Flexible wearable sensor and preparation method, quercetin determination method

Abstract

The application provides a flexible wearable sensor and a preparation method and a quercetin determination method, relates to the field of quercetin detection, and comprises the following steps: performing laser etching on a to-be-processed mold according to a preset pattern to form a to-be-covered mold; covering the to-be-covered mold with polydimethylsiloxane, performing curing treatment on the to-be-covered mold, obtaining a cured mold, stripping the polydimethylsiloxane film of the cured mold, obtaining a to-be-packaged electrode, coating polydimethylsiloxane to the fourth protruding part; coating silver paste to the third protruding part, heating until curing, and obtaining a cured electrode; immersing the cured electrode into a tetrachloroauric acid solution, depositing gold nanoparticles on the surface of the cured electrode, dropping a mixed solution of black phosphorus solution and naphthol on the first protruding part, and obtaining a flexible wearable sensor after drying. The application has high detection result accuracy and low test cost, and provides accurate judgment basis for the normal growth and development of plants.

Description

Technical Field

[0001] The present invention relates to the field of quercetin detection, and in particular to a flexible wearable sensor and a preparation method thereof, and a quercetin determination method. Background Art

[0002] Quercetin determination based on rigid sensors, such as glassy carbon electrodes and gold electrodes, cannot achieve effective adhesion to the plant surface, thereby reducing the reliability and accuracy of the detection results. In addition, rigid sensors are prone to cause a certain degree of mechanical damage to the plant epidermis, which will affect the normal development of the plant. Summary of the Invention

[0003] The present invention provides a flexible wearable sensor and a preparation method, as well as a quercetin determination method, to solve the technical problem that rigid sensors cannot effectively adhere to plant surfaces. The present invention provides a flexible wearable sensor to achieve effective adhesion to plant surfaces.

[0004] In a first aspect, the present invention provides a method for preparing a flexible wearable sensor, comprising the following steps:

[0005] Laser etching is performed on the mold to be processed according to a preset pattern to form a mold to be covered having a first recess corresponding to the working electrode sensing area, a second recess corresponding to the counter electrode sensing area, a third recess corresponding to the reference electrode sensing area, a fourth recess corresponding to the serpentine conductive area, and a fifth recess corresponding to the electrode connection area;

[0006] Covering the mold to be covered with polydimethylsiloxane, curing the mold to be covered to obtain a cured mold, peeling off the polydimethylsiloxane film of the cured mold to obtain an electrode to be packaged, wherein the electrode to be packaged has a first protrusion corresponding to the working electrode sensing area, a second protrusion corresponding to the counter electrode sensing area, a third protrusion corresponding to the reference electrode sensing area, a fourth protrusion corresponding to the serpentine conductive area, and a fifth protrusion corresponding to the electrode connection area;

[0007] Applying polydimethylsiloxane to the fourth protrusion to insulate and encapsulate the fourth protrusion; applying silver paste to the third protrusion, heating until solidified, and obtaining a solidified electrode;

[0008] The cured electrode was immersed in a tetrachloroauric acid (HAuCl4) solution, and gold nanoparticles (AuNPs) were deposited on the surface of the cured electrode. A mixture of black phosphorus solution and Nafion was dropwise applied to the first protrusion, and a flexible wearable sensor was obtained after drying.

[0009] According to the method for preparing a flexible wearable sensor provided by the present invention, before laser etching the mold to be processed according to a preset pattern, the method further includes: attaching a flexible polyimide tape to a glass plate, ultrasonically cleaning and drying the flexible polyimide tape using ultrapure water or ethanol to obtain the mold to be processed.

[0010] According to the method for preparing a flexible wearable sensor provided by the present invention, the curing treatment of the mold to be covered includes:

[0011] After removing bubbles, heat at 80°C to 120°C for 10 to 12 hours until completely cured.

[0012] According to the method for preparing the flexible wearable sensor provided by the present invention, the insulating package of the fourth protrusion includes: heating at 80° C. to 120° C. for 10 to 12 hours until completely solidified.

