Stretchable and compressible SEBS-CNTs / carbon sponge, flexible piezoresistive sensor and preparation method and application of flexible piezoresistive sensor

Abstract

The invention discloses a stretchable and compressible SEBS-CNTs / carbon sponge, a flexible piezoresistive sensor and a preparation method and application of the flexible piezoresistive sensor, and the method comprises the following steps: immersing melamine sponge into an aqueous dispersion of carbon nanotubes (CNTs), and carrying out vacuum impregnation and drying to obtain CNTs / melamine sponge; the CNTs / melamine sponge is annealed in the inert gas atmosphere, carbonization of a melamine sponge framework is completed, and a CNTs / carbon sponge material is obtained; and putting the CNTs / carbon sponge material into a solution containing SEBS (Styrene-Ethylene-Butylene-Styrene), carrying out vacuum impregnation treatment, and drying, so as to obtain the SEBS-CNTs / carbon sponge. The SEBS-CNTs / carbon sponge disclosed by the invention has excellent tensile property and compression property through a synergistic effect of coating of SEBS and CNTs, and a flexible sensor assembled based on the SEBS-CNTs / carbon sponge has a wide application prospect in the fields of intelligent wearable equipment, human-computer interaction interfaces and the like.

Description

Technical Field

[0001] This invention relates to a carbon sponge, specifically to a stretchable and compressible SEBS-CNTs / carbon sponge, a flexible piezoresistive sensor, its preparation method, and its application. Background Technology

[0002] With the rapid development of flexible electronics, smart wearable devices, and human-computer interaction systems, flexible sensors are showing broad application prospects in fields such as human motion monitoring, health assessment, intelligent control, and flexible structure state perception. These applications typically require sensors to operate stably in complex and variable mechanical environments. They not only need high sensitivity and rapid response to external pressure or strain signals, but also need to maintain good structural integrity and electrical stability under various deformation modes such as tension and compression.

[0003] Currently, the performance of flexible sensors largely depends on the sensitive material system and its internal structural design. Traditional flexible sensing materials often employ a composite of an elastomer matrix and conductive fillers to achieve force-to-electricity conversion. However, the conductive network in such systems often relies on the random contact or tunneling effect of the filler, making it prone to irreversible damage during significant stretching or repeated deformation, leading to signal drift or performance degradation. Furthermore, while single elastomer materials possess excellent tensile properties, they often struggle to achieve effective conductive path reconstruction under compression conditions, limiting their application in multi-mode flexible sensing.

[0004] Porous carbon sponge, a lightweight conductive material with a three-dimensional interconnected framework structure, possesses high porosity, low density, and good electrical conductivity. Under pressure, it exhibits a significant resistance response through pore contraction and changes in framework contact, thus attracting widespread attention in the field of flexible pressure sensing. However, carbon sponge itself has limited mechanical toughness, making it prone to framework fracture or structural damage under tensile deformation conditions, which makes it difficult to meet the tensile adaptability requirements of wearable devices under large-amplitude movements.

[0005] It should be noted that the information disclosed in the background section above is only used to enhance the understanding of the background of this disclosure, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0006] The purpose of this invention is to provide a stretchable and compressible SEBS-CNTs / carbon sponge, a flexible piezoresistive sensor, its preparation method, and its application. This invention addresses the shortcomings of existing carbon sponge materials in terms of tensile properties and the limitations of single elastomer materials in terms of compressive response. The SEBS-CNTs / carbon sponge of this invention maintains the porous structure and continuous conductive network of carbon sponge, while further enhancing the overall conductivity by introducing carbon nanotubes. At the same time, the introduction of SEBS elastomers significantly enhances the material's elastic recovery ability and tensile toughness, providing an ideal material for the development of high-performance flexible sensors.

