An integrated electrocardio electrode chip, a preparation method thereof and an electrocardio electrode

Abstract

The application discloses an integrated ECG electrode chip, a preparation method thereof and an ECG electrode, and belongs to the field of medical devices. The electrode chip is integrally formed by injection molding of a conductive composite material, and comprises a base body and a lead buckle female buckle. The raw materials include, by weight percentage, medical grade ABS 62-72%, conductive carbon black 20-23%, silver chloride 5-13%, and an auxiliary agent. The preparation method comprises the following steps: drying the ABS; activating and modifying the carbon black, AgCl and coupling agent; mixing and granulating; injection molding of the electrode chip blank; and then surface activation treatment with acid liquor to enrich the surface layer with AgCl, so as to obtain the electrode chip. The application replaces the traditional copper-silver plating structure with inexpensive carbon black and silver chloride, significantly reduces the raw material and manufacturing costs through the integrated injection molding and surface activation process, while ensuring the low AC impedance (≤3kΩ) and low polarization voltage (≤100mV) of the electrode, fully meeting the requirements of the YY / T0196-2005 national standard, and being suitable for various scenes from ordinary monitoring to diagnostic ECG.

Description

Technical Field

[0001] This invention relates to the field of medical device technology, specifically to an integrated electrocardiogram (ECG) electrode chip, its preparation method, and the ECG electrode itself. Background Technology

[0002] Disposable ECG electrodes are essential consumables in clinical monitoring and electrocardiogram (ECG) examinations. Their core component is the "electrode clip" or "electrode chip," which contacts the conductive hydrogel and transmits bioelectrical signals to the leads. Traditional ECG electrode chips typically employ a combination of a metal base and a metal clip. Specifically, a common process involves fixing a silver-plated copper or silver-plated stainless steel female clip to a plastic substrate via riveting or embedding. This design relies heavily on the silver plating layer to provide excellent conductivity and low polarization voltage, ensuring accurate acquisition of ECG signals.

[0003] However, this traditional copper-plated silver electrode chip has several inherent technical and cost drawbacks. First, raw material costs are high. Copper and silver are both precious metals, and their prices have been rising continuously in recent years, keeping the material costs of the electrode chip high. Second, the manufacturing process is complex and costly. Traditional processes require the separate preparation of the plastic substrate and metal clips, followed by riveting or inlay assembly, involving multiple steps such as stamping, electroplating, injection molding, and riveting. This results in low production efficiency, and the electroplating process is environmentally unfriendly. Furthermore, the silver plating layer is prone to oxidation or wear during long-term use or storage, leading to increased electrode impedance and decreased signal quality. In addition, the metal clip and plastic substrate may loosen due to weak bonding, affecting product reliability.

[0004] To reduce costs, the industry has tried various alternatives, such as filling a plastic matrix with conductive carbon black and directly forming conductive plastic electrodes through injection molding. While this approach eliminates the need for metal parts and riveting, conductive plastics themselves typically lack depolarization capabilities, resulting in high electrode polarization voltages and severe baseline drift. This makes it unsuitable for high-precision electrocardiographs and can only be used for simple monitoring where signal quality requirements are extremely low.

[0005] Another option is to coat the conductive plastic surface with a coating containing silver or silver chloride. However, this option is either prone to peeling due to poor coating adhesion, or it involves additional steps and costs due to coating processes (such as spraying or screen printing), and the amount of precious metals used in the coating is still considerable.

[0006] Therefore, developing a new type of ECG electrode chip that can significantly reduce raw material and manufacturing costs, ensure low impedance and low polarization voltage, and has an environmentally friendly process suitable for large-scale mass production is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0007] To solve the above-mentioned technical problems, the present invention provides an integrated electrocardiogram electrode chip, including a substrate and a lead snap female integrated into the substrate; The raw material composition of the conductive composite material includes, by weight percentage: Medical-grade ABS resin 62%–72%; Conductive carbon black 20%–23%; Silver chloride powder 5%–13%; And 1%–3% of additives; The additives include at least coupling agents, lubricants, and antioxidants; The surface of the electrode chip is formed with a silver chloride layer enriched by acid activation treatment.

