3d cof materials, colorimetric sensing array and preparation method and application thereof
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- HUAZHONG AGRI UNIV
- Filing Date
- 2026-04-10
- Publication Date
- 2026-06-09
Smart Images
Figure CN122167677A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of plant protection technology, specifically to a 3D COF material, a colorimetric sensor array, its preparation method, and its application. Background Technology
[0002] Plant diseases and pests are major factors contributing to global agricultural losses and threatening food security. In the early stages of infection by pathogenic microorganisms (such as Botrytis cinerea and Phytophthora) or pests, plants undergo significant metabolic changes, releasing specific VOCs such as β-phellandrene, certain aldehydes and alcohols, and pest-induced volatile organic compounds (VOCs). These specific VOCs are typically produced before visible damage appears. Therefore, early and rapid monitoring of these characteristic VOCs is of great significance for implementing non-invasive plant health early warning and precise intervention in modern smart agriculture.
[0003] However, existing plant volatile organic compound (VOC) detection technologies face many insurmountable bottlenecks in practical agricultural applications: traditional gas chromatography-mass spectrometry (GC-MS) is expensive, cumbersome to operate, and often requires destructive sampling, making it unable to meet the demand for low-cost, in-situ, real-time, rapid on-site detection; conventional electronic noses lack specific recognition capabilities for complex biological VOCs and are highly susceptible to interference from agricultural background gases, resulting in cross-sensitivity; while existing conventional dye colorimetric sensor arrays have fatal flaws, being highly susceptible to environmental humidity interference and unable to achieve stable responses to ultra-low concentrations of specific VOCs at the ppm level, making them unsuitable for early and accurate warning tasks in complex field or greenhouse environments.
[0004] 3D COFs (Three-dimensional Covalent Organic Frameworks) are a class of crystalline porous polymers with a periodic three-dimensional network structure, formed by strong covalent bonds connecting pure organic monomer molecules as building blocks. Specific organic molecules serve as spatial nodes and connectors within the 3D COF framework. Currently, this material has attracted widespread attention and interest due to its excellent chemical stability resulting from complete covalent bonding, ultra-high porosity and specific surface area, interconnected three-dimensional macropores, and highly tunable pore chemistry microenvironment. In recent years, with the development of materials science, researchers have begun to explore the application of covalent organic frameworks in colorimetric or fluorescence sensing. For example, existing technology (patent publication number CN119613772 A) discloses a method for synthesizing imine-linked COFs using a eutectic solvent and directly using it as a smart colorimetric sensor for the quantitative detection of trace moisture in organic solvents. The core design logic of this type of existing technology is to utilize the highly sensitive fluorescence or colorimetric properties of the COF framework itself to actively capture water molecules. However, such technologies can only be used to measure moisture, and their detection limits are limited to the percentage level, making them completely incapable of detecting the extremely low concentrations and complex compositions of VOCs released by plants in the early stages of stress. Furthermore, agricultural production is accompanied by high humidity and complex water vapor fluctuations; if such moisture-sensitive COF detectors are used directly, background moisture will severely interfere with the detection results.
[0005] How to achieve accurate detection of complex VOCs in high humidity environments is a technical problem that existing technologies need to solve. Summary of the Invention
[0006] To overcome the aforementioned bottlenecks, this invention, based on research findings, utilizes 3D COF materials. Due to their highly developed porosity and well-defined nanopores, 3D COF materials can not only be used for gas adsorption, storage, and separation, but also successfully confine and encapsulate different types of guest molecules within the pores of 3D COF. In practical applications, purely free dyes are highly susceptible to external environmental influences, such as humidity and light, resulting in non-specific color changes that are detrimental to the stable detection of trace gases. By confining the dye within the nanopores of 3D COF, the physical shielding effect of the pores significantly enhances the dye's resistance to interference and chemical stability in complex atmospheric environments.
[0007] Therefore, by using 3D COF to encapsulate different types of stimulus-responsive dyes, we can not only effectively overcome the shortcomings of existing technologies that are easily affected by environmental moisture and have a single detection target, but also make it possible to perform accurate and stable visual detection of plant VOCs with extremely low concentrations and complex compositions.
