Electroactive substance detection device based on organic field effect transistor and preparation method

Abstract

The invention discloses an electroactive substance detection device based on an organic field effect transistor and a preparation method, an extended gate electrode is electrically connected with a gate electrode in a crystal sensor, and a working electrode of the extended gate electrode is modified by a specific modification film. The specific modification film is modified on the expanded gate electrode of the organic field effect transistor, so that target molecules can be specifically recognized, the influence of other molecules in a solution on a detection result is reduced, the anti-interference capability is improved, measurement errors caused by interfering substances are reduced, and the accuracy of a measurement result is improved. According to the invention, specific detection is carried out on the electroactive substance in the solution to be detected in a mode of leading out the grid electrode, the expanded grid electrode is arranged to detect the electroactive substance in the solution to be detected, and the situation that specific modification is directly carried out on the grid electrode of the organic field effect transistor, so that the performance of the organic field effect transistor becomes poor is avoided.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor manufacturing technology, and more specifically, to an electroactive material detection device based on an organic field effect transistor and a preparation method thereof. Background Art

[0002] The detection of bioactive molecules is crucial for medical health, such as neurotransmitters, uric acid, proteins, etc. Their content in the human body is one of the important indicators reflecting the health status of the human body. For example, Parkinson's disease and schizophrenia are respectively related to low and high dopamine levels; increased uric acid levels are one of the characteristics of diseases such as gout and hyperuricemia; and ascorbic acid deficiency can lead to scurvy. Therefore, early detection of these biomolecules is of great significance in physiological research, disease diagnosis and drug research.

[0003] Since these electroactive substances have redox activity, the current detection methods for these substances include electrochemical methods, chromatography, spectroscopy, and enzyme-linked immunosorbent assay (ELISA). Among them, electrochemical methods are susceptible to electrode scaling and signal interference, and have poor stability and selectivity. A lot of research has been done, including various surface modifications of electrodes, development of new materials to manufacture electrodes, new electrochemical technologies, and non-oxidative electrochemical sensors. Among these methods, the use of different molecules with inherent electrocatalytic activity to modify electrodes has shown high feasibility in distinguishing a certain electroactive substance and its related interferents.

[0004] Organic field effect transistors rely on their unique electrical properties and interactions with electroactive substances to detect electroactive substances. Under the action of diffusion in the solution, the electroactive substances gradually approach and adsorb on the surface of the organic semiconductor material of the organic field effect transistor. When the electroactive substances are adsorbed on the surface of the organic semiconductor material of the OFET, the charge distribution and carrier concentration on the surface of the material will change, thereby causing changes in the current between the source and the drain. However, other electroactive substances in the detection solution will also be adsorbed on the surface of the semiconductor material, interfering with the detection results of the target electroactive substances and reducing the accuracy of the detection results. Summary of the invention

[0005] In view of this, the present invention provides an electroactive substance detection device based on an organic field effect transistor and a preparation method, which is used to solve the problem that other electroactive substances will also be adsorbed on the surface of semiconductor materials in the existing organic field effect transistor method, interfering with the detection results of the target electroactive substances and reducing the accuracy of the detection results.

[0006] To achieve the above objectives, the proposed solution is as follows:

[0007] An electroactive substance detection device based on an organic field effect transistor comprises: an organic field effect transistor, an extended gate electrode and a control system;

[0008] The structure of the organic field effect transistor from bottom to top is a flexible substrate, a gate, a dielectric layer, an organic semiconductor layer, and a source-drain electrode layer;

[0009] The working electrode of the extended gate electrode is electrically connected to the gate of the organic field effect transistor, wherein the working electrode of the extended gate electrode is modified by a specific modification film;

[0010] The control system provides an operating voltage for the extended gate electrode, and the source and drain of the organic field effect transistor, and determines the concentration of the electroactive substance according to the source-drain current.

[0011] Preferably, the extended gate electrode comprises: three working electrodes and three reference electrodes, wherein the three reference electrodes are cascaded into one pin.

