High-reliability biosensing metal electrode and preparation method thereof

Abstract

The invention relates to the field of biological detection sensors, and discloses a high-reliability biosensing metal electrode and a preparation method thereof, and the preparation method comprises the following steps: S1, depositing a nickel layer on the surface of the metal electrode; s2, depositing a gold layer on the surface of the metal electrode; s3, depositing a platinum layer on the surface of the metal electrode; in the platinum layer deposition process, a wetting agent is added into an adopted platinum plating electrolyte. The coating framework is innovatively designed, the gradient coating design on the surface of the prepared metal electrode can give consideration to the functions of electric conduction, corrosion resistance and catalysis, the nickel layer can block diffusion between the metal base material and precious metal, the interface bonding strength is improved, and failure caused by electrochemical incompatibility is avoided.

Description

Technical Field

[0001] This application relates to the field of biosensors, and mainly to a highly reliable biosensor metal electrode and its preparation method. Background Technology

[0002] As in vitro diagnostic technologies develop towards multi-indicator and miniaturization, biosensor metal electrodes need to be densely integrated in a small space and achieve precise signal transmission under low current. Therefore, developing low-cost, mass-producible, and highly reliable biometal electrodes has become crucial.

[0003] However, existing technologies face significant challenges in meeting these needs, mainly in two aspects. First, the adaptability of multi-metal electrodes is insufficient. Different detection indicators require matching with specific metals (such as Pt providing catalytic activity, Ag providing stability and low cost, etc.), but the switching cost of existing processes is high, and the interface failure between multi-metal coatings is easily caused by electrochemical incompatibility. Second, the long-term stability of metal electrodes is insufficient. Problems such as corrosion by biological fluids, protein adsorption, and enzyme activity decay cause metal electrode signal drift. For example, metal electrodes for continuous glucose monitoring (CGM) cannot meet the stable monitoring requirements for more than 14 days.

[0004] Therefore, existing technologies still need to be improved and developed. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the purpose of this application is to provide a highly reliable metal electrode for biosensing and its preparation method, aiming to solve the problems of high cost or insufficient stability of existing metal electrodes used for biosensing.

[0006] The technical solution of this application is as follows: A method for fabricating a highly reliable biosensing metal electrode, comprising the following steps: S1. Deposit a nickel layer on the surface of the metal electrode: the thickness of the nickel layer is 1-5 μm; S2. Deposit a gold layer on the surface of the metal electrode: the thickness of the gold layer is 50-250 nm; S3. Deposit a platinum layer on the surface of the metal electrode: the thickness of the platinum layer is 0.5 μm-1 μm; The platinum plating electrolyte used in the platinum deposition process contains a wetting agent.

[0007] In this application, an innovative coating architecture is designed. The gradient coating design on the surface of the metal electrode can take into account the functions of conductivity, corrosion resistance and catalysis. The nickel layer can block the diffusion between the metal substrate and the noble metal, improve the interfacial bonding strength, and avoid failure caused by electrochemical incompatibility.

[0008] The method for preparing a highly reliable biosensor metal electrode, wherein when the substrate of the metal electrode is copper, the method further includes the following steps before step S1: S0. Deposit a copper layer on the surface of the metal electrode: the thickness of the copper layer is 3-6 μm.

[0009] The copper layer serves as a transition layer, enhancing the conductivity and interfacial adhesion of the metal electrode. Pre-plating with copper can mitigate potential jumps and improve the corrosion resistance of the coating. The purpose of pre-plating with copper is to smooth the surface of the Cu substrate, ensuring excellent adhesion between the subsequent coating and the copper substrate. The method for preparing the high-reliability biosensor metal electrode includes a copper layer deposition process with a processing time of 80-150 s and a current density of 9-15 A / dm³. 2 The operating temperature range is 20-40℃, and the pH value of the copper plating electrolyte is 0.8-1.8. The formulation of the copper plating electrolyte is as follows: CuSO4·5H2O 180-220g / L, H2SO4 50-80g / L, chloride ions 30-80mg / L, leveling agent 0.1-0.5g / L; The leveling agent is one of nitrogen-containing biphenyl compounds and their quaternary ammonium salt derivatives.

