High-performance organic electrochemical transistor array sensitive element and sensor

Abstract

The invention belongs to the field of sensors, and relates to a high-performance organic electrochemical transistor array sensitive element and a sensor, and the sensitive element is composed of an array composed of a plurality of high-performance organic electrochemical transistors; the high-performance organic chemical transistor comprises a substrate, a source electrode, a drain electrode, a grid electrode, a gold electrode, a dielectric liquid ball, a P-type organic dielectric layer and an N-type organic dielectric layer, through holes are formed in the corresponding positions of the grid electrode and the substrate, and conductive materials are injected into the through holes; the dielectric liquid ball is arranged on the central point of the P-type organic dielectric layer and covers a part of the grid electrode; the dielectric liquid ball is a sensitive material for realizing biological detection; according to the invention, the OECT array is combined with a specifically designed signal acquisition circuit, so that the signal detection precision and the transmission rate are improved.

Description

Technical Field

[0001] The present invention belongs to the field of sensors, and particularly relates to a high-performance organic electrochemical transistor array sensitive element and a sensor. Background Art

[0002] As an emerging sensing technology, the organic electrochemical transistor (OECT) has been widely used in the fields of biosensing, wearable electronics, and intelligent sensors due to its ultra-high sensitivity, low driving voltage, and excellent biocompatibility. The working mechanism of OECT is based on the characteristics of mixed ion-electron conductors, which gives it unique advantages in detecting bioelectrochemical signals. However, traditional OECTs have various limitations. The structure of the conventional planar OECT occupies a large space and has a low integration density, which is not conducive to large-scale array detection. The detection effect is not good during long-term use, affecting its practical application effect. The electro-chemical reaction and switching speed are relatively slow, which also limits its application in high-frequency detection.

[0003] Due to the limitation of the planar structure, the integration density of OECT is relatively low, making it difficult to meet the requirements of high-density integrated circuits (low integration density). The performance of N-type OECTs is far inferior to that of P-type devices, resulting in limited overall circuit performance (poor performance of N-type devices). Currently, to solve the problems faced by the traditional OECT structure, the sensing research on organic electrochemical transistors mainly includes double-gate organic electrochemical transistors represented by the publication number CN 113607795B, organic electrochemical transistor sensors based on molecularly imprinted membranes represented by the publication number CN 106770515B, and an organic electrochemical transistor sensor based on a molecularly imprinted membrane represented by the publication number CN 106770515B. The above-mentioned proposed organic electrochemical sensors still have problems such as limited performance, low integration density, and poor detection effect. To solve the above problems, the publication number CN 114384134B proposed a method for constructing an organic optoelectrochemical transistor sensor based on a zinc oxide nanorod array. This invention uses the prepared ZnO NRs as the optoelectroactive material to create a highly sensitive OECT sensing platform. However, it still has not explored the detection effect of multi-unit OECT sensing. The publication number CN 112864324B uses PEDOT / PSS thin films as both the gate and source-drain layers. The prepared organic electrochemical transistors exhibit high transconductance and high on-off ratio, which helps to amplify signals and improve the sensitivity of detection. However, it has problems such as unstable and non-reproducible test results.

[0004] The above integrated OECT array only conducts the research on the body of OECT devices for the needs in the field of integrated circuits. Due to the high transconductance, high current density, etc. of OECT, it also has great application prospects in the field of sensing and detection. To meet the various biosensing requirements for the screening of chronic diseases such as diabetes, hypertension, Alzheimer's disease, the detection of viruses such as novel coronavirus and influenza A virus, the detection of bacteria such as Staphylococcus aureus and Escherichia coli, as well as the detection of mycoplasma and human hormones, two parts of work still need to be integrated on the above integrated OECT array: 1. Integrate the antibody-sensitive materials corresponding to biomarkers; 2. Integrate a signal processing chip to achieve multi-channel high-precision signal acquisition, processing, etc. However, there has been no relevant reported progress in the integration of OECT components. The research on the detection effect of integrated array-type OECT is still a field to be explored. Summary of the Invention