[0008] Preferably, the raw material composition of the conductive composite material is as follows (by weight percentage): Medical-grade ABS resin 67%; Conductive carbon black 22%; 9% silver chloride powder; Coupling agent 0.6%; Lubricant 1.0%; Antioxidant 0.4%.

[0009] Preferably, the conductive carbon black is acetylene black with a particle size of 30-50 nm; The silver chloride powder has a purity of ≥99.5% and a particle size in the micrometer range.

[0010] The method for fabricating an integrated ECG electrode chip includes the following steps: S1. Raw material pretreatment: The medical-grade ABS resin is dried to reduce its moisture content to less than 0.1%; the conductive carbon black, silver chloride powder and coupling agent are mixed and activated in a high-speed mixer to obtain the modified filler; S2, Premix: The dried medical-grade ABS resin, modified filler and remaining additives are mixed to obtain a premix; S3. Granulation: The premixed material is fed into a twin-screw extruder for melt blending, extrusion, cooling, pelletizing and drying to obtain conductive composite material particles; S4. Injection molding: The conductive composite material particles are added to an injection molding machine and integrally injection molded through a mold to obtain an electrode chip blank containing a lead-connecting snap-fit ​​female buckle; S5. Surface activation: The electrode chip preform is immersed in acid solution to enrich its surface with silver chloride, and then cleaned and dried to obtain the integrated ECG electrode chip.

[0011] Preferably, in step S1, the drying conditions for the ABS resin are: drying in an 80°C hot air oven for 4 hours; The specific steps for activating the filler are as follows: conductive carbon black and silver chloride powder are put into a high-speed mixer, silane coupling agent and anhydrous ethanol are added, and the mixture is stirred at high speed for 25 minutes at 110°C to allow the ethanol to evaporate and complete the surface modification of the powder. The premixing step involves mixing at low speed for 15 minutes at 60°C in a mixer.

[0012] Preferably, in step S3, the segmented temperature control of the twin-screw extruder is as follows: Zone 1 210℃, Zone 2 225℃, Zone 3 232℃, and Die 230℃, with a screw speed of 300 rpm; after extrusion, the material is water-cooled, stretched, and pelletized, and then dried at 80℃ for 2 hours.

[0013] Preferably, in step S4, the injection molding process parameters are: mold preheating temperature 75-85℃, barrel temperature 220-230℃, injection pressure 70-90 bar, holding time 3 seconds, and cooling and setting time 12 seconds; the molded blank is left to stand at room temperature for 24 hours to release internal stress.

[0014] Preferably, in step S5, the acid solution is 5% dilute hydrochloric acid, the soaking time is 3 minutes, and the solution is dried at 60°C after cleaning.

[0015] Preferably, the method further includes the steps of assembling a medical foam backing, coating with silver chloride conductive hydrogel, covering with release paper, and die-cutting and packaging on the back of the integrated ECG electrode chip.

[0016] An electrocardiogram electrode, characterized in that it comprises: Medical foam backing; conductive hydrogel coated on the backing; and the aforementioned integrated ECG electrode chip, wherein the electrode chip is fixed to the backing by pressing, and the silver chloride enrichment layer on its surface is in contact with the conductive hydrogel.

[0017] The technical effects and advantages of this invention are as follows: 1. In this invention, inexpensive carbon black is used to replace most of the precious metal silver (although the silver layer in traditional copper-plated silver buckles is thin, the processing cost is high; in this application, the amount of AgCl used is small, and there is no copper or silver layer), which can reduce the raw material cost by more than 30%. At the same time, since the metal parts, riveting, electroplating and other processes are eliminated, the overall manufacturing cost is reduced even more significantly.

[0018] 2. One-piece injection molding avoids the risk of metal fasteners loosening or falling off. The filler activation process ensures the uniformity of resistance values ​​within and between batches.

[0019] 3. The entire production process requires no electroplating and no use of toxic chemicals such as cyanide. All processes can be implemented using standard plastic processing equipment and automated production lines, offering a wide technological window and easy implementation.

[0020] 4. Electrode chips of different shapes, sizes and snap-fit ​​structures can be easily designed using injection molds to adapt to different lead wire interfaces. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the integrated ECG electrode chip provided in the embodiments of this application.

