Flexible ammonia gas sensor for nephropathy monitoring and preparation method thereof
The preparation of flexible ammonia sensors through the conductive polymer composite co-doped MXene and ionic liquids solves the problem of difficulty in taking into account both sensitivity and cost in the prior art, and achieves high sensitivity and low detection limit nephropathy monitoring, which is suitable for large-scale production and wireless real-time monitoring.
Patent Information
- Application Number
- CN202510291099.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-12
- Publication Date
- 2025-07-04
AI Technical Summary
Existing flexible ammonia sensors are difficult to have high sensitivity, low detection limit and low cost, and traditional methods for diagnosing renal diseases are highly invasive and time-consuming, making it difficult to achieve early screening and home monitoring.
A conductive polymer composite material co-doped with MXene and ionic liquid is used as the sensing layer, combined with an interdigital electrode and a flexible substrate, and a flexible ammonia sensor is prepared by in-situ polymerization. The catalytic action of MXene and the electrostatic cross-linking action of ionic liquid are used to enhance the sensitivity and response speed of the sensor.
It realizes an ammonia sensor with high sensitivity, low detection limit and low cost. It can monitor the ammonia concentration exhaled by nephropathy patients in real time at room temperature, which is suitable for large-scale production and wireless monitoring.
Smart Images
Figure CN120253975A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical fields of sensing materials and flexible electronic devices, and particularly relates to a flexible ammonia sensor for kidney disease monitoring and a preparation method thereof. Background Art
[0002] Ammonia is a metabolite of the human body. When the renal function of the human body is damaged, the excretion of end metabolites (such as urea) can be delayed, resulting in the accumulation of excessive ammonia. Patients with kidney diseases can usually detect a relatively high level of ammonia in their breath. Therefore, ammonia can be used as a breath signature for the early screening or indirect diagnosis of kidney diseases.
[0003] Traditional methods for diagnosing kidney diseases include blood measurement, urine test, renal biopsy, B-ultrasound, computed tomography or magnetic resonance imaging. These methods are usually invasive, with low comfort, time-consuming and costly, only applicable to a limited range of patients, and require testers to have relatively high professional detection techniques, making it difficult to promote and apply. Some patients are usually unaware of the development of the disease until the late stage of renal failure and cannot obtain timely and rapid diagnosis. Ammonia sensors have the advantages of small size, simple operation, rapid response, etc., providing a convenient, low-cost and non-destructive method for the early screening and indirect diagnosis of kidney diseases. At the same time, home monitoring can also be achieved. Existing technologies show that the ammonia concentration exhaled by healthy people is between 200 - 500 ppb, while the ammonia concentration in the exhaled gas of patients with renal failure before dialysis is about 2000 ppb. Only ammonia sensors with high sensitivity have the ability to evaluate the possible renal failure of patients. Therefore, it is of great practical significance to develop an ammonia sensor with low cost, low detection limit and high sensitivity.
[0004] Conductive polymers have been widely used in the field of ammonia sensing due to their strong mechanical flexibility, easy batch processing, suitability for working at room temperature, adjustable sensing performance, and convenience for system integration. However, it is difficult to obtain an ammonia sensor with excellent sensitivity, low detection limit and low cost using a single conductive polymer material. To overcome the above deficiencies, many researchers have tried to compound conductive polymers with carbon nanomaterials, nano-metals or metal oxides, change the preparation method or combination mode of the materials. Although flexible ammonia sensors with high sensitivity have been obtained, the preparation difficulty and cost of the sensors have been greatly increased, making it difficult to meet the requirements of industrial mass production and low energy consumption. Therefore, it is urgent to explore new sensing materials and preparation methods to meet the application requirements of more fields. Summary of the Invention
[0005] To address the deficiencies of the above prior art, the present invention provides a flexible ammonia sensor for nephropathy monitoring and a preparation method thereof. The flexible ammonia sensor has the advantages of high sensitivity, low detection limit (ppb level), simple preparation process, and low cost, and can realize real-time monitoring of the ammonia concentration exhaled by nephropathy patients.
[0006] To achieve the above object, the specific technical solutions of the present invention are as follows:
[0007] In the first aspect, the present invention provides a flexible ammonia sensor for nephropathy monitoring, including: a flexible substrate, interdigital electrodes, and a sensing layer; the interdigital electrodes are located on the surface of the flexible substrate, and the sensing layer covers the interdigital electrodes;
[0008] Among them, the sensing layer includes a conductive polymer composite material co-doped with MXene and an ionic liquid.