[0005] To solve the problems existing in the above prior art, the present invention proposes a high-performance organic electrochemical transistor array sensitive element. The device includes: the sensitive element is composed of an array of multiple high-performance organic chemical transistors coated with sensitive materials; a single high-performance organic chemical transistor coated with sensitive materials includes: a substrate, a source electrode, a drain electrode, a gate electrode, a gold electrode, a dielectric liquid sphere, a P-type organic dielectric layer, and an N-type organic dielectric layer; the source electrode, the drain electrode, the gate electrode, and the gold electrode are all arranged on the upper surface of the substrate, and the P-type organic dielectric layer covers the source electrode, the P-type organic dielectric layer is connected to the drain electrode, the drain electrode is connected to the N-type organic dielectric layer, the gold electrode is connected to the source electrode, a part of the N-type organic dielectric layer covers the P-type organic dielectric layer, and a part covers the drain electrode; through holes are arranged at corresponding positions of the gate electrode and the substrate, and conductive materials are injected into the through holes so that the bottom of the gate electrode is conducted with the base electrode; the dielectric liquid sphere is arranged at the center point of the organic dielectric layer and covers a part of the gate electrode.

[0006] A sensor using the high-performance organic chemical transistor array sensitive element includes: a sensitive element, an ASIC circuit chip, a packaging substrate, a potting material, and leads; wherein the sensitive element uses the high-performance organic electrochemical transistor array sensitive element described in claim 1; the ASIC circuit chip is arranged on the upper surface of the packaging substrate; the high-performance organic electrochemical transistor array sensitive element is arranged on the upper surface of the ASIC circuit chip and is electrically connected through leads; the potting material is injected into the packaging substrate so that a protective barrier is formed in the gap around the high-performance organic electrochemical transistor array sensitive element to form a sensor.

[0007] Advantages of the present invention:

[0008] By integrating high-performance organic chemical transistors, the present invention solves the problems of small scale of existing OECT arrays, low recognition efficiency, narrow detection range, and difficulty in achieving required performance caused by weak detection effect of unit OECT components. On the basis of existing high-performance organic electrochemistry, the present invention further optimizes the performance of unit OECTs, improving the detection threshold and the number of detections. The present invention combines the OECT array with a signal acquisition circuit with a specific design for the first time, improving the signal transmission rate and achieving the effect of rapid detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 Schematic diagram of the OECT component of the present invention;

[0010] Figure 2 Top view of the OECT component of the present invention;

[0011] Figure 3 Test diagram of the OECT component of the present invention;

[0012] Figure 4 Schematic diagram of the dielectric of the OECT component of the present invention;

[0013] Figure 5 Schematic diagram of the basic module of the SAR ADC circuit of the present invention;

[0014] Figure 6 ASIC circuit structure diagram of the present invention;

[0015] Figure 7 Structural diagram of the arrayed OECT sensitive component of the present invention;

[0016] Figure 8 Three-dimensional heterogeneous integration structure diagram of the OECT biosensor of the present invention;

[0017] Figure 9 High-reliability integrated packaging structure diagram of the OECT biosensor of the present invention;

[0018] Figure 10 Structural schematic diagram of the OECT biosensor of the present invention after high-reliability integrated packaging;

[0019] Figure 11 Fabrication method of the sensor using the high-performance organic chemical transistor array sensitive component of the present invention;

[0020] Among them, 1. Source electrode, 2. Drain electrode, 3. Gate electrode, 4. Gold electrode, 5. Substrate, 6. Dielectric liquid sphere, 7. Pad, 8. Copper filling, 9. Organic dielectric layer, 10. Solder ball, 11. P-type organic dielectric layer, 12. N-type organic dielectric layer, 13. OECT array, 14. ASIC circuit chip, 15. Sensor substrate, 16. Gold wire. Specific embodiments

[0021] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0022] A high-performance organic electrochemical transistor array sensitive element, as Figures 1 to 4 shown. The device includes: The sensitive element consists of an array composed of multiple high-performance organic chemical transistors coated with sensitive materials; A single high-performance organic chemical transistor coated with sensitive materials includes: a substrate, a source electrode, a drain electrode, a gate electrode, a gold electrode, a dielectric liquid sphere, a P-type organic dielectric layer, and an N-type organic dielectric layer; The source electrode, drain electrode, gate electrode, and gold electrode are all arranged on the upper surface of the substrate, and the P-type organic dielectric layer covers the source electrode, the P-type organic dielectric layer is connected to the drain electrode, the drain electrode is connected to the N-type organic dielectric layer, the gold electrode is connected to the source electrode, and a part of the N-type organic dielectric layer covers the P-type organic dielectric layer and a part covers the drain electrode; Through holes are provided at corresponding positions of the gate electrode and the substrate, and conductive materials are injected into the through holes to make the bottom of the gate electrode conduct with the base electrode; The dielectric liquid sphere is arranged at the center point of the organic dielectric layer and covers a part of the gate electrode.