[0012] Preferably, the control system comprises: a main control chip, a DAC module, an ADC module, an OFET excitation circuit, a power module, a source power supply module, a drain power supply module, a gate power supply module, a switch, a program download module, and a Bluetooth module;

[0013] The main control chip is used to control the realization of the functions of each module in the operation of the detection device; the DAC module is used to realize the output of the circuit voltage; the ADC module receives the voltage signal transmitted by the organic field effect transistor and performs analog-to-digital conversion on it; the OFET excitation circuit is used to provide an excitation voltage for the extended gate of the organic field effect transistor; the power supply module is used to power the detection device; the source power supply module, the drain power supply module and the gate power supply module transmit electrical signals to the source, drain and gate of the organic field effect transistor respectively; the program download module is used to program and store the control program to realize the overall function of the detection device; the Bluetooth module is used for external serial port communication.

[0014] Preferably, the extended gate electrode is electrically connected to the gate in the crystal sensor, comprising:

[0015] The extended gate electrode is electrically connected to the gate of the crystal sensor through a platinum wire.

[0016] A method for preparing an organic field effect transistor, comprising:

[0017] S1. Silicon wafer treatment: rinse the silicon wafer with deionized water and alcohol, and modify the silicon wafer by ultrasonic cleaning, plasma cleaning, and OTS modification to obtain a modified silicon wafer;

[0018] S2, flexible substrate preparation: prepare SEBS1062 solution, pour it onto the modified silicon wafer, and let it stand to form a film to obtain a flexible substrate for the organic field effect transistor;

[0019] S3, preparation of dielectric layer: SEBS1052 solution is prepared by using toluene, and is spin-coated on the modified silicon wafer by a spin coater, and a dielectric layer is obtained after annealing;

[0020] S4, semiconductor layer preparation: copolymerize the organic semiconductor and SEBS1052 solution at a mass ratio of 3:7 to obtain a semiconductor material, which is then coated on a silicon wafer to obtain a semiconductor layer;

[0021] S5, electrode production: Use a mask plate to cover, and use a sprayer to spray the carbon tubes onto the silicon wafer to respectively produce the source electrode, drain electrode and gate electrode;

[0022] S6, transistor assembly: transfer and assemble the flexible substrate, gate, dielectric layer, organic semiconductor layer, source-drain electrode layer layer by layer in the order of transfer, to obtain an organic field effect transistor with a top-gate top-contact structure;

[0023] S7. Connect the extended gate electrode: Use overprinting alloy to connect the two ends of the platinum wire to the gate of the organic field effect transistor and the working electrode of the extended gate electrode respectively.

[0024] Preferably, step S3, the process of making the dielectric layer, comprises: using toluene to prepare a 60 mg / ml SEBS1052 solution, spin coating it on the modified silicon wafer by a spin coater at a speed of 1000 r / s for 60 seconds, and annealing at 100° C. for 10 minutes to obtain the dielectric layer.

[0025] Preferably, step S4, the process of making a semiconductor layer, comprises: copolymerizing 10 mg / ml of an organic semiconductor and 60 mg / ml of a SEBS1052 solution in a mass ratio of 3:7 to obtain a semiconductor material, and coating the copolymer on a silicon wafer to obtain a semiconductor layer.

[0026] It can be seen from the above technical solutions that in the electroactive substance detection device based on the organic field effect transistor provided by the present invention, the extended gate electrode is electrically connected to the gate in the crystal sensor, and the working electrode of the extended gate electrode is modified by a specific modified film. Modifying the specific modified film on the extended gate electrode of the organic field effect transistor can specifically identify the target molecule, reduce the influence of other molecules in the solution on the detection result, improve the anti-interference ability, reduce the measurement error caused by the interfering substance, and improve the accuracy of the measurement result.

[0027] The invention can improve the sensitivity of the organic field effect transistor to the target electroactive substance by modifying the surface of the extended gate electrode with a specific modified film, so that the organic field effect transistor can detect the target electroactive substance at extremely low concentration, thereby realizing the monitoring of trace substances in the organism.

