Multifunctional gas sensor based on silicon nitride nanostructure and preparation method of multifunctional gas sensor

Abstract

The invention discloses a multifunctional gas sensor based on a silicon nitride nanostructure and a preparation method of the multifunctional gas sensor, and relates to the technical field of multifunctional gas sensors. The sensor is composed of a substrate, an insulating layer, a functional modification sensitive layer and an electrode array, the substrate is made of a silicon wafer or a flexible polyimide material, the insulating layer is made of silicon dioxide / aluminum nitride, and the sensitive layer is made of a silicon nitride nano-film prepared by a plasma enhanced atomic layer deposition technology. The surface of the biosensor is functionally modified by 3-aminopropyltriethoxysilane and is coupled with a biological antibody. The device has the advantages of working at room temperature, low power consumption, high sensitivity and biological-chemical dual-mode detection, and is suitable for rapid detection of chemical gases and pathogens in air.

Description

Technical Field

[0001] The present invention relates to the technical field of multifunctional gas sensors, and particularly relates to a multifunctional gas sensor based on silicon nitride nanostructures and a preparation method thereof. Background Art

[0002] With the acceleration of the industrialization process, the problem of harmful gas leakage has become increasingly prominent. For example, the accidental escape of common gases such as HCl and NH3 in the chemical production process not only causes serious damage to the ecological environment, but also directly threatens the physical health and life safety of on-site workers and surrounding residents. At the same time, the emergence and spread of emerging pathogens have further exacerbated the challenges faced by public safety, and their airborne transmission characteristics have made the need for rapid and real-time monitoring even more urgent.

[0003] When dealing with these threats, traditional gas sensors have exposed many limitations. Traditional sensors mainly made of metal oxides (such as SnO2, WO3) and conductive polymers generally have poor selectivity and are prone to false alarms or missed alarms in complex gas environments. At the same time, these sensors usually need to work at relatively high temperatures, resulting in high power consumption and making it difficult to meet the requirements of portable and long-term monitoring devices. In addition, it is difficult to integrate traditional sensor materials with biological detection functions, and it is impossible to achieve synchronous monitoring of harmful gases and biological pathogens.

[0004] In recent years, it has been found that silicon nitride (SiN X ) thin films have unique advantages and great potential in the field of gas sensing. It has high chemical stability, can maintain stable performance in harsh chemical environments, and is not easily corroded and polluted. Its surface is easily functionalized, and selective recognition of different target gases or biological molecules can be achieved through simple chemical modification, providing new ideas and material bases for the development of multifunctional and highly sensitive gas sensors. However, the current research on silicon nitride-based gas sensors is still in its infancy, and no mature products have been put into practical applications. Especially in complex scenarios with dual threats of harmful gases and biological pathogens, there is a lack of sensor solutions that can monitor in real time and accurately. Summary of the Invention

[0005] The purpose of the present invention is to address the problems existing in the prior art and provide a multifunctional gas sensor based on silicon nitride nanostructures and a preparation method thereof to achieve high-sensitivity, high-selectivity, low-power consumption, and real-time monitoring of harmful gases and biological pathogens.

[0006] To achieve the above object, the technical solution adopted by the present invention is: a multifunctional gas sensor based on silicon nitride nanostructures, the structure of which includes: from bottom to top, a substrate, an insulating layer, a functionalized sensitive layer, and an electrode array;

[0007] Among them, the functionalized sensitive layer is a silicon nitride nanofilmsurface loaded with NH3 + Cl - composite.

[0008] Furthermore, the thickness of the substrate is 0.1 - 1 mm, the thickness of the insulating layer is 100 - 500 nm, the thickness of the functionalized sensitive layer is 10 - 100 nm, the line width of the electrode array is 1 - 10 μm, and the spacing is 5 - 20 μm.

[0009] Furthermore, the substrate can be made of a silicon wafer or a flexible polyimide material. The substrate provides a stable support for the entire sensor, ensuring the stability and reliability of the sensor in different application scenarios.

