A zif-8 gold array impedance sensor and a preparation method and application thereof

Abstract

The application discloses a ZIF-8 gold array impedance sensor and a preparation method and application thereof. The ZIF-8 gold array impedance sensor comprises a gold nanometer film microarray electrochemical impedance sensor and ZIF-8, and the ZIF-8 is modified on the surface of a gold array electrode of the impedance sensor; the gold nanometer film microarray electrochemical impedance sensor comprises a silicon dioxide layer, a chromium layer and a gold array electrode deposited on a silicon wafer. The ZIF-8 modified gold array electrochemical impedance sensor has high structural stability, a sensitive electrochemical impedance signal response, and can selectively adsorb two kinds of mycotoxins in environmental water; the ZIF-8 modified gold electrode has high physical and mechanical strength and stable chemical structure, overcomes the problems that a MOF modified layer of a traditional composite electrode is not easy to modify and is easy to fall off after modification, the sensor has the advantages of a large specific surface area in a working zone, rich adsorption active sites, simple operation, small loading amount, low detection limit, and the like, and can be recycled after a complete test and simple regeneration treatment.

Description

Technical Field

[0001] This invention relates to a ZIF-8 gold array impedance sensor, its preparation method and application, belonging to the field of novel nanomaterials technology. Background Technology

[0002] Metal-organic frameworks (MOFs) are a class of porous coordination polymers composed of metal centers and organic ligands. Due to their unique ultra-high specific surface area, tunable crystal size, and functionalizable internal pores, MOF materials have achieved widespread applications in catalysis, gas storage, and molecular separation, as the high specific surface area and high porosity provide more active sites. Zeolite imidazole framework-8 (ZIF-8) is composed of Zn... 2+ ZIF-8 forms a tetrahedral structure by coordinating with four 2-methylimidazole (2-MI) ligands. Its topological structure originates from the Im-Zn-Im bridge, consistent with the Si-O-Si bridge in zeolites, thus exhibiting thermal stability. It can be stored in air and maintains porosity and ordered crystal orientation in organic solvents, water, and alkaline solutions. The mass synthesis of MOF powders has shown good commercial feasibility, and integrating MOFs into microelectronic regions also holds great potential, such as as sensing coatings and low-k dielectrics. One crucial issue for utilizing the excellent properties of MOFs in microelectronics is developing stable MOF thin film deposition methods. To date, all reported MOF thin film modified array electrodes are based on MOF powder preparation. One method involves synthesizing ZIF-8 powder in the liquid phase, uniformly dispersing ZIF-8 in a solvent, dropping the dispersed solution onto the electrode surface, and then drying it. Another method involves immersing the electrode in a mixed solution of metal salt and organic ligands, where ZIF-8 nucleates on the electrode surface to form a thin film. These liquid-phase film formation methods are incompatible with microelectronic manufacturing processes because contact between pre-fabricated circuits and MOF synthesis solutions can lead to corrosion and chemical contamination. Furthermore, the use of solvents raises safety and cost concerns and conflicts with the "green manufacturing" principles outlined in the microelectronics industry's strategic roadmap.

[0003] Physical vapor deposition (PVD) is a method that, under vacuum conditions, transforms a solid-state material into a gaseous phase through atomic or molecular evaporation, and then deposits the material onto a substrate using plasma generated by glow discharge. Chemical vapor deposition (CVD) is a cornerstone technology in microelectronics manufacturing, where evaporated materials react on or near a substrate to form a uniform thin film of controllable thickness. Using CVD to grow ZIF-8 thin films on array electrode surfaces can solve problems related to solvent contamination and incompatibility with microelectronic manufacturing processes. Chemical vapor conversion of metal-organic frameworks (MOF-CVD) mainly involves two steps: first, depositing an oxide film of a certain thickness as a precursor, and then converting the oxide into MOFs in an organic vapor atmosphere.

