Pressure detection system

Abstract

The invention discloses a pressure detection system, and relates to the technical field of intelligent wearing, and the pressure detection system comprises 1) a flexible substrate layer which is used for fitting skin and sensing external tiny pressure changes; the micro-column array layer is composed of a plurality of micro-column structures and used for amplifying and conducting the pressure change sensed by the flexible substrate layer; the flexible gel sensing layer is used for receiving the pressure transmitted by the micro-column array layer and generating an electric signal; 4) a packaging layer; an interdigital electrode layer is arranged in the flexible gel sensing layer, an electric signal of the flexible gel sensing layer changes along with the change of external pressure, and the detection of a pressure electric signal is realized through the interdigital electrode layer. By means of the design, high-sensitivity response to tiny pressure changes can be achieved, micro-pressure signals are remarkably amplified, meanwhile, the problem of hysteresis effect generally existing in traditional silica gel or metal film materials is solved, and therefore the response speed of the sensor is greatly increased.

Description

Technical Field

[0001] The present application relates to the field of intelligent wearable technology, and in particular to a pressure detection system, which can be widely used in the fields of intelligent wearable devices, clinical physiological parameter monitoring and remote health management. Background Art

[0002] With the widespread application of smart wearable medical devices in clinical continuous monitoring and individual health management, photoplethysmography (PPG) technology has become a core method for assessing cardiovascular physiological parameters. However, current mainstream wearable PPG sensors still face significant challenges in dynamic monitoring environments: the contact pressure between the sensor and the skin surface easily fluctuates with motion, leading to PPG signal baseline drift, distortion, and increased noise. Existing devices also lack the ability to amplify signals in the micro-pressure range, making it difficult to achieve both high-sensitivity detection and wide-area stress recognition, resulting in inaccurate data measurements. Summary of the Invention This application proposes a pressure detection system that is particularly suitable for PPG sensors to significantly improve their response speed, sensitivity and detection range.

[0003] The pressure detection of the present invention includes the following steps arranged in sequence: A flexible base layer that fits the skin and senses small external pressure changes; a micro-pillar array layer, composed of a plurality of micro-pillar structures, for amplifying and transmitting pressure changes sensed by the flexible base layer; a flexible gel sensing layer, configured to receive the pressure transmitted by the micropillar array layer and generate an electrical signal; and Encapsulation layer; The flexible gel sensing layer is provided with an interdigital electrode layer. The electrical signal of the flexible gel sensing layer changes with the change of the external pressure, and the pressure electrical signal is detected by the interdigital electrode layer.

[0004] It should be noted that the flexible gel sensing layer converts the pressure transmitted by the micropillar array layer into an electrical signal through force-to-electricity conversion. The electrical signal of the flexible gel sensing layer undergoes a repeatable and reversible response to changes in applied pressure, enabling highly sensitive detection of pressure signals through the interdigitated electrode layer.

[0005] This application realizes high-gain conversion of stress-electrical signals through the coupling structure of ionic hydrogel and microcolumns, achieves highly sensitive response to tiny pressure changes, amplifies tiny pressures, significantly amplifies tiny pressure signals, and overcomes the hysteresis effect problem commonly found in traditional silicone or metal film materials, thereby greatly improving the response speed of the sensor.

[0006] In some embodiments, the material composition of the flexible gel sensing layer includes an ionic hydrogel microsphere crosslinker, a crosslinked gel matrix, and conductive ions. The ionic hydrogel microsphere crosslinker is formed by polymerizing zwitterionic monomers and carboxyl polymer chains. The crosslinked gel matrix is ​​composed of gel monomers and polymer chains. The crosslinked gel matrix and the conductive ions form a stable metal coordination network structure through carboxyl coordination, which gives the material excellent force-electric response performance and structural stability. The zwitterionic monomer includes at least one of SBMA (sulfobetaine methacrylate) and DMAPS ([2-(methacryloyloxy)ethyl]dimethyl(3-sulfonic acid propyl)ammonium inner salt). The zwitterionic monomer has both anions and cations, which can form a stronger electrostatic coupling effect, provide ionic groups, and improve the ionic conductivity of the flexible gel sensing layer. It contains carboxyl groups to coordinate iron ions and can combine with primary amino groups to form amide bonds, thereby forming a stable sensing layer and improving the mechanical properties of the hydrogel network; and / or, The carboxyl polymer chain includes at least one of polyaspartic acid and its derivatives, polylysine and its derivatives, alginic acid and its derivatives, and hyaluronic acid and its derivatives. The carboxyl polymer chain contains ionic groups, which are conducive to electrical conductivity and can improve the ionic conductivity of the flexible gel sensing layer; and / or, The gel monomer includes at least one of acrylamide and its derivatives, acrylic acid and its derivatives, N,N-dimethylacrylamide and its derivatives; and / or The polymer chain includes at least one of polyvinyl alcohol (PVA), sodium carboxymethyl cellulose (CMC) and gelatin to enhance the flexibility and biocompatibility of the gel; and / or Conductive ions include Zn 2+ 、Fe 3+ , Ca 2+ and Mg 2+ At least one of these ions forms an adjustable three-dimensional metal coordination network structure with the carboxyl ligand through dynamic coordination, thereby constructing a sensing channel with high ionic conductivity and giving the gel excellent pressure response sensitivity, flexible adhesion performance and self-healing potential.

