High-precision low-cost flexible electrochemical detection chip and processing method thereof

Abstract

The invention belongs to the field of micro-fluidic chip processing and electrochemical detection, and discloses a high-precision low-cost flexible electrochemical detection chip processing method. The high-precision and low-cost electrochemical detection chip comprises a PET substrate layer, an ITO electrode layer and an Ag / AgCl reference electrode layer, an ITO film is coated with photosensitive blue oil and exposed to form an electrode pattern, a redundant ITO plating layer is etched after development, photoresist is removed, and a three-electrode chip is obtained. And depositing AgCl on the reference electrode by adopting electrochemical deposition. The electrochemical chip can be realized without expensive consumables and precision processing equipment, the conductivity of the electrochemical chip is far better than that of a traditional silk-screen printing electrochemical chip, the electrochemical chip is more stable during electrode modification, and batch processing of the electrochemical chip with the minimum size of 200 microns can be realized by adopting the processing method. After being modified, the electrochemical chip can be applied to the field of detection of heavy metal ions, radioactive ions and various marine pollutants in a marine environment.

Description

Technical Field

[0001] This invention relates to the fields of microfluidic chip fabrication and electrochemical detection. Specifically, it provides a high-precision, low-cost flexible electrochemical detection chip and its fabrication method. Background Technology

[0002] Electrochemical detection chips, due to their high sensitivity and rapid response, are widely used in environmental monitoring, biomedicine, and marine pollutant detection. In recent years, they have shown particular value and demand in the detection of heavy metal ions and radioactive substances. Currently, mainstream technologies such as screen printing and stencil printing, while having lower costs, suffer from poor electrode conductivity, insufficient modification stability, and limited processing precision (typically >500μm), making miniaturization and multi-module integration difficult. While high-precision photolithography can reduce feature size, it relies on expensive equipment such as cleanroom environments, photoresists, and UV exposure machines, leading to a significant increase in processing costs and hindering large-scale production.

[0003] Current technologies generally face the challenge of balancing accuracy and cost, which hinders the widespread application of electrochemical chips in complex scenarios. Therefore, developing an electrochemical chip fabrication method that combines high precision, low cost, and mass production potential has become a critical issue that urgently needs to be addressed in this field. Summary of the Invention

[0004] In response to the aforementioned technical problems, this invention provides a high-precision, low-cost flexible electrochemical detection chip and its processing method to overcome the limitations in processing accuracy and integration of current electrochemical detection chips, while effectively reducing chip costs.

[0005] The technical means employed in this invention are as follows: This invention discloses a method for fabricating a high-precision, low-cost electrochemical detection chip. The ITO electrode layer is obtained by wet etching on an ITO thin film substrate, and the AgCl reference electrode layer is achieved by electrochemical deposition and chlorination.

[0006] Furthermore, the high-precision, low-cost chip processing method disclosed in this invention employs a photolithography-like method, using photosensitive ink instead of photoresist and a UV curing lamp instead of a photolithography machine. This eliminates the need for expensive photoresist and photolithography machines, allowing processing to be completed in a conventional laboratory.

[0007] Includes the following steps: S1. Photosensitive ink coating: Mix commercially available photosensitive ink and thinner evenly, and then brush it evenly onto the surface of the ITO film substrate. S2, Pre-baking: Place the ITO film coated with photosensitive ink on a heating plate and heat it for a period of time to solidify the photosensitive ink on the surface of the ITO film. S3, Exposure: Cover the ITO film coated with photosensitive ink with an electrochemical chip mask structure, and place it under a UV LED curing lamp for a period of time before peeling off the mask; S4. Development: Prepare a Na2CO3 solution with a mass fraction of 0.9%~1.1% as the developing solution, place the exposed ITO film in the developing solution, and form a light blocking layer in the shape of an electrochemical chip electrode on the ITO film. S5. Wet etching: Prepare ITO etching solution, place the developed ITO film in the ITO etching solution, heat in a water bath at 65~75℃ for 8~11 minutes to etch away the ITO coating outside the light blocking layer of the ITO film. S6. Resin removal: Prepare a resist removal solution with a mass fraction of 4%~5%, immerse the etched ITO film in the resist removal solution for 5~8 minutes to remove the light blocking layer and obtain an ITO electrochemical chip with electrode shape. S7. Electrochemical deposition and chlorination: A silver compound solution is dropped onto an ITO electrochemical chip. Using a constant potential scanning method, Ag elemental is deposited on the reference electrode for 200-500 s. After rinsing with deionized water, a chloride solution with a concentration of 0.05-0.15 M is added again. The constant potential scanning method is continued, maintaining the deposition voltage at 0.35-0.45 V. The Ag elemental is chlorinated for 250-350 s to obtain an Ag / AgCl electrode.