[0028] The present invention realizes specific detection of electroactive substances in the solution to be tested by leading out the gate, and arranges an extended gate electrode to detect the electroactive substances in the solution to be tested, thereby avoiding direct specific modification and detection on the gate of the organic field effect transistor, which leads to poor performance of the organic field effect transistor. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0030] Figure 1 A schematic diagram of a control system structure provided in this embodiment;

[0031] Figure 2 A flow chart of a process for preparing an organic field effect transistor provided in this embodiment;

[0032] Figure 3 Characterization of the transfer characteristics of the organic field effect transistor provided in this embodiment;

[0033] Figure 4 The time stability curve of the organic field effect transistor provided in this embodiment;

[0034] Figure 5-Figure 7 They are the It curves of different substances provided in this embodiment;

[0035] Figure 8-Figure 10 They are respectively the fitting curves between the concentrations of different substances and the current provided in this embodiment;

[0036] Figure 11-13 They are respectively It curves for verifying the specific detection of different substances provided in this embodiment;

[0037] Figure 14-16 They are respectively It curves for verifying the anti-interference ability of detecting different substances provided in this embodiment. DETAILED DESCRIPTION

[0038] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0039] First, this embodiment provides an electroactive substance detection device based on an organic field effect transistor, the device comprising: an organic field effect transistor, an extended gate electrode and a control system.

[0040] The organic field effect transistor adopts a bottom gate top contact structure, and its structure from bottom to top is a flexible substrate, a gate, a dielectric layer, an organic semiconductor layer, and a source-drain electrode layer.

[0041] The organic field effect transistor and the extended gate electrode are fixed on the same substrate, and the working electrode of the extended gate electrode is electrically connected to the gate in the crystal sensor, wherein the working electrode of the extended gate electrode is modified by a specific modified film, and the working electrode of the extended gate and the gate of the organic field effect transistor can be connected by a platinum wire.

[0042] The extended gate electrode is composed of a working electrode and a reference electrode. The working electrode is made of carbon nanotubes. The surface of the working electrode is modified by a specific modification film, and the reference electrode is covered with silver. The number of the extended gate electrode working electrode and the reference electrode can be set according to the number of types of active substances to be detected. For example, if uric acid, dopamine and ascorbic acid need to be detected, the extended gate can be set with three working electrodes and three reference electrodes, and the uric acid-specific modification film, dopamine-specific modification film and ascorbic acid-specific modification film are modified on the three working electrodes respectively, wherein the three reference electrodes are cascaded into one pin.

[0043] The control system provides operating voltage for the extended gate electrode, and the source and drain of the organic field effect transistor, and determines the concentration of the electroactive substance according to the source-drain current. Figure 1As shown. The control system includes a main control chip, a DAC module, an ADC module, an OFET excitation circuit, a power module, a source power supply module, a drain power supply module, a gate power supply module, a switch, a program download module, a Bluetooth module, etc. Among them, the main control chip is used to control the realization of the functions of each module in the detection device; the DAC module is used to realize the output of 0V to -4V voltage of the circuit; the ADC module is used to receive the voltage signal transmitted from the organic field effect transistor and perform analog-to-digital conversion on it; the OFET excitation circuit is used to provide an excitation voltage to the extended gate of the organic field effect transistor; the power module is used to power the detection device; the source power supply module, the drain power supply module and the gate power supply module transmit electrical signals to the source, drain and gate of the organic field effect transistor respectively; the program download module is used to program and store the control program to realize the overall function of the detection device. The Bluetooth module contains a Bluetooth chip for external serial port communication. The control system can transmit the detection results to the outside for display through the Bluetooth module. The control system provides source-drain voltage for the organic field effect transistor and gate voltage for the extended gate, so that the source-drain current can be obtained, and the concentration of the electroactive substance can be further determined according to the It relationship curve between the source-drain current and time. The It curve is the time-current curve obtained by changing the concentration of the electroactive substance of the organic field effect transistor at different times.

[0044] In the electroactive substance detection device based on an organic field effect transistor provided by the present invention, an extended gate electrode is electrically connected to a gate in a crystal sensor, and a working electrode of the extended gate electrode is modified by a specific modification film. Modifying the specific modification film on the extended gate electrode of the organic field effect transistor can specifically identify the target molecule, reduce the influence of other molecules in the solution on the detection result, improve the anti-interference ability, reduce the measurement error caused by the interfering substance, and improve the accuracy of the measurement result.

