Preparation method and application of hydrogen-sensitive particles based on coaxial capillary glass tube microfluidic device
Hydrogen-sensitive particles prepared using a coaxial capillary glass tube microfluidic device solve the miniaturization and rapid movement problems of passive hydrogen sensors, achieving low-cost and safe hydrogen detection with rapid response and obvious color change.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- CHINA JILIANG UNIV
- Filing Date
- 2023-12-21
- Publication Date
- 2026-07-14
Smart Images
Figure CN117732521B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of functional materials technology, specifically to a method for preparing hydrogen-sensitive particles based on a coaxial capillary glass tube microfluidic device and its application. Background Technology
[0002] In recent years, hydrogen energy, as a clean, efficient, and sustainable secondary energy source, has gradually been recognized as an important option for climate-friendly energy solutions. Currently, the hydrogen energy industry cluster is expanding rapidly, and the industry's development is showing explosive potential. However, hydrogen is a gas prone to leakage and is highly flammable and explosive under normal conditions. Therefore, how to efficiently and effectively meet the needs of hydrogen sensors and other detection instruments in the production, storage, transportation, and use stages has become a focus of attention. Commonly used gas sensors can be divided into two main categories: active and passive. Active sensors include resistive semiconductor sensors and thermoelectric sensors, whose principle is mainly based on detecting changes in sensor resistance or other electrical signals to confirm whether a gas leak has occurred. These devices typically require an external power supply and generate heat or even induce electrical sparks during operation, thus posing certain safety hazards. Existing hydrogen sensors are mostly active sensors, with complex manufacturing methods and high production costs, limiting their application in the field of hydrogen sensors. In contrast, existing passive sensors, such as fiber optic sensors, while eliminating the potential dangers of external power supplies, still require various auxiliary observation instruments and are relatively large and have limited mobility. Summary of the Invention
[0003] The purpose of this invention is to solve the problem that existing passive hydrogen sensors cannot meet the requirements of complex and specific scenarios such as miniaturization and rapid movement, and to provide a method for preparing hydrogen-sensitive particles based on a coaxial capillary glass tube microfluidic device and its application.
[0004] The coaxial capillary glass tube microfluidic device consists of an injection pump a1, an injection pump b2, an injection pump c3, a square glass tube 6, a capillary glass tube a7, a capillary glass tube b9, an ultraviolet light source 15, and a collection device 16.
[0005] Both capillary glass tubes a7 and b9 have a tapered end. The diameter of the tapered end of capillary glass tube a7 is 20μm to 70μm, and the diameter of the tapered end of capillary glass tube b9 is 250μm to 350μm. The tapered end of capillary glass tube a7 extends from the left end of square glass tube 6, and the tapered end of capillary glass tube b9 extends from the right end of square glass tube 6. The center lines of capillary glass tube a7 and capillary glass tube b9 coincide, and the distance between the tapered ends of capillary glass tube a7 and capillary glass tube b9 is 75 to 150μm.
[0006] The circular opening at the other end of the capillary glass tube a7 serves as the inner phase solution inlet 4, the annular inlet formed between the outer wall of the capillary glass tube a7 and the inner wall of the square glass tube 6 serves as the intermediate phase solution inlet 5, the annular inlet formed between the outer wall of the capillary glass tube b9 and the inner wall of the square glass tube 6 serves as the outer phase solution inlet 12, and the circular opening at the other end of the capillary glass tube b9 serves as the light curing channel outlet 10.
[0007] The outlet of the injection pump a1 is connected to the inlet 5 of the intermediate phase solution via a pipeline; the outlet of the injection pump b2 is connected to the inlet 4 of the inner phase solution via a pipeline; and the outlet of the injection pump c3 is connected to the inlet 12 of the outer phase solution via a pipeline. The tail end of the capillary glass tube b9 is a light curing channel 14. An ultraviolet light source 15 is provided 5-10 cm above the light curing channel 14, which can provide a circular light curing area with a diameter of 1-4 cm. A collection device 16 is provided below the outlet 10 of the light curing channel.
