Capacitive pressure and humidity dual-mode sensor and preparation method thereof

Abstract

The invention provides a capacitive pressure and humidity dual-mode sensor and a preparation method thereof, and belongs to the technical field of sensors. A carbon composite material-based sensor is used as a pressure sensing module, and a metal-organic framework compound-based sensor is used as a humidity sensing module. A foam skeleton in the pressure sensing module maintains the mechanical stability of the device, and nanocellulose and reduced graphene oxide enhance the compressive property of the device through a gradient structure induced by self-assembly and gravity, so that the device has good sensitivity and is not interfered by humidity. Hydroxyl groups on organic ligands in the humidity sensing module can react with metal ions through coordination, electrostatic interaction, hydrogen bonds and the like to form a stable MOF structure, so that the stability of metal ion carriers in a metal organic framework is improved, the humidity sensing module is sensitive to humidity, the humidity sensing module has a wide appropriate detection range, and the device can be repeatedly used.

Description

Technical Field

[0001] The present invention belongs to the technical field of sensors, and particularly relates to a capacitive pressure and humidity dual-mode sensor and a preparation method thereof. Background Art

[0002] With the rapid development of embodied intelligence technology, the interaction ability between artificial intelligence and the physical world has been significantly enhanced. Humidity and pressure, as key environmental parameters, not only affect the perception of the external environment by intelligent devices, but also play an important role in the execution efficiency and dynamic feedback of embodied intelligence systems. For example, when an intelligent robot performs tasks in a complex environment, it needs to continuously sense changes in humidity and pressure to optimize path planning and motion strategies; wearable devices provide key data for health assessment and disease warning by monitoring the humidity and pressure conditions around the human body.

[0003] Although traditional humidity sensors can meet some basic applications, they often expose the following problems during long-term operation or in complex environments: the humidity-sensitive materials are vulnerable to temperature fluctuations, dust, and chemical substances, resulting in performance degradation. At the same time, the response hysteresis effect of humidity sensors is particularly obvious in dynamic humidity environments and it is difficult to quickly adapt to large changes in humidity. In extreme humidity conditions (such as low humidity or high humidity), many traditional humidity sensors even fail, leading to insufficient data reliability.

[0004] Traditional pressure sensors are mainly based on piezoresistive, piezoelectric, or capacitive effects. Although they have high sensitivity and response speed, they often fail due to mechanical fatigue under dynamic pressure changes or high mechanical stress conditions. Pressure sensing materials (such as piezoresistive metal films) are easily affected by the humidity environment, resulting in unstable measurement results and even requiring additional environmental shielding measures. In addition, maintaining a wide detection range while maintaining high sensitivity has always been a difficult problem for traditional pressure sensing technologies.

[0005] In many application scenarios that require simultaneous detection of humidity and pressure, traditional separate sensors usually cannot avoid signal cross-interference problems and cannot meet the requirements of embodied intelligence systems for high-precision synchronous detection of multiple parameters. For example, changes in humidity may generate noise in pressure sensing, and pressure changes may also affect the measurement accuracy of humidity sensors. Solving these problems not only requires complex subsequent signal decoupling algorithms, but also may increase the complexity of calculation and real-time processing, and may also lead to a decrease in reliability, limiting the application of sensors in dynamic scenarios.

[0006] Therefore, developing a dual-mode sensor that can efficiently and independently detect changes in humidity and pressure simultaneously in complex dynamic environments is of great significance for promoting the technological development in fields such as embodied intelligence, industrial automation, and medical health monitoring. Summary of the Invention

[0007] The present invention is made to solve the above problems, and aims to provide a capacitive pressure and humidity dual-mode sensor and a preparation method thereof.

