Flexible ammonia gas sensor and preparation method thereof

Abstract

The invention relates to a flexible ammonia gas sensor and a preparation method thereof, and the preparation method comprises the following steps: self-growing TiO2 on the surface of Ti3C2Tx through a hydrothermal method to obtain a Ti3C2Tx / TiO2 sensitive body material; the method comprises the following steps: acquiring a flexible substrate, and preprocessing the flexible substrate; preparing an interdigital electrode on the upper surface of the pretreated flexible substrate; and depositing the Ti3C2Tx / TiO2 sensitive body material on the upper surface of the interdigital electrode to obtain the flexible ammonia gas sensor. The flexible ammonia gas sensor prepared by the preparation method provided by the embodiment of the invention can be suitable for ammonia gas detection when a human body exhales, is small in size, low in cost and good in mechanical stability, and can be integrated in wearable equipment as a flexible structure.

Description

Technical Field

[0001] The present invention belongs to the technical field of ammonia detection, and particularly relates to a flexible ammonia gas sensor and a preparation method thereof. Background Art

[0002] With the breakthrough of technology and the popularization of clinical applications, non-invasive exhaled gas detection has become a new auxiliary diagnosis method in the field of gastric cancer. As a biomarker for kidney diseases, the concentration of ammonia will affect the detection effect of gastric cancer gas biomarkers. Therefore, it is necessary to detect the ammonia concentration and exclude its signal to achieve effective detection of gastric cancer gas biomarkers.

[0003] Currently, the devices for detecting ammonia are generally large in size, heavy in weight, and complex in operation, which to a certain extent limits their application in the medical field. In recent years, miniaturized semiconductor gas sensors have gradually emerged in the field of gas detection and have given rise to a variety of portable instruments.

[0004] However, traditional semiconductor gas sensors need to operate in a high-temperature range (150 - 300 °C), so they must be equipped with an internal micro-heater, resulting in a complex device structure. In addition, working in a high-temperature environment for a long time may damage the device, making it difficult to meet the requirements of long-term detection in clinical applications. Summary of the Invention

[0005] In order to solve the above problems existing in the prior art, the present invention provides a flexible ammonia gas sensor and a preparation method thereof. The technical problems to be solved by the present invention are achieved through the following technical solutions:

[0006] The first aspect of the present invention provides a preparation method of a flexible ammonia gas sensor, comprising the following steps:

[0007] Self-grow TiO 3 C 2 T x on the surface of Ti 2 to obtain a Ti 3 C 2 T x / TiO 2 sensitive material;

[0008] Obtain a flexible substrate and pre-treat the flexible substrate;

[0009] Prepare interdigital electrodes on the upper surface of the pre-treated flexible substrate;

[0010] Place the Ti 3 C 2 T x / TiO 2The sensitive material is deposited on the upper surface of the interdigital electrode to obtain a flexible ammonia gas sensor.

[0011] In an achievable manner, TiO is self-grown on the surface of Ti 3 C 2 T x , including: 2 :

[0012] Disperse Ti 3 C 2 T x in a NaBF solution with a concentration of 0.1 M to obtain a first mixed solution; 4 :

[0013] Add dilute acid to the first mixed solution and stir until dissolved at room temperature to obtain a second mixed solution;

[0014] Place the second mixed solution in a high-pressure vessel and carry out a hydrothermal reaction at a temperature of 150 - 200 °C to in-situ convert part of Ti 3 C 2 T x into TiO 2 .

[0015] In an achievable manner, the ratio of the Ti 3 C 2 T x to the NaBF with a concentration of 0.1 M 4 is 100 mg: 12.8 - 16 ml.

[0016] In an achievable manner, the pH of the second mixed solution is less than or equal to 1.

[0017] In an achievable manner, the reaction time of the hydrothermal reaction is 9 - 13 h.

[0018] In an achievable manner, the flexible substrate is pretreated, including:

[0019] Perform plasma treatment on the surface of the flexible substrate.

[0020] In an achievable manner, an interdigital electrode is prepared on the upper surface of the pretreated flexible substrate, including:

[0021] Print an interdigital electrode on the upper surface of the pretreated flexible substrate; the interdigital spacing of the interdigital electrode is 0.08 - 0.12 cm, and the number of interdigital pairs is 5 - 7 pairs.

