A dome microstructure flexible electrode for an ionic capacitive pressure sensor and a method of manufacturing the same, and an ionic capacitive pressure sensor

Abstract

The application provides a dome microstructure flexible electrode for an ionic capacitance pressure sensor and a preparation method thereof, and an ionic capacitance pressure sensor, which comprises a flexible substrate layer, a conductive microstructure layer and a flexible packaging layer; the flexible substrate layer is arranged between the conductive microstructure layer and the flexible packaging layer; the conductive microstructure layer has a dome-shaped protruding microstructure array, which is used for increasing the effective contact area between the conductive microstructure layer and an ionic dielectric layer. The dome-shaped protruding microstructure array is constructed by a negative pressure adsorption forming mode, and the conductive microstructure layer is arranged between two flexible polymer layers, so that the microstructure regulation effect and the electrode structure stability are considered.

Description

Technical Field

[0001] This invention relates to the field of flexible pressure sensor technology, specifically to a dome-shaped microstructure flexible electrode for an ion-capacitive pressure sensor, its fabrication method, and the ion-capacitive pressure sensor itself. Background Technology

[0002] In recent years, with the rapid development of electronic skin, health monitoring, intelligent robots, and wearable electronic devices, flexible pressure sensors have attracted widespread attention due to their advantages such as bendability, stretchability, light weight, and ease of attachment to complex curved surfaces. Compared to piezoresistive and piezoelectric pressure sensors, capacitive pressure sensors offer advantages such as low power consumption, fast response speed, good signal stability, and ease of array integration. Among them, ion-capacitive pressure sensors based on ion-dielectric layers utilize the electrical double-layer capacitance effect formed at the interface between the electrode and the ion-dielectric material to achieve high interface capacitance, thus exhibiting high sensitivity and a low detection limit.

[0003] To further improve the pressure response capability of ion-capacitive pressure sensors, microstructures are typically constructed on the surface of the electrode layer or dielectric layer to increase the effective contact area between the electrode and the ion-dielectric layer. Dome-shaped microstructures, due to their continuous curved surface, smoother contact area change under pressure, and smaller stress concentration, are suitable for use as interface control structures in flexible capacitive sensors.

[0004] Existing microstructure electrodes are commonly fabricated using methods such as magnetron sputtering, thermal evaporation, spraying conductive materials, photolithography replication, or template transfer. While these methods can obtain microstructured surfaces, they often require specialized vacuum coating equipment or complex patterning processes, resulting in high fabrication costs, narrow process windows, and limitations in the fabrication of flexible, large-area, or low-cost devices.

[0005] Furthermore, existing conductive layers are mostly directly attached to the surface of flexible substrates, which are prone to cracking, peeling, or detachment during long-term bending, stretching, and cyclic loading, thus affecting device stability and lifespan. If the bond between the conductive layer and the flexible substrate is weak, the microstructure is also prone to morphological degradation or unstable conductive pathways during repeated pressure. Therefore, it is necessary to provide a flexible electrode with a simple fabrication process, a strong conductive layer bond, and the ability to form a stable dome-shaped microstructure array, as well as its fabrication method. Summary of the Invention

[0006] To address the shortcomings of existing technologies, such as high equipment costs in the fabrication of flexible microstructure electrodes, insufficient bonding between the conductive layer and the flexible substrate, and the susceptibility of the conductive layer to cracking, peeling, or detachment during long-term cyclic loading, this invention provides a dome-shaped flexible microstructure electrode for ion-capacitive pressure sensors, along with its fabrication method and the ion-capacitive pressure sensor itself. The dome-shaped protruding microstructure array is constructed using a negative pressure adsorption molding method, sandwiching the conductive microstructure layer between two layers of flexible polymer, thereby achieving both microstructure control and electrode structural stability.

[0007] The present invention achieves the above-mentioned technical objectives through the following technical means.