[0008] The present invention provides a capacitive pressure and humidity dual-mode sensor, which has the following characteristics. It includes a power supply module, a humidity sensing module, a pressure sensing module, and a data acquisition module. The humidity sensing module and the pressure sensing module are connected in parallel between the positive and negative electrodes of the power supply module. The pressure sensing module includes: a carbon composite active layer, which includes a porous skeleton and a conductive material bonded to the pore surface of the porous skeleton, and the porous skeleton is a non-conductive material; and a first electrode and a second electrode, which are respectively disposed on opposite surfaces of the carbon composite active layer and are respectively connected to the positive and negative electrodes of the power supply module correspondingly. The humidity sensing module includes: a substrate; a pair of interdigital electrodes disposed on the substrate; a pair of flat electrodes disposed on the substrate, and the pair of flat electrodes are respectively connected to the pair of interdigital electrodes by extension correspondingly, and the pair of flat electrodes are respectively connected to the positive and negative electrodes of the power supply module correspondingly; and a metal-organic framework compound thin film layer disposed on the substrate and covering the interdigital electrodes, and the metal-organic framework compound thin film layer is obtained by stacking two-dimensional network topologies layer by layer, and the two-dimensional network topology is obtained by self-assembly of an organic ligand as an organic skeleton and a metal ion as a node. The input port of the data acquisition module is connected to the extended output pin of the first electrode or the second electrode, and the input port of the data acquisition module is also connected to one of the flat electrodes.

[0009] In the capacitive pressure and humidity dual-mode sensor provided by the present invention, it may also have the following characteristics: wherein, the non-conductive material includes any one or more of polyurethane, melamine foam, polystyrene, foamed polyethylene, or latex.

[0010] In the capacitive pressure and humidity dual-mode sensor provided by the present invention, it may also have the following characteristics: wherein, the conductive material includes at least two of self-assembled and stacked nano-cellulose, carbon nanotubes, and reduced graphene oxide, and at least one of nano-cellulose or reduced graphene oxide is included therein, or the conductive material is a one-dimensional conductive material containing carboxyl groups and a two-dimensional conductive material containing hydroxyl groups that are self-assembled and stacked.

[0011] In the capacitive pressure and humidity dual-mode sensor provided by the present invention, it may also have the following characteristics: wherein, the first electrode and / or the second electrode includes any one or more of gold, silver, copper, cadmium, molybdenum, nickel, aluminum, or a conductive carbon electrode.

[0012] In the capacitance-type pressure and humidity dual-mode sensor provided by the present invention, it may further have the following characteristics: wherein, the organic ligand includes any one or more of 5,10,15,20-tetrakis(4-carboxyphenyl)porphyrin, 5,10,15,20-tetrakis(4-hydroxyphenyl)porphyrin, 5,10,15,20-tetrakis(4-aminophenyl)porphyrin, 5,10,15,20-tetrakis(4-pyridyl)porphyrin, trimesic acid, pyromellitic acid or terephthalic acid, and the metal ion corresponding element includes any one or more of Fe, Co, Ni, Cu or Zn.

[0013] In the capacitance-type pressure and humidity dual-mode sensor provided by the present invention, it may further have the following characteristics: wherein, the interdigital electrode and the flat electrode are integrally formed, and the material of the interdigital electrode and / or the flat electrode includes any one or more of indium tin oxide, Au, Ag or Cu.

[0014] In the capacitance-type pressure and humidity dual-mode sensor provided by the present invention, it may further have the following characteristics: wherein, the length of the conductive channel formed by a pair of interdigital electrodes and the metal-organic framework compound thin film layer is 1 mm to 10 mm, and the width is 0.05 mm to 0.1 mm.

[0015] In the capacitance-type pressure and humidity dual-mode sensor provided by the present invention, it may further have the following characteristics: wherein, the data acquisition module includes a data acquisition card or a microcontroller.

[0016] The present invention also provides a preparation method of a capacitance-type pressure and humidity dual-mode sensor, which has the following characteristics for preparing the capacitance-type pressure and humidity dual-mode sensor of any one of the foregoing, including the following steps: S10, loading a conductive material on the pore surface of a porous skeleton to form a carbon composite material active layer; S20, respectively arranging a first electrode and a second electrode on opposite sides of the carbon composite material active layer, and then respectively connecting the first electrode and the second electrode to the positive and negative electrodes of the power supply module in correspondence; S30, self-assembling and stacking layer by layer with an organic ligand and a metal ion on a substrate printed with interdigital electrodes and flat electrodes to obtain a metal-organic framework compound thin film layer; S40, respectively connecting a pair of flat electrodes to the positive and negative electrodes of the power supply module in correspondence; S50, connecting the input port of the data acquisition module to the external output pin of the first electrode or the second electrode, and connecting the input port of the data acquisition module to one of the flat electrodes, and finally preparing a capacitance-type pressure and humidity dual-mode sensor.