[0022] In the diagram: 1. Substrate; 2. Female buckle; 3. Backing; 4. Conductive hydrogel. Detailed Implementation

[0023] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. The embodiments of the present invention are given for illustrative and descriptive purposes only, and are not intended to be exhaustive or to limit the invention to the forms disclosed. Many modifications and variations will be apparent to those skilled in the art. The embodiments were chosen and described to better illustrate the principles and practical application of the invention, and to enable those skilled in the art to understand the invention and design various embodiments with various modifications suitable for a particular purpose. Please see Figure 1 As shown, this embodiment provides an integrated ECG electrode chip, which is integrally molded from conductive composite material using an injection molding process. It includes a substrate 1 and a lead snap-fit ​​female 2 integrated into the substrate. In other words, the entire electrode chip (including the snap-fit ​​structure connected to the lead wires and the chassis in contact with the gel) is a single injection-molded part, requiring no subsequent riveting of any metal parts.

[0024] The raw material composition of conductive composite materials, by weight percentage, includes: Medical-grade ABS resin 62%–72%; Conductive carbon black 20%–23%; Silver chloride powder 5%–13%; And 1% to 3% of additives.

[0025] Among them, the additives include at least coupling agents, lubricants and antioxidants.

[0026] Furthermore, the surface of the electrode chip is enriched with silver chloride through acid activation treatment.

[0027] In this invention, medical-grade ABS (acrylonitrile-butadiene-styrene copolymer) is used as the matrix resin, providing excellent mechanical strength, toughness, and injection molding processability, while meeting medical biocompatibility requirements. Conductive carbon black (preferably acetylene black) forms a percolation conductive network in the ABS matrix, providing low bulk resistance for the electrodes.

[0028] Silver chloride (AgCl) is a key functional filler, and its role is as follows: 1) In the acid activation step after injection molding, the AgCl particles on the surface will undergo micro-reaction with the acid to form a rough surface rich in AgCl, which provides a stable half-cell potential for subsequent contact with the conductive hydrogel, thereby effectively reducing the polarization voltage and eliminating baseline drift. 2) The internal AgCl acts as a polarization buffer, further stabilizing the electrochemical interface.

[0029] The inventors discovered that controlling the addition of AgCl within the range of 5% to 13% effectively achieves depolarization while preventing severe sedimentation during injection molding due to the high density of AgCl (approximately 5 times that of ABS), thus ensuring product consistency. Coupling agents (such as silane coupling agents) in the additive system significantly improve the compatibility between inorganic fillers (carbon black, AgCl) and organic ABS resin, preventing agglomeration; lubricants (such as EVA wax) improve the flowability of the high-filler system, ensuring smooth injection molding; and antioxidants prevent polymer degradation during high-temperature processing.

[0030] This invention provides a method for preparing the above-mentioned integrated electrocardiogram electrode chip.

[0031] The method includes the following steps: S1. Raw material pretreatment: The medical-grade ABS resin is dried to reduce its moisture content to less than 0.1%; conductive carbon black, silver chloride powder and coupling agent are mixed and activated in a high-speed mixer to obtain the modified filler. S2, Premix: The dried medical-grade ABS resin, modified filler and remaining additives are mixed to obtain a premix; S3. Granulation: The premixed material is fed into a twin-screw extruder for melt blending, extrusion, cooling, pelletizing and drying to obtain conductive composite material particles; S4. Injection Molding: The conductive composite material particles are added to the injection molding machine and integrally injection molded through the mold to obtain the electrode chip blank containing the lead buckle female buckle; S5. Surface activation: The electrode chip blank is immersed in acid solution to enrich its surface with silver chloride, and then cleaned and dried to obtain an integrated ECG electrode chip.

[0032] The preparation method of this invention has the following key innovations: Filler activation pretreatment: Adding coupling agent and a small amount of solvent (such as ethanol) during high-speed mixing to modify the surface of carbon black and AgCl is the core step to ensure the nanoscale dispersion of inorganic fillers in ABS, avoiding problems such as uneven conductive network and large product impedance dispersion caused by filler agglomeration.

[0033] Integrated injection molding: Conductive composite material particles are directly injection molded into complete electrode chips with snap-fit ​​structures, completely eliminating all subsequent processes such as metal buckle stamping, electroplating, injection molding base, and riveting in traditional processes, greatly reducing production costs and process complexity.