[0010] Furthermore, the insulating layer can be made of silicon dioxide or aluminum nitride. The insulating layer can effectively prevent the leakage of electricity between the electrodes, improving the electrical performance and measurement accuracy of the sensor.

[0011] The functionalized sensitive layer has a nanoporous structure, which greatly increases the gas adsorption area, enabling the sensor to have higher sensitivity and faster response speed to the target gas.

[0012] Furthermore, the electrode array can efficiently collect and transmit the weak electrical signals generated by gas adsorption.

[0013] Furthermore, the silicon nitride nanofilms are deposited on the insulating layer by plasma-enhanced atomic layer deposition technology.

[0014] Furthermore, the plasma-enhanced atomic layer deposition technology process (PEALD) meets the following conditions:

[0015] Precursors SiH2Cl2 and NH3 plasma are alternately introduced for deposition; the pulse time for introducing the precursor SiH2Cl2 is 0.1 - 1 s, and the interval time is 2 - 5 s; the power of the NH3 plasma is 50 - 200 W, and the pulse time is 1 - 3 s; the deposition cycle is 100 - 200 times.

[0016] Furthermore, the pulse time for introducing the precursor SiH2Cl2 is 0.2 - 0.5 s, and the interval time is 3 - 5 s.

[0017] Furthermore, in the PEALD process, the precursors SiH2Cl2 and NH3 plasmas are alternately introduced. By precisely controlling parameters such as the pulse time, interval time, and power, uniform deposition of the thin film is achieved. By controlling the SiH2Cl2 pulse time and interval time within the ranges of 0.2 - 0.5 s and 3 - 5 s, respectively, the phenomenon of continuous film formation is effectively suppressed, and the formation of nanopores is induced, thereby endowing the functionalized sensitive layer with a unique nanoporous structure, greatly enhancing the gas adsorption performance. In addition, the supply ratio of SiH2Cl2 to NH3 is controlled between 1:3 - 5, and the surface porosity of the deposited silicon nitride nanofilms is within the range of 20% - 60%, further optimizing the gas adsorption and transport performance.

[0018] Furthermore, the deposition process is carried out within a temperature range of 250 - 400 °C. The deposition temperature can not only ensure the high-quality deposition of the thin film but also avoid the adverse effects of excessive temperature on the substrate or the deposited thin film.

[0019] Furthermore, in order to achieve specific detection of chemical industrial gases and pathogens in the air, the surface of the functionalized sensitive layer of the present invention is functionally modified.

[0020] Furthermore, NH3 + Cl - The method for loading the complex on the surface of the silicon nitride nanofilm includes the following steps: immersing the silicon nitride nanofilm in a 0.5 - 1.5 wt% ethanol solution of 3-aminopropyltriethoxysilane and reacting at 60 °C for 1 - 2 hours to form an amine layer; soaking in a 0.1 - 0.2 mol / L aqueous HCl solution for 1 - 2 h to generate a silicon nitride nanofilm loaded with NH3 + Cl - complex.

[0021] Furthermore, biological antibodies can be immobilized on the surface of the silicon nitride nanofilm containing NH3 + Cl - complex by bioconjugation chemistry.

[0022] Furthermore, the biological antibodies are ACE2 receptor aptamers and / or S protein antibodies. The biological antibodies can specifically recognize and bind to the corresponding pathogens, enabling the sensor to have a biological detection function.

[0023] A preparation method of a multifunctional gas sensor based on a silicon nitride nanostructure includes the following key steps:

[0024] Ultrasonically process the substrate for 30 - 40 minutes, deposit the insulating layer material on the surface of the substrate; deposit the functionalized modified sensitive layer on the surface of the insulating layer material; deposit and etch on the surface of the functionalized modified sensitive layer to obtain the electrode array; place the sensor that has completed the above steps in an inert atmosphere, treat it at 200 - 300 °C for 2 - 4 hours, and then perform annealing treatment.

