Ultrasensitive dual-mode biosensor based on organic field-effect transistors and its fabrication method

Abstract

This invention specifically relates to an ultrasensitive dual-mode biosensor based on organic field-effect transistors and its fabrication method, belonging to the field of biosensor technology. The sensor uses a blended thin film prepared from a conjugated polymer and copper / dysprosium bimetallic nanomaterials as the semiconductor layer. After modifying the film surface with specific antibodies, dual calibration of the target biomarker concentration is achieved by detecting changes in threshold voltage and source / drain current, significantly improving detection accuracy. The blended thin film prepared by this invention can effectively block H2O and O2 in the environment, improving the device's operational and storage stability; the dual-headed broom-like nanostructure enables ultrasensitive detection of the target biomarker; combined with dual-mode signal mutual calibration and machine learning algorithm analysis, the detection sensitivity and reliability are enhanced. This sensor has advantages such as label-free operation, speed, and simplicity, and has great application potential.

Description

Technical Field

[0001] This invention belongs to the field of biosensor technology, specifically relating to an ultrasensitive dual-mode biosensor based on organic field-effect transistors and its fabrication method. Background Technology

[0002] Field-effect transistor (FET) biosensors have shown great potential in the field of biomolecular detection due to their unique electrical response mechanism and ease of miniaturization and integration, especially for highly sensitive sensing of biomarkers such as proteins and nucleic acids. In recent years, FET biosensors based on organic semiconductor materials have attracted widespread attention in flexible electronics and wearable sensing due to their material flexibility, good biocompatibility, and solution-processability. However, traditional FET biosensors often rely on a single electrical signal (such as threshold voltage or current change) for detection, making them susceptible to interference from non-specific adsorption and environmental noise in complex biological samples, leading to insufficient detection accuracy and reliability. Dual-mode FET biosensors, through dual signal response detection, can significantly improve detection accuracy and sensing reliability. They are also relatively simple to operate, have low background signal, and some sensors do not require labeling or the use of commercially available oxidases, resulting in lower production costs. Furthermore, they facilitate the development of portable devices suitable for on-site and point-of-care testing. Summary of the Invention

[0003] In view of this, there is an urgent need to provide an ultrasensitive dual-mode biosensor that integrates stability, high sensitivity and high reliability, as well as its preparation method, to solve the problems of existing biosensors being complex to operate, costly, dependent on labeling, and lacking reliability due to single detection modes.

[0004] This invention creatively blends conjugated polymers with specially formulated double-headed, broom-shaped copper / dysprosium bimetallic nanomaterials to develop a novel functionalized thin film material. The material's unique "three-system synergy" structure allows it to function as the semiconductor layer in organic field-effect transistors while the transition metal Cu exhibits variable valence states (e.g., Cu...). + / Cu 2+ The lanthanide metal Dy has good thermal and chemical stability, and after doping, it can passivate the surface states of semiconductors and improve the sensing performance of devices. The conjugated polymer PDBT-co-TT alkyl chain can effectively block H2O and O2 molecules in the environment from entering the device, thereby fundamentally improving the operational stability and long-term storage stability of the device and overcoming the inherent defects of poor environmental stability of organic semiconductors.

[0005] To achieve the above objectives, the technical solution of the present invention is as follows:

[0006] In a first aspect, the present invention discloses an ultrasensitive dual-mode biosensor based on organic field-effect transistors, comprising:

[0007] A dual-mode field-effect transistor, wherein the dual-mode field-effect transistor comprises, from bottom to top, a substrate, a gate, a dielectric layer, a semiconductor layer, and a source and a drain disposed on the semiconductor layer;

[0008] And, capture antibodies immobilized on the surface of the semiconductor layer for specifically binding to target biomarkers;

[0009] The semiconductor layer is a blended thin film made by blending the conjugated polymer PDBT-co-TT with copper / dysprosium bimetallic nanomaterials with a double-headed broom-like structure.

[0010] Furthermore, the volume ratio of the conjugated polymer PDBT-co-TT to the copper / dysprosium bimetallic nanomaterial in the blended film is (1-10):(1-5), specifically 1:5, 1:2, 1:1, 2:1, 5:1, 8:1 and 10:1.

[0011] Furthermore, the conjugated polymer PDBT-co-TT is synthesized via a Stieler coupling reaction at a temperature of 80-160℃ for a time of 48-96 h; the copper / dysprosium bimetallic nanomaterial is prepared by a hydrothermal method from copper chloride dihydrate and dysprosium nitrate pentahydrate in the presence of polyvinylpyrrolidone, ascorbic acid, and 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid.

[0012] Furthermore, the method for preparing the blended film is as follows: a chlorobenzene solution of the conjugated polymer PDBT-co-TT is mixed with an ethanol solution of the copper / dysprosium bimetallic nanomaterial at room temperature, followed by ultrasonication or stirring for ≥1 h.

[0013] Furthermore, the source and drain are electrically connected to the semiconductor layer, and the width-to-length ratio of the channel region between the source and drain is (8-20):1.

[0014] Furthermore, the target biomarker is the TFF3 protein.

[0015] Secondly, this invention discloses a method for preparing the aforementioned ultrasensitive dual-mode biosensor, comprising the following steps:

[0016] (1) Substrate treatment: Provide a substrate and perform OTS modification on the SiO2 dielectric layer on its surface for 3-6 hours;

[0017] (2) Electrode preparation: The source and drain electrodes that are electrically connected to the semiconductor layer are prepared by mask evaporation. The pattern of the mask forms a channel region with a width-to-length ratio of (8-20):1 between the source and drain electrodes. The evaporation rate is 0.1-0.8 Å / s and the evaporation thickness is 20-50 nm.

[0018] (3) Semiconductor layer preparation: The blend solution of conjugated polymer PDBT-co-TT and copper / dysprosium bimetallic nanomaterials is spin-coated onto the channel region between the source and drain electrodes to form a semiconductor layer; the spin-coating speed is 1500-3500 rpm and the spin-coating time is 20-40 s;

[0019] (4) Annealing treatment: Anneal the prepared device at a temperature of 170-190℃ for 10-20 min.

[0020] (5) Antibody immobilization: The captured antibody is immobilized on the surface of the semiconductor layer.