[0013] According to the method for preparing the flexible wearable sensor provided by the present invention, after obtaining the cured electrode, the method further comprises:

[0014] The cured electrode was immersed in 0.01 mol / L phosphate buffer with a pH of 7.2 to 7.4 and activated by a constant potential method (1.7 V) for 180 to 360 seconds to remove impurities on the surface of the cured electrode.

[0015] According to the method for preparing a flexible wearable sensor provided by the present invention, depositing gold nanoparticles AuNPs on the surface of the cured electrode comprises:

[0016] Gold nanoparticles AuNPs were electrochemically deposited on the electrode surface using a constant potential method (-1 V) with a deposition time of 1000-1200 s.

[0017] According to the method for preparing a flexible wearable sensor provided by the present invention, the step of applying a mixed solution of black phosphorus solution and Nafion to the first protrusion comprises:

[0018] A 0.1 mg / mL to 0.5 mg / mL black phosphorus solution was mixed with Nafion at a volume ratio of 1:1 to obtain a mixed solution, and 30 μL to 40 μL of the mixed solution was dropwise applied to the first protrusion.

[0019] In a second aspect, a flexible wearable sensor is provided, which is obtained by the above-mentioned method for preparing the flexible wearable sensor;

[0020] The flexible wearable sensor includes at least a first protrusion corresponding to the working electrode sensing area, a second protrusion corresponding to the counter electrode sensing area, a third protrusion corresponding to the reference electrode sensing area, a fourth protrusion corresponding to the serpentine conductive area, and a fifth protrusion corresponding to the electrode connection area;

[0021] The serpentine conductive region comprises a first column of curved conductive regions, a second column of curved conductive regions and a third column of curved conductive regions arranged in sequence, the second column of curved conductive regions is electrically connected to the working electrode sensing region, the first column of curved conductive regions is electrically connected to the counter electrode sensing region, the third column of curved conductive regions is electrically connected to the reference electrode sensing region, and the electrode connecting regions are respectively electrically connected to the first column of curved conductive regions, the second column of curved conductive regions and the third column of curved conductive regions.

[0022] In a third aspect, a determination method of quercetin is provided, which determines the target plant quercetin by using the flexible wearable sensor, and comprises the following steps:

[0023] The surface of the target plant is cleaned, the surface of the target plant is punctured, and the flexible wearable sensor with the working electrode sensing region covered with gelatin electrolyte is attached to the surface of the target plant;

[0024] The target current is obtained according to the differential pulse voltammetry method;

[0025] The target current is input into the quercetin determination model, and a quercetin determination value output by the quercetin determination model is obtained.

[0026] According to the determination method of quercetin provided by the present application, before the flexible wearable sensor with the working electrode sensing region covered with gelatin electrolyte is attached to the surface of the target plant, the following steps are further included:

[0027] Potassium chloride KCl and potassium dihydrogen phosphate KH2PO4 are weighed respectively, placed in a 50mL beaker, deionized water is added, after complete dissolution, the solution pH is adjusted by using hydrochloric acid or potassium hydroxide, a salt solution is obtained, gelatin is added to the salt solution, heated and stirred until completely dissolved, a gelatin mixture is obtained, after cooling, a gelatin electrolyte is obtained;

[0028] The gelatin electrolyte is coated on the working electrode sensing region.

[0029] According to the determination method of quercetin provided by the present application, before the target current is input into the quercetin determination model, the following steps are further included:

[0030] Quercetin-phosphate buffer solutions with concentrations of 0μM, 1μM, 3μM, 5μM, 10μM, 30μM, 50μM and 100μM are prepared, the flexible wearable sensor is used to detect the quercetin-phosphate buffer solutions with different concentrations by the differential pulse voltammetry method, and the current values corresponding to the quercetin-phosphate buffer solutions with different concentrations are obtained;

[0031] A quercetin determination model is constructed according to the current values measured by different concentrations and the quercetin-phosphoric acid buffer solution of each concentration;

[0032] The potential used in the differential pulse voltammetry detection is-0.2V to 0.6V, the potential increment is 0.004V, the amplitude is 0.05V, the pulse width is 0.02s, the pulse period is 0.5s, and the static time is 2s.