[0007] To achieve the above objectives, the present invention provides a method for preparing stretchable and compressible SEBS-CNTs / carbon sponges, the method comprising: Melamine sponge was immersed in an aqueous dispersion of carbon nanotubes under vacuum conditions to load carbon nanotubes onto the surface of the three-dimensional interconnected framework of the melamine sponge. After drying, CNTs / melamine sponge was obtained. The CNTs / melamine sponge was then subjected to high-temperature annealing in an inert gas atmosphere at 1000-1200°C to carbonize the melamine sponge framework and transform it into a continuous three-dimensional porous carbon framework, while retaining the carbon nanotubes loaded on its surface, resulting in a CNTs / carbon sponge material. This CNTs / carbon sponge material was then placed in a hydrogen-containing... A solution of styrene-butadiene block copolymer (SEBS) is vacuum impregnated and then dried and cured to form a continuous elastic coating layer on the surface of the CNTs / carbon sponge skeleton, which does not completely fill its three-dimensional interconnected channels, thereby obtaining a stretchable and compressible SEBS-CNTs / carbon sponge. The SEBS-CNTs / carbon sponge uses carbonized melamine sponge and carbon nanotubes to form a continuous three-dimensional conductive skeleton, and SEBS, as an elastic support phase, deforms in tandem with the conductive skeleton, thus possessing both tensile deformation adaptability and compressive piezoresistive response capability.

[0008] Preferably, the annealing temperature in the preparation of the CNTs / carbon sponge material is 1100℃.

[0009] Preferably, the SEBS solution uses SEBS with a weight-average molecular weight (Mw) of 85,000 to 90,000.

[0010] Preferably, the mass ratio of carbon nanotubes to SEBS is 1:(5~200).

[0011] More preferably, the mass ratio of the carbon nanotubes to SEBS is 1:(6~32).

[0012] Preferably, the concentration of the aqueous dispersion of carbon nanotubes is 1~10 mg / mL; or / and the concentration of the SEBS solution is 50~250 mg / mL.

[0013] More preferably, the concentration of the aqueous dispersion of the carbon nanotubes is 4 to 10 mg / mL; or / and the concentration of the SEBS solution is 100 to 200 mg / mL.

[0014] Preferably, the melamine sponge has dimensions of 15cm*6cm*6cm, and the carbon nanotubes have a mass of 1~10g.

[0015] Preferably, the drying temperature in the preparation of the CNTs / melamine sponge is 100~200℃.

[0016] Preferably, in the preparation of the CNTs / melamine sponge, the vacuum impregnation time is 30~90 min.

[0017] Preferably, in the preparation of the CNTs / carbon sponge material, the inert gas is selected from high-purity argon or high-purity nitrogen.

[0018] Preferably, in the preparation of the SEBS-CNTs / carbon sponge, the impregnation time is 20~40 min.

[0019] Preferably, the drying temperature in the preparation of the SEBS-CNTs / carbon sponge is 80~150℃.

[0020] A second objective of this invention is to provide stretchable and compressible SEBS-CNTs / carbon sponges obtained by the aforementioned preparation method.

[0021] A third objective of this invention is to provide the application of the aforementioned SEBS-CNTs / carbon sponge in flexible sensors.

[0022] The fourth objective of this invention is to provide a stretchable piezoresistive flexible strain sensor containing the aforementioned SEBS-CNTs / carbon sponge.

[0023] The fifth objective of this invention is to provide a compressible piezoresistive flexible stress sensor containing the aforementioned SEBS-CNTs / carbon sponge.

[0024] Preferably, the electrodes are made of copper foil and are disposed at both ends or on the top and bottom surfaces of the SEBS-CNTs / carbon sponge. The electrodes are coated with conductive silver paste and copper wires are placed on them, and they are encapsulated using PDMS solution.

[0025] More preferably, the concentration of the PDMS solution is 20 mg / mL, and the drying temperature after packaging is 80~150℃. Preferably, the drying temperature is 120℃.

[0026] The present invention relates to stretchable and compressible SEBS-CNTs / carbon sponge, a flexible piezoresistive sensor, its preparation method, and its application. These inventions overcome the shortcomings of existing carbon sponge materials in tensile properties and the limitations of single elastomer materials in compressive response, offering the following advantages: This invention involves impregnating melamine sponge with a CNT solution and achieving in-situ high-temperature carbonization. This process integrates the carbonized melamine sponge with CNTs in situ, forming a three-dimensional conductive framework and constructing a multi-scale conductive network. Subsequently, SEBS elastomer, possessing excellent tensile properties, is introduced to create a three-dimensional porous conductive network structure that combines high tensile toughness with compressive response sensitivity. This approach aims to achieve a synergistic unification of "stretchable, compressible, and conductive" properties at the structural level. Specifically, CNTs are distributed on the surface of the carbon sponge framework, forming highly efficient conductive paths. SEBS, as an elastic coating layer, not only improves the tensile elongation at break but also, through the support and synergistic deformation of the porous carbon sponge framework by the elastomer, significantly enhances the overall structural stability under tensile conditions while maintaining the compressive response advantages of the carbon sponge.

