A flexible multi-gate single-channel OECT molecularly imprinted sensor and its fabrication method

Abstract

This invention provides a flexible multi-gate single-channel OECT molecularly imprinted sensor and its fabrication method, belonging to the field of flexible chemical sensor technology. This sensor employs a unique multi-gate single-channel integrated structure with gates symmetrically arranged at equal intervals around the source and drain electrodes and synergistically controlled within the same channel. Combined with MIP and OECT technologies, it possesses both high-sensitivity amplification capability and highly specific recognition of three non-electroactive BCAAs (leucine, isoleucine, and valine), enabling the detection of multiple substances with a single device.

Description

Technical Field

[0001] This invention belongs to the field of flexible chemical sensor technology, specifically relating to a flexible multi-gate single-channel organic electrochemical transistor (OECT) molecularly imprinted sensor and its fabrication method. Background Technology

[0002] Branched-chain amino acids (BCAAs), including leucine (Leu), isoleucine (Lle), and valine (Val), are important biomarkers for maintaining metabolic homeostasis and reflecting various disease states. Changes in their concentration are closely related to metabolic syndrome, diabetes, liver disease, and exercise physiology. Therefore, rapid, sensitive, and accurate detection of BCAAs is of great significance for disease screening and health monitoring. However, BCAAs are typical non-electrolyzable small molecules, making direct redox reactions at electrode interfaces difficult, which significantly limits the sensitivity and selectivity of traditional electrochemical detection methods.

[0003] Currently, commonly used BCAA (Brain-Based Acute Recognition) analysis methods mainly rely on large instruments such as liquid chromatography and mass spectrometry. Although these methods offer high detection accuracy, the equipment is expensive, the analytical procedures are complex, and the detection cycles are long, making it difficult to meet the needs of portable, real-time monitoring, and wearable applications. To improve the recognition selectivity of small molecules, molecular imprinting (MIP) technology has attracted attention in recent years. By constructing specific recognition sites in polymers, highly selective binding to target small molecules can be achieved. However, the signals generated at the MIP interface are generally weak, requiring high-gain signal amplification structures to achieve sensitive detection.

[0004] Organic electrochemical transistors (OECTs), due to their efficient ion-electron coupling and transconductance amplification capabilities, can amplify weak interfacial changes into significant channel currents, making them an ideal platform for enhancing MIP signal output. However, current OECT biosensors are still mostly limited to traditional single-gate structures, such as glucose monitoring achieved by Abdulelah Saleh et al. and growth factor detection conducted by Xudong Ji et al. Such designs can only achieve responses to a single specific analyte, failing to meet the core demands of modern clinical diagnostics for parallelization and system integration of multiple biomarkers. In contrast, multi-gate integrated architectures exhibit significant structural and functional advantages. By arraying multiple independent and functional gates within the same sensing unit, this structure enables real-time monitoring of multiple target biomarkers in a single sampling process, greatly improving diagnostic efficiency. Simultaneously, the multi-gate design effectively improves the space utilization of the chip surface, allowing for high integration of the sensing unit within a limited area, perfectly meeting the requirements of miniaturization and functional diversification in flexible electronic devices. However, traditional multi-gate structures also have certain limitations. For example, gates are usually arranged in a vertical or linear pattern. The geometric distance between different gates and channels is inconsistent, which can easily lead to differences in ion transport paths and uneven electric field distribution, thus causing problems such as gate control efficiency deviation and inconsistent signal strength. When the flexible substrate is bent, the above-mentioned inhomogeneity is further amplified, thereby affecting the detection stability and repeatability.

[0005] Therefore, there is an urgent need to develop a sensor structure that can achieve multi-gate collaborative detection on a flexible substrate and simultaneously possess high sensitivity amplification capability and specific molecular recognition characteristics, so as to achieve rapid and accurate detection of a variety of BCAAs. Summary of the Invention

[0006] To address the problems existing in the background technology, the present invention aims to provide a flexible multi-gate single-channel OECT molecular imprinted sensor and its fabrication method. This sensor employs a unique multi-gate single-channel integrated structure with gates symmetrically arranged at equal intervals around the source and drain electrodes and synergistically controlled within the same channel. Combining MIP and OECT technologies, it possesses both high-sensitivity amplification capability and highly specific recognition of three non-electroactive BCAAs (leucine, isoleucine, and valine), enabling the detection of multiple substances with a single device.