[0022] In an achievable manner, the material of the flexible substrate includes: PET, PDMS, PI or PEN.

[0023] In an implementable manner, depositing the Ti 3 C 2 T x / TiO 2 sensitive material on the upper surface of the interdigital electrode, including:

[0024] By one of PVD process, coating process, spin coating process and CVD process, depositing the Ti 3 C 2 T x / TiO 2 sensitive material on the upper surface of the interdigital electrode.

[0025] The second aspect of the present invention provides a flexible ammonia gas sensor prepared by the preparation method provided in the first aspect of the present invention, including:

[0026] A flexible substrate, an interdigital electrode and Ti 3 C 2 T x / TiO 2 sensitive material arranged in sequence from bottom to top.

[0027] Compared with the prior art, the beneficial effects of the present invention:

[0028] The present invention provides a flexible ammonia gas sensor and its preparation method. By hydrothermal method, TiO 3 C 2 T x is self-grown on the surface of Ti 2 to obtain Ti 3 C 2 T x / TiO 2 sensitive material, and preparing the Ti 3 C 2 T x / TiO 2 sensitive material on a flexible substrate to obtain a flexible ammonia gas sensor. The flexible ammonia gas sensor prepared by the preparation method provided in this embodiment has a low detection limit for ammonia, high sensitivity, high selectivity, good stability, can respond and recover quickly, can still meet the application in a high humidity environment, is applicable to the detection of ammonia in human exhalation, and has a small volume, low cost and good mechanical stability, and can be integrated as a flexible structure inside a wearable device. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 is a flowchart of a preparation method of a flexible ammonia gas sensor provided by an embodiment of the present invention;

[0030] Figure 2It is a schematic structural diagram of a flexible ammonia gas sensor provided by an embodiment of the present invention;

[0031] Figure 3 It is the X-ray diffraction pattern of sample S3;

[0032] Figure 4 It is the scanning electron microscope images of sample S1 and sample S3;

[0033] Figure 5 It is the specific surface area test chart of sample S1 and sample S3;

[0034] Figure 6 It is the bar chart of the response values of sample S1 and sample S3;

[0035] Figure 7 It is the dynamic response and recovery curve of the flexible ammonia gas sensor provided by an embodiment of the present invention to 100 ppm ammonia at room temperature;

[0036] Figure 8 It is the dynamic response and recovery curve of the flexible ammonia gas sensor provided by an embodiment of the present invention to ammonia at different concentrations at room temperature;

[0037] Figure 9 It is the five consecutive dynamic response and recovery curves of the flexible ammonia gas sensor provided by an embodiment of the present invention to 100 ppm ammonia at room temperature;

[0038] Figure 10 It is the response value chart of the flexible ammonia gas sensor provided by an embodiment of the present invention continuously for 30 days at room temperature;

[0039] Figure 11 It is the response value chart of the flexible ammonia gas sensor provided by an embodiment of the present invention to different gases at room temperature;

[0040] Figure 12 It is the response value chart of the flexible ammonia gas sensor provided by an embodiment of the present invention to 100 ppm ammonia at different humidities at room temperature;

[0041] Figure 13 It is the dynamic response and recovery curve chart of the flexible ammonia gas sensor provided by an embodiment of the present invention to 100 ppm ammonia at different bending angles (0° - 90°) at room temperature;

[0042] Figure 14 It is the dynamic response and recovery curve of the flexible ammonia gas sensor provided by an embodiment of the present invention to 100 ppm ammonia after different bending times;

[0043] Figure 15 It is the schematic diagram of the structure and performance of the flexible ammonia gas sensor provided by an embodiment of the present invention integrated into the internal part of a gas mask filter cartridge. Detailed Embodiments

[0044] The following describes the present invention in further detail with reference to specific embodiments, but the embodiments of the present invention are not limited thereto.

[0045] Embodiment 1

[0046] Please refer to Figure 1 , Figure 1 which is a flowchart of a preparation method of a flexible ammonia gas sensor provided by an embodiment of the present invention.

[0047] A preparation method of a flexible ammonia gas sensor provided in the first aspect of this embodiment includes the following steps:

[0048] S1: Hydrothermally grow TiO 3 C 2 T x on the surface of Ti 2 C 3 T 2 T x / TiO 2 sensitive material.

