An asymmetric diaphragm pressure sensor

Abstract

The application discloses an asymmetric thin film pressure sensor and relates to the technical field of sensors.The asymmetric thin film pressure sensor comprises a spacing layer provided with a through hole, a polyvinylidene fluoride piezoelectric film, a lower electrode sheet, an upper electrode sheet arranged on a wave-encountering surface of the polyvinylidene fluoride piezoelectric film, an outer insulating layer and a wiring terminal point; a prismatic ring-shaped gap is formed between a side of the polyvinylidene fluoride piezoelectric film which is higher than the spacing layer, a wave-encountering inclined surface of the upper electrode sheet and an upper surface of the spacing layer; and the spacing layer, the polyvinylidene fluoride piezoelectric film, the lower electrode sheet, the upper electrode sheet and the outer insulating layer are stacked to form an asymmetric structure.In the application, the other side of the polyvinylidene fluoride piezoelectric film is tightly combined with a lower PI copper-clad film through pre-pressing, the polyvinylidene fluoride piezoelectric film is designed to be convex, the asymmetric thin film pressure sensor can obtain a signal capture rate under a larger incident angle loading condition, the influence of the movement of a packaging layer is reduced, and the surface wrinkle influence of a larger wave-encountering surface packaging on the measurement error is reduced.

Description

Technical Field

[0001] This invention belongs to the field of sensor technology, and in particular relates to an asymmetric thin-film pressure sensor. Background Technology

[0002] A pressure sensor is a device or apparatus that can sense pressure signals and convert them into usable output electrical signals according to certain rules. Thin-film pressure sensors are pressure sensors with a thin profile. According to the technical specifications of thin-film pressure sensors, polyvinylidene fluoride piezoelectric films are also known as PVDF. When used as pressure sensors, these films have the following advantages: (1) large piezoelectric constant; (2) high frequency response and large measurement range; (3) low acoustic impedance. Compared with other sensitive elements such as tourmaline, piezoelectric quartz, piezoelectric ceramics, and manganese copper that can be used for shock wave pressure measurement, polyvinylidene fluoride piezoelectric films are more suitable for the effective measurement of shock wave pressure.

[0003] Existing PVDF pressure sensors are widely used in the field of shock wave measurement, and most of them adopt copper-clad laminate PVDF structure. They have the following problems: (1) Since the copper electrode and the piezoelectric film are in free contact, and the external insulating layer and copper encapsulation layer of the sensor have high rigidity, the pressure amplitude of the shock wave is small. When such sensors receive pressure, they need to press the front and rear electrodes and the piezoelectric film together before they can generate a stable output signal. When the sensor measures a large pressure or is located inside a solid structure that can be pre-stressed, the influence of this free contact is small; however, when the measured pressure is small, the rigidity and displacement of the encapsulation layer will lead to a large deviation in the measurement result; (2) The copper electrode attached to the thick insulating film is copper-clad on the whole surface, with a large thickness and rigidity. Considering the uncertainty of the loading direction of the actual shock wave, the surface wrinkles of the rigid wave-facing encapsulation layer are prone to causing measurement errors. Therefore, in order to improve the signal capture rate of the structure surface under different incident angle loading conditions of the shock wave and reduce the influence of the encapsulation layer movement, it is of great significance to provide the asymmetric thin film pressure sensor of this technical solution. Summary of the Invention

[0004] This invention provides an asymmetric thin-film pressure sensor that solves the above problems.

[0005] To solve the above-mentioned technical problems, the present invention is achieved through the following technical solution:

[0006] An asymmetric thin-film pressure sensor of the present invention includes a spacer layer disposed in the middle and having a through hole in the middle, a polyvinylidene fluoride piezoelectric film disposed in the through hole and matched therewith, a lower electrode plate disposed on the bottom surface of the polyvinylidene fluoride piezoelectric film, an upper electrode plate disposed on the upper wave-facing surface of the polyvinylidene fluoride piezoelectric film, an outer insulating layer disposed on the outer surface of the lower electrode plate and the upper electrode plate, and a wiring terminal installed on the upper electrode plate and the lower electrode plate.