[0009] Aiming at the problem that flexible ammonia sensors in the prior art are difficult to have both high sensitivity, low detection limit, and low cost, the present invention uses a conductive polymer composite material co-doped with MXene and an ionic liquid as the sensing layer. This composite material has a three-dimensional porous honeycomb structure, which can greatly increase the contact area between ammonia and the sensing film, improve the carrier transport speed, and thus improve the sensitivity and response / recovery speed of the sensor; at the same time, the present invention adjusts the doping amounts of MXene and the ionic liquid, and adjusts the preparation method of the conductive polymer composite material co-doped with MXene and the ionic liquid, and utilizes the catalytic effect of MXene, the electrostatic cross-linking effect of the ionic liquid, and the synergistic enhancement effect between MXene, the ionic liquid, and the conductive polymer, so that the conductive polymer composite material co-doped with MXene and the ionic liquid has more excellent sensitivity to low-concentration ammonia at room temperature.
[0010] Preferably, the MXene includes at least one of Ti3C2T x , Nb2CT x , V2CT x .
[0011] Preferably, the ionic liquid includes at least one of 1-vinyl-3-butylimidazolium bromide (VBIMBr), 1-butyl-3-methylimidazolium bromide (BMIMBr), 1-ethyl-3-methylimidazolium tetrafluoroborate, and 1-butyl-3-methylimidazolium tetrafluoroborate.
[0012] Preferably, the conductive polymer includes at least one of poly(3,4-ethylenedioxythiophene):polystyrene sulfonate, polyaniline:polystyrene sulfonate, and polypyrrole:polystyrene sulfonate.
[0013] Preferably, the thickness of the sensing layer is 100~500 nm.
[0014] Preferably, the thickness of the interdigital electrode is 1-100 μm, the finger width is 10-1000 μm, and the spacing between fingers is 10-1000 μm.
[0015] Preferably, the flexible substrate includes an organic sheet or fiber; wherein, the organic sheet includes polyethylene terephthalate (PET), polyimide, polyvinylidene fluoride, polymethyl methacrylate or polycarbonate; the fiber includes cotton, polypropylene, polyester or nylon.
[0016] Preferably, the interdigital electrode is prepared from a conductive material, and the conductive material includes at least one of conductive silver paste, graphene, carbon nanotubes, and noble metal materials.
[0017] In a second aspect, the present invention provides a method for preparing the flexible ammonia sensor, including the following steps:
[0018] Prepare an interdigital electrode on the surface of the flexible substrate; prepare a conductive polymer composite solution co-doped with MXene and ionic liquid by in-situ polymerization;
[0019] Mix the conductive polymer composite solution co-doped with MXene and ionic liquid with a surfactant uniformly to obtain a mixed solution, coat the mixed solution on the surface of the flexible substrate with an interdigital electrode, and dry to obtain the flexible ammonia sensor.
[0020] Preferably, the conductive polymer composite solution co-doped with MXene and ionic liquid is prepared by the following method:
[0021] (1) Add a polymer monomer, an oxidant and polystyrene sulfonate to the MXene dispersion to obtain a mixed reaction solution, and carry out an in-situ polymerization reaction on the mixed reaction solution at room temperature to obtain a mixed solution;
[0022] (2) Dialyze the mixed solution in water to obtain a conductive polymer composite solution doped with MXene;
[0023] (3) Stir and mix the conductive polymer composite solution doped with MXene and the ionic liquid at room temperature for 1-4 h to cause electrostatic self-assembly to obtain a conductive polymer composite solution co-doped with MXene and ionic liquid.
[0024] Preferably, the concentration of the MXene dispersion is 0.25-1 mg / mL; the concentration (v / v) of the polymer monomer in the mixed reaction solution is 0.5-25 μL / mL; the concentration (v / v) of the polystyrene sulfonate in the mixed reaction solution is 0.5-25 μL / mL; the concentration of the oxidant in the mixed reaction solution is 5-50 mg / mL.
[0025] Preferably, in the conductive polymer composite solution co-doped with MXene and ionic liquid, the concentration of the ionic liquid is 20 - 80 mg / mL.
[0026] Preferably, the polymer monomer includes at least one of 3,4-ethylenedioxythiophene, aniline, and pyrrole.
[0027] Preferably, the oxidant includes at least one of ammonium persulfate, iron chloride, and iron sulfate.
[0028] Preferably, the dialysis time is 4 - 8 h.
[0029] Preferably, the surfactant includes Zonyl FS-300 and / or Triton X-100.
[0030] Preferably, in the mixed solution, the concentration (v / v) of the surfactant is 1 - 10 μL / mL.
[0031] Preferably, before preparing the interdigital electrode, the flexible substrate is ultrasonically cleaned with ethanol and deionized water in sequence, and the ultrasonication time for each time is 5 - 10 min.
[0032] Preferably, the interdigital electrode is prepared by printing, photolithography or evaporation; the printing includes screen printing, inkjet printing or dispensing. When the interdigital electrode is prepared by screen printing, the interdigital electrode needs to be vacuum dried at 60 - 80 °C for 1 - 3 h; when the interdigital electrode is prepared by inkjet printing, dispensing, photolithography or evaporation, the interdigital electrode does not need to be dried again.