[0007] Specifically, the ionic hydrogel microsphere crosslinker is synthesized from zwitterionic monomers and carboxyl macromolecular chains through a reverse emulsion polymerization method. Subsequently, the carboxyl functional groups on the surface of the microspheres are activated using a glycidyl methacrylate (GMA) / tetra-n-butylammonium bromide (TBAB) solution system, and GMA is grafted to form a multifunctional microsphere structure, which significantly improves the crosslinking efficiency and compatibility between the microspheres and the hydrogel network.

[0008] In the optimized ratio design, the mass fractions of the zwitterionic monomer, carboxyl macromolecular chain, and GMA grafted chain are 15-20 wt%, 5-10 wt%, and 2.5-5 wt%, respectively, with the balance being solvent, to achieve a synergistic improvement in the chemical stability, interfacial activity, and ion channel regulation capabilities of the microsphere structure. This ionic hydrogel microsphere crosslinker not only provides abundant anionic and cationic sites as functional ion channels for the hydrogel matrix, but also forms a stable and flexible three-dimensional network structure through physical crosslinking (such as hydrogen bonding and electrostatic coupling) and covalent crosslinking, significantly enhancing the overall mechanical strength and fatigue resistance of the gel.

[0009] In some embodiments, the molar coordination ratio of the conductive ions to the carboxyl ligands in the cross-linked gel matrix is ​​1:(3-6), which helps to maintain the effectiveness and flexibility of the ion migration channel while ensuring the network strength, achieve efficient electron-ion cooperative conduction, improve the response speed and reduce the hysteresis error, thereby enhancing the flexibility and fatigue resistance of the material and the overall stability and dynamic performance of the pressure sensing system; and / or, The cross-linking density of the flexible gel sensing layer is distributed in a gradient-increasing manner from the micropillar array layer to the encapsulation layer. The cross-linking density of the flexible gel sensing layer gradually increases along the thickness direction from the micropillar array layer to the encapsulation layer. The cross-linking density refers to the number of cross-linking nodes per unit volume, reflecting the spatial density and mechanical stiffness level of the gel network. By constructing this gradient structure design, a soft, highly deformable low-cross-linking area is formed in the area close to the micropillar array layer to enhance the sensing sensitivity of the initial micro-pressure signal; while a high-cross-linking, high-elastic modulus support area is formed close to the encapsulation layer to withstand external loads and prevent premature crush failure. This gradient cross-linking design helps to construct a dual-channel enhancement area for mechanical and electrical signals, significantly improving the dynamic linear range, resolution and durability of the sensing system, and effectively suppressing the hysteresis effect and signal drift caused by multiple loadings.

[0010] In some embodiments, the flexible gel sensing layer includes a first layer and a second layer, with the first layer positioned between the flexible base layer and the second layer. The second layer's material is doped with carbon nanotubes (CNTs) to form a dense conductive network structure. This composite design significantly improves the volume conductivity of the second layer, enhancing both lateral electrical signal conduction and vertical strain response sensitivity during pressure loading.

[0011] In some embodiments, the thickness ratio of the first layer to the second layer is (1-3):1, which is configured to balance flexible conformability and force-to-electrical signal gradient conversion capability, thereby achieving excellent flexible distribution response and vertical conductive coupling effect, while ensuring the strain matching capability and efficient signal conduction performance of the sensor under complex biomechanical conditions; and / or, The carbon nanotubes in the second layer account for 0.3% to 0.8% by mass. This doping concentration allows for the construction of a uniform conductive pathway, optimizing pressure-impedance coupling performance and increasing signal amplification without significantly increasing the overall stiffness of the composite material. The introduction of carbon nanotubes not only imparts high conductivity to the material but also enhances the network's mechanical robustness and conductive stability through π-π stacking, further improving the system's overall dynamic response and reliability under multi-cycle loads. While maintaining flexibility and adhesion, a highly efficient force-to-electricity conversion conductive network is constructed.

