 1, the mass ratio of borax, surface-hydroxylated indium tin oxide nanoparticles, and tris(2,2'-bipyridine) ruthenium(II) hexahydrate can be arbitrarily selected and replaced within the range of (1-2):(1-2):(0.03-0.05). Exemplarily, the mass ratios of borax, surface-hydroxylated indium tin oxide nanoparticles, and tris(2,2'-bipyridine) ruthenium(II) hexahydrate are (1:1:0.03), (1:1:0.05), (1:2:0.03), (1:2:0.05), (2:1:0.03), (2:1:0.05), (2:2:0.03), or (2:2:0.05).

[0078] In the above Example 1, the heating temperature can be arbitrarily selected and replaced within the range of 90°C to 95°C; the stirring time can be arbitrarily selected and replaced within the range of 1 h to 3 h. Exemplarily, the heating temperature is 90°C, 91°C, 92°C, 93°C, or 94°C; the stirring time is 1 h, 1.5 h, 2.5 h, or 3 h.

[0079] After arbitrarily selecting and replacing the material ratios and preparation parameters in Example 1, an electrochemiluminescence conductive hydrogel (ECL gel) with similar or identical performance to that of Example 1 can be obtained, which is used for timely and efficient early warning / monitoring of water levels.

[0080] Example 2

[0081] The purpose of this example is to fabricate a hydrogel electrode device using the electrochemiluminescence conductive hydrogel in Example 1.

[0082] In this example, the hydrogel electrode device includes a cathode, an anode, and a gel electrode sheet; the gel electrode sheet is located between the cathode and the anode, and the gel electrode sheet is in contact with the conductive surfaces of the cathode and the anode respectively.

[0083] In this example, both the cathode and the anode are FTO electrodes; the gel electrode sheet is made of the electrochemiluminescence conductive hydrogel prepared in Example 1.

[0084] In this example, the FTO electrode refers to an optical electrode coated with an FTO coating.

[0085] See Figure 1 , in this example, the manufacturing method of the gel electrode sheet is as follows:

[0086] Step 1: Weigh 0.6 g of the ECL gel stored under cooling and place it between two glass slides; the ECL gel is the electrochemiluminescence conductive hydrogel prepared in Example 1;

[0087] Step 2: Fix the two glass slides with a spring clip and press for 10 min - 15 min to form the ECL gel into a thin sheet;

[0088] Step 3: After loosening the bulldog clip, remove the glass slide, and air-dry the flaky ECL gel at room temperature;

[0089] Step 4: Then place the air-dried ECL gel pressed into a flaky shape between two pieces of A4 paper, and use a hole punch to cut it into circular flakes with a diameter of 6 mm, which are the gel electrode sheets, also known as ECL gel electrodes.

[0090] In this embodiment, among the cathode and the anode, one is a serrated FTO electrode and the other is a strip-shaped FTO electrode; a gel electrode sheet is arranged on each tooth of the conductive surface of the serrated FTO electrode.

[0091] See Figure 2 , the preparation method of the hydrogel electrode device provided in this embodiment is as follows:

[0092] 1) Before manufacturing the electrode device, use an electronic digital micrometer to measure the thickness of the ECL gel electrode;

[0093] 2) Place the prepared circular ECL gel between two FTO electrodes; one is a 2 cm × 10 cm serrated FTO electrode, and place the gel electrode sheet at the protruding part of the serrated conductive surface; then place the conductive surface of another 2 cm × 10 cm strip-shaped FTO electrode downward in contact with the gel electrode sheet, and paste double-sided tape between the two FTO electrodes to fix the position to form a hydrogel electrode device.

[0094] The hydrogel electrode device formed in this embodiment can be used as a monitoring element for water level monitoring. Specifically, the input end and the output end of the power supply are electrically connected to the cathode and the anode on the hydrogel electrode device one by one. The formed ECL gel electrode device can be used for river water level monitoring or flash flood warning.

[0095] Next, experimental studies are carried out on the performance of the above-prepared electrochemiluminescence conductive hydrogel and the hydrogel electrode device. At the same time, in order to highlight the technical advantages of the electrochemiluminescence conductive hydrogel of the present invention in water level monitoring, the following comparative examples are designed.