[0033] In a third aspect, the present invention provides the application of the flexible ammonia sensor in nephropathy monitoring.
[0034] Preferably, the operation method for monitoring nephropathy using the flexible ammonia sensor includes the following steps:
[0035] Integrate the flexible ammonia sensor with a microcontroller circuit, realize wireless interaction between the sensor and a smart phone through Bluetooth or WiFi, and use the App on the smart phone to control and display the real-time monitoring information of the ammonia exhaled by nephropathy patients.
[0036] Preferably, the microcontroller is of the STM32 series or the ESP32 series.
[0037] Preferably, the smart phone uses an iOS or Android system.
[0038] Preferably, the App includes but is not limited to blinker.
[0039] Compared with the prior art, the beneficial effects of the present invention are as follows:
[0040] (1) The present invention uses a conductive polymer composite material co-doped with MXene and ionic liquid as the sensing layer, which has a three-dimensional porous honeycomb structure, greatly increasing the contact area between ammonia gas and the sensing film, improving the carrier transport speed, and thus enhancing the sensitivity and response / recovery speed of the sensor; at the same time, by utilizing the catalytic effect of MXene, the electrostatic cross-linking effect of ionic liquid, and the synergistic effect between MXene and ionic liquid and the conductive polymer, it has more excellent sensitivity to low-concentration ammonia gas at room temperature.
[0041] (2) The flexible ammonia sensor of the present invention is prepared at room temperature, with a simple preparation process, low cost, suitable for mass production, and easy to integrate, enabling wireless, intelligent, and real-time monitoring. Description of the Drawings
[0042] Figure 1 is a schematic structural diagram of the flexible ammonia sensor provided by the present invention;
[0043] Figure 2 are SEM images of the sensing layers of the sensors prepared in Example 1 and Comparative Example 1; among them, Figure 2 a is the SEM image of the P sensing layer of the sensor in Example 1; Figure 2 b is the SEM image of the sensing layer of the sensor in Comparative Example 1; Figure 2 c is the SEM image of the PM1 sensing layer of the sensor in Example 1; Figure 2 d is the SEM image of the PM2 sensing layer of the sensor in Example 1; Figure 2 e is the SEM image of the PM3 sensing layer of the sensor in Example 1; Figure 2 f is the SEM image of the PM4 sensing layer of the sensor in Example 1;
[0044] Figure 3 is the cyclic resistance response curve of the flexible sensor prepared in Example 1 to 20 ppm ammonia gas;
[0045] Figure 4 are SEM images of the sensing layers of the sensors prepared in Example 2 and Comparative Example 2; among them, Figure 4 a, Figure 4 b is the SEM image of the sensing layer of the sensor in Comparative Example 2; Figure 4 c, Figure 4 d is the SEM image of the PMB2 sensing layer of the sensor in Example 2;
[0046] Figure 5 are the cyclic resistance response curves of the flexible sensors prepared in Example 1 and Example 2 to 20 ppm ammonia gas;
[0047] Figure 6 Selective test results of the sensor PM2 in Example 1 and the sensor PMB2 in Example 2;
[0048] Figure 7 Cyclic resistance response curves of the flexible sensors prepared in Example 2 and Example 3 to 20 ppm ammonia;
[0049] Figure 8 Cyclic resistance response curve of the flexible sensor prepared in Comparative Example 1 to 20 ppm ammonia;
[0050] Figure 9 Cyclic resistance response curve of the flexible sensor prepared in Comparative Example 2 to 20 ppm ammonia. Detailed implementation manners
[0051] The technical solutions of the present invention will be described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.
[0052] The present invention provides a flexible ammonia sensor for nephropathy monitoring, including: a flexible substrate, interdigital electrodes, and a sensing layer; the interdigital electrodes are located on the surface of the flexible substrate, and the sensing layer covers the interdigital electrodes;
[0053] Wherein, the sensing layer includes a conductive polymer composite material co-doped with MXene and an ionic liquid.
[0054] In some examples, the MXene includes at least one of Ti3C2T x , Nb2CT x , V2CT x ; the ionic liquid includes at least one of 1-vinyl-3-butylimidazolium bromide (VBIMBr), 1-butyl-3-methylimidazolium bromide (BMIMBr), 1-ethyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium tetrafluoroborate; the conductive polymer includes at least one of poly(3,4-ethylenedioxythiophene):polystyrene sulfonate, polyaniline:polystyrene sulfonate, polypyrrole:polystyrene sulfonate.
