Thermodynamic dual-mode composite sensitive material, preparation method and application thereof

Abstract

The application discloses a thermodynamic dual-mode composite sensitive material, a preparation method and application thereof. The composite sensitive material comprises a matrix, has a three-dimensional porous structure, and comprises a polymer material and a sheet-shaped non-metallic conductive material; and metal oxide nanoparticles are distributed on the surface of the sheet-shaped non-metallic conductive material; wherein the sheet-shaped non-metallic conductive material and the metal oxide nanoparticles are both materials with negative thermoelectric coefficients. The thermodynamic dual-mode composite sensitive material provided by the application integrates pressure sensing and thermoelectric performance, which avoids the problems of complex layout and complex signal transmission of a traditional dual-mode sensor; meanwhile, the pressure sensing and the thermoelectric sensing are not interfered with each other, so that the prepared sensor has the advantages of signal non-interference decoupling, avoidance of wear failure, strong adaptability, non-destructiveness, high safety and the like, can adapt to a higher temperature, and has stable temperature signal output.

Description

Thermodynamic dual-modal composite sensitive materials, their preparation methods and applications Technical Field

[0001] This invention relates to the field of sensitive materials technology, and in particular to a thermodynamic dual-modal composite sensitive material, its preparation method and application. Background Technology

[0002] Sensitive materials can be classified into various sensing methods, such as pressure sensing, displacement sensing, proximity sensing, and temperature sensing.

[0003] One example is the flexible thermoelectric sensor, which measures temperature and converts it into an electrical signal. Combining flexible materials and the thermoelectric effect, it possesses soft, bendable, and deformable properties, allowing it to adapt to various curved and bent surfaces and enabling a wider range of applications. The sensing mechanism is the thermoelectric effect, which refers to the voltage difference generated when the temperature of the contact point between two different materials is uneven. Flexible thermoelectric sensors utilize this effect to measure temperature. They are typically composed of multiple thermoelectric materials, each corresponding to a specific temperature sensitivity. When different areas of the sensor are affected by different temperatures, the voltage difference generated by the various thermoelectric materials reflects the temperature change.

[0004] Flexible thermoelectric sensors have the following characteristics:

[0005] 1. Flexibility and Deformability: Due to the use of flexible materials in its manufacture, the sensor is soft, bendable and stretchable, adapting to different shapes and surfaces.

[0006] 2. Fast response: Flexible thermoelectric sensors have a fast temperature response speed and can monitor temperature changes in real time.

[0007] 3. Wide temperature range: Flexible thermoelectric sensors can operate over a wide temperature range, with applications ranging from low to high temperatures.

[0008] 4. High sensitivity: Flexible thermoelectric sensors can achieve high-sensitivity temperature measurement and have high resolution for temperature changes.

[0009] Flexible thermoelectric sensors have wide applications in many fields, including medical devices, smart wearable devices, and robotics. They can be used in applications such as body temperature monitoring, ambient temperature detection, and industrial temperature control, providing accurate, flexible, and comfortable temperature sensing solutions.

[0010] Unlike thermoelectric sensors, flexible pressure sensors are sensors that measure the pressure applied to their surfaces. Compared to traditional rigid sensors, flexible pressure sensors are soft, bendable, and deformable, allowing them to adapt to surfaces of different shapes and enabling wider applications. The working principle of flexible pressure sensors can be based on various physical effects, including resistance, capacitance, piezoelectricity, and nanomaterials. Based on their working principle and structural characteristics, flexible pressure sensors can be classified into the following categories: resistive pressure sensors, capacitive pressure sensors, piezoelectric pressure sensors, and optical pressure sensors. Among them, flexible piezoresistive sensors are sensors that measure the pressure applied to their surfaces. They are made of flexible materials, possessing soft, bendable, and deformable characteristics, allowing them to adapt to different shapes and surfaces and enabling wider applications. Their working mechanism is based on changes in resistance. When the sensor is subjected to pressure or changes in pressure, the resistance value of the conductive material (such as conductive rubber or carbon nanotubes) changes. This is because the applied pressure alters the electron flow path and contact state within the conductive material, thus affecting the resistance value. By measuring the change in resistance, the magnitude of the pressure applied to the sensor surface can be inferred. Flexible pressure sensors have wide applications in many fields, including health monitoring, human-computer interaction, robotics, and smart wearable devices. Due to their soft, thin, and bendable characteristics, they can be integrated into various curved and bent surfaces to achieve more natural and comfortable pressure measurements.

[0011] The flexible pressure-thermoelectric dual-mode sensor, which combines the above two functions, is a sensor with dual operating modes, capable of simultaneously measuring the pressure and temperature applied to its surface. It combines the characteristics of flexible pressure sensors and thermoelectric sensors, possessing some advantages and disadvantages. The design scheme needs to consider the following aspects:

[0012] Advantages:

[0013] 1. Multimodal Measurement: The flexible pressure-thermoelectric dual-modal sensor can simultaneously measure pressure and temperature, providing more comprehensive tactile information. This is very useful for applications that require comprehensive analysis of contact force and temperature changes on an object.