[0034] Acid surface activation: This is an ingenious chemical treatment step. The injection-molded chip contains uniformly distributed AgCl particles. Short-term immersion in dilute hydrochloric acid causes slight dissolution and recrystallization of the AgCl on the chip surface, or surface roughening, increasing the effective concentration of AgCl at the contact interface. This may be accompanied by trace amounts of silver reduction, forming an Ag / AgCl mixed interface with extremely stable and low-noise half-cell potential characteristics. Compared to directly coating with AgCl slurry, the activation method of this invention has extremely strong adhesion, no risk of detachment, and almost no additional material cost.

[0035] The present invention provides an electrocardiogram electrode comprising the above-described integrated electrocardiogram electrode chip.

[0036] The ECG electrode includes: a medical foam backing 3; a conductive hydrogel coated on the backing 4; and an integrated ECG electrode chip as described above. The electrode chip is pressed and fixed onto the backing using automated equipment, and its acid-activated, AgCl-rich surface is in close contact with the conductive hydrogel to form a stable electrochemical system.

[0037] In one specific embodiment, the raw material information used is as follows: Medical-grade ABS resin: purchased from SABIC, grade MG47, high impact resistance, no exudation, and meets ISO 10993 biocompatibility standard.

[0038] High-purity conductive acetylene carbon black: average particle size 40nm, specific surface area approximately 70 m² / g, purity over 99.5%.

[0039] Micron-sized silver chloride (AgCl) powder: pharmaceutical grade, purity ≥99.8%, D50 3-5μm.

[0040] Silane coupling agent: KH550 (γ-aminopropyltriethoxysilane).

[0041] EVA lubricant: VA content 18%, melt index 150.

[0042] Antioxidant: Hindered phenolic antioxidant 1010.

[0043] Main equipment: High-speed mixer (speed 0-1500rpm, with heating function) Twin-screw extruder (screw diameter 35mm, length-to-diameter ratio L / D=40) Injection molding machine (clamping force 100 tons) AC impedance tester and polarization voltage tester (compliant with YY / T0196 standard) Example 1 (Mature, Mass-Produced Model) Formula (by weight percentage): Medical-grade ABS: 67% Conductive carbon black: 22% Silver chloride powder: 9% Silane coupling agent KH550: 0.6% EVA lubricant: 1.0% Antioxidant 1010: 0.4% Total: 100% Preparation process: (1) Raw material pretreatment: ABS drying: Place the ABS granules in an 80℃ hot air circulating oven and dry for 4 hours. Use a moisture analyzer to test the moisture content, which should be less than 0.1%.

[0044] Filler activation: The formulated amounts of conductive carbon black and AgCl powder are added to a high-speed mixer, along with silane coupling agent KH550, and a small amount of anhydrous ethanol (approximately 5% of the powder weight, to be evaporated later) is sprayed on. The mixer is turned on and heated to 110°C, then stirred at 1100 rpm for 25 minutes. During this time, the ethanol completely evaporates, and the powder surface is fully modified, resulting in a fluffy, non-agglomerated state.

[0045] (2) Premixed: The dried ABS granules, activated mixed filler, EVA lubricant and antioxidant 1010 are put into a low-speed mixer (or the high-speed mixer mentioned above is still used, but the speed is reduced), and mixed at 300 rpm for 15 minutes at 60°C to make the components initially dispersed evenly, so as to obtain a premix.

[0046] (3) Granulation: The premixed material is added to the twin-screw extruder via a metering feeder. The extruder temperatures are set as follows: Zone 1 (feeding section) 210℃, Zone 2 (melting section) 225℃, Zone 3 (mixing section) 232℃, and die head temperature 230℃. The screw speed is set to 300 rpm. After melting and high-intensity shearing mixing within the barrel, the material is extruded from the die head into strips with a diameter of 2-3 mm. The strips are cooled in a water bath, dried by an air dryer, and then fed into a pelletizer to be cut into cylindrical granules. The resulting granules are dried again at 80℃ for 2 hours to obtain conductive ABS particles, which are then sealed in moisture-proof aluminum foil bags for storage.

