Low-temperature curing platinum paste for oximeter catalytic electrode and preparation method of low-temperature curing platinum paste

Abstract

The invention provides low-temperature curing platinum paste for a catalytic electrode of an oximeter and a preparation method of the low-temperature curing platinum paste. The low-temperature curing platinum paste for the catalytic electrode of the oximeter comprises the following components in parts by weight: 40-80% of modified nano platinum powder, 0-20% of micron-sized platinum powder, 3-10% of macromolecular resin, 12-40% of an organic solvent and 0.5-2% of a dispersing agent, the particle size range of the modified nano platinum powder is 40-300nm, and the particle size range of the micron-sized platinum powder is 1-3mu m; the polymer resin is thermosetting resin and / or thermoplastic resin; the viscosity of the low-temperature curing platinum paste for the oximeter catalytic electrode is 15-40 pa.s / 25 DEG C. According to the invention, the low-temperature curing at 100-150 DEG C is realized by using the adaptive resin and the organic solvent in a specific proportion; the composite material is suitable for application of a PET / PI flexible base material and a low-temperature sensitive functional material, and is matched with a silk-screen printing process, so that the equipment investment and the production cost are greatly reduced, and the production efficiency is improved.

Description

Technical Field

[0001] This invention relates to the field of electronic paste technology, and in particular to a low-temperature curing platinum paste for the catalytic electrode of a pulse oximeter and its preparation method. Background Technology

[0002] The partial pressure of dissolved oxygen in blood is a crucial physiological indicator for the human body, directly impacting normal tissue metabolism and overall health. Currently, the most common method for measuring blood oxygen partial pressure is arterial blood gas analysis, which utilizes the Clark oxygen electrode as its core detection element. The Clark oxygen electrode is a polarographic electrode specifically designed for measuring dissolved oxygen content in liquids. Its detection mechanism relies on the current generated by the redox reaction on the electrode surface to reflect the dissolved oxygen concentration in the solution. This electrode uses a breathable membrane to block most impurities in the solution, allowing only oxygen to permeate and contact the working electrode, thus generating a diffusion current. The magnitude of this current is directly proportional to the dissolved oxygen content in the solution. Structurally, the Clark oxygen electrode mainly consists of a platinum cathode, a silver / silver chloride anode, an inner potassium chloride electrolyte layer, and an outer permeable membrane. During detection, oxygen in the blood permeates through the permeable membrane to the electrode surface. Under a specific voltage of 0.6-0.9V, a reduction reaction occurs at the cathode, simultaneously generating a stable current. By detecting changes in this current, the partial pressure of oxygen in the blood can be accurately measured. The core function of a pulse oximeter is to achieve real-time monitoring of blood oxygen saturation based on the above principle. As the core component of the pulse oximeter, the performance of the catalytic electrode directly determines the detection accuracy, response speed, and lifespan.

[0003] Currently, the conductive catalytic layer of the catalytic electrode of pulse oximeters is generally prepared by vacuum coating process. This process has problems such as large equipment investment, complex production process and high cost. In addition, traditional platinum paste is mostly high-temperature sintering type (sintering temperature is generally above 650℃), which cannot be used on flexible substrates such as PI / PET of pulse oximeters.

[0004] Therefore, it is necessary to design a low-temperature curing platinum paste for the catalytic electrode of a pulse oximeter and its preparation method to solve the above problems. Summary of the Invention

[0005] The purpose of this invention is to provide a low-temperature curing platinum paste for pulse oximeter catalytic electrodes that is compatible with screen printing processes, balances electrode conductivity and catalytic site density, and has high catalytic activity, as well as its preparation method.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: a low-temperature curing platinum paste for a pulse oximeter catalytic electrode, comprising the following components in parts by weight: 40%-80% modified nano-platinum powder, 0-20% micron-sized platinum powder, 3%-10% polymer resin, 12%-40% organic solvent, and 0.5%-2% dispersant; the modified nano-platinum powder is prepared by reacting nano-platinum powder with an aromatic diazonium salt containing hydrophilic groups, the particle size range of the modified nano-platinum powder is 40-300 nm, and the particle size range of the micron-sized platinum powder is 1-3 μm; the polymer resin is a thermosetting resin and / or a thermoplastic resin; the viscosity of the low-temperature curing platinum paste for the pulse oximeter catalytic electrode is 15-40 Pa·s / 25℃.