[0045] The invention can improve the sensitivity of the organic field effect transistor to the target electroactive substance by modifying the surface of the extended gate electrode with a specific modified film, so that the organic field effect transistor can detect the target electroactive substance at extremely low concentration, thereby realizing the monitoring of trace substances in the organism.

[0046] The performance of the organic field effect transistor is prone to deterioration after being exposed to moisture. The present invention realizes specific detection of the electroactive substance in the solution to be tested by leading out the gate electrode, and arranges an extended gate electrode to detect the electroactive substance in the solution to be tested, thereby avoiding specific modification and detection directly on the gate of the organic field effect transistor, which leads to deterioration of the performance of the organic field effect transistor.

[0047] Next, this embodiment introduces the specific process of performing detection by the electroactive substance detection device provided by the above-mentioned embodiment, and the process includes:

[0048] The test solution is dripped onto the specifically modified extended gate electrode, and the test solution is ensured to cover the working electrode and the reference electrode of the extended gate electrode, and the working electrode and the reference electrode are connected. For example, if the test substances are dopamine, ascorbic acid, and uric acid, the test solutions can be urine and serum, and urine and serum both contain three electroactive substances.

[0049] A bias voltage of -1V is provided to the organic field effect transistor through the control system.

[0050] The control system obtains the source-drain current of the organic field effect transistor and determines the concentration of the electroactive substance in the solution to be tested according to the It curve obtained by fitting the organic field effect transistor.

[0051] Based on this, the process of obtaining the It curve under different concentrations of the test solution is:

[0052] The solution to be tested is dripped onto the specifically modified extended gate electrode, and it is ensured that the solution to be tested covers the working electrode and the reference electrode of the extended gate electrode, and a bias voltage of -1V is provided to the organic field effect transistor through the control system. The control system obtains the source-drain current of the organic field effect transistor. After the source-drain current changes steadily at this concentration (reaching the saturation current), the concentration of the solution to be tested is changed once. The control system records the It curve of the source-drain current of the organic field effect transistor at different concentrations over time. For example: the concentration of the solution to be tested is changed every 100s, and 150μL of the solution to be tested is dripped onto the extended gate electrode each time, and the saturation current between the source-drain electrodes of the organic field effect transistor is measured.

[0053] The present invention adopts an organic field effect transistor with modified extended gate electrode for detection, so that the energy consumption in the detection process is low, and the organic field effect transistor responds sensitively to low voltage changes, thereby improving the sensitivity of detection.

[0054] This embodiment introduces the preparation process of the organic field effect transistor in the above-mentioned electroactive material detection device. Figure 2 As shown, the process includes:

[0055] S1. Silicon wafer treatment: Rinse the silicon wafer with deionized water and alcohol, and modify the silicon wafer by ultrasonic cleaning, plasma cleaning, and OTS modification to obtain a modified silicon wafer.

[0056] S2. Preparation of flexible substrate: Prepare SEBS1062 solution, pour it onto the modified silicon wafer, and let it stand to form a film to obtain a flexible substrate for organic field effect transistors.

[0057] S3. Preparation of dielectric layer: SEBS1052 solution is prepared using toluene, and is spin-coated on the modified silicon wafer using a spin coater, and a dielectric layer is obtained after annealing.

[0058] S4, semiconductor layer preparation: copolymerize the organic semiconductor with SEBS1052 solution to obtain a semiconductor material, and apply the semiconductor material to a silicon wafer to obtain a semiconductor layer;

[0059] S5, electrode production: Use a mask plate to cover, and use a sprayer to spray the carbon tubes onto the silicon wafer to respectively produce the source electrode, drain electrode and gate electrode;

[0060] S6, transistor assembly: transfer and assemble the flexible substrate, gate, dielectric layer, organic semiconductor layer, source-drain electrode layer layer by layer in the order of transfer, to obtain an organic field effect transistor with a top-gate top-contact structure;

[0061] S7. Connect the extended gate electrode: Use overprinting alloy to connect the two ends of the platinum wire to the gate of the organic field effect transistor and the working electrode of the extended gate electrode respectively.

