Pluggable composite ion detector based on OECT array and preparation method thereof

Abstract

The invention discloses a pluggable composite ion detector based on an OECT array and a preparation method of the pluggable composite ion detector, and belongs to the technical field of organic electrochemical transistors. The detector comprises a substrate, a source line, a semiconductor layer, a drain line, a packaging layer, an ion driving layer, a sodium ion selective membrane, a potassium ion selective membrane, a calcium ion selective membrane and a protective layer. In addition, the invention also provides a preparation method of the plug-in composite ion detector based on the OECT array. According to the invention, an innovative pluggable composite ion detection scheme is introduced in a breakthrough manner, and high-precision real-time monitoring of the ion concentration in a liquid sample is realized. According to the technology, through the unique principle and method, a major breakthrough is achieved in the field of biomedical research, and the range and depth of biomedical research are remarkably expanded. The invention opens up a brand new application way in key fields of drug screening, disease diagnosis and the like, and provides an efficient, accurate and innovative solution.

Description

Technical Field

[0001] The present invention belongs to the technical field of organic electrochemical transistors, and in particular relates to a plug-in composite ion detector based on an organic electrochemical transistor (OECT) array and a preparation method thereof. Background Art

[0002] Organic Electrochemical Transistor (OECT) has a simple preparation process, low energy consumption characteristics and flexible design. It has emerged in the field of organic electronics and is hailed as a rising star. The high sensitivity, low operating voltage and high transconductance of OECT make it an ideal choice for detecting biochemical signals, especially in the field of health detection. It shows broad application prospects. What is particularly striking is that OECT can be prepared into a variety of forms and sizes according to different designs and manufacturing processes, which gives them the ability to adapt to different application scenarios, such as realizing specific detection and real-time monitoring of metabolites and biomarkers in organisms. This unique advantage makes OECT show great application potential in many cutting-edge fields such as biochemical sensors, neural interface devices and neuromorphic computing.

[0003] The OECT array is a precision micro-array composed of many independent OECTs, each transistor of which can operate alone or work together with other transistors to achieve specific detection tasks. This array has broad application potential in the fields of monitoring and detection. In the design of the plug-in composite ion detector of the OECT array, the key technology is to ensure the excellent stability of the probe detector, so that it can be fully immersed in the detection liquid and maintain long-term ion detection stability. By finely dividing the working area inside the array, this technology can achieve sensitive sensing of multiple ions, thereby providing a variety of ion detection areas in a single array, enhancing the accuracy and flexibility of detection. This design not only improves the detection efficiency, but also expands the application range of the OECT array in complex sample analysis, providing strong technical support for high-precision ion monitoring. In addition, the external circuit in the plug-in composite ion detection technology of the OECT array can independently drive each transistor in the array, which brings great flexibility in device control. At present, there are still several problems with ion concentration detection technology. First, the thickness of ion selective membranes prepared by traditional processes is not uniform and stable enough. Second, traditional transistors are not sensitive enough in ion detection, making it difficult to accurately identify and quantitatively analyze specific ions in body fluids. Third, traditional ion detection technology faces cost-effectiveness challenges, with expensive equipment investment and a long detection cycle, which limits its popularity in rapid detection and large-scale applications.

[0004] The application of pluggable composite ion detectors of OECT arrays in the detection field marks a wave of interdisciplinary innovation, which integrates research results from multiple fields such as materials science, electronic engineering and biomedicine. The exploration of this field not only heralds the frontier of scientific and technological innovation, but is also expected to become a new engine leading the development of future technologies, showing great development potential and broad application prospects. Summary of the invention

[0005] The purpose of the present invention is to provide a plug-in composite ion detector based on an organic electrochemical transistor (OECT) array and a preparation method thereof, so as to solve the technical problems in the prior art that traditional transistors have insufficient sensitivity in ion detection, are difficult to accurately identify and quantitatively analyze specific ions in body fluids, and have high costs.

[0006] In order to solve the above technical problems, the specific technical solutions of the present invention are as follows:

[0007] A plug-in composite ion detector based on an OECT array, the detector comprising a substrate, a source line, a semiconductor layer, a drain line, a packaging layer, an ion drive layer, a sodium ion selective membrane, a potassium ion selective membrane, a calcium ion selective membrane and a protective layer;

