A furan fused derivative material and its application in barium ion detection

Abstract

The application belongs to the technical field of ion detection, and particularly relates to a furan fused derivative material and application thereof in barium ion detection. In order to solve the problems of the prior art, such as complicated and complex detection, high cost, poor detection sensitivity, and unsuitability for real-time analysis, etc. in the detection of barium ions, the application provides a furan fused derivative material. The furan fused derivative material is used as an active layer of an OECT, a designed and synthesized azacrown-6 crown ether material is modified above the active layer, selectivity is provided by the azacrown ether, a full-plane barium ion sensor is prepared, and the purpose of real-time detection of barium ion concentration with rapidity, accuracy and high sensitivity can be achieved. The detection limit is as low as 10nM, which is superior to most of the currently reported barium ion sensors, and greatly meets the detection requirements of environmental water samples.

Description

Technical Field

[0001] This invention belongs to the field of ion detection technology, specifically relating to a furan-based fused derivative material and its application in barium ion detection. Background Technology

[0002] Barium (Ba), an alkaline earth metal, has long been present as a trace element in food and drinking water, and has wide applications in industry (electronics, ceramics, petroleum, etc.) and medicine (barium meal imaging, etc.). Elemental barium is not highly toxic, but soluble barium salts are extremely toxic, clinically manifesting primarily as cardiac damage and hypokalemia; severe cases can lead to paralysis or even death. Furthermore, barium ions are a common water pollutant; under biomagnification, they can accumulate in the human body and cause harm. Therefore, highly sensitive and selective detection of Ba in aqueous media is crucial. 2+ It is very important. However, there is not much research on Ba(II) pollution and detection at present. The commonly used detection methods mainly include inductively coupled plasma mass spectrometry, atomic absorption spectrometry, electrochemical sensing, and fluorescence sensing. These methods have disadvantages such as requiring skilled operators, being cumbersome and complex, being costly, and not suitable for real-time analysis.

[0003] Organic electrochemical transistors (OECTs), as hybrid ion-electron conductors, connect the gate and active layer via an electrolyte, enabling real-time conversion between ion and electronic signals. They are highly sensitive to changes in ion concentration within the electrolyte and possess signal amplification characteristics, making them suitable for ion detection in aqueous environments. Meanwhile, crown ethers, since their discovery, have exhibited a preference for alkali metal ions, primarily due to the complexation between them, thus they are widely used as complexing agents. Different sizes and types of crown ethers (e.g., nitrogen-containing crown ethers, sulfur-containing crown ethers, oxygen-containing crown ethers) exhibit varying ion selectivity, depending on the type and number of donor atoms, as well as the size and shape of the cavity relative to the cation. For example, studies have developed ion detection sensors based on OECT gate electrodes modified with 15-crown-5-thiophene and 18-crown-6-thiophene polymers. Through the different selective complexation effects of the two crown ethers, real-time detection of sodium and potassium ion concentrations was achieved, respectively (Wustoni S, Combe C, Ohayon D, et al. Membrane-free detection of metalcations with an organic electrochemical transistor. Advanced Functional Materials, 2019, 29: 1904403). Furthermore, aza-18-crown-6 has also been shown to have a good fluorescence response to barium ions, and it can be used for barium ion fluorescence sensing based on the photoinduced electron transfer (PET) mechanism. However, current methods for detecting barium ions still suffer from drawbacks such as insufficient specificity and selectivity, low detection limits, poor detection sensitivity, unsuitability for real-time analysis, cumbersome complexity, and high cost. Therefore, further development of fluorescence sensing devices with high specificity and accurate, high-sensitivity detection of barium ions is of great significance. Summary of the Invention

[0004] To overcome the shortcomings of the prior art, this invention provides a furan-based fused derivative material and its application in barium ion detection. By using the furan-based fused derivative material as the active layer of an OECT (Optical Electrochemical Transistor), and modifying the active layer with an aza-18-crown-6 type crown ether material, the complexation effect of the specific aza-crown ether material on barium ions is combined with an organic electrochemical transistor. Through the current response of the organic electrochemical transistor device, rapid, accurate, and highly sensitive detection of barium ion concentration is achieved. This invention aims to solve the problems of existing technologies in detecting barium ions, such as being cumbersome and complex, costly, having poor detection sensitivity, and being unsuitable for real-time analysis.