[0010] The method for fabricating a high-reliability biosensor metal electrode, wherein the current density during the nickel layer deposition process is 2-8 A / dm³. 2 The processing time is 50-150 seconds, the pH value of the nickel plating electrolyte is in the working range of 3.5-5.0, and the working temperature is in the range of 45-65℃. The formulation of the nickel plating electrolyte is as follows: Nickel sulfate (NiSO4·6H2O) 200-300 g / L, nickel chloride (NiCl2·6H2O) 30-60 g / L, boric acid (H3BO3) 30-50 g / L; The method for preparing the high-reliability biosensor metal electrode, wherein the gold layer deposition process has a processing time of 5-60 s and a current density of 2-6 A / dm³. 2 The operating temperature range is 40-60℃, and the pH range of the gold plating electrolyte is 4.0-5.5. The formula for the gold plating electrolyte is as follows: Gold salt 1-5g / L, potassium citrate or sodium citrate 30-80g / L, potassium dihydrogen phosphate 10-30g / L; The gold salt is potassium gold cyanide.

[0011] The method for preparing the high-reliability biosensor metal electrode, wherein the platinum layer deposition process has a processing time of 300-1000 s and a current density of 1-2 A / dm³. 2 The operating temperature range is 80-90℃, the pH value of the platinum plating solution is 8-10, and the wetting agent is sodium dodecyl sulfate. The formulation of the platinum plating electrolyte is as follows: Platinum salt 100-300 g / L, ammonium nitrate 1000-1100 g / L, sodium nitrite 100-150 g / L, sodium dodecyl sulfate 5-200 mg / L, and the pH value is adjusted to 8-10 with ammonia.

[0012] The method for preparing the high-reliability biosensor metal electrode further includes the following steps after step S0: The metal electrode is immersed in a sulfuric acid solution with a concentration of 3-5 mol / L for 10-30 seconds.

[0013] The method for preparing the high-reliability biosensor metal electrode further includes the following steps in step S1: The desired metal electrode is formed by etching or stamping the metal substrate according to the desired structure of the metal electrode, and the surface of the metal electrode is pretreated. The metal electrode is first subjected to cathodic desorption treatment, and then electrolytic polishing treatment. The metal electrode is subjected to anodic electro-desorption treatment; The surface of the metal electrode is activated.

[0014] The method for preparing the high-reliability biosensing metal electrode, wherein the metal substrate is one of copper and nickel; The surface pretreatment is one or two of alkaline washing, acid washing, or surfactant cleaning. The cathode electro-desorption process takes 10-20 seconds and has a current density of 3-5 A / dm³. 2 The working pH range of the cathode electrolytic de-electrolyte is 10.5~13.0, and the working temperature range is 50~80℃; The formulation of the cathode electrolytic de-electrolyte is as follows: Sodium hydroxide 30~40 g / L, sodium carbonate 25~35 g / L, trisodium phosphate 30~40 g / L, sodium silicate 3~5 g / L, OP emulsifier 1~3 g / L, sodium gluconate 5~8 g / L; The electropolishing process involves a processing time of 20-50 seconds and a current density of 15-25 A / dm². 2The operating temperature range is 60~70℃, and the pH value of the electropolishing electrolyte is 2.0~2.5. The anodic electro-desorption process has a processing time of 10-20 seconds and a current density of 1-5 A / dm³. 2 The operating temperature range is 20~40℃, and the pH value of the anolyte deionization electrolyte is 1.0~2.0. The formulation of the anolyte for deionization is as follows: Phosphoric acid 100~200ml / L, sulfuric acid 50~100ml / L, nitric acid 10~30ml / L, urea 5~10g / L; The activation process specifically involves immersing the metal electrode in a sulfuric acid solution with a concentration of 3-5 mol / L for 10-30 seconds.

[0015] A highly reliable biosensing metal electrode is prepared using the method described above for preparing a highly reliable biosensing metal electrode.

[0016] Beneficial effects: The high-reliability biosensing metal electrode of this application features an innovative design of the coating architecture. The gradient coating design on the surface of the prepared metal electrode can take into account conductivity, corrosion resistance and catalytic function. The nickel layer can block the diffusion between the metal substrate and the noble metal, improve the interfacial bonding strength and avoid failure caused by electrochemical incompatibility. Attached Figure Description

[0017] Figure 1 This is a SEM image (magnification 1k) of the metal electrode prepared in Example 1 of this application.

[0018] Figure 2 This is a SEM image (magnification 50k) of the metal electrode prepared in Example 1 of this application.

[0019] Figure 3 The graph shows the performance test results of the metal electrode prepared in Example 1 of this application in a three-electrode electrolytic cell system.

[0020] Figure 4 This is a comparison of SEM images of the embodiments and comparative examples of this application. Detailed Implementation

[0021] This application provides a highly reliable metal electrode for biosensing and a method for preparing the same. To make the objectives, technical solutions, and effects of this application clearer and more explicit, the following provides a more detailed description. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0022] The method for preparing high-reliability biosensor metal electrodes provided in this application is based on existing mature electroplating processes and combined with the requirements of biosensors for metal electrodes. Through coating structure design, electroplating process optimization, and electrochemical testing, it achieves low-cost, high-consistency, and long-life biosensor metal electrode preparation.