[0049] In this embodiment, hydrothermally growing TiO 3 C 2 T x on the surface of Ti 2 includes:

[0050] S101: Disperse Ti 3 C 2 T x in a NaBF 4 solution with a concentration of 0.1 M to obtain a first mixed solution.

[0051] In this embodiment, the ratio of Ti 3 C 2 T x to NaBF 4 with a concentration of 0.1 M is 100 mg: 12.8 - 16 ml.

[0052] Specifically, Ti 3 C 2 T x is the precursor, and NaBF 4 is used to moderately oxidize Ti 3 C 2 T x to improve the flexibility, strength and stability of the material, better combine with the flexible substrate, and enhance the mechanical stability of the flexible sensor. In this embodiment, NaBF 4 is a single variable, and by adjusting NaBF4 The amount of Ti obtained by changing 3 C 2 T x / TiO 2 The growth morphology of the sensitive material, so as to obtain TiC 3 C 2 T x / TiO 2 sensitive material that meets the application of flexible ammonia gas sensors. Further, Ti 3 C 2 T x is the (002) crystal plane, and TiO 2 is the (101) crystal plane. The surface of (002) Ti 3 C 2 T x is rich in hydroxyl groups and oxygen functional groups, which can enhance the adsorption of gas molecules and has a stronger adsorption capacity for reducing gases (such as ammonia) at room temperature. Moreover, (002) Ti 3 C 2 T x has higher conductivity, can effectively conduct electrons, and improve the response speed and sensitivity of the gas sensor. A large number of Ti atomic defects will be generated during the oxidation process of (002) Ti 3 C 2 T x These defect sites can significantly enhance the adsorption capacity of gas molecules. (101) TiO 2 is composed of four-coordinated Ti 4+ and O 2- and has a compact structure with high stability. It can adsorb ammonia through the oxygen vacancies on the surface and has a poor adsorption capacity for ammonia, but has long-term durability. Therefore, (002) Ti 3 C 2 T x and (101) TiO 2 combined can achieve long-term stable and highly sensitive ammonia adsorption performance.

[0053] S102: Add dilute acid to the first mixed solution and stir at room temperature until dissolved to obtain a second mixed solution.

[0054] Specifically, the pH of the second mixed solution is less than or equal to 1. The dilute acid includes dilute hydrochloric acid, and the solution is adjusted to strong acidity by the dilute acid.

[0055] S103: Place the second mixed solution in a high-pressure container and carry out a hydrothermal reaction at a temperature of 150 - 200 °C to in-situ convert part of Ti 3 C 2 T x into TiO 2 .

[0056] After S103, it is cooled to room temperature, washed, and vacuum dried to obtain Ti 3 C 2 T x / TiO 2 sensitive material.

[0057] Specifically, the reaction time of the hydrothermal reaction is 9 - 13 h. During the hydrothermal reaction, part of the Ti 3 C 2 T x is in-situ transformed into TiO 2 , realizing the self-growth of TiO 2 , and obtaining Ti 3 C 2 T x / TiO 2 sensitive material. TiO 2 , as an n-type semiconductor material, forms a p-n heterojunction when contacting with Ti 3 C 2 T x . When NH 3 is adsorbed on the surface of the Ti 3 C 2 T x / TiO 2 sensitive material, TiO 2 releases electrons, and part of the electrons are transferred to Ti 3 C 2 T x , changing the overall conductivity of the material, thereby realizing ammonia detection. Moreover, Ti 3 C 2 T x has high conductivity and abundant surface functional groups (such as -O, -OH, -F), which can provide active sites for adsorbing NH 3 . NH 3 , as a reducing gas, reacts with the oxides or adsorbed oxygen on the surface of Ti 3 C 2 T x , resulting in electron transfer and causing a change in the conductivity of Ti 3 C 2 T x . Ti 3 C 2 T x can exhibit excellent gas-sensing performance at room temperature, with a high response value to ammonia and a short recovery time. Ti 3 C 2 T x / TiO 2The band gap of the sensitive material is small, and electrons are more likely to be excited from the valence band to the conduction band, further improving the sensitivity of the sensor to ammonia.

