Method for constructing organic electrochemical transistor ion sensing devices based on printing techniques

Abstract

The application discloses a method for constructing an organic electrochemical transistor ion sensing device based on a printing technology. The method comprises the following steps: taking a PI film as a flexible substrate of an organic electrochemical transistor, using a silk screen to make an electrode layer on the substrate to obtain the organic electrochemical transistor, then modifying a polyelectrolyte layer on a channel of the organic electrochemical transistor to obtain the polyelectrolyte layer, finally, modifying an ion-selective membrane on the channel of the organic electrochemical transistor with the polyelectrolyte layer to obtain the final organic electrochemical transistor ion sensing device, and exploring the feasibility of the device for ion sensing through a series of electrical characterization methods. The method combines the organic electrochemical transistor technology and the printing technology, prepares the organic electrochemical transistor flexible ion sensing device based on a flexible material substrate, is used for ion content detection, greatly reduces production cost, improves production efficiency, and meets the requirements of device and biological body adaptation and the like.

Description

Technical Field

[0001] This invention relates to a method for fabricating a sensing device in the field of electrochemical transistor technology, and particularly to a method for constructing an organic electrochemical transistor ion sensing device based on printing technology. Background Technology

[0002] Ion concentrations in biological media play a crucial role in the health of every organism. Therefore, the need for accurate, rapid, and low-cost monitoring of these concentrations has spurred the development of ion sensors for biological systems. However, the sensitivity of conventional ion-selective sensors is limited to 59.2 mV / log for the Nernstian response of monovalent ions at 25 °C. 10 [C Ion This basically meets the needs of in vitro ion detection in biological systems. However, given the reality that high ion concentrations and even minor changes in ion concentrations within biological systems can cause significant alterations in health conditions, developing an ion sensing technology with higher sensitivity is crucial. With advancements in science and technology, the emergence of organic electrochemical transistors has provided more possibilities for developing ultra-high sensitivity sensing devices.

[0003] Organic electrochemical transistors (OETTs) function like switches, where the electrochemical state and impedance of the gate electrode control the amount of current in the channel, which is connected to the gate electrode via an electrolyte. Therefore, particularly for biosensing, OETTs have become a valuable tool due to their efficient transduction and amplification effects. OETTs possess relatively simple structures and are easy to manufacture, allowing for the use of electrolytes (solid, gel, liquid) as gates, thus enabling structural diversity. Furthermore, the use of organic materials facilitates the fabrication of OETT devices on various substrates (rigid, flexible, stretchable). These advantages make OETT technology compatible with multiple manufacturing techniques, including photolithography, screen printing, inkjet printing, and spray coating. When selecting a manufacturing technology, various parameters must be carefully considered, such as electrode materials, substrate, device size, cost, uniformity, and electrochemical performance. While photolithography is the standard technology for manufacturing organic bioelectronic devices, it requires multiple cumbersome steps and expensive equipment, making it unsuitable for large-scale production. In contrast, printing technologies such as screen printing, aerosol printing, and inkjet printing offer simpler manufacturing steps and are suitable for flexible materials as substrates, making them ideal for the manufacture of wearable electronic devices. The use of printing technology to fabricate organic electrochemical transistor devices offers several advantages, such as rapid fabrication, low cost, high quality, high customizability, and environmental friendliness. Screen printing, due to its high precision, high efficiency, and versatility, has become one of the most widely used fabrication methods. By adjusting the size and shape of the screen, the amount and distribution of deposited material can be controlled, achieving high-resolution printing. Compared to other printing technologies, screen printing can complete large-area printing in a shorter time, making it suitable for large-scale production needs. Finally, screen printing is applicable to printing on organic materials of different types and properties, and is suitable for fabricating various types of organic electrochemical transistors.