[0008] Furthermore, the photosensitive ink and diluent are mixed evenly at a volume ratio of (2.5~3.5):1.

[0009] Furthermore, photosensitive inks include photosensitive blue ink.

[0010] Furthermore, during the pre-baking process, the material is heated on a heating plate at 90℃~100℃ for 5~10 minutes.

[0011] Furthermore, during the exposure process, the sample is placed under a UV LED lamp for 25-30 seconds.

[0012] Furthermore, during the development process, the immersion and development time is 3-5 minutes.

[0013] Furthermore, in wet etching, according to V 浓盐酸 V 浓硝酸 V 水 The ITO etching solution was prepared in a ratio of (45~55): (2~4): (45~55).

[0014] Further, the electrochemical deposition and chlorination are as follows: an AgNO3 solution with a concentration of 3mM to 10mM is dropped onto the ITO electrochemical chip. Using a constant potential scanning method, Ag elemental is deposited on the reference electrode for 280 to 320 s at a deposition voltage range of -0.3 to -0.5V. After rinsing with deionized water for 5 to 10 s, a KCl solution with a concentration of 0.05 to 0.15M is added again. The constant potential scanning method is continued, maintaining the deposition voltage at 0.4V, and scanning for 300 s to chlorinate the Ag elemental to obtain an Ag / AgCl electrode.

[0015] Furthermore, the photosensitive blue oil, diluent, developer, and resist remover used in chip processing are all common consumables in chemical laboratories, and the processing cost is far lower than that of traditional cleanroom chip microfabrication processes.

[0016] Furthermore, the electrochemical chips processed using this method can achieve precise fabrication of chip structures with a minimum size of 200μm, and can be mass-produced.

[0017] This invention also claims protection for a high-precision, low-cost flexible electrochemical detection chip prepared based on the above-described preparation method, comprising a PET substrate layer, an ITO electrode layer, and an AgCl reference electrode modification layer.

[0018] Compared with the prior art, the present invention has the following advantages: 1) The chip processing method disclosed in this invention adopts a photolithography-like process with wet etching, which can achieve high-precision chip processing of 200μm. It can be processed with photosensitive blue oil and ultraviolet curing lamp, without the need for photoresist and expensive equipment.

[0019] 2) In the chip processing method disclosed in this invention, ITO thin film is used as chip substrate. ITO thin film has high conductivity and corrosion resistance, and is suitable for electrochemical deposition and complex environment detection.

[0020] 3) The chip processing method disclosed in this invention can complete high-precision chip processing using reagents available in conventional chemical laboratories, and has the potential for mass production.

[0021] 4) The electrochemical detection chip and chip fabrication method disclosed in this invention are similar to microelectronics fabrication processes and have strong integration potential. They can be integrated with other circuit systems or optical detection systems to form multimodal sensors. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of a high-precision, low-cost electrochemical detection chip structure according to the present invention.

[0024] Figure 2 This is a photograph of an electrochemical chip fabricated using the processing method proposed in this invention, attached to the surface of a human body.

[0025] Figure 3 Comparison of CV scans of electrochemical chips fabricated using the processing method proposed in this invention and screen-printed electrochemical chips in a 1mM K3Fe(CN)6 / K4Fe(CN)6 standard solution system.

[0026] Figure 4 This is a CV scan comparison of the electrochemical chip fabricated in this invention in a 1mM K3Fe(CN)6 / K4Fe(CN)6 standard solution system.

[0027] Figure 5 The chip fabricated using the processing method proposed in this invention is used for detecting heavy metal ions (Pb). 2+ A schematic diagram of the concentration gradient curve.

[0028] Figure 6 The gradient curve of uranyl ion detection on the chip processed by the processing method proposed in this invention.

[0029] Figure 7 The chip fabricated using the processing method proposed in this invention is used to detect the concentration gradient of uric acid. Detailed Implementation

[0030] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0031] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0033] like Figure 1 , Figure 2 As shown, this invention presents a high-precision, low-cost flexible electrochemical detection chip. The electrochemical chip includes a PET substrate layer, an ITO electrode layer, and an AgCl reference electrode modification layer. The ITO electrode layer is fabricated on an ITO thin film substrate using a photolithography-like process and wet etching. The AgCl reference electrode layer is achieved through electrochemical deposition and chlorination.