[0058] Furthermore, TiO is self-grown on the surface of Ti 3 C 2 T x by hydrothermal method, which can increase the specific surface area of the material and provide more active sites for the ammonia adsorption reaction. The higher content of adsorbed oxygen on the surface of the Ti 2 C 3 C 2 T x / TiO 2 sensitive material surface increases the possibility of redox reactions occurring on the material surface, thereby improving the gas-sensing performance of the material. The higher content of acidic adsorption sites on the surface of the Ti 3 C 2 T x / TiO 2 sensitive material surface enables the material surface to adsorb more basic gases, improving the selectivity to ammonia at room temperature.

[0059] S2: Obtain a flexible substrate and pre-treat the flexible substrate.

[0060] In this embodiment, the materials of the flexible substrate include: polyethylene terephthalate (PET), polydimethylsiloxane (PDMS), polyimide (PI) or polyethylene naphthalate (PEN).

[0061] In this embodiment, pre-treating the flexible substrate includes:

[0062] Performing plasma treatment on the surface of the flexible substrate.

[0063] S3: Fabricate interdigital electrodes on the upper surface of the pre-treated flexible substrate.

[0064] In this embodiment, fabricating interdigital electrodes on the upper surface of the pre-treated flexible substrate includes:

[0065] Printing interdigital electrodes on the upper surface of the pre-treated flexible substrate; the interdigital spacing of the interdigital electrodes is 0.08 - 0.12 cm, and the number of interdigital pairs is 5 - 8 pairs.

[0066] Specifically, an inkjet printer is used to print interdigital electrodes on a plasma-treated flexible substrate. Reducing the spacing between the interdigital electrodes increases the electric field strength between the electrodes, making it easier for gas molecules to react with the electrode surface, thereby improving the gas detection ability of the sensor and significantly enhancing the sensitivity of the sensor. Reducing the interdigital spacing can also make the resistance change between the electrodes more obvious, thus enhancing the signal strength, while the influence of noise will be relatively reduced. Reducing the interdigital electrode spacing leads to a more concentrated electric field distribution and an increased electric field strength, which helps to improve the interaction between gas molecules and the electrode surface, thereby improving the performance of the sensor. In addition, a smaller interdigital spacing helps to accelerate the response speed of the sensor because the diffusion path of gas molecules between the electrodes becomes shorter and the diffusion time is reduced, enabling the sensor to reach a stable state faster. However, an overly small spacing is prone to causing electrode fracture or short circuit during bending and has high requirements for the process. Increasing the number of pairs of interdigital electrodes can increase the total surface area of the electrodes, thereby providing more active sites, increasing the adsorption amount of gas molecules, enabling more gas molecules to react with the electrodes, and thus enhancing the detection ability and sensitivity of the sensor. However, excessive increase in the number of pairs will increase the manufacturing complexity and cost, and at the same time will also increase the mutual interference between the electrodes. Therefore, to meet the application of flexible sensors, avoid electrode failure during bending, and ensure the stability and sensitivity of the sensor, in this embodiment, the interdigital spacing of the interdigital electrodes is set to 0.08 - 0.12 cm, and the number of pairs of interdigital electrodes is 5 - 8 pairs.

[0067] Furthermore, an inkjet printer (spraying method) is a simple and scalable coating process that can fabricate nanocomposites on various flexible / stretchable substrates. It can be evenly distributed during the spraying process to form a nanocomposite with good conductivity and flexibility, without the need for complex equipment such as photolithography or electron beam evaporation, reducing the scrap rate and cost during the preparation process. The spraying method can achieve uniform coating over a large area, is suitable for preparing large-area flexible devices, can prepare nanocomposites with high conductivity and flexibility, can enhance the mechanical stability of flexible devices, and improve the washability and durability of flexible devices.

[0068] S4: Deposit the Ti 3 C 2 T x / TiO 2 sensitive material on the upper surface of the interdigital electrodes to obtain a flexible ammonia gas sensor.

[0069] In this embodiment, depositing the Ti 3 C 2 T x / TiO 2 sensitive material on the upper surface of the interdigital electrodes includes:

[0070] By one of physical vapor deposition (PVD) process, coating process, spin coating process and chemical vapor deposition (CVD) process, deposit Ti 3 C 2 T x / TiO 2 sensitive material on the upper surface of the interdigital electrode.

[0071] Please refer to Figure 2 , Figure 2 which is a schematic structural diagram of a flexible ammonia gas sensor provided by an embodiment of the present invention.

