Multi-layer fiber membrane flexible pressure sensor based on surface energy gradient and preparation method thereof

Abstract

The invention belongs to the technical field of flexible pressure sensors, and discloses a multilayer fiber membrane flexible pressure sensor based on surface energy gradient and a preparation method thereof. The structure sequentially comprises a top flexible substrate, a top electrode layer, a first sensitive layer, a second sensitive layer, a third sensitive layer, a bottom electrode layer and a bottom flexible substrate. According to the preparation method, a polymer film and a patterned metal film are selected as a flexible substrate and an electrode respectively, a fiber fabric is used as a sensitive layer carrier, Mxene and silver nanowires are used as sensitive materials, and a dielectric barrier discharge (DBD) technology is used for carrying out surface treatment on the fabric. Through the technology, the surface of the fabric has different roughness and chemical components so as to obtain different surface energy, so that the adhesive force of the sensitive material on the surface of the fabric can be increased, and the sensitivity and the detection range of the pressure sensor can be improved. The flexible pressure sensor prepared by the invention is simple in structure, simple and convenient to prepare and low in cost, and has great application potential.

Description

Technical Field

[0001] The present invention belongs to the technical field of flexible pressure sensors, and in particular, relates to a multi-layer fiber membrane flexible pressure sensor based on surface energy gradient and a preparation method thereof. Background Art

[0002] Pressure sensors are a type of sensor that converts external force into electrical signals. However, traditional pressure sensors are usually made of rigid materials and have the characteristics of being heavy, large, and not easy to deform, which limits the scope of use of pressure sensors. Flexible pressure sensors are sensors that mimic the natural perception of human skin. Because of their good mechanical flexibility, they can achieve intelligence, portability, and wearability in various complex shapes and surface environments, which has attracted widespread attention in the fields of electronic skin, soft robots, wearable health monitoring, and human-machine interfaces. Sensitivity and range are key performance indicators of flexible pressure sensor devices. However, currently, flexible pressure sensors mainly adopt a "sandwich" structure, which consists of two electrode layers with a sensitive layer sandwiched between them. This structure has poor compressibility and is difficult to maintain high sensitivity in a wide linear pressure range, which greatly limits the scope of application of flexible pressure sensors.

[0003] The optimization concept of flexible pressure sensors is also mainly based on the idea of ​​structural optimization and assisted embedding of sensitive materials. For example, various microstructure arrays (such as bump arrays, micropillar arrays, etc.) are prepared in the sensitive layer and assisted in embedding various nano and micro / nano composite materials, so as to increase the contact area of ​​the device sensing area to increase the amount of change of the electrical signal with pressure, thereby improving the sensitivity of the device and expanding the sensor detection range. However, the preparation of microstructure arrays is complex and costly; and in the study, it was found that nano and micro / nano composite materials have poor bonding with the matrix material, and are easy to fall off from the sensitive layer matrix during use, affecting the performance of the sensor. Therefore, it is urgent to explore a new paradigm of sensor design and preparation strategy to achieve the goal of flexible pressure sensors with simple structure, convenient preparation, low cost, stable performance, wide range and high sensitivity. Summary of the invention

[0004] In view of the defects in the prior art, the present invention provides a multi-layer fiber membrane flexible pressure sensor based on surface energy gradient and a method for preparing the same. The method proposes a new type of flexible pressure sensor with a surface energy gradient and a multi-layer stacked structure and a method for preparing the same, which has the advantages of simple structure, convenient preparation, stable performance, wide range, high sensitivity, etc.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] A multi-layer fiber membrane flexible pressure sensor based on surface energy gradient, the structure of the flexible pressure sensor from top to bottom is a top flexible substrate, a top electrode layer, a first sensitive layer, a second sensitive layer, a third sensitive layer, a bottom electrode layer, and a bottom flexible substrate.

[0007] The top flexible substrate and the bottom flexible substrate are both made of polymer films; the top electrode layer and the bottom electrode layer are patterned conductive metal films; the first sensitive layer, the second sensitive layer and the third sensitive layer are carried by fiber fabrics and embedded with different contents of nano silver wires and Mxene.

[0008] The top electrode layer is deposited on the top flexible substrate surface, and the bottom electrode layer is deposited on the bottom flexible substrate surface.

[0009] The first sensitive layer, the second sensitive layer and the third sensitive layer are stacked in sequence and placed between the top electrode layer and the bottom electrode layer.

