Molybdenum disulfide nanopore chip and preparation method and application thereof

Abstract

The invention discloses a molybdenum disulfide nanopore chip as well as a preparation method and application thereof, and belongs to the technical field of environmental pollutant detection. The preparation method comprises the following steps: firstly, preparing a PMMA-MoS2 film, and then transferring the PMMA-MoS2 film to the surface of silicon nitride; a helium ion beam etching technology and a scanning electron microscope technology are combined to form the nanopores in the molybdenum disulfide film. The sensor can be used for efficiently detecting a copper (Cu)-thiocyanate compound in an environment, has the characteristics of high sensitivity, quick response and good selectivity, and is suitable for the fields of environment monitoring, pollutant detection and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of environmental pollutant detection, and more specifically relates to a molybdenum disulfide nanopore chip and a preparation method and application thereof. Background Art

[0002] Copper (Cu)-thiocyanate complexes are a common type of heavy metal pollutants in the environment, widely present in industrial wastewater, mining drainage, and agricultural and chemical industries. Such complexes have serious impacts on aquatic ecosystems, soil quality, and human health. Especially in the process of metallurgy, mining, and pesticide production, the complexes formed by the reaction of copper (Cu) and thiocyanate often have a long retention time in the environment, leading to long-term pollution and increasing the difficulty of water source management. Therefore, the detection of copper (Cu)-thiocyanate complexes is particularly important.

[0003] Traditional copper ion detection methods, such as chemical analysis, electrochemical method and spectroscopy, can provide certain detection capabilities, but they often require complex sample pretreatment steps and have problems such as poor detection sensitivity and selectivity. Therefore, it is of great practical significance to develop a highly sensitive, rapid, real-time and label-free detection method. Summary of the invention

[0004] The purpose of the present invention is to provide a molybdenum disulfide nanopore chip and its preparation method and application to solve the problems existing in the above-mentioned prior art. The present invention first prepares a PMMA-MoS2 film and then transfers it to a silicon nitride surface. Nanopores are formed on the molybdenum disulfide film by combining helium ion beam etching (HIV) technology and scanning electron microscopy (SEM) technology. The sensor assembled with this chip can be used for efficient detection of copper (Cu)-thiocyanate complexes in the environment, and has the characteristics of high sensitivity, rapid response and good selectivity, and is suitable for environmental monitoring and pollutant detection.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] One of the technical solutions of the present invention is to provide a method for preparing a molybdenum disulfide nanopore chip, comprising the following steps:

[0007] Firstly, a MoS2 layer is deposited on the surface of the substrate, and then a polymethyl methacrylate solution is coated on the surface of the MoS2 layer, and after curing, a substrate with a PMMA-MoS2 film attached is obtained;

[0008] The substrate with the PMMA-MoS2 film attached is immersed in an alkaline solution to separate the PMMA-MoS2 film from the substrate;

[0009] The PMMA-MoS2 film is transferred to a silicon nitride chip, and then annealed and PMMA removed to obtain a molybdenum disulfide chip;

[0010] The molybdenum disulfide chip is subjected to nanopore processing and size control to obtain the molybdenum disulfide nanopore chip.

[0011] The present invention first prepares a PMMA-MoS2 film and then transfers it to the silicon nitride surface. Nanopores are formed on the molybdenum disulfide film by combining helium ion beam etching (HIV) technology and scanning electron microscopy (SEM) technology. Among them, PMMA is arranged on the surface of the MoS2 film, and PMMA serves as a transfer medium to ensure that the PMMA-MoS2 film is smoothly transferred to the silicon nitride surface; in addition, PMMA has good flexibility and mechanical strength, and can be used as a protective layer of the MoS2 film to prevent cracks or damage to the MoS2 film during the preparation process. Helium ion beam etching technology has extremely high spatial resolution and etching accuracy, and can accurately carve out the required hole shape and size at the nanoscale; and scanning electron microscopy technology is not only used to monitor the etching process in real time to ensure that the formation of nanopores meets the design requirements, but also can perform high-resolution imaging and characterization of the nanopore structure, and can also participate in the processing process of the nanopore. The present invention further improves the sensitivity, responsiveness and selectivity of the sensor by combining helium ion beam etching (HIV) technology and scanning electron microscopy (SEM) technology.

