A flexible electrode sensor module and a method of manufacturing the same, integrated circuit system

Abstract

This application relates to the field of flexible electronic sensing technology, and provides a flexible electrode sensor module, including a first encapsulation layer, a silver paste conductive layer, a second encapsulation layer, and a third encapsulation layer stacked sequentially. The silver paste conductive layer is composed of at least two layers of screen-printed and cured silver paste, including a sensing part for contact sensing, a connecting part for signal output, and a connection point region disposed at the end of the connecting part. The second encapsulation layer covers the silver paste conductive layer, and the third encapsulation layer is disposed on the second encapsulation layer. The third encapsulation layer covers the edge of the silver paste conductive layer in the region corresponding to the sensing part and the connection point, and covers the surface of the silver paste conductive layer in the region corresponding to the connecting part. Based on this, conductivity can be improved while mechanical properties and signal stability are also improved.

Description

Technical Field

[0001] This invention relates to the field of flexible electronic sensing technology, specifically to a flexible electrode sensor module and its fabrication method, as well as an integrated circuit system. Background Technology

[0002] With the increasing popularity of wearable health monitoring devices, the demand for flexible dry electrodes that can be worn comfortably for extended periods and provide stable signals is becoming increasingly urgent. In the preparation of electrodes using conductive silver paste, the silver paste layer is a single brittle conductive film. Under repeated bending or tensile stress, it is prone to micro-cracks or even fracture due to stress concentration, leading to a decrease in conductivity. Furthermore, the electrode module has different encapsulation requirements for the sensing area, connection part, and connection point area. Current encapsulation technology uses overall thick-layer coating, which reduces the flexibility and precision of the motor module, or local dispensing, resulting in insufficient protection and poor process consistency. This leads to susceptibility to motion artifact interference and signal instability.

[0003] Therefore, this application studies a flexible electrode sensor module that can improve conductivity while also improving mechanical properties and signal stability. Summary of the Invention

[0004] In order to improve conductivity while also improving mechanical properties and signal stability.

[0005] On the one hand, the flexible electrode sensor module provided in this application adopts the following technical solution:

[0006] A flexible electrode sensor module includes a first encapsulation layer, a silver paste conductive layer, a second encapsulation layer, and a third encapsulation layer stacked sequentially. The silver paste conductive layer is composed of at least two layers of screen-printed and cured silver paste, including a sensing part for contact sensing, a connecting part for signal output, and a connection point region disposed at the end of the connecting part. The second encapsulation layer covers the silver paste conductive layer, and the third encapsulation layer is disposed on the second encapsulation layer. The third encapsulation layer covers the edge of the silver paste conductive layer in the region corresponding to the sensing part and the connection point, and covers the surface of the silver paste conductive layer in the region corresponding to the connection part.

[0007] By adopting the above technical solution, the third encapsulation layer is the side that contacts the human body, and the silver paste conductive layer is a composite structure composed of at least two layers of screen-printed and cured silver paste. The interlayer interfaces inside can prevent vertical penetration of cracks and also support each other, enhancing the overall toughness and crack propagation resistance of the silver paste layer, improving the mechanical properties of the electrode, and ensuring conductivity. At the same time, by setting the third encapsulation layer and performing precise and differentiated configuration of edge wrapping of the sensing part, surface coverage of the connection part, and edge wrapping of the connection point area, targeted protection of different functional areas is achieved. This ensures both the effective area of ​​signal acquisition and connection reliability, while effectively sealing the edges and preventing interference introduction, thereby synergistically improving the mechanical properties of the electrode and signal stability.

[0008] Optionally, it also includes a first adhesive layer and a support layer, wherein the first adhesive layer is disposed on the side of the first encapsulation layer opposite to the silver paste conductive layer, and the support layer is disposed on the side of the first adhesive layer opposite to the first encapsulation layer.