[0017] In the preparation method of the capacitive pressure and humidity dual-mode sensor provided by the present invention, the following features may also be included: Among them, in step S10, the hydrothermal reduction temperature is 80°C to 110°C, and the reaction time is 3h to 8h. In step S20, the first electrode and the second electrode are adhered to opposite sides of the carbon composite material active layer through conductive silver paste. In step S30, the organic ligand and metal ions are self-assembled and stacked layer by layer on the substrate through spraying method, spin coating method, drop coating method, scraping method or dip coating method.

[0018] Functions and effects of the invention

[0019] In the present invention, the pressure and humidity dual-mode sensor is respectively composed of a carbon composite material-based sensor as the pressure sensing module and a metal-organic framework compound-based sensor as the humidity sensing module. In the pressure sensing module, the foam skeleton maintains the mechanical stability of the device. Nanocellulose and reduced graphene oxide enhance the compressive performance of the device through self-assembly and gravity-induced gradient structure and have good sensitivity, and are not affected by humidity. In the humidity sensing module, the hydroxyl groups on the organic ligand can react with metal ions through coordination, electrostatic interaction, hydrogen bond and other ways to form a stable MOF structure, thereby enhancing the stability of metal ion carriers in the metal-organic framework, being sensitive to humidity, and having a wide humidity detection range. The device can be reused.

[0020] In the capacitive pressure and humidity dual-mode sensor of the present invention, since the pressure sensing module adopts a foam structure with support and flexibility characteristics, even if there is a response or error in the humidity sensing module of the sensor due to pressure. This unique structural design ensures the complete independence of pressure and humidity signals, and solves the technical problems in traditional dual-mode sensors in terms of signal cross-response and interference. When applying high pressure, the foam material of the pressure sensing module can effectively disperse and bear the pressure, thus avoiding the problems.

[0021] Through the structural and material design of the device, the present invention solves the problem of signal cross-interference in traditional multi-modal sensors, avoids complex decoupling processes, and takes into account the detection range, sensitivity and stability. It realizes the independent and efficient detection of humidity and pressure, provides a reliable sensing basis for the embodied intelligent system, and promotes the development of intelligent environment interaction technology. Description of the drawings

[0022] Figure 1 It is a schematic structural diagram of the pressure sensing module of the capacitive pressure and humidity dual-mode sensor in the embodiment of the present invention;

[0023] Figure 2 It is a schematic structural diagram of the humidity sensing module of the capacitive pressure and humidity dual-mode sensor in the embodiment of the present invention;

[0024] Figure 3Schematic diagram of the stress-strain curve of the carbon composite active layer of the pressure sensing module of sensor 1 in the embodiment of the present invention;

[0025] Figure 4 Response of the humidity sensing module of sensor 1 to humidity in the embodiment of the present invention; Figure 5 Response of the humidity sensing module of sensor 1 to the humidity in human breath in the embodiment of the present invention. Specific embodiments

[0026] In order to make the technical means, creative features, achieved purposes and effects of the present invention easy to understand, the following embodiments will specifically describe a capacitive pressure-humidity dual-mode sensor and its preparation method of the present invention in conjunction with the accompanying drawings.

[0027] <Embodiment>

[0028] Figure 1 Schematic diagram of the structure of the pressure sensing module of the capacitive pressure-humidity dual-mode sensor in the embodiment of the present invention; Figure 2 Schematic diagram of the structure of the humidity sensing module of the capacitive pressure-humidity dual-mode sensor in the embodiment of the present invention.

[0029] As Figure 1 and 2 shown, this embodiment provides a capacitive pressure-humidity dual-mode sensor 100, including a power supply module (not shown in the figure), a pressure sensing module 10, a humidity sensing module 20, and a data acquisition module (not shown in the figure). Among them, the pressure sensing module 10 and the humidity sensing module 20 are connected in parallel at both ends of the positive and negative electrodes of the power supply module.

[0030] The pressure sensing module 10 includes a carbon composite active layer 11, a first electrode 12, and a second electrode 13.

[0031] The carbon composite active layer 11 includes a porous skeleton and a conductive material bonded to the pore surface of the porous skeleton.