[0033] The flexible wearable sensor for detecting quercetin is prepared, the technical defects that the plant physiology cannot be detected in situ and in real time for a long time and the plant sample is damaged are solved, the wearable flexible sensor with high detection result accuracy and low test cost and capable of in situ and real time detection of quercetin in plants is provided, and the preparation method and the determination method are provided, and more accurate judgment basis is provided for normal growth and development of plants. BRIEF DESCRIPTION OF DRAWINGS

[0034] In order to more clearly illustrate the technical solutions in the present application or prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0035] Figure 1 is a structural schematic view of a mold to be covered provided by the present application;

[0036] Figure 2 is a structural schematic view of an electrode to be packaged provided by the present application. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical scheme and advantages of the present application more clear, the technical scheme in the present application will be described clearly and completely in combination with the drawings in the present application. Obviously, the described embodiments are some embodiments of the present application, not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor belong to the protection scope of the present application.

[0038] Flavonoids, also known as bioflavonoids, are polyphenol antioxidants naturally present in plants. Among them, quercetin is one of the most abundant flavonoid compounds, mainly found in grapes, cherries, berries, apples, broccoli, citrus fruits, and onions. This biomolecule has the ability to scavenge reactive oxygen species and has excellent biological activity. Although it is a second metabolite and does not directly participate in plant growth and development, it can provide plants such as flowers and fruits with rich colors. In addition, it plays a vital role in the normal growth and development of plants, and also plays an important role in protecting plants from attacks by microorganisms and pests. The existing methods of using various analytical methods such as capillary electrophoresis, spectrometry, liquid chromatography-tandem mass spectrometry, and high-performance liquid chromatography to detect quercetin content have the disadvantages of high equipment cost, time-consuming synthesis, and complex operation. In particular, these methods are in vitro and require the collection and destructive treatment of plant samples, which cannot achieve real-time monitoring of plant growth.

[0039] Small portable instruments based on electrochemical technology have attracted widespread attention due to their high sensitivity and low cost, and are capable of meeting the needs of in-situ dynamic detection of living plants. Current rigid sensors cannot effectively adhere to the surface of plants, reducing the reliability and accuracy of detection results. In addition, rigid sensors are prone to cause a certain degree of mechanical damage to the plant epidermis, which will affect the normal development of plants. In response to the above technical problems, the present invention provides a flexible wearable sensor and its preparation method, as well as a quercetin determination method. Figure 1 is a schematic structural diagram of the mold to be covered provided by the present invention, Figure 2 This is a schematic diagram of the structure of the electrode to be packaged provided by the present invention. Figure 1 as well as Figure 2 The flexible wearable sensor, its preparation method, and the quercetin determination method of the present invention are described in detail.

[0040] The present invention discloses a method for preparing a flexible wearable sensor, comprising the following steps:

[0041] Laser etching is performed on the mold to be processed according to a preset pattern to form a mold to be covered having a first recessed portion 11 corresponding to the working electrode sensing area, a second recessed portion 12 corresponding to the counter electrode sensing area, a third recessed portion 13 corresponding to the reference electrode sensing area, a fourth recessed portion 14 corresponding to the serpentine conductive area, and a fifth recessed portion 15 corresponding to the electrode connection area;

[0042] The polydimethylsiloxane is used to cover the mold to be covered, the mold to be covered is treated by curing, the mold after curing is obtained, the polydimethylsiloxane film of the mold after curing is stripped, and the electrode to be packaged is obtained, wherein the electrode to be packaged has a first protruding part 21 corresponding to a working electrode sensing area, a second protruding part 22 corresponding to a counter electrode sensing area, a third protruding part 23 corresponding to a reference electrode sensing area, a fourth protruding part 24 corresponding to a serpentine conductive area, and a fifth protruding part 25 corresponding to an electrode connecting area.

[0043] The polydimethylsiloxane is coated on the fourth protruding part, and the fourth protruding part is insulated and packaged; silver paste is coated on the third protruding part, and heating is performed until curing, and the electrode after curing is obtained.