[0004] There are six common mycotoxins: aflatoxins (AFs), vomitoxin (DON), fumonisin (FUM), T-2 toxin (zearalenone), and ochratoxin A (OTA). Due to their significant "three-fold" toxicity (carcinogenicity, mutagenicity, and teratogenicity), they seriously threaten human health. Aflatoxins are secondary metabolites produced by Aspergillus flavus and Aspergillus parasiticus. Aflatoxin B1 (AFB1) is the most common aflatoxin, exhibiting significant hepatotoxicity and liver-carcinogenicity in humans, and is classified as a potent carcinogen. Its potency is 10 times that of potassium cyanide and 68 times that of arsenic. The maximum permissible content of AFB1 in infant formula in my country is 0.5 μg / kg. Deoxyfusinol, mainly produced by Fusarium graminearum, Fusarium graminearum, and Fusarium graminearum, is a trichothecene B toxin that can induce vomiting, hence the name vomitoxin (DON). DON exhibits acute toxicity, causing immunotoxicity, cytotoxicity, teratogenicity, and hepatotoxicity. DON is the most common trichothecotoxin, with detection limits typically in the mg / kg range. Therefore, it is necessary to provide a method for detecting mycotoxins based on a microarray sensor. Summary of the Invention

[0005] The purpose of this invention is to provide a ZIF-8 gold array impedance sensor, which is obtained by modifying the surface of a traditional gold array electrode with ZIF-8. ZIF-8 has a high specific surface area and porosity, as well as a large number of active sites, which can be used for efficient and selective adsorption of polycyclic benzene ring small molecule compounds.

[0006] After the ZIF-8 gold array impedance sensor of this invention adsorbs mycotoxins, due to the conductive properties of mycotoxins, as the concentration of adsorbed mycotoxins increases, the number of charge carriers in the gold array ZIF-8 increases, and the sensor impedance decreases, thereby achieving the purpose of quantitative detection of mycotoxins.

[0007] The ZIF-8 gold array impedance sensor of this invention has the advantages of highly efficient selective adsorption of AFB1 and DON, sensitive impedance detection signal, and rapid and stable impedance signal response.

[0008] The ZIF-8 gold array impedance sensor provided by the present invention includes a gold nanofilm microarray and ZIF-8, wherein the ZIF-8 is modified on the surface of the gold array electrode of the gold nanofilm microarray electrochemical impedance sensor.

[0009] The array electrode part consists of a bottom gold array structure and a surface ZIF-8 array structure. The array working area is preferably 2500μm×1980μm, the three-dimensional size of the gold array is preferably 2500μm×10μm×100nm (length×width×height), and the three-dimensional size of the ZIF-8 array is preferably 2500μm×10μm×1.10μm.

[0010] Preferably, the gold nanofilm microarray electrochemical impedance sensor includes a silicon dioxide layer, a chromium layer, and the gold array electrode deposited on a silicon wafer.

[0011] Preferably, the gold array electrode has an array width of 9.9–10.1 μm, an array spacing of 9.9–10.1 μm, a length of 2500–3000 μm, and a gold layer thickness of 100–150 nm.

[0012] The thickness of the ZIF-8 is 750–1150 nm.

[0013] The ZIF-8 gold array impedance sensor of this invention is fabricated using a two-step photolithography and chemical vapor deposition (MOF-CVD) process. In the first photolithography step, a gold array structure is prepared. In the second photolithography step, a ZnO thin film is prepared on the surface of the gold array structure prepared in the first photolithography step using a PVD process. Finally, a ZIF-8 crystal is grown on the ZnO surface using a MOF-CVD process, thus obtaining a combined Au-ZnO-ZIF-8 array structure, which ultimately achieves the modification of the gold array structure.

[0014] Specifically, the method for fabricating the ZIF-8 gold array impedance sensor provided by this invention includes the following steps:

[0015] A zinc oxide layer with a thickness of 110-120 nm, denoted as Au-ZnO, is deposited on the gold surface of the gold nanofilm microarray electrochemical impedance sensor. The Au-ZnO is then transferred in a semi-embedded manner to a reactor containing 2-methylimidazole channels. ZIF-8 is obtained through chemical vapor phase conversion, which is the ZIF-8 gold array impedance sensor.

