Flexible sensor prepared from self-powered piezoelectric nanofiber membrane

Abstract

The invention belongs to the field of flexible sensors, and particularly relates to a flexible sensor prepared from a self-powered piezoelectric nanofiber membrane, and in addition, the prepared sensor also has a human physiological signal acquisition function. The sensor is composed of silicone rubber (Ecoflex 00-30), a polyvinylidene fluoride (PVDF) nanofiber membrane and a copper electrode. As the polyvinylidene fluoride nanofiber membrane prepared by the electrostatic spinning technology is nanoscale, certain surface roughness can be increased when the polyvinylidene fluoride nanofiber membrane is attached to the surface of the silicone rubber, the output performance of the sensor is improved, and meanwhile, due to the hydrophobic property of the polyvinylidene fluoride nanofiber membrane, the sensor can be used for detecting the surface roughness of the silicon rubber. When external energy is collected, the friction loss between a solid friction surface and external liquid is greatly reduced, so that the service life of the sensor is prolonged; finally, by testing the sensor, it is found that the sensor has huge potential in the application field of external energy collection and human physiological signal collection.

Description

Technical Field

[0001] The invention belongs to the field of flexible sensors, and in particular relates to a flexible sensor prepared by a self-powered piezoelectric nanofiber membrane. Background Art

[0002] Faced with the energy crisis dilemma of the development and utilization of traditional fossil energy such as greenhouse effect, water and air pollution, people are increasingly aware of the importance of developing renewable clean energy as an alternative to wind, solar and tidal energy. However, despite the abundant reserves of renewable energy, there are still obstacles to development and transformation, such as high equipment cost, limited geographical location and low conversion efficiency. In addition, in the past decade, with the widespread application of smart flexible wearable devices in medical monitoring, human-computer interaction and artificial intelligence, although the power consumption of these electronic devices and systems has made great progress in reducing, energy supply and consumption remain the most critical constraints in the development of flexible electronics. Therefore, it is highly desirable to develop a new series of flexible self-powered smart electronic products, which are not only self-powered sensors, but also can provide power for micro-nano electronic devices with low power consumption, thus avoiding the use of harmful chemical batteries. In this context, sensors based on triboelectric nanogenerators (TENGs) have become a promising alternative to flexible sensors due to their inherent characteristics such as self-powering, high sensitivity, light weight, easy manufacturing, cost-effectiveness and non-invasiveness. Triboelectric nanogenerators can effectively convert biomechanical energy from human movement into electrical energy through contact electrification and electrostatic induction phenomena.

[0003] The fiber membrane prepared by electrospinning technology has the advantages of ultra-fine fibers, small pore size, and high specific surface area, thereby increasing the surface roughness and specific surface area, thereby increasing the output performance of the sensor. In addition, the polyvinylidene fluoride nanofiber membrane prepared by electrospinning technology, because of its hydrophobic nature, can greatly reduce the loss caused by repeated friction between silicone rubber and external liquid, and prolong the flexible sensor.

[0004] Therefore, the use of hydrophobic electrospun nanofiber membranes has important application prospects for friction layers that collect external energy.

[0005] Therefore, the present invention adopts electrostatic spinning technology to prepare a self-powered microfluidic flexible sensor with long service life, low detection limit and good output performance. The sensor is composed of silicone rubber (Ecoflex 00-30), polyvinylidene fluoride (PVDF) nanofiber membrane and copper electrode. Since the polyvinylidene fluoride nanofiber membrane prepared by electrostatic spinning technology is nanoscale, it will increase a certain surface roughness when attached to the silicone rubber surface, thus improving the output performance of the flexible sensor. At the same time, due to its hydrophobic nature, the friction loss between the solid friction surface and the external liquid is greatly reduced, which is not only convenient for collecting the energy brought by the external liquid, but also greatly prolongs the life of the flexible sensor; finally, through the test of the flexible sensor, it is found that it has great potential in the application field of human physiological signal acquisition. Summary of the invention

[0006] The purpose of the present invention is to prepare a sensor made of a self-powered piezoelectric nanofiber membrane. In addition, the prepared sensor can realize the functions of collecting external energy and collecting human physiological signals. In order to achieve the above purpose, the present invention adopts the following technical solutions:

[0007] A sensor made of self-powered piezoelectric nanofiber membrane, composed of silicone rubber (Ecoflex 00-30), polyvinylidene fluoride (PVDF) nanofiber membrane and copper electrode:

[0008] Further, the materials used are silicone rubber (Ecoflex 00-30), polyvinylidene fluoride and copper foil.