[0007] The bottom surface of the polyvinylidene fluoride piezoelectric film is flush with the surface of the lower electrode sheet; after the bottom of the upper electrode sheet is attached to the surface of the polyvinylidene fluoride piezoelectric film, wave-facing slopes are formed on both sides and extend to be attached to the upper surface of the spacer layer; the lower surface of the spacer layer is attached to the outer insulating layer; the side of the polyvinylidene fluoride piezoelectric film that is higher than the spacer layer forms a frustum-shaped annular gap with the wave-facing slope of the upper electrode sheet and the upper surface of the spacer layer; the polyvinylidene fluoride piezoelectric film is located at the center of the gap.

[0008] The spacer layer, polyvinylidene fluoride piezoelectric film, lower electrode sheet, upper electrode sheet, and outer insulating layer are stacked to form an asymmetric structure.

[0009] Furthermore, the upper electrode sheet adopts a flexible and adhesive fiber-woven substrate layer with conductive adhesive on both sides. Specifically, the fiber-woven substrate layer adopts an aluminized film woven fabric with a thickness of 0.0125mm-0.2mm.

[0010] Furthermore, the polyvinylidene fluoride piezoelectric film is circular with a diameter of 5±0.1mm and a thickness of 0.053mm-0.06mm.

[0011] Furthermore, the upper electrode uses a double-sided PI copper-clad film with a thickness of 0.02mm-0.2mm.

[0012] Furthermore, the spacer layer is made of PET film with a thickness of 0.012mm-0.05mm.

[0013] Furthermore, the outer insulating layer is a PI film with a thickness of 0.002mm-0.25mm.

[0014] Furthermore, the connection endpoint is a solder joint.

[0015] The present invention has the following advantages over the prior art:

[0016] The thin-film pressure sensor of this invention uses an asymmetric arrangement, including a lower electrode sheet made of PI copper-clad film, a flexible and adhesive upper electrode sheet made of aluminized film woven fabric, a spacer layer with a through hole in the middle to accommodate a polyvinylidene fluoride piezoelectric film, and an outer insulating layer on the outer surfaces of the upper and lower electrode sheets. The PI copper-clad film serves as a contact electrode on one side, which is the sensor's shield. It is directly mounted to the structural surface using conductive adhesive. The upper electrode sheet, made of aluminized film woven fabric, is used for the wave-facing side of the sensor. It has conductivity and double-sided adhesive properties. The wave-facing side of the polyvinylidene fluoride piezoelectric film is directly bonded and fixed to the upper electrode. The other side of the polyvinylidene fluoride piezoelectric film is tightly bonded to the lower PI copper-clad film through pre-compression. With the polyvinylidene fluoride piezoelectric film protruding design, the asymmetric thin-film pressure sensor can obtain a signal capture rate under a larger incident angle loading condition, reduce the influence of encapsulation layer movement, and reduce the surface wrinkles caused by the large wave-facing encapsulation, thus reducing measurement errors.

[0017] Of course, any product implementing this invention does not necessarily need to achieve all of the advantages described above at the same time. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is an exploded view of the structure of a specific embodiment of the present invention;

[0020] Figure 2 for Figure 1 A side view of the structure of the asymmetric thin-film pressure sensor corresponding to a specific embodiment;

[0021] Figure 3 The graph shows the relative current of an asymmetric thin-film pressure sensor according to a specific embodiment of the present invention as a function of pressure at 5V.

[0022] Figure 4 This is a graph showing the signal response time and recovery time of an asymmetric thin-film pressure sensor according to a specific embodiment of the present invention at a pressure of 2 MPa.

[0023] The attached diagram lists the components represented by each number as follows:

[0024] 1-Lower electrode plate, 2-Upper electrode plate, 3-Outer insulating layer, 4-Polyvinylidene fluoride piezoelectric film, 5-Spacer layer, 501-Through hole, 502-Gap, 6-Connecting terminal. Detailed Implementation

[0025] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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 skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] In the description of this invention, it should be understood that the terms "inner", "bottom surface", "outer surface", "both sides", "center position", etc., which indicate orientation or positional relationship, are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the components or elements referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as limiting this invention.