[0016] The method for preparing the gold nanofilm microarray electrochemical impedance sensor is as follows:

[0017] A silicon dioxide layer, a chromium layer, and a gold layer are sequentially deposited on a silicon substrate;

[0018] A negative photoresist is spin-coated onto the gold layer, and an array of grooves is obtained by ultraviolet exposure and development. The chromium and gold in the array channels are then etched away.

[0019] Specifically, the silicon dioxide layer, the chromium layer, and the gold layer are deposited using an radio frequency (RF) source, with argon (Ar) as the working gas. Preferably, the RF power is 225W and the sputtering time is 45 minutes when sputtering silicon dioxide (SiO2); the RF power is 135W and the sputtering time is 3 minutes when sputtering chromium (Cr); and the RF power is 75W and the sputtering time is 7.5 minutes when sputtering gold (Au). Then, the wafer surface is cleaned with acetone.

[0020] Argon (Ar) ions are used to bombard the wafer surface, etching away all the chromium (Cr) and gold (Au) in the array electrode channels. The fabricated wafer with the gold array electrode structure is then placed in acetone to clean away any remaining photoresist.

[0021] Specifically, positive photoresist is spin-coated onto the surface of the gold array electrode of the gold nanofilm microarray electrochemical impedance sensing, and then zinc oxide is deposited by PVD. After secondary development, excess zinc oxide on the photoresist surface is lifted off, i.e., zinc oxide is modified onto the surface of the gold array electrode. After being diced by a laser scribing machine, the chemical vapor conversion is performed.

[0022] Preferably, a ceramic target is used when sputtering zinc oxide (ZnO), the RF (radio frequency power) is 200W, the oxygen (O2):argon (Ar) ratio is 0.95:1.05, and the sputtering time is 18.5 to 19.5 minutes.

[0023] The chemical vapor conversion employs a temperature control method that uses gradient heating and gradient cooling.

[0024] The gold-zinc oxide (Au-ZnO) microarray sensor chip is embedded in the 2-methylimidazole channels in a semi-embedded manner, and the Au-ZnO microarray is kept stationary in the 2-methylimidazole channels to better form a flat Au-ZIF-8 film on the ZnO surface and 2-methylimidazole through chemical vapor deposition.

[0025] The gradient heating program is as follows: increase the temperature at a rate of 12.5–15 °C / h until it reaches 135–138 °C, and hold for 120–150 min.

[0026] The cooling crystallization procedure is as follows: cool to room temperature at a rate of 5-10℃ / h;

[0027] A reaction at 135℃ for 120 minutes ensures that 2-MI and ZnO react completely to form... <011> ZIF-8 crystals with crystal faces; a cooling program of 20℃ / h can ensure that the ZIF-8 crystals have sufficient cooling and crystallization time, allowing the ZIF-8 crystals to grow to a particle size of about 750~1150nm.

[0028] Compared to traditional impedance sensors, the working electrode of this invention uses ZIF-8 modified gold as the impedance sensing region. This gold exhibits stable crystal layer production, high porosity, numerous adsorption active sites, large specific surface area, and selective adsorption of mycotoxins. Mycotoxins, as small-molecule polycyclic compounds, possess the electrical properties of conductive charge carriers. ZIF-8 can adsorb mycotoxins in environmental water, causing a change in electrochemical impedance signal where the impedance decreases with increasing adsorbate concentration, thus enabling the quantitative detection of mycotoxins in environmental water.

[0029] The Au-ZIF-8 microarray sensor of this invention can adsorb mycotoxins, and therefore can be used for the electrochemical detection of mycotoxins in samples (environmental water, animal feed, animal-derived foods (chicken, eggs, milk, honey)).

[0030] The ZIF-8 gold array impedance sensor of this invention has a detection range of 1.0 fg / mL to 1.0 ng / mL for aflatoxin B1 (AFB1) vomitoxin (DON) in environmental water, and the limit of detection of this ZIF-8 impedance sensor is 1.0 fg / mL. This impedance sensor features high mycotoxin adsorption efficiency, sensitive impedance signal response, and a stable and robust ZIF-8 adsorption layer structure.