[0023] The present invention proposes a high-performance OECT array integrated detection element. This element consists of three parts, including sensitive materials, an OECT array, and an ASIC circuit. The OECT sensitive detection array and the circuit substrate are stacked and assembled by bonding, adhering, etc.

[0024] The working principle of the OECT sensor is as follows: When a voltage is applied between the gate and the source of the detection unit, ions in the electrolyte will migrate into the semiconductor material. The injection of ions will cause an increase in the concentration of free carriers in the semiconductor material, thereby increasing the conductivity of the material and entering the working preparation state. After the target analyte reaches the gate, it reacts with the modification material or antigen-antibody on the gate to form zwitterionic cations and anions. Due to the increase in the carrier concentration during the reaction, the conductivity of the semiconductor material also increases. This change in conductivity affects the current flowing through the channel, thereby achieving the control of the current. By adjusting the gate voltage, the source-drain current can be controlled to achieve signal amplification and modulation. The OECT sensor can amplify the electrochemical reaction signal occurring on the gate through the channel current. The generated current is proportional to the concentration of the target substance. By measuring the current, the concentration of the target substance can be determined. The generated electrical signal is converted into a readable signal through operations such as amplification, filtering, and analog-to-digital conversion for analysis and detection. This enables the OECT to have the advantages of high sensitivity and low detection limit when detecting tiny biological and chemical signals.

[0025] In this embodiment, the material part includes the channel material and the sensitive material, where the sensitive material is the gate modification material. Next, it will be analyzed from three perspectives: the function, classification, and integration of the materials.

[0026] The channel materials include: The channel materials of OECT have high conductivity and good biocompatibility. It can effectively transport electrons and ions, enabling the OECT to convert chemical signals into electrical signals, thereby achieving signal amplification and transmission. Commonly used channel materials include, but are not limited to, PEDOT:PSS, n-type OECT polymer materials, small molecule semiconductor materials, zwitterionic functionalized materials, etc.

[0027] The integration of the channel materials usually includes the following steps: First, an appropriate substrate needs to be prepared, such as a silicon wafer, glass, or flexible plastic, etc. This substrate should have a flat surface and good conductivity to facilitate the subsequent steps. Next, the π-conjugated polymer is deposited on the substrate through appropriate deposition techniques (such as spin coating, drop coating, sputtering, or printing, etc.) to form the channel layer. This channel layer will serve as the core part of the OECT, responsible for conducting electrons and ions. At both ends of the channel layer, the source and drain electrodes need to be prepared. These electrodes are usually made through metal deposition or printing techniques and have good conductivity to provide current when the transistor is working.

[0028] In this embodiment, the gate modification material can endow the OECT with the ability to specifically detect specific substances, broaden the detection range, significantly improve the detection sensitivity to specific substances, enhance biocompatibility, and play a key role in improving device performance and application scope. Commonly used gate modification materials include, but are not limited to, carbon nanotubes (CNT), graphene, polyelectrolytes, polyaniline, polypyrrole, biomolecules such as enzymes, antibodies, etc. and their composites.

[0029] The gate is usually located on one side of the channel layer and is separated from the channel layer by a layer of gate insulating layer. The preparation of the gate also requires good electrical conductivity and can be made by appropriate deposition or printing techniques. The surface of the gate or channel layer of the OECT needs to be modified to bind to the antibody. This usually involves using self-assembled monolayers (SAMs) or other surface chemistry techniques to provide appropriate binding sites. Next, the target antibody is immobilized on the surface of the gate or channel layer. This can be achieved by methods such as physical adsorption, chemical cross-linking, or biospecific binding. During the immobilization process, it is necessary to ensure that the activity and specificity of the antibody are not affected. To prevent non-specific binding and interference, the surface immobilized with the antibody usually needs to be blocked. This can be achieved using appropriate blocking agents (such as proteins, polysaccharides, etc.) to cover the sites that have not bound to the antibody.

