A multifunctional gas sensor based on silicon nitride nanostructure and a preparation method thereof

Abstract

This invention discloses a multifunctional gas sensor based on silicon nitride nanostructures and its fabrication method, belonging to the field of multifunctional gas sensor technology. The sensor consists of a substrate, an insulating layer, a functionalized sensitive layer, and an electrode array. The substrate is made of silicon wafer or flexible polyimide material, the insulating layer is silicon dioxide / aluminum nitride, and the sensitive layer is a silicon nitride nanofilm prepared by plasma-enhanced atomic layer deposition (PEALD), with its surface functionalized by 3-aminopropyltriethoxysilane and coupled with a biological antibody. This invention combines the advantages of room temperature operation, low power consumption, high sensitivity, and bio-chemical dual-mode detection, making it suitable for rapid detection of chemical gases and pathogens in the air.

Description

Technical Field

[0001] This invention relates to the field of multifunctional gas sensor technology, specifically to a multifunctional gas sensor based on silicon nitride nanostructures and its fabrication method. Background Technology

[0002] With the acceleration of industrialization, the problem of hazardous gas leaks has become increasingly prominent. Accidental releases of gases such as HCl and NH3, commonly found in chemical production processes, not only cause serious damage to the ecological environment but also directly threaten the health and safety of on-site workers and surrounding residents. At the same time, the emergence and spread of new pathogens further exacerbate the challenges to public safety, and their airborne transmission characteristics make rapid, real-time monitoring increasingly urgent.

[0003] Traditional gas sensors have revealed numerous limitations in addressing these threats. Sensors primarily composed of metal oxides (such as SnO2 and WO3) and conductive polymers generally suffer from poor selectivity, making them prone to false alarms or missed alarms in complex gas environments. Furthermore, these sensors typically operate at high temperatures, resulting in high power consumption, which is insufficient for portable, long-term monitoring devices. In addition, integrating traditional sensor materials with biological detection functions is challenging, making simultaneous monitoring of harmful gases and biological pathogens impossible.

[0004] Recent studies have found that silicon nitrides (SiN) X Thin films possess unique advantages and enormous potential in the field of gas sensing. They exhibit high chemical stability, maintaining performance stability even in harsh chemical environments and are not easily corroded or contaminated. Their surfaces are easily functionalized, allowing for selective recognition of different target gases or biomolecules through simple chemical modifications, providing new ideas and material foundations for developing multifunctional, highly sensitive gas sensors. However, research on silicon nitride-based gas sensors is still in its early stages, with no mature products yet deployed in practical applications. This is particularly true in complex scenarios posing dual threats of harmful gases and biological pathogens, where a sensor solution capable of real-time and accurate monitoring is lacking. Summary of the Invention

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

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

[0007] The functionalized modified sensitive layer is a surface-loaded NH3 layer. + Cl - The composite silicon nitride nanofilm.

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

[0009] Furthermore, the substrate can be made of silicon wafer or flexible polyimide material. The substrate provides 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. This insulating layer effectively prevents leakage between electrodes, improving the electrical performance and measurement accuracy of the sensor.

[0011] The functionalized modified 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 nanofilm is deposited onto the insulating layer using plasma-enhanced atomic layer deposition (PEALD).

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

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

[0016] Furthermore, the pulse duration of the SiH2Cl2 precursor is 0.2-0.5 s and the interval is 3-5 s.

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

[0018] Furthermore, the deposition process is carried out within a temperature range of 250-400°C. This deposition temperature ensures high-quality film deposition while avoiding adverse effects of excessively high temperatures on the substrate or the deposited film.

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

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

[0021] Furthermore, NH3 can be included on the surface. + Cl - Biological antibodies were immobilized on the surface of the silicon nitride nanofilm of the complex via a bio-coupling chemical method.

[0022] Furthermore, the biological antibody is an ACE2 receptor aptamer and / or an S protein antibody. This biological antibody can specifically recognize and bind to the corresponding pathogen, enabling the sensor to possess biological detection capabilities.