[0096] Comparative Example

[0097] The preparation method of the conductive hydrogel provided in this comparative example includes the following steps:

[0098] S1: Dissolve sucrose and polyvinyl alcohol (PVA) in water respectively to prepare a mixture A;

[0099] First, take 1.1024 g of sucrose and 50 mL of ultrapure water, add the water to the sucrose, and then stir until completely dissolved to obtain a sucrose solution;

[0100] Weigh 4.0010 g of polyvinyl alcohol (PVA) solid and add it to the above-mentioned sucrose solution, then stir; next, place the obtained mixed solution on a rotary magnetic stirrer and adjust the temperature of the rotary magnetic stirrer with electric heating jacket to the maximum, heat and keep stirring; when the mixed solution is close to boiling, adjust the temperature to 95 °C, continue stirring for 2 h until the mixture becomes semi-transparent and viscous, turn down the temperature for standby to obtain mixture A;

[0101] S2. Prepare mixture B from borax and surface-hydroxylated ITO nanoparticles;

[0102] In this example, the surface-hydroxylated indium tin oxide nanoparticles are obtained by adding 1.0 g of indium tin oxide nanoparticles (ITO) to 50 mL of 1.0 mol / L potassium hydroxide (KOH) solution, rotating and mixing for 12 h, then washing three times with distilled water, centrifuging and drying.

[0103] The particle size of the indium tin oxide nanoparticles is 30 nm.

[0104] Weigh 1.0243 g of borax and 1.5773 g of surface-hydroxylated ITO nanoparticles and put them into a beaker. Measure 50 mL of ultrasonic water with a measuring cylinder and add it to the beaker, keep stirring, and disperse them ultrasonically for 5 min with an ultrasonic cleaner to make the surface-hydroxylated indium tin oxide nanoparticles evenly dispersed in the solution; place the beaker on a magnetic stirrer with electric heating jacket and heat while stirring continuously. When the heating temperature reaches 95 °C, obtain mixture B.

[0105] S3. Mix mixture A from step S1 and mixture B from step S2 to prepare the conductive hydrogel ITO.

[0106] Specifically, pour mixture B into mixture A, continue heating and stirring; until the solution becomes viscous and there are no particles, forming a gel-like substance, which is the conductive hydrogel doped with ITO. When the conductive hydrogel cools slightly, pour it into a 90 mm petri dish, seal it with plastic wrap, and store it in a 4 °C refrigerator.

[0107] Furthermore, the following tests are carried out to characterize the performance of the electrochemiluminescent conductive hydrogel (hereinafter referred to as conductive hydrogel) and the hydrogel electrode device.

[0108] Test 1. Conductivity characterization of the conductive hydrogel

[0109] Use a scalpel to cut a piece of the conductive hydrogel prepared in Example 1, contact both ends of the instrument with the conductive hydrogel, and the small lamp connected emits blue light; separate the conductive hydrogel in the middle, the small lamp does not emit light; then contact the separated hydrogels, and the small lamp emits blue light again (see Figure 3 ).

[0110] Test 2. Resistance characterization of the conductive hydrogel

[0111] The conductive hydrogels prepared in Example 1 and the comparative example were used as test samples to characterize the resistance before and after stretching.

[0112] Six pieces were taken from each of the above two test samples, and the mass of each was 1.5 g. For each test sample, one piece was used as the conductive hydrogel with 100% water content, and the other five pieces were numbered and weighed, and then placed in an oven with a temperature set at 90 °C to dry off the water. The weight of the conductive hydrogel after drying was calculated by the water content formula. After drying for a period of time, the conductive hydrogel was weighed to obtain conductive hydrogels with water contents of 89%, 78%, 67%, 56%, and 45%.

[0113] The water content of the conductive hydrogel was calculated by the following formula:

[0114] Water content of conductive hydrogel = (weight after drying / original weight) × 100%

[0115] Then, in accordance with Figure 4 the method, the resistance before stretching and the resistance after stretching of the conductive hydrogels with different water contents of the two test samples were measured.

[0116] During the test, the measuring terminals of the digital multimeter were inserted into both ends of the conductive hydrogel (see the schematic diagram on the right in Figure 4 ). When the value was stable, the data was recorded as the resistance of the conductive hydrogel before stretching. When the conductive hydrogel with different water contents was stretched to the same length, a resistance measurement was performed again. When the value was stable, the data was recorded as the resistance of the conductive hydrogel after stretching.

[0117] After the test, for the hydrogels with different water contents, the resistance before stretching and the resistance after stretching are shown in Table 1 and Table 2, and the obtained line graph is shown in Figure 5 .

