Micro air pressure sensor with enhanced sensitivity and preparation method thereof

Abstract

The invention discloses a sensitivity-enhanced micro air pressure sensor and a preparation method thereof, the sensitivity-enhanced micro air pressure sensor comprises a shell, a pressure sensing film, an insulating substrate and an electrode group, the shell is provided with a cavity and an air inlet, the pressure sensing film is arranged in the cavity to divide the cavity into a first cavity and a second cavity which are not communicated with each other, the first cavity is communicated with the air inlet, and the second cavity is a vacuum cavity; the insulating substrate is arranged in the second cavity, and a gap is formed between the insulating substrate and the pressure sensing film; the electrode group is installed on the side, opposite to the pressure sensing film, of the insulating substrate so as to output capacitance change signals generated by deformation of the pressure sensing film, the side, opposite to the pressure sensing film, of the electrode group is provided with a second microstructure, and the side, opposite to the second microstructure, of the pressure sensing film is provided with a first microstructure. The pressure sensing film deforms under the action of the pressure difference between the first cavity and the vacuum cavity, and when the pressure sensing film deforms until the second microstructure and the first microstructure are in contact and fit, an interlocking microstructure can be formed to achieve overload protection. The capacitance variation can be increased, and the precision and the sensitivity are improved.

Description

Technical Field

[0001] The present invention relates to the field of micro pressure sensors, and in particular to a micro pressure sensor with enhanced sensitivity and a preparation method thereof. Background Art

[0002] As a key component of the modern aerospace field, spacecraft not only integrates multiple functions such as spacecraft, space shuttles and transportation vehicles, but also plays an irreplaceable role in space exploration, military strategy, scientific research, environmental monitoring and technological innovation. When a spacecraft is flying close to space and low-Earth orbit, its surface will be affected by the tiny air pressure generated by the thin air at high altitudes. This continuous micro-air pressure may cause the tiny devices and equipment of the spacecraft to deform, loosen components, or even fall off, bringing serious consequences. Therefore, monitoring the tiny air pressure in the environment where the spacecraft is located is of great significance for both theoretical research and practical applications.

[0003] Micro pressure sensors are instruments used to measure the rarefaction of gases below atmospheric pressure. They indirectly measure air pressure through different physical phenomena. There are many types of modern micro pressure sensors with different working principles. Most of them use indirect pressure measurement methods. Among the existing micro pressure sensors, capacitance film vacuum gauges are widely used in various fields due to their high precision, fast response, wide measurement range, insensitivity to the type of measured gas, miniaturized design, low energy consumption operation and long-term stability. However, the current absolute pressure capacitance film vacuum gauges have problems such as small capacitance change, low vacuum degree, narrow pressure measurement range, and low accuracy in measuring tiny air pressure. There is currently huge room for improvement in detection accuracy. Summary of the invention

[0004] The main purpose of the present invention is to overcome the above-mentioned defects in the prior art and to propose a micro-pressure sensor with enhanced sensitivity and a preparation method thereof, which can increase the capacitance change, improve accuracy and sensitivity, and can measure tiny air pressures as low as a few Pascals, and is suitable for application scenarios of tiny air pressure detection.

[0005] The present invention adopts the following technical solution:

[0006] A micro pressure sensor with enhanced sensitivity comprises a shell, the shell is provided with a cavity and an air inlet, and also comprises a pressure-sensitive film, an insulating substrate and an electrode group; the pressure-sensitive film is arranged in the cavity to separate it into a first cavity and a second cavity which are not connected to each other, the first cavity is connected to the air inlet, and the second cavity is a vacuum cavity; the insulating substrate is arranged in the second cavity and has a gap between the pressure-sensitive film; the electrode group is installed on the side of the insulating substrate opposite to the pressure-sensitive film to output a capacitance change signal generated by the deformation of the pressure-sensitive film, and a second microstructure is arranged on the side of the electrode group opposite to the pressure-sensitive film, and a first microstructure is arranged on the side of the pressure-sensitive film opposite to the second microstructure, the pressure-sensitive film is deformed under the pressure difference between the first cavity and the vacuum cavity, and when the pressure-sensitive film is deformed to the point where the second microstructure contacts and fits with the first microstructure, an interlocking microstructure can be formed to achieve overload protection.