[0023] A method for fabricating a multifunctional gas sensor based on silicon nitride nanostructures includes the following key steps:

[0024] The substrate is ultrasonically treated for 30-40 minutes to deposit the insulating layer material on the substrate surface; the functionalized modified sensitive layer is deposited on the surface of the insulating layer material; the surface of the functionalized modified sensitive layer is deposited and etched to obtain the electrode array; the sensor that has completed the above steps is placed in an inert atmosphere and treated at 200-300℃ for 2-4 hours, followed by annealing.

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

[0026] Furthermore, the etching is performed by exposure to photoresist followed by development.

[0027] Further, the temperature is increased to 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, the present invention provides a multifunctional gas sensor based on silicon nitride nanostructures for the detection of chemical gases and pathogens in the air.

[0030] Furthermore, the chemical 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 (swine 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 are adsorbed on the surface of the nanoporous structure, causing a change in the resistance of the functionalized modified sensitive layer. This change is then detected by the electrode array and converted into a measurable electrical signal, thereby enabling quantitative detection of gas concentration.

[0032] Through surface functionalization, biological antibodies (such as ACE2 receptor aptamers or S protein antibodies) capable of specifically recognizing biological pathogens are immobilized on the sensor surface. When viral aerosols in the air come into contact with the sensor surface, the antibodies on the viral surface specifically bind to the antibodies on the sensor surface. This binding also causes a change in the resistance of the functionalized sensitive layer. By detecting these changes through an 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 multifunctional integration: Through silicon nitride nanostructure design and surface functionalization modification, the sensor not only has high sensitivity and selective detection capability for harmful gases (such as HCl and NH3), but also specifically identifies 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, this invention can operate at room temperature without high-temperature heating, which significantly reduces power consumption. At the same time, it can achieve real-time monitoring and timely detect the leakage of harmful gases or the presence of biological pathogens.

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

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

[0038] The technical solution of the present invention will be clearly and completely described below in conjunction with the inventive content. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

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

[0040] Example 1

[0041] A method for fabricating a multifunctional gas sensor based on silicon nitride nanostructures:

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

[0043] The specific experimental steps of the chemical vapor deposition method are as follows: The ultrasonically cleaned polyimide film substrate is placed in the reaction chamber, and oxygen (O2) is introduced for plasma pretreatment (power 100 W, pressure 50 Pa, time 5 minutes) to remove surface contaminants and enhance adhesion. A plasma-enhanced chemical vapor deposition (PECVD) system is used, with silane (SiH4) and nitrous oxide (N2O) as precursor gases and argon (Ar) as the carrier gas. The gas flow ratio is: SiH4:N2O:Ar = 50 sccm:150 sccm:300 sccm. The reaction chamber pressure is 200 Pa, the radio frequency power is 200 W, and the deposition temperature is 250℃. The radio frequency power is turned on to excite the plasma, causing SiH4 and N2O to react and 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 using a quartz crystal microbalance (QCM) until the target thickness of 400 nm is reached.

[0044] S2. Then, using plasma-enhanced atomic layer deposition (PEALD) technology, a silicon nitride nanofilm is deposited on the surface of the insulating layer. The specific process parameters are as follows:

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

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

[0047] ③The deposition temperature is 300℃;

[0048] ④ The number of cycles is 150;

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

[0050] S3. Functionalized modification of silicon nitride nanofilms: Silicon nitride nanofilms were immersed in a 0.1% solution of 3-aminopropyltriethoxysilane (APTES) in ethanol and reacted at 60°C for 2 hours to form a uniform amine substrate. The substrate was then soaked in a 0.2 mol / L HCl aqueous solution for 2 hours to adsorb Cl. - The silicon nitride -NH3 is formed. + Cl - The complex forms a functionalized modified sensitive layer.