[0012] In some embodiments, the micro-pillar array layer includes a plurality of micro-pillars, and the micro-pillar structure is a multi-level bionic spiral cavity structure, including a spiral guide shell layer wrapped on the outside and a slow-release cavity nested inside, wherein: The spiral guide shell has an asymmetric spinning spiral structure along the axial direction, which can achieve radial-axial coordinated deformation under the action of small pressure, significantly amplify the local stress conduction amplitude of the flexible substrate and enhance the primary trigger sensitivity; and / or, The sustained-release cavity is designed as a multi-stage collapse response structure, which can collapse layer by layer under external pressure, providing multiple deformation amplification effects and effectively protecting the integrity of the underlying structure. The multi-stage cavity structure achieves nonlinear stress amplification and multimodal stress response by regulating the collapse sequence of the microstructure, significantly improving the strain output and electrical signal amplitude modulation capabilities of the ion hydrogel layer; and / or, The cone angle of the micropillars is 30° to 60°, which is used to guide the orderly construction of ion migration channels, expand the dynamic detection range of the sensor, and realize the controllable stiffness gradient of the microstructure; The ratio of the height to the diameter of the microcolumns is 0.2 to 0.8, which is used to synergistically control the compression deformation range and the structural resilience, thereby maintaining structural stability while improving the deformability of the microcolumns and enhancing the strain amplitude transmission efficiency; and / or, The height of the microcolumns is 50~150 μm, which can accurately amplify tiny biomechanical disturbances to match the flexible mechanical properties and response frequency band of human skin.

[0013] It should be noted that in other embodiments, the cross-sectional shape of the microcolumn structure may also be conical, stepped columnar, wavy, or a multi-level spiral cavity structure, among which a bionic spiral-cavity combination structure is preferably used to achieve more excellent multi-dimensional mechanical response performance. This multi-scale bionic structure can achieve controllable and reversible radial-axial composite deformation under a small vertical load; under high pressure conditions, it exhibits a layer-by-layer collapse ductile response characteristic, thereby significantly amplifying the deformation of the flexible substrate and increasing the stress-induced electrical signal amplitude of the flexible gel sensing layer. Overall, this design significantly improves the system's force-to-electricity conversion efficiency and detection sensitivity, can effectively suppress the hysteresis effect and interface stress concentration phenomenon, and significantly enhances the stability of the microstructure and the overall mechanical durability of the device.

[0014] In some embodiments, the interdigitated electrode layer is composed of a plurality of distributed electrode units, and the arrangement density of these electrode units is arranged in a gradually increasing manner along the pressure conduction direction perpendicular to the flexible substrate (i.e., from the micro-pillar array layer to the packaging layer), thereby forming an asymmetric electric field sensing area. This asymmetric arrangement strategy can significantly improve the sensitivity of electrical signal extraction at different depth strain levels, enhance the system's ability to resolve small pressure gradient changes, and realize partitioned acquisition of multi-level pressure signals. Through the gradient distribution of the interdigitated electrode structure design, the spacing between adjacent electrodes is gradually distributed along the pressure loading direction, forming a resistance gradient amplification effect, thereby significantly enhancing the perception ability and signal amplification effect of small contact pressure changes, and improving the overall sensitivity and real-time response capability of the sensor. This design can effectively capture low-frequency small pressure disturbances, meet the needs of high-sensitivity detection, and significantly suppress background noise interference, optimizing the signal-to-noise ratio.

[0015] In some embodiments, the distribution density of the electrodes is in the range of 8 to 24 electrodes / cm²; and / or, The spacing Δd between adjacent electrode units ranges from 20 to 100 μm. By precisely controlling the electrode density and spacing parameters, a reasonable resistance gradient distribution can be formed along the pressure-applying path, creating an asymmetric electric field distribution to enhance the resolution and detection sensitivity of minute pressure signals. This structural design also helps effectively suppress electric field crosstalk, ensuring stable acquisition and reconstruction of multi-point distributed signals, and improving the sensor's reliability and adaptability in complex physiological environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0017] Figure 1 This is a structural diagram of a pressure detection system according to an embodiment of the present application.

[0018] Figure 2 This is an exploded diagram of a pressure detection system according to an embodiment of the present application.

[0019] Figure 3 Schematic diagram of the flexible gel sensing layer structure of a pressure detection system according to an embodiment of the present application.

[0020] Description of Figure Numbers: 100 pressure detection system; 1 flexible substrate layer; 2 micro-pillar array layer; 3 flexible gel sensing layer; 31 interdigitated electrode layer; 32 first layer; 33 second layer; 4 packaging layer. DETAILED DESCRIPTION

[0021] In order to enable those skilled in the art to better understand the present invention, the following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0022] With the widespread application of wearable medical devices in clinical monitoring, chronic disease management, and personalized health assessment, PPG technology has become an important means of non-invasively monitoring cardiovascular function. However, existing wearable PPG sensors still face significant technical bottlenecks in practical applications: the sensor-skin contact interface is susceptible to external interference (such as motion artifacts, environmental vibrations) and physiological activities (such as gait changes, breathing, and muscle contractions), resulting in frequent fluctuations in contact pressure, which in turn causes PPG signal baseline drift and increased noise interference. Existing pressure detection components are difficult to adapt to complex dynamic monitoring scenarios and generally suffer from significant response hysteresis, slow dynamic response speed, insufficient mechanical compliance, and limited sensitivity. As a result, contact pressure cannot be corrected in a timely manner, affecting the stability and accuracy of detection data.