[0044] The electrode after curing is immersed in a tetrachloroauric acid HAuCl4 solution, gold nanoparticles AuNPs are deposited on the surface of the electrode after curing, a mixed solution of black phosphorus and naphthol Nafion is drop-coated on the first protruding part, and a flexible wearable sensor for detecting quercetin is obtained after drying.

[0045] As shown in Figure 1 The present application adopts preset printing data, prints a preset pattern on a mold to be processed based on a laser etching technology, etches a recess part in the mold to be processed, and forms a mold to be covered with a first recess part 11 corresponding to a working electrode sensing area, a second recess part 12 corresponding to a counter electrode sensing area, a third recess part 13 corresponding to a reference electrode sensing area, a fourth recess part 14 corresponding to a serpentine conductive area, and a fifth recess part 15 corresponding to an electrode connecting area.

[0046] After the mold to be covered is obtained, the mold to be covered is covered with polydimethylsiloxane (PDMS), and the mold to be covered is treated by curing, so that the polydimethylsiloxane fills the first recess part 11, the second recess part 12, the third recess part 13, the fourth recess part 14, and the fifth recess part 15, and a polydimethylsiloxane film is formed on the mold to be covered after curing.

[0047] In an optional embodiment, the treatment of the mold to be covered by curing includes: after removing bubbles, heating at 80-120 DEG C for 10-12 hours until complete curing. After the patterned PI tape is covered with polydimethylsiloxane PDMS, the bubbles are removed by vacuum extraction technology, and then the patterned PI tape covered with polydimethylsiloxane is heated at 80-120 DEG C for 10-12 hours until complete curing.

[0048] After obtaining the cured mold, the polydimethylsiloxane film of the cured mold is peeled off, and after removing the mold to be covered, the peeled-off film is the electrode to be encapsulated. The present invention transfers the carbonized graphene to the polydimethylsiloxane. After the patterned PI tape covered with polydimethylsiloxane is completely cured, the film only needs to be gently peeled off to obtain a flexible and stretchable graphene serpentine three-electrode integrated with polydimethylsiloxane.

[0049] Since polydimethylsiloxane is filled in advance, Figure 2 As shown, the electrode to be packaged has a first protrusion 21 corresponding to the working electrode sensing area, a second protrusion 22 corresponding to the counter electrode sensing area, a third protrusion 23 corresponding to the reference electrode sensing area, a fourth protrusion 24 corresponding to the serpentine conductive area, and a fifth protrusion 25 corresponding to the electrode connection area.

[0050] After obtaining the electrode to be packaged, polydimethylsiloxane is first coated on the fourth protrusion, that is, the serpentine conductive area in the present invention, and the fourth protrusion is insulated and packaged. Then, a certain amount of Ag / AgCl silver paste is coated on the exposed third protrusion, and heated until solidified to obtain the solidified electrode, thereby completing the processing of the reference electrode sensing area. The present invention constructs the reference electrode by using silver chloride paste.

[0051] In an optional embodiment, the insulating packaging of the fourth protrusion includes: heating at 80° C. to 120° C. for 10 hours to 12 hours until it is completely cured.

[0052] In another optional embodiment, after obtaining the cured electrode, the method further includes:

[0053] The cured electrode was immersed in 0.01 mol / L phosphate buffer with a pH of 7.2 to 7.4 and activated by a constant potential method (1.7 V) for 180 to 360 seconds to remove impurities on the surface of the cured electrode.

[0054] After completing the treatment of the third and fourth raised portions, a 1 mg / L tetrachloroauric acid (HAuCl4) solution is prepared, the cured electrode is immersed in the tetrachloroauric acid (HAuCl4) solution, gold nanoparticles (AuNPs) are deposited on the surface of the cured electrode, and a mixture of black phosphorus solution and Nafion is dropwise coated on the first raised portion. After drying, a flexible wearable sensor is obtained. The present invention improves the conductive and catalytic properties by depositing gold nanoparticles (AuNPs) on the surface of the cured electrode.