[0008] The purpose of this invention is to overcome the above-mentioned technical deficiencies and provide a 3D COF material, a colorimetric sensor array, its preparation method and application, thereby solving the technical problem of how to achieve accurate detection of complex VOCs in high humidity environments in the prior art.
[0009] To achieve the above-mentioned technical objectives, the present invention provides a 3D COF material, which is prepared by reacting 4,4′,4″-(1,3,5-triazine-2,4,6-triyl)triphenylamine and tris(4-formylphenyl)amine with a Schiff base.
[0010] Furthermore, the present invention also proposes a method for preparing the 3D COF material according to claim 1, comprising the following steps: dispersing 4,4′,4″-(1,3,5-triazine-2,4,6-triyl)triphenylamine monomer and tri(4-formylphenyl)amine monomer in a solvent, then adding an acidic catalyst and reacting under ultrasonic conditions to obtain the 3D COF material.
[0011] In any embodiment, the mass ratio of the 4,4′,4″-(1,3,5-triazine-2,4,6-triyl)triphenylamine monomer to the tri(4-formylphenyl)amine monomer is (140-145):(130-135).
[0012] In any embodiment, the solvent is dimethyl sulfoxide; and / or, the acidic catalyst is glacial acetic acid.
[0013] In any embodiment, the ultrasound duration is 5-7 minutes.
[0014] Furthermore, the present invention also proposes a colorimetric sensing array, including a substrate and a plurality of colorimetric sensing units loaded on the substrate. The colorimetric sensing units contain a composite color-changing material, which is the above-mentioned 3D COF material with embedded stimulus-responsive dye or the 3D COF material prepared by the above-mentioned preparation method, wherein at least two colorimetric sensing units contain different stimulus-responsive dyes.
[0015] In any embodiment, the stimulus-responsive dye is bromophenol blue, bromocresol green, bromophenol red, bromocresol purple, rhodamine B, methyl orange, or cresol red.
[0016] Furthermore, this invention also proposes a method for fabricating the above-mentioned colorimetric sensing array, comprising the following steps: 3D COF materials containing different dyes were ultrasonically dispersed in a solvent, then spot-coated onto the substrate, and finally dried to obtain the colorimetric sensing array.
[0017] Furthermore, this invention also proposes the application of the above-mentioned colorimetric sensor array or the colorimetric sensor array prepared by the above-mentioned method in non-invasive early warning of plant stress.
[0018] In any implementation, the following steps are included: The colorimetric sensor array is placed in the headspace environment of the target plant to capture VOCs released by the plant; Images of the colorimetric sensor array before and after exposure are obtained, the RGB color values of each sensor unit are extracted and the color difference is calculated to generate the fingerprint spectrum of the volatile substance. The fingerprint spectrum is compared with the PCA classification model to determine the current stress status of the plant and the type of pathogen.
[0019] Compared with the prior art, the beneficial effects of the present invention include: the 3D COF material proposed in this invention is prepared by a Schiff base reaction of 4,4′,4″-(1,3,5-triazine-2,4,6-triyl)triphenylamine and tris(4-formylphenyl)amine; the unique nanoscale channels of the 3D COF material proposed in this invention provide a physical confinement and moisture shielding effect on the stimulus-responsive dye, fundamentally overcoming the fatal flaw of traditional paper-based colorimetric sensors being easily affected by environmental humidity, effectively preventing the aggregation and leakage of dye molecules, ensuring signal stability in complex agricultural high-humidity environments, and realizing accurate detection of complex VOCs in high-humidity environments. Attached Figure Description
[0020] Figure 1 This is a schematic diagram of the fabrication process and material structure of a colorimetric sensing array based on 3D COF material provided in Embodiment 1 of the present invention.
[0021] Figure 2 Scanning electron microscope (SEM) images (a, b) and transmission electron microscope (TEM) images (c, d) of the pure TFPA-TTA framework provided in Example 1 of the present invention and the TFPA-TTA@BPB nanomaterial prepared by adding bromophenol blue dye.
[0022] Figure 3 This is a comparison chart of the anti-interference performance of the colorimetric sensing array based on 3D COF material and the traditional free dye array under different relative humidity environments provided in Embodiment 4 of the present invention; where dye represents free dye, TFPA-TTA represents 3D COF material, and TFPA-TTA@dye is a 3D COF material loaded with dye.