[0010] The top electrode layer and the bottom electrode layer are stacked face to face and disposed between the top flexible substrate and the bottom flexible substrate.

[0011] According to another aspect of the present invention, a method for preparing a multilayer fiber membrane flexible pressure sensor based on surface energy gradient is provided, comprising the following steps:

[0012] Step 1: Place the fiber fabric in an ultrasonic cleaning machine and clean it with anhydrous ethanol and deionized water respectively, take it out and place it in an oven to dry;

[0013] Step 2: surface treating the fiber fabric obtained in step 1 by using dielectric barrier discharge (DBD) technology;

[0014] Step 3: soaking the fiber fabric prepared in step 2 in a nano silver wire solution, and then drying the fiber fabric in an oven to obtain a fiber fabric embedded with nano silver wires;

[0015] Step 4: soaking the fiber fabric embedded with nano silver wires in step 3 in a MXene dispersion, and then drying it in an oven to obtain a fiber fabric embedded with nano silver wires and MXene;

[0016] Step 5: Cut the fiber fabric embedded with nano silver wires and Mxene obtained in step 4 into the same size as the top flexible substrate and the bottom flexible substrate, and use them as the sensitive layer; repeat steps 1 to 4 to obtain fiber fabrics embedded with different contents of nano silver wires and Mxene as the first sensitive layer, the second sensitive layer, and the third sensitive layer respectively;

[0017] Step six: stack the first sensitive layer, the second sensitive layer, and the third sensitive layer obtained in step five into a multilayer structure in the order of increasing DBD treatment time, and place them between the top electrode layer and the bottom electrode layer. Finally, use the top flexible substrate and the bottom flexible substrate for packaging to make a multilayer fiber membrane flexible pressure sensor based on surface energy gradient.

[0018] Preferably, the fiber fabric in step 1 is polyester fiber fabric or cotton fabric with a thickness of about 1 mm.

[0019] Preferably, the temperature of the oven in step 1, step 3 and step 4 is set to 60° C., and the drying time is 30 minutes; and the soaking time in step 3 and step 4 is 12 hours.

[0020] Preferably, after one surface of the fiber fabric is treated with DBD in step 2, it is turned over to treat the other surface to ensure that both sides of the fiber fabric are treated; and the total DBD surface treatment time of the first sensitive layer, the second sensitive layer and the third sensitive layer in steps 2 and 5 is 1 minute, 3 minutes and 5 minutes respectively.

[0021] Beneficial effects of the present invention:

[0022] 1. The present invention designs a flexible pressure sensor composed of multi-layer stacked fiber membranes based on surface energy gradient. Different surface energies of the fiber membrane surface can be used to adsorb different amounts of micro / nano sensitive materials, and a sensitive layer can be formed by simple stacking, so it has the advantages of novel structure and simple composition.

[0023] 2. The present invention adopts DBD surface treatment technology to change the surface energy of the fiber membrane, which can simultaneously change the chemical composition and micro-nano structure of the fiber membrane surface, which can not only increase the contact area of ​​the device sensing area, but also increase the bonding force between the micro / nano sensitive material and the fiber membrane, effectively improving the performance of the flexible pressure sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The present invention will be further described below in conjunction with the accompanying drawings.

[0025] Figure 1 This is a schematic diagram of the structure of a flexible pressure sensor composed of multi-layer stacked fiber membranes based on surface energy gradient according to the present invention.

[0026] Figure 2 The present invention is a flow chart of the preparation process of a flexible pressure sensor composed of multi-layer stacked fiber membranes based on surface energy gradient.

[0027] Figure 3 1 and 2 are scanning electron microscope micrographs of the sensitive layers in one example of the present invention (a) before treatment and after DBD treatment for (b) 1 minute, (c) 3 minutes, and (d) 5 minutes, respectively.

[0028] Figure 4 Figure 2 is the sensitivity of the flexible pressure sensor with and without surface energy gradient in an example of the present invention.

[0029] In the figure:

[0030] U1-top flexible substrate, U2-top electrode layer, S1-first sensitive layer, S2-second sensitive layer, S3-third sensitive layer, B1-bottom flexible substrate, B2-bottom electrode layer. DETAILED DESCRIPTION

[0031] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] like Figure 1 , Figure 2 As shown, a flexible pressure sensor composed of a multi-layer stacked fiber membrane based on a surface energy gradient, the structure of the flexible pressure sensor from top to bottom is a top flexible substrate U1, a top electrode layer U2, a first sensitive layer S1, a second sensitive layer S2, a third sensitive layer S3, a bottom flexible substrate B1, and a bottom electrode layer B2.