[0118] Table 1 Data of water content of conductive hydrogel and resistance before stretching

[0119] Water content 100％ 89％ 78％ 67％ 56％ 45％ Example 1 102.1 98.8 92.8 88 94.6 95.7 Comparative example 122.0 106.5 98.8 90.1 95.4 98.7

[0120] Table 2 Data of water content of conductive hydrogel and resistance after stretching

[0121] Water content 100％ 89％ 78％ 67％ 56％ 45％ Example 1 110.2 108.3 99.6 94.8 97.1 98.5 Comparative example 140.0 115.4 102.8 98.6 102.3 107.4

[0122] From Table 1, Table 2 and Figure 5It can be seen that for the two test samples, the resistance before and after stretching decreases first with the decrease of water content, reaches the lowest point and then increases. The resistance of the two test samples before and after stretching is the smallest when the water content is 67%, that is, the conductivity of the two conductive hydrogels is the best when the water content of the hydrogel is 67%; at the same time, for the conductive hydrogel of the comparative example, the resistance before stretching and the resistance after stretching are both greater than the resistance corresponding to Example 1, indicating that the electrochemiluminescence conductive hydrogel of the present invention has better conductivity.

[0123] Take a piece of the conductive hydrogel prepared in Example 1, stretch its length to 7 cm, fix one end and insert it into one end of a digital multimeter, and measure the other end of the digital multimeter at 1 cm, 2 cm, 3 cm, 4 cm, 5 cm, 6 cm and 7 cm of the hydrogel respectively (see Figure 4 left). After the value is stable, record the resistance value. The resistance data is shown in Table 3, and the obtained dot-line graph is as Figure 6 .

[0124] From Table 3 and Figure 6 it can be seen that when at different positions from 1 cm to 7 cm, the resistance of the conductive hydrogel varies between 100 KΩ - 140 KΩ. And with the increase of the resistance measurement distance, the resistance value of the conductive hydrogel first increases and then decreases, and the growth rate is greater than the decrease rate.

[0125] Table 3 Resistance values at different measurement distances

[0126] Distance (cm) 7 6 5 4 3 2 1 Example 1 122.1 128.3 122.2 136.8 131 122.1 102.1

[0127] Experiment 3. Characterization of the ductility of the conductive hydrogel

[0128] Use the conductive hydrogels prepared in Example 1 and the comparative example as test samples to characterize the ductility of the conductive hydrogel.

[0129] The test method is as follows: for the two test samples, refer to the method of Experiment 2 to obtain conductive hydrogel samples with water contents of 100%, 89%, 78%, 67%, 56%, and 45%.

[0130] See Figure 7 , for the conductive hydrogel samples with different water contents, one end is aligned with the zero scale line of the ruler, measure the original length L of the conductive hydrogel, and stretch the section that is not aligned with the zero scale line of the ruler in the opposite direction of the zero scale line to obtain the length L of the stretched conductive hydrogel 末 . Let go, time for 2 minutes to allow the conductive hydrogel to recover freely, and record the length of the conductive hydrogel as L 恢 after 2 minutes.

[0131] Calculate the tensile elongation rate and recoverability of the conductive gel according to the following formula.

[0132] Elongation length ΔLe = L 末 - L

[0133] Contraction length ΔLc = L 恢 –L 末

[0134] Tensile elongation ε = (ΔLe / L) × 100%

[0135] Recovery r = (ΔLc / ΔLe) × 100%

[0136] (1) Tensile elongation results

[0137] The tensile elongation data of the two test samples at different water contents are shown in Table 4, and the obtained line chart is shown in Figure 8 .

[0138] From Table 4 and Figure 8 it can be seen that for the conductive hydrogels prepared in Example 1 and the comparative example, with the decrease of water content, the tensile elongation first increases, and reaches the highest value at a water content of 67%. Then, with the further decrease of water content, the tensile elongation decreases. Among them, the tensile elongation of the conductive hydrogel prepared in Example 1 at each water content is higher than that of the conductive hydrogel of the comparative example. This shows that the conductive hydrogel prepared in Example 1 has better tensile elongation.