[0027] The preparation method of this invention is simple, and by adjusting the CNT loading and SEBS coating concentration, the electrical and mechanical properties of the material can be flexibly adjusted, laying the foundation for its practical application in wearable health monitoring, flexible robot tactile feedback and other fields. Attached Figure Description

[0028] Figure 1 The diagram shows the structure of the stretchable piezoresistive flexible strain sensor (a) and the compressible piezoresistive flexible stress sensor (b) prepared according to the present invention.

[0029] Figure 2 The images are SEM images of the CNTs / carbon sponge of the present invention; (a) overall microstructure; (b)~(d) SEM magnified views of specific areas.

[0030] Figure 3 This is a graph showing the relationship between the density and conductivity of CNTs / carbon sponge according to the present invention.

[0031] Figure 4 The conductivity results are for the SEBS-CNTs / carbon sponge of this invention.

[0032] Figure 5 The results show the elongation at break of the SEBS-CNTs / carbon sponge of the present invention.

[0033] Figure 6 The compressive stress sensitivity results are for the flexible stress sensor prepared in Application Example 2 of this invention.

[0034] Figure 7The tensile strain sensitivity results are for the flexible stress sensor prepared in Application Example 1 of this invention.

[0035] Figure 8 The following are the sensing performance test results of the SEBS-CNTs / carbon sponge flexible sensor assembled in Application Example 2 of this invention: (a) 10,000 compression cycles under 50% strain; (b) Response capability.

[0036] Figure 9 The SEBS-CNTs / carbon sponge flexible sensor assembled in Example 2 of this invention responds to vocalization and pulse signals; (a) to (c) are vocalization detection; (d) is pulse signal detection. Detailed Implementation

[0037] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0038] It should be noted that: Unless otherwise specified in the examples, conditions should be followed according to standard conditions or the manufacturer's recommendations. Instruments whose manufacturers are not specified are all commercially available products. Raw materials and reagents whose manufacturers are not specified are all commercially available goods or can be prepared using known methods.

[0039] In this invention, all features defined in the form of numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are used only for simplicity and convenience. Accordingly, the description of numerical ranges or percentage ranges should be considered as covering and specifically disclosing all possible sub-ranges and individual numerical values ​​(including integers and fractions) within those ranges.

[0040] The features mentioned in this invention can be combined arbitrarily, and all possible combinations should be considered within the scope of this specification, provided that there is no contradiction in the combination of these features. Each feature disclosed in the specification can be replaced by any alternative feature that provides the same, equivalent, or similar purpose. Therefore, unless otherwise specified, the disclosed features are merely general examples of equivalent or similar features.

[0041] In the description of this invention, it should be noted that the terms "comprising," "including," or any other variations thereof are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0042] This invention provides a stretchable and compressible SEBS-CNTs / carbon sponge, a flexible piezoresistive sensor, its fabrication method, and its applications. Unlike traditional sensitive layer designs that use randomly dispersed conductive fillers, this invention constructs a composite structure system with carbon sponge / CNTs as a continuous three-dimensional conductive framework and SEBS as a flexible elastic support. The carbonized melamine sponge and CNTs interface are synergistically combined to form a three-dimensional conductive framework and construct a multi-scale conductive network. Then, SEBS is used to completely encapsulate and synergistically support the carbon sponge framework, structurally solving the problem of easy breakage of conductive pathways during stretching. This achieves multi-mode mechanical adaptability, enabling the flexible sensor to operate stably under both stretching and compression deformation modes, overcoming the technical limitations of existing carbon sponge sensors that primarily rely on compression response. The controlled SEBS infiltration and curing process allows for the formation of a stable composite without damaging the porous structure of the carbon sponge, avoiding local overfilling or structural collapse. Simultaneously, utilizing the three-dimensional interconnected pore structure of the carbon sponge / CNTs, reversible reconstruction of the conductive path is achieved under external force, thereby improving the repeatability and cyclic stability of the sensing signal. By designing a structural conductive network, the reliance on high filler content is reduced, avoiding material hardening and decreased deformation capacity caused by excessive filler. This invention maintains the material's high flexibility and large deformation capacity while constructing a continuous, low-noise piezoresistive response mechanism, balancing sensitivity and signal stability.