[0023] The method for preparing the high-reliability biosensor metal electrode of this application mainly includes three parts, namely, pretreatment, electropolishing and electroplating deposition of multilayer metal. The pretreatment corresponds to step (1), the electropolishing corresponds to step (2), and the electroplating deposition of multilayer metal corresponds to (3)-(8).

[0024] Specifically, the method for preparing the high-reliability biosensor metal electrode of this application includes the following steps: (1) Pretreatment: The metal substrate is etched or stamped to form the required metal electrode according to the required metal electrode structure. The surface of the metal electrode is pretreated to achieve the effect of cleaning and activating the surface of the metal electrode.

[0025] In this step, the metal substrate is preferably one of inexpensive metals such as copper or nickel. In this application, using inexpensive metals such as copper or nickel instead of precious metals (gold, platinum) as the main body of the functional layer can significantly reduce the production cost of the metal electrodes. In the embodiments of this application, copper is selected as the metal substrate because copper is not only low in cost but also has high conductivity. Millimeter-scale electrode structures are formed through etching or stamping processes, followed by pretreatment such as degreasing and pickling to ensure the cleanliness and activation of the substrate surface.

[0026] In this step, the surface pretreatment can be one or two of alkaline washing, acid washing, or surfactant cleaning.

[0027] In the embodiments of this application, the surface pretreatment is pickling. Preferably, a sulfuric acid solution with a mass concentration of 5-10% is used to pickle the metal electrode for 10-60 seconds to remove oxides and grease from the surface of the metal electrode and enhance the adhesion of the subsequent coating.

[0028] If the metal electrode is formed by etching, a layer of black organic oil will adhere to its surface. This needs to be cleaned with a surface cleaner to remove the oil before acid washing. Any commercially available surface cleaner will suffice, and will not be elaborated upon here.

[0029] (2) Cathode electro-desorption and electropolishing: The metal electrode is first subjected to cathode electro-desorption treatment, and then electropolishing treatment is performed.

[0030] Specifically, during the cathodic electro-desorption process, the treatment time is 10-20 seconds, and the current density is 3-5 A / dm³. 2The pH range of the cathode electrolytic deionization electrolyte is 10.5~13.0, and the operating temperature range is 50~80℃. Through cathode electrolytic deionization, organic matter such as grease on the surface of the metal electrode is further removed.

[0031] Specifically, during the electropolishing process, the treatment time is 20-50 seconds, and the current density is 15-25 A / dm³. 2 The operating temperature range is 60~70℃, and the pH range of the electropolishing electrolyte is 2.0~2.5. Electropolishing treatment makes the surface of the metal electrode smooth.

[0032] Specifically, the formulation of the cathodic electrolysis electrolyte used in the cathodic electrolysis process can be as follows: Sodium hydroxide 30~40 g / L, sodium carbonate 25~35 g / L, trisodium phosphate 30~40 g / L, sodium silicate 3~5 g / L, OP emulsifier 1~3 g / L, sodium gluconate 5~8 g / L.

[0033] The formulation and operating conditions of the above-mentioned cathodic electrodesorption electrolyte can be adjusted appropriately according to actual working conditions. The advantage of using the above-mentioned cathodic electrodesorption electrolyte is that it ensures efficient degreasing of the metal electrode during the cathodic electrodesorption process, while protecting the metal electrode from damage, providing a clean and moderately active surface for subsequent electropolishing and anodic electrodesorption. In the scheme of this application, all electrolytes used can be prepared using deionized water.

[0034] Specifically, when performing electropolishing, if the metal substrate is copper, the electropolishing electrolyte used can be the phosphoric acid electrolyte used for electropolishing pure copper precision terminals, and its formula can be as follows: Phosphoric acid (mass concentration ≥85%) 600~800ml / L, sulfuric acid (mass concentration 98%) 50~150ml / L, glycerol 30ml / L, urea 8g / L.

[0035] When the metal substrate is another metal, an electropolishing electrolyte of the corresponding metal can be used.

[0036] The formulation and working conditions of the above electropolishing electrolyte can be adjusted appropriately according to actual working conditions. The advantage of using the above electropolishing electrolyte is that the use of high-concentration (≥70%) and high viscosity of phosphoric acid can slow down horizontal diffusion, promote the formation of Cu(II)-phosphate complex in the depression area, and inhibit selective corrosion.

[0037] (3) Anodic desorption: The metal electrode is subjected to anodic desorption treatment.