[0023] Figure 4 This is a specific colorimetric fingerprint spectrum of the colorimetric sensor array provided in Embodiment 5 of the present invention after exposure to different plant VOCs.
[0024] Figure 5 This is a schematic diagram of the detection operation device of the colorimetric sensor array provided in Embodiment 6 of the present invention in a non-invasive early warning application of plant stress.
[0025] Figure 6 This is a specific colorimetric fingerprint spectrum of plants infected with Botrytis cinerea, Early blight, and Late blight, as provided in Embodiment 6 of the present invention, after releasing VOCs.
[0026] Figure 7 This is a diagram showing the pattern recognition and principal component analysis classification results of gases released by plants infected with Botrytis cinerea, Early blight, and Late blight using a colorimetric sensor array provided in Embodiment 6 of the present invention. Detailed Implementation
[0027] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60~120 and 80~110 are listed for a specific parameter, it is also expected that ranges of 60~110 and 80~120 are also included. Furthermore, if minimum range values of 1 and 2 are listed, and if maximum range values of 3, 4, and 5 are listed, then the following ranges are all expected: 1~3, 1~4, 1~5, 2~3, 2~4, and 2~5. In this application, unless otherwise stated, the numerical range "a~b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0~5" indicates that all real numbers between "0~5" have been listed in this article; "0~5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.
[0028] Unless otherwise specified, the terms "comprising" and "including" as used in this application can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.
[0029] Unless otherwise specified, the term "or" is inclusive in this application. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, the condition "A or B" is satisfied by any of the following conditions: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).
[0030] This specific embodiment provides a 3D COF material prepared by a Schiff base reaction of 4,4′,4″-(1,3,5-triazine-2,4,6-triyl)triphenylamine and tris(4-formylphenyl)amine.
[0031] This specific embodiment also proposes a method for preparing the above-mentioned 3D COF material, comprising the following steps: dispersing 4,4′,4″-(1,3,5-triazine-2,4,6-triyl)triphenylamine monomer and tris(4-formylphenyl)amine monomer in a solvent, then adding an acidic catalyst and reacting under ultrasonic conditions for 5-7 min to obtain the 3D COF material; the mass ratio of the 4,4′,4″-(1,3,5-triazine-2,4,6-triyl)triphenylamine monomer to the tris(4-formylphenyl)amine monomer is (140-145):(130-135); the solvent is dimethyl sulfoxide; and / or, the acidic catalyst is glacial acetic acid.
[0032] This specific embodiment also proposes a colorimetric sensing array, including a substrate and multiple colorimetric sensing units loaded on the substrate. The colorimetric sensing units contain a composite color-changing material, which is a 3D COF material embedded with a stimulus-responsive dye or a 3D COF material prepared by the above-mentioned preparation method. At least two colorimetric sensing units contain different stimulus-responsive dyes. The stimulus-responsive dyes are bromophenol blue, bromocresol green, bromophenol red, bromocresol violet, rhodamine B, methyl orange, or cresol red.
[0033] This specific embodiment also proposes a method for preparing the above-mentioned colorimetric sensing array, including the following steps: 3D COF materials containing different dyes were ultrasonically dispersed in a solvent, then spot-coated onto the substrate, and finally dried to obtain the colorimetric sensing array.
[0034] This specific embodiment also proposes the application of the above-mentioned colorimetric sensor array or the colorimetric sensor array prepared by the above method in non-invasive early warning of plant stress, including the following steps: The colorimetric sensor array is placed in the headspace environment of the target plant to capture VOCs released by the plant; Images of the colorimetric sensor array before and after exposure are obtained, the RGB color values of each sensor unit are extracted and the color difference is calculated to generate the fingerprint spectrum of the volatile substance. The fingerprint spectrum is compared with the PCA classification model to determine the current stress status of the plant and the type of pathogen.
[0035] Other beneficial effects: The unique nanoscale channels of 1.3D COF provide a physical confinement and moisture shielding effect for the stimulus-responsive dyes, fundamentally overcoming the fatal flaw of traditional paper-based colorimetric sensors that are highly susceptible to environmental humidity interference. This effectively prevents the aggregation and leakage of dye molecules, ensuring signal stability in complex agricultural high-humidity environments.