[0030] In this embodiment, the design and micro-nano fabrication of the arrayed vertical OECT sensing element include: The vertical organic electrochemical transistor (OECT) with a vertical structure is an innovative design aimed at overcoming the limitations of traditional planar-structured OECTs. The first step in fabricating the OECT structure is to select a suitable silicon-based substrate, and then deposit the bottom electrode of the gold source electrode. Next, a layer of polymer material is deposited on the gold electrode. This layer is used to isolate the bottom electrode and the upper structure to prevent short circuits. Then, the electrode of the gold drain is deposited using the same operation, and a second layer of polymer material is deposited on the drain. Finally, the gold gate is deposited on the top layer, and the organic semiconductor material is deposited on the insulating layer. This layer of material will serve as the channel of the OECT. The channel material is cured using ultraviolet light to enhance its mechanical stability and electrical properties. This step can significantly improve the stability and performance of the device. The end of the gate is drilled and filled with copper to the left gold electrode, and the bottom of the substrate is spot-welded to conduct electricity.

[0031] Compared with traditional single OECT electrodes, microarrayed OECT devices have higher current density, faster mass transfer rate, and better signal-to-noise ratio, enabling highly sensitive and multi-parameter detection of trace biomarkers. After achieving high-density arraying of OECTs, detection can be carried out simultaneously at multiple sites, thus significantly enhancing the ability to capture and amplify weak signals of biomarkers. To meet the requirements of the sensor for high sensitivity, high accuracy, and rapid detection of biological signals, this study focuses on the design and mass production of microarrayed OECT sensing elements. By optimizing the OECT array structure, the integration, accuracy, and reliability of the sensing elements are further improved. At the same time, micro-nano processing and fabrication technologies suitable for this type of OECT array are studied, practical process flows are formulated, process parameters such as photolithography, etching, evaporation, and sputtering for the patterning of OECT electrodes are optimized, and research on the processing stability and repeatability control technology of OECT arrays is carried out to fabricate OECT sensing elements with high consistency and high reliability.

[0032] In this embodiment, as Figure 6 shown, the low-power and high-signal-to-noise-ratio ASIC circuit includes: This ASIC circuit needs to have the characteristics of low power consumption and high sensitivity to ensure the accurate acquisition and processing of signals. To solve the two key technical problems of signal-to-noise ratio and power consumption optimization, this design solution starts from multiple dimensions, including circuit structure design, analog and digital mixed-signal processing. The main functions of the ASIC chip are low-noise analog signal amplification, signal extraction, analog-to-digital conversion for a single signal, and logical timing control of multi-channel signals after arraying. In the design of the ASIC circuit structure, considering the current-voltage characteristics of the OECT sensor, a highly adaptable circuit structure is developed. Its core goal is to achieve low-power operation to extend the service life of the sensor system and reduce energy consumption, while ensuring high-sensitivity signal detection ability to accurately capture and amplify the weak signals output by the OECT sensor. Utilizing the low-power characteristics of CMOS technology, the intensity of the sensor output signal is further enhanced and external noise interference is reduced, and a high-performance low-noise, high-gain operational amplifier circuit is designed. The amplifier adopts a multi-stage amplification structure, and its circuit layout and component parameters are carefully designed to ensure the stability between stages of amplification, thereby enhancing the signal gain. By using precisely matched resistor and capacitor values for noise suppression and combining negative feedback technology to improve gain stability, it is ensured that the amplified signal remains within the working range.

[0033] In the aspect of analog and digital mixed-signal processing, a mixed-signal processing ASIC circuit combining a high-performance analog front end (AFE) and a low-power analog-to-digital converter (ADC) is designed. The AFE is responsible for preprocessing operations such as amplifying and filtering the weak analog signals output by the OECT sensor, thereby improving the signal-to-noise ratio and dynamic range of the signals. The ADC then converts the processed analog signals into digital signals for further analysis and processing by the subsequent digital signal processing unit. In addition, signal preprocessing algorithms are studied, and the circuit structure of the AFE is optimized in combination with the characteristics of the OECT sensor.