[0032] The porous skeleton is a non-conductive material, and the non-conductive material includes any one or more of polyurethane, melamine foam, polystyrene, foamed polyethylene, or latex. (Specifically polyurethane in this embodiment).

[0033] The conductive material bonded to the pore surface of the porous skeleton includes at least 2 of self-assembled stacked nanocellulose, carbon nanotubes, and reduced graphene oxide, and at least one of nanocellulose or reduced graphene oxide is included, or the conductive material is a one-dimensional conductive material containing carboxyl groups and a two-dimensional conductive material containing hydroxyl groups connected by self-assembled stacking.

[0034] The first electrode 12 and the second electrode 13 respectively cover and are disposed on opposite two surfaces of the carbon composite active layer 11, and are respectively connected to the positive and negative electrodes of the power supply module (not shown in the figure). The first electrode 12 and the second electrode 13 include any one or more of gold, silver, copper, cadmium, molybdenum, nickel, aluminum, or a conductive carbon electrode (specifically copper is selected in this embodiment).

[0035] The humidity sensing module 20 includes a substrate 21, a metal-organic framework compound thin film layer 22, a pair of interdigital electrodes 23, and a pair of flat electrodes 24.

[0036] A pair of interdigital electrodes 23 are printed on the substrate 21, and the material thereof is indium tin oxide.

[0037] A pair of flat electrodes 24 are printed on the substrate 21, and the material thereof is indium tin oxide. Moreover, a pair of flat electrodes 24 are respectively integrally and epitaxially connected to a pair of interdigital electrodes 23 (the thicknesses of the flat electrodes 24 and the interdigital electrodes 23 are both 40 nm). A pair of flat electrodes 24 are respectively connected to the positive and negative electrodes of the power supply module (not shown in the figure).

[0038] The metal-organic framework compound thin film layer 22 is disposed on the substrate 21 and covers the interdigital electrodes 23. The metal-organic framework compound thin film layer 22 is obtained by stacking two-dimensional network topologies layer by layer.

[0039] Specifically, in this embodiment, the length of the conductive channel formed by a pair of interdigital electrodes 23 and the metal-organic framework compound thin film layer 22 is 10 mm, and the width is 0.05 mm.

[0040] The two-dimensional network topology is obtained by self-assembly of an organic ligand as an organic framework and metal ions as nodes.

[0041] The organic ligand includes any one or more of 5,10,15,20-tetrakis(4-carboxyphenyl)porphyrin, 5,10,15,20-tetrakis(4-hydroxyphenyl)porphyrin, 5,10,15,20-tetrakis(4-aminophenyl)porphyrin, 5,10,15,20-tetrakis(4-pyridyl)porphyrin, trimesic acid, pyromellitic acid, or terephthalic acid.

[0042] The elements corresponding to the metal ions include any one or more of Fe, Co, Ni, Cu, or Zn.

[0043] The input port of the data acquisition module (not shown in the figure) is connected to the epitaxial output pin of the first electrode 12 or the second electrode 13. The input port of the data acquisition module is also connected to one of the flat electrodes 24.

[0044] Specifically, in this embodiment, the data acquisition module is a data acquisition card or a microcontroller.

[0045] This embodiment also provides a preparation method for a capacitive pressure and humidity dual-mode sensor for preparing the capacitive pressure and humidity dual-mode sensor in this embodiment, including the following steps:

[0046] S10. Prepare the carbon composite active layer 11, including the following sub-steps S11 to S13:

[0047] S11. Ultrasonically clean the porous framework with deionized water and ethanol in sequence, and then put it into an oven for drying.

[0048] S12. Load the conductive material on the pore surface of the porous framework: Adopt the impregnation method, soak the dried porous framework in the precursor solution of the conductive material, extrude it multiple times, then take it out and put it into a polytetrafluoroethylene reaction kettle, drop a small amount of hydrazine hydrate as a reducing agent, then place the reaction kettle in a vacuum oven, and heat it up to 90 °C and keep the reaction for 6 h for hydrothermal reduction.

[0049] When the precursor solution is Tempo nanocellulose-graphene oxide (aq), the conductive material loaded on the porous framework after hydrothermal reduction is nanocellulose and reduced graphene oxide.