[0025] Furthermore, the deposition method for depositing the insulating layer material on the surface of the substrate is: magnetron sputtering or chemical vapor deposition method.

[0026] Furthermore, the etching is performed by exposing and developing through a photoresist.

[0027] Furthermore, heat to the 200 - 300 °C at a heating rate of 5 - 10 °C / min.

[0028] Furthermore, the photoresist is selected from one or more of the following: AZ photoresist, S1800 photoresist, and SU - 8 photoresist.

[0029] By adopting the above technical solution, a multifunctional gas sensor based on a silicon nitride nanostructure provided by the present invention is used for detecting chemical industrial gases and pathogens in the air.

[0030] Furthermore, the chemical industrial gases include HCl (gas) and NH3; the pathogens include SARS-CoV-2 (novel coronavirus), SARS-CoV-1 (SARS virus), HCoV-NL63 (coronavirus NL63), and PEDV (porcine epidemic diarrhea virus).

[0031] When gases such as HCl and NH3 in the target air come into contact with the functionalized modified sensitive layer of the sensor, the gases will be adsorbed on the surface of the nanoporous structure, causing a change in the resistance of the functionalized modified sensitive layer, which is then detected by the electrode array and converted into a measurable electrical signal, thereby realizing the quantitative detection of the gas concentration.

[0032] Through surface functionalization modification, biological antibodies (such as ACE2 receptor aptamer or S protein antibody) that can specifically recognize biological pathogens are immobilized on the sensor surface. When the virus aerosol in the air comes into contact with the sensor surface, the antibodies on the virus surface will specifically bind to the antibodies on the sensor surface. This binding will also cause a change in the resistance of the functionalized modified sensitive layer. By detecting these changes through the electrode array, qualitative and quantitative detection of biological pathogens can be achieved.

[0033] Compared with the prior art, the beneficial effects of the present invention are:

[0034] 1. High sensitivity and multi-functional integration: Through the design of silicon nitride nanostructures and surface functionalization modification, the sensor not only has high sensitivity and selective detection ability for harmful gases (such as HCl, NH3), but also can specifically recognize biological pathogens (such as SARS-CoV-2), meeting the monitoring needs of multiple threat factors.

[0035] 2. Low power consumption and real-time monitoring: Compared with traditional metal oxide sensors, the present invention can work at room temperature without high-temperature heating, significantly reducing power consumption. At the same time, it can achieve real-time monitoring to promptly detect the leakage of harmful gases or the presence of biological pathogens.

[0036] 3. Good stability and environmental adaptability: Using silicon nitride materials with high chemical stability, the sensor can work stably for a long time in harsh environments, and the preparation process is mature with good repeatability, ensuring the reliability and consistency of the sensor.

[0037] 4. Easy integration and wide application: The sensor has a compact structure design, is easy to integrate with other electronic components, is suitable for making portable or wearable devices, has a wide detection range, can detect a variety of harmful gases and biological pathogens, and has broad application prospects. Specific implementation manners

[0038] The technical solutions of the present invention will be clearly and completely described below in conjunction with the content of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0039] The dichlorosilane involved in the present invention is purchased from: Shanghai Merck Chemical Technology Co., Ltd., ammonia is purchased from: Hubei Jingshan Xinda Industry and Trade Co., Ltd., 3-aminopropyltriethoxysilane, AZ photoresist is purchased from: Shanghai Aladdin Biochemical Technology Co., Ltd., hydrochloric acid is purchased from: Jiangsu Runfeng Synthetic Technology Co., Ltd., ACE2 receptor is purchased from: Shenzhen Jianzhu Technology Co., Ltd., S protein antibody is purchased from: Abcam (Shanghai) Trading Co., Ltd.