[0007] To achieve the above objectives, the technical solution of the present invention is as follows:

[0008] A flexible multi-gate single-channel OECT molecular imprint sensor includes a flexible substrate, and a source, a drain, and three gates disposed on the surface of the substrate.

[0009] The source and drain have similar structures, each consisting of an arc, a long rectangular strip, and a rectangular block. One end of the long rectangular strip is connected to the arc, and the other end is connected to the rectangular block. The arcs of the source and drain are distributed vertically and do not touch each other. The centers of the arcs are located on the same side of the arcs. The diameters and lengths of the two arcs are different, and the fan-shaped area formed between them serves as the channel region. The channel is formed by PEDOT:PSS covering this channel region.

[0010] Three gates are evenly distributed around the source and drain. Each gate includes a fan-shaped sensing region, a metal connection line connected to the fan-shaped sensing region, and a rectangular block. The distance from the center of the three fan-shaped sensing regions to the center of the channel fan is equal.

[0011] The fan-shaped sensing region of the gate is obtained by modifying a laser-induced graphene electrode with Prussian blue (PB) as a redox probe, and then modifying it with a molecularly imprinted polymer film.

[0012] Furthermore, the transistor channel is fan-shaped, with a radial length to arc length ratio of (15-20):1.

[0013] Furthermore, to improve the conductivity, electrochemical activity, and specific surface area of ​​the gate sensing electrode, the gate sector sensing region is modified with MXene material before being modified with the redox probe.

[0014] A method for fabricating a flexible multi-gate single-channel OECT molecularly imprinted sensor includes the following steps:

[0015] S1. Preparation of flexible polyimide (PI) substrates;

[0016] S2. Patterned source and drain electrodes are fabricated on the surface of a flexible substrate using a photolithography-magnetron sputtering process;

[0017] S3. Preparation of fan-shaped PEDOT:PSS channels:

[0018] A conductive polymer solution, PEDOT:PSS, is spin-coated onto the substrate surface and annealed. A photoresist pattern is then formed in the channel region between the source and drain electrodes. The PEDOT:PSS film not protected by the photoresist is selectively removed by plasma etching. Finally, the residual photoresist is removed by solvent washing, leaving PEDOT:PSS only in the designated connection region between the source and drain electrodes, thereby forming a conductive channel.

[0019] S4. Three fan-shaped laser-induced graphene (LIG) gate electrodes were fabricated on a substrate using CO2 laser processing technology;

[0020] S5. Modified PB was prepared on a sector-shaped LIG electrode by an electrochemical method to serve as a redox probe;

[0021] S6. A molecularly imprinted polymer (MIP) capable of specifically recognizing BCAAs is prepared on a sector-shaped LIG-PB electrode to obtain the desired molecularly imprinted sensor.

[0022] Furthermore, in S3, the PEDOT:PSS solution comprises PEDOT:PSS, ethylene glycol, 3-glycidyl etheroxypropyltrimethoxysilane, and dodecylbenzenesulfonic acid.

[0023] Furthermore, before modifying the redox probe on the gate surface in step S5, the LIG electrode is first modified with MXene material, which is prepared by drop coating.

[0024] Furthermore, the optimal amount of MXene material for modification is 40-50 microliters.

[0025] Furthermore, the electrochemical method in step S5 is preferably cyclic voltammetry, the specific process of which is as follows: immersing the LIG electrode in the PB deposition solution, performing cyclic scanning at a scan rate of 30-50 mV / s within a potential range of -0.2 V to 0.6 V, and performing 120-140 cyclic deposition cycles to form a uniform PB redox probe layer.

[0026] Further, in step S6, the MIP electropolymerization solution is a solution composed of the template to be tested, 3-aminophenylboronic acid (APBA), pyrrole, and phosphate buffer solution (PBS). 3-aminophenylboronic acid (APBA), as a functional monomer, has its phenylboronic acid groups that bind to the template molecules through reversible interactions, constructing highly specific imprinted holes. Pyrrole, as the main polymerization monomer, forms a conductive and structurally stable polypyrrole (PPy) framework during electrochemical polymerization, providing mechanical support and electronic conduction pathways for the molecularly imprinted layer.