[0043] The process of this invention is relatively simple, with adjustable parameters and good repeatability, making it suitable for the large-scale fabrication and engineering applications of flexible sensors. The resulting flexible sensor can withstand repeated loading and unloading conditions in complex service environments, maintaining stable electrical performance during multiple cycles of stretching and compression. This invention expands the application scenarios of SEBS / carbon sponge composite flexible sensors in wearable monitoring, human-computer interaction, and flexible structure health monitoring, enhancing its practical value and industrialization potential.

[0044] Although Chinese patent CN110041558 A discloses "a honeycomb microstructure elastic conductive polyurethane sponge and its preparation and application", which also uses hydrogenated styrene-butadiene block copolymer SEBS, it uses SEBS to promote the dispersion and adhesion of CNTs on the polyurethane sponge. Moreover, it uses polyurethane sponge as elastomer and CNTs as conductive network, but there is still a lack of effective bonding between the two, which makes it very easy to fail. Furthermore, the detachment of CNTs can easily cause secondary damage. At the same time, the structure and properties of polyurethane sponge are completely different from those of carbonized sponge. Polyurethane sponge is very prone to plastic deformation and lacks effective tensile strength and conductivity.

[0045] The following examples provide a detailed description of the stretchable and compressible SEBS-CNTs / carbon sponge, flexible piezoresistive sensor, its preparation method, and its applications provided by the present invention.

[0046] The following is a description of some of the materials used in the examples: Melamine sponge (15 cm * 6 cm * 6 cm) was purchased from BASF; poly(styrene-ethylene-butene-styrene), abbreviated as SEBS, with a weight-average molecular weight Mw ≈ 89,000, was purchased from Adamas Reagent Co., Ltd.; polydimethylsiloxane (PDMS), a two-component (A / B) Dow Corning 184, was purchased from Dow Chemical Company; aqueous dispersion of CNTs was purchased from Jiangsu Xianfeng Nanomaterials Technology Co., Ltd.; cyclohexane was purchased from Lianbohua (Tianjin) Pharmaceutical Chemicals Co., Ltd.; copper foil (15 mm wide * 0.05 mm thick), conductive silver paste, and 0.1 mm thick copper wire were all commercially available.

[0047] Example 1 A carbon sponge material, the preparation method of which includes: Melamine sponge (size: 15cm*6cm*6cm) was cleaned in ethanol and then dried. The cleaned melamine sponge was annealed at 1100℃ for 2 hours in an argon atmosphere to complete the carbonization of the melamine sponge skeleton, and finally carbon sponge material was obtained.

[0048] The density of the carbon sponge material prepared in this embodiment is 5 mg / cm³. 3 Its electrical conductivity is 2.5 S / m.

[0049] Example 2 A CNTs / carbon sponge material, the preparation method of which includes the following steps: (1) The melamine sponge (size: 15cm*6cm*6cm) was washed in ethanol and then dried; the aqueous dispersion of CNTs was prepared into a solution with a concentration of 1 mg / mL; (2) The cleaned melamine sponge was immersed in the above 1000 mL CNTs solution, placed in a vacuum oven for 1 hour, and then transferred to a drying oven and dried at 180°C for 24 hours to achieve effective coating of CNTs on the melamine sponge skeleton and obtain CNTs / melamine sponge. (3) Subsequently, the above CNTs / melamine sponge was annealed at 1100°C for 2 hours in an argon atmosphere to complete the carbonization of the melamine sponge skeleton and finally obtain the CNTs / carbon sponge material.

[0050] The density of the CNTs / carbon sponge material prepared in this embodiment is 5.2 mg / cm³. 3 Its electrical conductivity is 20 S / m.

[0051] Example 3 A CNTs / carbon sponge material is prepared using a method that is basically the same as in Example 2, except that: In step (3), the aqueous dispersion of CNTs is prepared into a solution with a concentration of 2 mg / mL.

[0052] The density of the CNTs / carbon sponge material prepared in this embodiment is 5.8 mg / cm³. 3 Its electrical conductivity is 50 S / m.

[0053] Example 4 A CNTs / carbon sponge material is prepared using a method that is basically the same as in Example 2, except that: In step (3), the aqueous dispersion of CNTs is prepared into a solution with a concentration of 4 mg / mL.

[0054] The CNTs / carbon sponge material prepared in this embodiment has a density of 6.7 mg / cm³. 3 Its electrical conductivity is 120 S / m.