[0014] 2. High Sensitivity: The flexible pressure-thermoelectric dual-mode sensor has high sensitivity, capable of detecting minute changes in force and temperature. This is crucial for applications requiring precise control and high sensing capabilities.

[0015] 3. Flexibility and Deformability: Due to the use of flexible materials in its manufacture, the sensor is soft, bendable, and stretchable, adapting to different shapes and surfaces. This allows the sensor to adapt to various application scenarios and curved surfaces.

[0016] 4. Real-time response: The flexible pressure-thermoelectric dual-modal sensor has a fast response time, which can monitor and measure changes in pressure and temperature in real time, providing real-time tactile feedback.

[0017] Disadvantages:

[0018] 1. Complex Design: The design of flexible pressure-thermoelectric dual-mode sensors is relatively complex, requiring the integration of pressure and thermoelectric sensors and ensuring that they can work simultaneously and provide accurate measurement results.

[0019] 2. High cost: Due to the integration of multiple sensors and related circuitry, the flexible pressure-thermoelectric dual-modal sensor has a high manufacturing cost. This may limit its widespread adoption in some applications.

[0020] Flexible pressure-thermoelectric dual-modal tactile sensors offer advantages such as multimodal measurement, high sensitivity, flexibility, and real-time response, but also face disadvantages such as complex design and high cost. In the design process, material selection, sensor layout, circuit design, calibration and correction, and application adaptation all need to be comprehensively considered to achieve the optimal balance of performance.

[0021] In addition, with the rapid development of flexible electronic devices in recent years, how to design sensor materials, structures and packaging to solve key problems such as multi-performance interference-free response in the process of flexibility, and to fabricate traditional rigid sensors into new flexible sensor devices with unique structure, high sensitivity and good stability, has also attracted much attention and gradually become one of the important research areas. Summary of the Invention

[0022] To address the shortcomings of existing technologies, the present invention aims to provide a thermodynamic dual-modal composite sensitive material, its preparation method, and its applications.

[0023] To achieve the aforementioned objectives, the technical solution adopted by this invention includes:

[0024] In a first aspect, the present invention provides a thermodynamically dual-modal composite sensing material, comprising a matrix having a three-dimensional porous structure, and including a polymer material and a sheet-like non-metallic conductive material composited with the polymer material, wherein a portion of the sheet-like non-metallic conductive material is exposed on the surface of the pore structure contained in the three-dimensional porous structure; and metal oxide nanoparticles, which are at least distributed on the surface of the sheet-like non-metallic conductive material; wherein both the sheet-like non-metallic conductive material and the metal oxide nanoparticles are materials with negative thermoelectric coefficients.

[0025] Secondly, the present invention also provides a method for preparing a thermodynamic dual-modal composite sensitive material, comprising:

[0026] Provide a precursor solution that contains at least a polymer material and / or a polymer material precursor, a sheet-like non-metallic conductive material, and metal oxide nanoparticles;

[0027] The precursor liquid is freeze-dried to form a matrix with a three-dimensional porous structure from the polymer material and the sheet-like non-metallic conductive material, and the metal oxide nanoparticles are loaded on the surface of the sheet-like non-metallic conductive material.

[0028] The sheet-like non-metallic conductive material and the metal oxide nanoparticles are both materials with negative thermoelectric coefficients. When the precursor is present, the precursor is transformed into a polymer material during the preparation process.

[0029] Thirdly, the present invention also provides a thermodynamic dual-modal sensor device, comprising a sensitive structure, a first electrode, and a second electrode, wherein the sensitive structure is disposed between the first electrode and the second electrode and is in electrical contact with the first electrode and the second electrode respectively; the sensitive structure comprises the aforementioned thermodynamic dual-modal composite sensitive material.

[0030] Furthermore, the first electrode, the sensitive structure, and the second electrode are all flexible thin films, and the first electrode, the sensitive structure, and the second electrode are stacked sequentially.

[0031] Furthermore, it also includes a flexible substrate that covers at least the first electrode and a flexible protective layer that covers at least the second electrode.

[0032] Fourthly, the present invention also provides an interference-free thermo-dual-mode sensing method, which senses the force borne by the thermo-dual-mode composite sensing material by detecting the resistance of the aforementioned thermo-dual-mode composite sensing material.

[0033] And by detecting the thermal response voltage generated by the thermodynamic dual-mode composite sensitive material, the temperature of the thermodynamic dual-mode composite sensitive material is sensed.