[0007] As a further improvement to the present invention, the modified nano-platinum powder is prepared by the following method: s1. Preparation of aromatic diazonium salt solution: In an ice-water bath, sodium nitrite solution is added dropwise to an acidic solution of primary aromatic amine to carry out the diazotization reaction; s2. Surface modification reaction of nano-platinum powder: Then, nano-platinum powder is added to the above diazonium salt solution and stirred at a speed of 100-300 rpm for 1-2 hours. s3. After the reaction, the nano-platinum powder is precipitated, the upper layer solution is poured out, and the nano-platinum powder precipitate is vacuum dried to obtain surface-hydrophilic modified nano-platinum powder.

[0008] As a further improvement of the present invention, in step s1, the primary aromatic amine has a benzene ring with an amino group, as well as a carboxyl group or a sulfonic acid group, and the pH value of the acidic solution of the primary aromatic amine is 2.5-3.5.

[0009] As a further improvement of the present invention, in step s1, the molar ratio of sodium nitrite to primary aromatic amine in the reaction solution is (1-1.5):1.

[0010] As a further improvement of the present invention, the nano-platinum powder is spherical platinum powder with a particle size range of 40-200nm.

[0011] As a further improvement of the present invention, the polymer resin is selected from one or more of epoxy resin, polyurethane resin, and polyester resin.

[0012] As a further improvement of the present invention, the organic solvent is selected from one or more of diethylene glycol ethyl ether acetate, DBE, diethylene glycol butyl ether acetate, propylene glycol methyl ether acetate, diethylene glycol ethyl ether, and diethylene glycol butyl ether.

[0013] As a further improvement of the present invention, the dispersant is BYK-161 or BYK-163.

[0014] As a further improvement of the present invention, the curing temperature of the low-temperature curing platinum paste for the pulse oximeter catalytic electrode is 100-150℃.

[0015] To achieve the above objectives, the present invention adopts the following technical solution: a method for preparing a low-temperature curing platinum paste for a pulse oximeter catalytic electrode as described in any one of the above claims, comprising the following steps: S1. Mix the polymer resin with the organic solvent, heat and stir for 1-2 hours at a stirring speed of 500-1000 rpm and a heating temperature of 60-80℃. After dissolving, cool to room temperature. S2. Then add the modified nano-platinum powder, micron-sized platinum powder, dispersant and the remaining organic solvent in sequence, mix and stir for 0.5-1h at a stirring speed of 100-200rpm. S3. Grind with three rollers to a fineness of ≤10μm.

[0016] As can be seen from the above technical solutions, the low-temperature curing platinum paste for the catalytic electrode of the pulse oximeter of the present invention has the following advantages: 1. The platinum paste of this invention uses suitable thermosetting resins and / or thermoplastic resins, combined with a specific proportion of organic solvents, to achieve low-temperature curing at 100-150℃. This avoids damage to the substrate caused by high temperatures, is suitable for flexible substrates and low-temperature sensitive functional materials, and can also meet the curing requirements of screen printing processes. It can replace vacuum coating processes without complex equipment modifications, significantly reducing equipment investment and production costs, and improving production efficiency. 2. The modified nano-platinum powder of this invention is prepared by reacting nano-platinum powder with an aromatic diazonium salt containing hydrophilic groups. The introduction of hydrophilic groups effectively improves the hydrophilicity of the nano-platinum powder. Simultaneously, the addition of 0.5%-2% dispersant further enhances the uniformity of platinum powder dispersion in resin and organic solvent systems. Furthermore, the use of a compound scheme of modified nano-platinum powder and micron-sized platinum powder provides hydrophilicity and catalytic active sites, ensuring a high-density distribution of catalytic sites, while the micron-sized platinum powder provides a framework to increase conductivity between nano-platinum powders, optimizing the conductive pathways within the electrode. After film formation, both conductivity and catalytic performance remain stable, avoiding fluctuations in detection accuracy caused by uneven dispersion. 3. The viscosity of the platinum paste is precisely controlled between 15-40 Pa·s. This viscosity range is perfectly matched with the mesh size and printing speed of screen printing, which not only ensures the smoothness of the paste printing, but also precisely controls the film thickness, effectively avoiding molding defects such as sagging, pinholes, and mesh residue. After curing, the surface of the platinum electrode is uniform and dense.

