High-temperature-resistant multi-modal flexible sensor array based on rotating negative poisson's ratio structure interlayer and preparation method and application thereof

Abstract

This invention relates to a high-temperature resistant multimodal flexible sensing array based on a rotating negative Poisson's ratio structure interlayer, its fabrication method, and applications. The array comprises, from top to bottom, a top encapsulation layer, a temperature sensing layer, a negative Poisson's ratio structure interlayer, a piezoelectric sensing layer, and a substrate encapsulation layer. The negative Poisson's ratio structure interlayer is composed of a high-modulus flexible composite material and includes multiple rigid rotating units and flexible connecting regions, forming a rotating grid-like negative Poisson's ratio microstructure. The thermal resistance temperature sensing unit of the temperature sensing layer is located on the upper surface of the rigid rotating units and includes a graphene conductive network. The piezoelectric sensing layer includes a three-dimensional interconnected lead-free piezoelectric ceramic framework and arrayed stretchable electrodes, encapsulated in a flexible polymer matrix, for sensing mechanical deformation. Compared with existing technologies, the multimodal flexible sensing array of this invention possesses decoupling capabilities and can achieve independent output of temperature and mechanical deformation signals, making it a flexible multimodal sensor.

Description

Technical Field

[0001] This invention relates to a multimodal flexible sensing array, and more particularly to a high-temperature resistant multimodal flexible sensing array based on a rotating negative Poisson's ratio structure interlayer, its fabrication method, and its applications. Background Technology

[0002] With the rapid development of the Internet of Things (IoT), the demand for flexible sensors to operate stably in complex environments is constantly increasing. In recent years, researchers have developed various types of flexible sensors to detect multiple external stimuli, including mechanical, thermal, and chemical ones, and these sensors have been widely used in fields such as health monitoring, soft robotics, electronic skin, and structural diagnostics. However, most sensors are still limited to a single signal mode, mainly because there is mutual interference between different sensing mechanisms, making effective fusion difficult and severely restricting their multifunctional integration. In highly coupled systems such as lithium-ion batteries, temperature and mechanical strain often overlap, and processes such as heat accumulation, gas release, and electrode expansion are spatially uneven and mutually influential. Therefore, accurate diagnosis of their operating status urgently requires a high-performance sensing platform with the ability to decouple strain and temperature signals.

[0003] However, most existing multimodal sensing solutions are only suitable for low-temperature environments such as electronic skin, and still face problems such as functional degradation and signal interference in high-temperature fields. Developing highly sensitive and stable multimodal flexible sensors capable of operating in environments exceeding 100°C is crucial. To achieve reliable separation of multimodal signals, researchers have proposed various decoupling strategies relying on algorithmic identification in recent years, such as using external circuits and neural network models to analyze the coupled signals of sensors. However, these methods typically rely on high-performance computing modules, resulting in complex systems, high energy consumption, and difficulty in meeting the requirements of miniaturization and real-time response. In contrast, physical-level decoupling strategies based on the device structure itself, with their compactness and efficiency, have become an important development direction for multimodal fusion.

[0004] Common structural decoupling methods include: using the different sensitivities of materials to temperature and strain for identification, or physically separating different sensing units by arranging them in parallel or stacked within the device. The former is difficult to achieve a completely orthogonal response due to non-ideal coupling at the composite interface; while the latter avoids complex signal processing, mutual interference between sensing parameters may still affect the final decoupling accuracy.

[0005] CN114076564A proposes a strain sensor array based on a negative Poisson's ratio structure. While it possesses high sensitivity and large tensile strength, it is limited to strain detection and cannot simultaneously sense temperature and mechanical deformation. Furthermore, the stability of this sensor in high-temperature environments has not been fully verified, making it difficult to meet the demands of stringent applications such as lithium battery thermal runaway monitoring.

[0006] CN110426063A reports a dual-mode sensor that combines a piezoelectric layer and a piezoresistive layer to detect pressure and strain. However, this design lacks temperature sensing functionality, and the signals from the piezoelectric and piezoresistive layers are susceptible to mutual interference, making decoupling difficult. Its monitoring accuracy is limited when dealing with systems where temperature and mechanical deformation are highly coupled (such as lithium-ion batteries).

[0007] Therefore, there is an urgent need to develop a flexible multimodal sensor with decoupling capabilities that can independently output temperature and mechanical deformation signals. Summary of the Invention

[0008] The purpose of this invention is to overcome the defects of the prior art and provide a high-temperature resistant multimodal flexible sensing array based on a rotating negative Poisson's ratio structure interlayer, its fabrication method and application. The main development is a flexible multimodal sensor with decoupling capability that can independently output temperature and mechanical deformation signals.

[0009] The objective of this invention can be achieved through the following technical solutions:

[0010] The first aspect of this invention provides a high-temperature resistant multimodal flexible sensing array based on a rotating negative Poisson's ratio structure interposer, comprising, from top to bottom, a top encapsulation layer, a temperature sensing layer, a negative Poisson's ratio structure interposer, a piezoelectric sensing layer, and a substrate encapsulation layer, wherein:

[0011] The negative Poisson's ratio structure intermediate layer is made of a high-modulus flexible composite material, and the negative Poisson's ratio structure intermediate layer has a rotating grid negative Poisson's ratio microstructure containing multiple rigid rotating units and flexible connecting regions.

[0012] The temperature sensing layer includes a thermal resistance temperature sensing unit disposed on the upper surface of the rigid rotating unit by dispensing. The thermal resistance temperature sensing unit is used to sense changes in ambient temperature and includes a graphene conductive network.

[0013] The piezoelectric sensing layer includes a three-dimensional interconnected lead-free piezoelectric ceramic skeleton encapsulated in a flexible polymer matrix and an array of stretchable electrodes attached to the surface of the three-dimensional interconnected lead-free piezoelectric ceramic skeleton, thereby forming an array of piezoelectric sensing units. The piezoelectric sensing layer is used to sense mechanical deformation.

[0014] The substrate encapsulation layer is made of a thick flexible polymer, and the thickness of the substrate encapsulation layer is configured such that the temperature sensing layer and the piezoelectric sensing layer are far from the neutral axis of the sensing array.

[0015] The operating temperature range of the multimodal flexible sensing array is 25°C to 130°C.