[0012] Preferably, the thickness of the MoS2 layer is 1 to 3 nm; the coating amount is 120 to 400 g / m 2 The mass fraction of the polymethyl methacrylate solution is 2 to 4%; the curing temperature is 120 to 150°C and the curing time is 5 to 10 minutes.

[0013] Preferably, the alkali solution includes sodium hydroxide; the concentration of the alkali solution is 2 mol / L; and the soaking time is 2 to 3 hours.

[0014] Preferably, the silicon nitride chip includes a silicon substrate and a silicon nitride layer; the annealing temperature is 100-120°C and the time is 1-2 hours; the PMMA removal includes: placing the annealed product in acetone and immersing it repeatedly for 3 times, the time of the first and second immersions is independently 30-60 minutes, and the time of the third immersion is 8 hours.

[0015] Furthermore, after PMMA is removed, the process also includes the steps of washing and drying the product in sequence.

[0016] Preferably, nanopore processing and size control are performed on the MoS2 chip by helium ion beam etching (HIV); the parameters of the helium ion beam etching (HIV) include: aperture size of 5 μm, ion beam current of 3 pA, circular pattern, pattern diameter of 30 nm, dwell time of 1000 μs, pixel size of 1 nm 2 , ion dose is 20~60nC / μm 2 , the interval is 80nm, and the formed nanopore is elliptical with a major-minor axis ratio of 1.05 to 1.15.

[0017] The present invention adopts the step of processing the molybdenum disulfide chip with an aperture size of 5 μm and an ion beam flow of 3 pA, which can avoid the damage of the MoS2 film by direct helium ion beam etching and ensure that the nanopore size meets the requirements.

[0018] In the present invention, the aperture size of 5 μm helps to focus the ion beam and reduce ion scattering, thereby improving the spatial resolution and accuracy of etching; the ion beam current of 3 pA ensures a moderate etching rate while avoiding damage to the MoS2 film caused by excessive ion current; the circular pattern and the pattern diameter of 30 nm ensure that the shape and size of the nanopores meet the design requirements, providing a consistent pore size to achieve uniform sensing performance; the dwell time of 1000 μs controls the etching depth of each nanopore, ensuring that the depth of the pore size is consistent with expectations; the pixel size is 1 nm 2 Improved the resolution of the etching process, making the edge of the nanopore smoother and more precise; ion dose is 20-60nC / μm 2 By adjusting the dosage range, the energy input of etching is optimized to ensure the reliability and consistency of nanopore formation; the spacing of 80nm ensures the uniform distribution of nanopores in the film and prevents mutual interference between pores; finally, the nanopores are elliptical, and the ratio of the major axis to the minor axis is 1.05 to 1.15, which ensures the stability and repeatability of the aperture shape and helps to improve the sensor's selective recognition of specific molecules. Through the precise regulation of the above parameters, the present invention can achieve a highly controllable and uniformly distributed nanopore structure on the MoS2 film, thereby significantly improving the overall performance of the molybdenum disulfide chip and meeting the detection requirements of high sensitivity and high selectivity.

[0019] Preferably, the molybdenum disulfide chip is subjected to nanopore processing and size control by a scanning electron microscope (SEM); the parameters of the scanning electron microscope (SEM) include: an acceleration voltage of 0.5 to 5 kV, a processing height of 8 mm, a magnification of 100,000 times, a scanning range of 1300 nm × 950 nm, a current of 2 μA, and a duration of 3 s for each irradiation.

[0020] In the present invention, the acceleration voltage of 0.5-5kV can optimize the penetration depth and resolution of the electron beam and avoid excessive damage to the MoS2 film; the processing height of 8mm ensures the accurate focusing of the electron beam on the sample surface and improves the fineness and consistency of etching; the magnification of 100,000 times helps to achieve high-precision positioning and fine etching of the nanopores, ensuring that the aperture and shape meet the design requirements; the scanning range of 1300nm×950nm covers the required etching area, ensuring that the distribution and density of the nanopores are uniform and meet the performance requirements of the sensor; the current of 2μA provides appropriate electron beam intensity to achieve an efficient etching process, while controlling the energy input to prevent overheating or damage to the film; the duration of each irradiation is 3s to ensure the consistency of the etching depth and shape of each nanopore, avoiding aperture differences caused by uneven irradiation time.