[0055] In an alternative embodiment, the electrode surface is deposited with gold nanoparticles (AuNPs) after solidification, comprising: electrochemically depositing gold nanoparticles (AuNPs) on the electrode surface by using a constant potential method (-1V), and the deposition time is 1000-1200s.

[0056] In an alternative embodiment, the mixed solution of black phosphorus and Nafion is drop-coated on the first protruding part, comprising: mixing 0.1mg / mL-0.5mg / mL black phosphorus solution with Nafion at a volume ratio of 1:1 to obtain a mixed solution, taking 30-40μL of the mixed solution to drop-coat on the first protruding part, i.e., the working electrode sensing area, thereby completing the processing of the working electrode sensing area, and obtaining a flexible wearable biosensor with good sensitivity after natural drying.

[0057] In an alternative embodiment, before laser etching the mold to be processed according to a predetermined pattern, further comprising: pasting a flexible polyimide tape on a glass plate, ultrasonic cleaning and drying the flexible polyimide tape using ultrapure water or ethanol, and obtaining the mold to be processed.

[0058] Optionally, a polyimide (PI) tape is pasted on a 6*6cm 2 glass plate, ultrasonic cleaning is performed using ultrapure water and ethanol, and then a hair dryer is used for drying, a computer-controlled laser system is used for patterning the PI tape, thereby forming a working electrode sensing area, a counter electrode sensing area, a reference electrode sensing area, a serpentine conductive area, and an electrode connection area, and the PI tape is inductively obtained to have an integrated graphene serpentine three-electrode with good conductivity.

[0059] The present application provides a wearable flexible sensor with high detection accuracy and low testing cost, and can detect quercetin in plants in situ in real time, and a preparation method and a determination method thereof, which provides a more accurate basis for judging the normal growth and development of plants.

[0060] According to another aspect of the present application, a flexible wearable sensor is also disclosed, which is obtained by the preparation method of the flexible wearable sensor.

[0061] The flexible wearable sensor at least includes a first protruding part corresponding to a working electrode sensing area, a second protruding part corresponding to a counter electrode sensing area, a third protruding part corresponding to a reference electrode sensing area, a fourth protruding part corresponding to a serpentine conductive area, and a fifth protruding part corresponding to an electrode connection area.

[0062] The serpentine conductive region includes a first column of curved conductive regions, a second column of curved conductive regions, and a third column of curved conductive regions arranged in sequence. The second column of curved conductive regions is electrically connected to the working electrode sensing region, the first column of curved conductive regions is electrically connected to the counter electrode sensing region, and the third column of curved conductive regions is electrically connected to the reference electrode sensing region. The electrode connection region is electrically connected to the first column of curved conductive regions, the second column of curved conductive regions, and the third column of curved conductive regions, respectively. The present invention detects the electrochemical reaction of quercetin through a three-electrode system.

[0063] In an optional embodiment, the flexible wearable sensor mainly includes a flexible sensor module, a signal acquisition module and a wireless transmission module. The flexible sensor module collects the current signal of quercetin information in plants through a flexible serpentine three-electrode surface sensing element and sends the current signal to the signal acquisition module; the signal acquisition module receives the current signal and converts it into a digital signal, and sends the digital signal to a smartphone terminal through a wireless transmission system.

[0064] More specifically, the flexible electrode is prepared by laser printing a drawn pattern on a flexible polyimide tape and then transferring it to polydimethylsiloxane. Ag / AgCl silver paste is coated on it and encapsulated to obtain a flexible serpentine three-electrode system. Gold nanoparticles, black phosphorus and Nafion are modified on the working electrode by electrodeposition, drop coating and other methods, and a solid electrolyte is applied to the modified working electrode. The flexible serpentine three-electrode is then attached to the surface of the plant, and the real-time changes of quercetin in the plant are recorded by differential pulse voltammetry.

[0065] The present invention is a wearable flexible sensor system based on electrochemical detection technology that can achieve rapid, continuous, minimally invasive and real-time collection of quercetin in plants. It is the first case in which a flexible sensor is applied to the detection of plant active small molecules. The detection target is quercetin. In this example, the quercetin content in apples is used as the specific research object; the flexible serpentine three-electrode sensor is modified by means of electrodeposition, drop coating, etc. to achieve high-sensitivity detection of quercetin. This method is used for quercetin detection for the first time; the detection target objects are plant materials, including crops, fruits, vegetables, etc., and the detection parts are plant tissues such as stems, leaves, and fruits.