[0055] Example 5 A CNTs / carbon sponge material is prepared using a method that is basically the same as in Example 2, except that: In step (3), the aqueous dispersion of CNTs is prepared into a solution with a concentration of 6 mg / mL.

[0056] The CNTs / carbon sponge material prepared in this embodiment has a density of 7.5 mg / cm³. 3 Its electrical conductivity is 180 S / m.

[0057] Example 6 A CNTs / carbon sponge material is prepared using a method that is basically the same as in Example 2, except that: In step (3), the aqueous dispersion of CNTs is prepared into a solution with a concentration of 8 mg / mL.

[0058] The CNTs / carbon sponge material prepared in this embodiment has a density of 8.5 mg / cm³. 3 Its electrical conductivity is 300 S / m.

[0059] Example 7 A CNTs / carbon sponge material is prepared using a method that is basically the same as in Example 2, except that: In step (3), the aqueous dispersion of CNTs is prepared into a solution with a concentration of 10 mg / mL.

[0060] The CNTs / carbon sponge material prepared in this embodiment has a density of 9.3 mg / cm³. 3 Its electrical conductivity is 385 S / m.

[0061] Example 8 A SEBS-CNTs / carbon sponge material is prepared using a method basically the same as in Example 4, with the difference being: The prepared CNTs / carbon sponge material was vacuum impregnated in a 500 mL solution of SEBS in cyclohexane with a concentration of 50 mg / mL for 30 minutes, and then dried and cured in an oven at 120 °C.

[0062] The SEBS-CNTs / carbon sponge obtained in this embodiment has an electrical conductivity of 5 S / m, an elongation at break of 55%, and a compressible strain of 90%.

[0063] Example 9 A SEBS-CNTs / carbon sponge material is prepared using a method basically the same as in Example 8, with the difference being: The concentration of the SEBS cyclohexane solution used was 100 mg / mL.

[0064] The SEBS-CNTs / carbon sponge obtained in this embodiment has an electrical conductivity of 2 S / m, an elongation at break of 80%, and a compressible strain of 90%.

[0065] Example 10 A SEBS-CNTs / carbon sponge material is prepared using a method basically the same as in Example 8, with the difference being: The concentration of the SEBS cyclohexane solution used was 150 mg / mL.

[0066] The SEBS-CNTs / carbon sponge obtained in this embodiment has an electrical conductivity of 0.9 S / m, an elongation at break of 100%, and a compressible strain of 90%.

[0067] Example 11 A SEBS-CNTs / carbon sponge material is prepared using a method basically the same as in Example 8, with the difference being: The concentration of the SEBS cyclohexane solution used was 200 mg / mL.

[0068] The SEBS-CNTs / carbon sponge obtained in this embodiment has an electrical conductivity of 0.5 S / m, an elongation at break of 125%, and a compressible strain of 90%.

[0069] Example 12 A SEBS-CNTs / carbon sponge material is prepared using a method basically the same as in Example 8, with the difference being: The concentration of the SEBS cyclohexane solution used was 250 mg / mL.

[0070] The SEBS-CNTs / carbon sponge obtained in this embodiment has an electrical conductivity of 0.1 S / m, an elongation at break of 155%, and a compressible strain of 90%.

[0071] Application Example 1 A stretchable piezoresistive flexible strain sensor based on SEBS-CNTs / carbon sponge, the fabrication method of which includes: The SEBS-CNTs / carbon sponge porous material elastomer prepared in Example 11 was processed into a certain size, the specific size depending on the size required for testing, generally 5cm*1cm*0.5cm in length, width and height. The copper foil electrode size, depending on the size of the SEBS-CNTs / carbon sponge, was generally 1cm*1cm in length and width, and the thickness depended on the copper foil thickness of 0.05mm. Conductive silver paste was coated on the processed copper foil and copper wires were placed on it. Then it was adhered to the left and right ends of the processed SEBS-CNTs / carbon sponge and dried in an oven at 60°C for about 1 hour. It was then immersed in 200 mL of 20 mg / mL PDMS solution (A / B component mass ratio of 10:1) for overall encapsulation, and then placed in an oven at 120°C for drying, finally obtaining a stretchable piezoresistive flexible strain sensor (such as...). Figure 1 (a).