[0021] Furthermore, the present invention performs nanopore processing and size control on the molybdenum disulfide chip through helium ion beam etching (HIV) and scanning electron microscopy (SEM), so that the nanopore diameter of the prepared molybdenum disulfide nanopore chip is 30-45nm.

[0022] Preferably, the method for preparing the molybdenum disulfide nanopore chip further comprises depositing carbon at one end away from PMMA using chemical vapor deposition (CVD) technology to form a uniform and dense carbon layer;

[0023] The specific parameters are as follows: the parameter settings of carbon deposition include deposition temperature of 500-700°C, deposition time of 20-40min, gas flow rate of 40-60sccm, deposition rate of 0.1-0.3nm / s, gas pressure of 0.8-1.2Torr, and acetylene gas is used as the carbon source.

[0024] The setting range of these parameters ensures high-quality deposition of the carbon layer, providing excellent conductivity and mechanical strength. The conductivity, mechanical stability and chemical stability of the MoS2 nanopore chip are significantly improved. At the same time, the bottoming design on the back of the chip further enhances the structural support of the chip, ensuring its long-term stability and high-efficiency performance in practical applications.

[0025] Temperature (500-700°C) control: Within this temperature range, carbon atoms can effectively diffuse and form a high-quality carbon layer on the MoS2 film. Higher temperatures help improve the crystallization quality and density of the carbon layer, while lower temperatures help control the deposition rate and avoid defects caused by too fast carbon deposition.

[0026] The time (20-40 minutes) is to control the thickness: by adjusting the deposition time, the thickness of the carbon layer can be precisely controlled. Longer deposition time helps to form a thicker and denser carbon layer, enhancing mechanical strength and conductivity; shorter time is suitable for application scenarios that require a thinner carbon layer.

[0027] Gas (acetylene gas, gas flow rate is 40-60 sccm) supply stability: Appropriate gas flow rate ensures a stable supply of acetylene gas, maintains the uniformity of the reaction atmosphere during the deposition process, and avoids adverse effects of gas concentration fluctuations on the quality of the carbon layer.

[0028] Deposition rate (0.1-0.3 nm / s) ensures layer uniformity: Controlling the deposition rate helps achieve uniform growth of the carbon layer, avoiding rough surfaces caused by too fast deposition or inefficient processes caused by too slow deposition.

[0029] Gas pressure (0.8-1.2 Torr) is an optimization of the deposition environment: appropriate gas pressure helps to control the particle collision frequency in the reaction atmosphere, optimize the migration path of carbon atoms, and improve the density and crystal quality of the carbon layer.

[0030] The second technical solution of the present invention: providing a molybdenum disulfide nanopore chip prepared by the above preparation method.

[0031] The third technical solution of the present invention: provides the application of the molybdenum disulfide nanopore chip in the detection of copper-thiocyanate complexes.

[0032] The fourth technical solution of the present invention: provides a method for detecting a copper-thiocyanate complex that improves the sensitivity, selectivity and real-time performance of detection, comprising the following steps: detecting the copper-thiocyanate complex using the molybdenum disulfide nanopore chip.

[0033] The present invention discloses the following technical effects:

[0034] 1. High sensitivity and precise control:

[0035] The present invention uses helium ion beam etching (HIV) and scanning electron microscopy (SEM) to process nanopores and size control on a molybdenum disulfide chip, so that the size of the nanopore can be accurately controlled between 30 and 45 nm, meeting the precise detection requirements of copper (Cu)-thiocyanate complexes. Compared with traditional sensor technology, MoS2 nanopores can provide higher sensitivity and are particularly suitable for the detection of low-concentration copper (Cu)-thiocyanate complexes.