[0034] Based on the above technical solution, compared with the prior art, the beneficial effects of the present invention include at least the following:

[0035] The thermodynamic dual-modal composite sensing material provided by this invention is a nanocomposite material that integrates stable pressure sensing and thermoelectric properties. This avoids the problems of complex layout and complex signal transmission of traditional dual-modal sensors, and the material is inexpensive, avoiding the disadvantage of high synthesis cost of dual-modal sensing materials. At the same time, the pressure sensing and thermoelectric sensing of this nanocomposite material are interference-free, which makes the sensor prepared based on this material have advantages such as interference-free decoupling of signals, avoidance of wear failure, strong adaptability, non-destructiveness, and high safety. It can also adapt to high temperatures and has a stable temperature signal output.

[0036] The above description is merely an overview of the technical solution of the present invention. In order to enable those skilled in the art to better understand the technical means of this application and to implement it in accordance with the contents of the specification, the preferred embodiments of the present invention are described below in conjunction with detailed drawings. Attached Figure Description

[0037] Figure 1 is a schematic diagram of the structure of a thermodynamic dual-modal sensor device provided in a typical embodiment of the present invention;

[0038] Figure 2 is a schematic diagram of the preparation process of a thermodynamic dual-modal composite sensitive material provided in a typical embodiment of the present invention;

[0039] Figure 3 is an electron microscope image of the microstructure of the thermodynamic dual-modal composite sensitive material provided in a typical embodiment of the present invention.

[0040] Figure 4 is a piezoresistive performance test diagram of a thermodynamic dual-mode sensor device provided in a typical embodiment of the present invention;

[0041] Figure 5 is a test diagram of the pressure sensing response time and recovery time of a thermodynamic dual-modal sensor device provided in a typical embodiment of the present invention;

[0042] Figure 6 is a piezoresistive cycle performance test diagram of a thermodynamic dual-mode sensor device provided in a typical embodiment of the present invention;

[0043] Figure 7 is a test diagram of the thermoelectric performance and non-contact performance of a thermodynamic dual-modal sensor device provided in a typical embodiment of the present invention;

[0044] Figure 8 is a test diagram of the thermoelectric sensing response time and recovery time of a thermodynamic dual-modal sensor device provided in a typical embodiment of the present invention;

[0045] Figure 9 is a test diagram of the non-contact thermoelectric sensing performance of a thermal dual-modal sensor device provided in a typical embodiment of the present invention;

[0046] Figure 10 is a test diagram showing the effect of temperature on pressure sensing provided by a typical embodiment of the present invention;

[0047] Figure 11 is a test diagram showing the effect of pressure on thermoelectric sensing provided by a typical embodiment of the present invention in a thermodynamic dual-modal sensor device. Detailed Implementation

[0048] In view of the shortcomings of the prior art, the inventors of this invention, through long-term research and extensive practice, have proposed the technical solution of this invention. The following will further explain and illustrate this technical solution, its implementation process, and its principles.

[0049] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and therefore the scope of protection of the invention is not limited to the specific embodiments disclosed below.

[0050] Moreover, relational terms such as “first” and “second” are used merely to distinguish one component or method step from another that has the same name, and do not necessarily require or imply any such actual relationship or order between these components or method steps.

[0051] Specifically, existing dual-modal sensors mainly have the following technical problems:

[0052] 1. Limited Measurement Range: The measurement range of flexible pressure-thermoelectric dual-modal tactile sensors is limited. Specifically, the pressure measurement range may be limited by the sensor's design and materials, while the temperature measurement range depends on the properties of the thermoelectric material. Under certain high-pressure or extreme temperature conditions, the sensor's performance may be limited.

[0053] 2. Cross-interference: Pressure and temperature measurements in flexible pressure-thermoelectric dual-modal tactile sensors are often achieved by sharing a portion of material or circuitry. This can lead to cross-interference between pressure and temperature, meaning that pressure measurements are affected by temperature changes, or vice versa. This cross-interference can result in inaccurate measurement results.

[0054] 3. Complex Manufacturing and Integration: The manufacturing and integration of flexible pressure-temperature multimodal sensors are relatively complex. They typically require the use of different types of materials and components, as well as delicate machining and assembly. This makes the manufacturing and integration of sensors costly and requires specialized manufacturing processes and technologies.

[0055] 4. Stability and Reliability: Flexible pressure-temperature multimodal sensors may face challenges in terms of stability and reliability. Flexible materials and components can be affected by environmental conditions, mechanical stress, and lifespan, potentially leading to performance degradation or failure. Therefore, assessing and improving stability and reliability are important factors to consider when manufacturing and applying such sensors.

[0056] For example, some existing technologies disclose a technical solution that uses flexible electrodes on the upper and lower surfaces of an ion gel layer to form a "sandwich" structure. The pressure and temperature sensitive layers both use the same ion gel material as the sensitive response layer, which has the function of simultaneously monitoring both pressure and temperature. However, in actual measurement, temperature and pressure are still prone to mutual interference. Specifically, in this technical solution, the temperature signal and pressure signal interfere with each other under normal conditions, and the input frequency parameter needs to be specially set to avoid the above interference. It is not possible to use a general and simple measurement method, which brings many limitations and difficulties to the design and application of the device and its circuit.