[0016] Furthermore, the material of the three-dimensional interconnected lead-free piezoelectric ceramic framework is sodium potassium niobate, the microstructure is a three-dimensional porous network, and the crystal phase is a perovskite orthorhombic phase. The three-dimensional interconnected lead-free piezoelectric ceramic framework is prepared on a polymer foam template by template-assisted sol-gel method and then sintered.

[0017] Furthermore, the rigid rotating unit in the rotating grid negative Poisson's ratio microstructure has a size of 1.5mm × 1.5mm and a rotation angle of 30°–45°, and the width of the flexible connection area is 0.2–0.5mm;

[0018] The apex of the rigid rotating unit is completely covered by the flexible connecting area, forming a topologically continuous non-orthogonal hinge structure;

[0019] The center point of the rigid rotating unit coincides with that of the piezoelectric sensing unit.

[0020] Furthermore, the arrayed stretchable electrodes are coated onto the surface of the three-dimensional interconnected lead-free piezoelectric ceramic skeleton using a stencil printing process, and the electrode material is stretchable conductive silver paste.

[0021] Furthermore, the flexible polymer matrix of the top encapsulation layer, the base encapsulation layer, and the piezoelectric sensing layer are all polydimethylsiloxane.

[0022] A second aspect of the present invention provides a method for fabricating a high-temperature resistant multimodal flexible sensing array based on a rotating negative Poisson's ratio structure interlayer as described above, comprising the following steps:

[0023] S1: Fabrication of the piezoelectric sensing layer

[0024] The preparation of a three-dimensional interconnected lead-free piezoelectric ceramic framework using a template-assisted sol-gel method includes: dissolving alkali metal acetate and niobium ethanol in an organic solvent in a preset ratio, adding a sintering compensator and stirring and aging to form a precursor sol, uniformly coating the precursor sol onto the surface of a porous polymer template, and sintering to form a three-dimensional interconnected lead-free piezoelectric ceramic framework.

[0025] After cutting a three-dimensional interconnected lead-free piezoelectric ceramic skeleton, polarization treatment is performed, and a flexible polymer encapsulation is cast. Then, a stretchable electrode array is printed on the surface.

[0026] S2: Integration of temperature sensing layer and negative Poisson's ratio structure intermediary layer

[0027] Laser processing of rotating square negative Poisson's ratio microstructures on high modulus composite films enables flexible connection areas to completely cover the vertices of rigid units, forming non-orthogonal hinges.

[0028] A conductive paste with a negative temperature coefficient response is applied to the upper surface of a rigid unit and cured to form a thermal resistance temperature sensing unit.

[0029] S3: Full Component Assembly

[0030] Spin-coating adhesive onto a thick flexible polymer substrate;

[0031] The piezoelectric sensing layer, the negative Poisson's ratio intermediate layer, and the temperature sensing layer are stacked in sequence, and the positioning and matching make the temperature sensing unit correspond to the piezoelectric sensing unit in space.

[0032] A high-temperature resistant, multimodal flexible sensor array is obtained by curing a flexible polymer encapsulation layer.

[0033] Further, in S1, the specific steps for preparing the piezoelectric sensing layer include: dissolving potassium acetate and sodium acetate in ethylene glycol methyl ether at a molar ratio of 0.48:0.52, adding 3-10 mol% acetate to compensate for sintering loss, dissolving niobium ethanol in 2-methoxyethanol, and adding acetylacetone to regulate the hydrolysis rate. Then, the two solutions are combined and stirred for 6 hours, and aged at room temperature for 24 hours to obtain a precursor sol with a concentration of 0.5 M.

[0034] A polyurethane foam template with a thickness of 3 mm and a pore density of 40 ppi was fixed on the substrate of an ultrasonic spraying machine. The precursor sol was sprayed using ultrasonic spraying technology. The spraying parameters were: frequency 80 kHz, air pressure 0.5 MPa, nozzle speed 20-50 mm / s, liquid flow rate 6-15 μL / s, spray width 8 mm, and 15 sprays on each side.

[0035] The coated template is annealed at 1000°C for 40-90 min to form a three-dimensional interconnected lead-free piezoelectric ceramic skeleton.

[0036] The three-dimensional interconnected lead-free piezoelectric ceramic skeleton was cut into 6 cm × 6 cm dimensions and subjected to corona polarization treatment for 40 min.

[0037] Subsequently, PDMS encapsulation is poured to form a piezoelectric sensing layer. After the PDMS has cured, plasma treatment is performed on its surface, and stretchable silver paste is printed using a template to form an arrayed electrode pattern.

[0038] Furthermore, in S2, the specific steps for integrating the temperature sensing layer with the negative Poisson's ratio structure intermediary layer include:

[0039] PEDOT:PSS, sodium carboxymethyl cellulose, graphene and deionized water were mixed in a mass ratio of 9:3:1:60 to prepare a conductive suspension. The suspension was ultrasonically treated for 12-24 hours and stirred for another 24 hours to ensure uniform dispersion.

[0040] A 500 μm thick glass fiber-PDMS composite film was processed into a rotating square negative Poisson's ratio structure using a CO2 laser platform and then subjected to plasma treatment.

[0041] 3-8 μL of conductive suspension was applied to the rigid region of the rotating square negative Poisson's ratio structure using a dispensing method, and then cured at 80°C-140°C to form a temperature sensing unit.

[0042] The temperature sensing unit is connected to the external circuit by wire bonding to ensure stable signal transmission. Then, a PDMS layer is encapsulated on the temperature sensor to obtain a composite structure integrating the temperature sensing layer and the negative Poisson's ratio structure intermediary layer.

[0043] Furthermore, in S3, the process of assembling all components includes:

[0044] Spin-coating adhesive onto a thick flexible polymer substrate;

[0045] The piezoelectric sensing layer, the negative Poisson's ratio structure intermediate layer, and the temperature sensing layer are stacked in sequence. The thermal resistance temperature sensing unit of the temperature sensing layer and the piezoelectric sensing unit of the piezoelectric sensing layer are spatially matched through positioning and matching.

[0046] Cover the top encapsulation layer and apply uniform pressure to ensure that the functional layers are tightly bonded together;

[0047] The process involves curing to form a high-temperature resistant, multimodal flexible sensor array.

[0048] A third aspect of this invention provides an application of a high-temperature resistant multimodal flexible sensing array based on a rotating negative Poisson's ratio structure interlayer, as described above. The multimodal flexible sensing array is attached to the surface of a lithium-ion battery to simultaneously detect the battery's surface temperature and mechanical deformation, thereby identifying abnormal states such as overheating and bulging. The specific method includes:

[0049] A multimodal flexible sensor array is attached to the surface of the battery packaging.