[0034] In this embodiment, as Figure 5 shown, the ADC structure adopts the successive approximation register (SAR) as the core architecture. By studying ways such as comparator design and clock control to improve efficiency, the conversion accuracy and speed of the ADC can be effectively improved. The AFE receives the weak current signal transmitted from the source-drain of the OECT for preprocessing operations such as amplification and filtering, thereby improving the signal-to-noise ratio and dynamic range of the signal. In the ADC, V REF作为 reference voltage , V IN is the input voltage. First, the analog signal is discretized in time through S / H, that is, sampled. After sampling, the signal is held at a fixed value V SH . In the SAR, in a successive approximation manner, starting from the highest bit, the quantization value is gradually reduced. B 0 to B n-1 is the step-by-step comparison of the voltages from the high bit to the low bit on the comparator. CLK controls the operation timing of the comparator. It is converted into an analog value through the DAC. COMP is used as the comparator to compare the analog value with the input signal, and the quantization value is adjusted according to the comparison result until the quantization value closest to the input signal is found. The quantization value is compared with the input signal, and finally the digital signal to be output is obtained. The gate receives an external voltage to achieve a controllable voltage and can output a signal through voltage comparison. The sensor power supply receives an external current to operate.

[0035] The logical timing control of multi-channel signals is a key link to ensure the correct function and performance optimization of the chip. The high-performance OECT array integrated detection element consists of multiple OECT units. When each OECT works in the dissipative state, the current when a large number of OECTs in the integrated array work simultaneously is relatively large, which is not conducive to the safe and normal operation of the chip. Therefore, the addressing method is used to make only a single device work at a certain moment, and through the polling method, the signals of each OECT are read in turn, thereby realizing the signal reading of the array. Through the above strategy, the logical timing of multi-channel signals in the ASIC chip can be effectively controlled to ensure the correct function and performance optimization of the chip.

[0036] In terms of power optimization and power management, the present invention designs an intelligent power scheduling system, which dynamically adjusts the voltage and current distribution of the power supply according to different requirements, so as to meet various performance requirements while minimizing energy consumption.

[0037] In this embodiment, the sensitive components are three-dimensionally hetero-integrated, that is, the three-dimensional hetero-integration technology based on through-silicon vias (TSV) is adopted to optimize the array topology and microfabrication to ensure efficient electrical connection between the OECT and the ASIC circuit.

[0038] After the three-dimensional hetero-integration is completed, the OECT array is integrally packaged to ensure its reliability in various environments. Select a suitable chip adhesive, design the curing process, and optimize the electrical signal lead-out method to realize the micro-assembly of the ASIC circuit, the OECT sensitive component and the substrate. Encapsulation is carried out by using technologies such as epoxy molding compound to protect the ASIC circuit and the OECT sensitive component from the external environment, and at the same time ensure that the contact area between the OECT and the sample to be measured is exposed to achieve highly reliable integral packaging.

[0039] A sensor using a sensitive component of a high-performance organic chemical transistor array, such as Figures 7 to 10 shown, the device includes: a sensitive component, an ASIC circuit chip, a packaging substrate, potting material and leads; wherein the sensitive component is the high-performance organic electrochemical transistor array sensitive component described in claim 1; the ASIC circuit chip is arranged on the upper surface of the packaging substrate; the high-performance organic electrochemical transistor array sensitive component is arranged on the upper surface of the ASIC circuit chip and is electrically connected through leads; the potting material is injected into the packaging substrate so that a protective barrier is formed in the gap around the high-performance organic electrochemical transistor array sensitive component to form a sensor.