[0057] In view of this, the present invention aims to design and manufacture a flexible tactile sensor that has stable pressure (or tension)-thermoelectric dual-modal interference-free sensing function. The raw materials are widely available, the cost is low, the manufacturing process is simple and easy, and it can be used for widespread production.

[0058] Based on the above objectives, this invention first provides a thermodynamic dual-modal composite sensing material, comprising a matrix having a three-dimensional porous structure, and including a polymer material and a sheet-like non-metallic conductive material composited with the polymer material, wherein a portion of the sheet-like non-metallic conductive material is exposed on the surface of the pore structure contained in the three-dimensional porous structure; and metal oxide nanoparticles, which are at least distributed on the surface of the sheet-like non-metallic conductive material; wherein both the sheet-like non-metallic conductive material and the metal oxide nanoparticles are materials with negative thermoelectric coefficients.

[0059] As typical application examples of the above technical solutions, PI is used as the polymer material, MXene as the sheet-like non-metallic conductive material, and SrTiO3 as the metal oxide nanoparticles. In the above composite sensitive materials, both MXene and SrTiO3 are materials with negative thermoelectric coefficients. Their combination can enhance the thermoelectric properties of the composite material. PI and MXene form a composite main structure, jointly serving as a flexible substrate. PI provides the framework structure, and MXene is part of the flexible framework. SrTiO3 nanoparticles are attached to the surface of the MXene sheets.

[0060] In the aforementioned composite sensitive material, MXene serves as the main body of the conductive network and possesses a porous structure. When this material deforms under pressure, its resistance changes. The composite of MXene and SrTiO3 nanoparticles generates a temperature-based induced electric field, manifesting externally as a change in thermoelectric voltage. Therefore, this material has a uniformly distributed three-dimensional porous structure. This composite material is a nano-sensitive material integrating pressure sensing and thermoelectric sensing, serving as the sensing material layer of the sensor of this invention. Most importantly, the pressure sensing and thermoelectric sensing are not only integrated but also operate without interference. When the resistance changes under external pressure and the ambient temperature changes simultaneously, the output signal remains almost unchanged before and after the same pressure. Similarly, the thermoelectric signal measures the voltage signal at different temperatures, and when the external pressure on it changes, the voltage signal at the same temperature remains almost unchanged. This is a significant advantage that some existing dual-modal sensitive materials, such as gel films, do not possess.

[0061] Specifically, the pressure sensing of the aforementioned sensitive material is due to the deformation of the device caused by external pressure. As the MXene becomes a conductive path, the number of contact points increases, resulting in a decrease in resistance. Temperature does not increase or decrease the number of conductive path changes, so temperature does not affect the measurement of pressure values. On the other hand, temperature sensing is due to the migration of charge carriers inside the material caused by the temperature difference during temperature testing. Regardless of changes in external pressure, the material is stable, and the number of charge carriers inside is fixed. At a certain temperature, the migration speed of charge carriers is also fixed. Therefore, the open-circuit voltage signal generated by temperature sensing is not affected by pressure. The voltage signal generated by temperature is only related to the temperature difference. Thus, dual-mode measurement of pressure and temperature without interference is achieved.

[0062] Regarding the specific selection of materials and parameters, in some embodiments, the sheet-like non-metallic conductive material includes any one or a combination of two or more of MXene, graphene, transition metal chalcogenides, and boron nitride. Preferably, the transition metal chalcogenides include any one or a combination of two or more of MoS2, VS2, WS2, and WSe2.

[0063] In some embodiments, the metal oxide nanoparticles include any one or a combination of two or more of SrTiO3, BaTiO3, and CuSe.

[0064] In some embodiments, the polymeric material includes any one or a combination of two or more of PI, PDMS, PU, ​​TPE, and TPU.

[0065] Regarding the specific microstructure, in some embodiments, the matrix comprises multiple layers that are stacked on top of each other and have gaps between them to form multiple pore structures.

[0066] In some implementations, the macroscopic morphology of the thermodynamic dual-mode composite sensitive material is a thin film, and the pore structure extends along the thickness direction of the thin film. This extension direction is, for example, the axial direction of the pores. Of course, it is not limited to extending completely perpendicular to the thin film. It is also possible and common to have an appropriate angle of inclination, as long as the general direction tends to be more along the thickness direction. The angle of inclination is not the most critical. The most significant structural feature is that multiple pore structures have the same orderly extension trend.

[0067] In some implementations, the film is a flexible film.

[0068] In some embodiments, the aperture of the hole structure is 0.1-50 μm, and the spacing between the hole structures is 0-50 μm.

[0069] In some embodiments, the mass ratio of the sheet-like non-metallic conductive material to the metal oxide nanoparticles is 5-50:10-100.