[0008] A dome-shaped microstructure flexible electrode for an ion-capacitive pressure sensor includes a flexible substrate layer, a conductive microstructure layer, and a flexible encapsulation layer; the flexible substrate layer is sandwiched between the conductive microstructure layer and the flexible encapsulation layer; the conductive microstructure layer has a dome-shaped array of protruding microstructures to increase the effective contact area between the conductive microstructure layer and the ion-dielectric layer.

[0009] Furthermore, the dome-shaped protrusion microstructure array is formed by causing the flexible substrate layer and the conductive microstructure layer to undergo local deformation together through negative pressure adsorption.

[0010] Furthermore, the flexible substrate layer and the flexible encapsulation layer are prepared using one or more of PDMS, Ecoflex silicone, or polyurethane.

[0011] Furthermore, the conductive microstructure layer is formed using stretchable conductive silver paste.

[0012] An ion-capacitive pressure sensor includes a dome-shaped microstructure flexible electrode, an ion dielectric layer, and a counter electrode; the ion dielectric layer is disposed between the dome-shaped microstructure flexible electrode and the counter electrode, and together with the dome-shaped microstructure flexible electrode, forms a capacitive sensing structure; the array of dome-shaped protruding microstructures of the dome-shaped microstructure flexible electrode faces the ion dielectric layer.

[0013] Furthermore, the ionic dielectric layer is an ionic gel film, which is formed by combining a polymer matrix and an ionic liquid.

[0014] Furthermore, the polymer matrix is ​​PVDF-HFP, the ionic liquid is [EMIM][TFSI], and the mass ratio of PVDF-HFP to [EMIM][TFSI] is 1:2 to 1:4.

[0015] Furthermore, the counter electrode is a flexible planar electrode; the flexible planar electrode is an aluminum foil or a flexible polymer film with a conductive layer coated on its surface.

[0016] Furthermore, the dome-shaped microstructure flexible electrode, the ion dielectric layer, and the counter electrode are stacked sequentially along the thickness direction. One surface of the ion dielectric layer abuts against the top of the dome-shaped protruding microstructure array, and the other surface of the ion dielectric layer is attached to the surface of the counter electrode.

[0017] A method for fabricating the dome-shaped microstructure flexible electrode includes the following steps:

[0018] Fabrication of a flexible substrate layer;

[0019] A stretchable silver paste is spin-coated onto the surface of the flexible substrate to form a conductive layer;

[0020] A flexible substrate with a conductive layer is attached to a template with an array of through holes, with the conductive layer facing the template. A negative pressure is applied to cause the flexible substrate and the conductive layer to deform locally into the through holes, forming an array of dome-shaped protruding microstructures.

[0021] The negative pressure is released and the template is removed. A flexible encapsulation layer is then attached to the flexible substrate layer to obtain a dome-shaped microstructure flexible electrode.

[0022] The beneficial effects of this invention are as follows:

[0023] 1. The dome-shaped microstructure flexible electrode for ion capacitive pressure sensors described in this invention constructs a dome-shaped protruding microstructure array through a negative pressure adsorption molding process. This allows the flexible substrate layer and the conductive layer to undergo local deformation synchronously under negative pressure. This eliminates the need for expensive equipment and complex processes such as magnetron sputtering, thermal evaporation, or photolithography, and can form a regular microstructure array on the surface of a flexible polymer. This significantly reduces the cost and equipment threshold of electrode fabrication. At the same time, it has a wide process window, is easy to operate, and is suitable for mass production.

[0024] 2. The dome-shaped microstructure flexible electrode for an ion-capacitive pressure sensor described in this invention, by setting a conductive microstructure layer on one side of a flexible substrate and setting a flexible encapsulation layer on the other side of the flexible substrate, allows the deformation displacement of the conductive layer to be constrained by the elastic bearing of the flexible substrate and the back support of the flexible encapsulation layer when subjected to external compressive stress. At the same time, the flexible substrate, as an intermediate bearing layer, can buffer and disperse stress concentration at the interface between the conductive layer and the substrate, thereby reducing the risk of crack propagation or interface peeling of the conductive layer during bending, stretching, and repeated compression, and improving the structural stability of the electrode under long-term cyclic use conditions.