[0034] This invention also discloses a method for fabricating the above-mentioned high-precision, low-cost electrochemical detection chip, comprising the following steps: S1. Photosensitive blue oil coating. After mixing the photosensitive blue oil and diluent at a volume ratio of (2.5~3.5):1, apply the mixture evenly to the surface of the ITO film substrate with a brush.

[0035] S2. Pre-baking. Place the ITO film coated with photosensitive blue oil on a heating plate at 90℃~100℃ and heat for 5~10 minutes until the photosensitive blue oil on the surface of the ITO film solidifies.

[0036] S3. Exposure. Cover the ITO film coated with photosensitive blue oil with an electrochemical chip mask structure, and irradiate it under a UV LED lamp for 25-30 seconds before peeling off the mask.

[0037] S4. Development. Prepare a sodium carbonate solution with a mass fraction of 0.9%~1.1% as the developing solution, place the exposed ITO film in the developing solution, and immerse it for 3~5 minutes to form a light blocking layer in the shape of an electrochemical chip electrode on the ITO film.

[0038] S5, Wet etching. According to V... 浓盐酸 V 浓硝酸 V 水 =(45~55):(2~4):(45~55) Prepare ITO etching solution, place the developed ITO film in the ITO etching solution, heat in a water bath at 65~75℃ for 8~11 minutes to etch away the ITO coating outside the light blocking layer of the ITO film.

[0039] S6. Resin Removal. Prepare a 4%~5% sodium hydroxide solution as the resist remover. Immerse the etched ITO film in the resist remover for 5~8 minutes to remove the light blocking layer and obtain an ITO electrochemical chip with electrode shape.

[0040] S7. Electrochemical Deposition and Chlorination: A silver compound solution is dropped onto an ITO electrochemical chip. Using a constant potential scanning method, Ag elemental is deposited on the reference electrode for 280-320 s. After rinsing with deionized water for 5-10 s, a 0.05-0.15 M KCl solution is added again. The constant potential scanning method is continued, maintaining the deposition voltage at 0.35-0.45 V. The Ag elemental is chlorinated for 250-350 s to obtain an Ag / AgCl electrode.

[0041] Furthermore, the photosensitive blue oil and diluent, the developer, and the resist remover used for chip processing are all common consumables in chemical laboratories, and the processing cost is far lower than that of traditional cleanroom chip microfabrication processes.

[0042] Furthermore, the electrochemical chips processed using this method can achieve precise fabrication of chip structures with a minimum size of 200μm, and can be mass-produced.

[0043] Example 1 This embodiment discloses a high-precision, low-cost electrochemical detection chip fabrication method, including the following steps: S1: Photosensitive ink coating Mix the photosensitive blue oil and the thinner at a volume ratio of 3:1 to ensure uniform mixing; use a nylon brush to apply the coating twice at a uniform speed along the length of the ITO film substrate; after brushing, place the film horizontally on a clean glass slide to avoid coating drips.

[0044] S2: Pre-baking Transfer the ITO film coated with photosensitive blue oil to a heating plate, set the heating temperature to 95℃, and the heating time to 5 minutes; observe the coating status every 1 minute during the heating process to ensure that the coating changes from a viscous state to a transparent solid without bubbles or wrinkles.

[0045] S3: Exposure The electrochemical chip mask is tightly covered on the surface of the pre-baked ITO film to ensure that the mask does not shift. It is then placed under a UV LED curing lamp, 10 cm away from the film surface, for 28 seconds. After exposure, the mask is slowly peeled off along the edge of the film to avoid damaging the coating.

[0046] S4: Development Prepare a 1.0% Na2CO3 solution as the developer and pour it into a 500mL beaker. Immerse the exposed ITO film completely in the developer for 4 minutes. During the development process, gently lift the film with tweezers every minute and observe the electrode pattern under a microscope. When there are no blurry edges on the electrode and the coating in the non-electrode areas is completely dissolved, remove the film immediately.

[0047] S5: Wet etching Press V 浓盐酸 V 浓硝酸 V 水 Prepare an ITO etching solution in a ratio of 50:3:47, pour it into a container of a constant temperature water bath, set the water bath temperature to 70℃, and keep it at that temperature for 10 minutes. Vertically place the developed ITO film into the etching solution, ensuring that the film is completely immersed, and etch for 10 minutes.

[0048] S6: Remove adhesive A 4.5% NaOH solution was prepared as the resist remover, and the etched ITO film was immersed in it for 6 minutes. After the resist remover was removed, the film was first ultrasonically cleaned with deionized water, then soaked in anhydrous ethanol for 2 minutes, and finally dried with a nitrogen gun along the surface of the film at a uniform speed to obtain an ITO chip with a three-electrode pattern.