[0023] To address these technical pain points, this application provides a pressure detection system. By constructing a flexible microstructure layer, an ion-conducting network, and a gradient-distributed electrode array, the system achieves highly sensitive detection of tiny external pressure disturbances. This effectively alleviates the signal drift and noise issues inherent in existing technologies, significantly improves response speed, and expands the detection range, thus providing an innovative solution for high-performance PPG sensors and wearable health monitoring devices.

[0024] First, as Figure 1 and Figure 2As shown, the present application provides a pressure detection system 100, comprising: Flexible base layer 1, used to fit the skin and sense small external pressure changes; a micro-pillar array layer 2, composed of a plurality of micro-pillar structures, for amplifying and transmitting pressure changes sensed by the flexible base layer; and The flexible gel sensing layer 3 is used to receive the pressure transmitted by the micro-pillar array layer and generate an electrical signal; Encapsulation layer 4, used to protect the structural stability of the pressure detection system 100; The flexible gel sensing layer is provided with an interdigital electrode layer. The electrical signal of the flexible gel sensing layer changes with the change of the external pressure, and the pressure electrical signal is detected by the interdigital electrode layer.

[0025] It should be noted that the flexible gel sensing layer converts the pressure transmitted by the micropillar array layer into an electrical signal through force-to-electricity conversion. The electrical signal of the flexible gel sensing layer undergoes a repeatable and reversible response to changes in applied pressure, enabling highly sensitive detection of pressure signals through the interdigitated electrode layer.

[0026] This application realizes high-gain conversion of stress-electrical signals through the coupling structure of ionic hydrogel and microcolumns, achieves highly sensitive response to tiny pressure changes, amplifies tiny pressures, significantly amplifies tiny pressure signals, and overcomes the hysteresis effect problem commonly found in traditional silicone or metal film materials, thereby greatly improving the response speed of the sensor.

[0027] In some embodiments, the material composition of the flexible gel sensing layer includes an ionic hydrogel microsphere crosslinker, a crosslinked gel matrix, and conductive ions. The ionic hydrogel microsphere crosslinker is formed by polymerizing zwitterionic monomers and carboxyl polymer chains. The crosslinked gel matrix is ​​composed of gel monomers and polymer chains. The crosslinked gel matrix and the conductive ions form a stable metal coordination network structure through carboxyl coordination, which gives the material excellent force-electric response performance and structural stability. The zwitterionic monomers include at least one of SBMA (sulfobetaine methacrylate) and DMAPS ([2-(methacryloyloxy)ethyl]dimethyl(3-sulfonic acid propyl)ammonium inner salt). The zwitterionic monomers have both anions and cations, which can form a stronger electrostatic coupling effect and provide ionic groups to improve the ionic conductivity of the flexible gel sensing layer. They contain carboxyl groups to bind iron ions and can bind to primary amino groups to form amide bonds, thereby forming a stable sensing layer and improving the mechanical properties of the hydrogel network.

[0028] The carboxyl polymer chain includes at least one of polyaspartic acid and its derivatives, polylysine and its derivatives, alginic acid and its derivatives, and hyaluronic acid and its derivatives. The carboxyl polymer chain contains ionic groups, which are conducive to conductivity and can improve the ionic conductivity of the flexible gel sensing layer.

[0029] The gel monomer includes at least one of acrylamide and its derivatives, acrylic acid and its derivatives, and N,N-dimethylacrylamide and its derivatives.

[0030] The polymer chain includes at least one of polyvinyl alcohol (PVA), sodium carboxymethyl cellulose (CMC) and gelatin to enhance the flexibility and biocompatibility of the gel.

[0031] Conductive ions include Zn 2+ 、Fe 3+ , Ca 2+ and Mg 2+ At least one of these ions forms an adjustable three-dimensional metal coordination network structure with the carboxyl ligand through dynamic coordination, thereby constructing a sensing channel with high ionic conductivity and giving the gel excellent pressure response sensitivity, flexible adhesion performance and self-healing potential.

[0032] Specifically, the ionic hydrogel microsphere crosslinker is synthesized from zwitterionic monomers and carboxyl macromolecular chains through a reverse emulsion polymerization method. Subsequently, the carboxyl functional groups on the surface of the microspheres are activated using a glycidyl methacrylate (GMA) / tetra-n-butylammonium bromide (TBAB) solution system, and GMA is grafted to form a multifunctional microsphere structure, which significantly improves the crosslinking efficiency and compatibility between the microspheres and the hydrogel network.

[0033] In the optimized ratio design, the mass fractions of the zwitterionic monomer, carboxyl macromolecular chain, and GMA grafted chain are 15-20 wt%, 5-10 wt%, and 2.5-5 wt%, respectively, with the balance being solvent, to achieve a synergistic improvement in the chemical stability, interfacial activity, and ion channel regulation capabilities of the microsphere structure. This ionic hydrogel microsphere crosslinker not only provides abundant anionic and cationic sites as functional ion channels for the hydrogel matrix, but also forms a stable and flexible three-dimensional network structure through physical crosslinking (such as hydrogen bonding and electrostatic coupling) and covalent crosslinking, significantly enhancing the overall mechanical strength and fatigue resistance of the gel.