[0008] A rectangular strip source line is arranged on the surface of a substrate with three parallel microneedle protrusions. The source line is close to the horizontal center position of the top of each microneedle protrusion on the substrate, extends vertically upward along one side of the microneedle protrusion on the substrate, penetrates the substrate, and is exposed at the other end of the substrate; the surface of the source line at the top of the microneedle protrusion is accurately covered with a square semiconductor layer, and the width of the semiconductor layer is greater than the width of the source line; a drain line is arranged on the central surface of the semiconductor layer, starting from the surface of the semiconductor layer, and extending vertically upward along one side of the microneedle protrusion of the substrate, The drain line penetrates the substrate and is exposed at the other end of the substrate; the source line and the drain line at the top of the microneedle protrusion are perpendicular to each other; the width of the drain line is less than the width of the semiconductor layer, and the drain line does not completely cover or block the semiconductor part; an encapsulation layer is arranged in the top area of ​​the microneedle protrusion of the substrate, and a square hole is arranged in the center of the encapsulation layer to expose the semiconductor layer located at the mutually perpendicular intersection position of the drain line and the source line; the substrate with three parallel microneedle protrusions forms three basic OECT devices by arranging source lines, semiconductor layers, drain lines and encapsulation layers;

[0009] An ion driving layer is arranged on the surface of the encapsulation layer, covering the working area of ​​the top of the microneedle protrusion; the three basic OECT devices covered with the ion driving layer are respectively covered with sleeve-shaped sodium ion selective membrane, potassium ion selective membrane and calcium ion selective membrane, forming three OECT devices with the ability to selectively detect specific ions; a surrounding sealing protective layer is arranged at the open ends of the sodium ion selective membrane, potassium ion selective membrane and calcium ion selective membrane, that is, the end of the sleeve structure; after the three OECT devices with the ability to selectively detect specific ions are provided with the sealing protective layer, a multifunctional OECT array is formed.

[0010] Furthermore, the size of each individual OECT device does not exceed 10 µm × 10 µm; during the process of ion concentration detection, the OECT array is inserted into the test liquid so that the device in each working area can independently detect specific ions.

[0011] Furthermore, the substrate is one of glass, silicon wafer, polyethylene terephthalate PET, polyethylene naphthalate PEN, polydimethylsiloxane PDMS or polyurethane PU.

[0012] Furthermore, the electrode width of the source line and the drain line ranges from 1 to 10 µm, the interval between parallel source lines or drain lines is 1 to 100 µm, the source line and the drain line are made of electrochemically stable conductive materials; the gate is made of electrochemically active or inactive conductive materials.

[0013] Furthermore, the semiconductor layer has a thickness of 10 to 200 nm and is made of a composite semiconductor material having both ion conductivity and electron conductivity, such as poly[thiophene-bis(2-(2-(2-methoxyethoxy)ethoxy)ethoxy)-2,2'-bithiophene], poly[2,5-bis(2,5,8,11,14-pentaoxa-16)-3,6-bis(thiophene-2)-2,5-dihydropyrrole (3,4)pyrrole-1,4-dione], poly[thiophene-bis(2-(2-(2-methoxyethoxy)ethoxy)ethoxy)-2,2'-bithiophene], poly(benzimidazole dibenzophenanthroline) or polyethylene glycol (diol) diacrylate.

[0014] Furthermore, the encapsulation layer is made of an electrochemically stable insulating material, specifically one of Parylene-C, cellulose, photoresist SU-8, polystyrene, polydimethylsiloxane PDMS, and polystyrene-ethylene-butylene SEBS.

[0015] Furthermore, the ion driving layer is made of a high-efficiency ion electrolyte material, specifically one of poly(sodium 4-styrene sulfonate), polyethylene dioxythiophene or polyaniline.

[0016] Furthermore, the sodium ion selective membrane adopts sodium ions and tetrahydrofuran, high molecular weight PVC, bis(2-ethylhexyl) plasticizing solvent intermediary, and bis(2-ethylhexyl) plasticizing solvent; the potassium ion selective membrane adopts potassium ions and tetrahydrofuran, high molecular weight PVC, and bis(2-ethylhexyl) plasticizing solvent; and the calcium ion selective membrane adopts calcium ions and tetrahydrofuran, high molecular weight PVC, and bis(2-ethylhexyl) plasticizing solvent.

[0017] Furthermore, the protective layer is made of a material with electrochemical stability and protective effect, specifically AR9403 transparent adhesive.

[0018] In addition, the present invention also proposes a method for preparing a plug-in composite ion detector based on an OECT array, the method comprising the following steps:

[0019] Step S1: using isopropyl alcohol to ultrasonically clean the substrate having three parallel microneedle protrusions; after cleaning, performing ultraviolet ozone treatment;

[0020] Step S2: Evaporation is performed on the top and side of each microneedle protrusion of the substrate, firstly depositing 3 nm thick chromium; then, 150 nm thick gold is evaporated on the chromium to form a source line;

[0021] Step S3: performing UV-ozone cleaning again on the substrate on which a layer of source lines is deposited;

[0022] Step S4: preparing a semiconductor layer by spin coating;

[0023] Step S5: On the surface of the semiconductor layer and the side of the microneedle protrusion, a 150 nm thick gold layer is prepared as a drain line by evaporation process;