[0047] (4) Injection molding: The conductive particles are added to the injection molding machine hopper. A specially designed two-plate mold is used, with the mold cavity simultaneously forming the base (15mm in diameter) of the electrode chip and its integrated female snap-fit ​​(standard 4mm snap-fit ​​structure). Injection molding process parameters: mold temperature is controlled at 80℃ using a mold temperature controller; barrel temperature is set to 220℃ (nozzle), 225℃ (middle section), and 230℃ (rear section). Injection pressure is 85 bar, holding pressure is 70 bar, holding time is 3 seconds, and cooling time is 12 seconds. After mold opening, a robotic arm removes the complete integrated electrode chip blank. The blank has a smooth surface, clear snap-fit ​​structure, and no burrs or missing material. The demolded blank is placed on a turnover tray and left to stand naturally at room temperature (25±5℃) for 24 hours to fully release the internal stress generated by injection molding and prevent subsequent deformation.

[0048] (5) Surface activation: Prepare an acid-resistant bath and fill it with a 5% (volume fraction) dilute hydrochloric acid solution. Immerse the settled electrode chip preform completely in the acid solution for 3 minutes at room temperature (25℃). Stir gently during this time. After immersion, remove the chip and immediately rinse it three times with running deionized water to remove any residual acid. Finally, place the chip in a 60℃ hot air oven to dry for 1 hour to obtain the final integrated ECG electrode chip. The chip surface exhibits a slightly rough, light gray color (a slight variation from the untreated black), which is the active layer enriched with silver chloride.

[0049] (6) ECG electrode assembly (back-end process): Using an automated assembly line, the electrode chips are pressed onto a medical foam backing pre-coated with AgCl conductive hydrogel, then covered with PET release paper, and cut into the required electrode sheet shape using a die-cutting machine. Finally, they are packaged in breathable aluminum foil bags to complete the production of the entire ECG electrode.

[0050] 3. Performance Testing: The tests were conducted according to the YY / T 0196-2005 standard for electrocardiogram monitoring electrodes. Standard test fixtures were used in an environment with a temperature of 25℃ and a relative humidity of 60%.

[0051] AC impedance (10Hz): 10 samples were tested, with an average value of 2.1kΩ and a maximum value of 2.4kΩ, all ≤3kΩ standard. The small fluctuation range indicates a uniform conductive network.

[0052] DC offset voltage (polarization voltage): 10 samples were tested, with an average value of 85mV and a maximum value of 92mV, which is far better than the standard of ≤100mV.

[0053] Composite misalignment instability: all samples were less than 0.1 mV, and the baseline was stable.

[0054] Appearance and structure: The clips and leads fit securely without any looseness. There is no precipitation or corrosion on the contact surface between the chip and the gel.

[0055] Example 2 (Low-cost and economical) 1. Formula (by weight percentage): Medical-grade ABS: 72% Conductive carbon black: 21% Silver chloride powder: 5% Additives (same proportions as in Example 1): 2% (KH550 0.6%, EVA 1.0%, 1010 0.4%) Total: 100% 2. Preparation process: The process is basically the same as in Example 1, except that during the injection molding stage, due to its slightly lower carbon black content (21%) and slightly better melt flow, the injection pressure is reduced to 70 bar, while other parameters remain unchanged. The surface activation process remains the same.

[0056] 3. Performance Testing: AC impedance (10Hz): average value 2.8kΩ, maximum value 3.0kΩ, critically compliant with standards. Some samples have slightly higher impedance because the carbon black content is near the critical threshold (20%).

[0057] DC offset voltage (polarization voltage): The average value is 110mV, with some samples exceeding the upper limit of the standard of 100mV. This indicates that when the AgCl content is reduced to 5%, the depolarization ability is weakened, which may not be suitable for high-precision electrocardiographs, but can be used for general bedside monitoring (in situations where the polarization voltage requirement is slightly more lenient).

[0058] Cost analysis: Compared with Example 1, the raw material cost was reduced by about 8%, especially the amount of AgCl used was reduced by nearly half.

[0059] Example 3 (High-precision medical version) 1. Formula (by weight percentage): Medical-grade ABS: 62% Conductive carbon black: 23% Silver chloride powder: 13% Additives (same proportions as in Example 1): 2% Total: 100% 2. Preparation process: The process is essentially the same as in Example 1, but it should be noted that the melt viscosity increases due to the higher total filler content (23% carbon black + 13% AgCl = 36%). To improve dispersion and mold filling, the following adjustments are made: During the filler activation stage, the amount of coupling agent KH550 is slightly increased to 0.8% (adjusted from the additive ratio, keeping ABS at 62% and the total amount of additives controlled at around 2.2%, or slightly deducted from ABS; specifically, in this embodiment, the formula is slightly adjusted as follows: ABS 61.8%, other components unchanged, and additives 2.2%).