[0050] When the precursor solution is carbon nanotube-graphene oxide (aq), the conductive material loaded on the porous framework after hydrothermal reduction is carbon nanotubes and reduced graphene oxide.

[0051] When the precursor solution is Tempo nanocellulose-carbon nanotube (aq), the conductive material loaded on the porous framework after hydrothermal reduction is carbon nanotubes and nanocellulose.

[0052] S13. Take out the sample and put it into a petri dish, dry it at 60 °C for 12 h, and finally obtain a three-dimensional porous framework loaded with the conductive material, that is, the carbon composite active layer 11.

[0053] S20. Prepare the pressure sensing module 10 of the capacitive pressure and humidity dual-mode sensor 100, including the following sub-steps S21 to S23:

[0054] S21. Coat conductive silver paste on the upper surface of the carbon composite active layer 11 and the lower surface of the bottom layer respectively.

[0055] S22. Attach industrial-grade copper electrode sheets to the conductive silver paste on both sides as the first electrode 12 and the second electrode 13 respectively to prepare the pressure sensing module 10.

[0056] S23. Connect the first electrode 12 and the second electrode 13 to the positive and negative poles of the power supply module respectively.

[0057] S30. Prepare the metal-organic framework compound thin film layer 22, including the following sub-steps S31 to S32:

[0058] S31. Clean the substrate 21 printed with the interdigital electrodes 23 and the planar electrodes 24, and the cleaning method can be any one or more of the following 2 methods:

[0059] Method 1: Ultrasonically clean the substrate 21 with acetone and isopropanol for 30 minutes each in sequence, then rinse it with a large amount of deionized water and absolute ethanol, and finally dry the surface of the substrate 21 with a nitrogen gun.

[0060] Method 2: Directly perform Plasma treatment on the surface of the substrate 21.

[0061] S32. Self-assemble and stack layer by layer the organic ligand and metal ions on the substrate 21 printed with the interdigital electrodes 23 and the planar electrodes 24 to obtain the metal-organic framework compound thin film layer 22. The implementation methods include spraying method, spin coating method, drop coating method, scraping method or dip coating method. Specifically, in this embodiment, the spraying method is adopted, including the following steps A01 to A04:

[0062] A01. Place the cleaned substrate 21 in a container containing metal ions (aq).

[0063] Among them, the metal ion concentration in the metal ions (aq) is 1 mM to 5 mM.

[0064] A02. Atomize and spray the organic ligand (aq) on the surface of the metal ions (aq) until a thin film appears. This thin film is the metal-organic framework compound thin film layer 22.

[0065] Among them, the organic ligand concentration in the organic ligand (aq) is 0.1 mM to 0.5 mM.

[0066] A03. After using a syringe to pump out the remaining metal ions (aq) in the container, let the metal-organic framework compound thin film layer 22 naturally land on the substrate 21.

[0067] A04. After the substrate 21 covered with the metal-organic framework compound thin film layer 22 is naturally dried, heat it at 80 °C for 2 hours under vacuum conditions to remove the residual moisture, so that the metal-organic framework compound thin film layer 22 is finally set on the substrate 21 and covers the interdigital electrodes 23.

[0068] S40. Connect the two planar electrodes 24 to the positive and negative electrodes of the power supply module respectively.

[0069] S50. Connect the input port of the data acquisition module to the epitaxial output pin of the first electrode 12 or the second electrode 13, and connect the input port of the data acquisition module to one of the flat electrodes 24, and finally prepare the capacitive pressure and humidity dual-mode sensor 100.

[0070] In this embodiment, six capacitive pressure and humidity dual-mode sensors are prepared by using the above preparation method of the capacitive pressure and humidity dual-mode sensor. They are respectively denoted as sensor 1, sensor 2, sensor 3, sensor 4, comparison sample 1, and comparison sample 2.

[0071] The material selection in the specific preparation process of the above six sensors is shown in Table 1 below.

[0072] Table 1 (Material selection in the specific preparation process of sensor 1, sensor 2, sensor 3, sensor 4, comparison sample 1, and comparison sample 2)

[0073]

[0074] After preparing the above six sensors, in the room temperature and atmospheric environment:

[0075] (1) Use a microcomputer-controlled electronic universal testing machine to test the mechanical properties of the sensor, and at the same time use a precision LCR meter to test the sensing performance of the sensor, and then the capacitance characteristic curve of the pressure sensing module 10 of the sensor can be obtained.