[0139] Table 4 Water content and tensile elongation data of conductive hydrogel

[0140] Water content 100％ 89％ 78％ 67％ 56％ 45％ Example 1 120.0％ 130.0％ 179.3％ 243.5％ 56.0％ 43.5％ Comparative example 114.3％ 115.0％ 125.5％ 155.0％ 35.3％ 33.3％

[0141] (2) Recovery

[0142] The recovery data of the two test samples at different water contents are shown in Table 5, and the obtained line chart is shown in Figure 9 .

[0143] Table 5 Water content and recovery data of conductive hydrogel

[0144] Water content 100％ 89％ 78％ 67％ 56％ 45％ Example 1 38.9％ 66.7％ 82.7％ 92.9％ 42.9％ 30.0％ Comparative example 6.6％ 34.8％ 58.3％ 86.2％ 33.3％ 20.0％

[0145] From Table 5 and Figure 9 it can be seen that for the conductive hydrogels prepared in Example 1 and the comparative example, their recoveries both increase with the decrease of water content, reach the highest value at a water content of 67%, and then decrease with the further decrease of water content. For the conductive hydrogel of the comparative example, the difference in recovery with the change of water content is greater than that of the conductive hydrogel of Example 1. This shows that the conductive hydrogel prepared in Example 1 has better recovery.

[0146] In summary, the conductive hydrogel prepared in this example has better tensile elongation and recovery, indicating that it has excellent ductility.

[0147] Experiment 4: Study on the Electrochemiluminescence Behavior of Conductive Hydrogels

[0148] The purpose of this experiment is to study the electrochemiluminescence behavior of conductive hydrogels using the gel electrode sheet prepared in Example 2.

[0149] 4.1 Study on the Luminescence Phenomenon after Different Volumes of Deionized Water Contact with the Gel Electrode Sheet

[0150] Take a 1.5 cm × 1.5 cm FTO electrode (electrode A) with the conductive surface facing up, and transfer different volumes (0 μL, 1 μL, 2 μL, 3 μL, 4 μL, 5 μL, 6 μL) of deionized water onto the conductive surface. Place the hydrogel electrode sheet prepared in Example 1 on the deionized water and let it stand for 1 min. Take another FTO electrode (electrode B) and make its conductive surface contact the hydrogel electrode sheet. Slightly stagger the two FTO electrodes and fix the positions of the two FTO electrodes with double-sided tape. After standing for 1 min, connect the two ends of the power supply device to the two corresponding FTO electrodes respectively (the positive pole of the power supply device is connected to electrode B, and the negative pole of the power supply device is connected to electrode A), as Figure 10 shown. Fix a macro lens on the mobile phone camera, then fix the mobile phone, and use the mobile phone camera to observe and take pictures. Then make the test environment completely dark, turn on the mobile phone camera, turn on the switch of the power supply device, observe the luminescent area of the hydrogel electrode sheet, and take pictures (exposure time 5 s). Observe the electrochemiluminescence intensity signals of the hydrogel electrode sheet under different volumes of deionized water, as Figure 11 shown.

[0151] From Figure 11 it can be seen that when the volume of deionized water is 3 μL and 4 μL, the electrochemiluminescence phenomenon of the hydrogel electrode sheet is better. Using conventional processing techniques, the pictures taken are processed by Image J software to obtain the average fluorescence intensity data of the luminescent area of the hydrogel electrode sheet in Table 6. Then use Origin software to plot the data in Table 6 to obtain a scatter plot, as shown in Figure 12 .

[0152] In addition, the pictures are processed by Image J software to obtain the data of distance and luminescence situation, and plotted by Origin, as shown in Figure 13 shown.

[0153] Table 6 Average Fluorescence Intensity of the Luminescent Area of the Hydrogel Electrode Sheet under Different Volumes of Deionized Water

[0154] Volume of water μL 1 2 3 4 5 6 Average fluorescence intensity 16 24 53 65 31 47

[0155] See Figure 12 , Figure 13It was found from Table 6 that when the gel electrode sheet comes into contact with deionized water, a luminescence phenomenon will occur; preferably, when the volume of deionized water is 4 μL, the average electrochemiluminescence intensity of the luminescent region of the hydrogel electrode sheet is the largest.

[0156] 4.2. Study on the Luminescence Phenomenon after Different Volumes of Muddy Water Contact with the Gel Electrode Sheet

[0157] Take the soil from the campus greening area and put it into a beaker. Dry the soil in an oven and pick out the large pieces that are not easy to break up. Weigh 0.5 g of the finer ground soil into a beaker and add deionized water to completely dissolve it to obtain muddy water.