[0040] Example 1

[0041] A preparation method of a multi-functional gas sensor based on silicon nitride nanostructures:

[0042] S1. Select a flexible polyimide film (PI) as the substrate and clean it by ultrasonic for 35 minutes; use the chemical vapor deposition method to deposit a 400 nm thick silicon dioxide layer on the substrate surface as the insulating layer;

[0043] The specific experimental steps of the chemical vapor deposition method are as follows: Place the ultrasonically cleaned polyimide film substrate into the reaction chamber, introduce oxygen (O2) for plasma pretreatment (power 100 W, pressure 50 Pa, time 5 minutes) to remove surface contaminants and enhance adhesion; Use a plasma-enhanced chemical vapor deposition (PECVD) system, with silane (SiH4) and nitrous oxide (N2O) as precursor gases and argon (Ar) as the carrier gas, and the gas flow ratio: SiH4:N2O:Ar = 50 sccm:150 sccm:300 sccm; The reaction chamber pressure: 200 Pa, radio frequency power: 200 W, deposition temperature: 250 °C; Turn on the radio frequency power supply to excite the plasma, and make SiH4 react with N2O to generate SiO2; The deposition rate is 20 nm / min, and the total deposition time is 20 minutes. The film thickness is monitored in real time by a quartz crystal microbalance (QCM) until the target thickness of 400 nm is reached.

[0044] S2. Then, use the plasma-enhanced atomic layer deposition technique (PEALD) to deposit a silicon nitride nanometer film on the surface of the insulating layer. The specific process parameters are as follows:

[0045] ① The pulse time of the precursor SiH2Cl2 is 0.2 s, and the interval time is 1 s;

[0046] ② The power of the NH3 plasma is 150 W, and the pulse time is 2 s;

[0047] ③ The deposition temperature is 300 °C;

[0048] ④ The number of cycles is 150 times;

[0049] The porosity is stabilized in the range of 40% - 60%, the thickness is 50 nm, and the pore diameter is 25 nm.

[0050] S3. Functionalize the silicon nitride nanometer film: Immerse the silicon nitride nanometer film in a 0.1% ethanol solution of 3-aminopropyltriethoxysilane (APTES), react at 60 °C for 2 hours to form a uniform amine layer, and soak in a 0.2 mol / L HCl aqueous solution for 2 h to adsorb Cl - , generating a silicon nitride-NH3 + Cl - complex to form a functionalized sensitive layer.

[0051] S4. Deposit 10 μm of gold on the surface of the functionalized sensitive layer; apply AZ photoresist (thickness 1.2 μm), expose it for 4 h at 345 nm and then develop it to obtain the electrode array; place the sensor that has completed the above steps in an inert atmosphere, heat it to 200 °C at a heating rate of 10 °C / min, and hold for 4 hours for annealing treatment, thus obtaining a multifunctional gas sensor based on silicon nitride nanostructures;

[0052] The surface deposition is carried out by magnetron sputtering, and the specific experimental steps are as follows: The specific process parameters are as follows: Use a high-purity gold target (purity ≥ 99.99%), and the substrate temperature is at room temperature (to avoid damaging the sensitive layer at high temperatures); The base vacuum of the sputtering chamber: ≤ 5×10 -6 Torr; Sputtering gas: argon (Ar), flow rate 50 sccm, working pressure 5 mTorr; Sputtering power: DC power 100 W, deposition rate about 0.5 nm / s; Total deposition time: about 5.5 hours (10 μm = 10,000 nm, deposition rate 0.5 nm / s → 20,000 seconds ≈ 5.5 hours).

[0053] Example 2

[0054] A preparation method of a multifunctional gas sensor based on silicon nitride nanostructures:

[0055] S1. Select a flexible polyimide film (PI) as the substrate and clean it by ultrasonic for 35 minutes; Adopt the chemical vapor deposition method to deposit a 400 nm thick silicon dioxide layer on the substrate surface as the insulating layer. The specific experimental steps of the chemical vapor deposition method are the same as those in Example 1.

