Mxene-based inorganic / organic hybrid material flexible pressure sensor and application

Abstract

The invention discloses a preparation method and application of a flexible pressure sensor of an Mxene-based low-dimensional inorganic / organic hybrid material. The whole flexible pressure sensor of the Mxene-based low-dimensional inorganic / organic hybrid material is of a sandwich structure and sequentially comprises a protective layer, a modified microstructure layer, a composite sensitive layer, an electrode layer, a modified microstructure layer and a protective layer from top to bottom. A conductive silver paste adhesion interdigital electrode is used as a transmission electrode layer, a cashmere fabric compounded by Mxene and silver nanowires is used as a sensitive layer, abrasive paper is used as a template, PDMS is used as a base material, a modified microstructure layer is obtained through two times of copying, an insulating soft material such as PDMS or resin is selected as a protective layer, and the flexible pressure sensor is obtained through packaging. The preparation method of the flexible pressure sensor of the Mxene-based low-dimensional inorganic / organic hybrid material is simple in processing technology, low in product cost, good in compression characteristic and high in sensitivity, detection of small pressure such as swallowing and pulse of a human body and detection of large pressure such as foot force in different postures can be achieved, and the flexible pressure sensor is suitable for large-scale popularization and application. The method has great application potential in the fields of medical treatment, sports, health protection and the like.

Description

Technical Field

[0001] The present invention relates to a flexible pressure sensor of an Mxene-based low-dimensional inorganic / organic hybrid material and a preparation method and application thereof, belonging to the technical field of force sensors and textile wearable measuring devices. Background Art

[0002] With the rapid development of microelectronics, materials science and nanotechnology, wearable devices have attracted much attention and have shown great potential in medical testing and other fields. As one of the core components of wearable devices, the research and development of pressure sensors has also become a research hotspot. Traditional rigid pressure sensors can no longer meet the needs in the wearable field due to their high hardness, difficulty in fitting with the human body and weak ductility. Flexible pressure sensors, however, have great application potential in human-computer interaction, medical health, intelligent robots and other fields due to their good softness, strong flexibility, high sensitivity and fast response.

[0003] Nowadays, the research on wearable devices has gradually turned to the research on flexible pressure sensors. In order to more accurately detect human body information, higher requirements are also placed on the performance of flexible pressure sensors. The continuous emergence of new materials provides more options for the preparation of flexible pressure sensors. For example, materials such as silicone and polyurethane with high elasticity, wear resistance and aging resistance, as well as sensitive materials such as graphene and carbon nanotubes with piezoresistive effect and piezoelectric effect, provide strong support for improving the performance of sensors.

[0004] At present, the main problem of flexible pressure sensors is that the preparation process is relatively complex, which is not conducive to the large-scale production and application of flexible pressure sensors. In addition, some sensors have problems such as using a single material, incomplete sensitive layer, and no modified microstructure. These problems will cause the flexible pressure sensors to have the shortcomings of large overall volume, low flexibility, high rigidity and weak sensing performance. These shortcomings obviously cannot meet the application in the field of wearable detection. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a flexible sensor with simple process, good compression characteristics and high sensitivity, and apply it to pressure sensing detection, so as to realize the detection of small pressures such as human swallowing and pulse, and large pressures such as foot force in different postures, so as to meet the functionality in the fields of medical treatment, sports, health protection, etc.

[0006] In order to solve the above problems, the present invention provides a Mxene-based inorganic / organic hybrid material flexible pressure sensor, which comprises, from top to bottom, a protective layer, a modified microstructure layer, a composite sensitive layer, an electrode layer, a modified microstructure layer, and a protective layer.

[0007] Preferably, the electrode layer adopts interdigital electrodes and is adhered with conductive silver paste. Each interdigital electrode is connected to the composite sensitive layer through a plurality of branches and is provided with a lead wire to connect to an external signal acquisition device.

[0008] Preferably, the material of the electrode layer is copper foil or silver foil.