[0025] 3. The dome-shaped microstructure flexible electrode for ion-capacitive pressure sensors of the present invention has a dome-shaped array of protruding microstructures in its conductive microstructure layer. Under pressure, the dome shape can form a smooth and continuous change in contact area with the ion dielectric layer. Compared with planar electrodes or microstructure electrodes without a protective layer, it effectively increases the interfacial contact area between the electrode and the ion dielectric layer, enhances the electrical double-layer capacitance effect, and thus improves the pressure response sensitivity and signal change amplitude of the sensor.

[0026] 4. The dome-shaped microstructure flexible electrode fabrication process of the present invention has an array of through holes on a template formed by negative pressure adsorption. The diameter and center distance of the through holes are configured so that each dome-shaped protrusion is independent and does not merge during the forming process, thus ensuring the regularity and uniformity of the microstructure array. At the same time, the template can be fabricated by 3D printing, and the hole diameter, spacing and array area can be flexibly adjusted as needed. It has strong process adaptability and is suitable for fabricating large-area electrodes.

[0027] 5. The ion-capacitive pressure sensor described in this invention exhibits excellent pressure response characteristics under test conditions: a sensitivity of 468.9 kPa within the pressure range of 0~90 kPa. -1 The sensitivity within the pressure range of 90~160 kPa is 273.15 kPa. -1 The response time is approximately 90 ms, and the signal remains stable after 2000 cycles of loading at 200 kPa pressure, indicating that the electrode structure endows the sensor with high sensitivity, fast response speed, and good cycle stability. Attached Figure Description

[0028] 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. The drawings described below are some embodiments of the present invention. For those skilled in the art, it is obvious that other drawings can be obtained from these drawings without creative effort.

[0029] Figure 1 This is a scanning electron microscope image of the cross-section of the dome-shaped microstructure flexible electrode in a specific embodiment of the present invention.

[0030] Figure 2 This is a schematic diagram of the structure of an ion capacitive pressure sensor in a specific embodiment of the present invention.

[0031] Figure 3 This is a schematic diagram of the negative pressure adsorption mold in a specific embodiment of the present invention.

[0032] Figure 4 This is a flowchart illustrating the fabrication process of the dome-shaped microstructure flexible electrode in one specific embodiment of the present invention.

[0033] Figure 5 This is a sensitivity comparison curve between microstructured electrodes and non-microstructured electrodes in a specific embodiment of the present invention.

[0034] Figure 6 This is a cyclic response curve of an ion-capacitive pressure sensor under different loads in a specific embodiment of the present invention.

[0035] Figure 7 This is a stability test diagram of an ion-capacitive pressure sensor under 2000 cycles at 200 kPa pressure, according to a specific embodiment of the present invention.

[0036] Figure 8 This is a schematic diagram illustrating the application of a four-channel pressure input module for game control in one specific embodiment of the present invention.

[0037] In the picture:

[0038] 1-Flexible encapsulation layer; 2-Flexible substrate layer; 3-Conductive microstructure layer; 4-Ion dielectric layer; 5-Counter electrode. Detailed Implementation

[0039] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0040] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "axial," "radial," "vertical," "horizontal," "inner," and "outer," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0041] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0042] Example 1

[0043] like Figure 2 As shown, the dome-shaped microstructure flexible electrode for an ion-capacitive pressure sensor of the present invention is composed of a three-layer composite structure: a flexible substrate layer 2, a conductive microstructure layer 3, and a flexible encapsulation layer 1. The flexible substrate layer 2 is sandwiched between the conductive microstructure layer 3 and the flexible encapsulation layer 1. The conductive microstructure layer 3 is the outermost layer of the flexible electrode; the flexible encapsulation layer 1 is attached to the back side of the flexible substrate layer 2. The conductive microstructure layer 3 has a dome-shaped array of protruding microstructures, distributed on the side of the conductive microstructure layer 3 facing the ion-dielectric layer 4, which increases the effective contact area between the conductive microstructure layer 3 and the ion-dielectric layer 4 during sensor assembly. The flexible substrate layer 2 provides the basic support for the entire conductive microstructure layer 3, while the flexible encapsulation layer 1 provides structural protection for the electrode from the back side.