[0066] The present invention prepares a flexible wearable sensor to address the technical defects of the existing technology, which are the inability to perform long-term in-situ real-time detection of plant physiology and the risk of damaging plant samples. The present invention provides a wearable flexible sensor with high detection accuracy and low testing cost, and can perform in-situ real-time detection of quercetin in plants, as well as a preparation method and a measurement method thereof, thereby providing a more accurate basis for judging the normal growth and development of plants.

[0067] According to another aspect of the present invention, a method for determining quercetin is provided, wherein the flexible wearable sensor is used to determine the quercetin content of a target plant, comprising:

[0068] Cleaning the surface of the target plant, scratching the epidermis of the target plant, and attaching the flexible wearable sensor with the working electrode sensing area covered with gelatin to the epidermis of the target plant;

[0069] obtaining a target current according to differential pulse voltammetry;

[0070] The target current is input into a quercetin measurement model to obtain a quercetin measurement value output by the quercetin measurement model.

[0071] As an optional embodiment of the present invention, apple fruit is selected as the test object, and the quercetin content in the apple is detected in situ and in real time using a wearable flexible sensor. Before detection, the apple surface is first cleaned with deionized water and then dried at room temperature. The apple skin is scratched, and a flexible wearable sensor device equipped with a gelatin semi-solid electrolyte is attached to the apple skin to be tested. Due to the intrinsic adhesion properties of the semi-solid electrolyte and PDMS, the prepared flexible wearable sensor device can self-adhere to the apple surface and be connected to a handheld electrochemical workstation to complete the construction of the flexible wearable sensing system. The real-time changes in the quercetin concentration in the apple are detected by differential pulse voltammetry.

[0072] Experimental results: The present invention selected apples at the mature stage and used the quercetin determination method of the present invention to detect the quercetin content. The results are shown in the following table:

[0073]

[0074] In an optional embodiment, before attaching the flexible wearable sensor with the working electrode sensing area covered with gelatin electrolyte to the epidermis of the target plant, the method further comprises:

[0075] Weigh potassium chloride (KCl) and potassium dihydrogen phosphate (KH2PO4) separately, place them in a 50 mL beaker, add deionized water, and after they are completely dissolved, adjust the pH of the solution with hydrochloric acid or potassium hydroxide to obtain a salt solution, add gelatin to the salt solution, heat and stir until completely dissolved, obtain a gelatin mixture, and cool it to obtain a gelatin electrolyte;

[0076] The gelatin electrolyte is applied to the working electrode sensing area.

[0077] Alternatively, the present invention transfers the gelatin mixture into a syringe and cools and ages it overnight at room temperature until a gel, i.e., a gelatin electrolyte, is formed. Finally, when quercetin detection is required, an appropriate amount of gelatin electrolyte is injected into the working electrode area via syringe, and the electrode is then attached to the apple skin being tested. The present invention utilizes a gelatin electrolyte, allowing the flexible wearable sensor coated with the gelatin electrolyte to remain attached to the plant surface for extended periods of time, thereby enabling real-time monitoring of quercetin.

[0078] In the existing technology, liquid electrolytes are usually attached to the surface of plants, but they cannot be attached for a long time. In order to achieve long-term real-time monitoring of quercetin, the present invention uses gelatin electrolytes to replace the original liquid electrolytes, so that it can be applied to field detection. By combining wearables with smart agricultural application scenarios, unmanned, intelligent, real-time and dynamic detection can be achieved.

[0079] Optionally, before inputting the target current into the quercetin measurement model, the method further comprises:

[0080] Quercetin-phosphate buffer solutions with concentrations of 0 μM, 1 μM, 3 μM, 5 μM, 10 μM, 30 μM, 50 μM, and 100 μM were prepared. Differential pulse voltammetry was performed on the quercetin-phosphate buffer solutions at each concentration using a flexible wearable sensor to obtain the current value corresponding to the quercetin-phosphate buffer solution at each concentration.