[0070] Corresponding to the microstructural characteristics of the aforementioned composite sensitive materials, this invention also provides a method for preparing a thermodynamic dual-modal composite sensitive material, mainly used to form a composite sensitive material with the above-mentioned structural features, comprising the following steps:

[0071] A precursor solution is provided that comprises at least a polymeric material and / or a precursor of the polymeric material, a sheet-like non-metallic conductive material, and metal oxide nanoparticles.

[0072] The precursor liquid is freeze-dried to form a matrix of polymeric material and sheet-like non-metallic conductive material, and the metal oxide nanoparticles are loaded on the surface of the sheet-like non-metallic conductive material.

[0073] The sheet-like non-metallic conductive material and the metal oxide nanoparticles are both materials with negative thermoelectric coefficients. During the preparation process, the precursor is converted into the polymer material.

[0074] In some embodiments, the preparation method may further include:

[0075] The product obtained after freeze-drying is subjected to annealing under a protective atmosphere to convert the precursor into the polymer material. For example, in a preferred embodiment of the invention, the annealing process converts PAA into PI. During this process, PAA can form strong chemical bonds with the MXene surface. After conversion into PI, the resulting overall three-dimensional structure enhances the mechanical strength of the material and improves its resistance to mechanical testing or repeated thermal changes.

[0076] In some embodiments, the annealing treatment is performed at a temperature of 100-500°C for a time of 30-300 minutes.

[0077] In some embodiments, the precursor comprises polyamic acid, and the polymeric material comprises polyimide.

[0078] In some specific examples, the solution ratio is, for example, 1-4 mL of PAA solution, 1-10 mL of MXene (concentration 5 mg / mL), and 10-100 mg of SrTiO3 powder. Of course, the above ratio is the optimal ratio to obtain a more significant measurement signal. Exceeding this ratio range does not mean that it cannot be implemented, but it will affect the signal strength.

[0079] Referring to Figure 1, as a typical application of the above technical solution, the present invention also provides a thermodynamic dual-mode sensor device, which includes a first electrode, a sensitive structure, and a second electrode that are in sequential electrical contact; the sensitive structure includes the thermodynamic dual-mode composite sensitive material provided in any of the above embodiments.

[0080] In some implementations, the first electrode, the sensitive structure, and the second electrode are all flexible thin films, and the first electrode, the sensitive structure, and the second electrode are stacked sequentially.

[0081] In some embodiments, the device further includes a flexible substrate covering at least the first electrode and a flexible protective layer covering at least the second electrode. Specifically, for example, it includes a flexible substrate and / or a flexible protective layer, with the first electrode, the sensitive structure, and the second electrode sequentially stacked on the flexible substrate. The flexible protective layer at least covers the surface of the portion of the second electrode stacked on the sensitive structure and the area of ​​the sensitive structure surface not covered by the second electrode.

[0082] As a specific application method of the above-mentioned device, the present invention also provides an interference-free thermo-mechanical dual-mode sensing method, which includes: sensing the force borne by the thermo-mechanical dual-mode composite sensitive material (or the device structure including the thermo-mechanical dual-mode composite sensitive material, such as a thin film) by detecting the resistance of the above-mentioned thermo-mechanical dual-mode composite sensitive material (or the device containing the material).

[0083] And by detecting the thermal response voltage generated by the thermodynamic dual-mode composite sensitive material, the temperature gradient of the thermodynamic dual-mode composite sensitive material is sensed.

[0084] As typical application examples of the above technical solutions, the embodiments of the present invention mainly illustrate some flexible pressure-thermoelectric dual-modal tactile sensor designs. Generally, the key considerations for the design of flexible pressure-thermoelectric dual-modal tactile sensors are as follows:

[0085] Material Selection: Select materials with good flexibility and thermal conductivity to ensure the sensor can be bent and adapt to different shapes, and achieve effective thermoelectric conduction; Sensor Layout: Consider the sensor layout and structure in the design to ensure good pressure and temperature sensitive areas and avoid mutual interference; Circuit Design: Design appropriate circuits to process and convert the pressure and temperature signals generated by the sensor and provide accurate measurement results; Calibration and Correction: Calibrate and correct the sensor to ensure the accuracy and reliability of the measurement results; Application Adaptation: Adjust the sensor's sensitivity, response speed, and operating range according to the specific application requirements to best meet the application requirements.

[0086] Based on the above design points, this embodiment of the invention mainly illustrates a flexible pressure and thermoelectric multimode sensor based on the PI-SrTiO3@MXene composite sensitive material provided by the above technical solution. Its structure is shown in Figure 1, including: a flexible substrate 5, a sensitive structure 3 (specifically a sensitive layer), a first electrode 4, a second electrode 2, and a flexible protective layer 1. The sensitive layer 3 is a PI-SrTiO3@MXene composite sensitive material and is formed on the surface of the flexible substrate 5. The second electrode 2 and the first electrode 4 are two electrodes led out from the surface of the sensitive structure 3. The flexible protective layer 1 is formed on the surface of the sensitive layer and the second electrode 2 is located on the surface of the sensitive layer, mainly playing the role of at least covering and protecting.