[0021] Most importantly, the technical solution provided by this invention achieves both material and structural innovation. The prepared biosensor not only possesses ultra-high detection sensitivity at the femtomolar level and excellent stability, but the entire sensing system also has the advantages of being label-free, easy to operate, fast-responding, and low-cost.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] (1) This invention provides a unique composite system composed of functionalized bi-headed broom-shaped copper / dysprosium bimetallic nanomaterials and conjugated polymers. This composite system can be used to construct sensing interfaces, achieving efficient and non-destructive immobilization of biorecognition molecules, thereby enabling ultrasensitive detection of target analytes. This structure effectively enhances the activity of the sensing interface, significantly improves the carrier mobility and operational stability of the thin film, suppresses external environmental interference, and provides a new material strategy for the development of high-performance dual-mode field-effect transistor sensors.

[0024] (2) This invention uses the semiconductor layer modified with the above-mentioned composite thin film material as the core to construct a dual-mode field-effect transistor biosensor. This sensor fully utilizes the multi-signal output characteristic of the device, simultaneously monitoring the threshold voltage change ΔV of the transfer curve. TH With the change in source-drain current ΔI DSThis system enables quantitative analysis of target analyte concentrations. Dual-signal synchronous output and cross-validation effectively overcome reliability issues caused by environmental noise or system drift in single-signal detection. Both electrical signals exhibit excellent linear response within their detection range, with detection limits reaching the femtomolar level, demonstrating ultra-high sensitivity. The entire sensing system offers advantages such as label-free operation, rapid response, and ease of use.

[0025] (3) This invention further combines the response data obtained from multiple detections with various machine learning algorithm models (such as random forest, gradient boosting, support vector machine, and neural network) to achieve auxiliary analysis and reliability verification of the detection results, significantly improving the accuracy, repeatability, and anti-interference ability of the system. Compared with existing sensing technologies, this invention can achieve high-precision and high-reliability detection at lower concentrations. Its detection limit is significantly lower than the threshold level of conventional methods, enabling the sensor to have high sensitivity, excellent stability, and long-term reliability, providing an effective technical tool for the accurate detection of ultra-trace biomolecules. Attached Figure Description

[0026] Figure 1 This is a flowchart illustrating the fabrication process of the dual-mode field-effect transistor of the present invention.

[0027] Figure 2 This is a synthetic route diagram for the copper / dysprosium bimetallic nanomaterials of this invention;

[0028] Figure 3 This is a high-resolution transmission electron microscope image of the copper / dysprosium bimetallic nanomaterial prepared in Example 5 of the present invention;

[0029] Figure 4 This is a synthetic route diagram of PDBT-co-TT of the present invention;

[0030] Figure 5 (a) is an environmental field emission scanning electron microscope cross-sectional image of PDBT-co-TT prepared in Example 5 of the present invention, and (b) is an environmental field emission scanning electron microscope cross-sectional image of PDBT-co-TT and copper / dysprosium bimetallic nanomaterial blend film prepared in Example 5 of the present invention.

[0031] Figure 6 (a) is a metallographic microscopy image of PDBT-co-TT prepared in Example 5 of the present invention, (b) is a metallographic microscopy image of copper / dysprosium bimetallic nanomaterial prepared in Example 5 of the present invention, and (c) is a metallographic microscopy image of the PDBT-co-TT and copper / dysprosium bimetallic nanomaterial blend film prepared in Example 5 of the present invention.

[0032] Figure 7 The image shows the X-ray photoelectron spectroscopy (XPS) image of the PDBT-co-TT blend film with copper / dysprosium bimetallic nanomaterials prepared in Example 5 of this invention.

[0033] Figure 8 The gel chromatography curve of PDBT-co-TT prepared in Example 1 of this invention;

[0034] Figure 9 (a) shows the on / off ratio error of the PDBT-co-TT and copper / dysprosium bimetallic nanomaterials of the present invention under different blending ratios, and (b) shows the carrier mobility error of the PDBT-co-TT and copper / dysprosium bimetallic nanomaterials of the present invention under different blending ratios.

[0035] Figure 10 (a) shows the contact angle variation curves of PDBT-co-TT and copper / dysprosium bimetallic nanomaterials of the present invention under different blending ratios, and (b) shows the surface energy variation curves of PDBT-co-TT and copper / dysprosium bimetallic nanomaterials of the present invention under different blending ratios.

[0036] Figure 11 (a) is the transfer curve of the dual-mode field-effect transistor under the optimal blending ratio of the present invention, and (b) is the output curve of the dual-mode field-effect transistor under the optimal blending ratio of the present invention.

[0037] Figure 12 (a) is a graph showing the relative voltage-current change trend of the PDBT-co-TT prepared in Example 5 over 48 hours, and (b) is a graph showing the relative voltage-current change trend of the PDBT-co-TT and copper / dysprosium bimetallic nanomaterial blend thin film device prepared in Example 5 over 48 hours.

[0038] Figure 13 (a) shows the on / off ratio change rate of the PDBT-co-TT and its blended thin film device with copper / dysprosium bimetallic nanomaterials prepared in Example 5 during 30 consecutive repeated operations; (b) shows the source-drain current change curve of the PDBT-co-TT and its blended thin film device with copper / dysprosium bimetallic nanomaterials prepared in Example 5 during 30 consecutive repeated operations.

[0039] Figure 14 (a) and (b) are atomic force microscopy images of the surface morphology of the dual-mode biosensor before and after grafting TFF3 antibody, respectively; (c) and (d) are cross-sectional height images of the dual-mode biosensor before and after grafting TFF3 antibody, respectively.

[0040] Figure 15 This is a flowchart illustrating the fabrication process of the dual-mode biosensor of the present invention.

[0041] Figure 16 In the middle, (a) and (b) are the dual-signal response diagrams of the threshold voltage change and the source-drain current change detected in TFF3 solutions of different concentrations, respectively;

[0042] Figure 17 In the middle (a) and (b), the response diagrams of the threshold voltage change and the source-drain current change in the protein specificity selection test are respectively.

[0043] Figure 18 This is an auxiliary verification diagram for the dual-mode biosensor detecting TFF3 using dual-signal response data combined with four models of machine learning algorithms.

[0044] Figure description: In the figure, Cu / Dy@NM represents "copper / dysprosium bimetallic nanomaterial"; PDBT-co-TT + Cu / Dy@NM represents "PDBT-co-TT blended with copper / dysprosium bimetallic nanomaterial thin film". Detailed Implementation

[0045] The technical solutions of the embodiments of the present invention will be clearly, thoroughly, and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0046] The sources of the instruments and reagents used in the embodiments of this invention are shown in Table 1. Unless otherwise specified, they are all conventional biochemical reagents; the experimental methods described are all conventional methods unless otherwise specified.