[0050] The process of heat accumulation inside the battery is simulated by heating, while gas is injected into the battery to simulate the bulging phenomenon.

[0051] Monitor the resistance change of the temperature sensing unit and the voltage output of the piezoelectric sensing unit;

[0052] Based on the characteristic curves of temperature and voltage changes, determine whether the battery is in an abnormal state of overheating or swelling.

[0053] This invention conceives a novel multimodal sensing decoupling strategy. Utilizing a high-modulus rotating lattice-type negative Poisson's ratio structure, it achieves physical independence and functional decoupling of the temperature and mechanical deformation sensing mechanisms, making it suitable for real-time monitoring of complex thermo-mechanical coupling states in high-temperature environments exceeding 100°C. Specifically, a negative Poisson's ratio structure with rotating units is constructed in a glass fiber reinforced PDMS composite film (GFF-PDMS) using laser cutting technology. A lead-free KNN-PDMS piezoelectric sensing layer, prepared by a template-assisted sol-gel method, is integrated on its lower surface. Simultaneously, a thermal resistance temperature sensing unit based on a small polaritr jump mechanism is assembled in the rigid region of the upper surface of the structure using a dispensing method. This composite structure exhibits geometric characteristics of rigid unit rotation and flexible connection region expansion during stretching. This effectively shields the temperature sensor from interference from mechanical strain response and transforms the uniaxial stretching of the piezoelectric layer into enhanced in-plane multi-directional deformation, thereby significantly improving the response sensitivity of the piezoelectric element in d31 mode. By decoupling functional partitioning and physical components at the structural level, independent sensing of temperature and deformation signals is achieved within the same device. Experimental results show that the temperature sensing unit exhibits a stable negative temperature coefficient (NTC) response within the 25–130°C range, with a maximum resistance change rate of -65%, and is unaffected by tensile deformation. The piezoelectric sensor can sensitively detect minute surface protrusion changes down to 5 μm, unaffected by temperature. When the sensor array is mounted on the surface of a pouch lithium battery, it can effectively identify early failure modes such as overheating and bulging, verifying the good applicability and development potential of this invention in engineering applications such as structural health monitoring under high-temperature environments.

[0054] Compared with the prior art, the present invention has the following beneficial effects:

[0055] (1) A novel temperature-strain decoupling strategy is proposed. By introducing a high-modulus negative Poisson's ratio structure, piezoelectric and thermal resistance sensors can work independently on the same platform without interfering with each other. At the same time, the structure design also provides deformation gain effect, which effectively improves the piezoelectric response sensitivity.

[0056] (2) A flexible 3-3 composite piezoelectric material based on lead-free KNN was successfully prepared, and its intrinsic performance deficiency was compensated by structural design, realizing real-time detection of surface protrusions as small as 5 μm.

[0057] (3) The device has good high-temperature stability. The temperature sensor maintains a stable NTC response (maximum resistance change -65%) in the range of 25–130°C. It is suitable for multi-modal information acquisition in high-temperature environments, and has important application prospects, especially in engineering safety monitoring scenarios such as lithium batteries. Attached Figure Description

[0058] Figure 1This is a flowchart illustrating the fabrication process of the multimodal sensing array in this embodiment.

[0059] Figure 2 This is a morphological comparison of the KNN piezoelectric framework and the template in the embodiments.

[0060] Figure 3 This is a transmission electron microscope (TEM) image of the KNN piezoelectric framework in the embodiment.

[0061] Figure 4 The X-ray diffraction pattern and piezoelectric microscopy characterization of the KNN framework prepared in the examples are shown.

[0062] Figure 5 The voltage output of the piezoelectric sensor prepared in this embodiment under a 5-20 μm protrusion deformation.

[0063] Figure 6 The temperature change curve of the temperature sensor prepared in this embodiment is shown.

[0064] Figure 7 This describes the effect of temperature on the output of the piezoelectric sensor prepared in this embodiment.

[0065] Figure 8 This describes the effect of pressure and bending deformation on the temperature sensor fabricated in this embodiment.

[0066] Figure 9 This is a phase transition temperature test diagram of the KNN framework prepared in the examples.

[0067] Figure 10 The strain characteristics of the multimodal sensor studied using Comosol in this embodiment are shown.

[0068] Figure 11 It is a multimodal sensor array that monitors the output of battery overheating and expansion. Detailed Implementation

[0069] Overall, this invention provides the design and fabrication of a multimodal flexible sensing array with dual-parameter sensing capabilities for both temperature and mechanical deformation. The invention proposes a novel decoupled sensing strategy: integrating a high-modulus rotating square negative Poisson's ratio structure thin film with a low-modulus 3-3 composite lead-free piezoelectric composite thin film based on a continuous KNN framework. The temperature sensing unit (PG sensor) is attached to a rigid region within the negative Poisson's ratio structure. During bending, these rigid regions only rotate, effectively isolating the influence of tensile strain on its resistance value. Simultaneously, the negative Poisson's ratio geometry transforms uniaxial deformation in the piezoelectric layer into in-plane multi-directional deformation, significantly improving piezoelectric output performance in the d31 mode. The fabricated piezoelectric layer possesses 100% tensile strength and can independently detect surface protrusion deformations down to 5 μm at temperatures up to 130°C. The temperature sensor exhibits a stable negative temperature coefficient (NTC) response (based on a small polaron hopping conduction mechanism) over a temperature range of 25 to 130°C, with a maximum resistance change of up to -65%, while remaining insensitive to pressure and bending. When applied to the surface of a pouch cell, this sensor array successfully identified abnormal conditions such as overheating and bulging, demonstrating its great potential for structural health monitoring in harsh engineering environments.

[0070] In view of this, this invention aims to propose a novel strategy for decoupling temperature and mechanical deformation signals. A high-modulus negative Poisson's ratio structure is used as an intermediary, enabling piezoelectric strain sensors and thermal resistance temperature sensors to operate independently on the same platform, avoiding signal interference between different sensing mechanisms. This negative Poisson's ratio structure not only achieves physical decoupling but also enhances the in-plane deformation response of the piezoelectric layer through a geometric amplification effect, thereby strengthening its output signal intensity. This invention fabricates a 3-3 type composite piezoelectric sensor based on lead-free KNN, exhibiting excellent flexibility and up to 100% stretchability. The multimodal sensor can also operate above 100°C. When this multimodal sensing array is applied to the surface of a pouch battery, it can successfully identify typical safety failure events such as overheating and bulging, demonstrating excellent practicality and environmental adaptability. This invention provides a new paradigm for the design of multimodal sensors with dual-parameter physical decoupling, possessing broad engineering application potential.