[0027] Please see Figure 1-2 As shown, an asymmetric thin-film pressure sensor of the present invention includes a spacer layer 5 disposed in the middle and having a through hole 501 in the middle, a polyvinylidene fluoride piezoelectric film 4 disposed in the through hole 501 and matched thereto, a lower electrode plate 1 disposed on the bottom surface of the polyvinylidene fluoride piezoelectric film 4, an upper electrode plate 2 disposed on the upper wave-facing surface of the polyvinylidene fluoride piezoelectric film 4, an outer insulating layer 3 disposed on the outer surface of the lower electrode plate 1 and the upper electrode plate 2, and a wiring terminal 6 mounted on the upper electrode plate 2 and the lower electrode plate 1; the wiring terminal 6 is a solder joint.

[0028] like Figure 1-2 As shown, in this specific embodiment, the upper electrode 2 adopts a flexible and adhesive fiber-woven substrate layer with conductive adhesive on both sides. Specifically, the fiber-woven substrate layer is made of aluminized film woven fabric with a thickness of 0.0125mm-0.2mm, specifically 0.08mm in this embodiment. The polyvinylidene fluoride piezoelectric film 4 is circular with a diameter of 5mm and a thickness of 0.053mm. The polyvinylidene fluoride piezoelectric film 4 is a PVDF piezoelectric film, and the polyvinylidene fluoride piezoelectric film 4 is made of 5mm diameter material imported from Measurement Company. A 3μm thick, electrodeless transparent piezoelectric film was used. However, considering the uniformity of the thickness of the entire PVDF (27cm×50cm) piezoelectric film, actual measurements showed that the thickness of a circular piezoelectric film element with a diameter of 5mm varied from 45-55μm. The spacer layer 5 was made of PET film with a thickness of 0.025mm. The outer insulating layer 3 was made of PI film with a thickness of 0.028mm. The spacer layer 5, the polyvinylidene fluoride piezoelectric film 4, the lower electrode sheet 1, the upper electrode sheet 2, and the outer insulating layer 3 were stacked to form an asymmetrical structure.

[0029] In this specific embodiment, the bottom surface of the polyvinylidene fluoride piezoelectric film 4 is flush with the surface of the lower electrode sheet 1; after the bottom of the upper electrode sheet 2 is attached to the surface of the polyvinylidene fluoride piezoelectric film 4, wave-facing slopes are formed on both sides and extend to be attached to the upper surface of the spacer layer 5. The lower surface of the spacer layer 5 is attached to the outer insulating layer 3. The side of the polyvinylidene fluoride piezoelectric film 4 that is higher than the spacer layer 5 forms a frustum-shaped annular gap 502 with the wave-facing slope of the upper electrode sheet 2 and the upper surface of the spacer layer 5. The polyvinylidene fluoride piezoelectric film 4 is located at the center of the gap 502.

[0030] like Figure 3 To transform the curve of relative current versus pressure of the asymmetric thin-film pressure sensor in the above specific embodiment at 5V voltage, from... Figure 3 It can be seen that the sensor has high sensitivity under low pressure and a wide sensitivity range of 30Pa-2MPa under high pressure. Furthermore, the current changes monotonically over time, exhibiting good linearity under both high and low pressure conditions.

[0031] like Figure 4 As shown, the signal response time and recovery time of the asymmetric thin-film pressure sensor in the above specific embodiment at a pressure of 2MPa are transformed by... Figure 4 It can be seen that the signal response time and recovery time of the two specific embodiments of this technical solution are relatively short when subjected to a pressure of 2MPa.

[0032] The thin-film pressure sensor of this invention uses an asymmetric arrangement, including a lower electrode sheet made of PI copper-clad film, a flexible and adhesive upper electrode sheet made of aluminized film woven fabric, a spacer layer with a through hole in the middle to accommodate a polyvinylidene fluoride piezoelectric film, and an outer insulating layer on the outer surfaces of the upper and lower electrode sheets. The PI copper-clad film serves as a contact electrode on one side, which is the sensor's shield. It is directly mounted to the structural surface using conductive adhesive. The upper electrode sheet, made of aluminized film woven fabric, is used for the wave-facing side of the sensor. It has conductivity and double-sided adhesive properties. The wave-facing side of the polyvinylidene fluoride piezoelectric film is directly bonded and fixed to the upper electrode. The other side of the polyvinylidene fluoride piezoelectric film is tightly bonded to the lower PI copper-clad film through pre-compression. With the polyvinylidene fluoride piezoelectric film protruding design, the asymmetric thin-film pressure sensor can obtain a signal capture rate under a larger incident angle loading condition, reduce the influence of encapsulation layer movement, and reduce the surface wrinkles caused by the large wave-facing encapsulation, thus reducing measurement errors.