[0007] The electrode group includes an inner electrode and an outer electrode, the outer electrode is arranged around the inner electrode, the inner electrode and the outer electrode are respectively provided with lead-out electrodes passing through the second cavity to the outside of the shell, and the second microstructure is formed on the inner electrode.

[0008] A seat is fixed on the pressure-sensitive film at a position relative to the electrode group, and the first microstructure is formed on the seat; when the pressure-sensitive film is not deformed, the distance between the second microstructure and the first microstructure is 100-150 um.

[0009] The second microstructure includes a number of evenly distributed micropores, and the first microstructure includes a number of evenly distributed protrusions, or the second microstructure includes a number of evenly distributed protrusions, and the first microstructure includes a number of evenly distributed micropores; the protrusions are in the shape of a frustum, a prism or a pyramid; the micropores are concave holes adapted to the shape of the protrusions, and the height of the protrusions or the depth of the micropores is 50-200um.

[0010] The shell includes an upper shell and a lower shell which are relatively fixed to form the cavity, the inner wall of the lower shell is provided with a circumferentially distributed first convex ring, and the pressure-sensitive film is relatively fixed to the first convex ring; the inner wall of the upper shell is provided with a circumferentially distributed second convex ring, the insulating base is relatively fixed to the second convex ring, and the air inlet is formed on the lower shell and is provided with a filter.

[0011] At least one through hole is provided on a side of the second cavity away from the insulating substrate, the lead-out electrode of the electrode group is passed through the through hole, and a glass composition is filled between the through hole and the lead-out electrode.

[0012] At least one groove is arranged on a side of the second cavity away from the insulating substrate, a getter is placed in the groove, and a barrier net is arranged on a side of the groove communicating with the second cavity.

[0013] A method for preparing a micro pressure sensor with enhanced sensitivity comprises the following steps:

[0014] 1) Making a shell having a cavity and an air inlet;

[0015] 2) using laser to form the second microstructure and the first microstructure on the electrode group and the base respectively;

[0016] 3) welding the electrode group to the insulating substrate by vacuum brazing, and welding the insulating substrate to the cavity;

[0017] 4) The seat body having the first microstructure is vacuum brazed with the pressure-sensitive film, and the pressure-sensitive film is stretched and vacuum brazed in the cavity of the shell to separate the cavity into a first cavity and a second cavity that are not connected to each other. The second cavity is configured as a vacuum cavity, and the insulating substrate is located in the second cavity and is spaced apart from the pressure-sensitive film. The second microstructure is opposite to the first microstructure, and when the pressure-sensitive film is deformed to the point where the second microstructure is in contact with the first microstructure and fits in with each other, an interlocking microstructure can be formed to achieve overload protection.

[0018] Step 1) specifically includes preparing an upper shell and a lower shell respectively, and making a second convex ring, a groove and a through hole on the inner wall of the upper shell; making a first convex ring on the inner wall of the lower shell; in step 4), the pressure-sensitive film is welded and fixed to the first convex ring, and microholes are made on the getter by laser, the getter is placed in the groove and fixed by welding a barrier net, and in step 3), the insulating base is welded and fixed to the second convex ring, and after the lead-out electrode of the electrode group passes through the through hole, a glass composition is filled between the through hole and the lead-out electrode.

[0019] The electrode group includes an inner electrode and an outer electrode. In step 2), the second microstructure is manufactured on the surface of the inner electrode. In step 3), the inner electrode is welded to the insulating substrate, and the outer electrode is welded to the insulating substrate and surrounds the inner electrode.

[0020] It can be seen from the above description of the present invention that, compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. In the present invention, a pressure-sensitive film having a first microstructure and an insulating substrate having a second microstructure are provided, and a gap is controlled between the first microstructure and the second microstructure. When the air pressure entering the first cavity increases, the pressure-sensitive film is deformed under the action of the pressure difference between the first cavity and the vacuum cavity. When the pressure difference increases to a certain value, the first microstructure and the second microstructure are in contact and fit to realize an interlocking microstructure, thereby preventing further deformation of the pressure-sensitive film and thus playing an overload protection role.

[0022] 2. In the present invention, the first microstructure and the second microstructure use protrusions and micropores, and the protrusions and micropores can be selected in different shapes, such as pyramids, frustums or pyramids; when the pressure-sensitive film is not deformed, the interval between the first microstructure and the second microstructure is 100-150um; the height of the protrusion and the depth of the micropore are 50-200um. By using this interlocking microstructure, the detection sensitivity and accuracy of the micro pressure sensor are greatly improved while ensuring the overall miniaturization and integration of the sensor, and it can measure tiny air pressures as low as several Pascals.