[0071] In specific implementation, an anisotropic, highly sensitive, flexible piezoelectric sensor includes the following steps:

[0072] (1) Fabrication of KNN ceramic piezoelectric sensing layer:

[0073] The KNN framework structure was prepared using a template-assisted sol-gel method, specifically including:

[0074] Potassium acetate and sodium acetate were dissolved in ethylene glycol methyl ether at a molar ratio of 0.48:0.52. 3-10 mol% acetate was added to compensate for sintering losses. Niobium ethanol was dissolved in 2-methoxyethanol in a glove box, and acetylacetone was added to regulate the hydrolysis rate. The two solutions were combined and stirred for 6 hours, then aged at room temperature for 24 hours to obtain a 0.5 M precursor sol. A 3 mm thick polyurethane foam template with a pore density of 40 ppi was fixed on a substrate of an ultrasonic sprayer. The KNN sol was sprayed using ultrasonic spraying with the following parameters: frequency 80 kHz, air pressure 0.5 MPa, nozzle speed 20-50 mm / s, liquid flow rate 6-15 μL / s, spray width 8 mm, and 15 sprays on each side. The sprayed template was annealed at 1000°C to form a KNN ceramic skeleton.

[0075] (2) Piezoelectric layer polarization and electrode construction: The KNN ceramic skeleton was cut into 6cm × 6cm size and subjected to corona polarization treatment for 40 min; then PDMS was cast to form a piezoelectric sensing layer. After the PDMS was cured, plasma treatment was performed on its surface, and stretchable silver paste was printed using a template to form an arrayed electrode pattern.

[0076] (3) Preparation of the temperature sensing layer: PEDOT:PSS, sodium carboxymethyl cellulose (CMC), graphene and deionized water were mixed at a mass ratio of 9:3:1:60 to prepare a conductive suspension. The suspension was ultrasonically treated for 12-24 hours and stirred for another 24 hours to ensure uniform dispersion. A 500μm thick glass fiber (GFF)-PDMS composite film was processed into a negative Poisson's ratio structure using a CO2 laser platform and subjected to plasma treatment. 3-8μL of conductive suspension was dropped onto the stable rigid region of the structure using a dispensing method and cured at 80°C-140°C to form a temperature sensing unit. After electrical connection, a PDMS layer was encapsulated on the temperature sensor to protect it from external environmental interference.

[0077] (4) Integration and assembly of multi-mode devices: A 4mm thick PDMS substrate is used as the bottom layer, and a 3mm thick piezoelectric layer and a 500μm thick temperature sensing layer are bonded together. Spin-coated PDMS is used as the adhesive. The piezoelectric unit and the temperature unit are in a 2×2 array unit correspondence. The PDMS substrate layer is used to make the sensing unit distributed away from the neutral axis to enhance the mechanical response sensitivity and achieve signal decoupling.

[0078] In specific implementation, the preparation method of KNN sol described in step 1) and the large-area preparation method assisted by ultrasonic spraying machine include the following specific steps:

[0079] Potassium acetate and sodium acetate were dissolved in ethylene glycol methyl ether at a molar ratio of 0.48:0.52, and 3-10 mol% acetate was added to compensate for sintering loss.

[0080] 2) Dissolve niobium ethanol in ethylene glycol methyl ether in a glove box, and add acetylacetone to regulate the hydrolysis rate; 3) Combine the two solutions and stir for 6 hours, and age at room temperature for 24 hours to obtain a precursor sol with a concentration of 0.5M.

[0081] 3) Fix a 3mm thick polyurethane foam template with a pore density of 40 ppi onto the substrate of an ultrasonic spraying machine, and spray the KNN sol using ultrasonic spraying technology. The spraying parameters are: frequency 80kHz, air pressure 0.5MPa, nozzle speed 20-50mm / s, liquid flow rate 6-15μL / s, spray width 8mm, and spray 15 times on each side.

[0082] In specific implementation, the annealing temperature of the KNN skeleton in step 1) is 1000°C and the annealing time is 40-90 min.

[0083] In specific implementation, the electrode pattern described in step 1) is coated on the surface of the KNN skeleton by template printing, and the silver paste used is a stretchable conductive silver paste.

[0084] In specific implementation, the negative Poisson's ratio structure of the temperature sensing layer in step 2) is a rotating lattice structure.

[0085] In specific implementation, the preparation steps of the temperature sensing layer in step 2) include:

[0086] The conductive suspension contains PEDOT:PSS, sodium carboxymethyl cellulose (CMC), graphene, and deionized water in a mass ratio of 9:3:1:60, and is mixed evenly by ultrasonication and stirring.

[0087] The conductive suspension is coated onto the negative Poisson's ratio template by dispensing.

[0088] The drying temperature for the conductive suspension is 80°C-140°C.

[0089] In specific implementation, the piezoelectric sensing layer and the temperature sensing layer described in step 4) are fully covered by spin coating and bonding using PDMS. The spin coating speed is 700 rpm and the spin coating time is 30 seconds.

[0090] In specific implementation, the overall packaging material of the device in steps 1)-4) is Sylgard 184 type PDMS, with a mass ratio of substrate component to curing agent of 10:1.

[0091] In specific implementation, the high-temperature resistant multimodal flexible sensing array based on the rotating negative Poisson's ratio structure interlayer includes, from top to bottom, a top encapsulation layer, a temperature sensing layer, a negative Poisson's ratio structure interlayer, a piezoelectric sensing layer, and a substrate encapsulation layer, wherein:

[0092] The negative Poisson's ratio structure intermediate layer is composed of a high-modulus flexible composite material and has a rotating grid negative Poisson's ratio microstructure containing multiple rigid rotating units and flexible connecting regions. The temperature sensing layer includes a thermal resistance temperature sensing unit disposed on the upper surface of the rigid rotating unit by dispensing. The thermal resistance temperature sensing unit is used to sense changes in ambient temperature and includes a graphene conductive network. The piezoelectric sensing layer includes a three-dimensional interconnected lead-free piezoelectric ceramic skeleton encapsulated in a flexible polymer matrix and an array of stretchable electrodes attached to the surface of the three-dimensional interconnected lead-free piezoelectric ceramic skeleton, thereby forming an array of piezoelectric sensing units. The piezoelectric sensing layer is used to sense mechanical deformation. The substrate encapsulation layer is composed of a thick flexible polymer layer, and the thickness of the substrate encapsulation layer is configured such that the temperature sensing layer and the piezoelectric sensing layer are far from the neutral axis of the sensing array. The operating temperature range of the multimodal flexible sensing array is 25°C to 130°C. The stability of this temperature range is due to the selection of materials and structural design of each layer, especially the high-modulus flexible composite materials of the negative Poisson's ratio interlayer and the substrate encapsulation layer, which can maintain good mechanical and electrical properties at high temperatures.