[0072] Application Example 2 A compressible piezoresistive flexible stress sensor based on SEBS-CNTs / carbon sponge, the preparation method of which includes: The SEBS-CNTs / carbon sponge porous material elastomer prepared in Example 11 was processed into a certain size, the specific size depending on the size required for testing, generally 1cm*1cm*0.5cm in length, width and height. The copper foil electrode size, depending on the size of the SEBS-CNTs / carbon sponge, was generally 1cm*1cm in length and width, and the thickness depended on the copper foil thickness of 0.05mm. Conductive silver paste was coated on the top and bottom sides of the processed copper foil, and copper wires were placed on it. Then it was adhered to the top and bottom sides of the processed SEBS-CNTs / carbon sponge and dried in an oven at 60°C for about 1 hour. It was then immersed in 200 mL of 20 mg / mL PDMS solution (A / B component mass ratio of 10:1) for overall encapsulation, and then placed in an oven at 120°C for drying, finally obtaining a compressible piezoresistive flexible stress sensor (such as...). Figure 1 (b).

[0073] Experimental Example 1: Structural Characterization The CNTs / carbon sponge microstructures prepared using Example 4 were imaged and observed using a scanning electron microscope (SEM).

[0074] The results are as follows Figure 2 As shown, Figure 2 'a' shows its overall microscopic morphology. Figure 2 b shows a further amplified CNT network. Figure 2 c and d show nanoscale CNTs, and the distribution and presence of CNTs in the carbon sponge were confirmed by SEM.

[0075] Experiment Example 2: Conductivity Test The conductivity of the carbon sponge porous materials prepared in Examples 1-7 was tested, and the specific experimental procedure is as follows: The samples were cut into uniform sizes, with a length, width, and height of 1cm*1cm*0.5cm, and tested using a four-probe resistivity meter.

[0076] like Figure 3 As shown, its density and conductivity are positively correlated. As the CNT content increases, the density gradually increases and the conductivity gradually increases.

[0077] The SEBS-CNTs / carbon sponge porous material elastomers prepared in Examples 8-12 were tested, and the specific experimental procedures are as follows: The samples were cut into uniform sizes, with a length, width, and height of 1cm*1cm*0.5cm, and tested using a four-probe resistivity meter.

[0078] like Figure 4 As shown, the electrical conductivity of SEBS-CNTs / carbon sponge porous elastomer gradually decreases with increasing SEBS content.

[0079] Experiment Example 3 Mechanical Property Testing The mechanical properties of the SEBS-CNTs / carbon sponge porous elastomers prepared in Examples 8-12 were tested, and the specific experimental procedures are as follows: The prepared SEBS-CNTs / carbon sponge porous material elastomer is processed into a certain size, the specific size depends on the size required for testing, generally the length, width and height are 5cm*1cm*0.5cm respectively, and then a tensile test is performed using a universal testing machine at a tensile speed of 2mm / min.

[0080] like Figure 5 As shown, with the gradual increase of SEBS content, the elongation at break is greater, indicating a greater tensile length. Figure 4 and 5 This indicates that SEBS has a significant impact on conductivity, and the assembly of flexible sensors should balance conductivity and tensile elongation at break.

[0081] Experiment Example 4: Sensor Performance Testing The flexible stress sensors prepared in corresponding use case 2 and application example 1 were tested for their compressive stress sensitivity and tensile strain sensitivity, respectively. The test procedures are as follows: The flexible sensors prepared in Application Examples 1 and 2 were connected to the electrodes of a digital source meter (Keithley 2450), then fixed under the clamps of a universal testing machine and the test was started.

[0082] like Figure 7 As shown, the tensile strain sensitivity results of the flexible stress sensor prepared in Example 1 are shown. The maximum linear phase reaches approximately GF=17.5.

[0083] like Figure 6 The figure shows the compressive stress sensitivity results of the flexible stress sensor prepared in Example 2. The sensitivity ranges from 0 to 200 kPa, with a maximum value of S = 2.6 kPa. -1 .

[0084] comprehensive Figure 6 and Figure 7 This demonstrates that the flexible sensor prepared according to the present invention possesses excellent stress compression and strain tension sensing capabilities. Further sensing performance tests were conducted using the SEBS-CNTs / carbon sponge flexible sensor assembled in Application Example 2. Figure 8 As shown in Figure a, after 10,000 compression cycles at 50% strain, the current remains almost constant, indicating good sensing stability. Figure 8 As shown in b, its response time is only 14.5 ms and its recovery time is 47.6 ms, demonstrating its rapid response capability.