[0023] 3. In the present invention, five-axis laser processing technology is used to process micropores with a high aspect ratio inside the getter, with a diameter of 200um and a height of 6mm. The microporous structure is used to increase the specific surface area of ​​the getter, thereby improving the air absorption performance of the getter. The vacuum degree of the sensor is improved to ensure that the working environment of the micro pressure sensor meets the requirements.

[0024] 4. In the present invention, the shell includes an upper shell and a lower shell. The inner walls of the upper shell and the lower shell are respectively provided with a first convex ring and a second convex ring to be welded and fixed to the insulating base and the pressure-sensitive film respectively. The fixing method is simple and reliable. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a cross-sectional view of the micro air pressure sensor of the present invention.

[0026] Figure 2 It is a structural diagram of the seat body of the present invention.

[0027] Figure 3 This is a diagram of the internal electrode structure of the present invention.

[0028] Figure 4 This is a schematic diagram of the interlocking structure.

[0029] Figure 5 This is a structural diagram of the getter of the present invention.

[0030] Figure 6 This is a displacement comparison diagram of the simulation models of the micro-air pressure sensor with an interlocking structure and the micro-air pressure sensor without a microstructure according to the present invention.

[0031] Figure 7This is a comparison chart of the simulated capacitance changes of the micro-air pressure sensor with an interlocking structure and the micro-air pressure sensor without a microstructure.

[0032] Figure 8 A comparison chart of the simulated relative capacitance changes of a micro pressure sensor with an interlocking structure and a micro pressure sensor without a micro structure.

[0033] Fig. 9 It is the main flow chart of the method of the present invention.

[0034] Fig.10 It is a shell composition diagram of the present invention.

[0035] Fig.11 A schematic diagram of the second microstructure, the first microstructure, the insulating substrate and the getter of the present invention.

[0036] Fig.12 It is a schematic diagram of fixing the getter of the present invention.

[0037] Fig.13 The figure is a schematic diagram showing that the electrode group is fixed to the insulating substrate and the insulating substrate is fixed to the upper shell.

[0038] Fig.14 This is a schematic diagram of the installation of related components on the lower case.

[0039] Fig.15 It is a schematic diagram of the installation of the pressure-sensitive film, the seat body and the lower shell.

[0040] Fig.16 This is a schematic diagram of the installation of the upper shell and the lower shell.

[0041] in:

[0042] 10. Shell; 11. Air inlet; 13. First cavity; 14. Second cavity; 15. Upper shell; 16. Lower shell; 15a. Second convex ring; 16a. First convex ring; 17. Tube; 18. Groove; 19. Through hole; 20. Pressure-sensitive film; 21. Base; 22. First microstructure; 30. Insulating substrate; 31. Micropore; 40. Electrode group; 41. Inner electrode; 42. Outer electrode; 43. Lead-out electrode; 44. Second microstructure; 50. Getter; 51. Barrier net; 60. Glass composition; 70. Filter net.

[0043] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. DETAILED DESCRIPTION

[0044] The present invention is further described below through specific implementation modes.

[0045] See also Figures 1 to 8A micro pressure sensor with enhanced sensitivity includes a housing 10, a pressure-sensitive film 20, an insulating substrate 30, an electrode group 40, etc. The housing 10 is provided with a cavity and an air inlet 11, and the air inlet 11 is connected to the cavity. The pressure-sensitive film 20 is arranged in the cavity to separate it into a first cavity 13 and a second cavity 14 that are not connected to each other, the first cavity 13 is connected to the air inlet 11, and the second cavity 14 is not connected to the air inlet 11 and is arranged as a vacuum cavity. The insulating substrate 30 is arranged in the second cavity 14 and a gap is formed between the insulating substrate 30 and the pressure-sensitive film 20. The electrode group 40 is installed on the side of the insulating base 30 opposite to the pressure-sensitive film 20 to output the capacitance change signal generated by the deformation of the pressure-sensitive film 20, and a second microstructure 44 is provided on the side of the electrode group 40 opposite to the pressure-sensitive film 20, and a first microstructure 22 is provided on the side of the pressure-sensitive film 20 opposite to the second microstructure 44. The pressure-sensitive film 20 can be deformed under the action of the pressure difference between the first cavity 13 and the vacuum cavity. When the pressure-sensitive film 20 is deformed to the point where the second microstructure 44 and the first microstructure 22 are in contact and fit, an interlocking microstructure can be formed to achieve overload protection.