[0031] The impedance sensor of this invention, after adsorbing mycotoxins on its ZIF-8 surface, is eluted with acetone and methanol, regenerated with pure water, and dried with nitrogen, allowing for recyclability. This sensor can efficiently and accurately adsorb and detect various mycotoxins in environmental water, and shows promising potential for future expansion into the adsorption and detection of other toxic small molecule compounds, heavy metals, and pathogenic microorganisms.

[0032] The Au-ZIF-8 microarray sensor of this invention uses deionized water as the medium solution after adsorbing mycotoxins, which can minimize impedance interference caused by the adsorption of conductive ions from other electrolyte solutions on the ZIF-8 surface of the sensor.

[0033] The ZIF-8 modified gold array electrochemical impedance sensor of this invention is a device with high structural stability, sensitive electrochemical impedance signal response, and selective adsorption of two mycotoxins (AFB1 and DON) in environmental water. The ZIF-8 modified gold electrode has high physical and mechanical strength and stable chemical structure, overcoming the problems of difficult modification and easy detachment of MOF modification layer in traditional composite electrodes. The sensor has the advantages of large specific surface area of ​​working area, rich adsorption active sites, simple operation, small sample loading, low detection limit, and can be recycled after simple regeneration after a complete test. Attached Figure Description

[0034] Figure 1 This is a flowchart illustrating the fabrication process of the Au-ZIF-8 microarray electrode of this invention.

[0035] Figure 2 The microstructure characterization images of the Au-ZIF-8 microarray electrode prepared in Example 1 of this invention are as follows: A1 is a SEM image of Au-ZnO; A2 is a magnified SEM image of Au-ZnO; A3 is an AFM image of Au-ZnO; A4 is an AFM image of the channel of Au-ZnO; A5 is a magnified AFM image of Au-ZnO; B1 is an EDS elemental energy distribution map of Au-ZnO; B2 is an AFM surface roughness map of Au-ZnO; C1 is a SEM image of Au-ZIF-8; C2 is a magnified SEM image of Au-ZIF-8; C3 is a SEM image of ZIF-8 crystal particles in Au-ZIF-8; C4 is an AFM image of the channel of Au-ZIF-8; D1 is an EDS elemental energy distribution map of Au-ZIF-8; D2 is a magnified AFM image of the channel of Au-ZIF-8.

[0036] Figure 3 The Nyquist plot and detection linear range of AFB1 in the water of the Au-ZIF-8 microarray sensor in Embodiment 2 of the present invention are shown. Figure 3 The measured Nyquist spectrum of AFB1 was 1.0 fg / mL to 1.0 ng / mL. Figure 3 b represents the standard curve for the detection range of AFB1.

[0037] Figure 4 The Nyquist plot and detection linear range of DON in the water test environment of the Au-ZIF-8 microarray sensor in Embodiment 3 of the present invention are shown. Figure 4 The measured Nyquist spectrum of AFB1 was 1.0 fg / mL to 1.0 ng / mL. Figure 4 b represents the standard curve for the DON detection range.

[0038] Figure 5Nyquist plot and detection linear range of CPA in water test environment for Au-ZIF-8 microarray sensor ( Figure 5 The measured Nyquist spectrum of AFB1 was 1.0 fg / mL to 1.0 ng / mL. Figure 5 b represents the standard curve for the CAP detection range.

[0039] Figure 6 A flowchart illustrating the fabrication of Au-ZIF-8 microarray sensor chips using a 2-methylimidazole prefabrication tunnel CVD process. Figure 6 Au-ZIF-8 was prepared using a 2-methylimidazole pre-cast tunnel CVD process. Figure 6 b is the preparation of Au-ZIF-8 using a traditional planar 2-methylimidazole CVD process. Detailed Implementation

[0040] Unless otherwise specified, the experimental methods used in the following examples are conventional methods.

[0041] Unless otherwise specified, all materials and reagents used in the following examples are commercially available.