[0044] In this embodiment, the flexible substrate layer 2 is prepared using PDMS material with an elastic modulus of 1.4~2 MPa, and the modulus can be controlled by adjusting the ratio of PDMS main agent to curing agent. The flexible encapsulation layer 1 uses PI (polyimide) tape, mainly serving as external encapsulation and protection. Under negative pressure adsorption, the conductive microstructure layer 3 undergoes local deformation synchronously with the flexible substrate layer 2 and adheres to the through-hole mold. After curing, the flexible substrate layer 2 forms an elastomer film of a certain thickness, whose elastic modulus and thickness, after configuration, can provide continuous support for the formed dome microstructure. At the same time, the pre-cured conductive microstructure layer 3 and the substrate layer 2 form a synergistic deformation structure during the negative pressure molding process. Both together suppress elastic recovery after demolding, ensuring the long-term stability of the microstructure size and morphology, thereby improving the structural stability and reusability of the flexible electrode.

[0045] It should be noted that PDMS is not the only material used to prepare the two layers mentioned above. In alternative embodiments, the flexible substrate 2 can also be made of Ecoflex silicone, which has an elongation of over 400% and a lower modulus, making it suitable for scenarios requiring large deformation or for scenarios requiring high wear resistance due to the higher mechanical strength of polyurethane. When different materials are used for the substrate and encapsulation layers, oxygen plasma treatment or an interfacial tackifier can be applied to the back of the substrate if necessary to improve the bonding strength between the encapsulation layer and the substrate layer and prevent interlayer separation during subsequent bending and use.

[0046] The conductive microstructure layer 3 is formed using stretchable conductive silver paste. The conductive silver paste consists of silver particles, thermosetting resin, and a diluent. After spin coating and curing, it forms a conductive film with a certain degree of flexibility, i.e., a conductive layer. After curing, the conductive silver paste possesses both good conductivity and a certain degree of stretchability. Especially when the flexible substrate layer 2 deforms, the conductive layer can deform along with the substrate without cracking or interrupting conductivity. In other embodiments, other stretchable conductive pastes containing graphene, carbon nanotubes, or metal nanoparticles can also be used, as long as the conductivity after curing is not less than 10. 4 The basic requirement is that the elongation at break (S / m) is not less than 20%.

[0047] Example 2

[0048] like Figure 4 As shown, the method for fabricating the dome-shaped microstructure flexible electrode described in Example 1 utilizes negative pressure suction to cause local deformation of the flexible composite film into the through-holes of the template, thereby forming a dome-shaped protrusion structure on the film surface corresponding to the through-hole array. Specifically, it includes the following steps:

[0049] S01: Preparation of flexible substrate layer 2. PDMS prepolymer and curing agent are mixed uniformly at a mass ratio of 10:1. After vacuum degassing, the mixture is coated onto a clean glass substrate surface using a spin coater. The spin coater speed is set to 2000 rpm, and the spin coater time is approximately 30 seconds. After coating, the glass substrate with the PDMS coating is placed on a heating platform for curing for 10 minutes. Upon curing, a PDMS flexible substrate layer 2 is obtained on the glass substrate surface. The thickness of the flexible substrate layer 2 is mainly determined by the spin coater speed and the viscosity of the PDMS mixture. The flexible substrate layer 2 serves to support the subsequent conductive silver paste layer and undergoes local deformation according to the morphology of the vias during negative pressure adsorption.

[0050] S02: Form a conductive layer on the surface of the flexible substrate layer 2. Before spin-coating the conductive silver paste, the surface of the PDMS flexible substrate layer 2 is first subjected to plasma treatment. The purpose of plasma treatment is to improve the hydrophilicity and surface energy of the PDMS surface, so that the subsequently spin-coated conductive silver paste can spread fully on the substrate surface without shrinkage or agglomeration. After plasma treatment, the conductive silver paste should be coated as soon as possible (generally within 5 minutes) to avoid the PDMS surface energy from decaying and recovering over time.