[0158] Take a 1.5 cm × 1.5 cm ITO electrode (electrode A) with the conductive surface facing up, transfer different volumes (1 μL, 2 μL, 3 μL, 4 μL, 5 μL, 6 μL) of muddy water to the conductive surface, place the gel electrode sheet on the muddy water, and let it stand for 1 min. Take another ITO electrode (electrode B) of the same size with the conductive surface in contact with the gel electrode sheet. The two ITO electrodes are slightly staggered left and right, and the positions of the two ITO electrodes are fixed with double-sided tape. After standing for 1 min, connect the two ends of the power-on device to the two corresponding ITO electrodes respectively (the positive pole of the power-on device is connected to electrode A). Fix a macro lens on the mobile phone lens, fix the position of the mobile phone, and use the mobile phone camera to observe and take pictures. Turn off the lights to make the experimental environment completely dark, turn on the mobile phone camera, turn on the switch of the power-on device, observe the luminescent region of the conductive hydrogel electrode, and take pictures (exposure time 5 s).

[0159] After different volumes of muddy water come into contact with the gel electrode sheet, different electrochemiluminescence behaviors are observed, as Figure 14 shown.

[0160] From Figure 14 it can be seen that when the volume of muddy water is 3 μL and 4 μL, the electrochemiluminescence phenomenon of the gel electrode sheet is better. After processing the taken pictures with Image J software, the average fluorescence intensity data of the luminescent region of the gel electrode sheet are shown in Table 7. The scatter plot obtained by plotting the data in Table 7 with Origin is shown in Figure 15 .

[0161] Furthermore, using the existing conventional technology to process the pictures with Image J software, the data of distance and luminescence situation are obtained, and the plot with Origin is as Figure 16 shown.

[0162] Table 7 Average Fluorescence Intensity of the Luminescent Region of the Gel Electrode Sheet under Different Volumes of Muddy Water

[0163] Volume of muddy water μL 1 2 3 4 5 6 Average fluorescence intensity 44 72 110 99 84 90

[0164] See Table 7, Figure 15 andFigure 16 It can be seen that when the gel electrode sheet comes into contact with muddy water, a luminescence phenomenon will occur. And when the volume of the muddy water is 3 μL, the electrochemiluminescence intensity of the luminescent area of the gel electrode sheet is the largest, that is to say, the electrochemiluminescence phenomenon of the gel electrode sheet is the best at this time.

[0165] From the luminescence phenomena after the contact of water (deionized water or muddy water) with different volumes with the gel electrode sheet, it can be seen that the gel electrode sheet can trigger its electrochemiluminescence effect as long as it comes into contact with water. It can be seen that both the electrochemiluminescent conductive hydrogel prepared in the present invention and the formed gel electrode sheet have unique "water response" characteristics, and the water level can be monitored without additional physical contact or complex mechanical structures, and the warning result has good timeliness.

[0166] 4.3 Electrochemiluminescence of the gel electrode sheet under different voltages

[0167] The main purpose of this test is to study the electrochemiluminescence of the gel electrode sheet under different voltages. The specific test steps are as follows:

[0168] (1) Place the prepared circular ECL gel electrode on the FTO-coated optical electrode (15×15×1.1 mm);

[0169] (2) Use a pipette to add 2 μL (a total of 4 μL) of water to both sides of the circular ECL gel electrode, and let it stand for 1 min;

[0170] (3) Take another FTO electrode and make its conductive surface contact with the hydrogel. The two FTO electrodes are slightly staggered, and the positions of the two FTO electrodes are fixed with double-sided tape, and let it stand for 1 min to obtain an ECL gel device;

[0171] (4) When performing ECL measurement, four No. 5 battery (1.5 V) are used as the power supply, and a sliding rheostat is used to adjust the applied voltage;

[0172] (5) Install the ECL gel device into the current loop for ECL measurement. A photomultiplier tube (PMT) is used as the detector;

[0173] (6) Connect the ECL gel and place it in the dark box of the MPI-E type ECL analyzer. The PMT works at a high voltage of -400 V, and the applied potential difference between the anode and the cathode is set to 2.5 V through a sliding rheostat. Use the MPI-E analysis client system software to record the ECL signal. The step pulse method is adopted, and the measurement duration is 300 seconds after the start switch is turned on;

[0174] (7) Click the start button of the MPI-E analysis client system software. After about 5 s, turn on the loop switch connected to the ECL gel device. Disconnect the loop switch at about 300 s, and click the end button;

[0175] (8) Repeat the above steps. When the volume of deionized water is 4 μL, measure the electrochemiluminescence of the ECL gel electrode at voltages of 1.5 V, 2 V, 2.5 V, 3 V, 3.5 V, 4 V, and 4.5 V. The results are as Figure 17 shown.