[0040] A high-performance organic electrochemical transistor (OECT) array integrated detection component aims to improve the sensitivity, accuracy and reliability of biosensors. The OECT sensitive component and the ASIC circuit part of this component are laminated and assembled into one body by means of bonding, sticking, etc. to ensure the superiority of the overall performance. The following introduces the key step embodiments of the OECT sensor, including the vertical OECT preparation process, OECT gate modification, ASIC circuit, three-dimensional integration process and sensor packaging process, as Figure 11 shown, including:

[0041] (1) Preparation process of vertical OECT

[0042] First, perform TSV via processing on the selected silicon substrate. TSV (Through Silicon Via) via, that is, silicon through-hole, is a vertical interconnection technology that penetrates the silicon wafer or chip. The process of fabricating TSV vias involves multiple precise technological steps. First, form a layer of silicon dioxide (SiO 2 ) layer on the silicon substrate, which can be achieved by thermal oxidation or plasma-enhanced chemical vapor deposition (PECVD) methods. Coat a photoresist on the silicon dioxide layer. Through the exposure and development steps, pattern the photoresist to define the area for subsequent silicon etching. Use dry etching (such as deep reactive ion etching DRIE) or wet etching to etch vias in the silicon substrate. After etching, remove the photoresist to prepare for the next technological steps. Deposit a layer of silicon dioxide on the hole walls as an insulating layer by PVD, PECVD, or atomic layer deposition (ALD) technology to prevent the deposition of a conductive barrier layer, such as titanium / copper (Ti / Cu) or tantalum / copper (Ta / Cu), on the insulating layer, so that the subsequent copper plating can adhere better and prevent electron migration. Perform copper plating on the insulating layer and the barrier layer to fill the TSV holes. This is usually done by electroplating. After electroplating, perform an annealing process to release stress. Perform a CMP step to planarize the surface, remove the excess copper and the barrier layer, leaving a copper TSV flush with the surface of the silicon substrate. Thin the wafer as required. Make bumps on the front or back of the wafer for subsequent packaging and interconnection. Stack the fabricated TSV wafer with other wafers or chips and achieve interconnection through bonding technology. Test the fabricated TSV vias to ensure their electrical performance and reliability.

[0043] Select a suitable substrate material and perform cleaning and drying treatments to ensure its surface is clean and free of impurities. Prepare the source electrode on the substrate, and form a dense and well-conductive gold electrode by methods such as metal evaporation or sputtering. Prepare a porous semiconductor layer on the source electrode, which is composed of an electrochemically active polymer semiconductor material. The porous structure helps with ion transport and storage, thus improving the performance of the transistor. Prepare the drain electrode on the porous semiconductor layer, and also form a gold electrode by methods such as metal evaporation or sputtering. The drain electrode is connected to the source electrode through the porous semiconductor layer to form the channel of the transistor. Prepare a packaging layer on the substrate to protect the transistor from the external environment. The packaging layer needs to expose the part where the drain electrode overlaps with the source electrode for the subsequent preparation of the electrolyte layer. Prepare the electrolyte layer above the drain electrode, which provides a medium for ion transport for the transistor. The selection and preparation of the electrolyte layer have an important impact on the performance of the transistor. Finally, prepare the gate electrode connected to the electrolyte layer. The gate electrode affects the channel conductivity of the transistor by regulating the ion concentration in the electrolyte layer.

[0044] (2) ASIC circuit

[0045] The ASIC circuit using standard CMOS integrated circuit technology combines the advantages of low power consumption, high speed, and strong anti-interference ability of the CMOS process, and has become the mainstream choice for current large-scale integrated circuits. The ASIC circuit designed in this part is specifically tailored for the OECT sensor, with the characteristics of low power consumption and high sensitivity to optimize the acquisition and processing of signals. In terms of circuit structure design, based on the current-voltage characteristics of the OECT sensor, a circuit structure highly matched with it is designed to ensure low-power operation and high-sensitivity signal detection. A multi-stage amplification structure is adopted to design an operational amplifier with high gain and low noise. Noise suppression is carried out through precisely matched resistor and capacitor values, and negative feedback technology is used to improve the gain stability. For mixed-signal processing, a high-performance analog front end (AFE) and a low-power analog-to-digital converter (ADC) are designed to ensure that the weak analog signal output by the OECT sensor can be accurately converted into a digital signal after amplification and filtering for subsequent analysis.

[0046] (3) Three-dimensional integration process

[0047] The three-dimensional integration process of OECT (organic electrochemical transistor) is a complex and delicate process, and welding is a crucial step among them. Welding plays a key role in connecting various components in the three-dimensional integration of OECT. During the preparation process of OECT, since it is necessary to avoid direct contact between the electrolyte and the source and drain electrodes to reduce parasitic capacitance, the welding process requires special care and precision.