[0009] Preferably, the method for preparing the composite sensitive layer comprises the following steps:

[0010] Step 1): using cashmere fabric as a carrier, ultrasonically cleaning with anhydrous ethanol, and then cleaning again with deionized water to remove impurities on the surface of the fabric, and finally drying in an oven;

[0011] Step 2): performing surface modification treatment on the cashmere fabric to roughen its surface;

[0012] Step 3): The cashmere fabric is sequentially immersed in the dispersion of the Mxene two-dimensional nanosheets and the silver nanowires to obtain a Mxene / silver nanowire composite cashmere sensitive layer.

[0013] More preferably, the preparation method of the Mxene two-dimensional nanosheet is a fluorine-containing etching method, a fluorine-free etching method or an organic solvent-assisted intercalation collection method.

[0014] More preferably, the silver nanowires are prepared by chemical reduction, electrochemical or microwave methods.

[0015] Preferably, the method for preparing the modified microstructure layer comprises the following steps:

[0016] Step a): Use sandpaper as a template, clean and dry it, and then fix it with tape;

[0017] Step b): PDMS is coated on the side of the sandpaper having a rough microstructure, and after drying in an oven, it is carefully peeled off with tweezers to obtain a PDMS film having a groove structure opposite to the sandpaper microstructure;

[0018] Step c): PDMS is coated on the surface of the PDMS membrane with the groove structure, and after drying in an oven, it is carefully peeled off with tweezers to obtain a PDMS membrane with the same microstructure as sandpaper.

[0019] Preferably, the protective layer is made of PDMS or resin.

[0020] Preferably, the protective layer, modified microstructure layer, composite sensitive layer, electrode layer, modified microstructure layer, and protective layer are placed into the mold in order, PDMS is poured in, and taken out after drying to obtain a Mxene-based inorganic / organic hybrid material flexible pressure sensor.

[0021] The present invention also provides the application of the above-mentioned Mxene-based inorganic / organic hybrid material flexible pressure sensor in the detection of human swallowing, pulse pressure or pressure detection of foot force in different postures.

[0022] The flexible pressure sensor prepared by the present invention has the advantages of good compression characteristics, high sensitivity, simple processing technology, etc. The flexible pressure sensor based on Mxene low-dimensional inorganic / organic hybrid material can detect small pressures such as human swallowing and pulse, and large pressures such as foot force in different postures. It can be used to detect human health status and body movement, and has great application potential in the fields of medical treatment, sports, health protection, etc.

[0023] The sensing mechanism of the flexible pressure sensor in the present invention is that when external pressure is applied, the modified microstructure layer is pressed down, and the composite sensitive layer is squeezed by the hemispherical structure of the modified microstructure layer and deformed, thereby reducing the resistance value of the composite sensitive layer; when the external pressure is removed, the modified microstructure layer rebounds, the squeezed hemispherical structure rises, and the composite sensitive layer gradually returns to the unpressurized state, and its resistance value gradually increases to the initial value. The magnitude of the applied pressure is detected by the change in the resistance value of the composite sensitive layer.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] (1) The composite sensitive layer of the flexible pressure sensor of Mxene-based low-dimensional inorganic / organic hybrid material adopts cashmere fabric composited with Mxene and silver nanowires. It not only retains the advantages of cashmere fabric itself, but also starts from one-dimensional and two-dimensional pressure-sensitive materials. It takes Mxene nanosheets as the basis, uses this material as the two-dimensional material, and silver nanowires as the one-dimensional material. These two materials are composited on cashmere fabric to obtain a composite sensitive layer with higher sensitivity.

[0026] (2) The flexible pressure sensor of Mxene-based low-dimensional inorganic / organic hybrid materials adds a modified microstructure layer, whose hemispherical structure can amplify the external pressure exerted on the composite sensitive layer. Through structural innovation, the sensitivity of the flexible pressure sensor can be improved by using common materials.