[0036] 2. The porous framework significantly amplifies the interaction between the host and guest, enabling precise capture and differentiation of complex macromolecular gases with varying polarity, size, and shape. In particular, it achieves ultra-low sensitivity detection of VOCs released by plants under stress such as fungal infection or insect infestation.
[0037] 3. By outputting specific colorimetric fingerprint spectra through the cross-sensitivity of the array and combining them with basic optical spectrum comparison, the target gas can be directly visualized and accurately classified in a very short time after exposure without the need for complex manual judgment or expensive analytical instruments. This provides a fast, low-cost, and universal technical solution for non-invasive plant health monitoring and early disease warning.
[0038] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.
[0039] In this invention, the terms "some embodiments," "this embodiment," and examples are used to describe a subset of all possible embodiments. However, it is understood that "some embodiments" can be the same subset or different subsets of all possible embodiments and can be combined with each other without conflict.
[0040] If the application documents contain similar descriptions such as "first / second", the following explanation shall be added: In the following description, the terms "first / second / third" are used only to distinguish similar objects and do not represent a specific ordering of objects. It is understood that "first / second / third" may be interchanged in a specific order or sequence where permitted, so that the embodiments described herein can be implemented in an order other than that illustrated or described herein.
[0041] In this embodiment, the term "and / or" is merely a description of the relationship between related objects, indicating that there can be three relationships. For example, object A and / or object B can represent three situations: object A exists alone, object A and object B exist simultaneously, and object B exists alone.
[0042] The following describes embodiments of this application. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially. Example 1
[0043] Combination Figure 1 This embodiment proposes a 3D COF material, which is prepared by the following steps: At room temperature, 142 mg of TTA monomer was ultrasonically dispersed in 40 mL of dimethyl sulfoxide (DMSO), followed by the addition of 132 mg of TFPA monomer. Under continuous sonication, 10 mL of glacial acetic acid was slowly added as a catalyst, and sonication was continued for only 5 minutes until a yellow precipitate was formed. The product was filtered, thoroughly washed with anhydrous ethanol and deionized water, and then dried at 60°C for 12 hours to obtain TFPA-TTA 3D COF powder (i.e. 3D COF material).
[0044] This embodiment also proposes a composite color-changing material, which is prepared by the following steps: Dyes with different stimulus response characteristics were selected (including bromophenol blue BPB, bromocresol green BCG, bromophenol red BPR, bromocresol violet BCP, rhodamine B RhB, methyl orange MO, and cresol red CR). Taking BPB as an example, 10 mg of BPB was dissolved in 40 mL of ethanol, and 30 mg of the TFPA-TTA powder prepared above was added. Adsorption was carried out by stirring at room temperature for 12 hours. The precipitate was collected by centrifugation (11000 rpm, 15 min), washed repeatedly with ethanol to remove unconfined free dyes on the surface, and then vacuum dried to obtain TFPA-TTA@BPB nanocomposite material (i.e., a type of composite color-changing material); the preparation process of composite color-changing materials for other dyes is the same as above.
[0045] Combination Figure 1 This embodiment also proposes a colorimetric sensor array, which is prepared by the following steps: Take 60 mg of each of the above-prepared composite color-changing materials and ultrasonically disperse them in 1.2 mL of ethanol to obtain the corresponding composite dispersions; Two μL of each composite dispersion was spot-dropped onto a Whatman chromatography paper substrate (spot diameter approximately 3 mm) to form spatially isolated array units. The residual solvent was evaporated by drying at 65°C for 1 hour to obtain a colorimetric sensor array based on 3D COF material. This colorimetric sensor array includes a substrate and multiple colorimetric sensor units loaded on the substrate. Each colorimetric sensor unit contains a composite color-changing material, which is a 3D COF material embedding a stimulus-responsive dye.