[0008] The preparation method of hydrogen-sensitive particles based on a coaxial capillary glass tube microfluidic device is carried out according to the following steps:
[0009] Step 1: First, start syringe pump a1 to inject the mesophase solution into the mesophase solution inlet 5, start syringe pump b2 to inject the internal phase solution into the internal phase solution inlet 4, and start syringe pump c3 to inject the external phase solution into the external phase solution inlet 12; then, adjust the flow rate of the oil phase solution to 1-5 mL / h at 15-30℃, and then adjust the flow rates of both the mesophase solution and the internal phase solution to 0.5-2 mL / h.
[0010] The intermediate phase solution is a hydrogel solution containing palladium; the inner phase solution is a hydrogel solution containing tungsten; and the outer phase solution is an oil phase solution.
[0011] Step 2: After the oil-water interface in the solution mixing shear zone 8 stabilizes, adjust the flow rate of the oil phase solution to 10-20 mL / h, and at the same time adjust the flow rates of the intermediate phase solution and the inner phase solution to 1-3 mL / h, until the double emulsion droplets 11 are stably generated in the capillary glass tube b9. The core of the double emulsion droplet 11 is a hydrogel solution containing tungsten, and the outer shell is a hydrogel solution containing palladium.
[0012] Step 3: After the double emulsion droplets 11 flow into the photocuring channel 14, turn on the ultraviolet light source 15 to perform photocuring treatment on the double emulsion droplets 11 to obtain hydrogel particles 13 with a double-layer structure, which are collected by the collection device 16; after rinsing, the hydrogel particles 13 are added to a reducing aqueous solution for reduction treatment, then added to an acidic solution for acidification treatment, and finally heated in a water bath at 70-85°C for 1-2 hours, rinsed, and hydrogen-sensitive particles are obtained.
[0013] The application of the hydrogen-sensitive particles in the preparation of hydrogen-sensitive sensors involves the following steps: During hydrogen leak detection, when the hydrogen-sensitive particles come into contact with leaked hydrogen, the hydrogen molecules are dissociated into hydrogen ions after contacting palladium ions on the surface of the hydrogen-sensitive sensor. The dissociated hydrogen ions further diffuse into the inner tungsten trioxide lattice. The tungsten ions exhibit different colors due to changes in their valence state. Finally, based on the color change of the hydrogen-sensitive particles, hydrogen leak detection is completed.
[0014] The beneficial effects of this invention are:
[0015] (1) This invention relates to a method for preparing hydrogen-sensitive particles based on a coaxial capillary glass tube microfluidic device. The method produces hydrogen-sensitive particles, and the microfluidic device can generate uniformly sized droplets, enabling large-scale production in a short time. This achieves rapid manufacturing of hydrogel-sensitive materials with a bilayer structure, gentle cross-linking, simple subsequent processing, and significant changes. It has broad application prospects in hydrogen transportation and storage, leak monitoring, and other fields.
[0016] (2) The hydrogen-sensitive particles prepared by the present invention have excellent catalytic properties due to the modification of the outer shell with palladium particles; palladium itself is easy to combine with hydrogen and has a certain selectivity for hydrogen; the inner tungsten layer is also of great use in the field of sensors due to its low price and easy availability.
[0017] (3) The present invention can adjust the liquid flow rate according to the usage environment, thereby controlling the particle size, and can generate uniform particles of different sizes. It is convenient and quick, suitable for different occasions, and does not require an external power source, effectively reducing safety hazards.
[0018] (4) The present invention can change color in a hydrogen atmosphere with a concentration below the hydrogen explosion limit. The change is obvious, can be observed with the naked eye, and is fast. It is sensitive to hydrogen.
[0019] This invention provides a method for preparing hydrogen-sensitive particles based on a coaxial capillary glass tube microfluidic device and its application. Attached Figure Description
[0020] Figure 1 This is a schematic diagram of a microfluidic device based on a coaxial capillary glass tube according to the present invention. 1 represents injection pump a, 2 represents injection pump b, 3 represents injection pump c, 4 represents the inner phase solution inlet, 5 represents the intermediate phase solution inlet, 6 represents the square glass tube, 7 represents the capillary glass tube a, 8 represents the solution mixing and shearing zone, 9 represents the capillary glass tube b, 10 represents the photocuring channel outlet, 11 represents the dual emulsion droplet, 12 represents the outer phase solution inlet, 13 represents the hydrogel particle, 14 represents the photocuring channel, 15 represents the ultraviolet light source, and 16 represents the collection device.