[0004] In recent years, organic materials have become a popular choice for bioelectronic devices such as biosensors and neural implants. The elastic modulus of rigid materials like metals and silicon does not match that of biological tissues, leading to rejection by the immune system. Materials with low elastic modulus are advantageous for devices that connect to other parts of the body, reducing strain response during continuous movement. Therefore, flexible electronics based on flexible materials are increasingly being used to develop wearable electronic skin to supplement or replace the functions of human skin. Currently, photolithography, the standard fabrication method for organic electrochemical transistors, is incompatible with such flexible materials, making it impossible to fabricate flexible devices. Screen printing technology offers a feasible method that can effectively simplify the fabrication process and reduce production costs. However, existing technologies lack a method for fabricating organic electrochemical transistor ion-sensing devices using screen printing technology. Summary of the Invention

[0005] To address the problems existing in the background art, the present invention aims to design a method for constructing an organic electrochemical transistor ion sensing device based on printing technology. This ion sensing device is used for feasibility assessment of in-situ sensing of ion content in animals / plants. The method of this invention combines the modification of ion-selective membranes with the vertical structure design of organic electrochemical transistor devices, significantly improving the feasibility of organic electrochemical transistor ion devices in ion detection applications.

[0006] The technical solution of this invention is as follows, including the following steps:

[0007] Step 1) First, the organic electrochemical transistor is fabricated:

[0008] Step 1.1) Take PI (polyimide) film as the flexible substrate of organic electrochemical transistor. Sonicate the substrate in deionized water and isopropanol for 10-30 min respectively, dry it, and then plasma treat the dried substrate for 4-6 min to obtain the treated substrate, so as to facilitate the subsequent printing of paste.

[0009] Step 1.2) Use a screen printing stencil to create two electrode layers on the substrate;

[0010] Step 1.3) Except for the carbon contact points and sensing channel area, the two electrode layers are coated with insulating ink and then cured with ultraviolet light to obtain an organic electrochemical transistor.

[0011] The sensing channel region is the area where the source electrode, channel layer and drain electrode overlap in the electrode layer, that is, the sensing channel region is mainly formed by the source electrode, channel layer and drain electrode stacked in sequence.

[0012] The purpose of coating and curing with insulating ink is to achieve effective encapsulation of organic electrochemical transistors, protect them from environmental pollution and mechanical damage, and form a complete printed organic electrochemical transistor.

[0013] Step 2) Then, the organic electrochemical transistor channel is modified with a polyelectrolyte layer to obtain a polyelectrolyte layer;

[0014] Step 3) Finally, the ion-selective membrane of the organic electrochemical transistor channel with polyelectrolyte layer is modified to obtain the final organic electrochemical transistor ion sensing device.

[0015] Step 1.2) specifically refers to:

[0016] Step 1.2.1) Obtain two screen printing stencils of specific shapes. Coat the first screen printing stencil with carbon paste. Then, place the first screen printing stencil coated with carbon paste on the substrate and print the first electrode layer on the substrate surface by scraping. The first electrode layer mainly consists of the source electrode and gate electrode of the organic electrochemical transistor. Next, apply conductive silver paste to the areas of the source electrode and gate electrode of the first electrode layer, except for the carbon contact points, to increase the conductivity of the organic electrochemical transistor. At the same time, apply Ag / AgCl paste to the carbon contact points of the gate electrode of the first electrode layer to obtain a substrate coated with conductive silver paste and Ag / AgCl paste.

[0017] Step 1.2.2) The substrate prepared in Step 1.2.1) is subjected to plasma treatment for 4 to 6 minutes. The PEDOT:PSS ((poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid), PH1000) mixture is drop-coated onto the preset channel area and annealed at 100℃ to 120℃ for 1 to 2 hours in an inert environment to obtain the channel layer.

[0018] The channel region is located above the region where the carbon contact point of the source electrode is located.

[0019] Step 1.2.3) Place the second screen printing stencil on the substrate obtained in step 1.2.2), and coat the carbon paste on the surface of the substrate by scraping to obtain the second electrode layer. The second electrode layer is mainly composed of drain electrodes, and the carbon contact point of the drain electrode is located above the carbon contact point of the source electrode. Then, the area on the second electrode layer other than the carbon contact point is coated with conductive silver paste.

[0020] After applying the carbon paste, conductive silver paste, Ag / AgCl paste, or PEDOT:PSS mixture in the above steps, the coatings must be heated at 110℃~130℃ for 8~12 minutes to complete the curing of the coatings.