[0046] Figure 2 The images show scanning electron microscope (SEM) images (a, b) and transmission electron microscope (TEM) images (c, d) of pure TFPA-TTA 3D COF powder prepared in this invention and TFPA-TTA@BPB nanomaterials prepared by adding bromophenol blue dye (BPB). As can be seen from the figures, SEM analysis shows that the nanoparticles exhibit a nearly spherical morphology with an average diameter of 48.99 nm. After loading with BPB dye, the spherical morphology of TFPA-TTA is maintained, and BPB molecules are confined and embedded on the outer surface of TFPA-TTA, forming a TFPA-TTA@BPB nanoparticle structure with an average size of 58.46 nm. Example 2
[0047] This embodiment proposes a 3D COF material, which is prepared by the following steps: At room temperature, 140 mg of TTA monomer was ultrasonically dispersed in 40 mL of dimethyl sulfoxide (DMSO), followed by the addition of 135 mg of TFPA monomer. Under continuous sonication, 10 mL of glacial acetic acid was slowly added as a catalyst, and sonication was continued for only 6 minutes until a yellow precipitate was formed. The product was filtered, thoroughly washed with anhydrous ethanol and deionized water, and then dried at 60°C for 12 hours to obtain TFPA-TTA 3D COF powder (i.e. 3D COF material).
[0048] The preparation methods of the composite color-changing material and the colorimetric sensor array in this embodiment are the same as those in Example 1. Example 3
[0049] This embodiment proposes a 3D COF material, which is prepared by the following steps: At room temperature, 145 mg of TTA monomer was ultrasonically dispersed in 40 mL of dimethyl sulfoxide (DMSO), followed by the addition of 130 mg of TFPA monomer. Under continuous sonication, 10 mL of glacial acetic acid was slowly added as a catalyst, and sonication was continued for only 6 minutes until a yellow precipitate was formed. The product was filtered, thoroughly washed with anhydrous ethanol and deionized water, and then dried at 60°C for 12 hours to obtain TFPA-TTA 3D COF powder (i.e. 3D COF material).
[0050] The preparation methods of the composite color-changing material and the colorimetric sensor array in this embodiment are the same as those in Example 1. Example 4
[0051] This embodiment provides a verification of the environmental humidity interference resistance of a sensing array based on 3D COF materials. A control group array (the free dye was directly drop-coated onto chromatography paper or TFPA-TTA) and an experimental group array (the colorimetric sensing array prepared in Example 1) were prepared. Construct a series of controlled humidity environments with relative humidity (RH) ranging from 0% to 90%.
[0052] Three arrays were exposed to varying humidity levels for 2 hours; the Euclidean distance (ED) of the RGB color value difference before and after exposure was calculated. Combined with... Figure 3 As shown in Table 1, the control group exhibited drastic nonspecific color changes with increasing humidity (resulting in severe false positive signals); the experimental group of this invention maintained almost unchanged color value and appearance within a wide humidity range of 0-90%, with extremely low and stable ED values. The pores of the TFPA-TTA framework provided excellent physical shielding and hydrophobic protection for the dye molecules, effectively isolating environmental moisture and ensuring the extremely high stability of the sensing array in high humidity environments.
[0053] Table 1 shows the ED values of the three arrays under different humidity levels in Example 4. Example 5
[0054] This embodiment provides a specific colorimetric reaction and fingerprint pattern construction for various plant-specific VOCs based on a 3D covalent organic framework sensing array: Seven characteristic volatile organic compounds (VOCs) standards closely related to plant diseases and stress were selected, including: β-phellandrene, 4-carene, 2-ethyl-1-hexanol, nonanal, trans-2-hexenal, methyl salicylate, and methyl jasmonic acid. The VOCs were prepared into standard gases of 25 ppm and subjected to headspace reaction with the colorimetric sensor array prepared in Example 1 of the present invention in a sealed environment.
[0055] Compare images before and after array exposure; Figure 4 It is known that due to the slight differences in polarity, acidity / alkalinity, and molecular size of different volatile molecules, after entering the confined channels of the 3D COF material, they produce distinctly weak interactions with the seven dyes with different response mechanisms in the array. This cross-response causes each VOC to generate a different fingerprint spectrum. Example 6
[0056] This embodiment provides an application of a colorimetric sensor array based on a 3D covalent organic framework for early warning of specific volatiles of tomato fungal diseases: See Figure 5 Tomato leaves inoculated with gray mold and healthy control leaves were placed in sealed glass bottles, respectively. The colorimetric sensor array prepared in Example 1 was fixed in the headspace environment inside the bottle and exposed for 1 hour. The infection modes of early blight and late blight of tomatoes are the same as those of gray mold; RGB images of the array before and after exposure were collected. Figure 6 It can be seen that different confined dyes in the array generate specific fingerprint spectra for the characteristic VOCs released by different pathogens. The extracted multidimensional colorimetric fingerprint data (RGB color difference vector) was imported into data analysis software for principal component analysis (PCA). Figure 7 As shown, after dimensionality reduction processing using a pattern recognition algorithm, principal components (such as the first principal component PC1, the second principal component PC2, and the third principal component PC3) explaining the differences in the data were extracted. In the constructed three-dimensional PCA spatial coordinate system, the data points of the healthy control group and the three different pathogens (Botrytis cinerea, Phytophthora virosa, and Phytophthora virosa) infection groups formed distinct and non-overlapping independent clusters.