[0027] The templates to be tested are valine, leucine, and isoleucine.

[0028] The mechanism of this invention is as follows:

[0029] The sensing electrode used in this invention consists of three LIG gates formed by CO2 laser processing. Each gate has a three-dimensional porous structure, high specific surface area, and excellent conductivity, providing abundant active sites for electrochemical modification. Based on this, by modifying the LIG surface with an MXene layer, the conductivity and surface hydrophilicity of the electrode interface are further improved, enhancing electron transport efficiency and facilitating uniform deposition of PB. Subsequently, a PB redox probe is prepared on the LIG-MXene electrode surface via electrochemical deposition, which reversibly deposits Fe...2+ / Fe 3+ The electrochemical reaction generates a stable signal at low potentials, providing a measurable current response for non-electroactive molecules. Finally, a MIP is prepared on the LIG-MXene-PB modified electrode surface via electrochemical polymerization, forming a recognition cavity highly complementary to the BCAAs template molecules, enabling specific recognition of the target molecule.

[0030] This invention designs multiple gates within a single sensor, with the geometric spacing between the three gates and the channel being consistent. Compared to traditional vertical linear arrangements, this equidistant distribution effectively reduces inconsistencies in ion diffusion paths and gate control efficiency deviations caused by spatial differences, ensuring that each gate has the same electrochemical coupling conditions when modulating the same channel. This significantly improves the consistency of multi-gate signal response and enhances the overall detection stability and accuracy of the device. Based on this equidistant multi-gate structure, this invention can simultaneously achieve sensitive and specific detection of multiple biomarkers, meeting the needs of in-situ monitoring of multiple indicators in complex biological samples. In the OECT single-channel multi-gate structure, a single conductive channel composed of PEDOT:PSS is synergistically modulated with the three gates to detect three types of BCAAs. Each gate modulates the channel carrier concentration through ion implantation-doping. When BCAAs enter and bind to the MIP recognition cavity, they alter the ion channels, charge environment, and PB redox current at the gate interface. These interfacial changes are rapidly propagated to the channel through the highly conductive LIG–MXene network, modulating the doping-dedoping degree of PEDOT:PSS and ultimately causing source-drain current (Id). ds Significant changes in the signal. Utilizing the multi-gate signal amplification effect of OECT, this invention can efficiently convert weak interface signals into measurable currents, enabling rapid, sensitive, and specific detection of three non-electroactive BCAAs.

[0031] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0032] 1. High sensitivity and specificity detection: This invention uses a LIG–MXene-PB-MIP composite electrode, which, through the electrochemical coupling and signal amplification mechanism of multi-gate single-channel OECT, converts the specific binding of non-electroactive small molecules BCAAs in the MIP layer into a measurable current signal, thereby achieving high sensitivity and high selectivity detection.

[0033] 2. Multi-index simultaneous detection capability: The single-channel multi-gate structure enables parallel monitoring of multiple target molecules, including leucine, isoleucine and valine, while maintaining signal stability and accuracy;

[0034] 3. Fast response: The flexible substrate and the efficient ion-electron coupling mechanism of the gate-channel enable interface changes to be converted into significant source-drain current changes in a short time;

[0035] 4. High integration and easy fabrication: The source, drain and channel are precisely patterned through photolithography, and multiple gates are distributed around a single channel. The overall device structure is compact, which is convenient for integrated design and suitable for multi-throughput detection or wearable sensing systems. Moreover, the device structure is miniaturized and flexible, which can realize wearable or skin-touch real-time monitoring.

[0036] 5. Wide range of applications: The sensor of this invention can be used for in-situ rapid detection of most amino acids, sugars, cholesterol and other non-electroactive small molecules and biomarkers, and is suitable for a variety of applications such as health monitoring, disease screening and personalized medicine. Attached Figure Description

[0037] Figure 1 This is a structural diagram of the flexible multi-gate single-channel organic electrochemical transistor molecularly imprinted sensor of the present invention;

[0038] (a) is a schematic diagram, and (b) is a physical image.

[0039] Figure 2 This diagram illustrates the flexibility of the flexible multi-gate single-channel organic electrochemical transistor molecularly imprinted sensor of this invention.

[0040] Figure 3 This is a schematic diagram of the fabrication process of the LIG-MXene-PB-MIP multilayer composite electrode for the sensor of the present invention.