[0072] The second aspect of this embodiment provides a flexible ammonia gas sensor, which is prepared by the preparation method provided in the first aspect of this embodiment, and includes:

[0073] A flexible substrate, an interdigital electrode, and Ti 3 C 2 T x / TiO 2 sensitive material are arranged in sequence from bottom to top. Ti 3 C 2 T x / TiO 2 sensitive material is deposited on the upper surface of the interdigital electrode, Figure 2 which is not shown in

[0074] This embodiment provides a flexible ammonia gas sensor and its preparation method. By means of a hydrothermal method, TiO 3 C 2 T x is self-grown on the surface of 2 to obtain Ti 3 C 2 T x / TiO 2 sensitive material, and the Ti 3 C 2 T x / TiO 2 sensitive material is prepared on the flexible substrate to obtain a flexible ammonia gas sensor. The flexible ammonia gas sensor prepared by the preparation method provided in this embodiment has a low detection limit for ammonia, high sensitivity, high selectivity, good stability, can respond and recover quickly, can still meet the application in a high humidity environment, is applicable to the detection of ammonia in human exhalation, and has a small volume, low cost and good mechanical stability, and can be integrated as a flexible structure inside wearable devices.

[0075] Example Two

[0076] Based on Embodiment 1, this embodiment provides a flexible ammonia gas sensor and its preparation method, and conducts performance tests on the flexible ammonia gas sensor provided in this embodiment to further illustrate its performance. The flexible ammonia gas sensor provided in this embodiment includes: a PET flexible substrate, silver interdigital electrodes, and Ti 3 C 2 T x / TiO 2 sensitive material.

[0077] The preparation method of the flexible ammonia gas sensor provided in the embodiment includes the following steps:

[0078] Step 1: Weigh 100 mg of Ti 3 C 2 T x and disperse it in 16 ml of a solution with a concentration of 0.1 M NaBF 4 to obtain a first mixed solution. Add 16 ml of dilute hydrochloric acid to the first mixed solution and stir at room temperature until dissolved to obtain a second mixed solution. Transfer the second mixed solution to a 50 ml Teflon-lined stainless steel autoclave and carry out a hydrothermal reaction in an oven at 160 °C for 12 h. After the reaction, cool to room temperature, wash, and dry in vacuum to obtain Ti 3 C 2 T x / TiO 2 sensitive material. Denote the Ti 3 C 2 T x / TiO 2 sensitive material in this embodiment as sample S3; and use the same preparation method but without adding NaBF 4 (dissolve Ti 3 C 2 T x in water) to prepare a comparative example, denoted as sample S1.

[0079] Step 2: Obtain a PET material as a flexible substrate and perform plasma treatment on the surface of the flexible substrate.

[0080] Step 3: Print silver interdigital electrodes on the plasma-treated flexible substrate using an inkjet printer. The size of the silver interdigital electrodes is 2 cm * 1.3 cm, the interdigital spacing is 0.1 cm, and the number of interdigital pairs is 6 pairs.

[0081] Step 4: Place Ti 3 C 2 T x / TiO 2The sensitive material is dispersed in deionized water (DI) to obtain a dispersion solution. The dispersion solution is placed in an ultrasonic machine and ultrasonicated for 5 minutes to mix evenly. The evenly mixed dispersion solution is placed in a PVD liquid container, and Ti is deposited on the interdigital electrode by spraying method. 3 C 2 T x / TiO 2 sensitive material thin film. Finally, the substrate containing the Ti 3 C 2 T x / TiO 2 sensitive material thin film is vacuum dried at 50 °C for 12 h to obtain a flexible ammonia gas sensor.