[0046] Among them, the first cavity 13 is a detection cavity, and the gas to be tested enters the detection cavity through the air inlet 11. Under the action of the gas pressure in the detection cavity and the pressure difference between the vacuum cavity, the pressure-sensitive film 20 is deformed, and the capacitance between the insulating substrate 30 and the pressure-sensitive film 20 changes, so that the capacitance signal output by the electrode group 40 changes. The capacitance change signal is converted into a voltage or current signal output by an external conversion circuit, and the current air pressure value of the detection cavity can be obtained by signal processing.

[0047] The housing 10 includes an upper housing 15 and a lower housing 16 which are relatively fixed to form a cavity. The upper housing 15 and the lower housing 16 are sleeved at opposite ends and fixed by welding. The inner wall of the upper housing 15 is provided with a circumferentially distributed second convex ring 15a, and the inner wall of the lower housing 16 is provided with a circumferentially distributed first convex ring 16a. The insulating base 30 is relatively fixed to the second convex ring 15a, and the pressure-sensitive film 20 is relatively fixed to the first convex ring 16a; the air inlet 11 is formed on the lower housing 16.

[0048] The electrode group 40 includes an inner electrode 41 and an outer electrode 42, and the inner electrode 41 is circular, square or other polygonal. The outer electrode 42 is arranged around the inner electrode 41, for example, the outer electrode 42 is a circular ring, a square ring or a polygonal ring, etc., and there is a gap between the inner electrode 41 and the outer electrode 42. The inner electrode 41 and the outer electrode 42 are respectively provided with an extraction electrode 43 that passes through the second cavity 14 to the outside of the shell 10, that is, one end of the extraction electrode 43 is connected to the inner electrode 41 or the outer electrode 42, and the other end passes through the insulating substrate 30 and the side wall of the second cavity 14 to the outside of the shell 10. The second microstructure 44 is formed on the inner electrode 41. The insulating substrate 30 is provided with a micropore for the extraction electrode 43 to pass through, and the micropore is a micropore with a high-depth wall. The inner electrode 41 and the outer electrode 42 of the electrode group 40 are respectively fixed to the insulating substrate 30 by welding, and the inner electrode 41 is located in the middle of the insulating substrate 30, and the outer electrode 42 is close to the edge of the insulating substrate 30. The lead-out electrode 43 and the microhole, and the insulating base 30 and the second protruding ring 15a can be fixed by welding.

[0049] The seat 21 is fixed to the position of the relative electrode group 40 on the pressure-sensitive film 20, and the first microstructure 22 is formed on the seat 21. When the pressure-sensitive film 20 is not deformed, the distance between the second microstructure 44 and the first microstructure 22 is 100-150um. The seat 21 is located in the middle of the pressure-sensitive film 20, and the two can be fixed by welding. The pressure-sensitive film 20 is fixed to the first convex ring 16a by welding in a tensioned state.

[0050] The interlocking microstructure formed by the second microstructure 44 and the first microstructure 22 is a concave-convex matching structure. For example, the second microstructure 44 includes a number of evenly distributed micropores, and the first microstructure 22 includes a number of evenly distributed protrusions, or the second microstructure 44 includes a number of evenly distributed protrusions, and the first microstructure 22 includes a number of evenly distributed micropores. In practical applications, the shapes of the protrusions and micropores can be set according to requirements, for example, the protrusions are truncated cones, prisms, or pyramids, and the micropores are concave holes that match the shape of the protrusions, and the height of the protrusions or the depth of the micropores is 50-200um. Figure 4 In the figure, the protrusion is a prism, and its upper and lower surfaces are both square.

[0051] Furthermore, the air inlet 11 is connected to a tube body 17, which is welded to the air inlet 11 and the two are connected. A filter screen 70 is provided at the air inlet 11, and the filter screen 70 is used to filter impurities in the gas to be tested. The filter screen 70 is made of polytetrafluoroethylene material, and the filter screen 70 is fixed to the lower shell 16 by gluing.