[0024] Step S6: spin coating to prepare an encapsulation layer; three substrates with parallel microneedle protrusions are used to form three basic OECT devices by preparing source lines, semiconductor layers, drain lines and encapsulation layers;

[0025] Step S7: preparing an ion driving layer by spin coating;

[0026] Step S8: preparing a sodium ion selective membrane, a potassium ion selective membrane, and a calcium ion selective membrane; inserting three basic OECT devices covered with an ion driving layer into the sleeve-shaped sodium ion selective membrane, the potassium ion selective membrane, and the calcium ion selective membrane, respectively, and completely covering most areas of the microneedle protrusion structure;

[0027] Step S9: A surrounding sealing protective layer is prepared at the open ends of the sodium ion selective membrane, the potassium ion selective membrane, and the calcium ion selective membrane, i.e., the ends of the sleeve-like structure, to form a multifunctional OECT array, thereby preparing a plug-in composite ion detector based on the OECT array.

[0028] Compared with the prior art, the present invention has the following beneficial technical effects:

[0029] 1) On the one hand, the present invention ensures that a single OECT device has a uniform ion selective membrane and a highly stable protective layer, and on the other hand, further improves the sensitivity of the OECT array in ion concentration detection. The plug-in composite ion detector of the OECT array of the present invention not only significantly improves the working efficiency of each device in the OECT array, but also realizes high-precision simultaneous detection of multiple ions through a single sensor.

[0030] 2) The plug-in OECT array composite ion detector used in the present invention performs well in reducing energy consumption and heat release, while achieving higher transconductance and better detection accuracy. In terms of external circuit design, the present invention effectively avoids the limitations of traditional single drive and reading circuits, and uses structural advantages to accurately read and monitor the signals of specific OECTs. The OECT array ion detection technology of the present invention shows obvious advantages in terms of accuracy, occupied area, energy consumption, driving flexibility, and signal amplification accuracy, fully meeting the detection needs based on the OECT array.

[0031] 3) With vertical structure devices, the channel length can be controlled and adjusted in the range of 1 ~ 10 µm, and the various indicators of the transistor, such as current density, switching rate, capacitance, etc., can be adjusted according to the channel length;

[0032] 4) Using an organic semiconductor layer, under the action of the gate voltage, the ions in the electrolyte layer are doped into or precipitated into the semiconductor, effectively controlling the carrier concentration in the semiconductor and changing the conductivity of the semiconductor;

[0033] 5) The ion selective membrane prepared by the sleeve structure can accurately control the thickness of the ion selective membrane, thereby significantly improving the accuracy of the detection signal;

[0034] 6) The protective layer with a surrounding sealing structure design can significantly enhance the effectiveness of the protective layer and ensure that the detection equipment has excellent long-term stability in the liquid to be tested;

[0035] 7) The use of plug-in detection technology can significantly improve detection efficiency and ensure the accuracy of detection results;

[0036] 8) When preparing the drain line, the present invention can effectively avoid the contact between the drain and the source, thereby avoiding the short circuit of the device; at the same time, the structure is suitable for a variety of electrode preparation methods, including evaporation, sputtering, etc.;

[0037] 9) The plug-in composite ion detection method based on the OECT array provided by the present invention can simultaneously detect and analyze the concentration of multiple ions on a micrometer scale, thereby having the ability to observe and analyze human blood and waste fluid;

[0038] 10) This invention proposes an innovative plug-in composite ion detection technology based on OECT array. This technology allows the detection of a variety of different ions by replacing specific ion carriers in the ion selective membrane. This method significantly reduces the cost of manufacturing and design, while improving the preparation speed and efficiency of OECT ion sensors.

[0039] 11) This invention introduces a revolutionary plug-in composite ion detection scheme, which realizes high-precision real-time monitoring of ion concentration in liquid samples. This innovation not only broadens the boundaries of biomedical research, but also opens up new application paths in fields such as drug screening and disease diagnosis. It brings unprecedented detection tools and methods to clinical research, heralding a revolution in the fields of medicine and life sciences. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative labor.

[0041] Figure 1 It is a front cross-sectional view, a bottom view and a top view of the plug-in type composite ion detector based on the OECT array of the present invention.

[0042] Figure 2 It is a front view and a bottom view of the layered structure of the plug-in type composite ion detector based on the OECT array of the present invention.

[0043] Figure 3 It is the transfer characteristic curve of the output current.

[0044] Figure 4 It is the detection curve of different ion concentrations.

[0045] Markings in the figure: 1-substrate; 2-source line; 3-semiconductor layer; 4-drain line; 5-packaging layer; 6-ion drive layer; 7-sodium ion selective membrane; 8-potassium ion selective membrane; 9-calcium ion selective membrane; 10-protective layer; 11-detection liquid; 12-gate; 13-circuit probe clip. DETAILED DESCRIPTION

[0046] 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.