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

[0006] The first aspect of this invention provides a furan-based fused derivative, the structural formula of which is shown below:

[0007] ;

[0008] in, Selected from , , , , , , , , , , , , , , , ;

[0009] Selected from , , ;

[0010] Selected from , , , ;

[0011] R is selected from R1: R2: ,

[0012] R3: R4: ,

[0013] R5: .

[0014] Preferably, the structural formula of the furan-based fused derivative is as follows:

[0015] .

[0016] The second aspect of this invention provides the application of the furan-based fused derivatives described in the first aspect in the detection of barium ions.

[0017] A third aspect of the present invention provides a barium ion sensor based on an organic electrochemical transistor. The barium ion sensor includes a substrate, a gate electrode, a source electrode, a drain electrode, and a bilayer thin film covering a channel between the source and drain electrodes. The bilayer thin film includes an active layer made of a furan-based fused derivative as described in the first aspect and an azacrown ether selective layer prepared above the active layer. The azacrown ether has the following structural formula:

[0018] .

[0019] The detection mechanism of this invention based on the OECT sensor is as follows: the potential at the interface between the thin film and the electrolyte is changed by the complexation of the crown ether material NDI-18-C-6 and barium ions, thereby altering the effective gate voltage and channel current. The complexation of the crown ether with barium ions leads to an increase in the positive charge on the electrolyte side of the channel / electrolyte interface double layer, which in turn induces more electrons in the channel, forming a new double layer. This redistributes the overall voltage drop, ultimately increasing the effective gate voltage. At the same gate voltage, the effective gate voltage is greater with the addition of barium ions than without, i.e., Ba... 2+ Quantitative detection of ions can be achieved by relating barium ion concentration to ΔV. GS eff To achieve this through relationships, V GS eff The offset is proportional to the logarithm of the barium ion concentration.

[0020] Preferably, the detection limit of the barium ion sensor is 10 nM.

[0021] A fourth aspect of this invention provides a method for preparing the barium ion sensor based on the organic electrochemical transistor described in the third aspect, comprising the following steps:

[0022] S1. Deposit the gate electrode, source electrode and drain electrode on the substrate, and use high temperature tape to pattern the channel region to expose the channel;

[0023] S2. Using the solvent orthogonal method, first prepare a hexafluoroisopropanol solution of gBNR, and use gBNR to deposit the first active layer in the channel. Then prepare an ethanol solution of azacrown ether, and use azacrown ether to continue depositing the second ion-selective layer on top of the active layer.

[0024] S3. After removing the tape, a uniform double-layer structure film is obtained. Then, the groove prepared with PDMS is carefully attached around the channel and the gate electrode to obtain the barium ion sensor.

[0025] Preferably, the concentration of the hexafluoroisopropanol solution of gBNR is 7-13 mg / mL.

[0026] Preferably, the concentration of the ethanol solution of the azacrown ether is 4-8 mg / mL.

[0027] Preferably, both double-layer films are coated using a spin coating process, and both processes are carried out in two stages: running at 450-600 rpm for 4-7 seconds and then running at 900-1200 rpm for 25-45 seconds.

[0028] Preferably, the width of the channel between the source and drain electrodes is 38,000-40,000 μm and the length is 16-25 μm.

[0029] Preferably, the substrate is a glass substrate, the source and drain are gold source and gold drain, and the gate electrode is a silver gate electrode. Of course, the substrate includes, but is not limited to, a glass substrate, the source and drain include, but are not limited to, gold source and gold drain, and the gate electrode includes, but is not limited to, a silver gate electrode.

[0030] Compared with the prior art, the beneficial effects of the present invention are:

[0031] This invention uses the stable n-type small molecule semiconductor gBNR as the active layer of OECT (Optical Electron Device), and modifies the active layer with a designed and synthesized aza-18-crown-6 type crown ether material. The selectivity provided by the aza-crown ether is utilized to prepare a fully planar barium ion sensor, enabling rapid, accurate, and highly sensitive real-time detection of barium ion concentration, thus meeting the requirements for environmental water sample detection. Specifically:

[0032] (1) Using furan-based fused derivative materials as the active layer of OECT to prepare organic electrochemical transistor sensors, the transistors prepared with furan-based fused derivative materials as the active layer material have the advantages of high performance (high current, reaching more than 1 mA) and good stability (the current remains stable throughout the 2-hour pulse test), thus making the detection limit of the prepared sensor low. At the same time, the complexation between nitrogen crown ether materials and alkali metal ions is combined with organic electrochemical transistor devices. The complexation provides good ion selectivity, and the amplification characteristics of organic electrochemical transistors provide excellent sensitivity and detection limit. It can achieve real-time and accurate detection of barium ions in the water sample to be tested, with a detection limit of 10 nM, which is superior to most of the currently reported barium ion sensors in terms of detection capability.