[0062] Next, this embodiment verifies the performance of the organic field effect transistor prepared based on the above process, and the verification process is as follows:

[0063] First, an organic field effect transistor is prepared. The flexible substrate of the organic field effect transistor prepared in this embodiment is prepared from SEBS1062, the source / drain and gate electrodes are prepared from carbon tubes, and the dielectric layer is prepared from SEBS1052. The specific preparation process is as follows:

[0064] S1. Silicon wafer treatment: rinse the silicon wafer with deionized water and alcohol; then, modify the silicon wafer by ultrasonic cleaning, plasma cleaning, and OTS modification to obtain a modified silicon wafer;

[0065] S2, flexible substrate preparation: prepare a SEBS solution with a concentration of 200 mg / ml, pour it onto the modified silicon wafer, and let it stand overnight to form a film to obtain a flexible substrate for an organic field effect transistor, wherein the SEBS is SEBS1062;

[0066] S3, preparation of dielectric layer: a SEBS solution with a concentration of 60 mg / ml is prepared by using toluene, and the solution is spin-coated on the modified silicon wafer by a spin coater at a speed of 1000 r / s for 60 seconds, and then annealed at 100° C. for 10 minutes to obtain a dielectric layer, wherein the SEBS is SEBS1052;

[0067] S4, semiconductor layer preparation: 10 mg / ml of organic semiconductor and 60 mg / ml of SEBS 1052 solution are copolymerized in a mass ratio of 3:7 to obtain a semiconductor material, which is then coated on a silicon wafer to obtain a semiconductor layer;

[0068] S5. Electrode fabrication: After using a customized mask template to block, the carbon tubes are sprayed onto the silicon wafer by a sprayer to fabricate source electrode, drain electrode and gate electrode respectively;

[0069] S6. Transistor assembly: The organic field effect transistor is assembled layer by layer in the order from bottom to top: SEBS flexible substrate, gate, dielectric layer, organic semiconductor layer, source and drain electrode layer, to obtain an organic field effect transistor device with top gate and top contact structure;

[0070] S7. Connect the extended gate electrode: Use the overprinting alloy to connect the two ends of the platinum wire to the gate of the organic field effect transistor and the working electrode of the extended gate electrode respectively, so as to complete the connection between the organic field effect transistor and the extended gate electrode.

[0071] The performance of the prepared organic field effect transistor was verified, and the verification results are as follows: Figure 3-4 The organic field effect transistor was used to perform three scans, and the scan results are shown in Figure 3 As shown. Figure 3 It can be seen that the switching ratio of the organic field effect transistor is about 10 4 The turn-on voltage is -0.1V, and the overlap of the three scans is high, which proves that the stability of the organic field effect transistor is good. The stability of the organic field effect transistor was tested for three months, and the test results are as follows Figure 4 As shown. Figure 4 It can be seen that the organic field effect transistor has good stability within three months.

[0072] This embodiment takes the detection of dopamine, uric acid and ascorbic acid as an example to introduce the process of modifying the working electrode of the extended gate electrode by a specific modification film. The extended gate electrode includes three working electrodes, and the three working electrodes are modified with specific modification films of dopamine, ascorbic acid and uric acid respectively.

[0073] The modification process is as follows:

[0074] 1. Preparation of dopamine-specific modified membrane

[0075] The working electrode of the extended gate electrode is connected to the gate of the organic field effect transistor in series through a platinum wire. Chloroauric acid is directly reduced to nanogold on the working electrode of the extended gate electrode by constant potential deposition. The solution to be tested is dripped on the electrode, and the working electrode of the extended gate electrode is connected to the reference electrode to form a conductive circuit. The cleaned electrode is placed in 18mM cysteamine at room temperature in the dark for 4 hours, then taken out, rinsed again with a large amount of anhydrous ethanol and ultrapure water, and dried with nitrogen. Take 4μl of 4-formylphenylboronic acid solution saturated with 1,4-dioxopyrimidine solution and drop it on the working electrode of the extended gate electrode, then place it in an environment of 40℃ until it is dry. The electrode is soaked in a dopamine solution at an open circuit voltage (-1V, 1 hour), and dopamine is pre-enriched on the working electrode in the form of diol, and a modified monolayer is generated on the electrode surface. Take 4μl of a 0.5% Nafion solution and drop it on the modified monolayer, irradiate it under a UV lamp until it is dry, and form a Nafion cation selective membrane.