[0051] A stretchable conductive silver paste (commercially available product, solid content approximately 70%~80%) was uniformly drop-coated onto the plasma-treated substrate surface, followed by spin-coating at 2000 rpm for 30 seconds. After spin-coating, the PDMS film with the conductive silver paste layer was placed on an 80°C heating platform for pre-curing for 5 minutes, allowing the conductive silver paste layer to reach a surface-dry state. At this point, the surface of the silver paste layer no longer has fluidity, but the interior still retains a certain degree of deformability, so that it can deform with the substrate during the subsequent negative pressure adsorption process without cracking.

[0052] S03: Negative pressure adsorption molding. The PDMS / conductive silver paste composite film is peeled off the glass substrate as a whole. For example... Figure 3 As shown, a 3D-printed template made of photosensitive resin is used. Its surface has an array of circular through-holes penetrating the template thickness. This array of through-holes guides the flexible composite film to undergo localized deformation under negative pressure, thereby obtaining a dome-shaped microstructure array with relatively regular positions and morphologies. The diameter of the circular through-holes is 0.7 mm, and the center-to-center distance between adjacent through-holes is 1.05 mm. The peeled composite film is then bonded to the template with a conductive silver paste layer facing the template surface, ensuring the composite film completely covers all through-hole areas. During the bonding process, it is advisable to slowly roll and flatten the film from one side to the other, minimizing the possibility of air bubbles being trapped between the film and the template surface. Residual air bubbles can prevent the area from adhering tightly to the template under negative pressure, thus affecting the integrity of the dome-shaped protrusions.

[0053] The template with the composite film attached is placed on a negative pressure adsorption platform. The negative pressure system is activated to create a negative pressure environment in the sealed cavity below the template, with the negative pressure value set to 80 kPa. Under the suction effect of the negative pressure, the area of ​​the composite film corresponding to each through-hole location will undergo local deformation into the through-hole. Since the through-hole has a circular cross-section and the negative pressure is a uniformly distributed load perpendicular to the film surface, the deformed protrusions are dome-shaped. The flexible substrate layer 2, due to its low elastic modulus, can deform sufficiently, and the conductive microstructure layer 3, because it retains a certain degree of deformability in the pre-cured state, can deform synchronously with the substrate layer without peeling or cracking. The center distance between adjacent through-holes is greater than the diameter of the through-hole, leaving a gap of approximately 0.35 mm between adjacent protrusions, ensuring that each protrusion is independent during the molding process and does not merge or stick together. The negative pressure is maintained for 5 to 10 minutes to ensure that the deformation is fully achieved.

[0054] S04: Carefully peel the cured composite film from the template. Since the PDMS material itself is non-sticky and the template surface has not undergone any adhesive treatment, the composite film can be easily detached from the template surface. During peeling, apply force symmetrically and slowly to avoid excessive tearing that could cause localized excessive deformation of the film. After demolding, a complete dome-shaped microstructure flexible electrode is obtained. The conductive microstructure layer 3 in the flexible electrode is fixed to the dome-shaped protrusion formed by its negative pressure adsorption. The flexible substrate 2 provides structural support from the back, preventing significant morphological rebound of the microstructure after demolding. Furthermore, because the pre-cured silver paste layer and the substrate layer form a synergistic deformation structure, the residual stress after demolding is shared by both, thus maintaining the dome shape.

[0055] S05: A flexible encapsulation layer 1 is attached to the flexible substrate layer 2 to obtain the dome-shaped microstructure flexible electrode.

[0056] like Figure 1 As shown, cross-sectional observation of the obtained dome-shaped microstructure flexible electrode by scanning electron microscopy revealed that a continuous and tight interface bond was formed between the conductive silver paste layer and the PDMS flexible substrate. No obvious gaps or detachment areas were observed at the interface, further indicating that the conductive layer and the substrate layer underwent synchronous deformation during the negative pressure molding process, and the two remained in close contact throughout the deformation process without relative slippage.