[0093] In practical implementation, the negative Poisson's ratio structure interlayer is composed of a high-modulus flexible composite material, featuring a rotating lattice negative Poisson's ratio microstructure containing multiple rigid rotating units and flexible connecting regions. When subjected to tension, the rigid rotating units primarily rotate, while the flexible connecting regions bear the tensile strain. The temperature sensing layer incorporates thermal resistance temperature sensing units on the upper surface of the rigid rotating units of the negative Poisson's ratio structure interlayer via dispensing. These thermal resistance temperature sensing units include a graphene conductive network, utilizing its resistance-temperature-dependent characteristics to achieve temperature sensing. Since the rigid rotating units primarily rotate during mechanical deformation, the temperature sensing units are almost unaffected by mechanical strain, thus achieving effective decoupling between temperature and mechanical deformation signals. The piezoelectric sensing layer uses a three-dimensional interconnected lead-free piezoelectric ceramic framework encapsulated within a flexible polymer matrix, with attached arrayed stretchable electrodes. This design combines the high sensitivity of piezoelectric materials with the stretchability of the flexible matrix, enabling the piezoelectric sensing layer to effectively sense mechanical deformation. The substrate encapsulation layer uses a thick flexible polymer layer with optimized thickness, ensuring that the temperature sensing layer and piezoelectric sensing layer are located away from the neutral axis of the sensing array. This increases the mechanical response sensitivity of the sensing layer, while the physical distance isolation further reduces the mutual interference between temperature and piezoelectric signals.

[0094] In specific implementation, the material of the three-dimensional interconnected lead-free piezoelectric ceramic framework is sodium potassium niobate, the microstructure is a three-dimensional porous network, and the crystal phase is a perovskite orthorhombic phase. The three-dimensional interconnected lead-free piezoelectric ceramic framework is prepared on a polymer foam template by template-assisted sol-gel method and then sintered. The rigid rotating unit size in the rotating square negative Poisson's ratio microstructure is 1.5mm × 1.5mm, the rotation angle is 30°–45°, and the width of the flexible connection region is 0.2–0.5mm.

[0095] In specific implementation, the apex of the rigid rotating unit is completely covered by the flexible connecting area, forming a topologically continuous non-orthogonal hinge structure; the center point of the rigid rotating unit coincides with that of the piezoelectric sensing unit. This design allows the rigid unit to rotate around its contact point with the flexible connecting area when subjected to external forces, similar to the function of a hinge, but different from a traditional orthogonal hinge, offering greater flexibility in rotation direction and amplitude. This non-orthogonal hinge structure effectively alters stress distribution. During mechanical deformation, the flexible connecting area primarily bears tensile strain, while the rigid rotating unit primarily rotates, preventing the rigid unit from bearing excessive tensile stress and thus protecting the temperature sensing unit on the rigid unit from interference signals caused by mechanical strain. The coincidence of the center point of the rigid rotating unit with that of the piezoelectric sensing unit allows the piezoelectric sensing unit to directly sense local stress changes caused by the rotation of the rigid rotating unit during mechanical deformation, improving the sensitivity and accuracy of piezoelectric sensing. At the same time, this spatial correspondence also helps to achieve precise decoupling of temperature and mechanical deformation signals, because the temperature sensing unit is located at the apex of the rigid rotating unit, while the piezoelectric sensing unit corresponds to the center of the rigid rotating unit. The two are spatially connected yet independent of each other, which facilitates the separate acquisition and processing of different types of signals.

[0096] In specific implementation, the arrayed stretchable electrodes are coated onto the surface of the three-dimensional interconnected lead-free piezoelectric ceramic skeleton using a stencil printing process, and the electrode material is stretchable conductive silver paste. The stencil printing process is a high-precision and high-efficiency fabrication method that enables precise patterning of the electrode material, ensuring good contact and electrical connection between the electrode and the piezoelectric ceramic skeleton. The use of stretchable conductive silver paste as the electrode material allows it to stretch or compress accordingly with the deformation of the piezoelectric ceramic skeleton and the flexible polymer matrix during mechanical deformation, without breaking or detaching, thus ensuring a stable electrical connection between the electrode and the piezoelectric ceramic skeleton.

[0097] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. Any features not explicitly described in this technical solution, such as preparation methods, materials, structures, composition ratios, connection structures, circuit structures, control methods, algorithms, etc., are considered common technical features disclosed in the prior art.

[0098] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification.

[0099] Before further describing specific embodiments of the present invention, it should be understood that the scope of protection of the present invention is not limited to the specific embodiments described below; it should also be understood that the terminology used in the embodiments of the present invention is for describing specific embodiments and not for limiting the scope of protection of the present invention. Test methods in the following embodiments that do not specify specific conditions are generally performed under conventional conditions or as recommended by the respective manufacturers.

[0100] When numerical ranges are given in the embodiments, it should be understood that, unless otherwise stated in the present invention, both endpoints of each numerical range and any value between the two endpoints may be selected. Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art. In addition to the specific methods, apparatus, and materials used in the embodiments, based on the knowledge of the prior art possessed by one of ordinary skill in the art and the description of this invention, any prior art methods, apparatus, and materials similar to or equivalent to those described, apparatus, and materials in the embodiments of this invention may be used to implement the present invention.