[0052] At least one groove 18 is provided on the side of the second cavity 14 away from the insulating substrate 30, and a getter 50 is placed in the groove 18. The getter 50 is used to absorb the gas in the second cavity 14. A barrier net 51 is provided on the side of the groove 18 connected to the second cavity 14, and the barrier net 51 is fixed to the inner wall of the second cavity 14, so as to fix the getter 50 in the groove 18. The size of the groove 18 is adapted to the getter 50. The getter 50 adopts a non-evaporable Ti-based block getter, and its shape is adapted to the groove 18, for example, a column. The metal material of the barrier net 51 can be stainless steel, nickel, etc. In practical applications, five-axis laser processing of micropores 31 with a high aspect ratio can also be used on the getter 50 to improve the air absorption performance. For example, the micropores 31 processed on the getter 50 have a diameter of 200um and a height of 6mm, but are not limited to this.

[0053] At least one through hole 19 is provided on the side of the second cavity 14 away from the insulating substrate 30. The lead-out electrode 43 of the electrode group 40 is passed through the through hole 19. A glass composition 60 is filled between the through hole 19 and the lead-out electrode 43. The glass composition is used to ensure the vacuum degree of the second cavity 14 to prevent air leakage.

[0054] In the present invention, the upper shell 15, the lower shell 16, the pressure-sensitive film 20 and the base 21 are made of metal materials, such as nickel-chromium alloy. The insulating base 30 is made of ceramic materials, such as 95 aluminum oxide. The inner electrode 41 and the outer electrode 42 of the electrode group 40 can be made of metal materials such as copper, and the lead-out electrode 43 is made of copper.

[0055] When the micro-pressure sensor of the present invention is working, the pressure-sensitive film 20 with the first microstructure 22 is deformed under the pressure difference between the first cavity 13 and the vacuum cavity on both sides thereof, resulting in a capacitance change output through the lead-out electrode 43 of the electrode group 40. The capacitance change signal is converted into a voltage or current signal output by an external conversion circuit, and the current air pressure value of the detection cavity can be obtained by signal processing.

[0056] The COMSOL Multiphysics software is used to simulate the micro pressure sensor with interlocking microstructures and the micro pressure sensor without microstructures. First, a pressure-sensitive film 20 with a first microstructure 22, an inner electrode 41, an outer electrode 42, and 1 / 4 of the capacitance part of the vacuum cavity between the two are taken to build a model, such as Figure 6 The first microstructure 22 and the second microstructure 44 are of prism type, the upper and lower surfaces of the prism-shaped protrusions are both square, the lower surface side length is 200um, the upper surface side length is 50um, and the height is 100um; the shape of the micropores on the second microstructure 44 is adapted to the protrusions, and the depth is 100um.

[0057] For the case of 0-400Pa air pressure, the corresponding boundary conditions and parameters are set for the relevant structures, and the solution is directly obtained according to the coupling situation, such as Figure 7 , Figure 8 As shown, by comparing the capacitance change and relative capacitance change rate of the micro-pressure sensor with microstructure and the micro-pressure sensor without microstructure, it can be seen that the capacitance value, capacitance change and relative capacitance change rate of the micro-pressure sensor with interlocking microstructure are much greater than those of the sensor without microstructure.

[0058] See also Fig. 9 A method for preparing a micro-pressure sensor with enhanced sensitivity, which is used to prepare the above-mentioned micro-pressure sensor with enhanced sensitivity, comprises the following steps:

[0059] 1) A housing 10 having a cavity and an air inlet 11 is manufactured.

[0060] For details, see Fig.10 , prepare the upper shell 15 and the lower shell 16 respectively, and make the second convex ring 15a, the groove 18 and the through hole 19 on the inner wall of the upper shell 15, the second convex ring 15a is used to fix the insulating substrate 30, the groove 18 is used to place the getter 50, and the through hole 19 is used for the lead-out electrode 43 to pass through. Make the first convex ring 16a on the inner wall of the lower shell 16, and the first convex ring 16a is used to fix the pressure-sensitive film 20.

[0061] 2) Laser is used to manufacture the second microstructure 44 and the first microstructure 22 on the electrode group 40 and the base 21, respectively. The second microstructure 44 and the first microstructure 22 are realized by the combination of protrusions and microholes, and the shapes of the protrusions and microholes can be pyramids, prisms, pyramids, etc.