[0047] The present invention proposes a plug-in composite ion detector based on an OECT array, such as Figure 1-Figure 2 As shown, the detector includes a substrate 1, a source line 2, a semiconductor layer 3, a drain line 4, a packaging layer 5, an ion driving layer 6, a sodium ion selective membrane 7, a potassium ion selective membrane 8, a calcium ion selective membrane 9 and a protective layer 10.

[0048] Figure 1 (a), (b), and (c) are respectively a front cross-sectional view, a bottom view, and a top view of the plug-in type composite ion detector based on the OECT array of the present invention. Figure 2 It is a front view and a bottom view of the layered structure of the plug-in type composite ion detector based on the OECT array of the present invention.

[0049] exist Figure 2 A rectangular strip-shaped source line 2 is arranged on the surface of a substrate 1 having three parallel microneedle protrusions as shown in (a). The source line 2 is close to the horizontal center position of the top of each microneedle protrusion on the substrate 1, extends vertically upward along one side of the microneedle protrusion on the substrate 1, penetrates the substrate 1, and is exposed at the other end of the substrate, as shown in FIG. Figure 2 As shown in (b) in Figure 2 As shown in (c), the surface of the source line 2 at the top of the microneedle protrusion is precisely covered with a square semiconductor layer 3, and the width of the semiconductor layer 3 is greater than the width of the source line 2. Figure 2 As shown in (d), a drain line 4 is provided on the central surface of the semiconductor layer 3. The drain line 4 starts from the surface of the semiconductor layer 3 and extends vertically upward along one side of the microneedle protrusion of the substrate 1 (adjacent to the source line 2 but located on a different side). The drain line 4 penetrates the substrate 1 and is exposed at the other end of the substrate to achieve external connection. The source line 2 and the drain line 4 at the top of the microneedle protrusion are perpendicular to each other. The width of the drain line 4 is smaller than the width of the semiconductor layer 3, and the drain line 4 does not completely cover or block the semiconductor part. Figure 2As shown in (e), a packaging layer 5 is provided at the top area of ​​the microneedle protrusion of the substrate 1, and a square hole is provided in the center of the packaging layer 5 to expose the semiconductor layer located at the perpendicular intersection of the drain line and the source line. The three parallel microneedle protrusion substrates are provided with source lines 2, semiconductor layers 3, drain lines 4 and packaging layers 5 to form three basic OECT devices.

[0050] The size of each individual OECT device does not exceed 10 µm × 10 µm. During the ion concentration detection process, the OECT array is inserted into the test liquid, so that the device in each working area can independently detect specific ions.

[0051] like Figure 2 As shown in (f) in FIG. 5 , an ion driving layer 6 is provided on the surface of the encapsulation layer 5 to cover the working area at the top of the microneedle protrusion. Figure 2 As shown in (g), the three basic OECT devices covered with the ion driving layer 6 are respectively covered with a sleeve-shaped sodium ion selective membrane 7, a potassium ion selective membrane 8, and a calcium ion selective membrane 9, forming three OECT devices with the ability to selectively detect specific ions. Figure 2 As shown in (h), at the open ends of the sodium ion selective membrane 7, the potassium ion selective membrane 8, and the calcium ion selective membrane 9, i.e., at the ends of the sleeve structure, a surrounding sealing protective layer 10 is provided to ensure the stability and sealing of the selective membrane. After the three OECT devices having the ability to selectively detect specific ions are provided with a sealing protective layer, a multifunctional OECT array is formed, i.e., a plug-in composite ion detector based on an OECT array proposed by the present invention.

[0052] The plug-in composite ion detector based on the OECT array proposed in the present invention is detected in the following manner:

[0053] like Figure 2 As shown in (i) in FIG. 1 , the multifunctional OECT array working area is completely immersed in the liquid to be detected 11. Figure 2 As shown in (j) in FIG. 1 , the gate 12 is partially inserted into the liquid 11 to be detected, ensuring that it is in full contact with the liquid 11 to be detected, while the other part of the gate is left outside the liquid for electrical connection and control. Figure 2 As shown in (k), at the exposed ends of the source line 2 and the drain line 4 penetrating the substrate 1, an external circuit probe clip 13 is applied for connection; a voltage signal is applied to the gate 12 and the drain line 4, the source line 2 is grounded, and under the action of the gate voltage and the source-drain voltage between the drain line 4 and the source line 2, the ions in the liquid to be detected 11 can drive the ions in the ion driving layer to penetrate into or precipitate out of the semiconductor layer, thereby realizing the detection of the ion concentration in the liquid to be detected on the surface of the OECT array device.