[0038] Specifically, during the anodic electro-desorption process, the treatment time is 10-20 seconds, and the current density is 1-5 A / dm³.2 The operating temperature range is 20~40℃, and the pH range of the anodic electrolytic electrolyte is 1.0~2.0. Through anodic electrolytic desorption, impurities, oxides, and undesirable structures are removed from the surface of the metal electrode, providing a clean and activated surface for subsequent plating, ensuring a strong and uniform bond between the plating and the metal substrate.

[0039] Specifically, the formulation of the anodic electrolytic electrolyte used in anodic electrolytic desorption treatment can be as follows: Phosphoric acid (85% concentration) 100~200ml / L, sulfuric acid (98% concentration) 50~100ml / L, nitric acid (68% concentration) 10~30ml / L, urea 5~10g / L.

[0040] The formulation and working conditions of the above anodic de-electrolyte can be adjusted appropriately according to the actual working conditions. The advantage of using the above anodic de-electrolyte is that it can remove the trace amount of dust, oxide film or localized excessively thick loose layer that may remain on the surface of the metal electrode after polishing, ensuring surface cleanliness and uniformity. (4) Activation: The surface of the metal electrode is activated.

[0041] Specifically, during the activation process, the metal electrode is immersed in a sulfuric acid solution with a concentration of about 3-5 mol / L for 10-30 seconds to remove the oxide layer on the surface.

[0042] (5) Copper plating: depositing a copper layer on the surface of a metal electrode.

[0043] In this step, the deposited copper layer is 3-6 μm thick. The copper layer serves as a transition layer, enhancing the conductivity and interfacial adhesion of the metal electrode. Simultaneously, if nickel is directly plated onto the surface of the metal electrode (taking copper as an example), the direct bonding between nickel and copper may lead to electrochemical corrosion due to the potential difference. Pre-plating copper mitigates potential jumps and improves the corrosion resistance of the coating. The purpose of pre-plating copper is to smooth the surface of the Cu substrate, ensuring excellent adhesion between the subsequent coating and the copper substrate.

[0044] When nickel is used as the substrate, pre-plating with nickel is not necessary. The key is whether the activation (pickling) step is thorough, ensuring that the oxide film on the surface of the metal substrate is completely removed and in an active state.

[0045] Specifically, in this step, the processing time is 80-150 seconds, and the current density is 9-15 A / dm³. 2The operating temperature range is 20-40℃, and the pH range of the copper plating electrolyte is 0.8-1.8 (strongly acidic range). Using these parameters ensures deposition efficiency while minimizing edge effects, resulting in a finely crystallized and strongly bonded coating. A processing time of 80-150 seconds allows for control of the coating thickness within a reasonable range of 3-6 μm, meeting dimensional accuracy requirements and preventing impurity inclusions, ultimately achieving a balance between coating quality, production efficiency, and precision.

[0046] Specifically, the formulation of the copper plating electrolyte used when depositing a copper layer on the surface can be as follows: CuSO4·5H2O 180-220g / L, H2SO4 (mass concentration of 98%) 50-80g / L, chloride ions (such as HCl) 30-80mg / L, leveling agent 0.1-0.5g / L.

[0047] The leveling agent can be a nitrogen-containing biphenyl compound or its quaternary ammonium salt derivative.

[0048] In the above formula, sufficient copper sulfate can meet the deposition requirements, sulfuric acid can enhance conductivity and inhibit hydrolysis, and trace amounts of chloride ions can refine crystals, thus ensuring the overall density and uniformity of the coating, while also being low in cost and easy to maintain.

[0049] Furthermore, after the copper plating step is completed, preferably, the following steps are also included: The metal electrode is immersed in a sulfuric acid solution with a concentration of about 3-5 mol / L for 10-30 seconds to remove the oxide layer on the surface and activate it.

[0050] (6) Nickel plating: depositing a nickel layer on the surface of a metal electrode.

[0051] In this step, the thickness of the deposited nickel layer is 1-5 μm. The nickel layer acts as a barrier layer, which can suppress atomic diffusion between the metal substrate and the functional layer.

[0052] Specifically, in this step, the current density is 2-8 A / dm³. 2 The processing time is 50-150 seconds, the pH range of the nickel plating electrolyte is 3.5-5.0 (weakly acidic range), and the operating temperature range is 45-65℃.

[0053] Specifically, the formulation of the nickel plating electrolyte used when depositing a nickel layer on the surface can be as follows: Nickel sulfate (NiSO4·6H2O) 200-300 g / L, nickel chloride (NiCl2·6H2O) 30-60 g / L, boric acid (H3BO3) 30-50 g / L.

[0054] In the above nickel plating electrolyte, nickel sulfate can provide sufficient nickel ions to match the deposition requirements, nickel chloride can enhance conductivity and activate the anode, and boric acid can stabilize the electrolyte pH and refine the crystals. Overall, it ensures the density and adhesion of the nickel layer, while also having low cost and strong process stability.