[0055] In some examples, the thickness of the sensing layer is 100 - 500 nm; the thickness of the interdigital electrode is 1 - 100 μm, the finger width is 10 - 1000 μm, and the spacing between fingers is 10 - 1000 μm. In the following specific embodiments, the thickness of the sensing layer is 200 nm; the thickness of the interdigital electrode is 20 μm, the finger width is 500 μm, and the spacing between fingers is 500 μm.
[0056] In some examples, the flexible substrate includes an organic sheet or fiber; wherein, the organic sheet includes polyethylene terephthalate (PET), polyimide, polyvinylidene fluoride, polymethyl methacrylate, or polycarbonate; the fiber includes cotton, polypropylene, polyester, or polyamide.
[0057] In some examples, the interdigital electrode is prepared from a conductive material, and the conductive material includes at least one of conductive silver paste, graphene, carbon nanotubes, and noble metal materials.
[0058] The preparation method of the flexible ammonia sensor includes the following steps:
[0059] Prepare an interdigital electrode on the surface of the flexible substrate; prepare a composite solution of MXene and ionic liquid co-doped conductive polymer by in-situ polymerization;
[0060] Mix the composite solution of MXene and ionic liquid co-doped conductive polymer with a surfactant uniformly to obtain a mixture, and coat the mixture on the surface of the flexible substrate with an interdigital electrode, and dry to obtain the flexible ammonia sensor.
[0061] The composite solution of MXene and ionic liquid co-doped conductive polymer is prepared by the following method:
[0062] (1) Add a polymer monomer, an oxidant, and polystyrene sulfonate to the MXene dispersion to obtain a mixed reaction solution, and carry out an in-situ polymerization reaction on the mixed reaction solution at room temperature to obtain a mixed solution;
[0063] (2) Dialyze the mixed solution in water for 4 - 8 h to obtain a composite solution of MXene-doped conductive polymer;
[0064] (3) Stir and mix the composite solution of MXene-doped conductive polymer with the ionic liquid at room temperature for 1 - 4 h to cause electrostatic self-assembly to obtain a composite solution of MXene and ionic liquid co-doped conductive polymer.
[0065] In some examples, the concentration of the MXene dispersion is 0.25 to 1 mg / mL; the concentration (v / v) of the polymer monomer in the mixed reaction solution is 0.5 to 25 μL / mL; the concentration (v / v) of the polystyrene sulfonate in the mixed reaction solution is 0.5 to 25 μL / mL; the concentration of the oxidant in the mixed reaction solution is 5 to 50 mg / mL.
[0066] In some examples, in the conductive polymer composite solution co-doped with MXene and ionic liquid, the concentration of the ionic liquid is 20 to 80 mg / mL.
[0067] In some examples, the polymer monomer includes at least one of 3,4-ethylenedioxythiophene, aniline, and pyrrole.
[0068] In some examples, the oxidant includes at least one of ammonium persulfate, iron chloride, and iron sulfate.
[0069] In some examples, the surfactant includes Zonyl FS-300 and / or Triton X-100.
[0070] In some examples, in the mixed solution, the concentration (v / v) of the surfactant is 1 to 10 μL / mL.
[0071] Example 1
[0072] A flexible ammonia sensor for kidney disease monitoring is prepared by the following method:
[0073] (1) Ultrasonically clean the PET sheet with ethanol and deionized water in sequence, ultrasonically clean for 5 minutes each time, and dry with nitrogen.
[0074] (2) Prepare interdigital electrodes on the surface of the PET sheet by screen printing, with a size of 15 mm x 10 mm, a finger width of 500 μm, and a spacing between fingers of 500 μm, and then vacuum dry at 70 °C for 1 h to obtain a flexible substrate coated with interdigital electrodes on the surface.
[0075] (3) Take 20 mL of Ti3C2T x aqueous dispersion (the concentration of the dispersion is 0 mg / mL, 0.25 mg / mL, 0.5 mg / mL, 0.75 mg / mL, or 1 mg / mL), respectively add 110 μL of 3,4-ethylenedioxythiophene, stir at high speed for 5 minutes, then sequentially add 0.3 g of ammonium persulfate and 135 μL of polystyrene sulfonate, and continuously stir at room temperature for 24 h.
[0076] (4) Add the mixed solution obtained in step (3) into a dialysis bag and dialyze it in deionized water for 5 h to obtain Ti3C2T x doped poly(3,4-ethylenedioxythiophene):polystyrene sulfonate solution;
[0077] (5) Take 5 mL of the Ti3C2T x doped poly(3,4-ethylenedioxythiophene):polystyrene sulfonate solution prepared in step (4), add 5 μL of Zonyl FS-300, and stir for 5 min to mix evenly;
[0078] (6) Take 10 μL of the mixed solution in step (5) and drop-coat it on the interdigital area of the flexible substrate. After the liquid droplet spreads fully, place it in a vacuum freeze dryer and freeze-dry it for 12 h to obtain flexible ammonia sensors P (0 mg / mL), PM1 (0.25 mg / mL), PM2 (0.5 mg / mL), PM3 (0.75 mg / mL), and PM4 (1 mg / mL) respectively.
