A multilayer fiber membrane flexible pressure sensor based on surface energy gradient and a preparation method thereof

Abstract

The application 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 is in turn 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.The preparation method selects a polymer film and a patterned metal film as the flexible substrate and the electrode respectively, selects a fiber fabric as the sensitive layer carrier, selects Mxene and nano silver wire as the sensitive material, and performs surface treatment on the fabric by using dielectric barrier discharge (DBD) technology.Through the technology, the surface of the fabric has different roughness and chemical components to obtain different surface energy, which can not only increase the adhesion of the sensitive material on the surface of the fabric, but also improve the sensitivity and detection range of the pressure sensor.The flexible pressure sensor prepared by the application has the advantages of simple structure, simple preparation and low cost, and has great application potential.

Description

Technical Field

[0001] This invention belongs to the field of flexible pressure sensor technology, specifically, it relates to a multilayer fiber membrane flexible pressure sensor based on surface energy gradient and its preparation method. Background Technology

[0002] Pressure sensors are a type of sensor that converts external force into an electrical signal. However, traditional pressure sensors are usually made of rigid materials, resulting in heavy weight, large size, and resistance to deformation, thus limiting their application range. Flexible pressure sensors, which mimic the natural sensing ability of human skin, possess excellent mechanical flexibility and can achieve intelligence, portability, and wearability in various complex shapes and surface environments. This has attracted widespread attention in fields such as electronic skin, soft robots, wearable health monitoring, and human-machine interfaces. Sensitivity and range are key performance indicators for flexible pressure sensors. However, current flexible pressure sensors mainly adopt a "sandwich" structure, consisting of two electrode layers with a sensitive layer sandwiched in between. This structure has poor compressibility and struggles to maintain high sensitivity over a wide linear pressure range, thus significantly limiting the application range of flexible pressure sensors.

[0003] The optimization concept of flexible pressure sensors is mainly based on structural optimization and the embedding of sensitive materials. For example, various microstructure arrays (such as bump arrays and micropillar arrays) are fabricated in the sensitive layer, and various nano / micro / nano composite materials are embedded to increase the contact area of ​​the sensing region, thereby increasing the change in electrical signal with pressure, thus improving the device's sensitivity and expanding the sensor's detection range. However, the fabrication of microstructure arrays is complex and costly; moreover, research has found that the bonding force between nano / micro / nano composite materials and the matrix material is poor, making them prone to detachment from the sensitive layer matrix during use, affecting sensor performance. Therefore, there is an urgent need to explore a new paradigm for sensor design and fabrication strategies to achieve flexible pressure sensors that are simple in structure, easy to fabricate, low in cost, stable in performance, and possess both wide measurement range and high sensitivity. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a flexible pressure sensor based on surface energy gradient multilayer fiber membrane and its fabrication method. This method proposes a novel flexible pressure sensor with surface energy gradient and multilayer stacked structure and its fabrication method, which has the advantages of simple structure, convenient fabrication, stable performance, wide measurement range, and high sensitivity.

[0005] The objective of this invention can be achieved through the following technical solutions:

[0006] A flexible pressure sensor based on surface energy gradient multilayer fiber membrane has the following structure from top to bottom: top flexible substrate, top electrode layer, first sensitive layer, second sensitive layer, third sensitive layer, bottom electrode layer, and bottom flexible substrate.

[0007] Both the top and bottom flexible substrates are made of polymer films; the top and bottom electrode layers are patterned conductive metal films; the first, second, and third sensitive layers are carried by fiber fabrics and embedded with different amounts of silver nanowires and Mxene.

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

[0009] The first sensitive layer, the second sensitive layer, and the third sensitive layer are stacked sequentially 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 placed between the top flexible substrate and the bottom flexible substrate.

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

[0012] Step 1: Place the fibrous fabric in an ultrasonic cleaner and clean it with anhydrous ethanol and deionized water respectively. After cleaning, place it in an oven to dry.

[0013] Step 2: The fiber fabric from Step 1 is surface-treated using dielectric barrier discharge (DBD) technology;

[0014] Step 3: Immerse the fiber fabric from Step 2 in a solution of silver nanowires, and then dry it in an oven to obtain a fiber fabric embedded with silver nanowires.