[0034] In conjunction with the first aspect, in some embodiments provided herein, the molar coordination ratio between the conductive ions and the carboxyl ligands in the flexible gel sensing layer 3 is preferably 1:(3-6). The molar coordination ratio refers to the number of carboxyl functional groups that can be coordinated per unit metal ion. This ratio helps maintain the effectiveness and flexibility of the ion migration channel while ensuring network strength, achieving efficient electron-ion cooperative conduction, improving response speed and reducing hysteresis error, thereby enhancing the material's compliance, fatigue resistance, and the overall stability and dynamic performance of the pressure sensing system.

[0035] In combination with the first aspect, in some embodiments provided in the present application, the cross-linking density of the flexible gel sensing layer 3 is arranged to increase from the micropillar array layer 2 to the encapsulation layer 4. The cross-linking density of the flexible gel sensing layer 3 refers to the number of cross-linking points that form a stable network structure per unit volume, representing the spatial density and mechanical stiffness level of the gel network. It is arranged to increase from the micropillar array layer 2 to the encapsulation layer 4, and can form a soft, highly deformable, low-cross-linked region on the side close to the micropillar array layer to enhance the initial micro-pressure response sensitivity; while constructing a high-cross-linked, high-elastic modulus support region on the side close to the encapsulation layer to withstand large external loads and prevent the structure from yielding or collapsing prematurely. This gradient structure helps to construct a distributed enhancement region of the mechanical-electrical signal dual channel, significantly improving the overall dynamic linear range, resolution, and mechanical stability of the pressure sensing system, and effectively reducing the hysteresis effect and signal drift caused by multiple loading.

[0036] In combination with the first aspect, in some embodiments provided in this application, such as Figure 3 As shown, the flexible gel sensing layer 3 comprises a first layer 32 and a second layer 33. The first layer 32 is positioned between the flexible base layer 1 and the second layer 33. The first layer 32 serves to buffer the primary pressure load and enhance interfacial bonding strength. The second layer 33 is doped with carbon nanotubes (CNTs) to enhance the network structure, which is used to strengthen the lateral conductivity of electrical signals and the sensitivity of vertical strain response. This composite structural design significantly improves the volume conductivity of the second layer, enhances the transmission efficiency of the vertical pressure response signal, optimizes the signal accuracy and stability, and improves the structural stability and durability of the device under multiple loading cycles.

[0037] In combination with the first aspect, in some embodiments provided in the present application, the thickness ratio of the first layer 32 to the second layer 33 is (1~3):1; this ratio configuration takes into account both flexible fit and force-electric signal gradient conversion capability, thereby achieving excellent flexible distribution response and vertical conductive coupling effect, while ensuring the strain matching capability and efficient signal conduction performance of the sensor under complex biomechanical conditions.

[0038] In conjunction with the first aspect, in some embodiments provided herein, the carbon nanotubes comprise 0.3% to 0.8% by mass of the material in the second layer 33. This doping concentration enables the construction of a uniform conductive pathway, optimizing pressure-impedance coupling performance, and increasing signal amplification without significantly increasing the overall stiffness of the composite material. The introduction of carbon nanotubes not only imparts high electrical conductivity to the material but also enhances the network's mechanical robustness and conductive stability through π-π stacking, further improving the system's overall dynamic response performance and reliability under multi-cycle loads. While ensuring flexibility and adhesion, a highly efficient force-to-electricity conversion conductive network is constructed.

[0039] In combination with the first aspect, in some embodiments provided in the present application, the micropillar array layer 2 includes a plurality of micropillars, and the micropillar structure is a multi-level bionic spiral cavity structure, including a spiral guide shell layer coated on the outside and a slow-release cavity nested inside, wherein: the structure of the spiral guide shell layer is an axially asymmetric spin spiral form, which can produce a fast-response radial-axial coordinated deformation under the action of a small pressure, significantly amplifying the local deformation amplitude of the flexible substrate and improving the primary trigger sensitivity; the slow-release cavity is designed as a multi-level collapse response structure, which can collapse layer by layer under external pressure, providing multiple deformation amplification effects and effectively protecting the integrity of the underlying structure. This type of multi-level cavity structure achieves nonlinear stress amplification and multimodal stress response by regulating the collapse order of the microstructure, significantly improving the strain output and electrical signal amplitude modulation capabilities of the ion hydrogel layer.

[0040] In combination with the first aspect, in some embodiments provided in the present application, the micropillar array layer 2 includes a plurality of micropillars, wherein: the cone angle of the micropillars is 30°~60°, which helps to induce the ion migration channel to be constructed in a directional manner along a predetermined path, expand the dynamic detection range of the sensor, and help to adjust the micropillar stiffness gradient to achieve a balance between force conduction and response speed.