[0021] Figure 2 for Figure 1A schematic diagram of the assembly of capillary glass tubes a and b with a square glass tube. 4 represents the inlet of the inner phase solution, 5 represents the inlet of the intermediate phase solution, 6 represents the square glass tube, 7 represents capillary glass tube a, 9 represents capillary glass tube b, 11 represents the double emulsion droplet, and 12 represents the inlet of the outer phase solution.
[0022] Figure 3 The image shows the hydrogen-sensitive particles before hydrogen gas is introduced; 17 represents the hydrogen-sensitive particles before hydrogen gas is introduced.
[0023] Figure 4 The image shows the hydrogen-sensitive particles after hydrogen gas is introduced; 18 represents the hydrogen-sensitive particles after hydrogen gas is introduced.
[0024] Figure 5 Optical image of hydrogel particles with a bilayer structure, 19 represents the external phase solution, and 13 represents the hydrogel particles. Detailed Implementation
[0025] Specific implementation method one: The coaxial capillary glass tube microfluidic device in this implementation method consists of an injection pump a1, an injection pump b2, an injection pump c3, a square glass tube 6, a capillary glass tube a7, a capillary glass tube b9, an ultraviolet light source 15, and a collection device 16.
[0026] Both capillary glass tubes a7 and b9 have a tapered end. The diameter of the tapered end of capillary glass tube a7 is 20μm to 70μm, and the diameter of the tapered end of capillary glass tube b9 is 250μm to 350μm. The tapered end of capillary glass tube a7 extends from the left end of square glass tube 6, and the tapered end of capillary glass tube b9 extends from the right end of square glass tube 6. The center lines of capillary glass tube a7 and capillary glass tube b9 coincide, and the distance between the tapered ends of capillary glass tube a7 and capillary glass tube b9 is 75 to 150μm.
[0027] The circular opening at the other end of the capillary glass tube a7 serves as the inner phase solution inlet 4, the annular inlet formed between the outer wall of the capillary glass tube a7 and the inner wall of the square glass tube 6 serves as the intermediate phase solution inlet 5, the annular inlet formed between the outer wall of the capillary glass tube b9 and the inner wall of the square glass tube 6 serves as the outer phase solution inlet 12, and the circular opening at the other end of the capillary glass tube b9 serves as the light curing channel outlet 10.
[0028] The outlet of the injection pump a1 is connected to the inlet 5 of the intermediate phase solution via a pipeline; the outlet of the injection pump b2 is connected to the inlet 4 of the inner phase solution via a pipeline; and the outlet of the injection pump c3 is connected to the inlet 12 of the outer phase solution via a pipeline. The tail end of the capillary glass tube b9 is a light curing channel 14. An ultraviolet light source 15 is installed 5-10 cm above the light curing channel 14, and a collection device 16 is installed below the outlet 10 of the light curing channel.
[0029] Specific Implementation Method Two: This implementation method is based on the preparation method of hydrogen-sensitive particles using a coaxial capillary glass tube microfluidic device, and is carried out according to the following steps:
[0030] Step 1: First, start syringe pump a1 to inject the mesophase solution into the mesophase solution inlet 5, start syringe pump b2 to inject the internal phase solution into the internal phase solution inlet 4, and start syringe pump c3 to inject the external phase solution into the external phase solution inlet 12; then, adjust the flow rate of the oil phase solution to 1-5 mL / h at 15-30℃, and then adjust the flow rates of both the mesophase solution and the internal phase solution to 0.5-2 mL / h.
[0031] The intermediate phase solution is a hydrogel solution containing palladium; the inner phase solution is a hydrogel solution containing tungsten; and the outer phase solution is an oil phase solution.
[0032] Step 2: After the oil-water interface in the solution mixing shear zone 8 stabilizes, adjust the flow rate of the oil phase solution to 10-20 mL / h, and at the same time adjust the flow rates of the intermediate phase solution and the inner phase solution to 1-3 mL / h, until the double emulsion droplets 11 are stably generated in the capillary glass tube b9. The core of the double emulsion droplet 11 is a hydrogel solution containing tungsten, and the outer shell is a hydrogel solution containing palladium.