[0176] See Figure 17 It can be seen that as the voltage increases, the electrochemiluminescence intensity of the ECL gel electrode first increases and then decreases, and its optimal working voltage is 2.5 V, indicating that it has strong electrochemiluminescence intensity at low voltages.

[0177] 4.4 Electrochemiluminescence of gel electrode sheets with different thicknesses

[0178] This experiment mainly tests the electrochemiluminescence of gel electrode sheets with different thicknesses. The specific test steps are as follows:

[0179] (1) Use an electronic digital micrometer to measure the thickness of the circular ECL gel electrode; place the ECL gel electrode with a thickness of 20 μm on the FTO-coated optical electrode (15 × 15 × 1.1 mm);

[0180] (2) Use a pipette to add 2 μL (a total of 4 μL) of water to both sides of the ECL gel electrode and let it stand for 1 min; take another FTO electrode and make its conductive surface contact the hydrogel. The two FTO electrodes are slightly staggered, and the positions of the two FTO electrodes are fixed with double-sided tape and left standing for 1 min to obtain the ECL gel device; when performing ECL measurement, four Nanfu batteries (1.5 V) are used as the power supply, and a sliding rheostat is used to adjust the applied voltage; connect the ECL gel device to the current loop for ECL measurement; a photomultiplier tube (PMT) is used as the detector;

[0181] (3) Place the ECL gel device in the dark box of the MPI-E ECL analyzer. The PMT works at a high voltage of -400 V, and the applied potential difference between the anode and the cathode is set to 2.5 V through a sliding rheostat. Use the MPI-E analysis client system software to record the ECL signal. Using the step pulse method, measure the duration for 300 seconds after starting the switch;

[0182] (4) Click the start button of the MPI-E analysis client system software. Open the loop switch connected to the ECL gel device about 5 s later, disconnect the loop switch about 300 s later, and click the end button;

[0183] (5) Repeat the above steps. When the volume of deionized water is 4 μL and the voltage is 2.5 V, measure the electrochemiluminescence at thicknesses of 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, and 50 μm respectively. The results are asFigure 18 as shown

[0184] See Figure 18 It can be seen that: as the thickness of the hydrogel increases, the electrochemiluminescence intensity first increases and then decreases, and when the hydrogel thickness is 30 μm to 35 μm, it has better electrochemiluminescence intensity.

[0185] Through the above tests, the electrochemiluminescence conductive hydrogel and gel electrode sheet prepared by the present invention have excellent electrochemiluminescence characteristics and unique "water response" characteristics. These characteristics enable the gel electrode sheet to show higher warning efficiency and more timely warning results when performing water level warning monitoring.

[0186] Experiment 5: Application of Hydrogel Electrode Device in Warning / Detecting Muddy Water at Different Depths

[0187] The purpose of this experiment is to study the warning / monitoring of muddy water at different depths using the hydrogel electrode device provided in Example 2.

[0188] Weigh 0.5 g of finer ground soil into a 250 mL beaker, add deionized water to completely dissolve it to obtain a portion of muddy water. Use the hydrogel electrode device provided in Example 2 as the monitoring element to warn / monitor the muddy water level.

[0189] See Figure 19 , the test process is as follows: Fix the hydrogel electrode device on the inner wall of a 100 mL beaker, making it as close to the inner wall as possible. Connect the two ends of the power supply device to the electrodes at both ends of the hydrogel electrode device correspondingly. Fix the position of the mobile phone outside the beaker. On the side far from the hydrogel electrode device, add muddy water to the beaker until it covers the serrated protrusion of the first circular gel electrode sheet; then turn off the light to make the test environment completely dark. Turn on the mobile phone camera and turn on the power supply device switch, observe the light-emitting area of the gel electrode sheet, and take a photo (exposure time 5 s). Turn on the light, and then add muddy water until it covers the serrated protrusion of the second circular gel electrode sheet; turn off the light to make the test environment completely dark; turn on the mobile phone camera and turn on the power supply device switch, observe the light-emitting area of the gel electrode sheet, and take a photo. Repeat this operation until the muddy water covers the serrated protrusion of the last circular gel electrode sheet. Turn off the light to make the test environment completely dark; turn on the mobile phone camera and turn on the power supply device switch, observe the light-emitting area of the gel electrode sheet, and take a photo. The images obtained during the above test process are as Figure 20 as shown

[0190] Observe Figure 20As can be seen from the images, as the muddy water level rises, the gel electrode sheets submerged in the muddy water will all emit light in the dark environment. This indicates that the hydrogel electrode device provided in this embodiment can give early warnings / monitor different depths of muddy water, with a high warning effect.