[0081] A quercetin determination model was constructed based on the current values ​​measured at different concentrations and each concentration of quercetin-phosphate buffer solution;

[0082] The potential used in the differential pulse voltammetry detection is -0.2V to 0.6V, the potential increment is 0.004V, the amplitude is 0.05V, the pulse width is 0.02s, the pulse period is 0.5s, and the rest time is 2s.

[0083] In an optional embodiment, the present invention can construct a neural network model and obtain a scheme for measuring current values ​​based on the neural network model. Specifically, the current values ​​measured for quercetin-phosphate buffer solutions of different concentrations and each concentration are used as a sample set to construct a neural network model so that the target current is obtained according to differential pulse voltammetry, the target current is input into the quercetin measurement model, and the quercetin measurement value output by the quercetin measurement model is obtained.

[0084] In other embodiments, the current values ​​measured at different concentrations and at each concentration of quercetin-phosphate buffer solution can be linearly fitted to obtain a linear fitting equation, so that when a target current is obtained according to differential pulse voltammetry, the target current is input into the linear fitting equation to obtain a quercetin measurement value. At this time, the present invention will obtain a set of relationship curves between quercetin concentration and peak current after subtracting background current, and prepare a standard curve for quercetin.

[0085] The present invention can realize continuous, minimally invasive and real-time online detection and analysis of quercetin in plants. Compared with traditional rigid electrochemical sensors, flexible electrodes can adapt to the irregular surfaces of plants and can still maintain stable, highly sensitive and specific electrochemical perception under deformation states such as bending and stretching. This method has more accurate detection, traceable response sources, low production costs, simple production processes, high working environment tolerance, and can be applied to field detection. By combining wearables with smart agricultural application scenarios, unmanned, intelligent, real-time and dynamic detection can be achieved.

[0086] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A method for preparing a flexible wearable sensor, characterized in that: The following steps are involved: Laser etching is performed on the mold to be processed according to a preset pattern to form a mold to be covered having a first recess corresponding to the working electrode sensing area, a second recess corresponding to the counter electrode sensing area, a third recess corresponding to the reference electrode sensing area, a fourth recess corresponding to the serpentine conductive area, and a fifth recess corresponding to the electrode connection area; Covering the mold to be covered with polydimethylsiloxane, curing the mold to be covered to obtain a cured mold, peeling off the polydimethylsiloxane film of the cured mold, and obtaining an electrode to be packaged, wherein the electrode to be packaged has a first protrusion corresponding to the working electrode sensing area, a second protrusion corresponding to the counter electrode sensing area, a third protrusion corresponding to the reference electrode sensing area, a fourth protrusion corresponding to the serpentine conductive area, and a fifth protrusion corresponding to the electrode connection area; Applying polydimethylsiloxane to the fourth protrusion to insulate and encapsulate the fourth protrusion; applying silver paste to the third protrusion, heating until solidified, and obtaining a solidified electrode; The cured electrode was immersed in a tetrachloroauric acid (HAuCl4) solution, and gold nanoparticles (AuNPs) were deposited on the surface of the cured electrode. A mixture of black phosphorus solution and Nafion was dropwise applied to the first protrusion, and a flexible wearable sensor was obtained after drying.

2. The method for preparing a flexible wearable sensor according to claim 1, wherein: Before laser etching the mold to be processed according to the preset pattern, In summary, a flexible polyimide tape is attached to a glass plate, and the flexible polyimide tape is ultrasonically cleaned and dried using ultrapure water or ethanol to obtain a mold to be processed.

3. The method for preparing a flexible wearable sensor according to claim 1, wherein: The curing process of the mold to be covered includes: After removing bubbles, heat at 80°C to 120°C for 10 to 12 hours until completely cured.

4. The method for preparing a flexible wearable sensor according to claim 1, wherein: The insulating and encapsulating step of encapsulating the fourth protrusion comprises heating the device at 80° C. to 120° C. for 10 to 12 hours until the device is completely cured.