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

[0052] The surface deposition was performed using magnetron sputtering, and the specific experimental steps are as follows: Specific process parameters are as follows: high-purity gold target material (purity ≥ 99.99%) was used; the substrate temperature was room temperature (to avoid high-temperature damage to the sensitive layer); the base vacuum of the sputtering chamber was ≤ 5 × 10⁻⁶. -6 Torr; Sputtering gas: Argon (Ar), flow rate 50 sccm, working pressure 5 mTorr; Sputtering power: DC power 100 W, deposition rate approximately 0.5 nm / s; Total deposition time: approximately 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 method for fabricating 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 cleaning for 35 minutes; use chemical vapor deposition to deposit a 400 nm silicon dioxide layer on the substrate surface as an insulating layer. The specific experimental steps of the chemical vapor deposition method are the same as in Example 1.

[0056] S2. A silicon nitride nanofilm is deposited on the surface of the insulating layer using plasma-enhanced atomic layer deposition (PEALD) technology. The specific process parameters are as follows:

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

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

[0059] ③The deposition temperature is 300℃;

[0060] ④ The number of cycles is 150;

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

[0062] S3. Functionalized modification of silicon nitride nanofilms: Silicon nitride nanofilms were immersed in a 0.1% solution of 3-aminopropyltriethoxysilane (APTES) in ethanol and reacted at 60°C for 2 hours to form a uniform amine substrate. The substrate was then soaked in a 0.2 mol / L HCl aqueous solution for 2 hours to adsorb Cl. - The silicon nitride -NH3 is formed. + Cl - Complex, in silicon nitride-NH3 + Cl - The surface of the complex is immobilized with the biological antibody ACE2 receptor aptamer and S protein antibody via an EDC / NHS chemical coupling reaction, forming a functionalized modified sensitive layer.

[0063] S4. Deposit 10 μm of gold on the surface of the functionalized modified sensitive layer, apply AZ photoresist, expose at 345 nm for 4 h and then develop 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 to obtain a multifunctional gas sensor based on silicon nitride nanostructure, wherein the specific experimental steps of surface deposition are the same as in Example 1.

[0064] Performance testing:

[0065] 1. HCl Detection: A multifunctional gas sensor based on a silicon nitride nanostructure prepared in Examples 1 and 2 was exposed to a 10 ppm HCl gas environment. The initial resistance value R0 of the sensor before contact with the gas and the change in resistance ΔR after contact with the gas were recorded. The larger the ΔR / R0, the more sensitive the sensor is to the gas. The time required for the resistance value to recover to 10% of the initial value was recorded as the recovery time. The shorter the recovery time, the better the recovery performance of the sensor and the faster it can adapt to environmental changes.

[0066] 2. Detection of SARS-CoV-2 pseudovirus particles: A multifunctional gas sensor based on silicon nitride nanostructures prepared in Example 2 was exposed to an aerosol containing SARS-CoV-2 pseudovirus particles at a concentration gradient of 10. 1 -10 5 PFU / mL, the sensor's detection performance is evaluated by measuring impedance change (ΔZ).

[0067] 3. Sensitivity Measurement After 500 Hours of Continuous Operation: Before the sensor begins operation, record its initial sensitivity (ΔA / A0). Allow the sensor to operate continuously for 500 hours in a specific gas environment. During operation, periodically record the sensor's response value (ΔA / A0). After 500 hours, measure the sensor's sensitivity 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 multifunctional gas sensor based on silicon nitride nanostructure prepared in Example 1 has a response value of ΔR / R0=85% to 10 ppm HCl, a recovery time of <30 seconds, and a sensitivity decay of <5% after 500 hours of continuous operation.

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

[0072] According to the detection results of a multifunctional gas sensor prepared in Example 2, the concentration of SARS-CoV-2 pseudovirus particles is linearly related to the impedance change (ΔZ), with a linear range of 10. 2 -10 5 PFU / mL, detection limit is 10 2 PFU / mL. At 10 2 At PFU / mL, the ΔZ value is ΔZ0; at 10 5 At PFU / mL, the ΔZ value is ΔZ max The range of ΔZ is ΔZ max -ΔZ0. After 500 hours of continuous operation, the sensor's sensitivity decreases by <5%.