[0054] The plug-in composite ion detector based on the OECT array is detected through an external circuit, which includes a gate drive module, a drain drive module, a current signal acquisition module, and a voltage signal reading module. The gate drive module is connected to the gate of the OECT array, and a DC bias voltage is applied by a digital-to-analog converter; the drain drive module is connected to the drain line electrode end of the OECT array in a one-to-one correspondence, and according to the ion detection requirements, a MUX analog multiplexer is used to select one of the multiple drain lines in the OECT array, and a DC bias voltage is applied by a digital-to-analog converter; the current signal acquisition module is connected to the source line electrode end of the OECT array in a one-to-one correspondence, and is used to collect the current output by the multiple source lines in the OECT array; the voltage signal reading module is connected to the output end of the current signal acquisition module in a one-to-one correspondence, and an analog-to-digital converter is used to collect the voltage output by the current signal acquisition module after the transconductance amplifier.

[0055] The external circuit can interact with all devices in the OECT array. The interaction is defined as realizing the gating control and reading operation of any single OECT device by defining the combination of rows and columns, that is, driving a single OECT device by applying gate and drain voltages, and obtaining a readable voltage signal through source current collection and transconductance amplification. The external circuit has the ability to configure logic codes, and can flexibly set and adjust the combination of rows and columns according to different detection requirements to realize the gating control and reading of specific OECT devices, thereby achieving the effect of OECT array signal collection.

[0056] Furthermore, the substrate is one of glass, silicon wafer, polyethylene terephthalate PET, polyethylene naphthalate PEN, polydimethylsiloxane PDMS or polyurethane PU.

[0057] Furthermore, the electrode width of the source line and the drain line ranges from 1 to 10 µm, and the interval between parallel source lines or drain lines is 1 to 100 µm. The source line and the drain line are made of electrochemically stable conductive materials, specifically one of gold, platinum, carbon nanotubes or graphene; the gate is made of a conductive material with or without electrochemical activity, specifically one of gold, silver, poly (3,4-ethylenedioxythiophene): polystyrene sulfonate, carbon nanotubes, graphene, and graphyne.

[0058] Furthermore, the semiconductor layer has a thickness of 10 to 200 nm and is made of a composite semiconductor material having both ion conductivity and electron conductivity, such as poly[thiophene-bis(2-(2-(2-methoxyethoxy)ethoxy)ethoxy)-2,2'-bithiophene], poly[2,5-bis(2,5,8,11,14-pentaoxa-16)-3,6-bis(thiophene-2)-2,5-dihydropyrrole (3,4)pyrrole-1,4-dione], poly[thiophene-bis(2-(2-(2-methoxyethoxy)ethoxy)ethoxy)-2,2'-bithiophene], poly(benzimidazole dibenzophenanthroline) or polyethylene glycol (diol) diacrylate.

[0059] Furthermore, the encapsulation layer is made of an electrochemically stable insulating material, specifically one of Parylene-C, cellulose, photoresist SU-8, polystyrene, polydimethylsiloxane PDMS, and polystyrene-ethylene-butylene SEBS.

[0060] Furthermore, the ion driving layer is made of a high-efficiency ion electrolyte material, specifically one of poly(sodium 4-styrene sulfonate), polyethylene dioxythiophene or polyaniline.

[0061] Furthermore, the sodium ion selective membrane, potassium ion selective membrane, and calcium ion selective membrane are made of electrochemically stable materials. Specifically, the sodium ion selective membrane uses sodium ions and tetrahydrofuran, high molecular weight PVC, bis(2-ethylhexyl) plasticizing solvent intermediary, and bis(2-ethylhexyl) plasticizing solvent; the potassium ion selective membrane uses potassium ions and tetrahydrofuran, high molecular weight PVC, and bis(2-ethylhexyl) plasticizing solvent; and the calcium ion selective membrane uses calcium ions and tetrahydrofuran, high molecular weight PVC, and bis(2-ethylhexyl) plasticizing solvent.

[0062] Furthermore, the protective layer is made of a material with electrochemical stability and protective effect, specifically AR9403 transparent adhesive.

[0063] Furthermore, the test fluid is selected to be a solution similar to human body fluids, mainly containing potassium ions, calcium ions, magnesium ions, sodium ions, phosphate ions, etc.

[0064] In combination with the above materials, the preparation method of a plug-in composite ion sensor based on an OECT array of the present invention is described in detail below, which specifically includes the following steps:

[0065] Step S1: Ultrasonic cleaning using isopropyl alcohol Figure 2The substrate with three parallel microneedle protrusions shown in (a) is treated with UV-ozone for 15 minutes to remove dirt and organic matter on the surface. After cleaning, the substrate is further cleaned and disinfected by the synergistic effect of UV and ozone, and the treatment time is also 15 minutes.