[0062] In this step, see Fig.11 , Fig.12 Since the electrode group 40 is provided with an inner electrode 41 and an outer electrode 42, a second microstructure 44 is made on the surface of the inner electrode 41 by a five-axis laser, and micropores are made on the getter 50 and the insulating substrate 30 by a laser, respectively, and the getter 50 is placed in the groove 18 of the upper shell 15 and fixed by welding the barrier mesh 51. The micropores on the insulating substrate 30 are used for the extraction electrode 43 to pass through.

[0063] 3) The electrode group 40 is welded to the insulating substrate 30 by vacuum welding, that is, the inner electrode 41 is welded to the insulating substrate 30, and the outer electrode 42 is welded to the insulating substrate 30 and surrounds the inner electrode 41. The insulating substrate 30 is welded to the upper shell 15, and the insulating substrate 30 and the second convex ring 15a are welded and fixed. After the lead electrodes 43 of the inner electrode 41 and the outer electrode 42 pass through the through hole 19, the glass composition 60 is filled between the through hole 19 and the lead electrode 43, see Fig.13 .

[0064] 4) The seat body 21 having the first microstructure 22 is welded to the pressure-sensitive film 20, and the pressure-sensitive film 20 is stretched by a fixture, and then the stretched pressure-sensitive film 20 is welded to the second convex ring 15a of the lower shell 16, so that after the upper shell 15 and the lower shell 16 are fixed, the pressure-sensitive film 20 separates the cavity into the first cavity 13 and the second cavity 14 which are not connected to each other, see Fig.15 The insulating substrate 30 and the pressure-sensitive film 20 are spaced apart, and the second microstructure 44 and the first microstructure 22 are opposite to each other, and the two form an interlocking microstructure. When the pressure-sensitive film 20 is deformed to the point where the second microstructure 44 and the first microstructure 22 are in contact and fit, an interlocking microstructure can be formed to achieve overload protection.

[0065] The method of the present invention, see Fig.14 , further comprising bonding the filter screen 70 to the air inlet 11 of the lower shell 16 body 10, and then welding the tube body 17 to the air inlet 11 by vacuum brazing to form an air inlet channel. Finally, the assembled upper shell 15 is welded to the lower shell 16 by vacuum brazing, and the getter 50 is activated to complete the preparation of the micro pressure sensor, see Fig.16 .

[0066] Compared with the existing micro-pressure sensors, the micro-pressure sensor with microstructure enhanced sensitivity of the present invention welds the pressure-sensitive film 20 and the base 21 together, and controls the distance between the base 21 and the inner electrode 41. As the external air pressure increases and exceeds the vacuum measurement range, the first microstructure 22 and the second microstructure 44 contact and fit together, preventing the pressure-sensitive film 20 from further displacement, thereby playing an overload protection role.

[0067] The present invention makes full use of the advantages of five-axis laser processing technology, processes protrusions and micropores on the opposite surfaces of the base 21 and the inner electrode 41, respectively, and adopts an interlocking microstructure, which greatly improves the detection sensitivity and accuracy of the micro pressure sensor, and can measure micro pressures as low as several Pa. Using five-axis laser processing technology, micropores with a high aspect ratio are processed inside the getter 50 to increase the specific surface area of ​​the getter 50, thereby improving the air absorption performance of the air absorption ratio, thereby improving the vacuum degree of the micro pressure sensor, and ensuring the working environment of the micro pressure sensor.

[0068] In the present invention, the terms "first", "second", "third", etc. are only used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence, nor can they be understood as indicating or implying relative importance. In the description, the directions or positional relationships indicated by "upper", "lower", "left", "right", "front", and "back" are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention, and are not intended to indicate or imply that the device referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as limiting the scope of protection of the present invention. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0069] In addition, in the description of this application, unless otherwise specified, "plurality" means two or more. "And / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. The character " / " generally indicates that the associated objects are in an "or" relationship.

[0070] The above is only a specific implementation of the present invention, but the design concept of the present invention is not limited to this. Any non-substantial changes to the present invention using this concept shall be deemed as an infringement of the protection scope of the present invention.