[0079] Figure 2 Figure is the SEM image of the sensing layer of the sensor prepared in Example 1. Among them, Figure 2 a is the SEM image of the sensing layer of sensor P, Figure 2 c is the SEM image of the sensing layer of sensor PM1, Figure 2 d is the SEM image of the sensing layer of sensor PM2, Figure 2 e is the SEM image of the sensing layer of sensor PM3, Figure 2 f is the SEM image of the sensing layer of sensor PM4. As can be seen from the figure, the sensing layer of sensor P without doped Ti3C2T x is a thin film structure, with a rough and uneven surface and a pore structure with uneven distribution. After doping Ti3C2T x the sensing layers of sensors PM1, PM2, PM3, and PM4 present a three-dimensional porous network structure. This structure greatly increases the specific surface area of the sensor and increases the adsorption sites of ammonia, thus being beneficial to improving the sensitivity of the ammonia sensor. Among them, the pore structure of the sensing layer of sensor PM2 is more evenly distributed, which is more conducive to the response of ammonia.
[0080] Integrate the obtained flexible ammonia sensor with the ESP32 single-chip microcomputer circuit, realize the wireless interaction between the sensor and the smart phone through Bluetooth, and use the App - blinker on the smart phone to control the test process and display and alarm the concentration information of ammonia exhaled by nephropathy patients.
[0081] Figure 3 Figure
[0081] is the cyclic resistance response curve of the flexible sensor in Example 1 to 20 ppm ammonia. As can be seen from the figure, without doped Ti3C2T xAfter the sensor P comes into contact with ammonia, its response value gradually increases, but the growth rate is slow, and the highest response value is about 0.1; when it returns to the air environment, its response value slowly decreases, but it is difficult to return to the initial value, and the baseline shifts upward during the subsequent cyclic response process. After doping with Ti3C2T x After that, the response values of sensors PM1, PM2, PM3, and PM4 all increase rapidly to the peak; when it returns to the air environment, the resistance of all sensors rapidly drops to near the initial value, and good stability is presented during the subsequent cyclic response process. In addition, with the increase of Ti3C2T x content, the response value of the sensor shows a trend of first increasing and then decreasing. Among them, the response value of sensor PM2 is the highest, and the response value to 20 ppm ammonia reaches 17.10. The above results show that using the MXene-doped conductive polymer composite as the sensing layer, the obtained sensor has outstanding sensitivity, extremely fast response / recovery, and good stability.
[0082] Example 2
[0083] A flexible ammonia sensor for kidney disease monitoring is prepared by the following method:
[0084] (1) Ultrasonically clean the PET sheet with ethanol and deionized water in turn for 5 minutes each time, and dry it with nitrogen;
[0085] (2) Prepare interdigital electrodes on the surface of the PET sheet by screen printing. Its size is 15 mm x 10 mm, the finger width is 500 μm, and the spacing between fingers is 500 μm. Then dry it in vacuum at 70 °C for 1 h to obtain a flexible substrate with interdigital electrodes coated on the surface;
[0086] (3) Take 20 mL of 0.5 mg / mL Ti3C2T x aqueous dispersion, add 110 μL of 3,4-ethylenedioxythiophene, stir at high speed for 5 minutes, then add 0.3 g of ammonium persulfate and 135 μL of polystyrene sulfonate in turn, and continuously stir at room temperature for 24 h;
[0087] (4) Add the mixed solution obtained in step (3) into a dialysis bag and dialyze it in deionized water for 5 h to obtain a Ti3C2T x -doped poly(3,4-ethylenedioxythiophene): polystyrene sulfonate solution;
[0088] (5) Take 2 mL of the Ti3C2T prepared in step (4) xDoped poly(3,4-ethylenedioxythiophene): polystyrene sulfonate solution, adding 1-vinyl-3-butylimidazolium bromide (the addition amounts are 0.04 g, 0.08 g, 0.12 g or 0.16 g), continuously stirring at room temperature for 2 h, to obtain Ti3C2T x Poly(3,4-ethylenedioxythiophene): polystyrene sulfonate solution co-doped with 1-vinyl-3-butylimidazolium bromide;
[0089] (6) Add 2 μL of Zonyl FS-300 to the solution prepared in step (5), stir for 5 min to mix evenly; add 5 μL of Zonyl FS-300, and continue to stir for 5 min to mix evenly;
[0090] (7) Take 10 μL of the mixed solution prepared in step (6) and drop-coat it on the interdigital area of the flexible substrate. After the droplets are fully spread, place it in a vacuum freeze dryer and freeze-dry for 12 h to obtain flexible ammonia sensors PMB1 (0.04 g), PMB2 (0.08 g), PMB3 (0.12 g), and PMB4 (0.16 g).