[0033] The top flexible substrate U1 and the bottom flexible substrate B1 are made of polymer film; the top electrode layer U2 and the bottom electrode layer B2 are patterned conductive metal films; the first sensitive layer S1, the second sensitive layer S2, and the third sensitive layer S3 are based on fiber fabrics and are embedded with different contents of nano silver wires and Mxene.

[0034] The top electrode layer U2 is deposited on the surface of the top flexible substrate U1 , and the bottom electrode layer B2 is deposited on the surface of the bottom flexible substrate B1 .

[0035] The first sensitive layer S1, the second sensitive layer S2, and the third sensitive layer S3 are stacked in sequence and placed between the top electrode layer U2 and the bottom electrode layer B2.

[0036] The top electrode layer U2 and the bottom electrode layer B2 are stacked face to face and placed between the top flexible substrate U1 and the bottom flexible substrate B1.

[0037] According to another aspect of the present invention, a method for preparing a multilayer fiber membrane flexible pressure sensor based on surface energy gradient is provided, comprising the following steps:

[0038] Step 1: Place the fiber fabric in an ultrasonic cleaning machine and clean it with anhydrous ethanol and deionized water respectively, take it out and place it in an oven to dry;

[0039] Step 2: surface treating the fiber fabric obtained in step 1 by using dielectric barrier discharge (DBD) technology;

[0040] Step 3: soaking the fiber fabric prepared in step 2 in a nano silver wire solution, and then drying the fiber fabric in an oven to obtain a fiber fabric embedded with nano silver wires;

[0041] Step 4: soaking the fiber fabric embedded with nano silver wires in step 3 in Mxene, and then drying it in an oven to obtain a fiber fabric embedded with nano silver wires and Mxene;

[0042] Step 5: Cut the fiber fabric embedded with nano silver wires and Mxene obtained in step 4 into the same size as the top flexible substrate U1 and the bottom flexible substrate B1, and use them as the sensitive layer; repeat steps 1 to 4 to obtain fiber fabrics embedded with nano silver wires and Mxene at different contents as the first sensitive layer S1, the second sensitive layer S2, and the third sensitive layer S3 respectively;

[0043] Step six: stack the first sensitive layer S1, the second sensitive layer S2, and the third sensitive layer S3 obtained in step five into a multilayer structure in the order of increasing DBD treatment time, and place them between the top electrode layer U2 and the bottom electrode layer B2. Finally, use the top flexible substrate U1 and the bottom flexible substrate U2 for packaging to make a multilayer fiber membrane flexible pressure sensor based on surface energy gradient.

[0044] As a preferred embodiment, the fiber fabric in step 1 is polyester fiber fabric or cotton fabric with a thickness of about 1 mm.

[0045] As a preferred embodiment, the temperature of the oven in step 1, step 3 and step 4 is set to 60° C., and the drying time is 30 minutes; the soaking time in step 3 and step 4 is 12 hours.

[0046] As a preferred embodiment, after one surface of the fiber fabric is subjected to DBD surface treatment in step 2, it is turned over to treat the other surface, ensuring that both surfaces of the fiber fabric are treated; and the total DBD surface treatment time of the first sensitive layer S1, the second sensitive layer S2, and the third sensitive layer S3 in step 2 and step 5 is 1 minute, 3 minutes, and 5 minutes, respectively. Figure 3 The roughness of the first sensitive layer S1, the second sensitive layer S2, and the third sensitive layer S3 increases successively, and the sensitive material attached to the surface of the fiber fabric also increases successively.

[0047] As a preferred embodiment, in step five, the sizes of the first sensitive layer S1, the second sensitive layer S2, and the third sensitive layer S3 after cutting are all 1 cm × 2 cm; in step six, the top electrode layer U2 and the bottom electrode layer B2 are both made of patterned copper film, and the top flexible substrate U1 and the bottom flexible substrate U2 are made of polyimide film.

[0048] like Figure 4 ,Compared to the multilayer fiber membrane flexible pressure sensor without surface energy gradient, the multilayer fiber membrane flexible pressure sensor with surface energy gradient prepared after DBD treatment has better sensitivity and detection range.