[0009] By adopting the above technical solution, the support layer, as a base, helps maintain the overall shape of the module and disperse external stress, while the adhesive layer ensures a firm bond between the upper functional structure and the lower support. The stress transmission path is optimized from the bottom of the structure, providing a foundation for improving the overall mechanical performance.

[0010] Optionally, the material of the support layer is thermoplastic polyurethane.

[0011] By adopting the above technical solution, external stress can be effectively absorbed and buffered, and it can be evenly distributed to avoid excessive stress concentration on the upper silver paste conductive layer. This significantly enhances the module's bending resistance and fatigue resistance, and further improves its mechanical properties.

[0012] Optionally, the first adhesive layer is a composite structure, including a high-resilience thermoplastic polyurethane layer in contact with the first encapsulation layer and a hot-melt thermoplastic polyurethane layer in contact with the support layer.

[0013] By adopting the above technical solution, the high-resilience thermoplastic polyurethane layer, as a stress buffer layer, further optimizes the modulus transition between the silver paste conductive layer and the underlying structure, effectively alleviating the interface stress concentration during dynamic bending; the hot-melt thermoplastic polyurethane layer provides strong and uniform adhesion to the support layer, enhances the interfacial bonding strength and toughness between key layers, effectively suppresses the risk of interlayer delamination and cracking of the silver paste conductive layer due to interface failure, and further improves mechanical properties.

[0014] Optionally, the cured metallic silver content in the silver paste conductive layer is 60% to 68%.

[0015] By adopting the above technical solution, a high-density, continuous conductive network of conductive phase (silver particles) is formed, thereby ensuring the low resistance and high conductivity of the electrode.

[0016] Optionally, the second encapsulation layer includes a carbon paste layer and a polyurethane resin layer stacked sequentially.

[0017] By adopting the above technical solution, the carbon paste layer has high resistivity, which can balance the electric field distribution on the surface of the silver paste layer, dissipate static charge, suppress the introduction of electromagnetic interference, and help improve signal stability; the polyurethane resin layer provides excellent insulation and flexibility. The combination of the two makes the second encapsulation layer not only play an insulating protection role, but also become a functional intermediate layer. While improving signal quality and stability, its elastic properties also help buffer stress.

[0018] On the other hand, the method for fabricating a flexible electrode sensor module provided in this application adopts the following technical solution: A method for fabricating a flexible electrode sensor module includes the following steps: S1: Forming a first encapsulation layer on the substrate; S2: Silver paste is screen-printed onto the first encapsulation layer at least twice and then baked and cured successively to form a silver paste conductive layer; S3: A second encapsulation layer is formed on the silver paste conductive layer; S4: A third encapsulation layer is formed on the second encapsulation layer, and the third encapsulation layer covers only the edges of the sensing area and the connection point area of ​​the silver paste conductive layer, and covers the surface of the connection point.

[0019] Optionally, in step S2, the baking and curing conditions after each screen printing of silver paste are: 10-20 minutes at a temperature of 120℃-140℃.

[0020] Optionally, in step S3, the step of forming the second encapsulation layer includes: first printing and curing a carbon paste layer on the silver paste conductive layer, and then printing and curing a polyurethane resin layer on the carbon paste layer.

[0021] In summary, this application includes the following beneficial technical effects: 1. The first encapsulation layer is the side that contacts the human body. The silver paste conductive layer is a composite structure composed of at least two layers of screen-printed and cured silver paste. The interlayer interfaces inside can prevent vertical penetration of cracks and also support each other, enhancing the overall toughness and crack propagation resistance of the silver paste layer, improving the mechanical properties of the electrode, and ensuring conductivity. At the same time, by setting a third encapsulation layer and performing precise and differentiated configuration of edge wrapping of the sensing part, surface coverage of the connection part, and edge wrapping of the connection point area, targeted protection of different functional areas is achieved. This ensures both the effective area of ​​signal acquisition and connection reliability, and effectively seals the edges and prevents interference introduction, thereby synergistically improving the mechanical properties of the electrode and signal stability. 2. The support layer, as a base, helps maintain the overall shape of the module and disperse external stress, while the adhesive layer ensures a firm bond between the upper functional structure and the lower support, optimizing the stress transmission path from the bottom of the structure and providing a foundation for improving the overall mechanical performance; 3. The carbon paste layer of the second encapsulation layer has high resistivity, which can balance the electric field distribution on the surface of the silver paste layer, dissipate static charge, suppress the introduction of electromagnetic interference, and help improve signal stability; the polyurethane resin layer provides excellent insulation and flexibility. The combination of the two makes the second encapsulation layer not only play an insulating protection role, but also become a functional intermediate layer. While improving signal quality and stability, its elastic properties also help buffer stress. Attached Figure Description