[0041] Figure 4 For [Fe(CN)6] 3- / 4- Cyclic voltammetry (CV) curves of LIG electrode, LIG-PB-MIP electrode and LIG-MXene-PB-MIP electrode measured in redox system.

[0042] Figure 5 The image shows the MIP polymerization and elution comparison before and after the molecularly imprinted electrode.

[0043] Among them, (a) is the cyclic voltammetry (CV) curve of the MIP deposition process, and (b) is the comparison of the current response before and after elution.

[0044] Figure 6 Cyclic voltammetry (CV) curves of PB and MXene-modified electrodes;

[0045] Figure (a) shows the CV curves under different PB deposition amounts, and Figure (b) shows the CV curves under different MXene material modification amounts.

[0046] Figure 7 The image shows the test results and normalized response curves of the flexible multi-gate single-channel organic electrochemical transistor molecularly imprinted sensor of this invention for three branched amino acids.

[0047] Among them, (a), (b), and (c) are the test results and normalized response curves of valine, (d), (e), and (f) are the test results and normalized response curves of leucine, and (g), (h), and (i) are the test results and normalized response curves of isoleucine. Detailed Implementation

[0048] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments and accompanying drawings.

[0049] A flexible multi-gate single-channel OECT molecular imprinted sensor, the structure of which is as follows: Figure 1 As shown, it includes a flexible substrate, and a source, a drain, and three gates disposed on the surface of the substrate;

[0050] The source and drain have similar structures, each consisting of an arc, a long rectangular strip, and a rectangular block. One end of the long rectangular strip is connected to the arc, and the other end is connected to the rectangular block. The arcs of the source and drain are distributed vertically and do not touch each other. The centers of the two arcs are located on the same side of the arc, and the diameters and lengths of the two arcs are different. The fan-shaped area formed between them serves as the channel area. The channel is formed by PEDOT:PSS covering this channel area.

[0051] Three gates are evenly distributed around the source and drain. Each gate includes a fan-shaped sensing region, a metal connection line connected to the fan-shaped sensing region, and a rectangular block. The distances from the center of the inner arc of the three fan-shaped sensing regions to the center of the inner arc of the channel fan are equal.

[0052] The fan-shaped sensing region of the gate is a laser-induced graphene electrode functionalized with a molecularly imprinted polymer film, which is then modified with Prussian blue (PB) to serve as a redox probe.

[0053] Figure 2 This demonstrates the flexibility of the sensor of the present invention, showing that the device can maintain its complete structure under bending deformation conditions, reflecting its good mechanical compliance and wearable application adaptability.

[0054] Example 1

[0055] A method for fabricating a flexible multi-grid single-channel OECT sensor includes the following steps:

[0056] Step 1. Fabrication of OECT transistors:

[0057] Step 1.1. Fix the PI film onto the glass plate;

[0058] Step 1.2. Fabricate a patterned mask on the PI film surface using photolithography: First, spin-coat AZ5214 photoresist onto the PI surface, sequentially at 1000 r / min for 10 s and 3000 r / min for 30 s to form a uniform photoresist layer; then pre-bake on a 100 ℃ heating stage for 60 s, followed by the first exposure for 4 s, then post-bake at 120 ℃ for 90 s, and complete the second exposure for 40 s; finally, place the PI film in a developer solution for 40 s to remove the photoresist in the non-patterned areas, thereby obtaining the desired patterned mask structure;

[0059] Step 1.3. Au metal electrodes are deposited on a patterned mask using magnetron sputtering. To improve the adhesion between the gold film and the PI substrate, a titanium layer is first deposited on the substrate surface as an adhesion layer using radio frequency magnetron sputtering. The sputtering power is set to 200 W, and after pre-sputtering for 10 min, deposition continues for another 5 min under the same conditions. Subsequently, a gold film is deposited on the titanium layer using DC magnetron sputtering at a sputtering power of 50 W for 6 min, thus forming the source and drain structures. The completed sample is then immersed in acetone to remove the photoresist, yielding the patterned source and drain electrodes.

[0060] Step 1.4. Spin-coat the entire substrate surface with PEDOT:PSS solution under the following conditions: spin-coat at 500 r / min for 6 s, followed by spin-coat at 2500 r / min for 30 s to form a uniform PEDOT:PSS layer; after completion, anneal at 120 ℃ for 60 min.