5. The method for preparing a flexible wearable sensor according to claim 1, wherein: After obtaining the cured electrode, it also includes: The solidified electrode was immersed in a 0.01 mol / L phosphate buffer solution with a pH of 7.2 to 7.4 and activated by a constant potential method for 180 to 360 seconds to remove impurities on the surface of the solidified electrode; The constant potential method is 1.7V.

6. The method for preparing a flexible wearable sensor according to claim 1, wherein: The step of depositing gold nanoparticles AuNPs on the surface of the cured electrode comprises: Gold nanoparticles AuNPs were electrochemically deposited on the electrode surface using a constant potential method with a deposition time of 1000-1200s; The constant potential method is -1V.

7. The method for preparing a flexible wearable sensor according to claim 1, wherein: The step of applying a mixed solution of black phosphorus solution and Nafion to the first protrusion comprises: A 0.1 mg / mL to 0.5 mg / mL black phosphorus solution was mixed with Nafion at a volume ratio of 1:1 to obtain a mixed solution, and 30 μL to 40 μL of the mixed solution was dropwise applied to the first protrusion.

8. A flexible wearable sensor, characterized in that: Obtained by the preparation method of the flexible wearable sensor according to any one of claims 1 to 7; The flexible wearable sensor includes at least a first protrusion corresponding to the working electrode sensing area, a second protrusion corresponding to the counter electrode sensing area, a third protrusion corresponding to the reference electrode sensing area, a fourth protrusion corresponding to the serpentine conductive area, and a fifth protrusion corresponding to the electrode connection area; The serpentine conductive area includes a first column of curved conductive areas, a second column of curved conductive areas and a third column of curved conductive areas arranged in sequence, the second column of curved conductive areas is electrically connected to the working electrode sensing area, the first column of curved conductive areas is electrically connected to the counter electrode sensing area, the third column of curved conductive areas is electrically connected to the reference electrode sensing area, and the electrode connection area is electrically connected to the first column of curved conductive areas, the second column of curved conductive areas and the third column of curved conductive areas respectively.

9. A method for determining quercetin, comprising: using the flexible wearable sensor according to claim 8 to determine quercetin in a target plant; include: Cleaning the surface of the target plant, scratching the epidermis of the target plant, and attaching the flexible wearable sensor with the working electrode sensing area covered with gelatin electrolyte to the epidermis of the target plant; obtaining a target current according to differential pulse voltammetry; The target current is input into a quercetin measurement model to obtain a quercetin measurement value output by the quercetin measurement model.

10. The method for determining quercetin according to claim 9, wherein Before attaching the flexible wearable sensor with the working electrode sensing area covered with gelatin electrolyte to the target plant epidermis, the method further includes: Weigh potassium chloride (KCl) and potassium dihydrogen phosphate (KH2PO4) separately, place them in a 50 mL beaker, add deionized water, and after they are completely dissolved, adjust the pH of the solution with hydrochloric acid or potassium hydroxide to obtain a salt solution, add gelatin to the salt solution, heat and stir until completely dissolved, obtain a gelatin mixture, and cool it to obtain a gelatin electrolyte; The gelatin electrolyte is applied to the working electrode sensing area.

11. The method for determining quercetin according to claim 9, wherein Before inputting the target current into the quercetin measurement model, the method further includes: Quercetin-phosphate buffer solutions with concentrations of 0 μM, 1 μM, 3 μM, 5 μM, 10 μM, 30 μM, 50 μM, and 100 μM were prepared. Differential pulse voltammetry was performed on the quercetin-phosphate buffer solutions at each concentration using a flexible wearable sensor to obtain the current value corresponding to the quercetin-phosphate buffer solution at each concentration. A quercetin determination model was constructed based on the current values ​​measured at different concentrations and each concentration of quercetin-phosphate buffer solution; The potential used in the differential pulse voltammetry detection is -0.2V to 0.6V, the potential increment is 0.004V, the amplitude is 0.05V, the pulse width is 0.02s, the pulse period is 0.5s, and the rest time is 2s.

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