[0015] Step 4: Immerse the fiber fabric embedded with silver nanowires from Step 3 in Mxene dispersion, and then dry it in an oven to obtain fiber fabric embedded with silver nanowires and Mxene.

[0016] Step 5: Cut the fiber fabric embedded with silver nanowires and Mxene obtained in Step 4 into the same size as the top flexible substrate and the bottom flexible substrate, and use it as the sensitive layer; repeat Step 1 to Step 4 to obtain fiber fabrics embedded with different contents of silver nanowires and Mxene, which are used as the first sensitive layer, the second sensitive layer and the third sensitive layer respectively.

[0017] Step 6: Stack the first, second, and third sensitive layers obtained in Step 5 into a multilayer structure in order of increasing DBD processing time, and place them between the top and bottom electrode layers. Finally, encapsulate them using a top flexible substrate and a bottom flexible substrate to fabricate a multilayer fiber membrane flexible pressure sensor based on surface energy gradient.

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

[0019] Preferably, the oven temperature in steps one, three, and four is set to 60°C, and the drying time is 30 minutes; the soaking time in steps three and four is 12 hours.

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

[0021] The beneficial effects of this invention are:

[0022] 1. This invention designs a flexible pressure sensor based on a multilayer stacked fiber membrane with surface energy gradient. By utilizing the different surface energies of the fiber membrane, different amounts of micro / nano-sensitive materials can be adsorbed, and a sensitive layer can be formed through simple stacking. Therefore, it has advantages such as novel structure and simple composition.

[0023] 2. This invention uses 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. This not only increases the contact area of ​​the sensing region of the device, but also increases the bonding force between the micro / nano sensitive materials and the fiber membrane, effectively improving the performance of the flexible pressure sensor. Attached Figure Description

[0024] The invention will now be further described with reference to the accompanying drawings.

[0025] Figure 1 This is a schematic diagram of a flexible pressure sensor structure based on a multilayer stacked fiber membrane with surface energy gradient according to the present invention.

[0026] Figure 2 This is a process flow diagram of the fabrication process of a flexible pressure sensor based on a surface energy gradient multilayer stacked fiber membrane according to the present invention.

[0027] Figure 3 The images are scanning electron microscope (SEM) images of the sensitive layers after (a) no treatment and (b) 1 minute, (c) 3 minutes, and (d) 5 minutes of DBD treatment, respectively, in an example of the present invention.

[0028] Figure 4 This invention relates to the sensitivity of flexible pressure sensors with and without surface energy gradients in one embodiment.

[0029] In the picture:

[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 Implementation

[0031] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0032] like Figure 1 , Figure 2 As shown, a flexible pressure sensor based on a multilayer stacked fiber membrane with surface energy gradient is described. The structure of the flexible pressure sensor from top to bottom consists of 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 polymer films; 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 carried by fiber fabric and embedded with different amounts of silver nanowires 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 sequentially 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 fabricating a flexible pressure sensor based on a surface energy gradient multilayer fiber membrane is provided, comprising the following steps:

[0038] Step 1: Place the fibrous fabric in an ultrasonic cleaner and clean it with anhydrous ethanol and deionized water respectively. After cleaning, place it in an oven to dry.

[0039] Step 2: The fiber fabric from Step 1 is surface-treated using dielectric barrier discharge (DBD) technology;

[0040] Step 3: Immerse the fiber fabric from Step 2 in a solution of silver nanowires, and then dry it in an oven to obtain a fiber fabric embedded with silver nanowires.

[0041] Step 4: Soak the fiber fabric embedded with silver nanowires from Step 3 in Mxene, and then dry it in an oven to obtain the fiber fabric embedded with silver nanowires and Mxene.

[0042] Step 5: Cut the fiber fabric embedded with silver nanowires and Mxene obtained in Step 4 into the same size as the top flexible substrate U1 and the bottom flexible substrate B1, and use it as the sensitive layer; repeat Step 1 to Step 4 to obtain fiber fabrics embedded with different contents of silver nanowires and Mxene, which are respectively used as the first sensitive layer S1, the second sensitive layer S2 and the third sensitive layer S3.