[0061] The PEDOT:PSS solution comprises: 94 wt% PEDOT:PSS (PH-1000), 5 wt% ethylene glycol, 1 wt% 3-glycidyl etheroxypropyltrimethoxysilane, and 0.1 wt% dodecylbenzenesulfonic acid;

[0062] Step 1.5. Photolithography is performed on the channel region between the source and drain electrodes using AZ6112 photoresist. A uniform photoresist film is formed by spin-coating at 1000 r / min for 10 s and 3000 r / min for 30 s. The film is then soft-baked at 100 ℃ for 60 s, followed by exposure for 4 s and development in a developer for 45 s to obtain a fan-shaped photoresist mask covering the channel region. Using this mask as a protective layer, the exposed PEDOT:PSS film is removed by oxygen plasma etching (power 200 W, etching for 240 s). Finally, the device is immersed in acetone to remove the photoresist, thus forming the PEDOT:PSS conductive channel.

[0063] Step 1.6. Use a CO2 laser to perform local laser carbonization on the gate region of the PI film, causing the surface to undergo laser-induced carbonization and transform into a graphene structure, thereby obtaining the three gate LIG patterns required.

[0064] Step 1.7. Encapsulate the transistor device using SU-8 photoresist: First, perform a two-step spin coating on the substrate surface, specifically spin coating at 1000 r / min for 10 s, followed by spin coating at 5000 r / min for 30 s; after spin coating, pre-bake by heating at 65 ℃ for 2 min and 95 ℃ for 5 min respectively; then, expose the photoresist layer to ultraviolet light for 30 s; after exposure, post-bake by heating at 65 ℃ for 2 min and 95 ℃ for 5 min; finally, place the device in a developer solution for 3 min 30 s to remove the photoresist in non-patterned areas, thereby obtaining a patterned package structure defining the channel, source, drain, and three gate exposure areas;

[0065] Step 2. Perform LIG sector-shaped sensing area modification, the modification process is as follows: Figure 3 As shown;

[0066] Step 2.1. Modifying MXene material

[0067] Titanium carbide (Ti3C2T) was modified into the LIG sensing layer using a drop-coating method. x MXene material; the concentration of the MXene dispersion used was 5 mg / mL, which was uniformly added dropwise to the LIG sector sensing area and allowed to dry naturally;

[0068] Step 2.2. Deposition of Prussian blue redox probe layer

[0069] Step 2.2.1. Prepare the PB electrochemical deposition solution by adding 3 mM ferric chloride (FeCl3), 3 mM potassium ferricyanide (K3Fe(CN)6), 0.1 M hydrochloric acid (HCl) and 0.1 M potassium chloride (KCl) to deionized water and stirring until all components are completely dissolved. The resulting solution is used as the PB deposition solution.

[0070] Step 2.2. PB is deposited in the gate sensing region using cyclic voltammetry. The fan-shaped gate region is immersed in PB deposition solution, and cyclic scanning is performed at a scan rate of 50 mV / s in the potential range of -0.2 V to 0.6 V to form a uniform PB redox probe layer.

[0071] Step 2.3. Deposit MIP molecularly imprinted layer

[0072] Step 2.3.1. Prepare the MIP electropolymerization solution. The polymerization solution is prepared by dissolving 5 mM template (valine, leucine, and isoleucine), 12.5 mM 3-aminophenylboronic acid (APBA), and 37.5 M pyrrole in 0.01 M, pH 6.5 phosphate buffer solution (PBS) and mixing thoroughly. Among them, 3-aminophenylboronic acid (APBA) is used as a functional monomer, and its phenylboronic acid group binds to the template molecule through reversible interaction to construct imprinted holes with high specificity. Pyrrole is used as the main polymerization monomer, which forms a conductive and structurally stable polypyrrole (PPy) backbone during electrochemical polymerization, providing mechanical support and electronic conduction pathways for the molecular imprinted layer.

[0073] Step 2.3.2. Electropolymerization of MIP molecular imprinted layer: Immerse the gate sensing part in MIP electropolymerization deposition solution, and deposit MIP thin film in the required area using cyclic voltammetry. The potential range is set to 0 V to 1 V, the scan rate is 50 mV / s, and the number of cycles is 10 to form a molecular imprinted polymer layer.