[0091] Figure 4 Figures 4c and 4d are SEM images of the sensing layer of the sensor PMB2 prepared in Example 2. It can be seen from the figures that the sensing layer of this flexible sensor has a three-dimensional porous honeycomb structure, with rich active sites and multi-interface conductive channels, which can promote electron transport and significantly improve the sensitivity of the sensor to ammonia.
[0092] Integrate the obtained flexible ammonia sensor with the ESP32 single-chip microcomputer circuit, realize wireless interaction between the sensor and the smart phone through Bluetooth, and use the App - blinker on the smart phone to control the test process and display and alarm the ammonia concentration information exhaled by nephropathy patients.
[0093] Figure 5 Figures are the cyclic resistance response curves of the sensors PM2 in Example 1 and the sensors PMB1, PMB2, PMB3, and PMB4 in Example 2 to 20 ppm ammonia. It can be seen from the figures that after the sensors PMB1, PMB2, PMB3, and PMB4 are exposed to the ammonia atmosphere, the response values all increase rapidly; when restored to the air environment, the response values of all sensors rapidly drop to near the initial value. In addition, with the increase in the content of 1-vinyl-3-butylimidazolium bromide, the response value of the sensor shows a trend of first increasing and then decreasing. Among them, the response value of the sensor PMB2 is the highest, and the response value to 20 ppm ammonia reaches 103.6, which is 6 times the response value of the sensor PM2 (17.10 @ 20 ppm). Figure 6Selectivity test results of the sensor PM2 in Example 1 and the sensor PMB2 in Example 2. As can be seen from the figure, both sensors have good selectivity, and the sensor PMB2 is significantly better than the sensor PM2. The above results indicate that using a conductive polymer composite material co-doped with MXene and ionic liquid as the sensing layer, the obtained sensor has more excellent sensitivity, fast response / recovery, and better selectivity and stability.
[0094] Example 3
[0095] A flexible ammonia sensor for kidney disease monitoring is prepared by the following method:
[0096] (1) Ultrasonically clean the PET sheet with ethanol and deionized water in sequence, ultrasonically clean for 5 min each time, and dry with nitrogen.
[0097] (2) Prepare interdigitated electrodes on the surface of the PET sheet by screen printing. The size is 15 mm x 10 mm, the finger width is 500 μm, and the spacing between fingers is 500 μm. Then vacuum dry at 70 °C for 1 h to obtain a flexible substrate coated with interdigitated electrodes on the surface.
[0098] (3) Take 20 mL of 0.5 mg / mL Ti3C2T x aqueous dispersion, add 110 μL of 3,4-ethylenedioxythiophene, stir at high speed for 5 min, then add 0.3 g of ammonium persulfate and 135 μL of polystyrene sulfonate in sequence, and continuously stir at room temperature for 24 h.
[0099] (4) Add the mixed solution obtained in step (3) into a dialysis bag and dialyze in deionized water for 5 h to obtain a Ti3C2T x doped poly(3,4-ethylenedioxythiophene):polystyrene sulfonate solution.
[0100] (5) Take 2 mL of the Ti3C2T x doped poly(3,4-ethylenedioxythiophene):polystyrene sulfonate solution prepared in step (4), add 0.08 g of 1-butyl-3-methylimidazolium bromide, and continuously stir at room temperature for 2 h to obtain a Ti3C2T x and 1-butyl-3-methylimidazolium bromide co-doped poly(3,4-ethylenedioxythiophene):polystyrene sulfonate solution.
[0101] (6) Add 2 μL of Zonyl FS-300 to the solution prepared in step (5), stir for 5 min to mix evenly; add 5 μL of Zonyl FS-300, and continue to stir for 5 min to mix evenly.
[0102] (7) Take 10 μL of the mixed solution prepared in step (6) and drop it onto the interdigital area of the flexible substrate. After the droplet has fully spread, place it in a vacuum freeze dryer and freeze-dry it for 12 h to obtain a flexible ammonia sensor.
[0103] Integrate the obtained flexible ammonia sensor with the ESP32 single-chip microcomputer circuit, realize wireless interaction between the sensor and the smartphone through Bluetooth, and use the App - blinker on the smartphone to control the testing process and display and alarm the ammonia concentration information exhaled by nephropathy patients.
[0104] Figure 7 For the cyclic resistance response curves of the sensor PMB2 in Example 2 and the flexible sensor in Example 3 to 20 ppm ammonia, as can be seen from the figure, the response value of the VBIMBr-doped sensor is about twice that of the BMIMBr-doped sensor. This result indicates that the VBIMBr-doped sensor prepared in Example 2 has better sensitivity to ammonia.