[0048] (4) OECT gate modification

[0049] Since the target antibody is positively charged in neutral and acidic electrolytes, it can be fixed on the gate surface. In this way, an electric dipole will be formed on the gate surface, changing the surface potential of the gold gate electrode, thereby changing the effective gate voltage of the transistor. By testing the offset of the transfer curve of the transistor before and after the antibody reaction, the concentration or quantity of the antibody can be judged.

[0050] The gate surface is cleaned and processed to ensure that the antibody can firmly adhere to the gate. Methods such as chemical bonding, physical adsorption, or self-assembled monolayers are used to fix the antibody on the gate surface. During the fixation process, it is necessary to ensure that the activity of the antibody is not affected so that it can specifically bind to the target biomolecule subsequently. The fixed antibody is characterized and tested to ensure its stability and activity. The concentration and fixation conditions of the antibody are adjusted as needed to optimize the performance of the sensor.

[0051] For example, for the detection of influenza A (such as the H1N1 influenza virus), specific antibodies against the influenza A virus can be selected for integration. First, specific antibodies against the influenza A virus are isolated and purified from biological samples (such as the serum of convalescent patients). A self-assembled monolayer (SAM) is formed on the gate of the OECT (usually a gold electrode), for example, using mercaptoacetic acid (MUA) or mercaptopropionic acid (MPA). Then, the antibody is covalently bonded to the SAM through a chemical crosslinking agent (such as EDC / NHS). This method ensures that the antibody is stable and functional on the gate surface.

[0052] (5) Sensor encapsulation process

[0053] The packaging process of OECT (organic electrochemical transistor) sensors is a complex and delicate process, aiming to protect the internal components of the sensors, improve stability and reliability. Wire bonding is a key step in connecting OECTs with other electronic components (such as circuit boards, electrodes, etc.). In the 3D integration of OECTs, wire bonding needs to meet the requirements of high reliability, high conductivity and low cost. At the same time, the wire materials also need to have high conductivity, good mechanical strength and corrosion resistance. Commonly used wire materials include gold wires, silver wires, aluminum wires, etc. Among them, gold wires are widely used due to their excellent conductivity and corrosion resistance. Ultrasonic bonding is selected to use the energy generated by ultrasonic vibration to press the wire into the pad and form a firm connection. This method is suitable for bonding of fine wires and causes less damage to the organic materials inside the OECT. The bonding quality directly affects the performance and reliability of the OECT. It is necessary to strictly test the strength, conductivity and sealing performance of the bonding points. Methods such as electrical testing and microscopic observation can be used to detect the bonding quality. First, align the pins of the OECT sensor with the pads on the substrate, and then use welding equipment to weld the pins to the pads. During the welding process, it is necessary to control the welding temperature and time to avoid damaging the organic materials inside the OECT sensor. One end of the gold wire is welded to the pin of the OECT sensor, and the other end is connected to an external circuit or circuit board. The wire connection needs to be firm and reliable to ensure stable signal transmission. Place the shielding material precisely on the detection area and fix it using an appropriate fixing method. The shielding operation needs to ensure that the shielding material does not interfere with or affect other parts of the OECT sensor. Select potting materials with excellent insulation, corrosion resistance and mechanical strength, such as epoxy resin, silicone rubber, etc. These materials should also have good electromagnetic compatibility (EMC) performance to reduce the influence of external electromagnetic interference on the OECT sensor. Inject the potting material evenly into the gaps around or inside the OECT sensor to form a protective barrier. During the potting process, it is necessary to control the amount and injection speed of the potting material to avoid generating bubbles or overflowing. After the potting material is completely cured and reaches the required performance, remove the shielding material that previously shielded the sensitive area. After removal of the shielding, it is necessary to check whether the OECT sensor is damaged or affected. At the same time, clean up the remaining shielding material and potting material to ensure the cleanliness and reliability of the OECT sensor.