[0074] Step 2.2.4. Template molecule removal

[0075] The molecularly imprinted electrode was immersed in a mixed solution of acetic acid and methanol at a volume ratio of 7:3 for 1 hour to remove template molecules from the MIP film. During this process, the acetic acid and methanol mixed solution disrupted the reversible interaction between the template molecules and the functional monomers, causing the template molecules to be released from the polymer network. This resulted in the formation of specific recognition holes in the film that are complementary to the shape and functional groups of the template molecules, providing highly selective binding sites for subsequent target molecule recognition.

[0076] A flexible OECT molecular imprinted sensor based on a multi-gate single channel has been successfully fabricated.

[0077] To verify the performance and specifications of the flexible OECT molecular imprinted sensor based on a multi-gate single channel prepared in this invention, its sensing performance was investigated using various electrochemical detection methods.

[0078] Figure 4 For 5mM [Fe(CN)6] 3- / 4- In solution, characteristic curves were obtained by cyclic voltammetry (CV) tests on three different electrodes: LIG, LIG-PB-MIP, and LIG-MXene-PB-MIP, using a three-electrode system. The test conditions were: potential scan range −0.2 V to 0.6 V, scan rate 50 mV / s; the electrode of this invention was used as the working electrode (WE), the platinum wire as the counter electrode (CE), and the silver / silver chloride electrode as the reference electrode (RE). Clear Fe was observed in all of the obtained CV curves. 2+ / Fe 3+ The redox peaks were observed, with the redox peak current of the LIG-MXene-PB-MIP electrode being significantly higher than that of the LIG-PB-MIP and unmodified LIG electrodes. This result indicates that the introduction of MXene effectively improves the specific surface area and electrochemical activity of the electrode, thereby enhancing its redox reaction capability. This further demonstrates that the LIG-MXene-PB-MIP electrode of the present invention has superior electrochemical performance and can exhibit a higher current response, thus enabling efficient detection of BCAAs.

[0079] Figure 5 This section presents the electrochemical deposition process of MIP molecularly imprinted polymers and the comparison results before and after template elution; among them, Figure 5 (a) shows the cyclic voltammetry (CV) curves obtained during the MIP electropolymerization process. As the number of cycles increases, the current gradually decreases, indicating that the monomers continuously undergo oxidative polymerization on the electrode surface and form a dense molecularly imprinted polymer film, which hinders electron transfer at the electrode interface and reduces the current response, thus proving that the MIP film has been successfully deposited. Figure 5 (b) is a comparison of the CV current obtained before and after elution of the electrode in 0.1 M KCl solution (test conditions: three-electrode system, scan potential −0.2 V~0.6 V, scan rate 50 mV / s). The current after elution is higher than that before elution. This is because the elution process removes the template molecules from the polymer network, and the imprinted sites originally occupied by the template are released, which makes more interconnected microporous structures form inside the MIP membrane and enhances the transport channels of ions and electrons, thereby weakening the interfacial impedance. This is manifested as a significant increase in current response. This change verifies the successful removal of template molecules and the formation of highly selective recognition sites in the sensor, which provides a guarantee for the accurate detection of target molecules in the future.

[0080] Figure 6 Figure 1 shows the data results obtained from the optimization experiment of PB and MXene modification conditions. (a) Figure 2 shows the CV curves under different PB deposition amounts, and (b) Figure 3 shows the CV curves under different MXene modification amounts. It can be seen from the figure that the optimal number of PB deposition cycles is 120-140, and the optimal modification amount of MXene material is 40-50 μL, with an MXene dispersion concentration of 5 mg / mL.

[0081] Figure 7 The image shows the test results and normalized response curves of the flexible multi-gate single-channel organic electrochemical transistor molecular imprinted sensor of this invention for three branched-chain amino acids (valine, leucine, and isoleucine). The results show that the effective detection range of valine is 1 μM to 400 μM, leucine is 1 μM to 350 μM, and isoleucine is 1 μM to 400 μM, all covering the physiological concentration range of these three amino acids in human body fluids. Each target molecule exhibits a good linear response relationship within the above range, indicating that the sensor of this invention can achieve high sensitivity, wide range, and quantitative detection of the three branched-chain amino acids. These results further verify that the constructed multi-gate molecular imprinted system has outstanding specific recognition ability and excellent electrochemical conversion performance, providing a reliable detection platform for the simultaneous analysis of multi-component amino acids.