[0047] Table 1. Reagents or Instruments and Their Sources of Purchase

[0048]

[0049] In this embodiment of the invention, the field-effect transistor device fabrication system was purchased from Shenzhen Vector Scientific Instruments Co., Ltd. FS380-S8, and an INFICON SQC-310C film thickness gauge was used. The film thickness accuracy error is within ±0.01 Å / s, and the readings of 4 film thickness probes can be displayed.

[0050] Example 1

[0051] 1.1 Preparation of PDBT-co-TT

[0052] Under a nitrogen atmosphere, 200 mg of 2,5-bis-(trimethyltinyl)thieno[3,2-b]thiophene (TH289), 4 mg of tris(o-methylphenyl)phosphine, 200 mg of 3,6-bis-(5-bromothiophene-2-yl)-2,5-bis-(2-octyl-1-dodecyl)pyrrolo[3,4-c]pyrrole-1,4-dione (DPP38), 4 mg of tris(dibenzylacetone)dipalladium, and 20 mL of ultra-dry chlorobenzene were added to a Shrek flask. The mixture was stirred at 80 °C for 36 h, and 0.3 mL of bromobenzene was added 1 h before the end of the reaction to terminate the reaction. The reaction solution was poured into 200 mL of methanol containing 8 mL of concentrated hydrochloric acid to precipitate the precipitate, and then purified by Soxhlet extraction with 200 mL of methanol, 200 mL of ethyl acetate, and 200 mL of chloroform. After extraction and purification, the extract was concentrated by rotary evaporation with chloroform, methanol was added to precipitate the polymer, and the precipitate was filtered through an organic microporous membrane. The filtered polymer was then dried in a vacuum oven at 60°C for 24 h to obtain PDBT-co-TT.

[0053] 1.2 Synthesis of Copper / Dysprosium Bimetallic Nanomaterials

[0054] 10 g of polyvinylpyrrolidone was dissolved in 300 mL of ultrapure water, and 400 mg of copper chloride dihydrate and 450 mg of dysprosium nitrate pentahydrate were added. The mixture was stirred for 30 min at 60 °C under nitrogen protection. 20 mL of 2M NaOH was added and stirred for 10 min, followed by 20 mL of 1M ascorbic acid and stirring for 15 min. Finally, 5 mL of 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid was added, and stirring continued for 7 h. The reaction mixture was centrifuged, and the precipitate was washed several times alternately with ethanol and water, dried at 60 °C for at least 24 h, and then ground to obtain nanomaterial powder.

[0055] 1.3 Preparation of a blend solution of PDBT-co-TT and copper / dysprosium bimetallic nanomaterials (volume ratio 1:5)

[0056] 25 mg of PDBT-co-TT was dissolved in 5 mL of chlorobenzene and stirred at 100 °C for 8 h to obtain a 5 mg / mL solution, which was then filtered through 0.22 μm nylon 6. 25 mg of nanomaterial powder was dissolved in 5 mL of ethanol and sonicated for 3 h to obtain a 5 mg / mL dispersion. The two were mixed at a volume ratio of 1:5 (polymer:nanomaterial) and sonicated for 30 min to obtain a blended solution of PDBT-co-TT and copper / dysprosium bimetallic nanomaterials.

[0057] 1.4 Fabrication of Dual-Mode Field-Effect Transistors

[0058] A dual-mode field-effect transistor was fabricated using the blended solution prepared in step 1.3 as the semiconductor layer material. The structure and fabrication process of this device are as follows: Figure 1As shown, the structure includes: a silicon substrate with a SiO2 dielectric layer, an OTS-modified interface layer, vapor-deposited Au source / drain electrodes, and a spin-coated PDBT-co-TT / bimetallic nanomaterial blend thin-film semiconductor layer. The specific fabrication steps are as follows:

[0059] (1) Substrate treatment (OTS modification): A heavily doped silicon wafer (gate) and a 300 nm thick thermally grown SiO2 layer (dielectric layer) on its surface were used as the substrate. First, the silicon wafer was ultrasonically cleaned sequentially with ultrapure water, ethanol, and isopropanol for 30 min each, and then dried with nitrogen. Subsequently, oxygen plasma treatment (power 20 W, oxygen flow rate 0.1-1.5 mbar, time 10 min) was performed to activate the surface. OTS solution (20 μL) was added to n-heptane (10 mL) and ultrasonicated for 5 min to obtain the modification solution. The silicon wafer was immersed in this solution and allowed to stand at room temperature for 3 h to perform OTS self-assembled monolayer modification, so that a uniform hydrophobic layer was formed on the SiO2 surface. After removal, it was rinsed sequentially with n-heptane and isopropanol, and then dried with nitrogen for later use. This OTS layer can optimize the interface contact between the dielectric layer and the semiconductor layer and improve the electrical performance of the device.

[0060] (2) Electrode fabrication (mask evaporation): On the substrate treated in step (1), a mask is accurately attached, and the channel width-to-length ratio is set to 8:1. Gold electrodes are deposited on the silicon wafer at a rate of 0.1 Å / s using an inorganic evaporator, and the final film thickness is controlled to be 20 nm. After evaporation, the mask is removed to obtain the source and drain electrodes with precise structures.

[0061] (3) Semiconductor layer preparation (spin coating): Take 50 μL of the blend solution (PDBT-co-TT chlorobenzene solution and bimetallic nanomaterial-ethanol solution prepared according to the proportion of this embodiment) with a pipette and evenly cover the entire silicon wafer surface, ensuring that there are no air bubbles. Set the spin coating speed to 3000 rpm and the spin coating time to 40 s. After spin coating is completed, remove the silicon wafer and store it properly.

[0062] (4) Annealing treatment: To remove residual chlorobenzene solvent and improve the smoothness of the polymer film, the spin-coated silicon wafer was annealed. The heating stage temperature was set to 170°C, and the spin-coated device was placed on the heating stage and kept for 10 min. After annealing, the silicon wafer was removed and stored for later use.