[0021] Step 2) specifically refers to:

[0022] Step 2.1) First, add DBSA (dodecylbenzenesulfonic acid), GOPS ((3-glycidylpropoxy)trimethoxysilane) and HCl to the PSSNa (sodium poly(4-styrenesulfonate)) aqueous solution, mix and stir until homogeneous to obtain a PSSNa mixed solution, which will be used for subsequent channel modification;

[0023] Step 2.2) Then, using a pipette, 0.3 to 0.6 μL of PSSNa mixed solution is added to the sensing channel region of the organic electrochemical transistor obtained in step 1), and heated at 120°C to 140°C for 1 to 2 hours to perform polyelectrolyte crosslinking, so that a polyelectrolyte layer is generated on the surface of the sensing channel region of the organic electrochemical transistor.

[0024] Step 2.3) Subsequently, the sensing channel region of the organic electrochemical transistor is immersed in NaCl solution for 10–14 h to remove excess PSSNa mixed solution, and then Na is stored in the polyelectrolyte layer. + ;

[0025] Step 2.4) Wash off the excess NaCl solution with deionized water, and then dry the organic electrochemical transistor at room temperature for subsequent modification of the ion-selective membrane to obtain an organic electrochemical transistor with a polyelectrolyte layer.

[0026] Step 3) specifically refers to:

[0027] Step 3.1) Add 150 mg of solute to 1.0 mL of THF solvent to prepare a potassium ion selective membrane solution;

[0028] Step 3.2) Add 0.8–1.2 μL of potassium ion-selective membrane solution to the sensing channel region of the organic electrochemical transistor obtained after drying in Step 2.4) and dry at room temperature. Repeat the addition of potassium ion-selective membrane solution and drying three times to obtain an ion-selective membrane.

[0029] Step 3.3) Apply adhesive to the edge area of ​​the ion-selective membrane and cure at room temperature for more than 1 hour to complete the sealing of the organic electrochemical transistor; the adhesive sealing is to prevent the test solution from entering the ion-selective membrane during testing.

[0030] Step 3.4) Immerse the sealed sensing channel region of the organic electrochemical transistor in KCl solution for 10-14 hours to complete the activation, and finally obtain the organic electrochemical transistor ion sensing device.

[0031] The solute in step 3.1) is a mixture of potassium ion carrier, KTFPB (potassium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate), NPOE (2-nitrophenyl octyl ether), and PVC (polyvinyl chloride).

[0032] The mass percentages of the potassium ion carrier, KTFPB, NPOE, and PVC are 2.5 wt%, 0.5 wt%, 60.5 wt%, and 36.5 wt%, respectively.

[0033] The potassium ion carrier is at least one of the following: valhalamicin, 4-tert-butyl-2,2,14,14-tetraethyl-substituted-2a,14a,dioxo-bridged calix[4] aryl-tetraacetic acid tetratert-butyl ester, bis[(benzo-15-crown-5)-4′-methyl] heptacyanate, and 2-dodecyl-2-methyl-1,3-propadiylbis[N-[5′-nitro(benzo-15-crown-5)-4′-yl]carbamate].

[0034] The aperture size of both the first and second screen printing stencils is 380-420 mesh.

[0035] In step 2.1), the volume ratio of PSSNa to DBSA is 4000:1 to 4500:1, the volume ratio of GOPS to DBSA is 4:1 to 5:1, and the volume ratio of HCl to DBSA is 4:1 to 5:1.

[0036] The vertical structure design of organic electrochemical transistor devices specifically refers to the vertical stacking and intersection of the carbon contact points of the source electrode in the first electrode layer with the carbon contact points of the channel layer and the drain electrode in the second electrode layer, forming a vertically structured organic electrochemical transistor device, such as... Figure 1 As shown.

[0037] Therefore, this invention combines organic electrochemical transistor technology with printing technology to fabricate flexible ion sensing devices based on flexible material substrates. These devices are used for ion content detection, significantly reducing production costs, improving production efficiency, and meeting requirements regarding device compatibility with biological organisms. Simultaneously, the vertical structure design of the source and drain electrodes of the organic electrochemical transistor effectively reduces the area of ​​the device's working region, providing a valuable tool for developing a small, low-cost printed flexible ion sensing device. Furthermore, a series of electrical characterization methods have verified the feasibility of using this device for ion sensing.