[0033] Step 3: After the double emulsion droplets 11 flow into the photocuring channel 14, turn on the ultraviolet light source 15 to perform photocuring treatment on the double emulsion droplets 11 to obtain hydrogel particles 13 with a double-layer structure, which are collected by the collection device 16; after rinsing, the hydrogel particles 13 are added to a reducing aqueous solution for reduction treatment, then added to an acidic solution for acidification treatment, and finally heated in a water bath at 70-85°C for 1-2 hours, rinsed, and hydrogen-sensitive particles are obtained.
[0034] Specific Implementation Method 3: The difference between this implementation method and Specific Implementation Method 1 or 2 is that the capillary glass tube b9 is hydrophobically treated, and the materials used for hydrophobic treatment include, but are not limited to, octadecyltrichlorosilane, perfluorooctyltrichlorosilane, or zinc oxide.
[0035] The other steps are the same as in Specific Implementation Method 1 or 2.
[0036] Specific Implementation Method Four: The difference between this implementation method and Specific Implementation Methods One to Three is that the palladium-containing hydrogel solution is composed of a palladium-containing solution and a hydrogel precursor. The palladium-containing solution includes, but is not limited to, sodium tetrachloropalladium or palladium chloride acetate, and the hydrogel precursor includes, but is not limited to, polyethylene glycol diacrylate or acrylic acid.
[0037] The other steps are the same as those in Specific Implementation Methods One to Three.
[0038] Specific Implementation Method 5: The difference between this implementation method and Specific Implementation Methods 1 to 4 is that the tungsten-containing hydrogel solution is composed of a tungsten-containing solution and a hydrogel precursor. The tungsten-containing solution includes, but is not limited to, nano-tungsten trioxide dispersion, tungsten chloride or ammonium metatungstate, and the hydrogel precursor includes, but is not limited to, polyethylene glycol diacrylate or acrylic acid.
[0039] The other steps are the same as those in Specific Implementation Methods One through Four.
[0040] Specific Implementation Method Six: The difference between this implementation method and Specific Implementation Methods One to Five is that the oil phase solution mentioned includes, but is not limited to, mineral oil, silicone oil, or fluorinated oil.
[0041] The other steps are the same as those in Specific Implementation Methods 1 to 5.
[0042] Specific Implementation Method Seven: The difference between this implementation method and Specific Implementation Methods One to Six is that the material used for the light curing channel 14 includes, but is not limited to, polytetrafluoroethylene or polyethylene.
[0043] The other steps are the same as those in Specific Implementation Methods 1 to 6.
[0044] Specific Implementation Method Eight: The difference between this implementation method and one of the specific implementation methods one to seven is that the reducing aqueous solution mentioned in step 3 includes, but is not limited to, polyvinylpyrrolidone, potassium bromide, ascorbic acid or sodium citrate.
[0045] The other steps are the same as those in Specific Implementation Methods 1 to 7.
[0046] Specific Implementation Method Nine: The difference between this implementation method and Specific Implementation Methods One to Eight is that the acidic solution mentioned in step 3 includes, but is not limited to, hydrochloric acid solution or hydrobromic acid solution.
[0047] The other steps are the same as those in Specific Implementation Methods 1 to 8.
[0048] Specific Implementation Method 10: The application of the hydrogen-sensitive particles described in this implementation method in the preparation of hydrogen-sensitive sensors is as follows: During the hydrogen leak detection process, when the hydrogen-sensitive particles come into contact with leaked hydrogen, the hydrogen molecules are dissociated into hydrogen ions after contacting the palladium ions on the surface of the hydrogen-sensitive sensor. The dissociated hydrogen ions further diffuse into the inner tungsten trioxide lattice. The tungsten ions exhibit different colors due to the change in valence state. Finally, the hydrogen leak detection is completed based on the color change of the hydrogen-sensitive particles.
[0049] The beneficial effects of the present invention are verified using the following embodiments:
[0050] Example 1: A coaxial capillary glass tube microfluidic device, consisting of an injection pump a1, an injection pump b2, an injection pump c3, a square glass tube 6, a capillary glass tube a7, a capillary glass tube b9, an ultraviolet light source 15, and a collection device 16.