[0101] Example 1

[0102] This embodiment describes a method for fabricating a multimodal sensing array, which includes the following steps:

[0103] (1) Fabrication of KNN ceramic piezoelectric sensing layer: The KNN framework structure was prepared using a template-assisted sol-gel method, specifically including:

[0104] Potassium acetate and sodium acetate were dissolved in ethylene glycol methyl ether at a molar ratio of 0.48:0.52. 3-10 mol% acetate was added to compensate for sintering losses. Niobium ethanol was dissolved in 2-methoxyethanol in a glove box, and acetylacetone was added to regulate the hydrolysis rate. The two solutions were combined and stirred for 6 hours, then aged at room temperature for 24 hours to obtain a 0.5 M precursor sol. A 3 mm thick polyurethane foam template with a pore density of 40 ppi was fixed on a substrate of an ultrasonic sprayer. The KNN sol was sprayed using ultrasonic spraying with the following parameters: frequency 80 kHz, air pressure 0.5 MPa, nozzle speed 20-50 mm / s, liquid flow rate 6-15 μL / s, spray width 8 mm, and 15 sprays on each side. The sprayed template was annealed at 1000°C to form a KNN ceramic skeleton.

[0105] (2) Piezoelectric layer polarization and electrode construction:

[0106] The KNN ceramic skeleton was cut into 6cm × 6cm dimensions and subjected to corona polarization treatment for 40 min. Then, PDMS was cast to form a piezoelectric sensing layer. After the PDMS was cured, plasma treatment was performed on its surface, and stretchable silver paste was printed using a template to form an arrayed electrode pattern.

[0107] (3) Fabrication of the temperature sensing layer:

[0108] PEDOT:PSS, sodium carboxymethyl cellulose (CMC), graphene, and deionized water were mixed in a mass ratio of 9:3:1:60 to prepare a conductive suspension. The suspension was ultrasonically treated for 12-24 hours and then stirred for another 24 hours to ensure uniform dispersion. A 500 μm thick glass fiber (GFF)–PDMS composite film was processed into a negative Poisson's ratio structure using a CO2 laser platform and subjected to plasma treatment. 3-8 μL of the conductive suspension was then drop-added to stable, rigid regions within the structure using a dispensing method. The film was then cured at 80°C-140°C to form a temperature sensing unit. After electrical connection, a PDMS layer was encapsulated on the temperature sensor to protect it from external environmental interference.

[0109] (4) Integration and assembly of multi-mode devices: A 4mm thick PDMS substrate is used as the bottom layer, and a 3mm thick piezoelectric layer and a 500μm thick temperature sensing layer are bonded together. Spin-coated PDMS is used as the adhesive. The piezoelectric unit and the temperature unit are in a 2×2 array unit correspondence. The PDMS substrate layer is used to make the sensing unit distributed away from the neutral axis to enhance the mechanical response sensitivity and achieve signal decoupling.

[0110] Figure 2ab illustrates the structural evolution of the KNN ceramic framework prepared from a PU foam template, characterized using optical microscopy. After sintering, the KNN ceramic successfully inherited the three-dimensional porous structure of the polymer foam template, retaining both the macroscopically interconnected framework and the microscale pore details. Notably, despite the high-temperature treatment, the resulting ceramic framework exhibited minimal volume shrinkage, and the overall porous network structure remained intact. This dimensional stability is primarily attributed to the interconnected porous structure of the PU foam itself, effectively mitigating the stress concentration problem commonly encountered during sintering.

[0111] Figure 3 ab is a scanning electron microscope image of the KNN ceramic framework. Thanks to the precisely controlled sintering process, the resulting KNN framework exhibits a dense ceramic morphology with an average grain size of approximately 1 μm.

[0112] Figure 4 ab represents the X-ray diffraction (XRD) pattern and piezoelectric microscopy results of the KNN ceramics. XRD analysis was performed within the range of 20°–60° (2θ), showing that the sample exhibits a pure perovskite phase structure with no secondary phase diffraction peaks detected. The intensity ratio of the (220) to (002) diffraction peaks at approximately 45° is I... 220 / I 002 The ratio ≈ 2:1 further confirms that the KNN ceramic is a single orthorhombic (O-phase) at room temperature. The piezoelectric behavior of the KNN framework was further characterized by piezoelectric force microscopy (PFM). Figure 4 As shown in b, its phase-voltage curve exhibits obvious polarization reversal behavior, with a phase change close to 180°, indicating that the material has switchable spontaneous polarization characteristics under the action of an applied electric field. The corresponding amplitude-voltage curve shows a typical "butterfly" response, indicating that the material has good electromechanical coupling ability and a significant polarization-dependent piezoelectric coefficient.

[0113] Figure 5 The output voltage of the piezoelectric device is measured by placing a 5-20 μm gap at the center of the device. It can be seen that as the gap increases from 5 μm to 20 μm, the piezoelectric output increases from 6.74 mV to 14.12 mV.

[0114] Verification Example 1

[0115] The piezoelectric-piezoresistive multimodal sensing unit was fixed around its perimeter. A small deformation was applied to the center of the sensor using the tip of a linear motor, and the sensor's output performance was observed under different deformation magnitudes.

[0116] Figure 6ab is the temperature change curve of the temperature sensor. The logarithm of the normalized resistance, ln(R / T²), exhibits a clear linear relationship with the reciprocal of the temperature (1 / T) over a wide temperature range from 25°C to 130°C, strongly indicating that its main conduction mechanism conforms to the Small Polaron Hopping (SPH) model. The temperature sensor exhibits highly consistent resistance-temperature response characteristics across three heating cycles, with the maximum rate of change of resistance reaching approximately -65% as the temperature increases from 25°C to 130°C (see...). Figure 4 (a) This is due to the excellent heat resistance of the composite film.

[0117] Figure 7 The temperature-dependent output voltage response of the KNN-based piezoelectric sensing layer is demonstrated under a fixed applied force of 5 N. As the temperature increases to 110°C, the output voltage increases only slightly from 3.03V to 3.14V, consistent with the phase transition behavior observed in the DSC analysis, indicating that the device's piezoelectric performance is stable within this temperature range.

[0118] Figure 9 The differential scanning calorimetry (DSC) curves of KNN ceramics show two distinct endothermic peaks at approximately 187°C and 397°C, corresponding to the phase transitions from orthorhombic to tetragonal (O–T) and from tetragonal to cubic (T–C). Theoretically, near the O–T phase transition, the piezoelectric properties are slightly improved due to enhanced domain wall mobility; however, after the T–C phase transition, the material transforms into a paraelectric state, and the piezoelectric properties decrease sharply. Therefore, to ensure the thermal stability and functional reliability of the device, KNN-based piezoelectric devices are suitable for operation below 130°C.