[0027] (3) The present invention innovatively designs a flexible pressure sensor structure of Mxene-based low-dimensional inorganic / organic hybrid materials. The overall structure is a "sandwich structure", which consists of a protective layer, a modified microstructure layer, a composite sensitive layer, an electrode layer, a modified microstructure layer, and a protective layer from top to bottom. The prepared flexible pressure sensor has a simple processing technology, good durability, and strong compression characteristics.

[0028] (4) The interdigitated electrode pairs in the present invention can be prepared by simple processes such as laser direct writing, printing, and template method; the composite sensitive layer can be prepared by dipping, coating, etc. In industry, mature process flows can be used to manufacture highly sensitive flexible pressure sensors. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a schematic diagram of the structure of the Mxene-based flexible pressure sensor provided by the present invention;

[0030] Figure 2 is a process flow chart for modifying the microstructure layer;

[0031] Figure 3 is a process flow chart of a method for preparing a composite sensitive layer;

[0032] Figure 4 This is a diagram showing the foot pressure test results of the Mxene-based inorganic / organic hybrid material flexible pressure sensor of the present invention;

[0033] Figure 5 This is a graph showing the pulse pressure test results of the Mxene-based inorganic / organic hybrid material flexible pressure sensor of the present invention. DETAILED DESCRIPTION

[0034] In order to make the present invention more clearly understood, preferred embodiments are described in detail below with reference to the accompanying drawings.

[0035] Example 1

[0036] This embodiment provides a flexible pressure sensor of a Mxene-based low-dimensional inorganic / organic hybrid material, such as Figure 1 As shown in the figure, the whole structure is a "sandwich structure", which is composed of a protective layer, a modified microstructure layer, a composite sensitive layer, an electrode layer, a modified microstructure layer, and a protective layer from top to bottom. Conductive silver paste is used to adhere the interdigitated electrode as the transmission electrode layer, cashmere fabric composited with Mxene and silver nanowires is used as the sensitive layer, sandpaper is used as the template, PDMS is used as the base material, and the modified microstructure layer is obtained by two replications. Insulating soft materials such as PDMS or resin are selected as the protective layer, and the flexible pressure sensor is encapsulated.

[0037] like Figure 2 As shown, the preparation method of the composite sensitive layer includes the following steps:

[0038] Step 1): using cashmere fabric as a carrier, ultrasonically cleaning with anhydrous ethanol, and then cleaning again with deionized water to remove impurities on the surface of the fabric, and finally drying in an oven;

[0039] Step 2): performing surface modification treatment on the cashmere fabric to roughen its surface;

[0040] Step 3): The cashmere fabric is sequentially immersed in the dispersion of the Mxene two-dimensional nanosheets and the silver nanowires to obtain a Mxene / silver nanowire composite cashmere sensitive layer.

[0041] like Figure 3 As shown, the preparation method of the modified microstructure layer comprises the following steps:

[0042] Step a): Use sandpaper as a template, clean and dry it, and then fix it with tape;

[0043] Step b): PDMS is coated on the side of the sandpaper having a rough microstructure, and after drying in an oven, it is carefully peeled off with tweezers to obtain a PDMS film having a groove structure opposite to the sandpaper microstructure;

[0044] Step c): PDMS is coated on the surface of the PDMS membrane with the groove structure, and after drying in an oven, it is carefully peeled off with tweezers to obtain a PDMS membrane with the same microstructure as sandpaper.

[0045] The assembly method of the above-mentioned Mxene-based inorganic / organic hybrid material flexible pressure sensor is: placing the protective layer, the modified microstructure layer, the composite sensitive layer, the electrode layer, the modified microstructure layer, and the protective layer into the mold in order, pouring PDMS, and taking it out after drying to obtain the Mxene-based inorganic / organic hybrid material flexible pressure sensor.

[0046] The protective layer and modified microstructure layer are made of PDMS material, the composite sensitive layer is Mxene / silver nanowire composite cashmere fabric, and the electrode layer is a copper foil interdigital electrode, which is adhered using conductive silver paste.