[0036] 2. Wide range of detection:

[0037] The molybdenum disulfide nanopore chip prepared by the present invention can accurately detect copper (Cu)-thiocyanate complexes in the concentration range of 1 to 12 mmol / L. Compared with traditional methods, it has a wider dynamic detection range and is suitable for real-time monitoring under different pollutant concentrations.

[0038] 3. No marking, no interference detection:

[0039] The present invention realizes label-free detection of copper (Cu)-thiocyanate complex based on nanopore technology, does not need to use any additional labels or reagents, avoids interference factors that may occur in conventional detection, and can provide more reliable detection results.

[0040] 4. Simplified operation process and higher repeatability:

[0041] The present invention detects copper (Cu)-thiocyanate complexes through patch clamp technology and an accurate data acquisition system, achieving rapid and efficient signal analysis. Compared with traditional chemical analysis methods, the operation process is simpler and does not require complicated sample pretreatment, greatly improving experimental efficiency and repeatability, and ensuring stability and consistency in multiple experiments.

[0042] 5. Low cost and strong scalability:

[0043] Since the MoS2 thin film preparation process used in the present invention is simple and low-cost, and the helium ion beam technology can accurately control the preparation process of nanopores, compared with traditional complex detection instruments and chemical analysis methods, the present invention is more cost-effective and has good scalability, and can be widely used in environmental monitoring, wastewater treatment and other fields.

[0044] 6. Multiple application potential for environmental pollutants:

[0045] The sensor based on MoS2 nanopores of the present invention can be widely used in the detection of environmental pollutants, especially in the detection of pollutants in complex environmental samples, showing higher application flexibility and adaptability than traditional methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 A schematic diagram of the device used in the present invention;

[0047] Figure 2 It is a principle diagram of the detection platform of the present invention and a three-dimensional diagram of the structure of the obtained sensor, wherein a is a principle diagram of the detection platform, and b is a three-dimensional diagram of the structure of the obtained sensor;

[0048] Figure 3 This is a schematic diagram of the preparation process of the molybdenum disulfide nanopore chip of the present invention;

[0049] Figure 4 TEM images of the nanopores before and after irradiation with different accelerating voltages described in Examples 1 to 4;

[0050] Figure 5 The data analysis results of the molybdenum disulfide nanopore chip prepared in Example 2 after detecting copper (Cu)-thiocyanate complexes of different concentrations. DETAILED DESCRIPTION

[0051] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0052] It should be understood that the terms described in the present invention are only for describing a particular embodiment and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. The intermediate value in any stated value or stated range, and each smaller range between any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0053] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0054] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present invention description and examples are exemplary only.

[0055] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0056] The structure of the molybdenum disulfide nanopore chip prepared by the present invention is as follows Figure 3 As shown, the prepared molybdenum disulfide nanopore chip includes a silicon substrate, a silicon nitride layer as a suspended membrane substrate, a micron-scale pore structure located at the center of the silicon nitride layer, a molybdenum disulfide layer covering the micron-scale pore structure, and a through nanopore arranged at the center of the molybdenum disulfide layer.

[0057] The detection principle of the present invention is as follows Figure 2As shown in the figure, the detection principle is as follows: the liquid pools on both sides of the MoS2 nanopore chip are made of organic glass, and the MoS2 nanopore chip is clamped in the center of the liquid pool after being sealed with a silicone ring to ensure that the nanopore is the only channel connecting the two ends. When conducting the detection experiment, anhydrous ethanol is first injected into both ends of the liquid pool for wetting treatment, and then replaced with deionized water to remove the residual anhydrous ethanol in the liquid pool, and then the electrolyte solution is injected into the two ports, and the electrodes are inserted into the two sides of the liquid pool respectively to measure the nanopore reference current and IV curve. After completion, the electrolyte solution at the cis end is replaced with the object to be tested, and the object to be tested is tested. The through-hole signal is analyzed according to the sudden drop of the reference current baseline.

[0058] When voltage is applied, molecules suspended in the electrolyte solution pass through the pores and enter the micropores. When a molecule enters the micropore, it occupies a certain space, causing part of the solution to be displaced, resulting in a decrease in ion current. The ion current generated by the electrolyte solution passing through the pores is called the reference current I0. The decrease in current caused by the passage of biological molecules through the pores is called the blocking current △I. The size and concentration of pollutant particles in the electrolyte solution can be analyzed by the blocking current and its duration.