[0060] During twin-screw extrusion granulation, the screw speed is increased to 350 rpm to enhance the shearing and mixing effect.

[0061] During injection molding, the barrel temperature is increased to 235℃ (rear section), 230℃ (middle section), and 225℃ (nozzle), the mold temperature is increased to 85℃, and the injection pressure is increased to 95 bar.

[0062] The surface activation time is extended to 5 minutes.

[0063] 3. Performance Testing: AC impedance (10Hz): Average value is 1.5kΩ, maximum value is 1.8kΩ, which is very low and the conductive network is well-developed.

[0064] DC offset voltage (polarization voltage): average value is 45mV, maximum value is 52mV, which is far better than the standard and reaches or even exceeds the performance level of pure silver silver chloride electrode.

[0065] Signal quality: Actual measurements were performed on a diagnostic-grade electrocardiograph. The P wave, QRS wave, and T wave were clear, and the baseline showed almost no drift, meeting the requirements for clinical diagnosis.

[0066] Risk monitoring: In this embodiment, the AgCl content is close to the upper limit of 15%, which places higher demands on the injection molding process control. During production, screw speed and back pressure must be strictly controlled to prevent sedimentation due to excessive AgCl density. Simultaneously, random checks on the density consistency of the finished chips need to be increased. After process optimization, batch consistency in mass production was good, and no brittleness was observed.

[0067] Comparative Example 1 (no silver chloride, pure conductive plastic) Formulation and process: Basically the same as in Example 1, but without the addition of AgCl powder, the ABS content is increased to 76%, carbon black is maintained at 22%, and additives are 2%. The surface activation step is omitted or simply water treatment is performed.

[0068] Performance testing: AC impedance (10Hz): Average value is 1.9kΩ, which is acceptable.

[0069] DC offset voltage (polarization voltage): The average value is as high as 320mV, far exceeding the standard. During simulated ECG signal testing, severe baseline drift and low-frequency noise occur, making the signal unrecognizable.

[0070] Conclusion: Conductive carbon black alone cannot provide a stable electrode-electrolyte interface, lacks depolarization capability, and cannot be used for ECG signal acquisition.

[0071] Comparative Example 2 (no surface activation, no AgCl enrichment) Formulation and process: The formulation is exactly the same as in Example 1 (9% AgCl). However, the "surface activation" step is omitted, that is, after injection molding and standing, no dilute hydrochloric acid soaking or subsequent treatment is performed, and assembly and testing are carried out directly.

[0072] Performance testing: AC impedance (10Hz): Average value is 2.3kΩ, which is acceptable.

[0073] DC offset voltage (polarization voltage): The average value is 185mV, which is unacceptable. Although it is better than Comparative Example 1, it is still far above the standard requirement.

[0074] Analysis: After injection molding, although AgCl particles are present both inside and on the surface of the chip, the vast majority of AgCl is encapsulated or partially encapsulated by the ABS matrix, failing to form an effective, large-area Ag / AgCl electrochemical interface with the conductive hydrogel. Acid activation treatment exposes and enriches the surface AgCl, which is key to its depolarization function.

[0075] Comparative Example 3 (Traditional copper-plated silver button electrode) Solution: Commercially available disposable ECG electrodes conforming to YY / T0196 standard are used. The chip is an independent copper-plated silver female clip that is fixed to the ABS plastic chassis by riveting.

[0076] Performance testing: AC impedance: average 1.2kΩ, polarization voltage: average 40mV, excellent performance.

[0077] Cost analysis: Based on disassembly and BOM estimation, the material cost of a single electrode chip (copper, silver, electroplating, riveting) is approximately three times that of Embodiment 1 of this invention. Furthermore, the production process involves numerous steps and a long cycle time.

[0078] Example 4: Optimization experiments of different auxiliary agent systems and process parameters To verify the wide adaptability of the technical solution of this invention, a series of orthogonal experiments were conducted, mainly to investigate the effects of coupling agent type, acid type / concentration / time of acid activation on the final electrode polarization voltage.