[0041] In combination with the first aspect, in some embodiments provided in the present application, the microcolumn array layer 2 includes a plurality of microcolumns, wherein: the ratio of the height to the diameter of the microcolumns is 0.2~0.8, which is used to synergistically control the compression deformation range and the structural rebound ability, so as to maintain structural stability while improving the deformability of the microcolumns and enhancing the strain amplitude transmission efficiency.

[0042] In combination with the first aspect, in some embodiments provided in the present application, the micropillar array layer 2 includes a plurality of micropillars, wherein: the height of the micropillars is 50~150 μm, which can achieve precise amplification of tiny pressure disturbances to match the mechanical response window of biological skin.

[0043] It should be noted that in other embodiments, the cross-sectional shape of the microcolumn structure may also be conical, stepped columnar, wavy, or a multi-level spiral cavity structure, among which a bionic spiral-cavity combination structure is preferably used to achieve more excellent multi-dimensional mechanical response performance. This multi-scale bionic structure can achieve controllable and reversible radial-axial composite deformation under a small vertical load; under high pressure conditions, it exhibits a layer-by-layer collapse ductile response characteristic, thereby significantly amplifying the deformation of the flexible substrate and increasing the stress-induced electrical signal amplitude of the flexible gel sensing layer. Overall, this design significantly improves the system's force-to-electricity conversion efficiency and detection sensitivity, can effectively suppress the hysteresis effect and interface stress concentration phenomenon, and significantly enhances the stability of the microstructure and the overall mechanical durability of the device.

[0044] In combination with the first aspect, in some embodiments provided in the present application, the interdigitated electrode layer 31 includes a plurality of electrode units, and the distribution density of the electrode units is arranged in a gradually increasing manner along the pressure conduction direction perpendicular to the flexible substrate (i.e., from the micro-pillar array layer to the packaging layer), thereby forming an asymmetric electric field sensing area. This asymmetric arrangement strategy can significantly improve the sensitivity of electrical signal extraction at different depth strain levels, enhance the system's ability to resolve small pressure gradient changes, and realize partitioned acquisition of multi-level pressure signals. Through the gradient distribution of the interdigitated electrode structure design, the spacing between adjacent electrodes is gradually distributed along the pressure loading direction, forming a resistance gradient amplification effect, thereby significantly enhancing the perception ability and signal amplification effect of small contact pressure changes, and improving the overall sensitivity and real-time response capability of the sensor. This design can effectively capture low-frequency small pressure disturbances, meet the needs of high-sensitivity detection, and significantly suppress background noise interference, thereby optimizing the signal-to-noise ratio.

[0045] Asymmetric interdigitated electrodes refer to the introduction of non-equidistant spacing distribution and different width configuration structures in adjacent electrode pairs to form a non-uniform electric field density area, which can achieve local sensitivity enhancement, directional distribution control of the response domain and noise shielding effect, further improving the sensor detection capability and stability.

[0046] In conjunction with the first aspect, in some embodiments provided herein, the electrodes are distributed at a density of 8 to 24 electrodes per square centimeter. The spacing Δd between adjacent electrode units is 20 to 100 μm. By controlling the electrode spacing Δd within this density range, a resistance gradient amplification effect along the pressure-applied path can be achieved while suppressing electric field crosstalk, ensuring stable acquisition and reconstruction of multi-point distributed signals.

[0047] The technical solution provided in this application is described in detail below with reference to embodiments.

[0048] Example 1 A pressure detection system The micropillar array was constructed on the surface of a flexible PDMS substrate using laser direct writing + mold replication technology. The cone angle was designed to be 45°, and the ratio of micropillar height to substrate diameter (h / D) was set to 0.5. The micropillar height was 100 μm, and 100 micropillars / cm 2 ; Using hydroxyethyl methacrylate and acrylic acid-zinc ion monomer (AA-Zn 2+ ) copolymerization to form a flexible gel sensing layer, with a molar coordination ratio of zinc ions to carboxyl ligands of 1:3. Ionic hydrogel microspheres prepared by reverse emulsion polymerization of SBMA / polyaspartic acid were used as crosslinkers, with the added amount accounting for 0.05wt% of the mass fraction of the entire reaction system. A gradient crosslinking structure was constructed by layered casting technology, with a gradient increasing distribution from the micropillar array layer to the encapsulation layer (with the initial crosslinking density set at 0.01mol / cm³ and the terminal crosslinking density set at 0.05mol / cm³). The total thickness was 0.5mm, of which the flexible gel sensing layer with a thickness of 0.25mm close to the encapsulation layer was added with 0.3% carbon nanotubes. Asymmetric interdigitated electrodes were deposited on the surface of the flexible gel sensing layer using magnetron sputtering and photolithography, and the electrode spacing was controlled to form a 50 μm gradient in the pressure loading direction. An encapsulation layer is prepared on the surface of the flexible gel sensing layer to obtain a pressure detection system.