[0059] The silicon nitride chip including the silicon substrate and the silicon nitride layer used in the embodiments and comparative examples of the present invention is prepared by semiconductor processing technology by the following method:

[0060] (1) An n-type medium-resistance silicon wafer with a thickness of 200 μm, double-sided polishing, and a crystal phase plane of (100) is selected as a substrate;

[0061] (2) Using low-pressure chemical vapor deposition, SiH2Cl2 and NH3 are used as reaction gases to deposit a 100 nm thick low-stress silicon nitride film on the upper and lower surfaces of the silicon wafer;

[0062] (3) coating photoresist on one side of silicon nitride, which is defined as the back side of the chip, and patterning a square photoresist window using photolithography;

[0063] (4) Reactive ion etching technology is used, CHF3, SiF6 and He are used as etching gases, and the square window silicon nitride without photoresist protection is etched to expose the substrate and remove the photoresist;

[0064] (5) A wet etching process is used to etch the silicon substrate. A potassium hydroxide solution with a concentration of 30 wt% is used. The solution is heated in a water bath at 80°C for 7 hours. The silicon substrate is etched from the release window. In view of the different etching rates of different crystal planes in silicon, the alkaline solution starts from the exposed silicon window and etches downward along the (111) crystal plane. Finally, the solution reaches the silicon nitride layer on the other side and stops, obtaining a square silicon nitride film with a size of 5 μm × 5 μm.

[0065] (6) The wafer is laser diced into units of 2.4 mm×2.4 mm to obtain a single silicon nitride chip.

[0066] The length, width and height of the silicon nitride chip used are 2.4mm, 2.4mm and 200μm respectively. It includes 0.1μm thick silicon nitride, 200μm thick silicon and 0.1μm thick silicon nitride. At the center of the silicon nitride chip, there is a silicon nitride film with a length, width and height of 5μm, 5μm and 0.2μm.

[0067] Unless otherwise specified, other raw materials used are commercially available products.

[0068] Example 1

[0069] A polymethyl methacrylate (PMMA) solution was spin-coated on one side of a MoS2 film on a silicon dioxide substrate with a single layer of MoS2 film with a thickness of 2 nm. The mass fraction of the PMMA solution was 4%, and the spin coating amount was 150 g / m 2 , and cured at a temperature of 140°C for 10 minutes to form a PMMA-MoS2 film and obtain a PMMA-MoS2-silicon dioxide substrate. Subsequently, the PMMA-MoS2-silicon dioxide substrate was placed in a 2mol / L NaOH solution and soaked for 3 hours to make the PMMA-MoS2 film detach from the silicon dioxide substrate and float on the surface of the solution. Next, the PMMA-MoS2 film was placed in deionized water for cleaning, repeated 3 times, each cleaning time was 10 minutes to remove the solution residue. Then, the PMMA-MoS2 film was placed on top of the silicon nitride chip including the silicon nitride layer of the micron-scale pore structure, and the PMMA-MoS2 film was attached to the chip surface with a tool, and annealed at an annealing temperature of 120°C for 2 hours. After annealing, the chip was soaked in acetone to remove the PMMA layer on the surface of the PMMA-MoS2 film, and repeated 3 times, the soaking time for the first two times was 30 minutes, and the last soaking time was 8 hours. Next, soak it in anhydrous ethanol for 20 minutes, then soak it in deionized water for 15 minutes, and finally dry it in an oven at 70°C to complete the film transfer operation and obtain a molybdenum disulfide chip.

[0070] The molybdenum disulfide chip is processed into nanopores and sized by helium ion beam etching (HIV) and scanning electron microscopy (SEM), and a carbon layer is deposited to obtain the molybdenum disulfide nanopore chip.

[0071] The parameters of helium ion beam etching (HIV) were set as follows: aperture size of 5 μm, ion beam current of 3 pA, circular pattern selection, pattern diameter of 30 nm, dwell time of 1000 μs, pixel size of 1 nm. 2 , ion dose is 20~60nC / μm 2, the interval is 80nm, and the formed nanopore is elliptical with a major-minor axis ratio of 1.1.