[0049] S7: Electrochemical deposition and chlorination 80 μL of 5 mM AgNO3 solution was pipetted and added to the reference electrode region of the ITO chip. The chip was placed in the three-electrode system of the electrochemical workstation, and Ag was deposited on the reference electrode surface using a constant potential scanning mode with a deposition voltage of -0.4 V and a deposition time of 300 s. After deposition, the electrode surface was rinsed with deionized water at a flow rate of 5 mL / min for 8 s and dried with nitrogen. Then, 80 μL of 0.1 M KCl solution was pipetted and added to the reference electrode region, with a deposition voltage of 0.4 V and a scan time of 300 s, to chlorinate the Ag to Ag / AgCl, thus completing the modification of the reference electrode.

[0050] Example 2 This embodiment discloses a high-precision, low-cost electrochemical detection chip fabrication method, including the following steps: S1: Photosensitive ink coating Mix the photosensitive blue oil and the thinner at a volume ratio of 2.5:1 to ensure uniform mixing; brush the coating once along the length of the ITO film to control the coating thickness to 5μm.

[0051] S2: Pre-baking The heating plate is set to 90℃. The ITO film coated with photosensitive blue oil is transferred to the heating plate, and the heating temperature is 95℃ for 6 minutes.

[0052] S3: Exposure The electrochemical chip mask was tightly covered on the surface of the pre-baked ITO film to ensure that the mask did not shift; it was then placed under a UV LED curing lamp for 25 seconds.

[0053] S4: Development Prepare a 1.1% Na2CO3 solution (500 mL in total). Completely immerse the exposed ITO film in the developer for 3 minutes. After development, the coating in the non-electrode areas is completely dissolved, and the electrode pattern is clearly visible.

[0054] S5: Wet etching Press V 浓盐酸 V 浓硝酸 V 水 The etching solution was prepared using a ratio of 45:2:53. The temperature of the constant-temperature water bath was set to 65℃. The developed ITO film was vertically placed into the etching solution to ensure that the film was completely submerged. The etching time was 9 minutes.

[0055] S6: Remove adhesive Prepare a 4.0% NaOH solution and immerse the etched ITO film for 5 minutes. After removing the adhesive, clean it with deionized water using ultrasound, immerse it in anhydrous ethanol for 1 minute, and then dry it in batches with a nitrogen gun.

[0056] S7: Electrochemical deposition and chlorination Batch modification of reference electrodes: 60 μL of 3 mM AgNO3 solution is added to each chip, and deposition is carried out at a constant potential of -0.3 V for 280 s; after rinsing with deionized water for 5 s, 60 μL of 0.05 M KCl solution is added, and scanning is carried out at a constant potential of 0.35 V for 250 s; the chip modification is completed through a multi-channel electrochemical workstation, shortening the processing cycle.

[0057] This solution is particularly suitable for batch process optimization, enabling low-cost large-scale production. It can process 20 pieces at a time in a single batch. Although its performance indicators are slightly lower than the midpoint solution, it fully meets the accuracy requirements for rapid detection of industrial wastewater.

[0058] Example 3 This embodiment discloses a high-precision, low-cost electrochemical detection chip fabrication method, including the following steps: S1: Photosensitive ink coating Mix the photosensitive blue oil and thinner at a volume ratio of 3.5:1, and stir magnetically to ensure uniform mixing; use a soft nylon brush to brush the ITO film three times along its length, controlling the coating thickness to 8μm; after brushing, place the film horizontally for 30 minutes to allow the coating to level naturally.

[0059] S2: Pre-baking Set the heating plate to 100℃, place the film in the center of the heating plate, and heat for 10 minutes.

[0060] S3: Exposure The electrochemical chip mask is tightly covered on the surface of the pre-baked ITO film to ensure that there is no gap between the mask and the film; the UV LED curing lamp is irradiated for 30 seconds, with the lamp 10cm away from the film surface to ensure that the coating is fully cured.

[0061] S4: Development Prepare a 0.9% (w / w) Na₂CO₃ solution and develop it for 5 minutes.

[0062] S5: Wet etching Press V 浓盐酸 V 浓硝酸 V 水 The etching solution was prepared using a ratio of 55:4:41. The temperature of the constant temperature water bath was set to 75℃, and the etching time was 8 minutes.

[0063] S6: Remove adhesive Prepare a 5.0% NaOH solution and soak for 8 minutes. After removing the adhesive, clean the solution with deionized water and then with anhydrous ethanol, followed by slow drying with a nitrogen gun.