[0038] The beneficial effects of this invention are as follows:

[0039] 1. The method of this invention uses screen printing technology to prepare organic chemical transistor devices, which is low in cost and simple to prepare;

[0040] 2. The method of the present invention transforms the relative positions of the source and drain electrodes from horizontal parallel to vertical stacking by designing a vertical structure for organic electrochemical transistor devices, which greatly improves their electrical performance. In addition, it avoids the impact of the resolution limitation of screen printing technology on device performance.

[0041] 3. The method of the present invention prints the gate electrode of the organic electrochemical transistor as a homologous electrode on the first electrode layer, thereby changing the gate electrode structure from the traditional independent type to a coplanar configuration, which makes the operation more convenient and eliminates the need to operate two independent devices.

[0042] 4. The method of the present invention uses flexible materials as a substrate to realize the fabrication of flexible devices, enabling ion sensing devices to be applied to implantable devices and wearable electronic devices.

[0043] 5. This invention combines the modification of ion-selective membranes with the vertical structure design of organic electrochemical transistor devices, which greatly improves the feasibility of organic electrochemical transistor ion devices in ion detection applications. Attached Figure Description

[0044] Figure 1 This is a schematic diagram of the vertical interface structure formed by the vertical stacking of the source electrode carbon contact point, the channel layer, and the drain electrode carbon contact point in this invention.

[0045] Figure 2 The graphs show the transfer characteristic curves and transconductance curves of the unmodified screen-printed organic electrochemical transistor device in this invention.

[0046] Figure 3 This is a characterization diagram of the basic electrical performance of the ion-selective membrane modified screen-printed organic electrochemical transistor device for potassium ions in this invention; where a represents the transfer characteristic curve and b represents the output characteristic curve.

[0047] Figure 4 This is a characterization graph of the sensing performance of adding potassium ion solutions of different concentrations to the buffer solution using the current analysis method in this invention; where a represents the current-time response curve and b represents the calibration curve. Detailed Implementation

[0048] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0049] The implementation process of the embodiments of the present invention is as follows:

[0050] Step 1) First, the organic electrochemical transistor is fabricated:

[0051] Step 1.1) Take the PI film as the flexible substrate of the organic electrochemical transistor, and sonicate the substrate in deionized water and isopropanol for 20 min respectively, dry it, and then perform plasma treatment on the dried substrate for 5 min to obtain the dried substrate for subsequent printing of paste.

[0052] Step 1.2) Use a screen printing stencil to create two electrode layers on the substrate;

[0053] Step 1.2.1) First, carbon paste is coated onto the first screen printing stencil. Then, the first screen printing stencil coated with carbon paste is placed on the substrate. The substrate surface is scraped and cured to obtain the first electrode layer. The first electrode layer mainly consists of the source electrode and the gate electrode of the organic electrochemical transistor. Next, conductive silver paste is coated onto the areas of the source electrode and the gate electrode of the first electrode layer, except for the carbon contact points, and cured to increase the conductivity of the organic electrochemical transistor. At the same time, Ag / AgCl paste is coated onto the carbon contact points of the gate electrode of the first electrode layer and cured to form the final gate electrode.

[0054] Carbon contact points refer to the portion of the source electrode used to construct the subsequent stacked structure and the region of the gate electrode used for modulation.

[0055] Step 1.2.2) Then, the substrate obtained in step 1.2.1) above is subjected to plasma treatment for 5 minutes, and the PEDOT:PSS mixture is drop-coated onto the preset channel area. It is then annealed and cured at 120°C for 1.5 hours in an inert environment to obtain the channel layer. The channel layer is located above the area where the source electrode is located.

[0056] Step 1.2.3) Subsequently, the second screen printing stencil is placed over the substrate obtained in step 1.2.2), and carbon paste is coated onto the substrate surface by scraping. After curing, the second electrode layer is obtained. The second electrode layer is mainly composed of drain electrodes, and the carbon contact point of the drain electrode is located above the carbon contact point of the source electrode. The channel layer is located between the carbon contact point of the drain electrode and the carbon contact point of the source electrode. Then, conductive silver paste is applied to the area of ​​the second electrode layer other than the carbon contact point and cured.