[0063] Example 2

[0064] 2.1 Preparation of PDBT-co-TT: Under a nitrogen atmosphere, 1000 mg of 2,5-bis-(trimethyltinyl)thieno[3,2-b]thiophene (TH289), 20 mg of tris(o-methylphenyl)phosphine, 1000 mg of 3,6-bis-(5-bromothiophene-2-yl)-2,5-bis-(2-octyl-1-dodecyl)pyrrolo[3,4-c]pyrrole-1,4-dione (DPP38), 20 mg of tris(dibenzylacetone)dipalladium, and 100 mL of ultra-dry chlorobenzene were added to a Shrek flask. The mixture was stirred at 130 °C for 48 h, and the reaction was terminated by adding 1.0 mL of bromobenzene 1 h before the end of the reaction. The reaction solution was poured into 1000 mL of methanol containing 40 mL of concentrated hydrochloric acid to precipitate the precipitate, which was then purified by Soxhlet extraction with 200 mL of methanol, 200 mL of ethyl acetate, and 200 mL of chloroform. After extraction and purification, the extract was concentrated by rotary evaporation with chloroform, methanol was added to precipitate the polymer, and the precipitate was filtered through an organic microporous membrane. The filtered polymer was then dried in a vacuum oven at 80°C for 24 h to obtain PDBT-co-TT.

[0065] 2.2 Synthesis of copper / dysprosium bimetallic nanomaterials:

[0066] 30 g of polyvinylpyrrolidone was dissolved in 800 mL of ultrapure water. 1400 mg of copper chloride dihydrate and 2000 mg of dysprosium nitrate pentahydrate were added, and the mixture was stirred for 50 min at 60 °C under nitrogen protection. 50 mL of 2M NaOH was added and stirred for 5 min, followed by 50 mL of 1M ascorbic acid and stirring for 20 min. Finally, 10 mL of 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid was added, and stirring continued for 8 h. The reaction mixture was centrifuged, and the precipitate was washed several times alternately with ethanol and water, dried at 60 °C for at least 48 h, and then ground to obtain nanomaterial powder.

[0067] 2.3 Preparation of a blend solution of PDBT-co-TT and copper / dysprosium bimetallic nanomaterials (volume ratio 1:2):

[0068] 50 mg of PDBT-co-TT was dissolved in 10 mL of chlorobenzene and stirred at 100 °C for 16 h to obtain a 5 mg / mL solution, which was then filtered through 0.22 μm nylon 6. 100 mg of the nanomaterial powder was dissolved in 20 mL of ethanol and sonicated for 5 h to obtain a 5 mg / mL dispersion. The two were then mixed at a volume ratio of 1:2 (polymer:nanomaterial) and sonicated for 1 h to obtain a co-mixed solution of PDBT-co-TT and copper / dysprosium bimetallic nanomaterials.

[0069] 2.4 Fabrication of Dual-Mode Field-Effect Transistors

[0070] (1) Substrate treatment (OTS modification): A heavily doped silicon wafer (gate) and a 300 nm thick thermally grown SiO2 layer (dielectric layer) on its surface were used as the substrate. First, the silicon wafer was ultrasonically cleaned sequentially with ultrapure water, ethanol, and isopropanol for 30 minutes each, and then dried with nitrogen. Subsequently, oxygen plasma treatment (power 20 W, oxygen flow rate 0.1-1.5 mbar, time 10 min) was performed to activate the surface. OTS solution (20 μL) was added to n-heptane (10 mL) and ultrasonically treated for 5 min to obtain the modification solution. The silicon wafer was immersed in this solution and allowed to stand at room temperature for 3 h to perform OTS self-assembled monolayer modification, so that a uniform hydrophobic layer was formed on the SiO2 surface. After removal, it was rinsed sequentially with n-heptane and isopropanol, and then dried with nitrogen for later use. This OTS layer can optimize the interface contact between the dielectric layer and the semiconductor layer and improve the electrical performance of the device.

[0071] (2) Electrode fabrication (mask evaporation): On the substrate treated in step (1), a mask is accurately attached, and the channel width-to-length ratio is set to 20:1. Gold electrodes are deposited on the silicon wafer at a rate of 0.4 Å / s using an inorganic evaporator, and the final film thickness is controlled to be 25 nm. After evaporation, the mask is removed to obtain the source and drain electrodes with precise structures.

[0072] (3) Semiconductor layer preparation (spin coating): Take 80 μL of the blend solution (PDBT-co-TT chlorobenzene solution and bimetallic nanomaterial-ethanol solution prepared according to the proportion of this embodiment) with a pipette and evenly cover the entire silicon wafer surface, ensuring that there are no air bubbles. Set the spin coating speed to 2500 rpm and the spin coating time to 35 s. After spin coating is completed, remove the silicon wafer and store it properly.

[0073] (4) Annealing treatment: To remove residual chlorobenzene solvent and improve the smoothness of the polymer film, the spin-coated silicon wafer was annealed. The heating stage temperature was set to 180°C, and the spin-coated device was placed on the heating stage and kept for 15 min. After annealing, the silicon wafer was removed and stored for later use.

[0074] Example 3

[0075] The difference between this embodiment and Embodiment 1 is that the volume ratio of the PDBT-co-TT and copper / dysprosium bimetallic nanomaterial blend solution is 1:1; the parameters for fabricating the dual-mode field-effect transistor are also different, as shown in 3.4, while the other steps are the same as in Embodiment 1.

[0076] 3.4 Fabrication of Dual-Mode Field-Effect Transistors

[0077] (1) Substrate treatment (OTS modification): A heavily doped silicon wafer (gate) and a 300 nm thick thermally grown SiO2 layer (dielectric layer) on its surface were used as the substrate. First, the silicon wafer was ultrasonically cleaned with ultrapure water, ethanol, and isopropanol for 5 h each, and then dried with nitrogen. Subsequently, oxygen plasma treatment (power 80 W, oxygen flow rate 0.1-1.5 mbar, time 40 min) was performed to activate the surface. OTS solution (100 μL) was added to n-heptane (10 mL) and ultrasonicated for 10 min to obtain the modification solution. The silicon wafer was immersed in this solution and allowed to stand at room temperature for 3 h to perform OTS self-assembly monolayer modification, so that a uniform hydrophobic layer was formed on the SiO2 surface. After removal, it was rinsed with n-heptane and isopropanol in sequence and dried with nitrogen for later use. This OTS layer can optimize the interface contact between the dielectric layer and the semiconductor layer and improve the electrical performance of the device.

[0078] (2) Electrode fabrication (mask evaporation): On the substrate treated in step (1), a mask is accurately attached, and the channel width-to-length ratio is set to 20:1. Gold electrodes are deposited on the silicon wafer at a rate of 0.6 Å / s using an inorganic evaporator, and the final film thickness is controlled to be 40 nm. After evaporation, the mask is removed to obtain the source and drain electrodes with precise structures.