[0076] (2) Use a K-2636 type semiconductor tester, a TH2827C type LCR meter and a related test cavity, and then the capacitance characteristic curve of the humidity sensing module 20 of the sensor can be obtained.

[0077] Figure 3 It is a schematic diagram of the stress-strain curve of the carbon composite active layer of the pressure sensing module of sensor 1 in the embodiment of the present invention.

[0078] As Figure 3 shown, based on the response of the capacitance of the sensor to pressure, use the capacitance change of the sensor as the output signal. Fix the pressure sensing module on the test bench, and connect the sensor to the TH2827C type LCR meter test instrument through a wire. After adjusting the test device to work, test the capacitance signal of the sensor and use the capacitance signal as the electrical signal. After the signal is stable, apply weights of different weights as pressure inputs and record the capacitance characteristic changes of the sensor.

[0079] Apply pressures of 30 Pa, 100 Pa, 1 kPa, 10 k, and 1 MPa respectively. When the sensor is applied with pressure, the capacitance value increases, and when the pressure magnitude remains unchanged, the capacitance value remains stable. When the pressure is unloaded, the capacitance value drops to the starting value. Figure 3It well illustrates the sensitivity of the sensor to pressure changes, can detect a wide range of pressures and has recoverability. Therefore, the capacitance change characteristic of the pressure sensing module can achieve rapid and effective detection of pressure, detect pressures in a wide detection range, and has good recoverability, can be used repeatedly, can achieve static real-time monitoring of pressure, and has a faster response speed.

[0080] By comparing the influence of humidity on the pressure sensing module, it is found that when the humidity changes, the capacitance of the pressure sensing module basically remains unchanged, is insensitive to humidity, and can avoid the cross-response of the pressure sensing module of the capacitive pressure-humidity dual-mode sensor to humidity in the case of simultaneously changing humidity and pressure.

[0081] Figure 4 It is the response of the humidity sensing module of sensor 1 in the embodiment of the present invention to humidity.

[0082] As Figure 4 shown, based on the non-contact response of capacitance to different humidities, the capacitance change of the sensor is used as the output signal. Fix the humidity sensing module on the test bench, connect the sensor to the TH2827C type LCR meter test instrument through wires. After adjusting the test device to work, test the capacitance signal of the sensor and use the capacitance signal as the electrical signal. To ensure the accuracy and stability of the humidity environment, a saturated salt solution humidity bottle is used to construct a standard constant humidity environment. The saturated salt solutions used include calcium chloride (12.1% RH), sodium bromide (61% RH), potassium bromide (82% RH), and potassium sulfate (97.3% RH). The humidity bottle has good airtightness and remains stable in the laboratory constant temperature environment (25°C ± 1°C). Place the sensor into different humidity bottles in turn, record the change of its capacitance value over time until the signal reaches a steady state. Under each humidity condition, measure 3 times repeatedly to verify the repeatability and stability of the sensor.

[0083] Place the humidity sensing module into the saturated salt solutions of calcium chloride (12.1% RH), sodium bromide (61% RH), potassium bromide (82% RH), and potassium sulfate (96% RH) respectively. When placed in the humidity bottles of these saturated salt solutions, the capacitance of the sensor increases, and the capacitance value of the sensor remains stable in the saturated salt solution. When the sensor is away from the humidity bottle, the capacitance value returns to the initial value. Figure 4 It well illustrates the sensitivity of the sensor to different humidities and can achieve non-contact real-time monitoring and discrimination of different humidities.

[0084] Figure 5 It is the response of the humidity sensing module of sensor 1 in the embodiment of the present invention to the humidity in human breath.

[0085] As Figure 5As shown, based on the response of capacitance change to human exhaled humidity, the capacitance change of the sensor is used as the output signal.

[0086] Fix the humidity sensing module on the test bench, and connect the sensor to the TH2827C type LCR meter test instrument through wires. After adjusting the operation of the test device, test the capacitance signal of the sensor, and use the capacitance signal as the electrical signal. After the signal is stable, exhale at a position 1 cm away from the sensor, and record the change of the capacitance characteristics of the sensor.