[0055] The working pH range of the nickel plating electrolyte is 3.5-5.0. It works synergistically with boric acid concentration (30-50 g / L) to inhibit nickel ion hydrolysis and ensure nickel ion deposition activity. The medium-temperature environment provided by the operating temperature enhances the nickel ion diffusion rate and promotes the adsorption effect of additives. The current density should be controlled at 2-8 A / dm³. 2 This reduces current concentration in irregular terminal structures, avoids excessively thick or thin local plating, and ensures fine nickel layer crystallization. The processing time is set to 50-150s, which can precisely control the nickel layer thickness to 1-5μm, forming a complete barrier layer (preventing failure due to excessive thinness) and avoiding internal stress cracking due to excessive thickness (ensuring barrier effect). Ultimately, this achieves effective suppression of atomic diffusion between the metal electrode and the functional layer by the nickel layer.

[0056] (7) Gold plating: depositing a gold layer on the surface of a metal electrode.

[0057] In this step, the deposited gold layer is 50-250 nm thick. The gold layer is an inert plating layer, serving as a protective layer to enhance corrosion resistance.

[0058] Specifically, in this step, the processing time is 5-60 seconds, and the current density is 2-6 A / dm³. 2 The operating temperature range is 40-60℃, and the pH value of the gold plating electrolyte is 4.0-5.5.

[0059] Specifically, when depositing a gold layer on the surface, the gold plating electrolyte can be prepared using deionized water, and the formula can be as follows: The concentration of gold salt (calculated as Au) is 1-5 g / L, potassium citrate or sodium citrate is 30-80 g / L, and potassium dihydrogen phosphate is 10-30 g / L.

[0060] Au salts can be potassium gold cyanide.

[0061] By using the above-mentioned gold plating electrolyte formula, high purity and high density of gold layer can be achieved, while taking into account adhesion and cost, and meeting the functional requirements of conductive and corrosion-resistant coating.

[0062] The pH value of the gold plating electrolyte is weakly acidic to near neutral, which can stabilize gold ions and inhibit precipitation. The operating temperature is controlled at a medium temperature of 40-60℃, which can improve the gold ion diffusion rate, promote the effect of additives, and ensure coating uniformity. The process current density is controlled at 2-6 A / dm³. 2Medium and low current densities can ensure fine gold layer crystals and a smooth surface, reducing edge effects and the risk of hydrogen embrittlement; the processing time is adjusted according to the target gold layer thickness.

[0063] (8) Platinum plating: depositing a platinum layer on the surface of a metal electrode.

[0064] In this step, the thickness of the deposited platinum layer is 0.5 μm-1 μm. The platinum layer is a functional layer, possessing catalytic properties, and also serves as an inert coating to block electrolyte diffusion.

[0065] Specifically, in this step, the processing time is 300-1000 seconds, and the current density is 1-2 A / dm³. 2 The operating temperature range is 80-90℃, and the pH range of the platinum plating solution is 8-10.

[0066] In this step, the current density is 1-2 A / dm. 2 This falls within the lower current density range, within which the platinum plating process is more stable, allowing for uniform reduction of platinum ions on the cathode surface. This contributes to obtaining a finely crystalline, uniformly thick platinum coating, reducing porosity and internal stress, and improving the coating's corrosion resistance and oxidation resistance. Simultaneously, the lower current density reduces hydrogen evolution, preventing hydrogen embrittlement from negatively impacting coating quality.

[0067] Specifically, the formulation of the platinum plating electrolyte used in the surface deposition of a platinum layer can be as follows: Platinum salt (such as Pt(NH3)2(NO2)2∙2H2O) 100-300g / L, ammonium nitrate 1000-1100g / L, sodium nitrite 100-150g / L, and adjust the pH value to 8-10 with 28% ammonia water.

[0068] The above-mentioned platinum plating electrolyte formulation has the following advantages: 1. In terms of electrolyte stability, the main salt provides stable platinum ammonium complex ions, ammonium nitrate enhances conductivity and maintains complexation balance through high concentration of ammonium ions, and sodium nitrite helps stabilize platinum ions. Combined with a weakly alkaline environment with a pH of 8-10, it can effectively inhibit the hydrolysis and precipitation of platinum ions, making the platinum plating electrolyte have a long lifespan and be less prone to decomposition, making it suitable for batch continuous production. 2. In terms of coating quality, the slow release of complexed platinum ions, combined with the effect of ammonium nitrate in reducing concentration polarization, can reduce grain size and porosity, resulting in a high-purity platinum coating with high density and smooth surface. Furthermore, the weakly alkaline system can reduce corrosion to the substrate, improve the adhesion between the coating and the underlying layer, and ensure excellent corrosion resistance, oxidation resistance, and wear resistance of the coating.