[0042] Example 1: Fabrication of ZIF-8 gold array microelectrodes

[0043] Preparation flow chart as follows Figure 1 As shown.

[0044] A four-inch silicon dioxide (N-type silicon dioxide) wafer was immersed and washed in 50 mL of acetone for 15 min. A 300 nm thick SiO2 layer, a 10 nm thick Cr metal layer, and a 100 nm thick Au gold layer were then physically vapor-deposited onto the clean Si wafer surface. A 2 μm thick negative photoresist was spin-coated onto the wafer surface and subjected to UV exposure to form the working electrode pattern. After development, the electrode working area with a gold array recessed shape was obtained.

[0045] Next, a 2μm thick positive photoresist is spin-coated onto the gold array electrode sheet, followed by physical vapor deposition (PVD) of 100nm zinc oxide (ZnO). After a second exposure and development, the ZnO pattern is transferred to the working area of ​​the gold array electrode, i.e., the array area.

[0046] Finally, the silicon wafer is diced using a laser dicing machine, and individual gold-zinc oxide (Au-ZnO) array electrodes are placed in pre-formed channels made of 2-methylimidazole powder in a semi-embedded manner (e.g., Figure 6As shown), and put it into a reaction vessel, the zinc oxide film is converted into ZIF-8 by chemical vapor conversion (MOF-CVD) with a gradient heating program of 15℃ / h until it reaches 135℃, held for 150min, and then cooled and crystallized at 10℃ / h until it reaches room temperature.

[0047] Depend on Figure 6 As can be seen from a, the 2-methylimidazole tunnel CVD process used in this invention can grow well-crystallized ZIF-8 crystals on the Au-ZnO surface, which is the Au-ZIF-8 microarray sensor. In contrast, the traditional planar 2-methylimidazole CVD process (see...) Figure 6 b) Well-formed ZIF-8 crystals cannot be prepared on Au-ZnO surfaces.

[0048] The ZIF-8 gold array microelectrode structure parameters prepared in this embodiment are: array width 10 μm, array spacing 10 μm, length 2500 μm, Au height 100 nm, and ZIF-8 height 750–1150 nm.

[0049] The surface microstructure and elemental distribution of the ZIF-8 gold array prepared in this embodiment are as follows: Figure 2 Analysis of the various figures reveals that, Figure 2 SEM analysis of the gold-zinc oxide (Au-ZnO) microarray in A1 showed that the array width was 10 μm. Figure 2 A2 shows that ZnO is uniformly distributed on the Au surface; Figure 2 A3-A5 are the AFM diagrams of the Au-ZnO array; Figure 2 B1 is the element distribution diagram of the Au-ZnO array; Figure 2 B2 represents the AFM thickness (37 nm) of the Au-ZnO array; Figure 2 C1 is a SEM image of the Au-ZIF-8 array; Figure 2 C2 represents the particle distribution of ZIF-8 crystals in the Au-ZIF-8 array; Figure 2 C3 is a SEM image of a single ZIF-8 crystal in the Au-ZIF-8 array; Figure 2 C3 is the SEM image of the Au-ZIF-8 array; Figure 2 D1 is the element distribution diagram of the Au-ZIF-8 array; Figure 2 D2 is the AFM characterization diagram of the roughness of ZIF-8 crystal particles on the surface of the Au-ZIF-8 array.

[0050] Example 2: Adsorption and detection of AFB1 in ambient water by Au-ZIF-8 microarray electrode

[0051] The ZIF-8 gold electrode prepared in Example 1 was cleaned with 5 mL of methanol. 10 μL of AFB1 environmental water sample with a concentration of 1.0 fg / mL to 1.0 ng / mL was accurately pipetted and added to the working area surface of the ZIF-8 gold electrode array. The sample was then allowed to stand at 25°C for 20 min. The electrode surface was then washed with deionized water. Immediately after washing, 10 μL of deionized water was added to the cleaned sensor surface for impedance testing. The impedance scan frequency was 10–100 kHz, and the DC bias voltage was 0 V. The measured impedance Nyquist spectrum and detection linear range of AFB1 in the environmental water are shown below. Figure 3 As shown.