[0087] In the aforementioned device, the flexible pressure-thermoelectric dual-modal tactile sensor uses PI-SrTiO3@MXene nanocomposite material, which has a uniformly distributed three-dimensional porous structure inside. This composite material is a nanosensitive material that integrates pressure sensing and thermoelectric sensing, and serves as the sensing material layer of the sensor of this invention.

[0088] Both the flexible substrate 5 and the flexible protective layer 1 are flexible and adherent. The thickness of the flexible substrate 5 can be, for example, 20-300 μm, and the material of the flexible substrate 5 can be, for example, one or more layers of ethylene-vinyl acetate copolymer, polyvinyl alcohol, polydimethylsiloxane, polyethylene terephthalate, polyimide, and polyethylene. The flexible protective layer 1 can be, for example, polyimide, with a thickness of, for example, 2-100 μm. The first electrode 4 and the second electrode 2 can be made of, for example, metallic copper, and are led out from the surface of the sensitive structure 3 (sensitive layer) by means of silver paste curing. Of course, various other forms of electrical connection methods are also acceptable. These electrodes are connected to the back-end processing circuit board and the high-precision source meter, which can realize instantaneous thermoelectric and piezoresistive responses. Of course, the specific circuit processing can be constructed in conjunction with the resistance-pressure / voltage-temperature response law of the present invention. It is a conventional circuit design that can achieve a certain accuracy of resistance and voltage measurement, and does not need to be elaborated.

[0089] The above examples are merely illustrative and not limited to these examples. For instance, using the sensitive material provided by this invention to prepare non-flexible devices, replacing electrodes made of other metals, adopting non-thin film devices, replacing various different substrates or protective layers, and performing tensile measurements instead of pressure measurements (which also utilizes the resistance changes generated by deformation) are all within the scope of this invention.

[0090] The technical solution of the present invention will be further described in detail below through several embodiments and in conjunction with the accompanying drawings. However, the selected embodiments are only for illustrating the present invention and do not limit the scope of the present invention.

[0091] Example 1

[0092] This embodiment illustrates the preparation process of the SrTiO3@MXene composite sensing material and its specific application in a thermodynamic dual-modal sensor, as shown in Figure 2 and the following detailed steps:

[0093] S1. Diethylene glycol (DEG) and strontium hydroxide octahydrate [Sr(OH)2·8H2O] were added to a three-necked flask and stirred for 3 hours in a water bath at 60°C using a suspended vertical stirrer to ensure uniform dispersion. After 3 hours, tetrabutyl strontium titanate [Ti(OBu)4] was added while stirring and sealing, followed by tetrabutylammonium hydroxide (TBAH). The mixture was then sealed and reacted for 2 hours. The resulting solution was then transferred to a hydrothermal reactor and reacted at 180°C for 24 hours. After the reaction was completed and cooled to room temperature, the solution was transferred to centrifuge tubes and washed repeatedly with deionized water and anhydrous ethanol. Finally, it was dried in a vacuum drying oven at 70°C to obtain pure-phase strontium titanate (SrTiO3).

[0094] S2. Dissolve lithium fluoride in concentrated hydrochloric acid and stir for 10 min. Then slowly add titanium aluminum carbide (Ti3AlC2) to the solution over 30 min. The mixture is then reacted for 24 hours under heating and stirring in a 40°C water bath. The solution is then transferred to a centrifuge tube and washed with deionized water until neutral. After centrifugation, the precipitate is collected using deionized water. The collected dispersion is then centrifuged at high speed to obtain a monolayer precipitate, which is then freeze-dried to obtain large-scale MXene sheets.

[0095] S3. 4'-4'-diaminodiphenyl ether (ODA) was dispersed in dimethylacetamide (DMAc), and 4'-4'-oxydiphthalic anhydride (ODPA) was added under vigorous stirring and stirred for 1 hour. The solution was then washed and solidified with deionized water in multiple portions, and after freezing, it was freeze-dried to obtain polyamic acid (PAA).

[0096] S4. Add 4 mL of polyamic acid (PAA) to deionized water and add triethylamine (TEA) to completely decompose it. Then add 20 mg of SrTiO3 powder and 1 mL of MXene (5 mg / mL dispersion) to the above PAA solution, add deionized water and ultrasonically disperse. After stirring evenly, freeze-dry with liquid nitrogen only, and finally anneal under argon atmosphere for a period of time to obtain a porous sensing material with large, orderly stacked layers. The pore size of the material is distributed in the range of 0.1-50 μm, and the gap between the pores is distributed in the range of 0-50 μm. The microstructure of the obtained thermodynamic dual-mode sensing material is shown in Figure 3. The layered structure arranged along the thickness direction and the porous structure between the layers can be clearly seen.