[0056] S2. Use plasma-enhanced atomic layer deposition technology (PEALD) to deposit a silicon nitride nanofilm on the surface of the insulating layer. The specific process parameters are as follows:

[0057] ① The pulse time of the precursor SiH2Cl2 is 0.2 s, and the interval time is 1 s;

[0058] ② The power of NH3 plasma is 150 W, and the pulse time is 2 s;

[0059] ③ The deposition temperature is 300 °C;

[0060] ④ The number of cycles is 150 times;

[0061] The porosity is stabilized in the range of 40% - 60%, the thickness is 50 nm, and the pore diameter is 25 nm.

[0062] S3. Functional modification of silicon nitride nanofilms: Immerse the silicon nitride nanofilms in a 0.1% ethanol solution of 3-aminopropyltriethoxysilane (APTES) and react at 60 °C for 2 hours to form a uniform amine layer. Immerse it in a 0.2 mol / L HCl aqueous solution for 2 h to adsorb Cl - , generating silicon nitride-NH3 + Cl - complex. On the surface of the silicon nitride-NH3 + Cl - complex, fix the bio-antibody ACE2 receptor aptamer and S protein antibody on its surface through EDC / NHS chemical coupling reaction to form a functionally modified sensitive layer.

[0063] S4. Deposit 10 μm of gold on the surface of the functionally modified sensitive layer, apply AZ photoresist, expose it at 345 nm for 4 h and then develop it to obtain the electrode array; Place the sensor that has completed the above steps in an inert atmosphere, heat it to 200 °C at a heating rate of 10 °C / min, and keep it for 4 hours for annealing treatment, thus obtaining a multifunctional gas sensor based on silicon nitride nanostructures, where the specific experimental steps of the surface deposition are the same as those in Example 1.

[0064] Performance test:

[0065] 1. HCl detection: Expose the multifunctional gas sensors based on silicon nitride nanostructures prepared in Example 1 and Example 2 to a 10 ppm HCl gas environment, and record the initial resistance value R0 of the sensor when it is not in contact with the gas and the resistance change amount ΔR of the sensor after it is in contact with the gas. The larger ΔR / R0 is, the more sensitive the sensor is to the gas. Record the time required for the resistance value to recover to 10% of the initial value as the recovery time. The shorter the recovery time is, the better the recovery performance of the sensor is, and it can adapt to environmental changes faster.

[0066] 2. SARS-CoV-2 pseudovirus particle detection: Expose the multifunctional gas sensor based on silicon nitride nanostructures prepared in Example 2 to an aerosol containing SARS-CoV-2 pseudovirus particles, with a concentration gradient of 10 1 -10 5 PFU / mL, and evaluate the detection performance of the sensor by measuring the impedance change (ΔZ).

[0067] 3. Sensitivity determination after 500 hours of continuous operation: Before the sensor starts working, record its initial sensitivity (ΔA / A0). Let the sensor work continuously for 500 hours in a specific gas environment. During the working process, regularly record the response value of the sensor (ΔA / A0). After 500 hours, measure the sensitivity of the sensor again and compare it with the initial sensitivity to calculate the percentage of sensitivity decay. The formula for calculating the percentage of sensitivity decay is:

[0068] .

[0069] 4. The performance test results are as follows:

[0070] The response value of a multifunctional gas sensor based on a silicon nitride nanostructure prepared in Example 1 to 10 ppm HCl is ΔR / R0 = 85%, the recovery time is < 30 s, and the sensitivity decay is < 5% after continuous operation for 500 hours.

[0071] The response value of a multifunctional gas sensor based on a silicon nitride nanostructure prepared in Example 2 to 10 ppm HCl is ΔR / R0 = 80%, the recovery time is < 30 s, and the sensitivity decay is < 4% after continuous operation for 500 hours.

[0072] According to the detection results of a multifunctional gas sensor prepared in Example 2, it can be seen that the concentration of SARS-CoV-2 pseudovirus particles has a linear relationship with the impedance change (ΔZ), and the linear range is 10 2 -10 5 PFU / mL, and the detection limit is 10 2 PFU / mL. At 10 2 PFU / mL, the ΔZ value is ΔZ0; at 10 5 PFU / mL, the ΔZ value is ΔZ max , and the change range of ΔZ is ΔZ max -ΔZ0. After continuous operation for 500 hours, the sensitivity decay of the sensor is < 5%.