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

[0023] In the diagram: Figure 1 This is a schematic diagram of different layer structures in the flexible electrode sensor module of this application embodiment; Figure 2 This is a schematic diagram showing the corresponding shapes of the third encapsulation layer and the silver paste conductive layer in the flexible electrode sensor module of this application embodiment; Figure 3 This is a schematic diagram of the silver paste conductive layer forming process in the flexible electrode sensor module of this application. Reference numerals: 1. First encapsulation layer; 2. Second encapsulation layer; 3. Third encapsulation layer; 4. First adhesive layer; 5. Support layer; 6. Structural layer; 7. Second adhesive layer; 8. Silver paste conductive layer; 81. Sensing part; 82. Connecting part; 83. Connecting point area. Detailed Implementation

[0024] The following is in conjunction with the appendix Figure 1-3 This application will be described in further detail.

[0025] This application discloses a flexible electrode sensor module. (Refer to...) Figure 1 The flexible electrode sensor module includes a first encapsulation layer 1, a silver paste conductive layer 8, a second encapsulation layer 2, and a third encapsulation layer 3 stacked in sequence; the third encapsulation layer 3 is the side that contacts the human body, and the first encapsulation layer 1 is used to isolate the device from the bottom substrate to prevent unnecessary signals from entering the acquisition area and the connection part 82.

[0026] The silver paste conductive layer 8 consists of at least two layers of screen-printed and cured silver paste, including a sensing part 81 for contact sensing, a connecting part 82 for signal output, and a connection point region 83 disposed at the end of the connecting part 82. The interlayer interfaces within the composite structure can prevent vertical crack penetration and also provide mutual support, enhancing the overall toughness and crack propagation resistance of the silver paste layer, improving the mechanical properties of the electrode, and ensuring conductivity.

[0027] Reference Figure 2 The second encapsulation layer 2 covers the silver paste conductive layer 8, and the third encapsulation layer 3 is disposed on the second encapsulation layer 2. In the area corresponding to the sensing part 81 and the connection point, the third encapsulation layer 3 covers the edge of the silver paste conductive layer 8; in the area corresponding to the connection part 82, it covers the surface of the silver paste conductive layer 8. This allows for precise and differentiated configuration of different areas, achieving targeted protection for different functional zones. It ensures both the effective area for signal acquisition and connection reliability, while effectively sealing the edges and preventing interference introduction, thereby synergistically improving the mechanical performance and signal stability of the electrodes. The third encapsulation layer 3 can be composed of a single layer of hot-melt material or a hot-melt material covered with other insulating materials.

[0028] In some embodiments, the system further includes a first adhesive layer 4 and a support layer 5. The first adhesive layer 4 is disposed on the side of the first encapsulation layer 1 opposite to the silver paste conductive layer 8, and the support layer 5 is disposed on the side of the first adhesive layer 4 opposite to the first encapsulation layer 1. A structural layer 6, such as PET, fabric, or a structural component, may be disposed on the side of the support layer 5 opposite to the first adhesive layer 4. A second adhesive layer 7, such as a hot melt adhesive, solvent-based coating, or water-based coating, may also be disposed on the side of the structural layer 6 opposite to the support layer 5. The support layer 5 provides a certain elastic tension to the shape between the silver paste conductive layer 8 and the structural layer 6 or the adhesion surface. When the support layer 5 itself has a certain degree of single-sided or double-sided adhesion under specific conditions, it can replace part of the function of the upper and lower adhesive layers.