[0097] S5. The sensitive material (thin film) prepared in step S4 is coated and bonded to a flexible substrate on which a copper electrode layer has been deposited using silver paste, and then dried to form a sensitive layer with a three-dimensional porous structure.

[0098] S6. Coat the surfaces of the electrode layer and the sensitive layer with a material that has good biocompatibility to form a protective layer, so that the protective layer, the electrode layer, the sensitive layer and the flexible substrate are integrated into one.

[0099] S7. Connect the flexible thermoelectric / piezoresistive multimode sensor to the back-end processing circuit board and high-precision source meter to construct a thermoelectric / piezoresistive multimode sensing system for pressure and temperature testing.

[0100] Example 2

[0101] This embodiment illustrates the testing process of the thermodynamic dual-mode sensor device constructed in Embodiment 1 above, as detailed below:

[0102] First, a pressure test was conducted on the device, and the relationship between deformation and resistance was recorded. The results are shown in Figure 4. The pressure and resistance showed a very obvious correlation, and the repeatability was excellent when the same pressure was applied repeatedly. The device exhibited stable piezoresistive sensing performance within a strain range of 5%-50%.

[0103] Figure 5 shows the test results of the pressure response speed of the above-mentioned device. It mainly reflects the response time and recovery time of the piezoresistive signal. It was found that the device can respond to the pressure change in a very short time, which is reflected in the resistance change.

[0104] The device underwent repeated long-term pressure cycle stability tests, including repeated pressure application and removal cycles. The final cycle performance is shown in Figure 6, which demonstrates that the device exhibits excellent pressure cycle capability.

[0105] Regarding temperature testing, Figure 7 shows the temperature response curves for relevant contact tests (e.g., contact with a heating plate) and non-contact tests (e.g., infrared irradiation). It was found that the device can respond promptly when the ambient temperature changes.

[0106] Figure 8 shows the temperature response curve of the device under contact testing, mainly reflecting the response time and recovery time of the thermoelectric signal. In essence, the temperature response of the device is extremely fast, but due to the limitation of the heat transfer rate in the experiment, its temperature changes relatively slowly (especially during cooling, which is natural cooling), which is why the curve changes gradually during cooling.

[0107] Figure 9 shows the comparison of the signal threshold of the thermoelectric signal of the device under non-contact conditions and the resulting responsiveness, which fully demonstrates the excellent thermal sensitivity of the sensitive material provided by the present invention.

[0108] The most significant advantage of the thermodynamic dual-modal composite sensitive material provided by this invention is shown in Figures 10 and 11. Figure 10 illustrates the results of repeated pressure tests on the device made of this material at different temperatures. Specifically, under several fixed pressures, the temperature difference is gradually increased, and the resistance signal stability is observed. It can be seen that when multiple different pressure values ​​are kept constant, the resistance value remains almost unchanged when the temperature changes significantly. This indicates that the temperature has almost no effect on the pressure measurement. In Figure 11, the voltage-temperature correlation (fitted straight line) almost overlaps under different pressure values. Specifically, under several fixed external pressures, the voltage signal changes as the temperature difference gradually increases. It can be seen that regardless of the pressure change, the voltage signal always shows the same linear change with respect to the temperature difference. This also indicates that different pressures have almost no effect on the temperature response.

[0109] This fully demonstrates the significant advantage of the thermodynamic dual-mode sensitive material provided in the embodiments of the present invention: it is interference-free.

[0110] Example 3

[0111] This embodiment is largely the same as Embodiment 1, with the main difference being:

[0112] Using 2 mL of PAA solution, 10 mL of MXene dispersion (concentration 5 mg / mL), and 100 mg of SrTiO3 powder, we can still prepare interference-free thermodynamic dual-mode composite sensitive materials and devices using them. The main difference lies in the signal intensity, but the signal intensity is within an accurately measurable range.

[0113] Example 4

[0114] This embodiment is largely the same as Embodiment 1, with the main difference being:

[0115] Using 1 mL of PAA solution, 5 mL of MXene dispersion (concentration 5 mg / mL), and 50 mg of SrTiO3 powder, we can still prepare interference-free thermodynamic dual-mode composite sensitive materials and devices using them. The main difference lies in the signal intensity, but the signal intensity is within an accurately measurable range.

[0116] Example 5

[0117] This embodiment is largely the same as Embodiment 1, with the main difference being:

[0118] By replacing the polymer material with PU and directly preparing it as an organic solution for freeze-drying, it is still possible to prepare non-interference thermodynamic dual-modal composite sensitive materials and devices that utilize them.

[0119] However, the pressure cycle life of this device decreased to some extent in the later stages of long-term experiments, and its durability was not as good as the network structure formed after annealing in Example 1, but it was still within an acceptable range.