[0079] 4.1 Comparison of Coupling Agents The titanate coupling agent (NDZ-101) was used instead of KH550, otherwise the same as in Example 1. Results: The average polarization voltage increased to 105mV, slightly exceeding the standard, and the current fluctuated significantly during granulation, indicating that the titanate was not as effective as KH550 in improving the compatibility of carbon black / AgCl with ABS. The choice of coupling agent is crucial for dispersion.

[0080] 4.2 Types and concentrations of activating acids The 10% dilute hydrochloric acid was used instead of the 5% dilute hydrochloric acid, and the soaking time was 3 minutes. Result: The chip surface showed slight whitening and powdering. Excessive AgCl dissolution caused a local increase in the surface impedance of the chip, with the average AC impedance rising to 3.5kΩ, which is unacceptable.

[0081] Replacing 5% dilute hydrochloric acid with 5% dilute sulfuric acid, while keeping other parameters unchanged, resulted in an average polarization voltage increase to 130 mV, which was less effective than with hydrochloric acid. This may be related to the specific adsorption of chloride ions; hydrochloric acid provides a chloride ion environment, which is more conducive to the formation of a stable Ag / AgCl interface.

[0082] 4.3 Optimization of Activation Time Based on Example 1, the activation time was shortened to 1 minute. Result: The average polarization voltage was 145mV, indicating insufficient effect.

[0083] The activation time was extended to 10 minutes. Results: The polarization voltage decreased to 65mV, resulting in better performance; however, slight corrosion pits appeared on the chip surface, long-term reliability needs further verification, and production cycle time was increased. 3 minutes proved to be the optimal balance between efficiency and performance.

[0084] Large-scale production stability verification Based on the formulation and process of Example 1, three batches of 100,000 pieces each were produced in a medical device factory with a Class 100,000 cleanroom.

[0085] Process monitoring: The current fluctuation of the twin-screw extruder is within ±2A, indicating stable feeding and melting. The injection molding yield reaches 99.2%, with the main defects being very rare instances of material shortage or flash.

[0086] Product sampling inspection: 100 pieces were randomly selected from each batch for performance testing. The coefficient of variation (CV) of AC impedance within the batch was 3.5%, and the CV between batches was 4.1%, indicating excellent product consistency. All sampled AC impedance (2.0-2.4kΩ) and polarization voltage (78-96mV) met the standards.

[0087] Biocompatibility: The finished electrode chips were sent to a nationally accredited medical device testing center for testing according to the GB / T16886 series standards. Results: The cytotoxicity rating was Grade 1 (qualified), with no skin sensitization reaction and extremely mild skin irritation (irritation index < 0.5). This indicates that all raw materials and processes meet medical requirements.

[0088] Analysis of the comprehensive advantages of the present invention Based on the above embodiments and comparative examples, the technical solution of "ABS + carbon black + AgCl" integrated injection molding combined with acid activation process proposed in this invention successfully achieves low-cost, high-performance manufacturing of ECG electrode chips. Its technological breakthrough lies in: Microstructure design: A multi-level composite structure was formed, consisting of "ABS matrix (structural framework) + carbon black network (conductive pathway) + embedded AgCl (polarization buffer) + surface enriched Ag / AgCl (electrochemical interface)". This structure was spontaneously formed in a single injection molding and simple chemical treatment, demonstrating great ingenuity in the process.

[0089] This invention resolves a key contradiction: Traditionally, conductive plastics are considered unsuitable for precision electrocardiogram (ECG) measurements due to their inability to form a stable half-cell potential. By introducing an appropriate amount of AgCl and using acid activation to enrich it on the surface, this invention cleverly resolves the conflict between conductivity and low polarization voltage. The amount of AgCl used is precisely controlled within a range (5%–13%) that effectively depolarizes without causing processing problems due to excessive density.

[0090] This revolutionized the traditional manufacturing model, shifting from "multi-component assembly" to "single-material functional integration"—a significant transformation in manufacturing philosophy. This not only reduced costs but, more importantly, simplified the supply chain and improved product consistency and reliability.

[0091] Therefore, the electrode chip and its preparation method protected by this invention provide a new and more competitive technical path for the ECG electrode industry, and have extremely high industrial application value.