[0079] (3) Semiconductor layer preparation (spin coating): Take 100 μL of the blend solution (PDBT-co-TT chlorobenzene solution and bimetallic nanomaterial-ethanol solution prepared according to the proportion of this embodiment) with a pipette and evenly cover the entire silicon wafer surface, ensuring that there are no air bubbles. Set the spin coating speed to 2000 rpm and the spin coating time to 30 s. After spin coating is completed, remove the silicon wafer and store it properly.

[0080] (4) Annealing treatment: To remove residual chlorobenzene solvent and improve the smoothness of the polymer film, the spin-coated silicon wafer was annealed. The heating stage temperature was set to 170°C, and the spin-coated device was placed on the heating stage and kept for 10 min. After annealing, the silicon wafer was removed and stored for later use.

[0081] Example 4

[0082] The difference between this embodiment and embodiment 3 is that the volume ratio of the PDBT-co-TT and copper / dysprosium bimetallic nanomaterial blend solution is 2:1; the semiconductor preparation (3) and annealing parameters (4) in the preparation of the dual-mode field-effect transistor are different, as shown in 4.4; the other steps are the same as in embodiment 3.

[0083] 4.4 Fabrication of Dual-Mode Field-Effect Transistors

[0084] (3) Semiconductor layer preparation (spin coating): Take 120 μL of the blend solution (PDBT-co-TT chlorobenzene solution and bimetallic nanomaterial-ethanol solution prepared according to the proportion of this embodiment) with a pipette and evenly cover the entire silicon wafer surface, ensuring that there are no air bubbles. Set the spin coating speed to 1500 rpm and the spin coating time to 35 s. After spin coating is completed, remove the silicon wafer and store it properly.

[0085] (4) Annealing treatment: To remove residual chlorobenzene solvent and improve the smoothness of the polymer film, the spin-coated silicon wafer was annealed. The heating stage temperature was set to 180°C, and the spin-coated device was placed on the heating stage and kept for 15 min. After annealing, the silicon wafer was removed and stored for later use.

[0086] Example 5

[0087] The difference between this embodiment and embodiment 3 is that the volume ratio of the PDBT-co-TT and copper / dysprosium bimetallic nanomaterial blend solution is 5:1; the semiconductor preparation (3) and annealing parameters (4) in the preparation of the dual-mode field-effect transistor are different, as shown in 5.4; the other steps are the same as in embodiment 3.

[0088] 5.4 Fabrication of Dual-Mode Field-Effect Transistors

[0089] (3) Semiconductor layer preparation (spin coating): Take 100 μL of the blend solution (PDBT-co-TT chlorobenzene solution and bimetallic nanomaterial-ethanol solution prepared according to the proportion of this embodiment) with a pipette and evenly cover the entire silicon wafer surface, ensuring that there are no air bubbles. Set the spin coating speed to 2000 rpm and the spin coating time to 30 s. After spin coating is completed, remove the silicon wafer and store it properly.

[0090] (4) Annealing treatment: To remove residual chlorobenzene solvent and improve the smoothness of the polymer film, the spin-coated silicon wafer was annealed. The heating stage temperature was set to 190°C, and the spin-coated device was placed on the heating stage and kept for 10 min. After annealing, the silicon wafer was removed and stored for later use.

[0091] Example 6

[0092] The difference between this embodiment and embodiment 3 is that the volume ratio of the PDBT-co-TT and copper / dysprosium bimetallic nanomaterial blend solution is 8:1; the semiconductor preparation (3) and annealing parameters (4) in the preparation of the dual-mode field-effect transistor are different, as shown in 6.4; the other steps are the same as in embodiment 3.

[0093] 6.4 Fabrication of Dual-Mode Field-Effect Transistors

[0094] (3) Semiconductor layer preparation (spin coating): Take 80 μL of the blend solution (PDBT-co-TT chlorobenzene solution and bimetallic nanomaterial-ethanol solution prepared according to the proportion of this embodiment) with a pipette and evenly cover the entire silicon wafer surface, ensuring that there are no air bubbles. Set the spin coating speed to 2500 rpm and the spin coating time to 30 s. After spin coating is completed, remove the silicon wafer and store it properly.

[0095] (4) Annealing treatment: To remove residual chlorobenzene solvent and improve the smoothness of the polymer film, the spin-coated silicon wafer was annealed. The heating stage temperature was set to 180°C, and the spin-coated device was placed on the heating stage and kept for 15 min. After annealing, the silicon wafer was removed and stored for later use.

[0096] Example 7

[0097] The difference between this embodiment and embodiment 3 is that the volume ratio of the PDBT-co-TT and copper / dysprosium bimetallic nanomaterial blend solution is 10:1; the semiconductor preparation (3) and annealing parameters (4) in the preparation of the dual-mode field-effect transistor are different, as shown in 7.4; the other steps are the same as in embodiment 3.

[0098] 7.4 Fabrication of Dual-Mode Field-Effect Transistors

[0099] (3) Semiconductor layer preparation (spin coating): Take 50 μL of the blend solution (PDBT-co-TT chlorobenzene solution and bimetallic nanomaterial-ethanol solution prepared according to the proportion of this embodiment) with a pipette and evenly cover the entire silicon wafer surface, ensuring that there are no air bubbles. Set the spin coating speed to 3000 rpm and the spin coating time to 30 s. After spin coating is completed, remove the silicon wafer and store it properly.

[0100] (4) Annealing treatment: To remove residual chlorobenzene solvent and improve the smoothness of the polymer film, the spin-coated silicon wafer was annealed. The heating stage temperature was set to 170°C, and the spin-coated device was placed on the heating stage and kept for 15 min. After annealing, the silicon wafer was removed and stored for later use.

[0101] Comparative Example 1

[0102] The preparation methods of the thin film material and field-effect transistor in Comparative Example 1 are the same as those in Example 1, except that the thin film material in this comparative example does not use copper / dysprosium bimetallic nanomaterial blending, and the semiconductor layer of the field-effect transistor uses pure PDBT-co-TT.

[0103] Test Example 1: Performance Characterization of Blended Thin Film Materials

[0104] This test example systematically characterizes the performance of the PDBT-co-TT blend film prepared in Example 5 with copper / dysprosium bimetallic nanomaterials, including morphology, structure, composition and film quality, to verify its comprehensive performance.