[0069] Furthermore, a wetting agent can be added to the platinum-plating electrolyte to refine the grain size and improve catalytic activity and surface area. Specifically, the platinum-plating electrolyte also includes 5-200 mg / L of sodium dodecyl sulfate. Experiments have shown that adding a wetting agent can reduce the platinum grain size to below 50 nm, and the prepared metal electrode can operate continuously for more than 14 days in simulated body fluid.

[0070] During steps (2)-(8), a switchable multi-channel electroplating tank can be used to adapt to different metal electrolytes (such as Pt, Ni, Au). The process parameters are dynamically adjusted by monitoring the current density, temperature and pH value in real time. Through refined parameter control (such as current density and time gradient) and multi-channel tank design, efficient switching of different metal coatings can be achieved, resulting in high material utilization and good batch consistency.

[0071] Furthermore, the method for preparing the high-reliability biosensing metal electrode of this application may further include the following steps: (9) Evaluation of coating uniformity and electrochemical properties: The uniformity and electrochemical properties of the coating are evaluated using a three-electrode electrolytic cell system (working electrode, reference electrode, counter electrode).

[0072] Specifically, the prepared metal electrode was subjected to a working voltage in a neutral electrolyte and continuously tested for more than 15 days to verify its long-term stability.

[0073] In this step, the metal electrode of this application is used as the working electrode, a Pt electrode can be used as the counter electrode, and Ag / AgCl can be used as the reference electrode. The electrolyte can be physiological saline.

[0074] The method for fabricating a highly reliable biosensor metal electrode provided in this application has the following advantages: (1) Innovative design of coating structure. Gradient coating design on the surface of metal electrode (such as Cu / Ni / Au / Pt) can take into account conductivity, corrosion resistance and catalytic function. Nickel layer can block diffusion between metal substrate and precious metal, improve the interfacial bonding strength and avoid failure caused by electrochemical incompatibility.

[0075] (2) By designing a reasonable metal coating structure and optimizing electroplating process parameters and dynamic process control, this application can ensure the consistency of coating structure in different batches. Combined with the three-electrode electrolytic cell test system, the surface quality of the metal coating can be evaluated, thus realizing the preparation of low-cost, high-consistency and long-life biosensing electrodes.

[0076] (3) By precisely controlling the composition, thickness and interface matching of each coating layer, taking into account cost, reliability and functional diversity, it is suitable for the preparation of highly integrated bioelectrodes in the field of in vitro diagnostics.

[0077] (4) Relying on mature electroplating technology, through refined parameter control (such as current density, time, temperature and pH) and multi-channel tank design, we can achieve efficient switching of different metal coatings, high material utilization and good batch consistency.

[0078] (5) The entire process can be realized on a standard electroplating production line without the need for complex equipment modification, and is suitable for large-scale production of micro electrode arrays.

[0079] Furthermore, this application also provides a high-reliability biosensing metal electrode, which is prepared using the aforementioned method for preparing a high-reliability biosensing metal electrode. Through an innovative coating architecture design, the withstand voltage test lifespan performance is improved within the framework of mature electroplating processes.

[0080] The present application will be further described below through specific embodiments. Example

[0081] A method for preparing a highly reliable metal electrode for biosensing, the Pt plating process includes the following steps: Step 1: The copper sheet material is stamped into a long strip structure with a width of about 1.5mm to obtain a metal electrode; Step 2: Immerse the metal electrode in a 10% sulfuric acid solution for 10 seconds; In the following steps, a switchable multi-channel electroplating bath is used to dynamically adjust process parameters by monitoring current density, temperature, and pH value in real time: Step 3: Perform cathodic electro-desorption on the metal electrode for 16 seconds at a current density of 4 A / dm³. 2 The pH value of the cathode electrolytic de-electrolyte is 11, the operating temperature is 60℃, and the formula of the cathode electrolytic de-electrolyte used is as follows: Sodium hydroxide 35 g / L, sodium carbonate 30 g / L, trisodium phosphate 35 g / L, sodium silicate 4 g / L, OP emulsifier 2 g / L, sodium gluconate 6 g / L.

[0082] Step 4: Perform electrolytic polishing on the metal electrode for 50 seconds at a current density of 21 A / dm³. 2 The operating temperature is 65℃, the pH value of the electropolishing electrolyte is 2.3, and the formula of the electropolishing electrolyte used is as follows: Phosphoric acid (≥85% by mass) 700ml / L, sulfuric acid (98% by mass) 100ml / L, glycerol 30ml / L, urea 8g / L.