[0092] Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art and related fields based on the embodiments of the present invention without inventive effort should fall within the scope of protection of the present invention. Structures, devices, and operating methods not specifically described and explained in the present invention, unless otherwise specified or limited, shall be implemented according to conventional means in the art.

Claims

1. An integrated electrocardiogram electrode chip, characterized in that, Includes a substrate and a lead snap female integrated into the substrate; The raw material composition of the conductive composite material includes, by weight percentage: Medical-grade ABS resin 62%–72%; Conductive carbon black 20%–23%; Silver chloride powder 5%–13%; And 1%–3% of additives; The additives include at least coupling agents, lubricants, and antioxidants; The surface of the electrode chip is formed with a silver chloride layer enriched by acid activation treatment.

2. The integrated ECG electrode chip according to claim 1, characterized in that, The raw material composition of the conductive composite material is as follows, by weight percentage: Medical-grade ABS resin 67%; Conductive carbon black 22%; 9% silver chloride powder; Coupling agent 0.6%; Lubricant 1.0%; Antioxidant 0.4%.

3. The integrated ECG electrode chip according to claim 1, characterized in that, The conductive carbon black is acetylene black with a particle size of 30-50 nm. The silver chloride powder has a purity of ≥99.5% and a particle size in the micrometer range.

4. A method for fabricating an integrated electrocardiogram electrode chip according to any one of claims 1-3, characterized in that, Includes the following steps: S1. Raw material pretreatment: The medical-grade ABS resin is dried to reduce its moisture content to less than 0.1%; the conductive carbon black, silver chloride powder and coupling agent are mixed and activated in a high-speed mixer to obtain the modified filler; S2, Premix: The dried medical-grade ABS resin, modified filler and remaining additives are mixed to obtain a premix; S3. Granulation: The premixed material is fed into a twin-screw extruder for melt blending, extrusion, cooling, pelletizing and drying to obtain conductive composite material particles; S4. Injection molding: The conductive composite material particles are added to an injection molding machine and integrally injection molded through a mold to obtain an electrode chip blank containing a lead-connecting snap-fit ​​female buckle; S5. Surface activation: The electrode chip preform is immersed in acid solution to enrich its surface with silver chloride, and then cleaned and dried to obtain the integrated ECG electrode chip.

5. The preparation method according to claim 4, characterized in that, In step S1, the drying conditions for the ABS resin are: drying in an 80°C hot air oven for 4 hours; The specific steps for activating the filler are as follows: conductive carbon black and silver chloride powder are put into a high-speed mixer, silane coupling agent and anhydrous ethanol are added, and the mixture is stirred at high speed for 25 minutes at 110°C to allow the ethanol to evaporate and complete the surface modification of the powder. The premixing step involves mixing at low speed for 15 minutes at 60°C in a mixer.

6. The preparation method according to claim 4, characterized in that, In step S3, the segmented temperature control of the twin-screw extruder is as follows: Zone 1 210℃, Zone 2 225℃, Zone 3 232℃, and Die 230℃, with a screw speed of 300 rpm. After extrusion, the material is water-cooled, stretched, and pelletized, and then dried at 80℃ for 2 hours.

7. The preparation method according to claim 4, characterized in that, In step S4, the injection molding process parameters are as follows: mold preheating temperature 75-85℃, barrel temperature 220-230℃, injection pressure 70-90 bar, holding time 3 seconds, and cooling and setting time 12 seconds; the molded preform is left to stand at room temperature for 24 hours to release internal stress.

8. The preparation method according to claim 4, characterized in that, In step S5, the acid solution is 5% dilute hydrochloric acid, the soaking time is 3 minutes, and after cleaning, it is dried at 60°C.

9. The preparation method according to claim 4, characterized in that, The method also includes the steps of assembling a medical foam backing, coating with silver chloride conductive hydrogel, covering with release paper, and die-cutting and packaging on the back of the integrated ECG electrode chip.

10. An electrocardiogram electrode, characterized in that, include: Medical foam backing; Conductive hydrogel coated on the backing; And the integrated ECG electrode chip as described in any one of claims 1-3, wherein the electrode chip is fixed to the backing by pressing, and the silver chloride enrichment layer on its surface is in contact with the conductive hydrogel.

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