[0066] Step S2: On the cleaned substrate with three parallel microneedle protrusions, the top and side surfaces of each microneedle protrusion are evaporated, and 3 nm thick chromium is first deposited to enhance the adhesion of the gold layer. Subsequently, 150 nm thick gold is evaporated on the chromium to form a source line with a width of 10 µm, as shown in FIG. Figure 2 As shown in (b) in .

[0067] Step S3: The substrate with a layer of source lines deposited thereon is again subjected to an ultraviolet ozone cleaning treatment for about 15 minutes.

[0068] Step S4: Spin coating to prepare a semiconductor layer: control the humidity below 10%, spin-coat the top area of ​​the microneedle protrusions on the substrate with a semiconductor material at a rotation speed of 3000 rpm, and the spin coating time is 10 s; photolithography: strictly align the photolithography mask with the substrate coated with the organic semiconductor layer material, use 365 nm ultraviolet light to photolithography the semiconductor film at the channel to cross-link it, and wash away the uncross-linked part to form a semiconductor layer in the channel area, such as Figure 2 As shown in (c) in .

[0069] Step S5: On the surface of the semiconductor layer and the side of the microneedle protrusion, a 150 nm thick gold layer is prepared as a drain line by evaporation process, and the width of the drain line is 10 μm, as shown in FIG. Figure 2 As shown in (d) in .

[0070] Step S6: Spin coating to prepare the encapsulation layer: control the humidity below 10%, and spin-coat the encapsulation layer material on the top area of ​​the microneedle protrusion on the substrate at a rotation speed of 3000 rpm, and the spin coating time is 10 s; Photolithography: strictly align the photolithography mask with the substrate coated with the encapsulation layer material, and use 365 nm ultraviolet light to photolithograph the encapsulation layer material outside the central position where the drain line and the source line cross each other perpendicularly to make it cross-linked, and wash away the uncross-linked part to expose the semiconductor layer located at the central position where the drain line and the source line cross each other perpendicularly, such as Figure 2 As shown in (e) in the figure, three parallel microneedle-protruded substrates are used to form three basic OECT devices by preparing source lines, semiconductor layers, drain lines and encapsulation layers.

[0071] Step S7: Spin coating to prepare the ion driving layer: The humidity was controlled below 10%, and the top area of ​​the microneedle protrusions on the substrate was spin coated at a speed of 3000 rpm to evenly coat the ion driving layer material. The spin coating time was 10 s. Then, the spin-coated substrate was dried at 130°C for 1 hour to form the ion driving layer. Figure 2 As shown in (f) in .

[0072] Step S8: Preparation of sodium ion selective membrane, potassium ion selective membrane, and calcium ion selective membrane: The three sleeve-shaped molds are immersed in the electrolyte containing sodium ion selective membrane material, potassium ion selective membrane material, and calcium ion selective membrane material, respectively, and then quickly pulled out to ensure that the outer walls of the three molds are uniformly covered with a layer of sodium ion selective membrane material, potassium ion selective membrane material, and calcium ion selective membrane material, and dried at 50 ° C for 10 min, and finally peeled off the sodium ion selective membrane, potassium ion selective membrane, and calcium ion selective membrane from the outer wall of the mold to form a sleeve-shaped sodium ion selective membrane, potassium ion selective membrane, and calcium ion selective membrane. The three basic OECT devices covered with the ion driving layer are respectively inserted into the sleeve-shaped sodium ion selective membrane, potassium ion selective membrane, and calcium ion selective membrane to ensure that the sodium ion selective membrane, potassium ion selective membrane, and calcium ion selective membrane are tightly fitted with the OECT device and completely cover most of the area of ​​the microneedle protrusion structure.

[0073] Step S9: A surrounding sealing protective layer is prepared at the open ends of the sodium ion selective membrane, the potassium ion selective membrane, and the calcium ion selective membrane, i.e., the ends of the sleeve-like structure, to form a multifunctional OECT array, thereby preparing a plug-in composite ion detector based on the OECT array, such as Figure 2 As shown in (h) in .

[0074] Furthermore, when detecting the composite ions, the following steps are performed:

[0075] Step S10: insert the working area covered with the sodium ion selective membrane, potassium ion selective membrane, and calcium ion selective membrane into the liquid to be tested as an electrolyte layer, and connect the gate through the liquid to be tested, such as Figure 2 As shown in (i) and (j) in .

[0076] Step S11: Apply external circuit probe clamps at the ends of the source and drain lines to detect multiple ions simultaneously, such as Figure 2 As shown in (k) in .

[0077] In this embodiment, the source line, the drain line, and the gate are prepared by one of evaporation, magnetron sputtering, spraying, inkjet printing, aerosol printing, screen printing, and laser engraving. The semiconductor layer, the encapsulation layer, and the electrolyte layer are prepared by one of spin coating, spraying, screen printing, inkjet printing, 3D printing, aerosol printing, electrofluid printing, or scraping.