[0083] Step 5: Perform anodic electrostripping on the metal electrode for 16 seconds at a current density of 4 A / dm³. 2The operating temperature is 30℃, and the pH value of the anolyte is 1.5. The formulation of the anolyte can be as follows: Phosphoric acid (85% concentration) 150ml / L, sulfuric acid (98% concentration) 75ml / L, nitric acid (68% concentration) 20ml / L, urea 8g / L.

[0084] Step 6: Activate the metal electrode by treating it with 4 mol / L sulfuric acid for 17 seconds.

[0085] Step 7: Copper plating, processing time is 101s, current density is 11 A / dm³ 2 The operating temperature is 30℃, the pH value of the copper plating electrolyte is 1.3, the copper plating thickness is 4μm, and the formula of the copper plating electrolyte used is as follows: CuSO4·5H2O 200g / L, H2SO4 (98% mass concentration) 65g / L, HCl 55mg / L, 0.3g / L leveling agent (benzimidazole quaternary ammonium salt (BIABDGE)).

[0086] Step 8: Ni plating, processing time 101s, current density 6 A / dm³ 2 The nickel plating electrolyte has a pH of 4.0, an operating temperature of 55℃, and a nickel plating thickness of 3μm. The formulation of the nickel plating electrolyte used is as follows: Nickel sulfate (NiSO4·6H2O) 250g / L, nickel chloride (NiCl2·6H2O) 45g / L, boric acid (H3BO3) 40g / L.

[0087] Step 9: Gold plating, processing time is 11 seconds, current density is 4 A / dm³ 2 The operating temperature is 50℃, the pH value of the gold plating electrolyte is 4.5, the gold plating thickness is 70nm, and the formula of the gold plating electrolyte used is as follows: Potassium gold cyanide (KAu(CN)2) concentration 3 g / L, potassium citrate 55 g / L, potassium dihydrogen phosphate 20 g / L.

[0088] Step 10: Pt plating, processing time 481s, current density 1.5 A / dm³ 2 The operating temperature is 85℃, the pH value of the platinum plating solution is 9, the platinum plating thickness is 0.9μm, and the formulation of the platinum plating electrolyte used is as follows: Pt(NH3)2(NO2)2∙2H2O 200g / L, ammonium nitrate 1050g / L, sodium nitrite 125g / L, sodium dodecyl sulfate 100mg / L, and adjust the pH to 9 with 28% ammonia solution.

[0089] The metal electrode prepared by the method in this embodiment has the following surface morphology. Figure 1 and Figure 2 As shown, where, Figure 1 For a magnification of 1k, Figure 2 The magnification is 50k. From Figure 1 and Figure 2 It can be seen that the surface of the metal electrode is relatively smooth and flat, and the coating has good density.

[0090] The metal electrodes were surrounded by nail polish, leaving only about 1mm exposed on both the front and back sides. 2 The area was determined, and the electrode was placed in a three-electrode electrolytic cell system with physiological saline as the electrolyte, using a Pt electrode as the counter electrode and Ag / AgCl as the reference electrode. A constant potential of 0.6V was applied to test the It performance curve, as shown in the test curve. Figure 3 As shown, after 15 consecutive days of testing, the current stabilized at the nA level.

[0091] Comparative Example The preparation method of the comparative metal electrode is the same as that of Example 1, except that no wetting agent is added to the platinum plating electrolyte.

[0092] The surface morphology of the metal electrode prepared in Example 1 and the metal electrode prepared in the comparative example were observed at the same magnification. The results are as follows: Figure 4 As shown, the left image shows the surface state of the metal electrode prepared in Example 1, and the right image shows the surface state of the metal electrode prepared in the comparative example. Figure 4 It can be seen that the metal electrode prepared in Example 1 has a smooth and flat surface and good coating density, while the Pt metal electrode prepared in the comparative example has larger grains and a less dense coating.

[0093] It should be understood that the application of this application is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of this application.

Claims

1. A method for preparing a highly reliable biosensing metal electrode, characterized in that, Includes the following steps: S1. Deposit a nickel layer on the surface of the metal electrode: the thickness of the nickel layer is 1-5 μm; S2. Deposit a gold layer on the surface of the metal electrode: the thickness of the gold layer is 50-250 nm; S3. Deposit a platinum layer on the surface of the metal electrode: the thickness of the platinum layer is 0.5 μm-1 μm; The platinum plating electrolyte used in the platinum deposition process contains a wetting agent.

2. The method for preparing a high-reliability biosensing metal electrode according to claim 1, characterized in that, When the substrate of the metal electrode is copper, the following steps are included before step S1: S0. Deposit a copper layer on the surface of the metal electrode: the thickness of the copper layer is 3-6 μm.