[0072] The parameters of the scanning electron microscope (SEM) were set as follows: acceleration voltage of 0.5 kV, processing height of 8 mm, magnification of 100,000 times, scanning range of 1300 nm × 950 nm, current of 2 μA, and irradiation time of 3 s each time.

[0073] The deposition of the carbon layer is as follows: chemical vapor deposition (CVD) technology is used to deposit carbon at the end away from PMMA to form a uniform and dense carbon layer. The specific parameters are as follows: the parameter settings of carbon deposition include a deposition temperature of 700°C, a deposition time of 20min, a gas flow rate of 40sccm, a deposition rate of 0.1nm / s, a gas pressure of 0.8Torr, and acetylene gas is used as the carbon source.

[0074] Example 2

[0075] The difference from Example 1 is that the acceleration voltage in the parameter setting of the scanning electron microscope (SEM) is 1 kV. The rest is the same as Example 1.

[0076] Example 3

[0077] The difference from Example 1 is that the acceleration voltage in the parameter setting of the scanning electron microscope (SEM) is 3 kV. The rest is the same as Example 1.

[0078] Example 4

[0079] The difference from Example 1 is that the acceleration voltage in the parameter setting of the scanning electron microscope (SEM) is 5 kV. The rest is the same as Example 1.

[0080] The TEM images of the nanopores before and after irradiation with different accelerating voltages described in Examples 1 to 4 are as follows: Figure 4 As shown. Figure 4 It can be seen that as the acceleration voltage of the electron beam increases, the change in aperture before and after irradiation becomes smaller and smaller. It also shows that the primary electron acceleration voltage of the electron beam has a great influence on the shrinkage process of MoS2 nanopores.

[0081] Performance Test:

[0082] The test steps are as follows:

[0083] (1) Preparation of copper (Cu)-thiocyanate complex samples: Prepare copper (Cu)-thiocyanate complex standard solutions of different concentrations, with concentrations of 1mmol / L, 4mmol / L, 8mmol / L, and 12mmol / L, respectively. Place the copper (Cu)-thiocyanate complex samples of different concentrations in a mixed solution, which is a mixture of anhydrous ethanol and deionized water in a volume ratio of 1:1 for 10 minutes to ensure that there are no impurities on the sample surface.

[0084] (2) Liquid pool, electrode treatment and sensor preparation: Ag / AgCl was used as the electrode, potassium chloride solution with a concentration of 0.5 mol / L was used as the electrolyte solution, and the bias voltage was set to 200 mV. The liquid pool was ultrasonically cleaned with deionized water and anhydrous ethanol to remove impurities. The Ag / AgCl electrode was pretreated before the experiment. The silver wire was polished with sandpaper to remove the surface oxide layer and residual silver chloride until it showed a metallic luster. The polished silver wire was soaked in a sodium hypochlorite solution until the surface turned black. After soaking, it was washed with deionized water 2 to 3 times to remove the residual sodium hypochlorite solution and other impurities. The potassium chloride solution was degassed to prevent bubbles from causing pore blockage during the experiment. The molybdenum disulfide nanopore chip prepared in Example 2 was clamped in the liquid pool, the liquid pool was divided into two parts, and anhydrous ethanol was injected into the two parts of the liquid pool to increase the hydrophilicity of the liquid pool, and then the residual anhydrous ethanol was removed with deionized water, and finally the electrolyte solution was injected into the liquid pool. The electrodes are placed at both ends of the liquid pool, and the liquid pool and the probe are placed in a shielding box to obtain a sensor. The shielding box is made of 5mm aluminum alloy, and the inside of the shell is fully covered with 0.1mm thick copper foil to protect the amplifier probe, electrodes and liquid pool, and the shell is grounded to minimize external electromagnetic interference, thereby reducing the noise level.

[0085] (3) Current signal acquisition: Use patch clamp technology to acquire current signals. Apply an appropriate bias voltage (200-500mV), set the sampling frequency to 10kHz, and record the current changes in real time. According to experimental needs, analyze the current signal, generate an IV curve, and measure the current amplitude and transit time through the nanopore.