[0033] (2) The synthesized novel aza-18-crown-6-naphthalimide small molecule NDI-18-C-6 has a special complexation effect with barium ions. Through colorimetric and absorption experiments, it was shown that barium ions can be distinguished by simple visual observation. It has the advantages of convenient operation, fast analysis speed and visualized results.

[0034] (3) NDI-18-C-6 is combined with organic electrochemical transistors and modified on the active layer of OECT using solvent orthogonal method to form a bilayer structure. Ion recognition is achieved through the complexation of nitrogen crown ether and barium ions. The potential at the interface between the thin film and the electrolyte is changed through the complexation, thereby changing the effective gate voltage and channel current.

[0035] (4) The sensor prepared by OECT does not require large instruments or equipment, is easy to manufacture, has a low operating voltage (<1V), low power consumption, good biocompatibility, can be used in an aqueous environment, has high feasibility for miniaturization and integration, and has broad application prospects in detecting heavy metal barium ions in environmental water quality and domestic water. Attached Figure Description

[0036] Figure 1 This is a flowchart illustrating the fabrication process of an OECT sensor based on gBNR.

[0037] Figure 2 The results show the selectivity test results of the gBNR-based OECT sensor.

[0038] Figure 3 Comparison of effective gate voltage changes of barium ions and other interfering ions on the OECT sensor;

[0039] Figure 4 This is a schematic diagram of the potential drop of the double layer before and after NDI-18-C-6 and barium ion complexation in an OECT device.

[0040] Figure 5 For the channel current of the OECT device as a function of Ba 2+ Real-time response graph of increased concentration;

[0041] Figure 6 The curve showing the relationship between the effective gate voltage response and the logarithm of uric acid concentration Lg[UA] (including the calibration curve), with the inset showing the calibration curve under low concentration of barium ions;

[0042] Figure 7 Steady-state transfer characteristic curves of the OECT sensor under different barium ion concentrations;

[0043] Figure 8 The graph shows the source and drain current changes of an OECT device fabricated using furan-based fused derivative material gBNR as the active layer material after 1200 cycles over 2 hours under cyclic switching voltage.

[0044] Figure 9 The color chart shows the appearance of the solution after adding various cations (2 equivalents) to NDI-18-C-6 ethanol / water solution (10-5 M);

[0045] Figure 10 The UV-Vis-NIR absorption spectra are obtained by adding various cations (2 equivalents) to NDI-18-C-6 ethanol / water solution (10-5 M). Detailed Implementation

[0046] The specific embodiments of the present invention will be further described below. It should be noted that these descriptions are for the purpose of aiding understanding the present invention, but do not constitute a limitation thereof. Furthermore, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0047] Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods, and the experimental materials used in the following embodiments are all available through conventional commercial channels.

[0048] This invention provides a furan-based fused derivative material, the structural formula of which is shown below:

[0049] ;

[0050] in, Selected from , , , , , , , , , , , , , , , ;

[0051] Selected from , , ;

[0052] Selected from , , , ;

[0053] R is selected from R1: R2: ,

[0054] R3: R4: ,

[0055] R5: .

[0056] This invention uses the aforementioned furan-based fused derivative material as the active layer of an OECT sensor, and modifies the active layer with a designed and synthesized aza-18-crown-6 type crown ether material. The selectivity provided by the aza-crown ether allows for the fabrication of a fully planar barium ion sensor, thereby achieving rapid, accurate, and highly sensitive real-time detection of barium ion concentration. Specific embodiments are provided below to further illustrate its application. It should be noted that these embodiments are preferred examples of the invention, intended for those skilled in the art to understand the invention, but the invention is not limited to these embodiments.

[0057] Example 1: Preparation of an OECT sensor based on furan-based fused derivative materials and a azeotropic crown ether-modified active layer

[0058] The furan-based fused derivative material (gBNR) used in this embodiment has the following structural formula:

[0059] ;

[0060] The azirocrown ether used is the small molecule aziro-18-crown-6-naphthaleneimide NDI-18-C-6, which has the following structural formula:

[0061] .