[0085] Experiment Example 5: Sensor Application Verification The compressible piezoresistive flexible stress sensor assembled for use case 2 was validated for sensing applications. The test procedure is as follows: By attaching sensors to the side of the face and wrist pulse points, effective monitoring of various physiological and behavioral signals can be achieved. When the sensor is attached to the side of the face, it can accurately identify subtle facial muscle deformations during different pronunciation processes, such as the pronunciation of "Family" (…). Figure 9 a), "Good morning" ( Figure 9 b) and "Thanks" Figure 9 The sensor clearly distinguishes signals generated by sounds such as "c" and demonstrates good signal resolution capabilities. Furthermore, when the sensor is attached to the wrist pulse point, it can detect approximately 10 pulse beats within 8 seconds, consistent with normal human physiological rhythms. Figure 9 d).

[0086] Although the present invention has been described in detail through the preferred embodiments above, it should be understood that the above description should not be considered as a limitation of the present invention. Various modifications and substitutions to the present invention will be apparent to those skilled in the art after reading the above description. Therefore, the scope of protection of the present invention should be defined by the appended claims.

Claims

1. A method for preparing stretchable and compressible SEBS-CNTs / carbon sponge, characterized in that, The method includes: Melamine sponge is immersed in an aqueous dispersion of carbon nanotubes and impregnated under vacuum conditions to load carbon nanotubes onto the surface of the three-dimensional interconnected framework of the melamine sponge. After drying, CNTs / melamine sponge is obtained. The CNTs / melamine sponge is then subjected to high-temperature annealing in an inert gas atmosphere at a temperature of 1000~1200℃, causing the melamine sponge framework to carbonize and transform into a continuous three-dimensional porous carbon framework, while retaining the carbon nanotubes loaded on its surface, resulting in CNTs / carbon sponge material. The CNTs / carbon sponge material is then placed in a solution containing hydrogenated styrene-butadiene block copolymer (SEBS) for vacuum impregnation and followed by drying and curing. This allows SEBS to form a continuous elastic coating layer on the surface of the CNTs / carbon sponge framework, without completely filling its three-dimensional interconnected channels, thereby obtaining a stretchable and compressible SEBS-CNTs / carbon sponge. The SEBS-CNTs / carbon sponge uses carbonized melamine sponge and carbon nanotubes to form a continuous three-dimensional conductive framework. SEBS acts as an elastic support phase and deforms in tandem with the conductive framework, thus possessing both tensile deformation adaptability and compressive piezoresistive response capability.

2. The preparation method according to claim 1, characterized in that, The mass ratio of carbon nanotubes to SEBS is 1:(5~200).

3. The preparation method according to claim 2, characterized in that, The concentration of the aqueous dispersion of the carbon nanotubes is 1~10 mg / mL; Or / and, the concentration of the SEBS solution is 50~250 mg / mL.

4. The preparation method according to claim 3, characterized in that, The concentration of the aqueous dispersion of the carbon nanotubes is 4~10 mg / mL; Or / and, the concentration of the SEBS solution is 100~200 mg / mL.

5. The preparation method according to any one of claims 1 to 4, characterized in that, In the preparation of the CNTs / melamine sponge, the drying temperature is 100~200℃; Or / and, in the preparation of the CNTs / melamine sponge, the vacuum impregnation time is 30~90 min; Or / and, in the preparation of the CNTs / carbon sponge material, the inert gas is selected from high-purity argon or high-purity nitrogen; Or / and, in the preparation of the SEBS-CNTs / carbon sponge, the impregnation time is 20~40 min; Or / and, in the preparation of the SEBS-CNTs / carbon sponge, the drying temperature is 80~150℃.

6. The stretchable and compressible SEBS-CNTs / carbon sponge obtained by the preparation method according to any one of claims 1 to 5.

7. The application of SEBS-CNTs / carbon sponge as described in claim 6 in flexible sensors.

8. A stretchable piezoresistive flexible strain sensor containing SEBS-CNTs / carbon sponge as described in claim 6.

9. A compressible piezoresistive flexible stress sensor containing SEBS-CNTs / carbon sponge as described in claim 6.

10. The stretchable piezoresistive flexible strain sensor according to claim 8 or the compressible piezoresistive flexible stress sensor according to claim 9, characterized in that, The electrodes are made of copper foil and are disposed at both ends or on the top and bottom surfaces of the SEBS-CNTs / carbon sponge. The electrodes are coated with conductive silver paste and copper wires are placed on them. They are encapsulated using PDMS solution.

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