[0064] S7: Electrochemical deposition and chlorination Add 100 μL of 10 mM AgNO3 solution to cover the reference electrode and the surrounding 1 mm area, and deposit at a constant potential of -0.5 V for 320 s. After rinsing with deionized water for 10 s, add 100 μL of 0.15 M KCl solution, and scan at a constant potential of 0.45 V for 350 s to complete the deposition.

[0065] Example 4 This invention discloses a comparison of the cyclic voltammetry (CV) performance of the high-precision, low-cost electrochemical detection chip and the screen-printed electrochemical chip in a 1 mL K3Fe(CN)6 / K4Fe(CN)6 standard solution system. Figure 3 As shown, the electrochemical behavior of the chip at different scan rates is fitted and analyzed. The embodiment verifies the conductivity advantage and process stability of the chip by comparing electrode response characteristics and kinetic parameters. Specific implementation details are as follows: Detection Procedure: First, the high-precision ITO electrochemical chip (processed according to the method described in Example 1) and the conventional screen-printed carbon electrode chip (commercially available model SUNJEEN-C300) were prepared respectively. Both types of chips were sequentially ultrasonically cleaned with ethanol and deionized water for 3 minutes, dried with nitrogen, and then used as the detection platform. A 1 mL K3Fe(CN)6 / K4Fe(CN)6 standard solution (containing 0.1 MkCl as a supporting electrolyte) was prepared, and the pH of the solution was adjusted to 7.0 ± 0.1.

[0066] During the detection process, CV scanning was performed using an electrochemical workstation: a potential scan range of -0.6V to 0.6V (relative to the Ag / AgCl reference electrode) was applied to the working electrodes of the two chips, with a scan rate of 50mV / s and a resting time of 5s, and the cyclic voltammetry curves were recorded.

[0067] Scan rate fitting experiment: For the ITO electrochemical chip, scan rates of 20mV / s, 40mV / s, 60mV / s, 80mV / s, 120mV / s, 140mV / s, 160mV / s, 180mV / s, and 200mV / s were set respectively, while other parameters remained unchanged, and CV curves were collected at different rates.

[0068] CV performance comparison: At the same scan rate, the oxidation peak current (Ipa-Ipa) and reduction peak current (Ipc-Ipc) of the ITO electrochemical chip are significantly higher than those of the traditional screen-printed electrode, with the peak current intensity increasing by approximately 1.5 to 2 times. The peak potential difference (ΔEp) of the ITO chip is close to the theoretical value of the reversible system (59mV), while the ΔEp of the traditional electrode deviates significantly from the ideal range (>100mV), indicating that the ITO electrode has superior electron transport efficiency and reaction reversibility.

[0069] Scan rate fitting analysis: The oxidation peak current of the ITO chip shows a high linear correlation with the square root of the scan rate (correlation coefficient R). 2 The peak current (>0.995) conforms to the diffusion-controlled reaction kinetics model. At different scan rates, the linear slope of the peak current relative to v1 / 2v1 / 2 remains stable, indicating that the electrode surface has not undergone passivation and that the reaction kinetics are highly consistent, making it suitable for detection requirements across a wide range of scan rates.

[0070] Technical advantages: In this embodiment, the high-precision ITO electrochemical chip, through a photolithography-like process, achieves a micron-scale electrode structure and high conductivity on the ITO substrate, significantly improving electron transport efficiency and reaction reversibility. For example... Figure 3As shown, the cyclic voltammetry (CV) curves of the ITO electrochemical chip in a 1 mL K3Fe(CN)6 / K4Fe(CN)6 standard solution system are closer to those of an ideal reversible system compared to those of a traditional screen-printed electrode. Furthermore, the chip exhibits excellent linear fitting characteristics at different scan rates, validating the potential of the fabrication method in electrode consistency and mass production. These results provide reliable theoretical and experimental basis for the application of electrochemical detection chips in complex analytical systems, such as... Figure 4 The image shows a CV scan comparison of the electrochemical chip fabricated according to this invention in a 1mM K3Fe(CN)6 / K4Fe(CN)6 standard solution system. The cyclic voltammetric response characteristics of the chip demonstrate excellent electron transport efficiency and reaction reversibility. Its peak potential difference is close to the theoretical reversible system value, far superior to the performance of traditional electrodes. Simultaneously, the oxidation peak current exhibits a high linear correlation with the square root of the scan rate, consistent with the diffusion-controlled reaction kinetic model, and maintains a stable linear relationship at different scan rates. This confirms that no passivation occurs on the electrode surface and the reaction kinetics are highly consistent, enabling it to meet detection requirements across a wide range of scan rates. These performance advantages are attributed to the micron-scale electrode structure achieved through a photolithography-like process and the high conductivity of the ITO substrate, which significantly improves the electron transport efficiency and process stability at the electrode interface, while also verifying the technical potential of this method in mass production.