[0029] In some embodiments, the material of the support layer 5 is thermoplastic polyurethane.

[0030] In some embodiments, the first adhesive layer 4 is a composite structure, comprising a high-resilience thermoplastic polyurethane layer in contact with the first encapsulation layer 1 and a hot-melt thermoplastic polyurethane layer in contact with the support layer 5. The first adhesive layer 4 is used to fix the first encapsulation layer 1 and the support layer 5, and to provide partial tension of the support layer 5 to various localities of the additional conductive layer, as well as partial isolation of conductive electrical signals.

[0031] In some embodiments, the cured metallic silver content in the silver paste conductive layer 8 is 60% to 68%.

[0032] In some embodiments, the second encapsulation layer 2 includes a carbon paste layer and a polyurethane resin layer stacked sequentially.

[0033] The implementation principle of a flexible electrode sensor module in this application embodiment is as follows: The first encapsulation layer 1 is the side that contacts the human body, and the silver paste conductive layer 8 is a composite structure composed of at least two layers of screen-printed and cured silver paste. The interlayer interfaces inside can prevent vertical penetration of cracks and can also support each other, enhancing the overall toughness and crack propagation resistance of the silver paste layer, improving the mechanical properties of the electrode, and ensuring conductivity. At the same time, by setting a third encapsulation layer 3 and performing precise and differentiated configuration of edge covering of sensing part 81, surface covering of connecting part 82, and edge covering of connection point area 83, targeted protection of different functional areas is achieved, which not only ensures the effective area of ​​signal acquisition and connection reliability, but also effectively seals the edges and prevents interference introduction, thereby synergistically improving the mechanical properties and signal stability of the electrode.

[0034] This application also discloses a method for fabricating a flexible electrode sensor module. The method for fabricating the flexible electrode sensor module includes the following steps: S1: A first encapsulation layer 1 is formed on the substrate.

[0035] Before step S1, a stress relief pretreatment step is also included, which includes preheating the substrate at 120°C-140°C for 10-20 minutes and then letting it stand at room temperature for at least 10 minutes.

[0036] This embodiment also includes a first adhesive layer 4 and a support layer 5. The first adhesive layer 4 is a composite structure, including a high-resilience thermoplastic polyurethane layer in contact with the first encapsulation layer 1, the thickness of the high-resilience thermoplastic polyurethane layer is 50-75μm, and the resilience is 97%; and a hot-melt thermoplastic polyurethane layer in contact with the support layer 5, the thickness of the hot-melt thermoplastic polyurethane layer is 20-50μm.

[0037] S11: The first encapsulation layer 1 is printed on the corresponding position of the high-resilience thermoplastic polyurethane layer of the first adhesive layer 4 by screen printing, and then cured by low-temperature baking at 130°C for 15 minutes to form a 4-6μm first encapsulation layer 1. The hot-melt thermoplastic polyurethane layer is bonded to the support layer 5.

[0038] Reference Figure 3 S2: Silver paste conductive layer 8 is formed by screen printing silver paste on the first encapsulation layer 1 at least twice and baking and curing it successively.

[0039] In step S2, the baking and curing conditions after each screen-printed silver paste are as follows: 10-20 minutes at 120℃-140℃. Specifically, the first screen-printed layer of silver paste (6-7μm) is baked at 130℃ for 15 minutes to form the first layer of silver paste. Then, a second screen-printed layer of silver paste (6-7μm) is baked at 130℃ for 15 minutes to form the second layer of silver paste. This ensures the uniformity and conductivity of the silver paste electrode, while also ensuring that the density of the silver paste layer gradually increases from the inside out. After the effective components of the outer silver paste are oxidized, the oxidation rate of the effective components inside gradually decreases, and the layer gradually becomes denser, ensuring that the bottom layer (i.e., the first coated silver paste layer) is denser. Figure 3 The first layer of silver paste has high density and is difficult to oxidize. Multiple baking processes create a multi-layered, repeating density distribution pattern of sparse, relatively dense, relatively sparse, and dense layers. This ensures conductivity between layers in the vertical direction, while the overall trend shows that the lower layers become increasingly dense and difficult to oxidize, improving lifespan. Oxidation and doping of the original material at the junction between two layers also protect the next layer. This extends the sensor's lifespan, ensuring that signal changes caused by physiological changes in the sensing area can be detected by the signal acquisition circuit connected to the data connection area with a high signal-to-noise ratio, while also possessing the soft and stretchable properties of textiles.