[0082] The above description is merely a specific embodiment of the present invention. Any feature disclosed in this specification may be replaced by other equivalent or similar features unless otherwise specified. All disclosed features, or steps in all methods or processes, may be combined in any way except for mutually exclusive features and / or steps.

Claims

1. A flexible multi-grid single-channel OECT molecular imprinted sensor, characterized in that, The flexible multi-gate single-channel OECT molecular imprint sensor includes a flexible substrate, and a source, a drain, and three gates disposed on the surface of the substrate. The source and drain have similar structures, each consisting of an arc, a long rectangular strip, and a rectangular block. One end of the long rectangular strip is connected to the arc, and the other end is connected to the rectangular block. The arcs of the source and drain are distributed vertically and do not touch each other. The centers of the arcs are located on the same side of the arcs. The diameters and lengths of the two arcs are different, and the fan-shaped area formed between them serves as the channel region. The channel is formed by PEDOT:PSS covering this channel region. Three gates are evenly distributed around the source and drain. Each gate includes a fan-shaped sensing region, a metal connection line connected to the fan-shaped sensing region, and a rectangular block. The distance from the center of the three fan-shaped sensing regions to the center of the channel fan is equal. The fan-shaped sensing region of the gate is obtained by modifying PB with a laser-induced graphene electrode as a redox probe, and then modifying it with a molecularly imprinted polymer film.

2. The flexible multi-grid single-channel OECT molecular imprinting sensor as described in claim 1, characterized in that, The transistor channel is fan-shaped, and the ratio of its radial length to its arc length is (15-20):

1.

3. The flexible multi-grid single-channel OECT molecular imprint sensor as described in claim 1, characterized in that, Before modifying the redox probe, the fan-shaped sensing region of the gate is modified with MXene material.

4. A method for fabricating a flexible multi-gate single-channel OECT molecularly imprinted sensor, characterized in that, Includes the following steps: S1. Preparation of a flexible polyimide substrate; S2. Patterned source and drain electrodes are fabricated on the surface of a flexible substrate using a photolithography-magnetron sputtering process; S3. Preparation of fan-shaped PEDOT:PSS channels: A conductive polymer solution, PEDOT:PSS, is spin-coated onto the substrate surface and annealed. A photoresist pattern is then formed in the channel region between the source and drain electrodes. The PEDOT:PSS film not protected by the photoresist is selectively removed by plasma etching. Finally, the residual photoresist is removed by solvent washing, leaving PEDOT:PSS only in the designated connection region between the source and drain electrodes, thereby forming a conductive channel. S4. Three sector-shaped LIG gate electrodes were fabricated on the substrate using CO2 laser processing technology; S5. Modified PB was prepared on a sector-shaped LIG electrode by an electrochemical method to serve as a redox probe; S6. A molecularly imprinted polymer (MIP) capable of specifically recognizing BCAAs is prepared on a sector-shaped LIG-PB electrode to obtain the desired molecularly imprinted sensor.

5. The preparation method according to claim 4, characterized in that, In S3, the PEDOT:PSS solution consists of PEDOT:PSS, ethylene glycol, 3-glycidyl etheroxypropyltrimethoxysilane, and dodecylbenzenesulfonic acid.

6. The preparation method according to claim 4, characterized in that, Before modifying the redox probe on the gate surface in step S5, the LIG electrode is first modified with MXene material, which is prepared by drop coating.

7. The preparation method according to claim 6, characterized in that, The optimal amount of MXene material for modification is 40-50 microliters.

8. The preparation method according to claim 4, characterized in that, The electrochemical method in step S5 is cyclic voltammetry. The specific process is as follows: the LIG electrode is immersed in the PB deposition solution, and cyclic scanning is performed at a scan rate of 30-50 mV / s in the potential range of -0.2 V to 0.6 V. The number of cyclic deposition cycles is 120-140 cycles to form a uniform PB redox probe layer.

9. The preparation method according to claim 4, characterized in that, In step S6, the MIP electropolymerization solution is a solution composed of the test template, 3-aminophenylboronic acid, pyrrole, and phosphate buffer solution; the test template is valine, leucine, and isoleucine.

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