[0062] like Figure 1 As shown, the preparation method includes the following steps:

[0063] (1) Deposit gold source and drain electrodes (gold deposited source and drain electrodes) and silver gate electrodes on a glass substrate. The electrodes are deposited using standard photolithography / lifting process and thermal evaporation. The channel width is 39000 μm and the length is 20 μm.

[0064] (2) After the electrode is prepared, the channel area is patterned by using high temperature tape and a mask method to expose the channel.

[0065] (3) Using the solvent orthogonal method, first prepare a 10 mg / mL gBNR hexafluoroisopropanol solution, and use gBNR to spin-coat and deposit the first active layer in the channel. Then prepare a 5 mg / mL NDI-18-C-6 ethanol solution, and use NDI-18-C-6 to spin-coat and deposit the second ion-selective layer on top of the active layer (the thickness of the two films is about 80 nm (80±5 nm)). The spin-coating process of both films adopts a two-stage process of running at 500 rpm for 5 s and then running at 1000 rpm for 30 s.

[0066] (4) Since the solvent orthogonal method is used, gBNR is insoluble in ethanol. After removing the tape, a uniform double-layer structure film is obtained.

[0067] (5) Carefully attach the PDMS-prepared groove around the channel and the gate electrode to hold the electrolyte. This completes the fabrication of the sensor (gBNR-based OECT sensor).

[0068] Example 2: Detection of Ba using an OECT sensor based on gBNR 2+ Applications in

[0069] (1) Ion selectivity test of OECT sensor:

[0070] Using 0.1 M NaCl solution as the background solution, the selectivity of the sensor to different metal ions was detected by adding 0.01 mM solutions of different interfering ions (NaCl, KCl, MgCl2, LiCl, CaCl2, ZnCl2, AlCl3, PbCl2) to the sensor. Figure 2 , Figure 3 As shown. Figure 2 The results show that only by adding Ba 2+ At that time, the channel current showed a significant response, while other interfering ions showed little change. Furthermore, in Figure 3 The paper summarizes the effective gate voltage changes caused by various ions, from Figure 3 It can also be seen that barium ions have the highest response. The value of 3 mV indicates that the OECT-based barium ion sensor exhibits good selectivity. Figure 4 The change in potential drop at the double layer of the active layer before and after NDI-18-C-6 and barium ion complexation in the sensor demonstrates that the sensor can generate a signal by changing the channel current through altering the potential drop, thereby detecting Ba. 2+ The purpose.

[0071] (2) OECT sensor for Ba 2+ Sensitivity and detection range testing:

[0072] To investigate the effect of the prepared OECT sensor on Ba 2+To assess the sensitivity, a series of BaCl2 solutions with different concentrations (10 nM, 30 nM, 0.1 μM, 0.3 μM, 1 μM, 3 μM, 10 μM, 30 μM, 0.1 mM, 0.3 mM, 1 mM, 3 mM, 10 mM) were prepared using 0.1 M NaCl solution as the background solution. The prepared OECT sensor source-drain-gate electrode was connected to a semiconductor parameter analyzer (Keysight B1500A, USA), and a constant gate voltage V was set. GS (0.3 V) and source-drain voltage V DS (0.2 V), BaCl2 solution of varying concentrations was added dropwise to the electrolyte (0.1 M NaCl) using a pipette to characterize the current response of the OECT sensor. Figure 5 It can be seen that, with Ba 2+ As concentration increases, the channel current also increases continuously. It is worth noting that when exposed to low concentrations (…),… At high concentrations ( ), the barium ion sensor exhibits excellent responsiveness and minimal hysteresis. At this point, a second linear region will appear. This indicates that the barium ion sensor still has high detection sensitivity even at low concentrations.

[0073] Simultaneously, extract the device channel current change (ΔI) DS eff To explore its detection range. Figure 6 Summarizing the results under different logarithmic concentrations The logarithmic scale improves the visualization of the response at low concentrations. In the high concentration region, the OECT sensor exhibits a high slope (43.42 mV per tenfold concentration shift), with an R-value of 0.9793. The fitting formula is y = 43.42lg(x) + 166.04 (where x is the concentration of barium ions in the analyte, and y is the effective gate voltage change). The linear relationship is good, while in the low concentration region, the fitting formula is y=0.49lg(x)+4.31, and the effective gate voltage (V) is... GS eff For every tenfold concentration shift, the value is 0.49 mV, with an R-value of 0.9978, also exhibiting a good linear relationship. This demonstrates the excellent amplification capability of the OECT sensor. The sensor's detection limit reaches 10 nM, while the standard limit for drinking water is 0.7 mg / L, which is 5 × 10⁻⁶ mV. -6 Therefore, the prepared OECT device can meet the requirements of water quality detection. Its detection capability is superior to most currently reported barium ion sensors (Table 1).