[0017] 4. Modified nano-platinum powder and micron-sized platinum powder provide sufficient catalytic active sites and a stable conductive network. The polymer resin ensures the mechanical strength and adhesion after film formation. With the synergistic effect of each component, the pulse oximeter catalytic electrode prepared by screen printing has advantages such as fast detection response speed, high accuracy of blood oxygen saturation detection, and good stability. Attached Figure Description

[0018] Figure 1 SEM image of the modified nano-platinum powder prepared according to the present invention.

[0019] Figure 2 The linear relationship between current and oxygen partial pressure was measured for the Clark oxygen electrode sample prepared with platinum paste in Example 2 within the range of oxygen partial pressure from 0 to 760 mmHg.

[0020] Figure 3 The surface SEM image of the circular electrode sample prepared from the platinum paste in Example 2. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0022] Example 1

[0023] Step 1: Preparation of modified nano-platinum powder: s1. Preparation of aromatic diazonium salt solution: Prepare 100 mL of 3M hydrochloric acid solution and 200 mL of 1M sodium nitrite solution for later use. Accurately weigh 13.7 g of p-aminobenzoic acid and add it to the hydrochloric acid solution. Stir at 600 rpm to form an acidic solution of p-aminobenzoic acid with pH=3. Then, in an ice-water bath at 0-5℃, add the sodium nitrite solution dropwise to the acidic solution of p-aminobenzoic acid (the molar ratio of sodium nitrite to p-aminobenzoic acid is 1.1:1) to induce a diazotization reaction and generate an aromatic diazonium salt solution. s2. Surface modification reaction of nano-platinum powder: Add nano-platinum powder (Kunming Yunrui Technology Co., Ltd., model PT-50, particle size 40-200nm, spherical platinum powder) to the above diazonium salt solution and stir the reaction. The stirring speed is 200rpm and the stirring time is 1H. The weight ratio of diazonium salt solution to nano-platinum powder is 10:1. s3. After the reaction, the nano-platinum powder is allowed to settle, the upper layer of solution is poured off, and the nano-platinum powder is dried in a vacuum oven at 60℃ for 2 hours to obtain surface-hydrophilically modified nano-platinum powder; please refer to... Figure 1 The particle size range of the modified nano-platinum powder is 40-300nm.

[0024] Step 2: Preparation of organic carrier: Polyurethane resin and diethylene glycol ethyl ether acetate are added to a container according to the weight ratio in Table 1 and mixed. The mixture is then heated in a constant temperature water bath at 80°C and stirred at 1000 r / min. After complete dissolution, the mixture is kept at this temperature for 2 hours to obtain the organic carrier for later use.

[0025] Step 3: Then, according to the weight ratio in Table 1, add the modified nano-platinum powder, dispersant (BYK-161, German BYK Chemicals) and DBE diester to the organic carrier in sequence, mix and stir for 1 hour at a stirring speed of 100 rpm.

[0026] Step 4: Transfer the above mixture to a three-roll mill and grind it to a fineness ≤10μm. The viscosity of the resulting platinum slurry is 38 Pa·s / 25℃.

[0027] Example 2

[0028] Step 1: Preparation of modified nano-platinum powder: Same as in Example 1.