[0051] Both capillary glass tubes a7 and b9 have a tapered end. The diameter of the tapered end of capillary glass tube a7 is 50 μm, and the diameter of the tapered end of capillary glass tube b9 is 300 μm. The tapered end of capillary glass tube a7 extends from the left end of square glass tube 6, and the tapered end of capillary glass tube b9 extends from the right end of square glass tube 6. The center lines of capillary glass tube a7 and capillary glass tube b9 coincide, and the distance between the tapered ends of capillary glass tube a7 and capillary glass tube b9 is 120 μm.
[0052] The circular opening at the other end of the capillary glass tube a7 serves as the inner phase solution inlet 4, the annular inlet formed between the outer wall of the capillary glass tube a7 and the inner wall of the square glass tube 6 serves as the intermediate phase solution inlet 5, the annular inlet formed between the outer wall of the capillary glass tube b9 and the inner wall of the square glass tube 6 serves as the outer phase solution inlet 12, and the circular opening at the other end of the capillary glass tube b9 serves as the light curing channel outlet 10.
[0053] The outlet of the injection pump a1 is connected to the inlet 5 of the intermediate phase solution via a pipeline; the outlet of the injection pump b2 is connected to the inlet 4 of the inner phase solution via a pipeline; and the outlet of the injection pump c3 is connected to the inlet 12 of the outer phase solution via a pipeline. The tail of the capillary glass tube b9 is a light curing channel 14. An ultraviolet light source 15 is installed 7 cm above the light curing channel 14, and a collection device 16 is installed below the outlet 10 of the light curing channel.
[0054] Example 2: A method for preparing hydrogen-sensitive particles based on a coaxial capillary glass tube microfluidic device, comprising the following steps:
[0055] Step 1: First, start syringe pump a1 to inject the mesophase solution into the mesophase solution inlet 5, start syringe pump b2 to inject the internal phase solution into the internal phase solution inlet 4, and start syringe pump c3 to inject the external phase solution into the external phase solution inlet 12; then, at 25°C, adjust the flow rate of the oil phase solution to 5 mL / h, and then adjust the flow rates of both the mesophase solution and the internal phase solution to 1.5 mL / h.
[0056] The intermediate phase solution is a hydrogel solution containing palladium; the inner phase solution is a hydrogel solution containing tungsten; and the outer phase solution is an oil phase solution.
[0057] Step 2: After the oil-water interface in the solution mixing shear zone 8 stabilizes, the flow rate of the oil phase solution is adjusted to 15 mL / h, and the flow rates of the intermediate phase solution and the inner phase solution are both adjusted to 2 mL / h, until the double emulsion droplets 11 are stably generated in the capillary glass tube b9. The core of the double emulsion droplet 11 is a hydrogel solution containing tungsten, and the outer shell is a hydrogel solution containing palladium.
[0058] Step 3: After the double emulsion droplets 11 flow into the photocuring channel 14, turn on the ultraviolet light source 15 to perform photocuring treatment on the double emulsion droplets 11 to obtain hydrogel particles 13 with a double-layer structure, which are collected by the collection device 16; after rinsing, the hydrogel particles 13 are added to a reducing aqueous solution for reduction treatment, then added to an acidic solution for acidification treatment, and finally heated in a water bath at 80°C for 2 hours, and rinsed to obtain hydrogen-sensitive particles.
[0059] The capillary glass tube b9 is hydrophobically treated, and the materials used for the hydrophobic treatment include, but are not limited to, octadecyltrichlorosilane, perfluorooctyltrichlorosilane, or zinc oxide.
[0060] The palladium-containing hydrogel solution comprises a palladium-containing solution and a hydrogel precursor. The palladium-containing solution includes, but is not limited to, sodium tetrachloropalladium or palladium chloride / palladium acetate, and the hydrogel precursor includes, but is not limited to, polyethylene glycol diacrylate or acrylic acid. The palladium-containing hydrogel solution serves to impart a catalytic layer and gas selectivity to the sensor.