[0074] Table 1. Recent reports on various Ba...2+ Comparison of Detection Methods

[0075]

[0076] Note: [1] Ardianrama A D, Pradyasti A, Woo H-C, et al. Colorimetricsensing of barium ion in water based on polyelectrolyte-induced chemicaletching of silver nanoprisms. Dyes and Pigments, 2020, 181: 108578.

[0077] [2] Zaitsev S Y, Tsarkova M S, Zaitsev I S. Polymeric compositematerials for the detection of barium ions in aqueous solutions.International Journal of Polymer Science, 2019, 2019: 4951327.

[0078] [3] Bhasin A K K, Chauhan P, Chaudhary S. A novel sulfur-incorporatednaphthoquinone as a selective “turn-on” fluorescence chemical sensor forrapid detection of Ba2+ ion in semi-aqueous medium. Sensors and Actuators B:Chemical, 2019, 294: 116-122.

[0079] [4] Basa P N, Bhowmick A, Schulz M M, et al. Site-selective iminationof an anthracenone sensor: selective fluorescence detection of barium(ii).The Journal of Organic Chemistry, 2011, 76: 7866-7871.

[0080] [5] Saluja P, Kaur N, Singh N, et al. A benzthiazole-based tripodalchemosensor for Ba2+ recognition under biological conditions. Tetrahedron Letters, 2011, 52: 6705-6708.

[0081] [6] Zhao JM, Zong QS, Chen CF. Complexation of triptycene-basedmacrotricyclic host toward (9-anthracylmethyl)benzylammonium salt: a Ba2+selective fluorescence probe. The Journal of Organic Chemistry, 2010, 75:5092-5098.

[0082] [7] Kong Chunyan, Zhao Hongrui, Hu Kaili, et al. Maleiconitrile-modified barium ion fluorescent sensor. Journal of Shandong University of Science and Technology (Natural Science Edition), 2022, 41: 68-74.

[0083] [8] Zhan Junyan, Xu Wei, Gan Chunfang, et al. Detection of Ba2+ by colorimetric method of silver nanoparticles. Journal of Guangxi Normal University (Natural Science Edition), 2019, 36: 74-78.

[0084] Furthermore, under different barium ion conditions in Part (1), the current response was measured by changing the gate voltage and source-drain voltage to obtain the transfer characteristic curve, as shown in the figure. Figure 7 As shown, the sensor current is high, exceeding 1mA. It is worth noting that regarding device operational stability, by applying cyclic switching voltages in the same test system, the source-drain current changes were measured for 1200 cycles over 2 hours. Specifically, V0 was measured when the device was turned on. GS = 0.25 V, when off Each "on" or "off" state lasts for 6 seconds. The result is as follows: Figure 8As shown, the current remained stable throughout the on / off cycle, demonstrating that the device can maintain continuous high performance and high stability during repeated cycles. It is evident that the gBNR-based transistor possesses advantages such as high performance (high current, exceeding 1mA) and good stability (current remained stable throughout the 2-hour pulse test), thus enabling the sensor fabricated from it to have a low detection limit.

[0085] Furthermore, colorimetric and absorption experiments demonstrated that the novel aza-18-crown-6-naphthaleneimide small molecule NDI-18-C-6 possesses a unique complexing effect with barium ions. Specifically, the aza-crown ether material NDI-18-C-6 was dissolved in an ethanol / water solution (1:1) to achieve a concentration of 10... -5 M. Take 2 mL of the mixed solution into a quartz cuvette, and add sodium chloride, potassium chloride, magnesium chloride, lithium chloride, calcium chloride, zinc chloride, aluminum chloride, lead chloride and barium chloride solutions in sequence, equivalent to twice the concentration of NDI-18-C-6. Record the appearance color and ultraviolet-visible-near-infrared absorption spectrum each time it is added. The spectrum is obtained under environmental conditions with ultrapure water as the background.