[0086] (4) Data analysis and result processing: Use Clampfit software to draw IV curves and count parameters such as current amplitude and through-hole time. According to the screening criteria (current amplitude is greater than 3 times the through-hole current noise and the signal-to-noise ratio is greater than 3), screen effective signals and analyze the concentration of copper (Cu)-thiocyanate complex. Use Excel and Origin to perform data screening and distribution map drawing, and complete the statistical analysis of the test results. The results are as follows Figure 5 shown.

[0087] Figure 5The data analysis results after the molybdenum disulfide nanopore chip prepared in Example 2 detected copper (Cu)-thiocyanate complexes of different concentrations. Figure 5 It can be seen that different concentrations of copper (Cu)-thiocyanate complexes produce different ion currents. Therefore, the concentration of copper (Cu)-thiocyanate complexes can be determined based on the ion current, thereby realizing the detection of copper (Cu)-thiocyanate complexes in the environment.

[0088] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0089] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a molybdenum disulfide nanopore chip, characterized in that: The steps include: Firstly, a MoS2 layer is deposited on the surface of the substrate, and then a polymethyl methacrylate solution is coated on the surface of the MoS2 layer, and after curing, a substrate with a PMMA-MoS2 film attached is obtained; The substrate with the PMMA-MoS2 film attached is immersed in an alkaline solution to separate the PMMA-MoS2 film from the substrate; The PMMA-MoS2 film is transferred to a silicon nitride chip, and then annealed and PMMA removed to obtain a molybdenum disulfide chip; The molybdenum disulfide chip is subjected to nanopore processing and size control to obtain the molybdenum disulfide nanopore chip.

2. The preparation method according to claim 1, characterized in that: The thickness of the MoS2 layer is 1 to 3 nm; the coating amount is 120 to 400 g / m 2 ; The mass fraction of the polymethyl methacrylate solution is 2 to 4%; and / or, the curing temperature is 120 to 150°C and the curing time is 5 to 10 minutes.

3. The preparation method according to claim 1, characterized in that: The alkali solution includes sodium hydroxide; the concentration of the alkali solution is 2 mol / L; and / or the soaking time is 2 to 3 hours.

4. The preparation method according to claim 1, characterized in that: The silicon nitride chip comprises a silicon substrate and a silicon nitride layer; and / or, the annealing temperature is 100-120° C. and the time is 1-2 hours.

5. The preparation method according to claim 1, characterized in that: The PMMA removal comprises: placing the annealed product in acetone and repeatedly soaking it for 3 times, wherein the time of the first and second soaking is independently 30 to 60 minutes, and the time of the third soaking is 8 hours.

6. The preparation method according to claim 1, characterized in that: Nanopore processing and size control of the MoS2 chip were performed by helium ion beam etching; the parameters of the helium ion beam etching included: aperture size of 5 μm, ion beam current of 3 pA, circular pattern, pattern diameter of 30 nm, dwell time of 1000 μs, pixel size of 1 nm 2 , ion dose is 20~60nC / μm 2 , the interval is 80nm, and the formed nanopore is elliptical with a major-minor axis ratio of 1.05 to 1.

15.

7. The preparation method according to claim 1, characterized in that: Nanopore processing and size control of the molybdenum disulfide chip were performed by scanning electron microscopy; the parameters of the scanning electron microscope included: acceleration voltage of 0.5-5 kV, processing height of 8 mm, magnification of 100,000 times, scanning range of 1300 nm × 950 nm, current of 2 μA, and irradiation time of 3 s each time.

8. A molybdenum disulfide nanopore chip prepared by the preparation method according to any one of claims 1 to 7.

9. Use of the molybdenum disulfide nanopore chip according to claim 8 in the detection of copper-thiocyanate complexes.

10. A method for detecting a copper-thiocyanate complex that improves the sensitivity, selectivity and real-time performance of detection, characterized in that: The method comprises the following steps: detecting the copper-thiocyanate complex by using the molybdenum disulfide nanopore chip according to claim 8.

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