[0054] The above-mentioned embodiments further elaborate on the purpose, technical solutions and advantages of the present invention. It should be understood that the above-mentioned embodiments are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made to the present invention within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A high performance organic electrochemical transistor array sensing element, characterized in that: The sensitive element consists of an array of multiple high-performance organic chemical transistors coated with sensitive materials; A single high-performance organic chemical transistor coated with sensitive materials includes: a substrate, a source electrode, a drain electrode, a gate electrode, a gold electrode, a dielectric liquid ball, a P-type organic dielectric layer, and an N-type organic dielectric layer; The source electrode, the drain electrode, the gate electrode and the gold electrode are all arranged on the upper surface of the substrate, and the source electrode is covered with a P-type organic dielectric layer, the P-type organic dielectric layer is connected to the drain electrode, the drain electrode is connected to the N-type organic dielectric layer, the gold electrode is connected to the source electrode, a part of the N-type organic dielectric layer covers the P-type organic dielectric layer, and a part of it covers the drain electrode; through holes are arranged at corresponding positions of the gate electrode and the substrate, and conductive materials are injected into the through holes so that the gate electrode is connected to the bottom of the base electrode; the dielectric liquid ball is arranged at the center point of the organic dielectric layer and covers a part of the gate electrode.

2. A high performance organic electrochemical transistor array sensing element according to claim 1, characterized in that: The substrate adopts a silicon substrate.

3. A high performance organic electrochemical transistor array sensing element according to claim 1, characterized in that: The conductive material is copper.

4. A sensor using a high-performance organic chemical transistor array sensitive element, characterized in that: include: Sensitive components, ASIC circuit chips, packaging substrates, potting materials and leads; The sensitive element adopts the high-performance organic electrochemical transistor array sensitive element described in claim 1; the ASIC circuit chip is arranged on the upper surface of the packaging substrate; the high-performance organic electrochemical transistor array sensitive element is arranged on the upper surface of the ASIC circuit chip and is electrically connected through leads; the potting material is injected into the packaging substrate so that a protective barrier is formed in the gap around the high-performance organic electrochemical transistor array sensitive element to form a sensor.

5. A sensor using a high-performance organic chemical transistor array sensitive element according to claim 4, characterized in that: The connection between the high-performance organic electrochemical transistor array sensitive element and the ASIC circuit chip includes: a plurality of solder balls are arranged at the bottom of the high-performance organic electrochemical transistor array sensitive element, each solder ball is connected to the copper in the through hole of the high-performance organic chemical transistor; a solder pad is arranged on each solder ball, and the high-performance organic electrochemical transistor array sensitive element is connected to the ASIC circuit chip through the solder pad.

6. A sensor using a high-performance organic chemical transistor array sensitive element according to claim 4, characterized in that: The ASIC circuit chip and the packaging substrate are electrically connected through gold wires.

7. A sensor using a high-performance organic chemical transistor array sensitive element according to claim 4, characterized in that: The ASIC circuit chip is a low-power and high-signal-to-noise ratio ASIC circuit.

8. A sensor using a high-performance organic chemical transistor array sensitive element according to claim 7, characterized in that: The ASIC circuit includes a high-performance analog front end AFE and an analog-to-digital conversion circuit ADC; the positive input terminal of the high-performance analog front end AFE is connected to the source of the high-performance organic electrochemical transistor array sensitive element, the negative input terminal of the high-performance analog front end AFE is connected to the drain of the high-performance organic electrochemical transistor array sensitive element, and the output terminal of the high-performance analog front end AFE is connected to the output terminal of the analog-to-digital conversion circuit ADC.

9. A sensor using a high-performance organic chemical transistor array sensitive element according to claim 8, characterized in that: The analog-to-digital conversion circuit ADC includes: an extraction circuit S / H, a digital-to-analog converter DAC, a successive approximation analog-to-digital converter SAR ADC and a comparator; the input end of the extraction circuit S / H is connected to the input signal V IN The output of the extraction circuit S / H is connected to the positive input of the comparator; the input of the digital-to-analog converter DAC is input with the reference voltage V REF The bias end of the digital-to-analog converter DAC is connected to the output end of the successive approximation analog-to-digital converter SAR ADC, and the output end of the digital-to-analog converter DAC is connected to the negative input end of the comparator; the output end of the comparator is connected to the first input end of the successive approximation analog-to-digital converter SAR ADC and serves as the output end of the ADC; the second input end of the successive approximation analog-to-digital converter SAR ADC is connected to the clock signal CLK.

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