[0086] like Figure 9 The colorimetric results show that when the azacrown ether material NDI-18-C-6 was dissolved in an ethanol / water solution for competitive binding in a hemiaque medium, the solution turned blue without the addition of any ions. In the same control solution, 2×10⁻⁶ ions were added sequentially... -5 After applying solutions of sodium chloride, potassium chloride, magnesium chloride, lithium chloride, calcium chloride, zinc chloride, aluminum chloride, lead chloride, and barium chloride to solution M, the solution changed from blue to purple only in the presence of barium ions, exhibiting a blue shift. Solutions containing other ions, such as NDI-18-C-6, showed no significant change. This colorimetric experiment demonstrates that barium ions can be distinguished by simple visual observation, offering advantages such as ease of operation, rapid analysis, and visualized results. Figure 10 To characterize the above solution using UV-Vis-NIR absorption spectroscopy, the introduction of barium ions significantly altered the absorption of the solution phase, attributed to the complexation between the azacrown ether and barium ions in NDI-18-C-6. For pure NDI-18-C-6, the spectrum showed a maximum absorption peak at 598 nm, which is attributed to the central NDI. Absorption peak. When Ba is added... 2+ Subsequently, the peak underwent a blue shift, changing by 36 nm to 562 nm. This is due to the presence of Ba... 2+ This is due to the photoinduced electron transfer (PET) mechanism from the azeotropic crown ether to the conjugated portion of NDI during binding. Therefore, the complexation between the azeotropic crown ether material NDI-18-C-6 and barium ions enables the OECT device to have specificity for barium ion detection.

[0087] In summary, this invention uses furan-based fused derivative materials as the active layer of an OECT (Organic Electrochemical Transistor), modifies the active layer with azira-18-crown-6 crown ether materials, and combines the complexation effect of specific azira-crown ether materials on barium ions with an organic electrochemical transistor. Through the current response of the organic electrochemical transistor device, it achieves rapid, accurate, and highly sensitive detection of barium ion concentration, with a detection limit as low as 10 nM. This is superior to most reported barium ion sensors, greatly meeting the detection requirements of environmental water samples and showing significant application potential.

[0088] The embodiments of the present invention have been described in detail above, but the present invention is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and these variations still fall within the protection scope of the present invention.

Claims

1. A furan-based fused derivative, characterized in that, The structural formula of the furan-based fused derivative is shown below: 。 2. The application of the furan-based fused derivatives according to claim 1 in the detection of barium ions.

3. A barium ion sensor based on an organic electrochemical transistor, characterized in that, The barium ion sensor includes a substrate, a gate electrode, a source electrode, a drain electrode, and a bilayer thin film covering a channel between the source and drain electrodes. The bilayer thin film includes an active layer made of the furan-based fused derivative of claim 1 and an azacrown ether selective layer prepared above the active layer. The azacrown ether has the following structural formula: 。 4. The method for preparing the barium ion sensor based on organic electrochemical transistors as described in claim 3, characterized in that, Includes the following steps: S1. Deposit the gate electrode, source electrode and drain electrode on the substrate, and use high temperature tape to pattern the channel region to expose the channel; S2. Using the solvent orthogonal method, first prepare a hexafluoroisopropanol solution of the furan fused derivative as described in claim 1, and deposit a first active layer in the channel using the furan fused derivative as described in claim 1. Then prepare an ethanol solution of azacrown ether, and continue to deposit a second ion-selective layer on top of the active layer using azacrown ether. S3. After removing the tape, a uniform double-layer structure film is obtained. Then, the groove prepared with PDMS is carefully attached around the channel and the gate electrode to obtain the barium ion sensor.

5. The method for preparing a barium ion sensor based on an organic electrochemical transistor according to claim 4, characterized in that, The concentration of the hexafluoroisopropanol solution of the furan fused derivative is 7-13 mg / mL.

6. The method for preparing a barium ion sensor based on an organic electrochemical transistor according to claim 4, characterized in that, The concentration of the ethanol solution of the azacrown ether is 4-8 mg / mL.

7. The method for preparing a barium ion sensor based on an organic electrochemical transistor according to claim 4, characterized in that, Both double-layer films were produced using a spin coating process, which involved two stages: running at 450-600 rpm for 4-7 seconds and then at 900-1200 rpm for 25-45 seconds.

8. The method for preparing a barium ion sensor based on an organic electrochemical transistor according to claim 4, characterized in that, The width of the channel between the drain electrodes is 38,000-40,000 μm, and the length is 16-25 μm.

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