[0071] Example 4 This invention discloses a high-precision, low-cost electrochemical detection chip for detecting heavy metal ions Pb. 2+ Applications to verify the effectiveness of ITO chips for trace Pb 2+ Its detection sensitivity and quantitative capabilities are suitable for marine environmental monitoring. The process includes the following steps: This invention discloses the high-precision, low-cost electrochemical detection chip for heavy metal ion Pb. 2+ Specific applications in detection. The detection method is based on anodic stripping voltammetry (ASV), combined with the high conductivity and stability of the ITO working electrode, counter electrode, and Ag / AgCl reference electrode of the electrochemical chip, to achieve the detection of Pb²⁺. + High-sensitivity quantitative analysis. The specific implementation method is as follows: Detection process: First, prepare a solution containing Pb. 2+ A series of standard solutions were prepared, with concentration gradients from 0.1 μM to 10 μM, using 0.1 M potassium nitrate (KNO3) as the supporting electrolyte. The pH of the solution was adjusted to 4.5 ± 0.1 using dilute nitric acid. The fabricated electrochemical chip was then ultrasonically cleaned in ethanol and deionized water for 3 min in sequence, dried with nitrogen, and used as a detection platform.

[0072] During the testing process, an electrochemical workstation (model Palmsens4) was used to control the parameters: Enrichment stage: In constant potential mode, a reduction potential of -1.2V (relative to the Ag / AgCl reference electrode) is applied to the working electrode for 120s to reduce the Pb concentration in the solution. 2+ It is reduced to metallic lead and enriched on the electrode surface; Settling stage: After enrichment, allow the system to stand for 10 seconds to ensure stability. Dissolution phase: Dissolution scanning was performed using square wave voltammetry (SWV), with a potential scan range of -1.0V to 0.2V, a scan step size of 5mV, a square wave frequency of 25Hz, and an amplitude of 50mV. The dissolution peak current was recorded, and the peak potential (approximately -0.6V) was used as the quantitative basis.

[0073] Test results: such as Figure 5 To obtain the Pb-soluble Pb-based chip for heavy metal ion detection using the processing method proposed in this invention, the method described above is used. 2+ A schematic diagram of the concentration gradient is shown, revealing the relationship between peak current and Pb. 2+ The concentration showed a linear relationship, and the linear regression equation was Ip = (0.28 ± 0.02). C + (0.05 ± 0.01)Ip = (0.28 ± 0.02) C+(0.05±0.01) (Ip is peak current / μA, CC is concentration / μM), correlation coefficient R2>0.99, linear range from 0.1μM to 10μM. Spiked recovery experiments on actual seawater samples showed recoveries of 95%–105%, with a detection limit (LOD) as low as 0.05μM (signal-to-noise ratio S / N=3). Compared to traditional screen-printed electrodes, the ITO electrochemical chip exhibits a significantly increased dissolution peak current intensity, indicating significantly enhanced conductivity and detection sensitivity.

[0074] In this embodiment, the electrochemical chip utilizes a micron-scale electrode structure (minimum 200 μm) fabricated using a photolithography-like process and the high conductivity of the ITO substrate to effectively improve the enrichment efficiency and signal response of heavy metal ions. The stability of the Ag / AgCl reference electrode further ensures the reproducibility of the detection. This method requires no complex pretreatment, has a highly efficient detection process, and is suitable for trace Pb detection in marine environments, industrial wastewater, and other scenarios. 2+ Rapid monitoring provides a feasible solution for the low-cost, high-precision application of electrochemical sensing technology.

[0075] Example 6 This invention discloses the high-precision, low-cost electrochemical detection chip for radioactive uranyl ions (UO2). 2 +Specific applications in detection. The detection method is based on square wave stripping voltammetry (SWASV), combined with the high conductivity and stability of the ITO working electrode, counter electrode, and Ag / AgCl reference electrode of the electrochemical chip, to achieve the detection of UO2. 2+ High-sensitivity quantitative analysis. The specific implementation method is as follows: Testing process: First, prepare a solution containing UO2. 2+ A series of standard solutions were prepared, with concentration gradients from 0.05 μM to 5 μM, using 0.1 M sodium acetate-acetic acid buffer solution (pH 4.0 ± 0.1) as the supporting electrolyte. The fabricated electrochemical chip was sequentially ultrasonically cleaned in ethanol and deionized water for 3 min, dried with nitrogen, and then used as a detection platform.