[0061] The tungsten-containing hydrogel solution comprises a tungsten-containing solution and a hydrogel precursor. The tungsten-containing solution includes, but is not limited to, nano-tungsten trioxide dispersion, tungsten chloride, or ammonium metatungstate. The hydrogel precursor includes, but is not limited to, polyethylene glycol diacrylate or acrylic acid. The tungsten-containing hydrogel solution serves to impart a sensitive layer to the sensor, enabling it to respond to changes in the gas atmosphere.
[0062] The oil phase solution includes, but is not limited to, mineral oil, silicone oil, or fluorinated oil. The role of the oil phase solution is to provide shear force in the solution mixing shear zone 8, aiding in the formation of the double emulsion droplets.
[0063] The materials used in the photocuring channel 14 include, but are not limited to, polytetrafluoroethylene or polyethylene, and serve to provide a site for the curing and formation of the double emulsion droplets 11.
[0064] The ultraviolet light source 15 can chemically crosslink the photosensitive material hydrogel, thereby obtaining hydrogel particles 13.
[0065] The reducing aqueous solution includes, but is not limited to, polyvinylpyrrolidone, potassium bromide, ascorbic acid, or sodium citrate. The reduction treatment causes a reduction reaction in the hydrogel catalyst layer, enhancing its hydrogen adsorption performance and allowing the gas to penetrate more rapidly and contact the sensitive layer.
[0066] The acidic solution includes, but is not limited to, hydrochloric acid solution or hydrobromic acid solution. Acidification treatment can cause a chemical change in the hydrogel sensitive layer, giving it the ability to change color in a hydrogen atmosphere.
[0067] The hydrogel particles 13 with a bilayer structure are prepared by forming uniformly sized droplets from two immiscible solutions under the action of flow field shear force using microfluidic chip technology, followed by photocuring.
[0068] The application of the hydrogen-sensitive particles in the preparation of hydrogen-sensitive sensors involves the following steps: During hydrogen leak detection, when the hydrogen-sensitive particles come into contact with leaked hydrogen, the hydrogen molecules are dissociated into hydrogen ions after contacting palladium ions on the surface of the hydrogen-sensitive sensor. The dissociated hydrogen ions further diffuse into the inner tungsten trioxide lattice. Due to the change in valence state, the tungsten ions exhibit different colors. Ultimately, the hydrogen-sensitive particles change from pale yellow to a deeper blue, thus completing the sensing process.
[0069] The working process of this embodiment:
[0070] The preparation process in this embodiment utilizes capillary glass tube microfluidic chip technology. A syringe pump feeds solution into different channels of the microfluidic device. When the solution undergoes shearing, it forms uniformly sized double emulsion droplets 11. These droplets 11 solidify upon irradiation with an ultraviolet (UV) light source and eventually flow out of the channel and converge in a collection tray. The collected particles are first placed in a reducing solution for heating and reduction treatment. After a period of time, they are removed, the surface reducing solution is removed, and then they are placed in an acidic solution for heating and acidification treatment. After a period of time, the surface acidified solution is removed, thus preparing the hydrogen-sensitive particles.
[0071] Figure 1 This is a schematic diagram of a microfluidic device based on a coaxial capillary glass tube according to the present invention. Figure 2 for Figure 1 A schematic diagram showing the assembly of capillary glass tubes a and b with a square glass tube; as shown. Figure 1-2As shown, syringes containing three pre-prepared precursor solutions are first fixed to syringe pumps a1, b2, and c3, respectively. The solutions are fed at a uniform rate by adjusting the syringe pump parameters. Adjusting these parameters can be used to prepare sensors with different core-shell thickness ratios and diameters. The inner phase solution is injected through inner phase solution inlet 4, the intermediate phase solution through intermediate phase solution inlet 5, and the outer phase solution through outer phase solution inlet 12. The three solutions meet in the solution mixing shear zone 8. Under the shear force of the outer phase solution, the inner and intermediate phase solutions are sheared into uniformly sized double emulsion droplets. Enclosed by the outer phase solution, the double emulsion droplets 11 enter the collection channel and flow towards the photocuring channel 14. Under the irradiation of the ultraviolet light source 15, the double emulsion droplets 11 undergo cross-linking and solidification into hydrogel particles 13 with a bilayer structure. Finally, they flow through the photocuring channel 14 and are collected in the collection tray.