[0105] Comparative Example 1
[0106] (1) Ultrasonically clean the PET sheet with ethanol and deionized water in turn, ultrasonically clean for 5 min each time, and dry it with nitrogen.
[0107] (2) Prepare interdigital electrodes on the surface of the PET sheet by screen printing. The size is 15 mm x 10 mm, the finger width is 500 μm, and the spacing between fingers is 500 μm. Then dry it in vacuum at 70 °C for 1 h to obtain a flexible substrate with interdigital electrodes coated on the surface.
[0108] (3) Take 20 mL of deionized water, add 110 μL of 3,4-ethylenedioxythiophene, stir at high speed for 5 min, and then add 0.3 g of ammonium persulfate and 135 μL of polystyrene sulfonate in turn, and continuously stir at room temperature for 24 h.
[0109] (4) Add the solution obtained in step (3) into a dialysis bag and dialyze it in deionized water for 5 h to obtain a poly(3,4-ethylenedioxythiophene):polystyrene sulfonate solution, and add 10 mg of Ti3C2T x powder, stir well to make it evenly mixed.
[0110] (5) Take 5 mL of the Ti3C2T x - doped poly(3,4-ethylenedioxythiophene):polystyrene sulfonate solution, add 5 μL of Zonyl FS-300, and stir for 5 min to make it evenly mixed.
[0111] (6) Take 10 µL of the mixed solution from step (5) and drop it onto the interdigital area of the flexible substrate. After the droplet spreads fully, place it in a vacuum freeze dryer and freeze-dry for 12 h to obtain a flexible ammonia sensor.
[0112] Integrate the obtained flexible ammonia sensor with the ESP32 single-chip microcomputer circuit, realize wireless interaction between the sensor and the smartphone through Bluetooth, and use the App - blinker on the smartphone to control the testing process and display and alarm the ammonia concentration information exhaled by nephropathy patients.
[0113] Figure 2 b is the SEM image of the sensing layer of the sensor prepared in Comparative Example 1. It can be seen from the figure that the sensing layer prepared by the blending method presents a coral shape and visible microcracks, which is not conducive to forming a stable sensing channel. Figure 8 It is the cyclic resistance response curve of the flexible sensor prepared in Comparative Example 1 to 20 ppm ammonia. It can be seen from the figure that the response value of the sensor prepared by the blending method is much lower than that of the sensor prepared by the in-situ polymerization method of the present invention.
[0114] Comparative Example 2
[0115] (1) Ultrasonically clean the PET sheet with ethanol and deionized water in sequence, ultrasonically clean for 5 min each time, and dry with nitrogen.
[0116] (2) Prepare interdigital electrodes on the surface of the PET sheet by screen printing. Its size is 15 mm x 10 mm, the finger width is 500 μm, and the spacing between fingers is 500 μm. Then dry it in vacuum at 70 °C for 1 h to obtain a flexible substrate with interdigital electrodes coated on the surface.
[0117] (3) Take 20 mL of deionized water, add 110 µL of 3,4-ethylenedioxythiophene, stir at high speed for 5 min, then add 0.3 g of ammonium persulfate and 135 µL of polystyrene sulfonate in sequence, and continuously stir at room temperature for 24 h.
[0118] (4) Add the solution obtained in step (3) into a dialysis bag and dialyze in deionized water for 5 h to obtain a poly(3,4-ethylenedioxythiophene):polystyrene sulfonate solution.
[0119] (5) Take 2 mL of the poly(3,4-ethylenedioxythiophene):polystyrene sulfonate solution prepared in step (4), add 0.08 g of 1-vinyl-3-butylimidazolium bromide, and continuously stir at room temperature for 2 h to obtain a 1-vinyl-3-butylimidazolium bromide-doped poly(3,4-ethylenedioxythiophene):polystyrene sulfonate solution. Add 2 µL of Zonyl FS-300 to the above-prepared solution and stir for 5 min to make it evenly mixed.
[0120] (6) Take 10 μL of the mixed solution in step (5) and drop-coat it on the interdigital area of the flexible substrate. After the droplet spreads sufficiently, place it in a vacuum freeze dryer and freeze-dry it for 12 h to obtain the flexible ammonia sensor PB2.
[0121] Integrate the obtained flexible ammonia sensor with the ESP32 single-chip microcomputer circuit, realize wireless interaction between the sensor and the smart phone through Bluetooth, and use the App - blinker on the smart phone to control the test process and display and alarm the ammonia concentration information exhaled by nephropathy patients.
[0122] Figure 4 a and Figure 4 b are SEM images of the sensing layer of the sensor prepared in Comparative Example 2. As can be seen from the figure, the sensing layer of this sensor presents an irregularly wrinkled film structure. Compared with the three-dimensional porous honeycomb structure, this structure is not conducive to the full contact of ammonia with the sensing material. Figure 9 is the cyclic resistance response curve of the flexible sensor prepared in Comparative Example 2 to 20 ppm ammonia. As can be seen from the figure, the sensor PB2 shows good sensitivity, but it is still significantly lower than the flexible sensor prepared in Example 2.