[0057] Example 3

[0058] An ion-capacitive pressure sensor includes a dome-shaped microstructure flexible electrode, an ion dielectric layer 4, and a counter electrode 5 as described in Embodiment 1. The ion dielectric layer 4 is disposed between the dome-shaped microstructure flexible electrode and the counter electrode 5, and together with the dome-shaped microstructure flexible electrode, forms a capacitive sensing structure. The array of dome-shaped protruding microstructures of the dome-shaped microstructure flexible electrode faces the ion dielectric layer 4.

[0059] The ionic dielectric layer 4 is an ionogel film, which is formed by combining a polymer matrix and an ionic liquid. The polymer matrix is ​​polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP), and the ionic liquid is 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt ([EMIM][TFSI]). The mass ratio of PVDF-HFP to [EMIM][TFSI] is 1:3. PVDF-HFP is dissolved in N,N-dimethylformamide (DMF) solvent. After the PVDF-HFP is completely dissolved, the [EMIM][TFSI] ionic liquid is added and stirring continues to obtain a uniform ionogel precursor solution. This precursor solution is then coated onto a film using a blade coating method and heated to cure the film, causing the DMF solvent to evaporate, thus obtaining a flexible ionogel film. In a modified embodiment, spin coating can be used instead of blade coating to form the film.

[0060] An aluminum foil is cut to a preset size to serve as the counter electrode 5. The counter electrode 5, the ion-dielectric layer 4, and the dome-shaped microstructure flexible electrode are then stacked sequentially, with the ion-dielectric layer positioned between the counter electrode 5 and the dome-shaped microstructure flexible electrode. Subsequently, polyimide (PI) tape or other flexible encapsulation materials are used for edge encapsulation to obtain the ion-capacitive pressure sensor. This assembly method is simple and allows for easy adjustment of device size and electrode area according to application requirements.

[0061] The ion-capacitive pressure sensor prepared according to the above method was subjected to pressure response testing. Under external pressure loading conditions, the change of the sensor capacitance signal over time was recorded. The response time of the ion-capacitive pressure sensor was measured to be 90 ms, indicating that the dome-shaped microstructure flexible electrode can respond quickly to external pressure and convert changes in mechanical pressure into changes in capacitance signal.

[0062] like Figure 5 As shown, the sensitivity of an ion-capacitive pressure sensor using a dome-shaped microstructure electrode is compared with that of an ion-capacitive pressure sensor using a non-microstructure electrode. The test results show that the capacitance change of the sensor with the dome-shaped microstructure electrode is significantly higher than that of the sensor with the non-microstructure electrode; specifically, within the pressure range of 0–90 kPa, the sensitivity of the sensor with the dome-shaped microstructure electrode is 468.9 kPa. -1 Within a pressure range of 90–160 kPa, the sensitivity of the sensor corresponding to the dome-shaped microstructure electrode is 273.15 kPa. -1 The above results demonstrate that the array of dome-shaped protrusions can effectively increase the change in contact area between the electrode and the ion dielectric layer, thereby enhancing the interfacial electric double-layer capacitance effect.

[0063] like Figure 6As shown, under different pressure loads of 25 kPa, 50 kPa, 100 kPa, 150 kPa, and 200 kPa, the ion-capacitive pressure sensor exhibits repeatable capacitive response signals, and the response amplitude increases with increasing pressure, indicating that the sensor has good pressure resolution and repeatable load response capability. Figure 7 As shown, after 2000 cycles of stability testing at 200 kPa pressure, the sensor output signal remained relatively stable, indicating that the structure has good working stability under cyclic pressure.