[0052] Depend on Figure 3 a is the frequency impedance diagram of the Au-ZIF-8 microarray sensor for different concentrations of aflatoxin B1 (AFB1) in water; Figure 3 b refers to the Au-ZIF-8 microarray sensor, which has a detection range of 1.0 fg / mL to 1.0 ng / mL for aflatoxin B1 in water.

[0053] Example 3: Adsorption and Detection of DON in Ambient Water Using Au-ZIF-8 Microarray Electrode

[0054] The ZIF-8 gold electrode prepared in Example 1 was cleaned with 5 mL of methanol. 10 μL of DON-containing ambient water sample (concentration 1.0 fg / mL–1.0 ng / mL) was precisely pipetted and added to the working area of ​​the ZIF-8 gold electrode array. The sample was then incubated at 25°C for 20 min. The electrode surface was then washed with deionized water. Immediately after washing, 10 μL of deionized water was added to the cleaned sensor surface for impedance testing. The impedance scan frequency was 10–100 kHz, and the DC bias was 0 V. The measured impedance Nyquist spectrum and detection linear range of DON in ambient water are shown below. Figure 4 As shown.

[0055] Figure 4 a is the frequency impedance diagram of the Au-ZIF-8 microarray sensor for different concentrations of vomiting toxin (DON) in water; Figure 4 b represents the Au-ZIF-8 microarray sensor, which has a detection range of 1.0 fg / mL to 1.0 ng / mL for DON in water.

[0056] Example 4: Adsorption and Detection of Chloramphenicol (CAP) in Environmental Water Using Au-ZIF-8 Microarray Electrode

[0057] The ZIF-8 gold electrode prepared in Example 1 was cleaned with 5 mL of methanol. 10 μL of a CAP environmental water sample solution with a concentration of 1.0 fg / mL to 1.0 ng / mL was accurately pipetted and added dropwise to the working area surface of the Au-ZIF-8 microarray electrode array. The solution was incubated at 25°C for 20 min. The electrode surface was then washed with deionized water. Immediately after washing, 10 μL of deionized water was added to the cleaned sensor surface for impedance testing. The impedance scan frequency was 10–100 kHz, and the DC bias voltage was 0 V. The measured impedance Nyquist spectrum and detection linear range of CAP in environmental water are shown in the figure. Figure 5 .

[0058] Figure 5 a is the frequency impedance diagram of the Au-ZIF-8 microarray sensor for different concentrations of chloramphenicol (CAP) in water; Figure 5 b is the Au-ZIF-8 microarray sensor, which has a detection range of 1.0 fg / mL to 1.0 ng / mL for CAP in water.

[0059] The detection results of the Au-ZIF-8 microarray sensor (10μm spacing) and the GCE-ZIF-8 sensor of the present invention are shown in Table 1. It can be seen that the Au-ZIF-8 sensor with 10μm spacing of the present invention has higher sensitivity than the traditional ZIF-8 sensor using glassy carbon electrodes when detecting AFB1, DON and CAP.

[0060] Table 1. Comparison of Limits of Quantitation (LOQ) between Au-ZIF-8 and GCE-ZIF-8 with a 10 μm spacing

[0061]

[0062] Table 2 shows a comparison of the detection performance of the Au-ZIF-8 microarray sensor of this invention with other electrochemical chips for detecting mycotoxins. The Au-ZIF-8 electrode of this invention has a detection limit of quantitation as low as 1.0 fg / mL for aflatoxin B1 (AFB1) and vomitoxin (DON). -15 The results show that this method is superior to other gold electrodes modified with gold polymers, indium tin oxide, and multi-walled carbon nanotubes for the detection of mycotoxins.

[0063] Table 2 Comparison of the detection performance of Au-ZIF-8 and other electrochemical chips for mycotoxins

[0064]

[0065] Reference [1] is: Zenghui Liu, Jinyan Xue, Luyao Chen, Lele Ma, Huaixia Yang, Yaping Zhang, Mingsan Miao, A signal-off aptamer sensor based on competition with complementary DNA and click polymerization for electrochemical detection of AFB1, Microchemical Journal, 2022, 181, 107775. https: / / doi.org / 10.1016 / j.microc.2022.107775.