[0073] The multifunctional gas sensor based on silicon nitride nanostructures of this invention exhibits superior performance and technical advantages. In the detection of gases and biological pathogens, it demonstrates high sensitivity, rapid response, and good stability. These technical advantages are primarily attributed to the functionalized modified sensitive layer, giving the sensor significant advantages and broad application prospects in the detection of harmful gases and biological pathogens.

[0074] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A multifunctional gas sensor based on silicon nitride nanostructures, characterized in that, The structure of the multifunctional gas sensor includes, from bottom to top: a substrate, an insulating layer, a functionalized modified sensitive layer, and an electrode array; The functionalized modified sensitive layer is a surface-loaded NH3 layer. + Cl - A silicon nitride nanofilm of a composite material is deposited onto an insulating layer using plasma-enhanced atomic layer deposition (PEALD). The PEALD process meets the following conditions: alternating introduction of precursor plasmas SiH₂Cl₂ and NH₃ for deposition; the pulse duration of the SiH₂Cl₂ precursor is 0.1-1 s, with an interval of 2-5 s; the power of the NH₃ plasma is 50-200 W, with a pulse duration of 1-3 s. NH3 is loaded on the surface of the silicon nitride nanofilm + Cl - The method for constructing the composite includes the following steps: immersing the silicon nitride nanofilm in a 0.5-1.5 wt% 3-aminopropyltriethoxysilane ethanol solution and reacting at 60°C for 1-2 hours to form an amine substrate; then soaking it in a 0.1-0.2 mol / L HCl aqueous solution for 1-2 hours to generate NH3. + Cl - The composite is loaded onto the silicon nitride nanofilm.

2. The multifunctional gas sensor based on silicon nitride nanostructures as described in claim 1, characterized in that, The pulse duration of the precursor SiH2Cl2 was 0.2-0.5 s, and the interval was 3-5 s.

3. A multifunctional gas sensor based on silicon nitride nanostructures as described in claim 2, 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%.

4. A multifunctional gas sensor based on silicon nitride nanostructures as described in claim 3, characterized in that, The deposition was carried out at 250-400°C.

5. The multifunctional gas sensor based on silicon nitride nanostructures according to claim 1, characterized in that, The NH3 load can be used + Cl - Biological antibodies are immobilized on the surface of a silicon nitride nanofilm of the complex.

6. The multifunctional gas sensor based on silicon nitride nanostructures according to claim 1, characterized in that, The substrate has a thickness of 0.1-1 mm, the insulating layer has a thickness of 100-500 nm, the functionalized modified sensitive layer has a thickness of 10-100 nm, and the electrode array has a linewidth of 1-10 μm and a spacing of 5-20 μm.

7. A method for fabricating a multifunctional gas sensor based on a silicon nitride nanostructure as described in any one of claims 1-6, characterized in that, Includes the following steps: The substrate is ultrasonically treated for 30-40 minutes to deposit the insulating layer material on the substrate surface; the functionalized modified sensitive layer is deposited on the surface of the insulating layer material; the surface of the functionalized modified sensitive layer is deposited and etched to obtain the electrode array; The sensor, after completing the above steps, is placed in an inert atmosphere and treated at 200-300°C for 2-4 hours, followed by annealing.

8. An application of a multifunctional gas sensor based on silicon nitride nanostructures as described in any one of claims 1-6 for detecting NH3 and HCl gases in the air.

9. An application of a multifunctional gas sensor based on a silicon nitride nanostructure as described in any one of claims 1-6 for detecting pathogens in the air, characterized in that, NH3 is contained on the surface + Cl - Biological antibodies were immobilized on the surface of the silicon nitride nanofilm of the complex via a bio-coupling chemical method.