[0049] In other embodiments, flexible pressure sensors with different sensing properties can be prepared by selecting different DBD processing times, the number of sensitive layer stacking, the type of sensitive materials, etc.

[0050] The above specific implementation method part specifically introduces the analytical method involved in the present invention. It should be noted that the above introduction is only to help those skilled in the art better understand the method and ideas of the present invention, rather than limiting the relevant content. Without departing from the principle of the present invention, those skilled in the art may also make appropriate adjustments or modifications to the present invention, and the above adjustments and modifications shall also fall within the scope of protection of the present invention.

Claims

1. A multilayer fiber membrane flexible pressure sensor based on surface energy gradient, characterized in that: The structures of the flexible pressure sensor from top to bottom are a top flexible substrate, a top electrode layer, a first sensitive layer, a second sensitive layer, a third sensitive layer, a bottom electrode layer, and a bottom flexible substrate.

2. A multilayer fiber membrane flexible pressure sensor based on surface energy gradient according to claim 1, characterized in that: The top flexible substrate and the bottom flexible substrate are both made of polymer films; the top electrode layer and the bottom electrode layer are patterned conductive metal films; the first sensitive layer, the second sensitive layer and the third sensitive layer are carried by fiber fabrics and embedded with different contents of nano silver wires and Mxene.

3. The multilayer fiber membrane flexible pressure sensor based on surface energy gradient according to claim 1 is characterized in that: The top electrode layer is deposited on the top flexible substrate surface, and the bottom electrode layer is deposited on the bottom flexible substrate surface.

4. The multilayer fiber membrane flexible pressure sensor based on surface energy gradient according to claim 1 is characterized in that: The top electrode layer and the bottom electrode layer are stacked face to face and disposed between the top flexible substrate and the bottom flexible substrate.

5. A method for preparing a multilayer fiber membrane flexible pressure sensor based on surface energy gradient according to claim 1, characterized in that: The following steps are involved: Step 1: Place the fiber fabric in an ultrasonic cleaning machine and clean it with anhydrous ethanol and deionized water respectively, take it out and place it in an oven to dry; Step 2: surface treating the fiber fabric obtained in step 1 by using dielectric barrier discharge technology; Step 3: soaking the fiber fabric prepared in step 2 in a nano silver wire solution, and then drying the fiber fabric in an oven to obtain a fiber fabric embedded with nano silver wires; Step 4: soaking the fiber fabric embedded with nano silver wires in step 3 in a MXene dispersion, and then drying it in an oven to obtain a fiber fabric embedded with nano silver wires and MXene; Step 5: Cut the fiber fabric embedded with nano silver wires and Mxene obtained in step 4 into the same size as the top flexible substrate and the bottom flexible substrate, and use it as a sensitive layer; Repeat steps 1 to 4 to obtain fiber fabrics embedded with different contents of nano silver wires and Mxene as the first sensitive layer, the second sensitive layer, and the third sensitive layer respectively; Step six: stack the first sensitive layer, the second sensitive layer, and the third sensitive layer obtained in step five into a multilayer structure in the order of increasing DBD treatment time, and place them between the top electrode layer and the bottom electrode layer. Finally, use the top flexible substrate and the bottom flexible substrate for packaging to make a multilayer fiber membrane flexible pressure sensor based on surface energy gradient.

6. The method for preparing a multilayer fiber membrane flexible pressure sensor based on surface energy gradient according to claim 5, characterized in that: The fiber fabric in step 1 is polyester fiber fabric or cotton fabric with a thickness of 1 mm.

7. The method for preparing a multilayer fiber membrane flexible pressure sensor based on surface energy gradient according to claim 5, characterized in that: In step 1, step 3 and step 4, the temperature of the oven is set to 60° C., and the drying time is 30 minutes; and the soaking time in step 3 and step 4 is 12 hours.

8. The method for preparing a multilayer fiber membrane flexible pressure sensor based on surface energy gradient according to claim 5, characterized in that: In step 2, after one surface of the fiber fabric is treated with DBD, it is turned over to treat the other surface so that both sides of the fiber fabric are treated; and the total DBD surface treatment time of the first sensitive layer, the second sensitive layer, and the third sensitive layer in steps 2 and 5 is 1 minute, 3 minutes, and 5 minutes, respectively.

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