[0072] Figure 3 The image shows the hydrogen-sensitive particles before hydrogen gas is introduced; 17 indicates the hydrogen-sensitive particles before hydrogen gas is introduced. Figure 4 This is an image of the hydrogen-sensitive particles after hydrogen gas is introduced; 18 represents the hydrogen-sensitive particles after hydrogen gas is introduced. Figure 3 The image shown is of the hydrogen-sensitive particles before hydrogen gas is introduced; no color change occurs. Figure 4 As shown, the hydrogen-sensitive particles exhibit a noticeable color change after hydrogen gas is introduced. The pale yellow, transparent particles gradually turn blue upon contact with hydrogen gas, a phenomenon that is quite evident. The mechanism involves several stages: First, when exposed to hydrogen gas, hydrogen molecules contact the palladium on the sensor surface and dissociate into hydrogen ions and free electrons; this process is called the spillover effect. Subsequently, the dissociated protons and electrons diffuse further into the tungsten trioxide lattice and occupy available sites, ultimately forming tungsten hydrogen bronze. The reaction equation is as follows:
[0073] H2→2H + +2e - ;
[0074] 2H + +2e - +WO3→H x WO3;
[0075] At this point, the valence state of tungsten ions changes. Tungsten ions in tungsten trioxide have a +6 valence, while tungsten ions in tungsten bronze have a mixture of +5 and +6 valence. Tungsten ions will exhibit different colors due to changes in valence state. Therefore, when it comes into contact with hydrogen gas, the sensitive layer of the sensor undergoes a valence state change, turning it from pale yellow to a deeper blue. Thus, a hydrogen leak can be determined based on the color change.
[0076] Figure 5 Optical images of hydrogel particles with a bilayer structure; such as Figure 5As shown, the blank area 19 in the image is the external phase solution, and the hydrogel particles 13 in the image, which clearly have a bilayer structure, are the particles that have been solidified in the collection tray.
Claims
1. A method for preparing hydrogen-sensitive particles based on a coaxial capillary glass tube microfluidic device, characterized in that... The preparation method is carried out according to the following steps: Step 1: First, start the injection pump a (1) to inject the intermediate phase solution into the intermediate phase solution inlet (5), start the injection pump b (2) to inject the internal phase solution into the internal phase solution inlet (4), and start the injection pump c (3) to inject the external phase solution into the external phase solution inlet (12); Then, at 15~30℃, the flow rate of the external phase solution was adjusted to 1~5 mL / h, and the flow rates of both the intermediate phase solution and the internal phase solution were adjusted to 0.5~2 mL / h. The intermediate phase solution is a hydrogel solution containing palladium; the inner phase solution is a hydrogel solution containing tungsten; and the outer phase solution is an oil phase solution. Step 2: After the oil-water interface in the solution mixing shear zone (8) stabilizes, adjust the flow rate of the oil phase solution to 10~20mL / h, and at the same time adjust the flow rates of the intermediate phase solution and the inner phase solution to 1~3mL / h, until the double emulsion droplet (11) is stably generated in the capillary glass tube b (9). The core of the double emulsion droplet (11) is a hydrogel solution containing tungsten, and the outer shell is a hydrogel solution containing palladium. Step 3: After the double emulsion droplets (11) flow into the photocuring channel (14), turn on the ultraviolet light source (15) to perform photocuring treatment on the double emulsion droplets (11) to obtain hydrogel particles (13) with a double-layer structure, which are collected by the collection device (16); after rinsing, the hydrogel particles (13) are added to a reducing aqueous solution for reduction treatment, then added to an acidic solution for acidification treatment, and finally heated in a water bath at 70~85℃ for 1~2h, rinsed, and hydrogen-sensitive particles are obtained; The coaxial capillary glass tube microfluidic device consists of an injection pump a (1), an injection pump b (2), an injection pump c (3), a square glass tube (6), a capillary glass tube a (7), a capillary glass tube b (9), an ultraviolet light source (15), and a collection device (16). Both capillary glass tubes a (7) and b (9) have a tapered structure at one end. The diameter of the tapered end of capillary glass tube a (7) is 20 μm to 70 μm, and the diameter of the tapered end of capillary glass tube b (9) is 250 μm to 350 μm. The tapered end of capillary glass tube a (7) extends