[0119] Figure 8 ab presented the resistance change rate of the temperature sensor under different mechanical disturbance conditions (bending radius 8.3–25.72 mm, applied pressure 0.2–16 N). The results show that the resistance change rate is less than 0.1% under all conditions, indicating that mechanical disturbance has minimal impact on temperature sensing accuracy. This high resistance stability is mainly attributed to the negative Poisson's ratio structural design, which concentrates strain in the stretchable region, avoiding stress on the rigid region. Furthermore, the PEDOT:PSS / CMC / graphene composite film, due to its small size (approximately 2 mm) and micrometer-level thickness, exhibits strong resistance to deformation in both the transverse and thickness directions, further enhancing its stability in the thermo-mechanical decoupling sensing process.

[0120] Figure 9The temperature-dependent output voltage response of the KNN-based piezoelectric sensing layer is demonstrated under a fixed applied force of 5 N. As the temperature increases to 110°C, the output voltage increases only slightly from 3.03V to 3.14V, consistent with the phase transition behavior observed in the DSC analysis, indicating that the device's piezoelectric performance is stable within this temperature range.

[0121] Figure 10 AB is a three-dimensional finite element simulation model of the actual sample geometry, used to analyze strain distribution during deformation. This model is constructed using COMSOL, and its geometry is consistent with the real device. Figure 10 This indicates that during bending, strain is mainly distributed in the stretchable porous structure, while the rigid block region has almost no strain distribution. Figure 10 b shows the displacement distribution of the piezoelectric layer in the Y direction when a bending displacement is applied along the –X edge towards the –Z direction. The results show a positive displacement on the +Y side and a negative displacement on the –Y side, exhibiting an overall lateral expansion characteristic in the Y-axis direction. This lateral expansion is induced by the embedded negative Poisson's ratio structure and effectively transferred to the piezoelectric layer, thereby generating tensile strain in its in-plane and effectively improving the electromechanical coupling efficiency in the piezoelectric film.

[0122] In COMSOL, the deformation behavior employs a simplified cantilever beam configuration: one end is fixed, and the other end is subjected to vertical displacement. Compared to the complex situation in natural bending, where the two ends and the middle exhibit arched movement and the direction of force constantly changes, this design is more conducive to the quantitative analysis of strain distribution.

[0123] Verification Example 2

[0124] Because inducing battery explosions in an experimental environment is highly dangerous, this verification example constructs a simulation platform to simulate the thermally induced deformation behavior of lithium-ion batteries during thermal runaway. The platform uses aluminum-plastic film pouch material (commonly used for battery encapsulation) to simulate the battery structure. A heating plate simulates the internal heating process of the battery, while air is injected into the pouch using a syringe to reproduce the volume expansion phenomenon during battery bulging. A multimodal sensor is attached to the surface of the pouch to achieve simultaneous monitoring of temperature and deformation. First, the pouch is heated to 90°C to simulate the heat accumulation process, then 3 mL of air is injected to simulate the structural expansion caused by overheating, and the output of the multimodal sensor is observed.

[0125] Figure 11 The AC diagram shows that the four temperature sensors exhibit different resistance change trends during the heating process, but eventually all stabilize at a certain fixed value (see...). Figure 11c). The maximum resistance decreases were -38.47%, -42.45%, -48.79%, and -53.93%, corresponding to temperatures of 61.18°C, 66.69°C, 78.77°C, and 89.71°C, respectively. This difference in response time and amplitude is mainly due to the spatial temperature difference caused by uneven thermal conduction within the flexible package. During temperature changes, the piezoelectric signal remained essentially constant. However, at the start of the flexible package volume expansion, all four units simultaneously experienced a voltage increase of approximately 0.19V, corresponding to approximately 0.6% strain (see...). Figure 11 (b) is highly consistent with the actual deformation during the bulging process.

[0126] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A high temperature resistant multi-modal flexible sensing array based on rotating negative poisson's ratio structure interposer, characterized in that, It includes, from top to bottom, a top encapsulation layer, a temperature sensing layer, a negative Poisson's ratio structure interposer layer, a piezoelectric sensing layer, and a substrate encapsulation layer, wherein: The negative Poisson's ratio structure intermediate layer is made of a high-modulus flexible composite material, and the negative Poisson's ratio structure intermediate layer has a rotating grid negative Poisson's ratio microstructure containing multiple rigid rotating units and flexible connecting regions. The temperature sensing layer includes a thermal resistance temperature sensing unit disposed on the upper surface of the rigid rotating unit by dispensing. The thermal resistance temperature sensing unit is used to sense changes in ambient temperature and includes a graphene conductive network. The piezoelectric sensing layer includes a three-dimensional interconnected lead-free piezoelectric ceramic skeleton encapsulated in a flexible polymer matrix and an array of stretchable electrodes attached to the surface of the three-dimensional interconnected lead-free piezoelectric ceramic skeleton, thereby forming an array of piezoelectric sensing units. The piezoelectric sensing layer is used to sense mechanical deformation. The substrate encapsulation layer is made of a thick flexible polymer, and the thickness of the substrate encapsulation layer is configured such that the temperature sensing layer and the piezoelectric sensing layer are far from the neutral axis of the sensing array. The operating temperature range of the multimodal flexible sensing array is 25°C to 130°C.

2. The high-temperature resistant multimodal flexible sensing array based on a rotating negative Poisson's ratio structure interlayer according to claim 1, characterized in that, The material of the three-dimensional interconnected lead-free piezoelectric ceramic framework is sodium potassium niobate, the microstructure is a three-dimensional porous network, and the crystal phase is a perovskite orthorhombic phase. The three-dimensional interconnected lead-free piezoelectric ceramic framework is prepared on a polymer foam template by template-assisted sol-gel method and then sintered.

3. The high-temperature resistant multimodal flexible sensing array based on a rotating negative Poisson's ratio structure interlayer according to claim 1, characterized in that, The rigid rotating unit in the rotating grid negative Poisson's ratio microstructure has a size of 1.5mm × 1.5mm and a rotation angle of 30°–45°, while the width of the flexible connection area is 0.2–0.5mm. The apex of the rigid rotating unit is completely covered by the flexible connecting area, forming a topologically continuous non-orthogonal hinge structure; The center point of the rigid rotating unit coincides with that of the piezoelectric sensing unit.