[0066] Reference [2] is: Lin Lu, Sundaram Gunasekaran, Dual-channel ITO-microfluidic electrochemical immunosensor for simultaneous detection of two mycotoxins, Talanta, 2019, 194:709-716. https: / / doi.org / 10.1016 / j.talanta.2018.10.091.

[0067] Reference [3] is: Lili Yu, Yang Zhang, Chenyi Hu, Hui Wu, Yayun Yang, Chusen Huang, Nengqin Jia, Highly sensitive electrochemical impedance spectroscopy immunosensor for the detection of AFB1 in olive oil, Food Chemistry, 2015, 176, 22-26. https: / / doi.org / 10.1016 / j.foodchem.2014.12.030.

Claims

1. A ZIF-8 gold array impedance sensor, comprising a gold nanofilm microarray electrochemical impedance sensor and ZIF-8, wherein the ZIF-8 is modified on the surface of the gold array electrode of the gold nanofilm microarray electrochemical impedance sensor.

2. The ZIF-8 gold array impedance sensor according to claim 1, characterized in that: The gold nanofilm microarray electrochemical impedance sensor includes a silicon dioxide layer, a chromium layer, and the gold array electrode deposited on a silicon wafer.

3. The ZIF-8 gold array impedance sensor according to claim 1 or 2, characterized in that: The gold array electrode has an array width of 9.9~10.1 μm, an array spacing of 9.9~10.1 μm, a length of 2500~3000 μm, and a gold layer thickness of 100~150 nm; the ZIF-8 has a thickness of 750~1100 nm.

4. A method for fabricating the ZIF-8 gold array impedance sensor according to any one of claims 1-3, comprising the following steps: A zinc oxide layer with a thickness of 110-120 nm, denoted as Au-ZnO, is deposited on the gold surface of the gold nanofilm microarray electrochemical impedance sensor. The Au-ZnO is then transferred in a semi-embedded manner to a reactor containing 2-methylimidazole channels. ZIF-8 is obtained through chemical vapor phase conversion, which is the ZIF-8 gold array impedance sensor.

5. The preparation method according to claim 4, characterized in that: The method for preparing the gold nanofilm microarray electrochemical impedance sensor is as follows: A silicon dioxide layer, a chromium layer, and a gold layer are sequentially deposited on a silicon substrate; a negative photoresist is spin-coated onto the gold layer, and an array of grooves is obtained by ultraviolet exposure and development, and the chromium and gold in the array channels are etched away.

6. The preparation method according to claim 5, characterized in that: Positive photoresist is spin-coated onto the surface of the gold electrode in the gold nanofilm microarray electrochemical impedance sensor, and then zinc oxide is deposited. After secondary development, zinc oxide is modified onto the surface of the gold array electrode. After dicing with a laser scribing machine, the chemical vapor conversion is performed.

7. The preparation method according to any one of claims 4-6, characterized in that: The 2-methylimidazole channels are matched with the microarray size of Au-ZnO so that the Au-ZnO is embedded in the 2-methylimidazole channels in a semi-embedded manner. The chemical vapor conversion employs a temperature control method that uses gradient heating and gradient cooling. The gradient heating program is as follows: increase the temperature at a rate of 12.5~15℃ / h until it reaches 135~138℃, and hold for 120~150 min; the cooling crystallization program is as follows: decrease the temperature to room temperature at a rate of 5~10℃ / h.

8. The application of the ZIF-8 gold array impedance sensor according to any one of claims 1-3 in the electrochemical detection of mycotoxins in samples.

9. The application according to claim 8, characterized in that: The mycotoxin is aflatoxin B1, vomitoxin, or chloramphenicol; The samples were environmental water, animal feed, or animal-derived food. The concentration of mycotoxins in the sample was 1.0 fg / mL to 1.0 ng / mL.

10. The application according to claim 8 or 9, characterized in that: Deionized water was used as the medium solution.

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