[0049] Example 2 A pressure detection system A micropillar array was constructed on the surface of a flexible PDMS substrate using laser direct writing + mold replication technology. The cone angle was designed to be 55°, and the ratio of micropillar height to substrate diameter (h / D) was set to 0.8. The micropillar height was 150 μm, and 40 micropillars / cm 2 ; Hydroxyethyl methacrylate and acrylamide-ferric ion monomer (AM-Fe 3+ ) copolymerization to form a flexible gel sensing layer, with a molar coordination ratio of iron ions to carboxyl ligands of 1:6. Ionic hydrogel microspheres prepared by DMAPS / sodium alginate reverse emulsion polymerization were used as the crosslinker for the ionic hydrogel microspheres, with the added amount accounting for 0.08wt% of the mass fraction of the entire reaction system. A gradient crosslinking structure was constructed by layered casting technology, with a gradient increasing distribution from the micropillar array layer to the encapsulation layer (with the initial crosslinking density set at 0.02mol / cm³ and the terminal crosslinking density set at 0.08mol / cm³). The total thickness was 0.5mm, of which 0.3% carbon nanotubes were added to the 0.2mm thick flexible gel sensing layer close to the encapsulation layer. Asymmetric interdigitated electrodes were deposited on the surface of the flexible gel sensing layer using magnetron sputtering and photolithography, and the electrode spacing was controlled to form a 20 μm gradient in the pressure loading direction. An encapsulation layer is prepared on the surface of the flexible gel sensing layer to obtain a pressure detection system.

[0050] Example 3 A pressure detection system A micropillar array was constructed on the surface of a flexible PDMS substrate using laser direct writing + mold replication technology. The cone angle was designed to be 50°, and the ratio of micropillar height to substrate diameter (h / D) was set to 0.2. The micropillar height was 50 μm, and 60 micropillars / cm 2 ; Using N, N-dimethylacrylamide and acrylic acid-calcium ion monomer (AA-Ca 2+ ) copolymerization to form a flexible gel sensing layer, with a molar coordination ratio of calcium ions to carboxyl ligands of 1:4. Ionic hydrogel microspheres prepared by DMAPS / polylysine reverse emulsion polymerization were used as ionic hydrogel microsphere crosslinkers, with the added amount accounting for 0.05wt% of the mass fraction of the entire reaction system. A gradient crosslinking structure was constructed by layered casting technology, with a gradient increasing distribution from the micropillar array layer to the encapsulation layer (with the initial crosslinking density set at 0.015mol / cm³ and the terminal crosslinking density set at 0.06mol / cm³). The total thickness was 0.5mm, of which the flexible gel sensing layer with a thickness of 0.18mm near the encapsulation layer was added with 0.8% carbon nanotubes; Asymmetric interdigitated electrodes were deposited on the surface of the flexible gel sensing layer using magnetron sputtering and photolithography, and the spacing between the electrodes was controlled to form a 100 μm gradient in the pressure loading direction. An encapsulation layer is prepared on the surface of the flexible gel sensing layer to obtain a pressure detection system.

[0051] Comparative Example 1 The difference from Example 1 is that the micropillar array on the surface of the flexible PDMS substrate is replaced by an array without micropillars.

[0052] Comparative Example 2 The difference from Example 1 is that the flexible hydrogel sensing layer is replaced with a rigid double-network hydrogel (specifically, the material is poly (2-acrylamide-2-methylpropanesulfonic acid sodium salt): polyacrylamide in a mass ratio of 1:12).

[0053] Performance Testing In the static loading range of 0–50 kPa, the response time of the pressure detection systems of Examples 1 to 3 and Comparative Examples 1 to 2 was tested. The specific testing method is as follows: The response time is the time required for the output signal of the sensor to change from the initial value to the steady-state value during the external pressure loading or unloading process.

[0054] The test method is as follows: Use an Instron 5943 or equivalent precision device to vertically apply a certain pressure (e.g., 10 kPa) to the sensor at a set speed (e.g., 10 mm / min). Simultaneously connect a high-resolution data acquisition module (e.g., Keithley DAQ6510) to record the electrical signal changes in real time. Record the time it takes for the output voltage / resistance to reach the steady-state output value from the baseline value (the rising process); After removing the load, record the time it takes for the electrical signal to return to its initial state (recovery process); The average value is taken as the response time indicator.

[0055] The test results are shown in Table 1: Table 1 Performance of the pressure detection systems of Examples 1 to 3 and Comparative Examples 1 to 2

[0056] As can be seen from Table 1, the response time of the embodiment is significantly better than that of the comparative example. On the basis of the comparative example, the response time of Examples 1 to 3 of the present application is shortened.