3. The method for preparing a high-reliability biosensing metal electrode according to claim 2, characterized in that, The copper deposition process takes 80-150 seconds and uses a current density of 9-15 A / dm³. 2 The operating temperature range is 20-40℃, and the pH value of the copper plating electrolyte is 0.8-1.

8. The formulation of the copper plating electrolyte is as follows: CuSO4·5H2O 180-220g / L, H2SO4 50-80g / L, chloride ions 30-80mg / L, leveling agent 0.1-0.5g / L; The leveling agent is one of nitrogen-containing biphenyl compounds and their quaternary ammonium salt derivatives.

4. The method for preparing a high-reliability biosensing metal electrode according to claim 1, characterized in that, The process of depositing the nickel layer involves a current density of 2-8 A / dm³. 2 The processing time is 50-150 seconds, the pH value of the nickel plating electrolyte is in the working range of 3.5-5.0, and the working temperature is in the range of 45-65℃. The formulation of the nickel plating electrolyte is as follows: Nickel sulfate 200-300 g / L, nickel chloride 30-60 g / L, boric acid 30-50 g / L.

5. The method for preparing a high-reliability biosensing metal electrode according to claim 1, characterized in that, The gold deposition process takes 5-60 seconds and uses a current density of 2-6 A / dm³. 2 The operating temperature range is 40-60℃, and the pH range of the gold plating electrolyte is 4.0-5.

5. The formula for the gold plating electrolyte is as follows: Gold salt 1-5g / L, potassium citrate or sodium citrate 30-80g / L, potassium dihydrogen phosphate 10-30g / L; The gold salt is potassium gold cyanide.

6. The method for preparing a high-reliability biosensing metal electrode according to claim 1, characterized in that, The platinum layer deposition process takes 300-1000 seconds and uses a current density of 1-2 A / dm³. 2 The operating temperature range is 80-90℃, the pH value of the platinum plating solution is 8-10, and the wetting agent is sodium dodecyl sulfate. The formulation of the platinum plating electrolyte is as follows: Platinum salt 100-300 g / L, ammonium nitrate 1000-1100 g / L, sodium nitrite 100-150 g / L, sodium dodecyl sulfate 5-200 mg / L, and the pH value is adjusted to 8-10 with ammonia.

7. The method for preparing a high-reliability biosensing metal electrode according to claim 2, characterized in that, Following step S0, the following steps are also included: The metal electrode is immersed in a sulfuric acid solution with a concentration of 3-5 mol / L for 10-30 seconds.

8. The method for preparing a high-reliability biosensing metal electrode according to claim 1, characterized in that, Before proceeding to step S1, the following steps are also included: The desired metal electrode is formed by etching or stamping the metal substrate according to the desired structure of the metal electrode, and the surface of the metal electrode is pretreated. The metal electrode is first subjected to cathodic desorption treatment, and then electrolytic polishing treatment. The metal electrode is subjected to anodic electro-desorption treatment; The surface of the metal electrode is activated.

9. The method for preparing a high-reliability biosensing metal electrode according to claim 8, characterized in that, The metal substrate is one of copper and nickel; The surface pretreatment is one or two of alkaline washing, acid washing, or surfactant cleaning. The cathode electro-desorption process takes 10-20 seconds and has a current density of 3-5 A / dm³. 2 The working pH range of the cathode electrolytic de-electrolyte is 10.5~13.0, and the working temperature range is 50~80℃; The formulation of the cathode electrolytic de-electrolyte is as follows: Sodium hydroxide 30~40 g / L, sodium carbonate 25~35 g / L, trisodium phosphate 30~40 g / L, sodium silicate 3~5 g / L, OP emulsifier 1~3 g / L, sodium gluconate 5~8 g / L; The electropolishing process involves a processing time of 20-50 seconds and a current density of 15-25 A / dm². 2 The operating temperature range is 60~70℃, and the pH value of the electropolishing electrolyte is 2.0~2.

5. The anodic electro-desorption process has a processing time of 10-20 seconds and a current density of 1-5 A / dm³. 2 The operating temperature range is 20~40℃, and the pH value of the anolyte deionization electrolyte is 1.0~2.

0. The formulation of the anolyte for deionization is as follows: Phosphoric acid 100~200ml / L, sulfuric acid 50~100ml / L, nitric acid 10~30ml / L, urea 5~10g / L; The activation process specifically involves immersing the metal electrode in a sulfuric acid solution with a concentration of 3-5 mol / L for 10-30 seconds.

10. A highly reliable biosensing metal electrode, characterized in that, The metal electrode for high-reliability biosensing is prepared using the method described in any one of claims 1-9 above.

Images