[0057] After coating the carbon paste, conductive silver paste and PEDOT:PSS mixture in the above steps, the coatings need to be heated at 110℃~130℃ for 8~12 minutes to complete the curing of the coating.

[0058] The source electrode, channel layer, and drain electrode form a vertical structure, such as Figure 1 As shown.

[0059] Step 1.3) All areas of the two electrode layers except for the carbon contact points and the sensing channel region are coated with insulating ink and then cured with ultraviolet light to obtain an organic electrochemical transistor; the sensing channel region is the area where the source electrode, channel layer and drain electrode overlap in the electrode layer.

[0060] The purpose of coating and curing with insulating ink is to achieve effective encapsulation of organic electrochemical transistors, protect them from environmental pollution and mechanical damage, and form a complete printed organic electrochemical transistor.

[0061] After obtaining the organic electrochemical transistor in step 1), 10 μL of PBS buffer was transferred using a pipette and added to the sensing channel region of the organic electrochemical transistor. The basic electrical performance of the organic electrochemical transistor was characterized by semiconductor parameter analysis, including transfer characteristic curves and transconductance curves. Figure 2 As shown in the transfer characteristic curves, the channel current decreases with increasing gate voltage, exhibiting a typical consumption-type operating mode. Furthermore, the gate electrode has a significant regulating effect on the channel within the 0-1.0V test range. In addition, the organic electrochemical transistor exhibits a lower operating voltage. The transconductance curves reflect the effective gating effect of the polymer channel. The experimental results preliminarily demonstrate the feasibility of using printing technology for the fabrication of organic electrochemical transistors.

[0062] Step 2) Then, the organic electrochemical transistor channel is modified with a polyelectrolyte layer to obtain a polyelectrolyte layer;

[0063] Step 2.1) First, add DBSA, GOPS and 1M HCl to a 1.2% w / v PSSNa aqueous solution, mix and stir until homogeneous to obtain a PSSNa mixed solution, which will be used for subsequent channel modification.

[0064] The volume ratio of PSSNa, DBSA, GOPS and HCl is 4000:1:4:4.

[0065] Step 2.2) Then, using a pipette, 0.5 μL of the PSSNa mixed solution was added to the sensing channel region of the organic electrochemical transistor obtained in step 1), and heated at 130 °C for 1 hour to perform polyelectrolyte crosslinking, so that a polyelectrolyte layer was generated on the surface of the sensing channel region of the organic electrochemical transistor.

[0066] Step 2.3) Subsequently, the sensing channel region of the organic electrochemical transistor was immersed in 0.1M NaCl solution for 12 hours to remove excess PSSNa mixed solution, and then Na was stored in the polyelectrolyte layer. + ;

[0067] Step 2.4) Wash off the excess NaCl solution with deionized water, and then dry the organic electrochemical transistor at room temperature for subsequent modification of the ion-selective membrane to obtain an organic electrochemical transistor with a polyelectrolyte layer.

[0068] Step 3) Finally, the ion-selective membrane of the organic electrochemical transistor channel obtained in step 2) is modified to obtain the final organic electrochemical transistor ion sensing device.

[0069] Step 3.1) Add 150 mg of solute to 1.0 mL of THF solvent to prepare a potassium ion selective membrane solution;

[0070] The solute is a mixture of 2.5 wt% 2-dodecyl-2-methyl-1,3-propanediylbis[N-[5′-nitro(benzo-15-crown-5)-4′-yl]carbamate], 0.5 wt% KTFPB, 60.5 wt% NPOE and 36.5 wt% PVC.

[0071] Step 3.2) Add 1.0 μL of potassium ion selective membrane solution to the sensing channel region of the organic electrochemical transistor obtained after drying in step 2.4) and dry at room temperature. Repeat the addition of potassium ion selective membrane solution and drying three times to obtain an ion selective membrane.

[0072] Step 3.3) Apply adhesive to the edge area of ​​the ion-selective membrane and cure at room temperature for more than 1 hour to complete the sealing of the organic electrochemical transistor; the adhesive sealing is to prevent the test liquid from entering the ion-selective membrane.