[0078] Next, we use the source meter to test the plug-in composite ion detector of the prepared OECT array. The test conditions are as follows:

[0079] Under the condition of constant drain voltage (Vd = -0.1 V), the transfer characteristics of the source output current of a single device in the OECT array are captured under a positive sweep of the gate voltage range from 0 V to +0.8 V, and the transfer characteristic curve is plotted, as shown in Figure 2. Figure 3 As shown in the figure, it can be seen that under this test condition, the plug-in composite ion detector of the OECT array shows an excellent current regulation effect. The source current (solid line) can be controlled from 10-8 A to 10-2 A, and its transfer characteristics have good consistency.

[0080] For cation detection, the gate-source voltage was scanned from +0.1 V to +0.8 V in a positive direction under a constant drain voltage (Vd = 0.1 V) to capture the transfer characteristics of the output current of a single OECT device in the entire array, and the transfer characteristic curve was plotted, as shown in Fig. Figure 4 As shown in the figure, it can be seen that under this test condition, the plug-in composite ion detector of the OECT array exhibits an excellent current regulation effect, and its on-state current increases with the increase of the corresponding ion concentration, while the gate current remains at a low level (<10-5 A). Figure 4 (a), (b) and (c) are the concentration detection curves of sodium ions, potassium ions and calcium ions, respectively. Figure 4 In (a), the solid line represents the transfer characteristic curve of a single OECT device with a sodium ion selective membrane detecting sodium ion solutions of different concentrations, while the dotted line represents the transfer characteristic curve when detecting potassium ion and calcium ion solutions of different concentrations. Figure 4 (b) shows the transfer characteristic curves of a single OECT device with a potassium ion selective membrane in ion solutions of different concentrations, where the solid line corresponds to potassium ions and the dotted lines correspond to sodium ions and calcium ions. Figure 4 (c) shows the transfer characteristic curves of the OECT device with a calcium ion selective membrane in ion solutions of different concentrations, where the solid line corresponds to calcium ions and the dotted lines correspond to sodium ions and potassium ions. These curves clearly show the selective response of the OECT device combined with a specific ion selective membrane to specific ions.

[0081] It is to be understood that the present invention is described by some embodiments, and it is known to those skilled in the art that various changes or equivalent substitutions may be made to these features and embodiments without departing from the spirit and scope of the present invention. In addition, under the teachings of the present invention, these features and embodiments may be modified to adapt to specific circumstances and materials without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the scope of protection of the present invention.

Claims

1. A plug-in composite ion detector based on an OECT array, characterized in that: The detector comprises a substrate, a source line, a semiconductor layer, a drain line, a packaging layer, an ion driving layer, a sodium ion selective membrane, a potassium ion selective membrane, a calcium ion selective membrane and a protective layer; A rectangular strip source line is arranged on the surface of a substrate with three parallel microneedle protrusions. The source line is close to the horizontal center position of the top of each microneedle protrusion on the substrate, extends vertically upward along one side of the microneedle protrusion on the substrate, penetrates the substrate, and is exposed at the other end of the substrate; the surface of the source line at the top of the microneedle protrusion is accurately covered with a square semiconductor layer, and the width of the semiconductor layer is greater than the width of the source line; a drain line is arranged on the central surface of the semiconductor layer, starting from the surface of the semiconductor layer, and extending vertically upward along one side of the microneedle protrusion of the substrate, The drain line penetrates the substrate and is exposed at the other end of the substrate; the source line and the drain line at the top of the microneedle protrusion are perpendicular to each other; the width of the drain line is less than the width of the semiconductor layer, and the drain line does not completely cover or block the semiconductor part; an encapsulation layer is arranged in the top area of ​​the microneedle protrusion of the substrate, and a square hole is arranged in the center of the encapsulation layer to expose the semiconductor layer located at the mutually perpendicular intersection position of the drain line and the source line; the substrate with three parallel microneedle protrusions forms three basic OECT devices by arranging source lines, semiconductor layers, drain lines and encapsulation layers; An ion driving layer is provided on the surface of the encapsulation layer, covering the working area of ​​the top of the microneedle protrusion; The three basic OECT devices covered with an ion driving layer are respectively covered with a sleeve-shaped sodium ion selective membrane, a potassium ion selective membrane, and a calcium ion selective membrane, to form three OECT devices with the ability to selectively detect specific ions; a surrounding sealing protective layer is set at the open ends of the sodium ion selective membrane, the potassium ion selective membrane, and the calcium ion selective membrane, that is, the end of the sleeve structure; after the three OECT devices with the ability to selectively detect specific ions are set with a sealing protective layer, a multifunctional OECT array is formed.