[0076] 2. Preparation of ascorbic acid-specific modified membrane

[0077] First, 7 μl of 5 mM [Fe(CN)6]3- / 4- solution containing 0.1 M potassium chloride was dripped onto the extended gate electrode, and cyclic voltammetry was used to scan 15 times continuously in a fixed potential range, wherein the scanning potential range was E = -0.2 ~ 1 V, and the scanning rate was v = 0.05 V / S. Then, 1 mg / ml graphene oxide and 3 mg / ml sodium sulfide were mixed in a volume ratio of 1:1 to prepare a modification solution, and 7 μl of the modification solution was dripped onto the electrode and placed in a drying oven at 90 ° C for 10 min. Finally, 0.1 M PBS (pH 7) electrolyte was dripped onto the working electrode, and cyclic voltammetry was used to scan 15 times continuously in a fixed potential range for reduction to ensure the in-situ formation of graphene oxide / sodium sulfide, wherein the scanning potential range was E = -1.5 ~ 0 V, and the scanning rate was v = 0.1 V / S.

[0078] 3. Preparation of uric acid-specific modified membrane

[0079] 100 μl of 1 mM AMTa solution containing 0.1 M H2SO4 was dropped onto the extended gate working electrode, and cyclic voltammetry was used to perform 15 consecutive scans within a fixed potential range, wherein the scanning potential range was set to E=-0.2~1.7 V and the scanning rate was 50 mV / s.

[0080] This embodiment uses the electrodeposition method to modify the specific modified film on the extended gate electrode, thereby achieving specific detection of dopamine, uric acid and ascorbic acid, and reducing the measurement error caused by interfering substances in the test solution; during the detection process, the specific modified film can be reused, reducing the loss during the detection process and saving costs.

[0081] Taking the detection of dopamine, uric acid and ascorbic acid as an example, based on the organic field effect transistor and extended gate electrode provided in the above embodiment, the performance of the electroactive substance detection device is tested in this embodiment. In this embodiment, the source and drain of the probe of the lighthouse are connected to the source-drain electrode of the organic field effect transistor, and the gate of the organic field effect transistor is connected in series with the working electrode of the extended gate electrode through a platinum wire. And by dripping the solution to be tested, the working electrode and the reference electrode of the extended gate electrode are connected to form a detection closed loop. The bias voltage is given by the control system, such as: setting the bias voltage to -1V. Then, different concentrations of the solution to be tested are dripped to the working voltage, and the change of the current between the source and the drain over time is measured, and the change of the current between the source and the drain electrodes of the organic field effect transistor when the concentration of the solution to be tested changes is tested, and the It curve of the organic field effect transistor under different concentrations of the solution to be tested is obtained.

[0082] 1. Verify the detection sensitivity of each substance

[0083] 1. The content of dopamine in the human body is micromoles per liter. According to the content of dopamine in the human body, the concentration detection range can be set to 20μM~1mM. Test the test solutions containing different concentrations of dopamine and obtain the following results: Figure 5 The It curve shown is based on Figure 5 By fitting the It curve, we can get the fitting curve between dopamine concentration and current, such as Figure 8 shown.

[0084] 2. The content of ascorbic acid in the human body is micromoles per liter. According to the content of ascorbic acid in the human body, the concentration detection range can be set to 100μM~5mM. Test the test solutions containing different concentrations of ascorbic acid and obtain the following results: Figure 6 The It curve shown. Based on Figure 6 By fitting the It curve, we can get the fitting curve between ascorbic acid concentration and current, such as Fig. 9 shown.