[0009] Further, the preparation method includes the following steps: firstly dissolving polyvinylidene fluoride in a mixed solvent of acetone and N,N-dimethylformamide (7:3), then loading into a syringe, and adjusting the voltage and flow rate of an electrospinning machine to prepare a fiber membrane;

[0010] Furthermore, the preparation method of the fiber membrane is as follows: the concentration of polyvinylidene fluoride is 18% to 20% (w / v); the spinning voltage is 15kV to 18kV; the flow rate is 1mL / h to 1.5mL / h, and the spinning time of the fiber membrane is 15 to 20min.

[0011] Furthermore, the fiber membrane is adhered to semi-cured silicone rubber (Ecoflex), copper foil is adhered to the silicone rubber on the other side as an electrode, and a wire is led out for connection with the outside world.

[0012] The above technical solutions have the following benefits:

[0013] (1) Due to its hydrophobic nature, the PVDF nanofiber membrane can significantly reduce the friction loss between the external liquid and the silicone rubber surface, thereby extending the life of the flexible sensor.

[0014] (2) PVDF also has better flexibility and long-term stability, which can increase the output performance of the flexible sensor.

[0015] (3) Since Ecoflex is selected as the flexible silicone rubber substrate, it can be attached to the human body to the greatest extent, making the flexible sensor test more stable. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings / schedules required for use in the embodiments or the description of the prior art.

[0017] Figure 1 Schematic diagram of the appearance of the flexible sensor;

[0018] Figure 2 This is a scanning electron microscope image of PVDF nanofiber membrane;

[0019] Figure 3 The water contact angle changes before and after the introduction of PVDF nanofiber membrane, (a) is the water contact angle of silicone rubber (Ecoflex 00-30), (b) is the water contact angle of PVDF nanofiber membrane;

[0020] Figure 4 Diagram of flexible sensors used for physiological signal acquisition.

[0021] Figure 5 This is a signal diagram of the flexible sensor collecting continuous dripping of water droplets. DETAILED DESCRIPTION

[0022] The technical solutions in the embodiments of the present invention are described in detail below. 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.

[0023] Example 1: Preparation of PVDF nanofiber membrane

[0024] 5.4 g of polyvinylidene fluoride was dissolved in 3 ml of a mixed solvent of acetone and N,N-dimethylformamide (7:3), and rotated on a magnetic stirrer at 50°C for 4 h. The spinning solution was then loaded into a syringe, the voltage was adjusted to 15 kV, the flow rate was 1 mL / h, and the spinning was carried out for 20 min.

[0025] Example 2: Preparation of flexible sensor based on triboelectric nanogenerator

[0026] The prepolymer and curing agent of silicone rubber Ecoflex 00-30 were mixed in a volume ratio of 1:1 and distributed on a flat glass. The thickness of the sample was controlled by spin coating (300 rpm, 45 s), heated to 60°C, and in its semi-cured state, the PVDF fiber membrane was attached to the bottom layer and heated to 60°C on a heating plate for 5 minutes. Finally, the copper foil was tightly attached to the other side of the silicone rubber and used as an electrode.

Claims

1. A flexible sensor made of self-powered piezoelectric nanofiber membrane, characterized in that: It is composed of silicone rubber (Ecoflex00-30), polyvinylidene fluoride (PVDF) nanofiber membrane and copper electrodes.

2. The flexible sensor made of self-powered piezoelectric nanofiber membrane according to claim 1, characterized in that: The materials used were silicone rubber (Ecoflex 00-30), polyvinylidene fluoride and copper foil.

3. The flexible sensor made of self-powered piezoelectric nanofiber membrane according to claim 1, characterized in that: The preparation method comprises the following steps: firstly dissolving polyvinylidene fluoride in a mixed solvent of acetone and N,N-dimethylformamide (7:3), then loading it into a syringe, and adjusting the voltage and flow rate of an electrostatic spinning machine to prepare a fiber membrane.

4. The flexible sensor made of self-powered piezoelectric nanofiber membrane according to claim 3, characterized in that: The preparation method of the fiber membrane is as follows: the concentration of polyvinylidene fluoride is 18% to 20% (w / v); the spinning voltage is 15kV to 18kV; the flow rate is 1mL / h to 1.5mL / h, and the spinning time of the fiber membrane is 15 to 20min.

5. The flexible sensor made of self-powered piezoelectric nanofiber membrane according to any one of claims 1 to 4, characterized in that: The fiber membrane is adhered to semi-cured silicone rubber (Ecoflex), copper foil is adhered to the silicone rubber on the other side as an electrode, and a wire is led out for connection with the outside world.

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