from the left end of the square glass tube (6), and the tapered end of capillary glass tube b (9) extends from the right end of the square glass tube (6). The center lines of capillary glass tube a (7) and capillary glass tube b (9) coincide, and the distance between the tapered end of capillary glass tube a (7) and the tapered end of capillary glass tube b (9) is 75 to 150 μm. The circular opening at the other end of the capillary glass tube a (7) serves as the inlet (4) of the inner phase solution. The annular inlet formed between the outer wall of the capillary glass tube a (7) and the inner wall of the square glass tube (6) serves as the inlet (5) of the intermediate phase solution. The annular inlet formed between the outer wall of the capillary glass tube b (9) and the inner wall of the square glass tube (6) serves as the inlet (12) of the outer phase solution. The circular opening at the other end of the capillary glass tube b (9) serves as the outlet (10) of the photocuring channel. The outlet of the injection pump a (1) is connected to the inlet of the intermediate phase solution (5) through a pipeline, the outlet of the injection pump b (2) is connected to the inlet of the inner phase solution (4) through a pipeline, and the outlet of the injection pump c (3) is connected to the inlet of the outer phase solution (12) through a pipeline; the tail of the capillary glass tube b (9) is a light curing channel (14), an ultraviolet light source (15) is provided 5-10 cm above the light curing channel (14), and a collection device (16) is provided below the outlet (10) of the light curing channel.
2. The method for preparing hydrogen-sensitive particles based on a coaxial capillary glass tube microfluidic device according to claim 1, characterized in that... The capillary glass tube b (9) is hydrophobically treated, and the materials used for hydrophobic treatment are octadecyltrichlorosilane, perfluorooctyltrichlorosilane or zinc oxide.
3. The method for preparing hydrogen-sensitive particles based on a coaxial capillary glass tube microfluidic device according to claim 1, characterized in that... The palladium-containing hydrogel solution is composed of a palladium-containing solution and a hydrogel precursor. The palladium-containing solution is sodium tetrachloropalladium, palladium chloride, or palladium acetate, and the hydrogel precursor is polyethylene glycol diacrylate or acrylic acid.
4. The method for preparing hydrogen-sensitive particles based on a coaxial capillary glass tube microfluidic device according to claim 1, characterized in that... The tungsten-containing hydrogel solution is composed of a tungsten-containing solution and a hydrogel precursor. The tungsten-containing solution is a nano-tungsten trioxide dispersion, tungsten chloride, or ammonium metatungstate, and the hydrogel precursor is polyethylene glycol diacrylate or acrylic acid.
5. The method for preparing hydrogen-sensitive particles based on a coaxial capillary glass tube microfluidic device according to claim 1, characterized in that... The oil phase solution is mineral oil, silicone oil, or fluorinated oil.
6. The method for preparing hydrogen-sensitive particles based on a coaxial capillary glass tube microfluidic device according to claim 1, characterized in that... The material used for the photocurable channel (14) is polytetrafluoroethylene or polyethylene.
7. The method for preparing hydrogen-sensitive particles based on a coaxial capillary glass tube microfluidic device according to claim 1, characterized in that... The reducing aqueous solution mentioned in step 3 is polyvinylpyrrolidone, potassium bromide, ascorbic acid, or sodium citrate.
8. The method for preparing hydrogen-sensitive particles based on a coaxial capillary glass tube microfluidic device according to claim 1, characterized in that... The acidic solution mentioned in step 3 is a hydrochloric acid solution or a hydrobromic acid solution.
9. The application of the hydrogen-sensitive particles prepared by the method according to any one of claims 1-8, characterized in that... The application of the hydrogen-sensitive particles in the preparation of hydrogen-sensitive sensors involves the following steps: During hydrogen leak detection, when the hydrogen-sensitive particles come into contact with leaked hydrogen, the hydrogen molecules are dissociated into hydrogen ions after contacting palladium ions on the surface of the hydrogen-sensitive sensor. The dissociated hydrogen ions further diffuse into the inner tungsten trioxide lattice. The tungsten ions exhibit different colors due to changes in their valence state. Finally, based on the color change of the hydrogen-sensitive particles, the hydrogen leak detection is completed.