[0085] 3. The content of uric acid in human blood is micromoles per liter, while the content of uric acid in urine is millimoles per liter. Therefore, the concentration detection range can be set to 100μM~10mM. Test the test solutions containing different concentrations of uric acid and obtain the following results: Figure 7 The It curve shown. Based on Figure 7 By fitting the It curve, we can get the fitting curve between ascorbic acid concentration and current, such as Fig.10 shown.

[0086] According to the above test results, the electroactive substance detection device provided in this embodiment can accurately detect uric acid, dopamine and ascorbic acid in the human body.

[0087] 2. Verify the specificity of each substance detection

[0088] 1. On the dopamine-specific modified working electrode, 150 μl and 500 μM ascorbic acid, uric acid and dopamine were added before and after, respectively. In addition, 150 μl of PBS buffer was added to the working electrode as a blank control. The source-drain current after adding each solution was measured. The It curve of the test is as follows: Fig.11 As shown. Fig.11 It can be seen that the change in current caused by dopamine is the largest.

[0089] 2. On the working electrode modified with ascorbic acid, 150 μl of uric acid, 1 mM of dopamine and ascorbic acid were added before and after, respectively. In addition, 150 μl of water was added to the working electrode as a blank control. The source-drain current after adding each solution was measured. The It curve of the test is as follows: Fig.12 As shown. Fig.12 It can be seen that ascorbic acid causes the largest change in current.

[0090] 3. On the working electrode modified specifically with uric acid, 150 μl and 100 μM dopamine, ascorbic acid and uric acid were added before and after, respectively. In addition, 150 μl of PBS was added to the working electrode as a blank control. The source-drain current after adding each solution was measured. The It curve of the test is as follows: Fig.13 As shown. Fig.13 It can be seen that uric acid causes the largest change in current.

[0091] According to the above test results, it can be seen that the electroactive substance detection device provided in this embodiment can specifically detect uric acid, dopamine and ascorbic acid in the human body.

[0092] 2. Verify the anti-interference ability of the detection device for the detection of various substances

[0093] 1. On the dopamine-specific modified working electrode, a dopamine solution and a mixed solution of dopamine and other interfering substances were added dropwise, wherein the concentration of dopamine in each test solution was the same. In addition, PBS buffer was added dropwise to the working electrode as a blank control. The source-drain current after adding each solution was measured, and the It curve of the test was as follows: Fig.14 As shown. Fig.14 It can be seen that the overlap of the saturation current between the source and drain electrodes of the dopamine solution and the mixed solution is relatively high, and the interference substances have little effect on the detection results of the dopamine concentration.

[0094] 2. Add ascorbic acid solution and mixed solution of ascorbic acid and other interfering substances to the working electrode modified with ascorbic acid, respectively. The concentration of ascorbic acid in each test solution is the same. In addition, add water to the working electrode as a blank control. Measure the source-drain current after adding each solution. The It curve of the test is as follows: Fig.15 As shown. Fig.15 It can be seen that the overlap of the saturation current between the source and drain electrodes of the ascorbic acid solution and the mixed solution is relatively high, and the interference substances have little effect on the detection result of the ascorbic acid concentration.

[0095] 3. Uric acid solution and mixed solution of uric acid and other interfering substances were added to the working electrode specifically modified with uric acid and the working electrode specifically modified with dopamine, respectively, wherein the concentration of uric acid in each test solution was the same. In addition, PBS buffer was added to the working electrode as a blank control. The source-drain current after adding each solution was measured, and the It curve of the test was as follows: Fig.16 As shown. Fig.16 It can be seen that the overlap of the saturation current between the source and drain electrodes of the uric acid solution and the mixed solution is relatively high, and the interference substances have little effect on the detection results of uric acid concentration.

[0096] According to the above test results, the electroactive substance detection device provided in this embodiment has a strong anti-interference ability when detecting the concentration of the target electroactive substance in the human body.

[0097] Finally, it should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprises" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device that includes a series of elements includes not only those elements. The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same and similar parts between the various embodiments can be referenced to each other.