[0191] The above performance verification was carried out with the electrochemiluminescence conductive hydrogel prepared in Example 1. When the mass ratios of various raw materials and reaction parameters are arbitrarily selected and replaced within the scope defined by the claims of the present invention during the preparation process, the prepared electrochemiluminescence conductive hydrogel exhibits performance similar to or the same as that of Example 1 of Example 1, has good electrical conductivity and unique "water response" characteristics, and will trigger an electrochemiluminescence phenomenon when it comes into contact with water. When used for early warning / monitoring of water levels, the warning results are more timely and the warning efficiency is higher.

[0192] Obviously, the above embodiments are only examples clearly described and not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or variations can be made on the basis of the above description. It is not necessary and impossible to list all the implementation manners here. And the obvious changes or variations derived therefrom are still within the protection scope of the present invention.

Claims

1. A preparation method of an electrochemiluminescent conductive hydrogel, characterized in that, It includes the following steps: S1. Add sucrose and polyvinyl alcohol into water according to the mass ratio of (1 - 2):(3 - 5), heat and stir evenly to obtain mixture A; S2. Dissolve borax, surface - hydroxylated indium tin oxide nanoparticles and tris(2,2’ - bipyridine) ruthenium(II) hexahydrate in water according to the mass ratio of (1 - 2):(1 - 2):(0.03 - 0.05), and heat to form mixture B; S3. Mix mixture A in step S1 and mixture B in step S2 to prepare an electrochemiluminescence conductive hydrogel.

2. The preparation method of the electrochemiluminescent conductive hydrogel according to claim 1, characterized in that, In step S1, the specific process of obtaining mixture A is: First, dissolve sucrose in water to obtain a sucrose solution; then add polyvinyl alcohol to the sucrose solution; then heat to boiling, and then cool down to 90°C - 95°C and stir for 1h - 3h to obtain a translucent viscous mixture A.

3. The preparation method of the electrochemiluminescent conductive hydrogel according to claim 1, characterized in that, In step S2, the heating temperature is 90°C - 95°C.

4. The preparation method of the electrochemiluminescent conductive hydrogel according to claim 1, wherein, In step S2, the surface - hydroxylated indium tin oxide nanoparticles are obtained by suspending indium tin oxide nanoparticles in a potassium hydroxide solution, and then successively performing ultrasonic dispersion, washing, centrifugation and drying.

5. The preparation method of the electrochemiluminescent conductive hydrogel according to claim 4, wherein The mass - to - volume ratio of the indium tin oxide nanoparticles to the potassium hydroxide solution is 1g:50mL, the concentration of the potassium hydroxide solution is 1mol / L; the average particle size of the indium tin oxide nanoparticles is 30nm.

6. An electrochemiluminescence conductive hydrogel prepared by the preparation method of the electrochemiluminescence conductive hydrogel according to claim 1.

7. Application of the electrochemiluminescence conductive hydrogel as claimed in claim 6 as an electrode material in water level early warning / monitoring.

8. A hydrogel electrode device, characterized in that, It includes a cathode, an anode and a gel electrode sheet; the gel electrode sheet is located between the cathode and the anode, and the gel electrode sheet is in contact with the conductive surfaces of the cathode and the anode respectively; both the cathode and the anode are FTO electrodes; the gel electrode sheet is made of the electrochemiluminescence conductive hydrogel according to claim 6.

9. The hydrogel electrode device according to claim 8, wherein Among the cathode and the anode, one is a serrated FTO electrode and the other is a strip - shaped FTO electrode; a gel electrode sheet is arranged on each tooth of the conductive surface of the serrated FTO electrode.

10. Application of the hydrogel electrode device as claimed in claim 8 as a monitoring element in water level early warning / monitoring.

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