[0073] Step 3.4) The sensing channel region of the sealed organic electrochemical transistor is subjected to 10 -3 The device was activated by soaking in MgCl solution for 12 hours, and finally obtained as an organic electrochemical transistor ion sensing device.

[0074] Basic electrical characterization tests were performed on the fabricated sensing device in PBS buffer solution:

[0075] 10 μL of PBS buffer was pipetted and added to the sensing channel region and the Ag / AgCl slurry-coated portion of the gate electrode of the prepared organic electrochemical transistor ion sensing device. The basic electrical performance of the device, including transfer and output characteristic curves, was characterized by semiconductor parameter analysis. Figure 3 As shown in curve a, the transfer characteristic curves indicate that the device still exhibits channel control even after modification with an ion-selective film. Furthermore, according to... Figure 3 The output characteristic curve shown in Figure b indicates that the device can reach saturation within the test range. This demonstrates the feasibility of using printed organic electrochemical transistor ion sensing devices to construct ion sensing devices and for practical ion sensing.

[0076] Potassium ions were detected using an organic electrochemical transistor ion sensing device.

[0077] A standard curve for potassium ion detection was constructed. Potassium ion solutions of different concentrations were prepared, and the channel current was measured as the ion concentration increased using galvanometry. First, the device was placed in deionized water, and the channel current was recorded under a constant gate electrode voltage (0.45V) and a fixed source-drain voltage (-0.5V). After the current value stabilized, potassium chloride solutions of different concentrations were added to the solution at 2.0-minute intervals, gradually increasing the potassium ion concentration in the test solution by a tenfold. The changes in the recorded current values ​​were observed. The results are as follows: Figure 4 As shown.

[0078] from Figure 4 As can be seen from a, the channel current gradually decreases after the addition of the potassium ions to be tested into the solution, exhibiting a step-like pattern. Figure 4 The calibration curve shown in b indicates that the sensing device operates at 10... -5 ~10 -1 M(R 2The results showed good linear response correlation within the concentration range of 0.9773. The trend presented by these results is consistent with the operating principle of ion sensing devices based on organic electrochemical transistors, proving the feasibility of using printed ion sensing devices for ion detection.

Claims

1. A method for constructing an organic electrochemical transistor ion sensing device based on printing technology, characterized in that, Includes the following steps: Step 1) First, the organic electrochemical transistor is fabricated: Step 1.1) Take the PI film as the flexible substrate of the organic electrochemical transistor, and sonicate the substrate in deionized water and isopropanol for 10-30 min respectively, dry it, and then perform plasma treatment on the dried substrate for 4-6 min to obtain the treated substrate. Step 1.2) Use a screen printing stencil to create two electrode layers on the substrate; Step 1.3) Except for the carbon contact points and sensing channel area, the two electrode layers are coated with insulating ink and then cured with ultraviolet light to obtain an organic electrochemical transistor. The sensing channel region is the area in the electrode layer where the source electrode, the channel layer, and the drain electrode overlap. Step 2) Then, the organic electrochemical transistor channel is modified with a polyelectrolyte layer to obtain a polyelectrolyte layer; Step 3) Finally, the ion-selective membrane of the organic electrochemical transistor channel with polyelectrolyte layer is modified to obtain the final organic electrochemical transistor ion sensing device.

2. The method for constructing an organic electrochemical transistor ion sensing device based on printing technology according to claim 1, characterized in that: Step 1.2) specifically refers to: Step 1.2.1) First, carbon paste is coated onto the first screen printing stencil. Then, the first screen printing stencil is placed on the substrate, and the first electrode layer is printed on the substrate surface by a scraping method. The first electrode layer mainly consists of the source electrode and the gate electrode of the organic electrochemical transistor. Next, conductive silver paste is used to coat the areas of the source electrode and the gate electrode of the first electrode layer, except for the carbon contact points. At the same time, Ag / AgCl paste is coated on the carbon contact points of the gate electrode of the first electrode layer to obtain a substrate coated with conductive silver paste and Ag / AgCl paste. Step 1.2.2) The substrate prepared in step 1.2.1) is subjected to plasma treatment for 4 to 6 minutes. The PEDOT:PSS mixture is drop-coated onto the preset channel region and annealed at 100℃ to 120℃ for 1 to 2 hours in an inert environment to obtain the channel layer. Step 1.2.3) Place the second screen printing stencil on the substrate obtained in step 1.2.2), and coat the carbon paste on the surface of the substrate by scraping to obtain the second electrode layer. The second electrode layer is mainly composed of drain electrodes, and the carbon contact point of the drain electrode is located above the carbon contact point of the source electrode. Then, the area on the second electrode layer other than the carbon contact point is coated with conductive silver paste.