[0105] First, the present invention is based on Figure 2 The synthesis route of the copper / dysprosium bimetallic nanomaterials shown is used to prepare the nanomaterials, and the morphology of the copper / dysprosium bimetallic nanomaterials obtained in Example 5 is then observed using transmission electron microscopy. Figure 3 As shown, the nanomaterial exhibits a double-headed broom morphology with a fluffy surface, uniform size, and conforms to the expected structural design. Next, the above nanomaterial is combined with PDBT-co-TT (made from... Figure 4 The prepared synthetic route (as shown) was followed by blending, and the cross-sectional morphology of the blend film was characterized using ambient field emission scanning electron microscopy. Figure 5 As shown, the double-headed broom-shaped nanoparticles are uniformly dispersed in the polymer matrix and effectively encapsulated by PDBT-co-TT, indicating that the two have good compatibility and interfacial bonding.

[0106] To evaluate the macroscopic uniformity and surface quality of the blended films, a metallographic microscope was used to compare and observe the pure PDBT-co-TT film, the pure nanomaterial film, and the blended film prepared in Example 5. The results are as follows: Figure 6 As shown, the blended film has a smooth surface with no obvious agglomeration or phase separation, exhibiting excellent uniformity and film-forming properties, which meets the requirements of high-performance devices for film morphology.

[0107] Further qualitative analysis of the elemental composition of the blended thin film was performed using X-ray photoelectron spectroscopy. For example... Figure 7 As shown, characteristic peaks of Cu 2p and Dy 3d were clearly detected in the blend film, along with signals of C 1s, N 1s, O 1s, S 2p and P 2p, confirming that copper and dysprosium elements were successfully introduced and that the material is composed of multiple elements including Cu, Dy, C, N, O, S and P.

[0108] Furthermore, the molecular weight and distribution of the PDBT-co-TT synthesized in Examples 1-7 were determined by gel permeation chromatography, focusing on the polymer matrix itself. Test results using trichlorobenzene as solvent and at 150°C showed that the number-average molecular weight (Mn) of this series of polymers was [missing information]. n The energy density is approximately 53.4 kDa, and the dispersion (ε) is approximately 1.31 (see Example 1 for details). Figure 8 This indicates that the polymer has good purity and a concentrated molecular weight distribution, which meets the requirements for subsequent blending and device fabrication.

[0109] In summary, the PDBT-co-TT blended film with copper / dysprosium bimetallic nanomaterials obtained in Example 5 exhibits a uniform nano-dispersion morphology, good interfacial coating, a smooth macroscopic surface, and the expected elemental composition. These characteristics lay the material foundation for its application in devices such as two-mode field-effect transistors. Compared with Comparative Example 1, the material of Example 5 of this invention shows significant advantages in film quality and structural integrity, which helps to improve device performance.

[0110] Test Example 2: Electrical Performance Testing of a Dual-Mode Field-Effect Transistor

[0111] The transfer and output characteristics of the dual-mode field-effect transistor device prepared in Example 5 were tested using a Keithley 4200-SCS semiconductor parameter analyzer. Furthermore, error statistics were performed on the on / off ratio and mobility of samples with different blending ratios in Examples 1-7 to comprehensively evaluate their electrical performance. The specific test steps are as follows:

[0112] (1) Place the dual-mode field-effect transistor device on the probe stage sample stage, and turn on the sample stage vacuum pump switch and gas path switch in sequence to make the glass slide carrying the device firmly adsorbed on the sample stage surface, ensuring that the device position is not shifted and is not affected by mechanical vibration during the test.

[0113] (2) Select an objective lens with appropriate magnification and adjust the focal length until the source and drain electrodes of the field effect transistor device are clearly imaged on the display. Install test probes corresponding to the source, drain and gate electrodes respectively on the probe station probe holder, and accurately position them with the help of the display image to make each probe make reliable contact with the corresponding electrode and ensure accurate transmission of measurement signals;

[0114] (3) After completing the hardware connection, start the KTTE control software on the computer and set the parameters: transfer characteristics (I G -V G Test: Set source-drain voltage V SD Within the range of -60V to 0V, the gate voltage V G Scan from 10V to -50V; Output characteristics (I G -V SD Test: Set gate voltage V G The voltage was gradually varied from 0V to -60V, and an output characteristic curve was recorded at each gate voltage of -10V.

[0115] (4) After all measurements are completed, carefully remove the probe to avoid damaging the device structure. Through the above steps, accurate electrical characteristic data of the dual-mode field-effect transistor device can be obtained, providing experimental basis for subsequent analysis and application.

[0116] Test results are as follows Figure 9-11 As shown. Among them, Figure 9 Error distribution diagrams of on / off ratio and carrier mobility under different blending ratios are shown, indicating that when the blending ratio of PDBT-co-TT to copper / dysprosium bimetallic nanomaterial is 5:1, the novel dual-mode field-effect transistor has the optimal on / off ratio and mobility. Figure 10 The contact angle and surface energy curves of thin film devices with different blending ratios are shown. The contact angle and surface energy data confirm that all blended films exhibit hydrophobic and oleophilic properties, which can effectively block water molecules and oxygen in the environment. The film with a blending ratio of 5:1 has the lowest surface energy, indicating that its surface physical adsorption is the weakest, which is beneficial for shielding the device performance from the interference of the external environment. Figure 11 The output and transfer curves of the novel dual-mode field-effect transistor under optimal blending ratios show that the transport characteristics of hole carriers can be improved by the gate voltage V. G With effective modulation, the curve shows a good transition from the linear region to the saturation region, indicating that the device can stably regulate the current and has a reliable operating state.

[0117] Test Example 3: Stability Test of a Dual-Mode Field-Effect Transistor

[0118] The electrical performance stability of dual-mode field-effect transistors (FETs) is crucial for the development and practical application of biosensors. This test example systematically evaluates the operational stability of the dual-mode FET prepared in Example 5 by conducting continuous 48-hour electrical characteristic curve tests and 30 consecutive operating cycles.

[0119] Test results are as follows Figure 12 and Figure 13 As shown. Among them, Figure 12 The relative voltage-current variation trend of PDBT-co-TT and its blend with copper / dysprosium bimetallic nanomaterials is shown over a continuous 48-hour period. Figure 13 This shows the curves of the change in switching ratio and source-drain current during 30 consecutive repeated operations.