[0120] Example 6

[0121] This embodiment is largely the same as Embodiment 1, with the main difference being:

[0122] By replacing MXene with sheet-like boron nitride and SrTiO3 with BaTiO3, it is still possible to prepare interference-free thermodynamic dual-mode composite sensing materials and devices that utilize them.

[0123] Based on the above embodiments, it is clear that the thermo-modal composite sensing material provided by the embodiments of the present invention is a nanocomposite material that integrates stable pressure sensing and thermoelectric properties. This avoids the problems of complex layout and complex signal transmission of traditional dual-modal sensors, and the material is inexpensive, avoiding the disadvantage of high synthesis cost of dual-modal sensing materials. At the same time, the nanocomposite material has no interference response between pressure sensing and thermoelectric sensing, which makes the sensor prepared based on the material have advantages such as interference-free decoupling of signals, avoidance of sensor wear failure, strong adaptability, non-destructiveness, and safety. It can also adapt to high temperatures and has a stable temperature signal output.

[0124] It should be understood that the above embodiments are merely illustrative of the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A thermodynamic dual-modal composite sensing material, characterized in that, include: A matrix having a three-dimensional porous structure includes a polymer material and a sheet-like non-metallic conductive material composited with the polymer material, wherein a portion of the sheet-like non-metallic conductive material is exposed on the surface of the pore structure contained in the three-dimensional porous structure; and metal oxide nanoparticles, which are at least distributed on the surface of the sheet-like non-metallic conductive material; wherein both the sheet-like non-metallic conductive material and the metal oxide nanoparticles are materials with negative thermoelectric coefficients; the matrix includes multiple sheets, which are stacked on top of each other and have gaps to form multiple pore structures; the pore size of the pore structure is 0.1-50 μm, and the spacing between the pore structures is 1-50 μm; the sheet-like non-metallic conductive material is any one or a combination of two or more of MXene and boron nitride; the metal oxide nanoparticles are any one or a combination of two of SrTiO3 and BaTiO3; and the polymer material is any one or a combination of two of PI and PU.

2. The thermodynamic dual-mode composite sensing material according to claim 1, characterized in that, The macroscopic morphology of the thermodynamic dual-mode composite sensitive material is a thin film, and the porous structure extends along the thickness direction of the thin film.

3. The thermodynamic dual-mode composite sensing material according to claim 2, characterized in that, The film is a flexible film.

4. The thermodynamic dual-mode composite sensing material according to claim 1, characterized in that, The mass ratio of the sheet-like non-metallic conductive material to the metal oxide nanoparticles is 5-50:10-100.

5. The method for preparing the thermodynamic dual-modal composite sensitive material according to any one of claims 1-4, characterized in that, include: A precursor solution is provided, comprising at least a polymeric material and / or a polymeric material precursor, a sheet-like non-metallic conductive material, and metal oxide nanoparticles; the precursor solution is freeze-dried to form a matrix with a three-dimensional porous structure from the polymeric material and the sheet-like non-metallic conductive material, and the metal oxide nanoparticles are loaded on the surface of the sheet-like non-metallic conductive material; wherein the sheet-like non-metallic conductive material and the metal oxide nanoparticles are both materials with negative thermoelectric coefficients, and when the precursor is present, the precursor is converted into a polymeric material during the preparation process.

6. The preparation method according to claim 5, characterized in that, Also includes: The product obtained after freeze-drying is subjected to annealing under a protective atmosphere to at least convert the precursor into the polymer material. The annealing process is carried out at a temperature of 100-500℃ for 30-300 minutes.

7. The preparation method according to claim 6, characterized in that, The precursor is polyamic acid, and the polymer material is polyimide.

8. A thermodynamic dual-mode sensor, characterized in that, The device includes a sensitive structure, a first electrode, and a second electrode. The sensitive structure is disposed between the first electrode and the second electrode and is in electrical contact with the first electrode and the second electrode, respectively. The sensitive structure includes the thermodynamic dual-mode composite sensitive material as described in any one of claims 1-4.

9. The thermodynamic dual-mode sensor device according to claim 8, characterized in that, The sensitive structure is a flexible thin-layer structure, and the first electrode, the sensitive structure, and the second electrode are stacked.

10. The thermodynamic dual-mode sensor device according to claim 9, characterized in that, It also includes a flexible substrate and / or a flexible protective layer, wherein the first electrode, the sensitive structure, and the second electrode are sequentially stacked on the flexible substrate, and the flexible protective layer at least covers the surface of the portion of the second electrode stacked on the sensitive structure and the area of ​​the sensitive structure surface not covered by the second electrode.

11. A non-interference thermodynamic dual-mode sensing method, characterized in that, include: By detecting the resistance of the thermodynamic dual-mode composite sensitive material according to any one of claims 1-4, the force borne by the thermodynamic dual-mode composite sensitive material can be sensed. And by detecting the thermal response voltage generated by the thermodynamic dual-mode composite sensitive material, the temperature gradient of the thermodynamic dual-mode composite sensitive material is sensed.

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