[0082] Specifically, samples S1 and S3 are characterized, and the performance of the flexible ammonia gas sensor provided in this example (prepared from sample S3) is tested. Please refer to Figures 3 to 6 , Figure 3 which is the X-ray diffraction pattern of sample S3. The diffraction peaks at 2θ = 8.68° and 61.65° correspond to the (002) and (110) crystal planes, which are consistent with the standard PDF card of Ti 3 C 2 T x . The diffraction peaks at 2θ = 25.46°, 37.79°, 48.15°, 53.87° and 55.13° correspond to the (101), (004), (200), (105) and (211) crystal planes of TiO 2 (PDF#4-477). The decrease in the intensity of the (002) peak of Ti 3 C 2 T x and the increase in the diffraction peaks of TiO 2 are related to oxidation. The shift of the (002) peak of Ti 3 C 2 T x to a lower angle is due to the addition of TiO 2 , indicating the successful preparation of the Ti 3 C 2 T x / TiO 2 sensitive material. Figure 4 In (a) is the scanning electron microscope image of sample S1, in which the accordion-like structure of Ti 3 C 2 T x can be seen, and very little TiO 3 C 2 T x grows on Ti 2 ; Figure 4 In (b) is the scanning electron microscope image of sample S3, and it can be seen that TiO2 The nanosheets grow uniformly on the surface of Ti 3 C 2 T x surface. It can be seen from Figure 5 that sample S3 has a large specific surface area, which can provide more adsorption sites for gases and effectively improve the sensitivity of the sensor. It can be seen from Figure 6 that sample S3 has a high response to 100 ppm ammonia, and the response value is 102.02%.

[0083] Furthermore, use a Fluke 8846a high-precision digital multimeter to measure the resistance values of the flexible ammonia gas sensor provided in this embodiment in different environments, and the results are as Figures 7 to 15 shown. It can be seen from Figure 7 that when the flexible ammonia gas sensor provided in this embodiment is at room temperature and exposed to an ammonia atmosphere of 100 ppm, the resistance increases sharply; when the sensor is exposed to an air environment, the resistance decreases slowly. According to the time required for the sensor to reach 90% of the resistance change during the response and recovery stages to ammonia, calculate the response time (tres) and recovery time (trec) of the sensor. The response time (tres) of the sensor to ammonia is 105 s, and the recovery time (trec) is 630 s. It can be seen from Figure 8 that when the flexible ammonia gas sensor provided in this embodiment is at room temperature and the ammonia concentration is in the range of 100 ppb to 150 ppm, as the ammonia concentration increases, the response of the sensor shows an upward trend, showing strong response and recovery characteristics. When the ammonia concentration is 100 ppb, the response value reaches 6.87%, which indicates that the flexible ammonia gas sensor provided in this embodiment has a low detection limit. It can be seen from Figure 9 that after each response / recovery, the sensor can repeat the response / recovery process, and the response value to ammonia shows consistency, indicating that the sensor has good repeatability. It can be seen from Figure 10 that the sensor provided in this embodiment has good stability to 100 ppm ammonia under stable conditions (25 °C, 40% RH), and the response fluctuation of the sensor within 30 days is within 20%, indicating that the sensor has long-term stability. It can be seen from Figure 11 that among the seven target gases with a concentration of 100 ppm (carbon dioxide, formaldehyde, benzene, acetone, nitrogen dioxide, hydrogen sulfide ion, carbon monoxide and ammonia), the sensor provided in this embodiment has the highest sensitivity to ammonia, and the sensor has high selectivity to ammonia. It can be seen from Figure 12 that when the humidity increases from 40% RH to 90% RH, the sensor response fluctuates within 20%. The sensor provided in this embodiment meets the application requirements in a high-humidity environment (human exhalation).

[0084] The flexible ammonia gas sensor provided by this embodiment has a low detection limit for ammonia, high sensitivity, high selectivity, good stability, can respond and recover quickly, and can still meet the application requirements in a high-humidity environment, and is applicable to the detection of ammonia in human exhalation.

[0085] Figure 13 and Figure 14 characterize the bending performance and mechanical stability of the flexible ammonia gas sensor provided by this embodiment. It can be seen from Figure 13 that when the bending angles are 0°, 30°, 60°, and 90°, the responses of the sensor provided by this embodiment to 100 ppm ammonia are 102.02%, 99.14%, 98.78%, and 91.37% respectively. As the bending angle increases, the sensitivity of the sensor weakens within an acceptable range, which has no impact on subsequent applications and meets the requirements of flexible devices. It can be seen from Figure 14 that when bent at 60° at room temperature, the sensor response of the sensor provided by this embodiment changes little after being bent 1000 times, indicating that the sensor has good mechanical stability.