[0120] Figure 12-13The results show that the electrical parameters of the PDBT-co-TT hybrid device with the bimetallic nanomaterial exhibit significantly smaller variations during long-term continuous testing and multiple cycles, indicating that the novel dual-mode field-effect transistor device possesses excellent stability and maintains consistent electrical performance under long-term and repetitive testing conditions. This result not only confirms the device's good performance in short-term testing but also further demonstrates its reliability and durability during long-term use. This is of great significance for promoting the practical application of field-effect transistor-based biosensors, demonstrating the device's potential for continuous and stable operation in real-world environments and providing reliable technical support for the development and application of related sensors.

[0121] Test Example 4: Performance Testing of a Dual-Mode Biosensor

[0122] This test case provides a specific implementation method for the specific detection of the cancer biomarker TFF3 protein using a biosensor based on the dual-mode field-effect transistor prepared in Example 5, including biosensor preparation, antibody immobilization, and sensitivity, selectivity, and reliability evaluation. The preparation process of the dual-mode biosensor is described in [link to documentation]. Figure 15 The specific steps are as follows.

[0123] I. Preparation of Biosensors and Antibody Immobilization

[0124] (1) Preparation of TFF3 antibody solution: Take 1-2 mg / mL TFF3 antibody solution stored at -80℃, thaw at 4℃ and then transfer to room temperature. Perform serial dilution with 1×PBS buffer: first take 10-60 μL of the original solution, add 100-200 μL of 1×PBS, and vortex to mix; then take 10-60 μL of the mixture, add 100-200 μL of 1×PBS, and vortex to mix, finally obtaining a TFF3 antibody working solution with a concentration of 10-100 μg / mL. After preparation, store at 4℃ for later use.

[0125] (2) Sterilization of experimental environment and equipment: The workbench was sterilized by ultraviolet irradiation for 6-8 hours before the experiment; all glassware and tools used (including pipette tips, slide boxes, beakers, etc.) were autoclaved (121℃, 20 min). The sterilization process was carried out according to the standard procedure: double-distilled water was added to the autoclave until the inner liner rack was level, the items to be sterilized were placed in the autoclave and the lid was sealed, the temperature and time were set and sterilization was started, and the pressure was reduced to zero after the sterilization was completed. The items were then removed for use.

[0126] (3) Antibody immobilization at the sensor interface: Perform the following operations on a sterile operating table: Place a dust-free sponge moistened with double-distilled water in a slide box; place the silicon wafer on the sponge and add 1-5 μL of double-distilled water to fix it; take 10-30 μL of the above TFF3 antibody working solution and evenly drop it onto the copper mesh area on the silicon wafer surface; incubate at 20-25℃ for 1 hour to allow the antibody to be physically adsorbed and immobilized on the polymer surface; after incubation, gently rinse the silicon wafer surface 2-6 times with 1×PBS buffer to remove unbound antibodies; use dust-free paper to absorb residual liquid along the edge of the copper mesh, and let it stand at room temperature for 5-30 seconds to allow the surface to dry naturally. At this point, the TFF3 antibody has formed a stable biorecognition interface on the surface of the semiconductor functional layer, completing the fabrication of the copper-dysprosium bimetallic enhanced thin-film transistor biosensor.

[0127] II. Detection Principle and Signal Acquisition

[0128] After the target analyte (TFF3 protein) specifically binds to the immobilized antibody, it causes a change in the charge distribution at the device interface, thereby modulating the channel electrical properties. This is achieved by monitoring the threshold voltage Vt in the transfer curve of the dual-mode field-effect transistor device. TH With source and drain current I DS The change in TFF3 concentration enables quantitative detection. The response value is calculated using the following formula:

[0129] ;

[0130] Where V0 and I0 are the reference threshold voltage and source / leakage current before the addition of the analyte, respectively, and V and I are the corresponding values ​​measured after the reaction. Baseline stabilization is required before detection: the transfer curve is measured at least five times consecutively until the curves completely overlap, establishing a stable electrical signal baseline to ensure repeatability and accuracy of the detection.

[0131] III. Test Results and Analysis

[0132] (1) Characterization of antibody immobilization morphology: Atomic force microscopy results before and after antibody grafting onto the dual-mode biosensor are as follows: Figure 14 As shown, after antibody immobilization, the surface roughness (Rq) of the device increased from 6.05 nm to 19.8 nm, and the surface height increased from 30.328 nm to 42.765 nm, confirming that the TFF3 antibody was successfully grafted onto the semiconductor functional layer. The structure of the bi-headed broom-like copper / dysprosium bimetallic nanomaterial helps to improve antibody immobilization efficiency, providing a basis for ultra-high sensitivity detection.

[0133] (2) Sensitivity and detection limit: in different concentrations of TFF3 solution (10 0 μg / mL to 10 -9 The dual-signal response of detection threshold voltage and source-drain current was recorded in μg / mL and PBS control.TH With ΔI DS The response and result are as follows Figure 15 As shown in Table 2.

[0134] Table 2. ΔV in different concentrations of TFF3 solution and PBS control. TH With ΔI DS Response value

[0135]

[0136] from Figure 16 As shown in Table 2, this biosensor exhibits excellent sensing responses to all concentrations of TFF3, with the response values ​​showing a strong correlation with concentration. Specifically, its voltage signal detection limit is 0.132 fg / mL, and its current signal detection limit is 0.039 fg / mL, both significantly lower than the detection thresholds currently used in clinical practice. This characteristic makes it a promising candidate for early cancer screening, effectively identifying biomarkers in the early stages of disease. To ensure the reliability and accuracy of the detection results, the experiments at each concentration were repeated five times. Furthermore, a systematic analysis of the signal responses at different concentrations can further explore directions for optimizing sensor performance, thereby promoting its translational potential in practical clinical applications.

[0137] (3) Selectivity test: To verify the specific recognition ability of the prepared biosensor, selectivity tests were performed using 1×PBS buffer, TFF3, CEA, PSA, AFP and HSA at the same concentration (1 μg / mL), and the threshold voltage V was used as the threshold voltage. TH With source and drain current I DS The changes in the two signals are used as a response indicator.