[0040] S3: A second encapsulation layer 2 is formed on the silver paste conductive layer 8.

[0041] The silver paste conductive layer 8 mainly consists of low-temperature heated and cured silver paste electrodes, forming flexible electrodes. In the paste before curing, approximately 32%-37% of the main functional materials are partially volatile solvents, with a silver content of approximately 50-63%. The remainder consists of elastic resin materials and thermoplastic polyurethane. The elastic resin material provides tensile strength and resilience, while the thermoplastic polyurethane provides adhesion. After low-temperature curing, the silver content reaches 60%-68%, ensuring a low resistivity of <50mΩ / sq / 25μm.

[0042] Specifically, the second encapsulation layer 2 includes a carbon paste layer and a polyurethane resin layer stacked sequentially. In step S3, the step of forming the second encapsulation layer 2 includes: first printing and curing a carbon paste layer on the silver paste conductive layer 8 to form a carbon paste layer, and then printing and curing a polyurethane resin layer on the carbon paste layer to form a polyurethane resin layer.

[0043] S31: Coating is performed using a carbon paste with low conductivity. This paste, with a solids content of 25-35%, has a density of approximately 1.6 g / cm³ and a viscosity of approximately 50 Pa·s. After being cured at a low temperature of 130°C for 15 minutes, a 5 μm carbon paste layer is formed. This achieves stretchability and a pencil hardness of 1H while maintaining a surface resistivity of ≤750,000 milliohms per square square (mΩ / sq). This prevents weak signals from coupling into the conductive layer, which could unnecessarily affect the amplification and filtering of bioelectrical signals.

[0044] A polyurethane resin elastic encapsulation material is coated on top of the carbon paste layer. This paste, with a solid content of 20-25%, has a density of about 1.06 g / cm³ and can achieve a viscosity of about 35 Pa·s at room temperature. After being cured at a low temperature of 130°C for 15 minutes, a 4-5 μm polyurethane resin layer is formed, which is a stretchable insulator with a pencil hardness of 1H. This can prevent external medium and high voltage signals from coupling into the conductive layer under normal conditions, thus avoiding signal instability in the circuit.

[0045] S4: A third encapsulation layer 3 is formed on the second encapsulation layer 2, and the third encapsulation layer 3 only covers the edges of the sensing portion 81 region and the connection point region 83 of the silver paste conductive layer 8, and covers the surface of the connection portion 82. This prevents the uneven surface of the edge gap from contacting the human body or other surfaces to create connections and conductions, resulting in signals and interference beyond the intended performance.

[0046] This application also discloses an integrated circuit system. The integrated circuit system includes the aforementioned flexible electrode sensor module and a signal conditioning circuit electrically connected to the flexible electrode sensor module. When used for collecting EEG information, the flexible electrode module serves as a data electrode, a reference electrode, a right leg drive electrode (DRL) electrode, and a ground electrode. The signal conditioning circuit includes a first-stage amplifier and a second-stage amplifier. Both the reference electrode and the data electrode are connected in series to the same second-stage amplifier with a high common-mode rejection ratio (CMRR) after passing through a first-stage amplifier with a low CMRR. The output of the second-stage amplifier forms a common-mode negative feedback loop with the reference input. Therefore, the effective CMRR can exceed the CMRR values ​​of each stage amplifier. For example, if the first-stage amplifier has a CMRR of 66dB and the second-stage amplifier has a CMRR of 115dB, then the effective CMRR is >115dB.