[0087] When human gas is exhaled, the capacitance of the sensor decreases, and when the blowing time and blowing volume remain unchanged, the capacitance value remains stable. When the blowing stops, the capacitance value returns to the initial value. Figure 5 This well illustrates the sensitivity of the sensor to the humidity of human exhaled gas, can realize non-contact real-time monitoring and discrimination of humidity, and has a fast response speed.

[0088] For sensor 2, through stress tests and pressure response tests, it can be seen that sensor 2 can improve the compressive strength of the pressure sensor, achieve rapid and effective detection of pressure, has good recoverability, can be used repeatedly, can realize static real-time monitoring of pressure, has a faster response speed, and has good recoverability, can be used repeatedly, and can realize detection of a wide range of pressures.

[0089] For sensor 3, through stress tests and pressure response tests, it can be seen that sensor 3 can improve the compressive strength of the pressure sensor, achieve rapid and effective detection of pressure, has good recoverability, can be used repeatedly, can realize static real-time monitoring of pressure, has a faster response speed, and has good recoverability, can be used repeatedly, and can realize detection of a wide range of pressures.

[0090] For sensor 4, through humidity response tests, it can be seen that sensor 4 can achieve effective detection of humidity, has a large detection range, and has good recoverability and can be used repeatedly.

[0091] For comparative sample 1, through stress tests and pressure response tests, it can be seen that the sensor based on reduced graphene oxide has a high sensitivity, but has a low detection upper limit (<0.1 MPa) and a low compressive strength.

[0092] For comparative sample 2, through stress tests and pressure response tests, it can be seen that the sensor based on nanocellulose has a high compressive strength but poor sensitivity.

[0093] Functions and effects of the embodiments

[0094] In this embodiment, through the design of a capacitive pressure and humidity dual-mode sensor, the problem of signal cross-response of traditional multimodal sensors is solved. A completely independent pressure sensing module and humidity sensing module are adopted, and through material selection and structural optimization, it is ensured that the signals of the two do not interfere with each other. The pressure module uses a composite porous foam material, whose characteristics can achieve precise response in a dynamic high-pressure environment and completely shield the interference of humidity changes; the humidity module uses a metal-organic framework compound, whose characteristics ensure a highly sensitive response to humidity changes. Since the pressure sensing module adopts a foam structure with supportive and flexible characteristics, even the response or error of the sensor humidity sensing module caused by pressure can be compensated. This unique structural design ensures the complete independence of pressure and humidity signals, solves the problem of signal cross-response in traditional dual-mode sensors, avoids complex decoupling processes, and takes into account the detection range, sensitivity, and stability.

[0095] In this embodiment, through the design of a capacitive pressure and humidity dual-mode sensor, the output signal is directly the change in electrical signals such as capacitance or resistance, without the need for special additional devices to convert a certain physical quantity or chemical quantity into an electrical signal for measurement. Therefore, the structure is simple, which is conducive to miniaturization and portability.

[0096] A capacitive pressure and humidity dual-mode sensor in this embodiment is simple to manufacture and convenient to use, can achieve wide-range pressure detection, and can also detect wide-range humidity changes, has good sensitivity, and has excellent cyclic stability.

[0097] Those skilled in the art of this industry should understand that the present invention is not limited by the above embodiments. What is described in the above embodiments and the specification only illustrates the principle of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed. The scope of protection claimed by the present invention is defined by the appended claims and their equivalents.

Claims

1. A capacitive pressure and humidity dual-mode sensor, characterized in that, It includes a power module, a humidity sensing module, a pressure sensing module and a data acquisition module. The humidity sensing module and the pressure sensing module are connected in parallel between the positive and negative electrodes of the power module. The pressure sensing module includes: A carbon composite active layer, including a porous skeleton and a conductive material bonded to the pore surface of the porous skeleton. The porous skeleton is a non-conductive material; and A first electrode and a second electrode, which are respectively disposed on opposite surfaces of the carbon composite active layer and are respectively connected to the positive and negative electrodes of the power module correspondingly. The humidity sensing module includes: A substrate; A pair of interdigital electrodes disposed on the substrate; A pair of flat electrodes disposed on the substrate. One of the pair of flat electrodes is respectively connected to the corresponding extension of one of the pair of interdigital electrodes. One of the pair of flat electrodes is respectively connected to the positive and negative electrodes of the power module correspondingly; and A metal-organic framework compound thin film layer disposed on the substrate and covering the interdigital electrodes. The metal-organic framework compound thin film layer is obtained by stacking two-dimensional network topologies layer by layer. The two-dimensional network topology is obtained by self-assembly of an organic ligand as an organic skeleton and metal ions as nodes. The input port of the data acquisition module is connected to the extension output pin of the first electrode or the second electrode. The input port of the data acquisition module is also connected to one of the flat electrodes.