[0076] During the detection process, the parameters were controlled using an electrochemical workstation (model Palmsens4): In constant potential mode, an enrichment potential of -0.8V (relative to the Ag / AgCl reference electrode) was applied to the working electrode for 180s to increase the concentration of UO2 in the solution. 2+ The uranium (IV) was reduced to uranium (IV) and enriched on the electrode surface. After enrichment, the system was allowed to stand for 15 seconds to ensure stability. Subsequently, a square wave voltammetry method was used for stripping scanning, with a potential scan range of -0.6V to 0.4V, a scan step size of 4mV, a square wave frequency of 20Hz, and an amplitude of 60mV. The stripping peak current was recorded, and the peak potential (approximately -0.3V) was used as the quantitative basis.

[0077] Test results: such as Figure 6 The gradient curve of uranium ion detection on the chip processed by the method proposed in this invention, obtained by the method described above, yields the dissolution peak current and UO2. 2+ The concentration showed a linear relationship, and the linear regression equation was Ip = (0.35 ± 0.03). C+(0.02±0.005)Ip=(0.35±0.03) C+(0.02±0.005) (Ip is the peak current / μA, CC is the concentration / μM), correlation coefficient R 2 The value is >0.99, with a linear range of 0.05 μM to 5 μM. This indicates significantly enhanced conductivity and anti-interference capability.

[0078] Technical Advantages: In this embodiment, the electrochemical chip utilizes a micron-scale electrode structure (minimum 200 μm) fabricated using a photolithography-like process and the high chemical stability of the ITO substrate, effectively improving the enrichment efficiency and signal response of uranyl ions. The long-term stability of the Ag / AgCl reference electrode further ensures the reproducibility of detection in complex media. The method requires no radioactive labeling or complex pretreatment, offering a highly efficient detection process suitable for trace UO2 in scenarios such as nuclear industrial wastewater and marine environments. 2+Rapid monitoring provides a reliable solution for low-cost, high-precision electrochemical sensing of radioactive contaminants.

[0079] Example 7 This invention discloses the specific application of the high-precision, low-cost flexible electrochemical detection chip in the detection of uric acid (UA) by adhesion to curved surfaces of the human body. The detection method is based on differential pulse voltammetry (DPV), and combines the high conductivity and mechanical flexibility of the ITO working electrode, counter electrode, and Ag / AgCl reference electrode of the flexible electrochemical chip to achieve highly sensitive in-situ detection of UA. Specific implementation methods are as follows: Detection Procedure: First, a series of standard solutions containing UA were prepared with a concentration gradient from 10 μM to 200 μM, using 0.1 M phosphate buffered saline (PBS, pH 7.4 ± 0.1) as the supporting electrolyte. The fabricated flexible electrochemical chip was then ultrasonically cleaned in ethanol and deionized water for 3 min each, and dried with nitrogen to serve as the detection platform. Utilizing the flexibility of the PET substrate, the chip was attached to a surface simulating the curvature of the human body (such as a wrist joint). The sweat sample to be tested was introduced through a microfluidic channel, ensuring full contact between the electrode and the sample.

[0080] During the testing process, the parameters were controlled using an electrochemical workstation (model CHI760E): Pretreatment stage: In constant potential mode, an oxidation potential of +0.6V (relative to Ag / AgCl reference electrode) is applied to the working electrode for 30s to activate the electrode surface; Enrichment stage: Apply a reduction potential of -0.2V for 60s to promote the adsorption and enrichment of UA on the electrode surface; Detection phase: Differential pulse voltammetry (DPV) was used for scanning, with a potential scan range of -0.4V to +0.6V, a pulse amplitude of 50mV, a pulse width of 50ms, a step size of 5mV, and a resting time of 5s. The oxidation peak current was recorded, and the peak potential (approximately +0.35V) was used as the quantitative basis.