[0029] Step 2, Preparation of organic carrier: Polyurethane resin and diethylene glycol ethyl ether acetate are added to a container according to the weight ratio in Table 1 and mixed. The mixture is then placed in a constant temperature water bath at 80°C and heated at 1000 r / min. After complete dissolution, the mixture is kept at this temperature for 2 hours to obtain the organic carrier for later use. Step 3: Then, according to the weight ratio in Table 1, add the modified nano-platinum powder, micron-sized platinum powder (PT-02, Kunming Yunrui Technology Co., Ltd., particle size 1-3um), dispersant (BYK-163, German BYK Chemicals) and DBE diester to the organic carrier in sequence, mix and stir for 0.5h at a stirring speed of 200rpm. Step 4: Transfer the above mixture to a three-roll mill and grind it to a fineness ≤10μm. The viscosity of the resulting platinum slurry is 15 Pa·s / 25℃.

[0030] Example 3

[0031] Step 1: Preparation of modified nano-platinum powder: Same as in Example 1.

[0032] Step 2, Preparation of organic carrier: Polyester resin and solvent DBE diester are added to a container according to the weight ratio in Table 1 and mixed. The mixture is then heated in a constant temperature water bath at 80°C and stirred at 1000 r / min. After complete dissolution, the mixture is kept at this temperature for 2 hours to obtain the organic carrier for later use. Step 3: Then, according to the weight ratio in Table 1, add the modified nano-platinum powder, dispersant (BYK-161, German BYK Chemicals) and the remaining DBE diester to the organic carrier in sequence, mix and stir for 0.5 h at a stirring speed of 200 rpm. Step 4: Transfer the above mixture to a three-roll mill and grind it to a fineness ≤10μm. The viscosity of the resulting platinum slurry is 18 Pa·s / 25℃.

[0033] Comparative Example 1 Step 1: Preparation of organic carrier: Polyurethane resin and diethylene glycol ethyl ether acetate are added to a container according to the weight ratio in Table 1 and mixed. The mixture is then heated in a constant temperature water bath at 80°C and stirred at 1000 r / min. After complete dissolution, the mixture is kept at this temperature for 2 hours to obtain the organic carrier for later use. Step 2: Then, according to the weight ratio in Table 1, add micron-sized platinum powder (PT-02, Kunming Yunrui Technology Co., Ltd., particle size 1-3um), dispersant (BYK Chemical, Germany, model BYK-163) and DBE diester to the organic carrier in sequence, mix and stir for 0.5h at a stirring speed of 200rpm. Step 3: Transfer the above mixture to a three-roll mill and grind it to a fineness ≤10μm. The viscosity of the resulting platinum slurry is 13 Pa·s / 25℃.

[0034] Comparative Example 2 Step 1: Preparation of organic carrier: Polyester resin and solvent DBE diester are added to a container according to the weight ratio in Table 1 and mixed. The mixture is then heated in a constant temperature water bath at 80°C and stirred at 1000 r / min. After complete dissolution, the mixture is kept at this temperature for 2 hours to obtain the organic carrier for later use. Step 2: Then, according to the weight ratio in Table 1, add micron-sized platinum powder (PT-02, Kunming Yunrui Technology Co., Ltd., particle size 1-3um), dispersant (BYK-161, German BYK Chemicals) and the remaining DBE diester to the organic carrier in sequence, mix and stir for 0.5h at a stirring speed of 200rpm. Step 3: Transfer the above mixture to a three-roll mill and grind it to a fineness ≤10μm. The viscosity of the resulting platinum slurry is 52 Pa·s / 25℃.