2. The capacitive pressure and humidity dual-mode sensor according to claim 1, wherein: Among them, The non-conductive material includes any one or more of polyurethane, melamine foam, polystyrene, foamed polyethylene or latex.

3. The capacitive pressure and humidity dual-mode sensor according to claim 1, wherein: Among them, The conductive material includes at least two of self-assembled stacked nano-cellulose, carbon nanotubes and reduced graphene oxide, and at least one of nano-cellulose or reduced graphene oxide is included therein. Or the conductive material is a one-dimensional conductive material containing carboxyl groups and a two-dimensional conductive material containing hydroxyl groups connected by self-assembly stacking.

4. The capacitive pressure and humidity dual-mode sensor according to claim 1, wherein: Among them, The first electrode and / or the second electrode includes any one or more of gold, silver, copper, cadmium, molybdenum, nickel, aluminum or a conductive carbon electrode.

5. The capacitive pressure and humidity dual-mode sensor according to claim 1, wherein: Among them, The organic ligand includes any one or more of 5,10,15,20-tetrakis(4-carboxyphenyl)porphyrin, 5,10,15,20-tetrakis(4-hydroxyphenyl)porphyrin, 5,10,15,20-tetrakis(4-aminophenyl)porphyrin, 5,10,15,20-tetrakis(4-pyridyl)porphyrin, trimesic acid, pyromellitic acid or terephthalic acid. The metal ion corresponding element includes any one or more of Fe, Co, Ni, Cu or Zn.

6. The capacitive pressure and humidity dual-mode sensor according to claim 1, wherein: Among them, The interdigital electrodes and the flat electrodes are integrally formed. The material of the interdigital electrode and / or the planar electrode includes any one or more of indium tin oxide, Au, Ag, or Cu.

7. The capacitance-type pressure and humidity dual-mode sensor according to claim 1, wherein: Among them, The length of the conductive channel formed by a pair of the interdigital electrodes and the metal-organic framework compound thin film layer is 1 mm to 10 mm, and the width is 0.05 mm to 0.1 mm.

8. The capacitance-type pressure and humidity dual-mode sensor according to claim 1, wherein: Among them, The data acquisition module includes a data acquisition card or a microcontroller.

9. The preparation method of the capacitive pressure and humidity dual-mode sensor according to any one of claims 1 to 8, characterized in that It includes the following steps: S10. Loading the conductive material on the pore surface of the porous framework to form the carbon composite active layer; S20. After respectively arranging a first electrode and a second electrode on opposite sides of the carbon composite active layer, connecting the first electrode and the second electrode to the positive and negative electrodes of the power supply module respectively; S30. Using the organic ligand and the metal ions to self-assemble and stack layer by layer on the substrate printed with the interdigital electrode and the planar electrode to obtain the metal-organic framework compound thin film layer; S40. Connecting a pair of the planar electrodes to the positive and negative electrodes of the power supply module respectively; S50. Connecting the input port of the data acquisition module to the extended output pin of the first electrode or the second electrode, and connecting the input port of the data acquisition module to one of the planar electrodes, and finally preparing the capacitance-type pressure and humidity dual-mode sensor.

10. The method for preparing the capacitance-type pressure and humidity dual-mode sensor according to claim 9, wherein: Among them, In step S10, the hydrothermal reduction temperature is 80°C to 110°C, and the reaction time is 3 h to 8 h. In step S20, the first electrode and the second electrode are adhered to opposite sides of the carbon composite active layer by conductive silver paste. In step S30, the self-assembly and layer-by-layer stacking of the organic ligand and the metal ions on the substrate are realized by spraying method, spin coating method, drop coating method, scraping method or dip coating method.

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