[0047] Example 2

[0048] The Mxene-based inorganic / organic hybrid material flexible pressure sensor of Example 1 is placed on the sole to detect different walking postures of the human body. Stepping, walking and running are the most common walking postures in daily life. When the human body walks, the sole of the foot keeps in contact with the sole of the shoe. The flexible pressure sensor can be used to detect the walking speed and intensity, such as Figure 4 shown.

[0049] Example 3

[0050] The Mxene-based inorganic / organic hybrid material flexible pressure sensor of Example 1 is placed and attached to the radial artery of the human wrist to detect the pulse before and after exercise. Figure 5 As shown in the figure, it can be seen that before exercise, the human pulse wave is stable and the pulse rate is slow. After exercise, the human pulse wave fluctuates significantly and the pulse rate accelerates. The results show that the human physiological signals can be detected by the Mxene-based inorganic / organic hybrid material flexible pressure sensor, which has great application potential.

Claims

1. A Mxene-based inorganic / organic hybrid material flexible pressure sensor, characterized in that: From top to bottom, it includes a protective layer, a modified microstructure layer, a composite sensitive layer, an electrode layer, a modified microstructure layer, and a protective layer.

2. The Mxene-based inorganic / organic hybrid material flexible pressure sensor according to claim 1, characterized in that: The electrode layer adopts interdigital electrodes and is adhered by conductive silver paste. Each interdigital electrode is connected to the composite sensitive layer through a plurality of branches and is provided with a lead wire to connect to an external signal collection device.

3. The Mxene-based inorganic / organic hybrid material flexible pressure sensor according to claim 1, characterized in that: The material of the electrode layer is copper foil or silver foil.

4. The Mxene-based inorganic / organic hybrid material flexible pressure sensor according to claim 1, characterized in that: The preparation method of the composite sensitive layer comprises the following steps: Step 1): using cashmere fabric as a carrier, ultrasonically cleaning with anhydrous ethanol, and then cleaning again with deionized water to remove impurities on the surface of the fabric, and finally drying in an oven; Step 2): performing surface modification treatment on the cashmere fabric to roughen its surface; Step 3): The cashmere fabric is sequentially immersed in the dispersion of the Mxene two-dimensional nanosheets and the silver nanowires to obtain a Mxene / silver nanowire composite cashmere sensitive layer.

5. The Mxene-based inorganic / organic hybrid material flexible pressure sensor according to claim 4, characterized in that: The preparation method of the Mxene two-dimensional nanosheet is a fluorine-containing etching method, a fluorine-free etching method or an organic solvent-assisted intercalation collection method.

6. The Mxene-based inorganic / organic hybrid material flexible pressure sensor according to claim 4, characterized in that: The preparation method of the silver nanowires is a chemical reduction method, an electrochemical method or a microwave method.

7. The Mxene-based inorganic / organic hybrid material flexible pressure sensor according to claim 1, characterized in that: The preparation method of the modified microstructure layer comprises the following steps: Step a): Use sandpaper as a template, clean and dry it, and then fix it with tape; Step b): PDMS is coated on the side of the sandpaper having a rough microstructure, and after drying in an oven, it is carefully peeled off with tweezers to obtain a PDMS film having a groove structure opposite to the sandpaper microstructure; Step c): PDMS is coated on the surface of the PDMS membrane with the groove structure, and after drying in an oven, it is carefully peeled off with tweezers to obtain a PDMS membrane with the same microstructure as sandpaper.

8. The Mxene-based inorganic / organic hybrid material flexible pressure sensor according to claim 1, characterized in that: The protective layer is made of PDMS or resin.

9. The Mxene-based inorganic / organic hybrid material flexible pressure sensor according to claim 1, characterized in that: The protective layer, modified microstructure layer, composite sensitive layer, electrode layer, modified microstructure layer and protective layer are placed into the mold in order, PDMS is poured in, and taken out after drying to obtain a Mxene-based inorganic / organic hybrid material flexible pressure sensor.

10. Application of the Mxene-based inorganic / organic hybrid material flexible pressure sensor according to any one of claims 1 to 9 in the detection of human swallowing, pulse pressure or pressure detection of foot force in different postures.

Images