[0098] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An electroactive substance detection device based on an organic field effect transistor, characterized in that: include: Organic field effect transistors, extended gate electrodes and control systems; The structure of the organic field effect transistor from bottom to top is a flexible substrate, a gate, a dielectric layer, an organic semiconductor layer, and a source-drain electrode layer; The working electrode of the extended gate electrode is electrically connected to the gate of the organic field effect transistor, wherein the working electrode of the extended gate electrode is modified by a specific modification film; The control system provides an operating voltage for the extended gate electrode, and the source and drain of the organic field effect transistor, and determines the concentration of the electroactive substance according to the source-drain current.

2. The electroactive substance detection device based on organic field effect transistor according to claim 1, characterized in that: The extended gate electrode includes three working electrodes and three reference electrodes, wherein the three reference electrodes are cascaded into one pin.

3. The electroactive substance detection device based on organic field effect transistor according to claim 1, characterized in that: Control system, including: main control chip, DAC module, ADC module, OFET excitation circuit, power module, source power supply module, drain power supply module, gate power supply module, switch, program download module, Bluetooth module; The main control chip is used to control the realization of the functions of each module in the operation of the detection device; the DAC module is used to realize the output of the circuit voltage; the ADC module receives the voltage signal transmitted by the organic field effect transistor and performs analog-to-digital conversion on it; the OFET excitation circuit is used to provide an excitation voltage for the extended gate of the organic field effect transistor; the power supply module is used to power the detection device; the source power supply module, the drain power supply module and the gate power supply module transmit electrical signals to the source, drain and gate of the organic field effect transistor respectively; the program download module is used to program and store the control program to realize the overall function of the detection device; the Bluetooth module is used for external serial port communication.

4. The electroactive substance detection device based on organic field effect transistor according to claim 1, characterized in that: The extended gate electrode is electrically connected to a gate in the crystal sensor, and includes: The extended gate electrode is electrically connected to the gate of the crystal sensor through a platinum wire.

5. A method for preparing an organic field effect transistor, characterized in that: The method for preparing the organic field effect transistor according to any one of claims 1 to 4 comprises: S1. Silicon wafer treatment: rinse the silicon wafer with deionized water and alcohol, and modify the silicon wafer by ultrasonic cleaning, plasma cleaning, and OTS modification to obtain a modified silicon wafer; S2, flexible substrate preparation: prepare SEBS1062 solution, pour it onto the modified silicon wafer, and let it stand to form a film to obtain a flexible substrate for the organic field effect transistor; S3, preparation of dielectric layer: SEBS1052 solution is prepared by using toluene, and is spin-coated on the modified silicon wafer by a spin coater, and a dielectric layer is obtained after annealing; S4, semiconductor layer preparation: copolymerize the organic semiconductor and SEBS1052 solution at a mass ratio of 3:7 to obtain a semiconductor material, which is then coated on a silicon wafer to obtain a semiconductor layer; S5, electrode production: Use a mask plate to cover, and use a sprayer to spray the carbon tubes onto the silicon wafer to respectively produce the source electrode, drain electrode and gate electrode; S6, transistor assembly: transfer and assemble the flexible substrate, gate, dielectric layer, organic semiconductor layer, source-drain electrode layer layer by layer in the order of transfer, to obtain an organic field effect transistor with a top-gate top-contact structure; S7. Connect the extended gate electrode: Use overprinting alloy to connect the two ends of the platinum wire to the gate of the organic field effect transistor and the working electrode of the extended gate electrode respectively.

6. The method for preparing an organic field effect transistor according to claim 5, characterized in that: Step S3, the process of making the dielectric layer, includes: using toluene to prepare a 60 mg / ml SEBS1052 solution, spin coating it on the modified silicon wafer by a spin coater at a speed of 1000 r / s for 60 seconds, and annealing at 100° C. for 10 minutes to obtain the dielectric layer.

7. The method for preparing an organic field effect transistor according to claim 5 or 6, characterized in that: Step S4, the process of making the semiconductor layer, includes: copolymerizing 10 mg / ml of an organic semiconductor and 60 mg / ml of a SEBS1052 solution at a mass ratio of 3:7 to obtain a semiconductor material, and coating the semiconductor material on a silicon wafer to obtain a semiconductor layer.

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