[0047] The above are exemplary embodiments disclosed in this invention. However, it should be noted that various changes and modifications can be made without departing from the scope of the embodiments of this invention as defined by the claims. The functions, steps, and / or actions of the methods according to the disclosed embodiments described herein do not need to be performed in any particular order. Furthermore, although the elements disclosed in the embodiments of this invention may be described or claimed individually, they may be understood as multiple unless explicitly limited to a singular number.

[0048] It should be understood that, as used herein, the singular form "a" is intended to include the plural form as well, unless the context clearly supports an exception. It should also be understood that, as used herein, "and / or" refers to any and all possible combinations of one or more of the associatedly listed items. The embodiment numbers disclosed above are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0049] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention (including the claims) is limited to these examples. Within the framework of the invention, technical features of the above embodiments or different embodiments can be combined, and many other variations of different aspects of the invention exist, which are not provided in the details for the sake of brevity. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the invention should be included within the protection scope of the invention.

Claims

1. A flexible electrode sensor module, characterized by: The device comprises a first encapsulation layer, a silver paste conductive layer, a second encapsulation layer, and a third encapsulation layer stacked sequentially. The silver paste conductive layer is composed of at least two layers of screen-printed and cured silver paste, including a sensing part for contact sensing, a connection part for signal output, and a connection point area disposed at the end of the connection part. The second encapsulation layer covers the silver paste conductive layer, and the third encapsulation layer is disposed on the second encapsulation layer. The third encapsulation layer covers the edge of the silver paste conductive layer in the region corresponding to the sensing part and the connection point, and covers the surface of the silver paste conductive layer in the region corresponding to the connection part.

2. The flexible electrode sensor module of claim 1, wherein: It also includes a first adhesive layer and a support layer, wherein the first adhesive layer is disposed on the side of the first encapsulation layer opposite to the silver paste conductive layer, and the support layer is disposed on the side of the first adhesive layer opposite to the first encapsulation layer.

3. The flexible electrode sensor module of claim 2, wherein: The material of the support layer is thermoplastic polyurethane.

4. The flexible electrode sensor module of claim 2, wherein: The first adhesive layer is a composite structure, comprising a high-resilience thermoplastic polyurethane layer in contact with the first encapsulation layer and a hot-melt thermoplastic polyurethane layer in contact with the support layer.

5. The flexible electrode sensor module of claim 1, wherein: In the silver paste conductive layer, the mass content of the cured metallic silver is 60% to 68%.

6. The flexible electrode sensor module of claim 1, wherein: The second encapsulation layer comprises a carbon paste layer and a polyurethane resin layer stacked sequentially.

7. A method of manufacturing a flexible electrode sensor module as claimed in any one of claims 1-6, characterized in that: Includes the following steps: S1: Forming a first encapsulation layer on the substrate; S2: Silver paste is screen-printed onto the first encapsulation layer at least twice and then baked and cured successively to form a silver paste conductive layer; S3: A second encapsulation layer is formed on the silver paste conductive layer; S4: A third encapsulation layer is formed on the second encapsulation layer, and the third encapsulation layer covers only the edges of the sensing area and the connection point area of ​​the silver paste conductive layer, and covers the surface of the connection point.

8. The method of claim 7, wherein: In step S2, the baking and curing conditions after each screen printing of silver paste are: 10-20 minutes at a temperature of 120℃-140℃.

9. The method of claim 7, wherein: In step S3, the step of forming the second encapsulation layer includes: first printing and curing a carbon paste layer on the silver paste conductive layer, and then printing and curing a polyurethane resin layer on the carbon paste layer.

10. An integrated circuit system, characterized by: It includes a flexible electrode sensor module as described in any one of claims 1-6, and a signal conditioning circuit electrically connected to the flexible electrode sensor module.

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