[0057] Since Comparative Example 1 does not have a micropillar array, it lacks an effective mechanical signal amplification mechanism. The tiny pressure changes sensed by the flexible base layer cannot be fully transmitted to the gel sensing layer, resulting in a significant decrease in the response sensitivity of the overall system in the low-pressure range, an increase in the minimum detectable pressure threshold, and unstable strain transfer efficiency during pressure loading.

[0058] In Comparative Example 2, the flexible hydrogel sensing layer is replaced with a rigid double-network hydrogel layer. Since the electrical signal of the rigid double-network hydrogel layer does not change with the applied pressure, the sensitivity is low, the minimum detectable pressure threshold is increased, and the resolution is low.

[0059] In summary, the electrical signal from the flexible gel sensing layer changes with pressure, achieving a highly sensitive response to minute pressure changes. This amplifies the tiny pressures, alleviates the hysteresis effect present in traditional silicone or metal films, and significantly improves the overall response speed of the sensor. Furthermore, the flexible gel sensing layer provides a buffering effect, reducing signal drift and noise when pressure changes significantly, thereby improving the accuracy of signal transmission.

[0060] In the description of this application, it should be noted that the terms "upper" and "lower" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this application. Unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be internal communication between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to the specific circumstances.

[0061] It should be noted that, in this application, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprising a ..." does not exclude the presence of other identical elements in the process, method, article or device comprising the element.

[0062] The foregoing is merely a list of specific embodiments of the present application, intended to enable those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application is not limited to the embodiments shown herein, but is intended to conform to the broadest scope consistent with the principles and novel features of the present application.

Claims

1. A pressure detection system, characterized in that: Including the following settings: A flexible base layer that fits the skin and senses small external pressure changes; a micro-pillar array layer, composed of a plurality of micro-pillar structures, for amplifying and transmitting pressure changes sensed by the flexible base layer; a flexible gel sensing layer, configured to receive the pressure transmitted by the micropillar array layer and generate an electrical signal; as well as Encapsulation layer; The flexible gel sensing layer is provided with an interdigital electrode layer. The electrical signal of the flexible gel sensing layer changes with the change of the external pressure, and the pressure electrical signal is detected by the interdigital electrode layer.

2. The pressure detection system according to claim 1, wherein: The material composition of the flexible gel sensing layer includes an ionic hydrogel microsphere crosslinker, a crosslinked gel matrix, and conductive ions. The ionic hydrogel microsphere crosslinker is formed by polymerizing zwitterionic monomers and carboxyl polymer chains. The crosslinked gel matrix is ​​composed of gel monomers and polymer chains, wherein: The zwitterionic monomer includes at least one of SBMA and DMAPS; and / or, The carboxyl polymer chain includes at least one of polyaspartic acid and its derivatives, polylysine and its derivatives, alginic acid and its derivatives, hyaluronic acid and its derivatives; and / or, The gel monomer includes at least one of acrylamide and its derivatives, acrylic acid and its derivatives, N,N-dimethylacrylamide and its derivatives; and / or The polymer chain comprises at least one of polyvinyl alcohol, sodium carboxymethyl cellulose and gelatin; and / or Conductive ions include Zn 2+ 、Fe 3+ , Ca 2+ and Mg 2+ At least one of .

3. The pressure detection system according to claim 2, wherein: The molar coordination ratio of the conductive ions to the carboxyl ligands in the cross-linked gel matrix is ​​1:(3-6); and / or, The cross-linking density of the flexible gel sensing layer is distributed in a gradient increasing manner from the micropillar array layer to the encapsulation layer.

4. The pressure detection system according to claim 2, wherein: The flexible gel sensing layer includes a first layer and a second layer. The first layer is located between the flexible base layer and the second layer. The material of the second layer is doped with carbon nanotubes.

5. The pressure detection system according to claim 4, wherein: The thickness ratio of the first layer to the second layer is (1-3):1; and / or, The mass proportion of the carbon nanotubes in the second layer is 0.3% to 0.8%.

6. The pressure detection system according to claim 1, wherein: The micro-pillar array layer includes a plurality of micro-pillars. The micro-pillar structure is a multi-level bionic spiral cavity structure, including a spiral guide shell layer wrapped on the outside and a slow-release cavity nested inside, wherein: The spiral guide shell is in an asymmetric self-spinning spiral shape along the axial direction and has radial-axial composite deformation capability; and / or, The sustained-release cavity can gradually collapse and deform under external pressure to amplify the response signal; and / or, The cone angle of the microcolumn is 30° to 60°; and / or, The ratio of the height to the diameter of the microcolumns is 0.2 to 0.8; and / or, The height of the microcolumns is 50-150 μm.

7. The pressure detection system according to claim 1, wherein: The interdigitated electrode layer is composed of a plurality of distributed electrode units, and the spatial distribution density thereof is distributed in a gradient increasing manner along the direction from the microcolumn array layer to the packaging layer.

8. The pressure detection system according to claim 7, wherein: The distribution density of the electrodes is 8 to 24 electrodes / cm²; and / or, The distance Δd between adjacent electrode units is 20~100μm.

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