[0123] In summary, the present invention uses a conductive polymer composite material co-doped with MXene and ionic liquid as the sensing layer. The conductive polymer composite material co-doped with MXene and ionic liquid has a three-dimensional porous honeycomb structure, which has an extremely high specific surface area and is conducive to the full contact of ammonia with the sensing film, thereby helping to improve the sensitivity of the sensor. The flexible ammonia sensor of the present invention has excellent sensitivity, an extremely low detection limit (ppb level), fast response / recovery, good selectivity and stability, and can realize real-time monitoring of the ammonia concentration exhaled by nephropathy patients.
[0124] The above specific embodiments have described the implementation of the present invention in detail. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the claims and technical concept of the present invention, various simple modifications and changes can be made to the technical solution of the present invention, and these simple variants all belong to the protection scope of the present invention.
Claims
1. A flexible ammonia sensor for kidney disease monitoring, characterized in that, Comprising: A flexible substrate, interdigital electrodes, and a sensing layer; wherein, the sensing layer comprises a conductive polymer composite material co-doped with MXene and an ionic liquid.
2. The flexible ammonia sensor for nephropathy monitoring according to claim 1, characterized in that, The MXene includes at least one of Ti3C2T x , Nb2CT x , V2CT x ; the ionic liquid includes at least one of 1-vinyl-3-butylimidazolium bromide, 1-butyl-3-methylimidazolium bromide, 1-ethyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium tetrafluoroborate; the conductive polymer includes at least one of poly(3,4-ethylenedioxythiophene): polystyrenesulfonate, polyaniline: polystyrenesulfonate, polypyrrole: polystyrenesulfonate.
3. The flexible ammonia sensor for nephropathy monitoring according to claim 1, characterized in that, The thickness of the sensing layer is 100 - 500 nm; the thickness of the interdigital electrodes is 1 - 100 μm, the finger width is 10 - 1000 μm, and the spacing between fingers is 10 - 1000 μm.
4. The preparation method of a flexible ammonia sensor for nephropathy monitoring according to any one of claims 1 to 3, characterized in that, Including the following steps: Preparing interdigital electrodes on the surface of the flexible substrate; preparing a conductive polymer composite solution co-doped with MXene and an ionic liquid by in-situ polymerization. Mixing the conductive polymer composite solution co-doped with MXene and an ionic liquid with a surfactant uniformly to obtain a mixed solution, coating the mixed solution on the surface of the flexible substrate with interdigital electrodes, and drying to obtain a flexible ammonia sensor.
5. The preparation method of a flexible ammonia sensor for nephropathy monitoring according to claim 4, characterized in that, The conductive polymer composite solution co-doped with MXene and an ionic liquid is prepared by the following method: (1) Adding a polymer monomer, an oxidant, and polystyrene sulfonate to the MXene dispersion liquid to obtain a mixed reaction solution, and carrying out an in-situ polymerization reaction on the mixed reaction solution at room temperature to obtain a mixed solution. (2) Dialyzing the mixed solution to obtain a conductive polymer composite solution doped with MXene. (3) Mixing the conductive polymer composite solution doped with MXene with an ionic liquid at room temperature to obtain a conductive polymer composite solution co-doped with MXene and an ionic liquid.
6. The preparation method of a flexible ammonia sensor for nephropathy monitoring according to claim 5, characterized in that, The concentration of the MXene dispersion liquid is 0.25 - 1 mg / mL; the concentration (v / v) of the polymer monomer in the mixed reaction solution is 0.5 - 25 μL / mL; the concentration (v / v) of the polystyrene sulfonate in the mixed reaction solution is 0.5 - 25 μL / mL.
7. The preparation method of a flexible ammonia sensor for nephropathy monitoring according to claim 5, characterized in that, In the conductive polymer composite solution co-doped with MXene and an ionic liquid, the concentration of the ionic liquid is 20 - 80 mg / mL.
8. The preparation method of a flexible ammonia sensor for kidney disease monitoring according to claim 5, characterized in that, The polymer monomer includes at least one of 3,4-ethylenedioxythiophene, aniline, and pyrrole.
9. The application of the flexible ammonia sensor according to any one of claims 1 - 3 in the monitoring of kidney diseases.
10. Use of the flexible ammonia sensor according to claim 9 in nephropathy monitoring, characterized in that, The application method includes: Integrating the flexible ammonia sensor with a single-chip microcomputer circuit, realizing wireless interaction between the sensor and a smart phone through Bluetooth or WiFi, and using the App on the smart phone to control and display the real-time monitoring information of the ammonia exhaled by kidney disease patients.