[0081] Test results: Figure 7 The concentration gradient map of uric acid detected by the chip processed by the method proposed in this invention was obtained by the method described above. It was found that the oxidation peak current and UA concentration have a linear relationship, and the linear regression equation is Ip=(0.18±0.01). C+(0.03±0.005) Ip =(0.18±0.01) C +(0.03±0.005)(Ip Ip Peak current / μA, C C (concentration / μM), correlation coefficient R 2The linear range is >0.99, with a linearity of 10 μM to 200 μM. Spiked recovery experiments on simulated sweat samples showed recoveries of 97%–103%, and a detection limit (LOD) as low as 5 μM (signal-to-noise ratio S / N = 3). Compared to traditional rigid electrodes, the flexible electrochemical chip maintains a stable peak current response even when attached to a curved surface, with signal fluctuations less than 3%, and an approximately 1.5-fold increase in detection sensitivity, demonstrating its excellent mechanical adaptability and deformation resistance. In this embodiment, the flexible electrochemical chip achieves a close fit to the curved surface of the human body through a micron-scale electrode structure (minimum 200μm) processed by a photolithography-like process and the flexibility of the PET substrate, avoiding the contact problems caused by deformation of traditional rigid electrodes. The Ag / AgCl reference electrode maintains a stable potential output even when bent, ensuring detection reproducibility. This method eliminates the need for blood samples, enabling non-invasive real-time monitoring of UA through sweat, providing a high-precision, low-cost solution for portable diagnosis of diseases such as diabetes and gout.

[0082] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for fabricating a high-precision, low-cost flexible electrochemical detection chip, characterized in that, The electrochemical chip includes a PET substrate layer (1), an ITO electrode layer (2), and an AgCl reference electrode modification layer (3). The ITO electrode layer is obtained by photolithography and wet etching on an ITO thin film substrate, and the AgCl reference electrode layer is obtained by electrochemical deposition and chlorination.

2. The processing method according to claim 1, characterized in that, Includes the following steps: S1. Photosensitive ink coating: After mixing the photosensitive ink and thinner evenly, apply the mixture evenly to the surface of the ITO film substrate with a brush. S2, Pre-baking: Place the ITO film coated with photosensitive ink on a heating plate and heat it for a period of time to solidify the photosensitive ink on the surface of the ITO film. S3, Exposure: Cover the ITO film coated with photosensitive ink with an electrochemical chip mask structure, and place it under a UV LED curing lamp for a period of time before peeling off the mask; S4. Development: Prepare a Na2CO3 solution with a mass fraction of 0.9%~1.1% as the developing solution, place the exposed ITO film in the developing solution, and form a light blocking layer in the shape of an electrochemical chip electrode on the ITO film. S5. Wet etching: Prepare ITO etching solution, place the developed ITO film in the ITO etching solution, heat in a water bath at 65~75℃ for 8~11 minutes to etch away the ITO coating outside the light blocking layer of the ITO film. S6. Resin removal: Prepare a resist removal solution with a mass fraction of 4%~5%, immerse the etched ITO film in the resist removal solution for 5~8 minutes to remove the light blocking layer and obtain an ITO electrochemical chip with electrode shape. S7. Electrochemical deposition and chlorination: A silver compound solution is dropped onto an ITO electrochemical chip. Using a constant potential scanning method, Ag elemental is deposited on the reference electrode for 200-500 s. After rinsing with deionized water, a chloride solution with a concentration of 0.05-0.15 M is added again. The constant potential scanning method is continued, maintaining the deposition voltage at 0.35-0.45 V. The Ag elemental is chlorinated for 250-350 s to obtain an Ag / AgCl electrode.

3. The electrochemical chip fabrication method according to claim 2, characterized in that, The photosensitive ink and diluent are mixed evenly at a volume ratio of (2.5~3.5):

1.

4. The electrochemical chip fabrication method according to claim 2, characterized in that, Photosensitive inks include photosensitive blue ink.

5. The electrochemical chip fabrication method according to claim 2, characterized in that, During the pre-baking process, heat on a heating plate at 90℃~100℃ for 5~10 minutes.

6. The electrochemical chip fabrication method according to claim 2, characterized in that, During the exposure process, place it under a UV LED lamp for 25-30 seconds.

7. The electrochemical chip fabrication method according to claim 2, characterized in that, During the development process, the immersion development time is 3-5 minutes.

8. The electrochemical chip fabrication method according to claim 2, characterized in that, In wet etching, according to V 浓盐酸 V 浓硝酸 V 水 The ITO etching solution was prepared in a ratio of (45~55): (2~4): (45~55).

9. The electrochemical chip fabrication method according to claim 2, characterized in that, The electrochemical deposition and chlorination process is as follows: A 3mM~10mM AgNO3 solution is dropped onto the ITO electrochemical chip. Using a constant potential scanning method, Ag elemental is deposited on the reference electrode for 280~320s at a deposition voltage range of -0.3~-0.5V. After rinsing with deionized water for 5~10s, a 0.05~0.15M KCl solution is added again. The constant potential scanning method is continued, maintaining the deposition voltage at 0.4V, and the Ag elemental is chlorinated for 300s to obtain an Ag / AgCl electrode.

10. An electrochemical chip prepared based on any one of the electrochemical chip fabrication methods of claims 1 to 9.

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