2. The plug-in composite ion detector based on the OECT array according to claim 1, characterized in that: The size of each individual OECT device does not exceed 10 µm × 10 µm; during the ion concentration detection process, the OECT array is inserted into the test liquid so that the device in each working area can independently detect specific ions.

3. The plug-in composite ion detector based on OECT array according to claim 1, characterized in that: The substrate is one of glass, silicon wafer, polyethylene terephthalate PET, polyethylene naphthalate PEN, polydimethylsiloxane PDMS or polyurethane PU.

4. The plug-in composite ion detector based on the OECT array according to claim 1, characterized in that: The electrode width of the source line and the drain line ranges from 1 to 10 µm, the interval between parallel source lines or drain lines is 1 to 100 µm, the source line and the drain line are made of electrochemically stable conductive materials; the gate is made of electrochemically active or inactive conductive materials.

5. The plug-in composite ion detector based on OECT array according to claim 1, characterized in that: The thickness of the semiconductor layer is 10 to 200 nm, and the semiconductor layer is made of a composite semiconductor material that is both ion-conducting and electron-conducting, such as poly[thiophene-bis(2-(2-(2-methoxyethoxy)ethoxy)ethoxy)-2,2'-bithiophene], poly[2,5-bis(2,5,8,11,14-pentaoxa-16)-3,6-bis(thiophene-2)-2,5-dihydropyrrole (3,4)pyrrole-1,4-dione], poly[thiophene-bis(2-(2-(2-methoxyethoxy)ethoxy)ethoxy)-2,2'-bithiophene], poly(benzimidazole dibenzophenanthroline) or polyethylene glycol (diol) diacrylate.

6. The plug-in composite ion detector based on OECT array according to claim 1, characterized in that: The encapsulation layer is made of an electrochemically stable insulating material, specifically one of Parylene-C, cellulose, photoresist SU-8, polystyrene, polydimethylsiloxane PDMS, and polystyrene-ethylene-butylene SEBS.

7. The plug-in composite ion detector based on OECT array according to claim 1, characterized in that: The ion driving layer is made of a high-efficiency ion electrolyte material, specifically one of poly(sodium 4-styrene sulfonate), polyethylene dioxythiophene or polyaniline.

8. The plug-in composite ion detector based on OECT array according to claim 1, characterized in that: The sodium ion selective membrane adopts sodium ions and tetrahydrofuran, high molecular weight PVC, bis(2-ethylhexyl) plasticizing solvent intermediary, and a variety of bis(2-ethylhexyl) plasticizing solvents; the potassium ion selective membrane adopts potassium ions and tetrahydrofuran, high molecular weight PVC, and a variety of bis(2-ethylhexyl) plasticizing solvents; the calcium ion selective membrane adopts calcium ions and tetrahydrofuran, high molecular weight PVC, and a variety of bis(2-ethylhexyl) plasticizing solvents.

9. The plug-in composite ion detector based on OECT array according to claim 1, characterized in that: The protective layer is made of a material with electrochemical stability and protective effect, specifically AR9403 transparent adhesive.

10. A method for preparing a pluggable composite ion detector based on an OECT array, used for preparing the pluggable composite ion detector based on an OECT array according to any one of claims 1 to 9, characterized in that: The method comprises the following steps: Step S1: using isopropyl alcohol to ultrasonically clean the substrate having three parallel microneedle protrusions; after cleaning, performing ultraviolet ozone treatment; Step S2: Evaporation is performed on the top and side of each microneedle protrusion of the substrate, firstly depositing 3 nm thick chromium; then, 150 nm thick gold is evaporated on the chromium to form a source line; Step S3: performing UV ozone cleaning again on the substrate on which a layer of source lines is deposited; Step S4: preparing a semiconductor layer by spin coating; Step S5: On the surface of the semiconductor layer and the side of the microneedle protrusion, a 150 nm thick gold layer is prepared as a drain line by evaporation process; Step S6: spin coating to prepare an encapsulation layer; three substrates with parallel microneedle protrusions are used to form three basic OECT devices by preparing source lines, semiconductor layers, drain lines and encapsulation layers; Step S7: preparing an ion driving layer by spin coating; Step S8: preparing a sodium ion selective membrane, a potassium ion selective membrane, and a calcium ion selective membrane; The three basic OECT devices covered with the ion driving layer are respectively inserted into the sleeve-shaped sodium ion selective membrane, potassium ion selective membrane, and calcium ion selective membrane, and completely cover most areas of the microneedle protrusion structure; Step S9: A surrounding sealing protective layer is prepared at the open ends of the sodium ion selective membrane, the potassium ion selective membrane, and the calcium ion selective membrane, i.e., the ends of the sleeve-like structure, to form a multifunctional OECT array, thereby preparing a plug-in composite ion detector based on the OECT array.

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