[0086] The flexible ammonia sensor provided by this embodiment has good mechanical stability and can still maintain good ammonia detection performance after being folded multiple times, and can meet the requirements of being integrated inside wearable structures. Please refer to Figure 15 , Figure 15 where (a) shows a schematic diagram of the sensor provided by this embodiment integrated into the filter element of a gas mask, which shows an actual application case of the sensor provided by this embodiment. Figure 15 where (b) shows the response curves of the sensor provided by this embodiment to ammonia when integrated inside different types of gas masks. When the external NH 3 concentration is 100 ppm, all the corresponding concentrations inside the five gas masks drop to below the 1 ppm level. The responses of the five gas masks integrated with the sensor provided by this embodiment to ammonia are 17.53%, 3.77%, 4.37%, 1.07%, and 2.68% respectively. Since the first gas mask has a better protection effect against ammonia, the response of the sensor integrated inside the first gas mask is quite different from the others. The responses of the sensor provided by this embodiment to ammonia when integrated inside different types of gas masks all meet the requirements and can be applied to be integrated inside gas masks to monitor the performance of gas masks in real time when NH 3 leaks. It can also be applied to clinically monitor the content of interfering gases (ammonia) in human exhalation and has excellent application prospects in the monitoring of gastric cancer markers.

[0087] The above content is a further detailed description of the present invention in combination with specific preferred embodiments. It cannot be determined that the specific implementation of the present invention is only limited to these descriptions. For those of ordinary skill in the technical field to which the present invention pertains, without departing from the concept of the present invention, several simple deductions or substitutions can still be made, and all should be regarded as belonging to the protection scope of the present invention.

Claims

1. A method for preparing a flexible ammonia gas sensor, characterized in that: The following steps are involved: Ti3C2T x The surface of the self-grown TiO2, Ti3C2T x / TiO2 sensitive material; Obtaining a flexible substrate, and pre-treating the flexible substrate; preparing interdigitated electrodes on the upper surface of the pretreated flexible substrate; The Ti3C2T x / TiO2 sensitive body material is deposited on the upper surface of the interdigital electrodes to obtain a flexible ammonia gas sensor.

2. The method for preparing the flexible ammonia gas sensor according to claim 1, characterized in that: Ti3C2T x Surface self-grown TiO2, including: Ti3C2T x dispersed in a NaBF4 solution having a concentration of 0.1 M to obtain a first mixed solution; adding dilute acid to the first mixed solution, stirring at room temperature until dissolved, to obtain a second mixed solution; The second mixed solution is placed in a high pressure container and subjected to a hydrothermal reaction at a temperature of 150-200°C to partially convert Ti3C2T x In situ conversion to TiO2.

3. The method for preparing the flexible ammonia gas sensor according to claim 2, characterized in that: The Ti3C2T x The ratio of NaBF4 with a concentration of 0.1M is 100mg:12.8~16ml.

4. The method for preparing the flexible ammonia gas sensor according to claim 2, characterized in that: The pH of the second mixed solution is less than or equal to 1.

5. The method for preparing the flexible ammonia gas sensor according to claim 2, characterized in that: The reaction time of the hydrothermal reaction is 9 to 13 hours.

6. The method for preparing a flexible ammonia gas sensor according to claim 1, characterized in that: The flexible substrate is pretreated, comprising: The surface of the flexible substrate is plasma treated.

7. The method for preparing a flexible ammonia gas sensor according to claim 1, characterized in that: The method comprises preparing interdigitated electrodes on the upper surface of the pretreated flexible substrate, comprising: The interdigital electrodes are printed on the upper surface of the pretreated flexible substrate; the interdigital spacing of the interdigital electrodes is 0.08-0.12 cm, and the number of interdigital pairs is 5-7 pairs.

8. The method for preparing a flexible ammonia gas sensor according to claim 1, characterized in that: The material of the flexible substrate includes: PET, PDMS, PI or PEN.

9. The method for preparing a flexible ammonia gas sensor according to claim 1, characterized in that: The Ti3C2T x / TiO2 sensitive body material is deposited on the upper surface of the interdigital electrode, including: The Ti3C2T x / TiO2 sensitive body material is deposited on the upper surface of the interdigital electrodes.

10. A flexible ammonia gas sensor, characterized in that: The method according to any one of claims 1 to 9 comprises: The flexible substrate, interdigitated electrodes and Ti3C2T x / TiO2 sensitive material.

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