[0064] like Figure 8 As shown, the ion-capacitive pressure sensor is constructed as a four-channel pressure input module for flexible human-computer interaction or game control scenarios. The four-channel pressure input module includes four independent pressure sensing units, a capacitance acquisition module, an Arduino controller, and a host computer. The four pressure sensing units correspond to channels ch0, ch1, ch2, and ch3, respectively, for acquiring pressure input signals from different positions. When a user presses a single pressure sensing unit or simultaneously presses two pressure sensing units, the capacitance signal of the corresponding channel changes. This change is acquired by the capacitance acquisition module and transmitted to the Arduino controller, where it is recognized by the host computer as corresponding game control commands. For example, a single-channel pressure input can correspond to actions such as jumping, moving down, moving left, or moving right; combined-channel pressure input can correspond to complex actions such as moving left and jumping, moving right and jumping, moving left and moving down, or moving right and moving down. Therefore, the ion-capacitive pressure sensor can serve as a flexible pressure input interface to achieve multi-channel game control and human-computer interaction.

[0065] Without departing from the inventive concept, the material of the flexible substrate layer 2 can be adjusted according to flexibility, stretchability, curing conditions, and application environment. For example, PDMS, Ecoflex silicone, polyurethane, or composites thereof can be used. The conductive microstructure layer can also be selected from different types of stretchable conductive pastes according to conductivity and stretchability requirements. For example, in applications requiring higher surface hardness and abrasion resistance (such as plantar pressure monitoring for wearable insoles), the flexible encapsulation layer 1 can be replaced with polyurethane to provide better mechanical protection.

[0066] The aperture, spacing, and array area of ​​the through-hole mold can be adjusted according to the range, sensitivity, and effective detection area of ​​the target sensor. In this specific method, a 0.7 mm aperture and a 1.05 mm center-to-center spacing are used to form a regular dome array. In other methods, the aperture, spacing, template thickness, or negative pressure can be conventionally adjusted while maintaining the basic morphology of the dome microstructure. Generally speaking: the larger the aperture, the larger the volume and height of a single protrusion, and the higher the rate of change of contact area in the low-pressure range, but the earlier deformation saturation may be reached in the high-pressure range; the smaller the aperture, the denser the protrusions, and the more contact points per unit area, but the deformation of a single protrusion is limited. The main function of the through-hole depth is to provide sufficient deformation space. If the depth is too shallow, the film deformation is limited, and the protrusion height is insufficient; if the depth is too large, the film may be excessively absorbed, leading to stress concentration at the bottom or even damage. Within a range of aperture diameters of 0.3 mm to 1.2 mm, center-to-center distances of 0.6 mm to 2.0 mm, and through-hole depths of 0.3 mm to 0.8 mm, a dome-shaped array with a certain degree of regularity can be obtained. Furthermore, the template itself is not limited to being prepared by 3D printing; it can also be processed using methods such as laser drilling, precision mechanical drilling, or photolithography etching.

[0067] In the embodiments, the preferred mass ratio of PVDF-HFP to [EMIM][TFSI] in the ionogel film is 1:3. This provides a high ion content for the ionogel, which is beneficial for forming a significant interfacial electric double-layer capacitance effect. Simultaneously, the PVDF-HFP polymer matrix maintains the flexibility and film integrity of the ionogel film. However, the mass ratio of PVDF-HFP to [EMIM][TFSI] in the ionogel is not limited to 1:3 and can be determined based on the balance between ionic conductivity and film stability. Generally, a higher ionic liquid content results in greater ionic conductivity and a more significant enhancement of interfacial capacitance, but a decrease in the mechanical strength of the film. Conversely, a lower ionic liquid content results in better mechanical strength and dimensional stability of the film, but a decrease in ionic conductivity. While maintaining sufficient mechanical strength to support subsequent assembly operations, the mass ratio can vary within the range of 1:2 to 1:4.

[0068] The ion-capacitive pressure sensor can be used as a single-channel pressure detection unit, or it can be further arrayed or multi-channeled for use in scenarios such as flexible human-computer interaction, direction control, health monitoring, or wearable input. By collecting pressure signals from different locations through multiple sensing units, multi-channel pressure input and interactive control can be achieved.