4. The high-temperature resistant multimodal flexible sensing array based on a rotating negative Poisson's ratio structure interlayer according to claim 1, characterized in that, The arrayed stretchable electrodes are coated onto the surface of the three-dimensional interconnected lead-free piezoelectric ceramic skeleton using a stencil printing process, and the electrode material is stretchable conductive silver paste.

5. The high-temperature resistant multimodal flexible sensing array based on a rotating negative Poisson's ratio structure interlayer according to claim 1, characterized in that, The flexible polymer matrix of the top encapsulation layer, the base encapsulation layer, and the piezoelectric sensing layer are all polydimethylsiloxane.

6. A method for fabricating a high-temperature resistant multimodal flexible sensing array based on a rotating negative Poisson's ratio structure interlayer as described in any one of claims 1 to 5, characterized in that, Includes the following steps: S1: Fabrication of the piezoelectric sensing layer The preparation of a three-dimensional interconnected lead-free piezoelectric ceramic framework using a template-assisted sol-gel method includes: dissolving alkali metal acetate and niobium ethanol in an organic solvent in a preset ratio, adding a sintering compensator and stirring and aging to form a precursor sol, uniformly coating the precursor sol onto the surface of a porous polymer template, and sintering to form a three-dimensional interconnected lead-free piezoelectric ceramic framework. After cutting a three-dimensional interconnected lead-free piezoelectric ceramic skeleton, polarization treatment is performed, and a flexible polymer encapsulation is cast. Then, a stretchable electrode array is printed on the surface. S2: Integration of temperature sensing layer and negative Poisson's ratio structure intermediary layer Laser processing of rotating square negative Poisson's ratio microstructures on high modulus composite films enables flexible connection areas to completely cover the vertices of rigid units, forming non-orthogonal hinges. A conductive paste with a negative temperature coefficient response is applied to the upper surface of a rigid unit and cured to form a thermal resistance temperature sensing unit. S3: Full Component Assembly Spin-coating adhesive onto a thick flexible polymer substrate; The piezoelectric sensing layer, the negative Poisson's ratio intermediate layer, and the temperature sensing layer are stacked in sequence, and the positioning and matching make the temperature sensing unit correspond to the piezoelectric sensing unit in space. A high-temperature resistant, multimodal flexible sensor array is obtained by curing a flexible polymer encapsulation layer.

7. A high-temperature resistant multimodal flexible sensing array based on a rotating negative Poisson's ratio structure interlayer according to claim 6, characterized in that, In S1, the specific steps for preparing the piezoelectric sensing layer include: dissolving potassium acetate and sodium acetate in ethylene glycol methyl ether at a molar ratio of 0.48:0.52, adding 3-10 mol% acetate to compensate for sintering loss, dissolving niobium ethanol in 2-methoxyethanol, and adding acetylacetone to regulate the hydrolysis rate. Then, the two solutions are combined and stirred for 6 hours, and aged at room temperature for 24 hours to obtain a precursor sol with a concentration of 0.5 M. A polyurethane foam template with a thickness of 3 mm and a pore density of 40 ppi was fixed on the substrate of an ultrasonic spraying machine. The precursor sol was sprayed using ultrasonic spraying technology. The spraying parameters were: frequency 80 kHz, air pressure 0.5 MPa, nozzle speed 20-50 mm / s, liquid flow rate 6-15 μL / s, spray width 8 mm, and 15 sprays on each side. The coated template is annealed at 1000℃ for 40-90 minutes to form a three-dimensional interconnected lead-free piezoelectric ceramic skeleton. The three-dimensional interconnected lead-free piezoelectric ceramic skeleton was cut into 6cm×6cm size and subjected to corona polarization treatment for 40min; Subsequently, PDMS encapsulation is poured to form a piezoelectric sensing layer. After the PDMS has cured, plasma treatment is performed on its surface, and stretchable silver paste is printed using a template to form an arrayed electrode pattern.

8. A high-temperature resistant multimodal flexible sensing array based on a rotating negative Poisson's ratio structure interlayer according to claim 6, characterized in that, In S2, the specific steps for integrating the temperature sensing layer with the negative Poisson's ratio structure intermediary layer include: PEDOT:PSS, sodium carboxymethyl cellulose, graphene and deionized water were mixed in a mass ratio of 9:3:1:60 to prepare a conductive suspension. The suspension was ultrasonically treated for 12-24 hours and stirred for another 24 hours to ensure uniform dispersion. A 500 μm thick glass fiber-PDMS composite film was processed into a rotating square negative Poisson's ratio structure using a CO2 laser platform and then subjected to plasma treatment. 3-8 μL of conductive suspension was applied to the rigid region of the rotating square negative Poisson's ratio structure using a dispensing method, and then cured at 80℃-140℃ to form a temperature sensing unit. The temperature sensing unit is connected to the external circuit by wire bonding to ensure stable signal transmission. Then, a PDMS layer is encapsulated on the temperature sensor to obtain a composite structure integrating the temperature sensing layer and the negative Poisson's ratio structure intermediary layer.

9. A high-temperature resistant multimodal flexible sensing array based on a rotating negative Poisson's ratio structure interlayer according to claim 6, characterized in that, In S3, the process of assembling all components includes: Spin-coating adhesive onto a thick flexible polymer substrate; The piezoelectric sensing layer, the negative Poisson's ratio structure intermediate layer, and the temperature sensing layer are stacked in sequence. The thermal resistance temperature sensing unit of the temperature sensing layer and the piezoelectric sensing unit of the piezoelectric sensing layer are spatially matched through positioning and matching. Cover the top encapsulation layer and apply uniform pressure to ensure that the functional layers are tightly bonded together; The process involves curing to form a high-temperature resistant, multimodal flexible sensor array.

10. An application of a high-temperature resistant multimodal flexible sensing array based on a rotating negative Poisson's ratio structure interlayer as described in any one of claims 1 to 5, characterized in that, The multimodal flexible sensor array is attached to the surface of a lithium-ion battery to simultaneously detect the battery's surface temperature and mechanical deformation, thereby identifying abnormal states such as overheating and bulging. Specific methods include: A multimodal flexible sensor array is attached to the surface of the battery packaging. The process of heat accumulation inside the battery is simulated by heating, while gas is injected into the battery to simulate the bulging phenomenon. Monitor the resistance change of the temperature sensing unit and the voltage output of the piezoelectric sensing unit; Based on the characteristic curves of temperature and voltage changes, determine whether the battery is in an abnormal state of overheating or swelling.

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