[0138] Test results are as follows Figure 17 As shown, after adding 1×PBS buffer as a blank control, the device's V TH with I DS Only a slight offset occurs, resulting in ΔV TH With ΔI DS The changes were negligible, indicating that the buffer system itself did not significantly interfere with the sensor signal, verifying the rationality of the experimental design and the stability of the background signal. However, after introducing the same concentration of TFF3 protein, the device exhibited a significant ΔV... TH With ΔI DS The response confirmed the effective signal changes induced by the specific immune response. Furthermore, after adding four non-target proteins—CEA, PSA, AFP, and HSA—the ΔV corresponding to the sensor was measured. TH With ΔI DSThe changes were all significantly lower than the signal response induced by TFF3, and were at levels similar to the blank control. These results demonstrate that the biosensor possesses a high degree of specificity for the TFF3 protein, effectively distinguishing the target molecule from other structurally or functionally similar proteins, and maintaining excellent selectivity even in complex biological sample environments. This high specificity provides crucial assurance for its reliable application in clinical sample testing, contributing to improved accuracy and reliability in early cancer diagnosis.

[0139] (4) Reliability verification: The ΔV obtained from repeated operations TH With ΔI DS Data was input into four machine learning models (random forest, gradient boosting, support vector, and neural network), and the reliability of the detection results was verified by combining the four machine learning models. Specifically, the machine learning models used ΔV corresponding to samples containing known concentrations of TFF3 protein. TH and ΔI DS The dataset is obtained by pre-training as a training set.

[0140] The results are as follows Figure 18 As shown, the actual detection results of the dual-mode field-effect transistor biosensor for cancer biomarkers show minimal deviation from the predicted values ​​of the machine learning model. This result, from the perspective of data processing and model validation, further confirms the high reliability and good repeatability of the biosensor's detection results, providing effective support for the data credibility in its practical clinical applications.

[0141] In summary, this invention selects the highly mobile and stable conjugated polymer PDBT-co-TT and bi-headed broom-shaped copper / dysprosium bimetallic nanomaterials to modify the semiconductor layer. By optimizing the preparation conditions and blending ratio, a novel high-performance and stable dual-mode field-effect transistor biosensor is constructed. Simultaneously, a covalent bonding method enables efficient grafting of TFF3 antibodies without affecting the performance of organic field-effect transistor devices, thereby achieving label-free, low-cost, and rapid detection of TFF3 with ultra-high sensitivity. The detection limits for voltage signals are 0.132 fg / mL, and for current signals are 0.039 fg / mL, both significantly lower than current clinical detection values. Machine learning algorithms are used to further verify the reliability of the test results. Compared with traditional enzyme-linked immunosorbent assay (ELISA) methods, the preparation and analysis process of this sensor is lower in cost and more convenient to operate, demonstrating its practicality and convenience in clinical applications. In the future, this biosensor is expected to be closely integrated with integrated circuit technology and AI technology to achieve real-time and efficient detection of various tumor markers. This advancement will significantly improve the accuracy of early cancer diagnosis, providing a more reliable tool for clinical testing. Furthermore, the optimized biosensor design and rapid response characteristics may drive its widespread application in other biomarker detection and related fields, thus offering new solutions for early disease screening and personalized medicine.

[0142] For those skilled in the art, this invention is not limited to the details of the exemplary embodiments described above, and can be implemented in other specific forms without departing from the spirit or essential characteristics of this invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of this invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within this invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0143] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of the invention. Any minor modifications, equivalent substitutions, and improvements made to the above embodiments based on the technical essence of the present invention should be included within the protection scope of the present invention.

Claims

1. An ultra-sensitive dual-mode biosensor based on organic field effect transistors characterized in that, The application relates to a biosensor based on a dual-mode field effect transistor, and a preparation method thereof. The biosensor comprises: a dual-mode field effect transistor sequentially comprising, from bottom to top, a substrate, a gate, a dielectric layer, a semiconductor layer, and a source and a drain arranged on the semiconductor layer; and a capture antibody fixed on the surface of the semiconductor layer for specifically binding to a target biomarker. The semiconductor layer is a blended film made of a conjugated polymer PDBT-co-TT and copper / dysprosium bimetallic nanomaterials with a double-headed broom structure. The volume ratio of the conjugated polymer PDBT-co-TT to the copper / dysprosium bimetallic nanomaterials in the blended film is (1-10):(1-5).

2. The ultrasensitive dual-mode biosensor of claim 1, wherein, The conjugated polymer PDBT-co-TT is synthesized through a Stille coupling reaction, and the reaction temperature is 80-160 DEG C, and the reaction time is 48-96 h.

3. The ultrasensitive dual-mode biosensor of claim 1, wherein, The copper / dysprosium bimetallic nanomaterials are prepared by a hydrothermal method in the presence of polyvinylpyrrolidone, ascorbic acid and 1-butyl-3-methylimidazole tetrafluoroborate ionic liquid. The preparation method of the blended film is that a chlorobenzene solution of the conjugated polymer PDBT-co-TT is mixed with an ethanol solution of the copper / dysprosium bimetallic nanomaterials, and ultrasonic or stirring is performed for greater than or equal to 1 h.

4. The ultrasensitive dual-mode biosensor of claim 1, wherein, The width-length ratio of the channel region between the source and the drain is (8-20):

1.

5. The ultrasensitive dual-mode biosensor of claim 1, wherein, The target biomarker is a TFF3 protein.

6. The ultrasensitive dual-mode biosensor of claim 1, wherein, The application further discloses a preparation method of the biosensor.

7. A method of preparing the ultrasensitive dual-mode biosensor according to any one of claims 1 to 6, characterized in that, The method comprises the following steps: (1) substrate treatment: a substrate is provided, and the SiO2 dielectric layer on the surface of the substrate is modified through OTS modification, and the modification time is 3-6 h; (2) electrode preparation: a mask plate evaporation method is adopted to prepare the source and the drain which form an electrical connection with the semiconductor layer; the pattern of the mask plate enables the channel region between the source and the drain to have a width-length ratio of (8-20):1; the evaporation rate is 0.1-0.8 Å / s, and the evaporation thickness is 20-50 nm; (3) semiconductor layer preparation: a blended solution of the conjugated polymer PDBT-co-TT and the copper / dysprosium bimetallic nanomaterials is spin-coated on the channel region between the source and the drain to form the semiconductor layer; the spin-coating speed is 1500-3500 rpm, and the spin-coating time is 20-40 s; (4) annealing treatment: the prepared device is subjected to annealing treatment, the annealing temperature is 170-190 DEG C, and the annealing time is 10-20 min; (5) antibody fixation: the capture antibody is fixed on the surface of the semiconductor layer.

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