[0073] The multifunctional gas sensor based on a silicon nitride nanostructure of the present invention exhibits excellent performance and technical effects. In the detection of gases and biological pathogens, it shows high sensitivity, fast response, and good stability. The realization of these technical effects is mainly attributed to the functionalized modification of the sensitive layer, making the sensor have significant advantages and broad application prospects in the field of harmful gas and biological pathogen detection.

[0074] Although embodiments of the present invention have been shown and described, those of ordinary skill in the art will appreciate that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A multifunctional gas sensor based on silicon nitride nanostructure, characterized in that: The structure of the multifunctional gas sensor includes: from bottom to top, this is the base, the insulating layer, the functional modified sensitive layer, and the electrode array; Wherein, the functional modified sensitive layer is surface loaded with NH3 + Cl - Silicon nitride nanofilms of composites.

2. A multifunctional gas sensor based on silicon nitride nanostructure according to claim 1, characterized in that: The silicon nitride nanofilm is deposited on the insulating layer by plasma enhanced atomic layer deposition technology.

3. A multifunctional gas sensor based on silicon nitride nanostructure according to claim 2, characterized in that: The plasma enhanced atomic layer deposition technology process meets the following conditions: Alternately introduce precursor SiH2Cl2 and NH3 plasma for deposition; the pulse time of the precursor SiH2Cl2 is 0.1-1 s, and the interval time is 2-5 s; the power of the NH3 plasma is 50-200 W, and the pulse time is 1-3 s; Furthermore, the precursor SiH2Cl2 is introduced with a pulse time of 0.2-0.5 s and an interval time of 3-5 s.

4. A multifunctional gas sensor based on silicon nitride nanostructure according to claim 3, characterized in that: The volume supply ratio of the precursor SiH2Cl2 to NH3 is 1:(3-5), and the surface porosity of the deposited silicon nitride nanofilm is 20%-60%.

5. The multifunctional gas sensor based on silicon nitride nanostructure according to claim 3, characterized in that: The deposition is carried out at 250-400°C.

6. A multifunctional gas sensor based on silicon nitride nanostructure according to claims 1-5, characterized in that: NH3 is loaded on the surface of the silicon nitride nanofilm + Cl - The composite method comprises the following steps: immersing the silicon nitride nanofilm in a 0.5-1.5wt% 3-aminopropyltriethoxysilane ethanol solution, reacting at 60°C for 1-2 hours to form an amine-based layer; immersing in a 0.1-0.2mol / L HCl aqueous solution for 1-2 hours to generate NH3 + Cl - The composite is loaded on the silicon nitride nano film.

7. The multifunctional gas sensor based on silicon nitride nanostructure according to claim 6, characterized in that: The NH3 can be loaded + Cl - The biological antibodies are fixed on the surface of the silicon nitride nanofilm of the composite.

8. The multifunctional gas sensor based on silicon nitride nanostructure according to claim 1, characterized in that: The thickness of the substrate is 0.1-1 mm, the thickness of the insulating layer is 100-500 nm, the thickness of the functional modified sensitive layer is 10-100 nm, the line width of the electrode array is 1-10 μm and the spacing is 5-20 μm.

9. A method for preparing a multifunctional gas sensor based on silicon nitride nanostructure according to any one of claims 1 to 8, characterized in that: The following steps are involved: Ultrasonic treatment is performed on the substrate for 30-40 minutes to deposit the insulating layer material on the substrate surface; the functional modified sensitive layer is deposited on the insulating layer material surface; and deposition and etching are performed on the surface of the functional modified sensitive layer to obtain the electrode array; The sensor after the above steps is placed in an inert atmosphere, treated at 200-300° C. for 2-4 hours, and then annealed.

10. Use of a multifunctional gas sensor based on silicon nitride nanostructure according to any one of claims 1 to 8 in detecting chemical gases and pathogens in the air.