[0043] Step 6: Stack the first sensitive layer S1, the second sensitive layer S2, and the third sensitive layer S3 obtained in Step 5 into a multilayer structure in order of increasing DBD processing time, and place them between the top electrode layer U2 and the bottom electrode layer B2. Finally, encapsulate them with the top flexible substrate U1 and the bottom flexible substrate U2 to make a multilayer fiber membrane flexible pressure sensor based on surface energy gradient.

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

[0045] In a preferred embodiment, the oven temperature is set to 60°C and the drying time is 30 minutes in steps one, three, and four; the soaking time is 12 hours in steps three and four.

[0046] In a preferred embodiment, after the fiber fabric undergoes DBD surface treatment on one surface in step two, it is flipped over for treatment of the other surface, ensuring that both surfaces of the fiber fabric are treated; and the total DBD surface treatment times for the first sensitive layer S1, the second sensitive layer S2, and the third sensitive layer S3 in steps two and five are 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 sequentially, and the amount of sensitive material attached to the surface of the fiber fabric also increases sequentially.

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

[0048] like Figure 4 Compared to flexible pressure sensors with no surface energy gradient, flexible pressure sensors with surface energy gradient prepared after DBD treatment have better sensitivity and detection range.

[0049] In other embodiments, flexible pressure sensors with different sensing performances can be fabricated by selecting different DBD processing times, the number of sensitive layers stacked, the type of sensitive material, etc.

[0050] The above detailed embodiments provide a specific description of the analytical methods involved in this invention. It should be noted that the above description is only intended to help those skilled in the art better understand the methods and ideas of this invention, and is not intended to limit the scope of the invention. Without departing from the principles of this invention, those skilled in the art can make appropriate adjustments or modifications to this invention, and such adjustments and modifications should also fall within the protection scope of this invention.

Claims

1. A method for preparing a multilayer fiber membrane flexible pressure sensor based on surface energy gradient, characterized in that, The method comprises the following steps: Step 1: Place the fiber fabric in an ultrasonic cleaner and clean it with anhydrous ethanol and deionized water respectively, and then take it out and place it in an oven for drying; Step 2: Surface treat the fiber fabric in step 1 by using dielectric barrier discharge technology; Step 3: Place the fiber fabric in step 2 in a nanosilver wire solution for soaking, and then place it in an oven for drying after soaking to obtain a fiber fabric embedded with nanosilver wires; Step 4: Place the fiber fabric embedded with nanosilver wires in step 3 in a Mxene dispersion solution for soaking, and then place it in an oven for drying after soaking to obtain a fiber fabric embedded with nanosilver wires and Mxene; Step 5: Cut the fiber fabric embedded with nanosilver 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 nanosilver wires and Mxene as a first sensitive layer, a second sensitive layer and a third sensitive layer respectively; Step 6: Stack the first sensitive layer, the second sensitive layer and the third sensitive layer obtained in step 5 into a multi-layer structure in the order of increasing DBD treatment time, and place them between the top electrode layer and the bottom electrode layer, and finally encapsulate them with the top flexible substrate and the bottom flexible substrate to make 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.

2. The method of claim 1, wherein the method further comprises: The top flexible substrate and the bottom flexible substrate are both polymer films; the top electrode layer and the bottom electrode layer are patterned conductive metal films; and the first sensitive layer, the second sensitive layer and the third sensitive layer are fiber fabrics as carriers and embedded with different contents of nanosilver wires and Mxene.

3. The method of claim 1, wherein the method further comprises: The top electrode layer is deposited on the surface of the top flexible substrate, and the bottom electrode layer is deposited on the surface of the bottom flexible substrate.

4. The method of claim 1, wherein the method further comprises: The top electrode layer and the bottom electrode layer are stacked face to face and placed between the top flexible substrate and the bottom flexible substrate.

5. The method of claim 1, wherein the method further comprises: The fiber fabric in step 1 is a polyester fiber fabric or a cotton fabric, and the thickness is 1 mm.

6. The method of claim 1, wherein the method further comprises: The temperature of the oven in steps 1, 3 and 4 is set to 60℃, and the drying time is 30 minutes; the soaking time in steps 3 and 4 is 12 hours.

7. The method of claim 1, wherein the method further comprises: In step 2, the fiber fabric is treated on one surface by DBD surface treatment, and then turned over to treat the other surface, so that both surfaces 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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