[0035] Comparative Example 3 Step 1: Preparation of organic carrier: Polyurethane resin and diethylene glycol ethyl ether acetate are added to a container according to the weight ratio in Table 1 and mixed. The mixture is then heated in a constant temperature water bath at 80°C and stirred at 1000 r / min. After complete dissolution, the mixture is kept at this temperature for 2 hours to obtain the organic carrier for later use. Step 2: Then, according to the weight ratio in Table 1, add nano-platinum powder (Kunming Yunrui Technology Co., Ltd., model PT-50, particle size 40-200nm, spherical platinum powder), micron-sized platinum powder (PT-02, Kunming Yunrui Technology Co., Ltd., particle size 1-3um), dispersant (Germany BYK Chemical, model BYK-163) and DBE diester to the organic carrier in sequence, mix and stir for 0.5h at a stirring speed of 200rpm; Step 3: Transfer the above mixture to a three-roll mill and grind it to a fineness ≤10μm. The viscosity of the resulting platinum slurry is 13 Pa·s / 25℃.

[0036] Table 1. Composition of platinum pastes in the examples and comparative examples.

[0037] The platinum paste prepared in the above examples and comparative examples was screen-printed onto a PET substrate to form circular electrode samples with a pattern of φ5mm and a thickness of 0.5mm, and then dried at 130℃ for 10 minutes. The samples were then subjected to the following tests: Adhesion test: Use 3M tape to test the adhesion of the cured electrode layer; please refer to Table 2 for the results. 5B is the best, indicating no peeling, and 0B is the worst, indicating complete peeling.

[0038] Sheet resistance test: The sheet resistance of the sample was tested using a four-probe tester; the results are shown in Table 2.

[0039] Furthermore, Clark oxygen electrode samples for pulse oximeters were prepared using the aforementioned circular electrode samples, and their performance was tested: First, a Clark oxygen electrode sample was prepared by using Ag / AgCl as a reference electrode, coating the inner layer with potassium chloride electrolyte, and the outer layer with a polytetrafluoroethylene breathable membrane; then, a mixture of oxygen and nitrogen was introduced into 5 mL of 10 mM PBS solution, and PBS solutions with different dissolved oxygen partial pressures were obtained by adjusting the flow ratio of oxygen and nitrogen; finally, using a DY2000 electrochemical workstation, the current value was measured with a liquid sample volume of 50 μL and a reduction voltage of 0.6 V. The linear relationship between the test current and oxygen partial pressure of the Clark oxygen electrode sample within the range of 0-760 mmHg was obtained. The results are shown in Table 2. Figure 2 .

[0040] Table 2 Performance Test Table of Platinum Paste in Examples and Comparative Examples

[0041] Comparing Example 2 and Comparative Example 1, it can be found that using a modified nano-platinum powder and micron-platinum powder composite scheme can improve the surface density of the catalytic electrode formed by platinum slurry (please refer to Example 2). Figure 3The platinum catalytic electrode prepared in Example 2 exhibits a dense microstructure (as shown by SEM testing) and good circuit conductivity (appropriate sheet resistance); furthermore, when applied to the Clark oxygen electrode, its linear response is significantly improved (see [reference needed]). Figure 2 ), Explanation of modified nano-platinum powder PT-50 (please refer to) Figure 1 Compared to micron-sized platinum powder, it has a higher specific surface area, more catalytic active sites, higher catalytic sensitivity, and better linearity.

[0042] Comparing Example 2 and Comparative Example 3, it can be further found that compared with the combination of ordinary nano-platinum powder and micron-platinum powder, the combination of modified nano-platinum powder and micron-platinum powder still has the advantage in linear response, which further illustrates that the modified nano-platinum powder provides hydrophilicity and catalytic active sites, and the linear response of the oxygen electrode is improved.

[0043] In addition, Comparative Example 2 shows that although increasing the amount of micron-sized platinum powder can improve the linear response of the oxygen electrode, the platinum powder content is too high, resulting in too little polymer resin, poor adhesion, and easy detachment of the platinum powder on the surface. When coating the electrolyte and the breathable membrane, the platinum catalytic electrode is prone to detachment.

[0044] The above embodiments are only used to illustrate the present invention and are not intended to limit the technical solutions described in the present invention. The understanding of this specification should be based on those skilled in the art. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still make modifications or equivalent substitutions to the present invention. All technical solutions and improvements that do not depart from the spirit and scope of the present invention should be covered within the scope of the claims of the present invention.