[0057] The results of this embodiment show that when the real-time fingerprint map acquired by the sensor array is compared with the pre-established PCA classification model, for example, the dimensionality of the fingerprint map actually obtained in the field can be reduced to... Figure 7 On the coordinate axis, observe which pest or disease cluster its spatial coordinate points focus on. If the measured data focuses on the area where early blight of tomato is located, it indicates that the field may be affected by early blight of tomato at this time, and so on. The system can accurately distinguish and warn of the current stress state of the plant when the disease is in its early stage and there are no harmful symptoms.
[0058] The colorimetric sensor array proposed in this invention can perform highly sensitive, non-invasive, and rapid visual detection and early classification and warning of complex volatile organic compounds (VOCs) released by plants when they are subjected to biological stresses such as pathogen infection or insect infestation. It has significant advantages such as low cost, fast response, high accuracy and adaptability to complex agricultural environments.
[0059] The specific embodiments of the present invention described above do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made in accordance with the technical concept of the present invention should be included within the scope of protection of the claims of the present invention.
Claims
1. A 3D COF material, characterized in that, It is prepared by the Schiff base reaction of 4,4′,4″-(1,3,5-triazine-2,4,6-triyl)triphenylamine and tris(4-formylphenyl)amine.
2. A method for preparing the 3D COF material according to claim 1, characterized in that, The process includes the following steps: dispersing 4,4′,4″-(1,3,5-triazine-2,4,6-triyl)triphenylamine monomer and tris(4-formylphenyl)amine monomer in a solvent, then adding an acidic catalyst and reacting under ultrasonic conditions to obtain the 3D COF material.
3. The preparation method according to claim 2, characterized in that, The mass ratio of the 4,4′,4″-(1,3,5-triazine-2,4,6-triyl)triphenylamine monomer to the tri(4-formylphenyl)amine monomer is (140-145):(130-135).
4. The preparation method according to claim 2, characterized in that, The solvent is dimethyl sulfoxide; and / or, the acidic catalyst is glacial acetic acid.
5. The preparation method according to claim 2, characterized in that, The ultrasound session lasted 5-7 minutes.
6. A colorimetric sensor array, characterized in that, The invention includes a substrate and multiple colorimetric sensing units loaded on the substrate. Each colorimetric sensing unit contains a composite color-changing material, which is either the 3D COF material of claim 1 containing a stimulus-responsive dye or a 3D COF material prepared by the preparation method of any one of claims 2-5, wherein at least two colorimetric sensing units contain different stimulus-responsive dyes.
7. The colorimetric sensor array according to claim 6, characterized in that, The stimulus-responsive dye is bromophenol blue, bromocresol green, bromophenol red, bromocresol violet, rhodamine B, methyl orange, or cresol red.
8. A method for fabricating a colorimetric sensor array according to any one of claims 6-7, characterized in that, Includes the following steps: 3D COF materials containing different dyes were ultrasonically dispersed in a solvent, then spot-coated onto the substrate, and finally dried to obtain the colorimetric sensing array.
9. The application of the colorimetric sensor array according to any one of claims 6-7 or the colorimetric sensor array prepared by the preparation method according to claim 8 in non-invasive early warning of plant stress.
10. The application according to claim 9, characterized in that, Includes the following steps: The colorimetric sensor array is placed in the headspace environment of the target plant to capture VOCs released by the plant; Images of the colorimetric sensor array before and after exposure are obtained, the RGB color values of each sensor unit are extracted and the color difference is calculated to generate the fingerprint spectrum of the volatile substance. The fingerprint spectrum is compared with the PCA classification model to determine the current stress status of the plant and the type of pathogen.