[0033] The thin-film pressure sensor of this invention employs a symmetrically arranged sandwich structure consisting of an insulating film with a central hole in the middle layer, on which a polyvinylidene fluoride (PVDF) piezoelectric membrane is placed. Insulating films and outer insulating layers are arranged on both sides of the PVDF piezoelectric membrane. This design eliminates direct pressing and adhesive bonding between the PVDF piezoelectric membrane and the insulating film, ensuring free deformation of the piezoelectric membrane under out-of-plane pressure loads. Furthermore, considering the potential for significant in-plane lateral deformation of the piezoelectric membrane under high pressure, a certain gap is provided between the central hole and the piezoelectric membrane. This design offers advantages such as high pressure detection sensitivity, a wide sensitivity range, and a short response time.

[0034] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. An asymmetric thin-film pressure sensor, characterized in that: It includes a spacer layer (5) with a through hole (501) in the middle, a polyvinylidene fluoride piezoelectric film (4) in the through hole (501) and matching thereto, a lower electrode plate (1) on the bottom surface of the polyvinylidene fluoride piezoelectric film (4), an upper electrode plate (2) on the upper wave-facing surface of the polyvinylidene fluoride piezoelectric film (4), an outer insulating layer (3) on the outer surface of the lower electrode plate (1) and the upper electrode plate (2), and wiring terminals (6) installed on the upper electrode plate (2) and the lower electrode plate (1); The bottom surface of the polyvinylidene fluoride piezoelectric film (4) is flush with the surface of the lower electrode sheet (1); after the bottom of the upper electrode sheet (2) is attached to the surface of the polyvinylidene fluoride piezoelectric film (4), wave-facing slopes are formed on both sides and extended to be attached to the upper surface of the spacer layer (5); the lower surface of the spacer layer (5) is attached to the outer insulating layer (3); the side of the polyvinylidene fluoride piezoelectric film (4) that is higher than the spacer layer (5) forms a frustum-shaped annular gap (502) with the wave-facing slope of the upper electrode sheet (2) and the upper surface of the spacer layer (5); the polyvinylidene fluoride piezoelectric film (4) is located at the center of the gap (502). The spacer layer (5), polyvinylidene fluoride piezoelectric film (4), lower electrode sheet (1), upper electrode sheet (2), and outer insulating layer (3) are stacked to form an asymmetric structure.

2. The asymmetric thin-film pressure sensor according to claim 1, characterized in that, The upper electrode sheet (2) is made of a flexible and adhesive fiber woven substrate layer with conductive adhesive on both sides. Specifically, the fiber woven substrate layer is made of aluminum-coated film woven fabric with a thickness of 0.0125mm-0.2mm.

3. The asymmetric thin-film pressure sensor according to claim 1, characterized in that, The polyvinylidene fluoride piezoelectric film (4) is circular with a diameter of 5±0.1mm and a thickness of 0.053mm-0.06mm.

4. An asymmetric thin-film pressure sensor according to claim 1, characterized in that, The upper electrode sheet (2) is made of double-sided PI copper-clad film with a thickness of 0.02mm-0.2mm.

5. An asymmetric thin-film pressure sensor according to claim 1, characterized in that, The spacer layer (5) is made of PET film with a thickness of 0.012mm-0.05mm.

6. An asymmetric thin-film pressure sensor according to claim 1, characterized in that, The outer insulation layer (3) is made of PI film with a thickness of 0.002mm-0.25mm.

7. An asymmetric thin-film pressure sensor according to claim 1, characterized in that, The connection point (6) is a solder joint.

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