3. The method for constructing an organic electrochemical transistor ion sensing device based on printing technology according to claim 1, characterized in that: Step 2) specifically refers to: Step 2.1) First, add DBSA, GOPS and HCl to the PSSNa aqueous solution, mix and stir until homogeneous to obtain a PSSNa mixed solution; Step 2.2) Then, using a pipette, 0.3 to 0.6 μL of PSSNa mixed solution is added to the sensing channel region of the organic electrochemical transistor obtained in step 1), and heated at 120°C to 140°C for 1 to 2 hours to perform polyelectrolyte crosslinking, so that a polyelectrolyte layer is generated on the surface of the sensing channel region of the organic electrochemical transistor. Step 2.3) Subsequently, the sensing channel region of the organic electrochemical transistor is immersed in NaCl solution for 10–14 h to remove excess PSSNa mixed solution, and then Na is stored in the polyelectrolyte layer. + ; Step 2.4) Wash off the excess NaCl solution with deionized water, and then dry the organic electrochemical transistor at room temperature to obtain an organic electrochemical transistor with a polyelectrolyte layer.

4. The method for constructing an organic electrochemical transistor ion sensing device based on printing technology according to claim 3, characterized in that: Step 3) specifically refers to: Step 3.1) Add 150 mg of solute to 1.0 mL of THF solvent to prepare a potassium ion selective membrane solution; Step 3.2) Add 0.8–1.2 μL of potassium ion-selective membrane solution to the sensing channel region of the organic electrochemical transistor obtained after drying in Step 2.4) and dry at room temperature. Repeat the addition of potassium ion-selective membrane solution and drying three times to obtain an ion-selective membrane. Step 3.3) Apply adhesive to the edge area of ​​the ion-selective membrane and cure at room temperature for more than 1 hour to complete the sealing of the organic electrochemical transistor; Step 3.4) Immerse the sealed sensing channel region of the organic electrochemical transistor in KCl solution for 10-14 hours to complete the activation, and finally obtain the organic electrochemical transistor ion sensing device.

5. The method for constructing an organic electrochemical transistor ion sensing device based on printing technology according to claim 4, characterized in that: The solute in step 3.1) is a mixture of potassium ion carrier, KTFPB, NPOE and PVC.

6. The method for constructing an organic electrochemical transistor ion sensing device based on printing technology according to claim 5, characterized in that: The mass percentages of the potassium ion carrier, KTFPB, NPOE, and PVC are 2.5 wt%, 0.5 wt%, 60.5 wt%, and 36.5 wt%, respectively.

7. The method for constructing an organic electrochemical transistor ion sensing device based on printing technology according to claim 5, characterized in that: The potassium ion carrier is at least one of the following: valhalamicin, 4-tert-butyl-2,2,14,14-tetraethyl-2a,14a,dioxo-bridged calix[4] aryl-tetraacetic acid tetratert-butyl ester, bis[(benzo-15-crown-5)-4′-methyl] heptacyanate, and 2-dodecyl-2-methyl-1,3-propadiylbis[N-[5′-nitro(benzo-15-crown-5)-4′-yl]carbamate].

8. The method for constructing an organic electrochemical transistor ion sensing device based on printing technology according to claim 2, characterized in that: The aperture size of both the first and second screen printing stencils is 380-420 mesh.

9. The method for constructing an organic electrochemical transistor ion sensing device based on printing technology according to claim 3, characterized in that: In step 2.1), the volume ratio of PSSNa to DBSA is 4000:1 to 4500:1, the volume ratio of GOPS to DBSA is 4:1 to 5:1, and the volume ratio of HCl to DBSA is 4:1 to 5:1.

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