[0069] It should be understood that although this specification is described according to various embodiments, not every embodiment contains only one independent technical solution. This way of describing the specification is only for clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

[0070] The detailed descriptions listed above are merely specific illustrations of feasible embodiments of the present invention and are not intended to limit the scope of protection of the present invention. All equivalent embodiments or modifications made without departing from the spirit of the present invention should be included within the scope of protection of the present invention.

Claims

1. A dome-shaped microstructure flexible electrode for use in an ion-capacitive pressure sensor, characterized in that, It includes a flexible substrate layer (2), a conductive microstructure layer (3), and a flexible encapsulation layer (1); the flexible substrate layer (2) is sandwiched between the conductive microstructure layer (3) and the flexible encapsulation layer (1); the conductive microstructure layer (2) has a dome-shaped array of protruding microstructures to increase the effective contact area between the conductive microstructure layer (3) and the ion dielectric layer.

2. The dome-shaped microstructure flexible electrode for an ion-capacitive pressure sensor according to claim 1, characterized in that, The dome-shaped protrusion microstructure array is formed by causing the flexible substrate layer (2) and the conductive microstructure layer (3) to undergo local deformation through negative pressure adsorption.

3. The dome-shaped microstructure flexible electrode for an ion-capacitive pressure sensor according to claim 1, characterized in that, The flexible substrate layer (2) and the flexible encapsulation layer (1) are prepared using one or more of PDMS, Ecoflex silicone or polyurethane.

4. The dome-shaped microstructure flexible electrode for an ion-capacitive pressure sensor according to claim 1, characterized in that, The conductive microstructure layer (3) is formed using stretchable conductive silver paste.

5. An ion-capacitive pressure sensor, characterized in that, It includes the dome-shaped microstructure flexible electrode, the ion dielectric layer (4), and the counter electrode (5) as described in any one of claims 1-4; the ion dielectric layer (4) is disposed between the dome-shaped microstructure flexible electrode and the counter electrode (5), and together with the dome-shaped microstructure flexible electrode, forms a capacitive sensing structure; the array of dome-shaped protrusions of the dome-shaped microstructure flexible electrode faces the ion dielectric layer (4).

6. The ion-capacitive pressure sensor according to claim 5, characterized in that, The ionic dielectric layer (4) is an ionic gel film, which is formed by combining a polymer matrix and an ionic liquid.

7. The ion-capacitive pressure sensor according to claim 6, characterized in that, The polymer matrix is ​​PVDF-HFP, the ionic liquid is [EMIM][TFSI], and the mass ratio of PVDF-HFP to [EMIM][TFSI] is 1:2 to 1:

4.

8. The ion-capacitive pressure sensor according to claim 5, characterized in that, The counter electrode (5) is a flexible planar electrode; the flexible planar electrode is an aluminum foil or a flexible polymer film coated with a conductive layer.

9. The ion-capacitive pressure sensor according to claim 5, characterized in that, The dome-shaped microstructure flexible electrode, the ion dielectric layer (4), and the counter electrode (5) are stacked sequentially along the thickness direction. One surface of the ion dielectric layer (4) abuts against the top of the dome-shaped protruding microstructure array, and the other surface of the ion dielectric layer (4) is attached to the surface of the counter electrode (5).

10. A method for fabricating a dome-shaped microstructure flexible electrode according to any one of claims 1-5, characterized in that, Includes the following steps: Prepare a flexible substrate layer (2); A stretchable silver paste is spin-coated onto the surface of the flexible substrate (2) to form a conductive layer; A flexible substrate layer (2) with a conductive layer is attached to a template with an array of through holes, with the conductive layer facing the template. A negative pressure is applied to cause the flexible substrate layer (2) and the conductive layer to undergo local deformation into the through holes, forming a dome-shaped protrusion microstructure array. Release the negative pressure and remove the template, then attach the flexible encapsulation layer (1) to the flexible substrate layer (2) to obtain a dome-shaped microstructure flexible electrode.

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