Claims

1. A low-temperature curing platinum paste for a pulse oximeter catalytic electrode, characterized in that, The product contains the following components in parts by weight: 40%-80% modified nano-platinum powder, 0-20% micron-sized platinum powder, 3%-10% polymer resin, 12%-40% organic solvent, and 0.5%-2% dispersant; the modified nano-platinum powder is prepared by reacting nano-platinum powder with an aromatic diazonium salt containing hydrophilic groups, the particle size range of the modified nano-platinum powder is 40-300 nm, and the particle size range of the micron-sized platinum powder is 1-3 μm; the polymer resin is a thermosetting resin and / or a thermoplastic resin; the low-temperature curing platinum paste for the pulse oximeter catalytic electrode has a viscosity of 15-40 Pa·s / 25℃.

2. The low-temperature curing platinum paste for the catalytic electrode of a pulse oximeter as described in claim 1, characterized in that: The modified nano-platinum powder was prepared using the following method: s1. Preparation of aromatic diazonium salt solution: In an ice-water bath, sodium nitrite solution is added dropwise to an acidic solution of primary aromatic amine to carry out the diazotization reaction; s2. Surface modification reaction of nano-platinum powder: Then, nano-platinum powder is added to the above diazonium salt solution and stirred at a speed of 100-300 rpm for 1-2 hours. s3. After the reaction, the nano-platinum powder is precipitated, the upper layer solution is poured out, and the nano-platinum powder precipitate is vacuum dried to obtain surface-hydrophilic modified nano-platinum powder.

3. The low-temperature curing platinum paste for the catalytic electrode of a pulse oximeter as described in claim 2, characterized in that: In step s1, the primary aromatic amine has a benzene ring with an amino group, as well as a carboxyl or sulfonic acid group, and the pH value of the acidic solution of the primary aromatic amine is 2.5-3.

5.

4. The low-temperature curing platinum paste for the catalytic electrode of a pulse oximeter as described in claim 2, characterized in that: In step s1, the molar ratio of sodium nitrite to primary aromatic amine in the reaction solution is (1-1.5):

1.

5. The low-temperature curing platinum paste for the catalytic electrode of a pulse oximeter as described in claim 2, characterized in that: The nano-platinum powder is spherical platinum powder with a particle size range of 40-200 nm.

6. The low-temperature curing platinum paste for the catalytic electrode of a pulse oximeter as described in claim 1, characterized in that: The polymer resin is selected from one or more of epoxy resin, polyurethane resin, and polyester resin.

7. The low-temperature curing platinum paste for the catalytic electrode of a pulse oximeter as described in claim 1, characterized in that: The organic solvent is selected from one or more of diethylene glycol ethyl ether acetate, DBE, diethylene glycol butyl ether acetate, propylene glycol methyl ether acetate, diethylene glycol ethyl ether, and diethylene glycol butyl ether.

8. The low-temperature curing platinum paste for the catalytic electrode of a pulse oximeter as described in claim 1, characterized in that: The dispersant is BYK-161 or BYK-163.

9. The low-temperature curing platinum paste for the catalytic electrode of a pulse oximeter as described in claim 1, characterized in that: The curing temperature of the low-temperature curing platinum paste used for the pulse oximeter catalytic electrode is 100-150℃.

10. A method for preparing a low-temperature curing platinum paste for a pulse oximeter catalytic electrode as described in any one of claims 1-9, comprising the following steps: S1. Mix the polymer resin with the organic solvent, heat and stir for 1-2 hours at a stirring speed of 500-1000 rpm and a heating temperature of 60-80℃. After dissolving, cool to room temperature. S2. Then add the modified nano-platinum powder, micron-sized platinum powder, dispersant and the remaining organic solvent in sequence, mix and stir for 0.5-1h at a stirring speed of 100-200rpm. S3. Grind with three rollers to a fineness of ≤10μm.

Images