Claims

1. A micro pressure sensor with enhanced sensitivity, comprising a housing, wherein the housing is provided with a cavity and an air inlet, characterized in that: It also includes a pressure-sensitive film, an insulating substrate and an electrode group; the pressure-sensitive film is arranged in the cavity to separate it into a first cavity and a second cavity that are not connected to each other, the first cavity is connected to the air inlet, and the second cavity is a vacuum cavity; the insulating substrate is arranged in the second cavity and has a gap between the pressure-sensitive film; the electrode group is installed on the side of the insulating substrate opposite to the pressure-sensitive film to output a capacitance change signal generated by the deformation of the pressure-sensitive film, and a second microstructure is arranged on the side of the electrode group opposite to the pressure-sensitive film, and a first microstructure is arranged on the side of the pressure-sensitive film opposite to the second microstructure. The pressure-sensitive film is deformed under the pressure difference between the first cavity and the vacuum cavity, and when the pressure-sensitive film is deformed to the point where the second microstructure contacts and fits with the first microstructure, an interlocking microstructure can be formed to achieve overload protection.

2. A micro pressure sensor with enhanced sensitivity as claimed in claim 1, characterized in that: The electrode group includes an inner electrode and an outer electrode, the outer electrode is arranged around the inner electrode, the inner electrode and the outer electrode are respectively provided with lead-out electrodes passing through the second cavity to the outside of the shell, and the second microstructure is formed on the inner electrode.

3. A micro pressure sensor with enhanced sensitivity as claimed in claim 1, characterized in that: A seat is fixed on the pressure-sensitive film at a position relative to the electrode group, and the first microstructure is formed on the seat; when the pressure-sensitive film is not deformed, the distance between the second microstructure and the first microstructure is 100-150 um.

4. A micro pressure sensor with enhanced sensitivity as claimed in claim 2 or 3, characterized in that: The second microstructure includes a number of evenly distributed micropores, and the first microstructure includes a number of evenly distributed protrusions, or the second microstructure includes a number of evenly distributed protrusions, and the first microstructure includes a number of evenly distributed micropores; the protrusions are in the shape of a frustum, a prism or a pyramid; the micropores are concave holes adapted to the shape of the protrusions, and the height of the protrusions or the depth of the micropores is 50-200um.

5. The micro pressure sensor with enhanced sensitivity as claimed in claim 1, characterized in that: The shell includes an upper shell and a lower shell which are relatively fixed to form the cavity, the inner wall of the lower shell is provided with a circumferentially distributed first convex ring, and the pressure-sensitive film is relatively fixed to the first convex ring; the inner wall of the upper shell is provided with a circumferentially distributed second convex ring, the insulating base is relatively fixed to the second convex ring, and the air inlet is formed on the lower shell and is provided with a filter.

6. The micro pressure sensor with enhanced sensitivity as claimed in claim 1, characterized in that: At least one through hole is provided on a side of the second cavity away from the insulating substrate, the lead-out electrode of the electrode group is passed through the through hole, and a glass composition is filled between the through hole and the lead-out electrode.

7. The micro pressure sensor with enhanced sensitivity as claimed in claim 1, characterized in that: At least one groove is arranged on a side of the second cavity away from the insulating substrate, a getter is placed in the groove, and a barrier net is arranged on a side of the groove communicating with the second cavity.

8. A method for preparing a micro pressure sensor with enhanced sensitivity, characterized in that: The steps include: 1) Making a shell having a cavity and an air inlet; 2) using a five-axis laser to manufacture the second microstructure and the first microstructure on the electrode group and the base respectively; 3) welding the electrode group to the insulating substrate by vacuum brazing, and welding the insulating substrate to the cavity; 4) The seat body having the first microstructure is vacuum brazed with the pressure-sensitive film, and the pressure-sensitive film is stretched and vacuum brazed in the cavity of the shell to separate the cavity into a first cavity and a second cavity that are not connected to each other. The second cavity is configured as a vacuum cavity, and the insulating substrate is located in the second cavity and is spaced apart from the pressure-sensitive film. The second microstructure is opposite to the first microstructure, and when the pressure-sensitive film is deformed to the point where the second microstructure is in contact with the first microstructure and fits in with each other, an interlocking microstructure can be formed to achieve overload protection.

9. The method for preparing a micro pressure sensor with enhanced sensitivity as claimed in claim 8, characterized in that: Step 1) specifically includes preparing an upper shell and a lower shell respectively, and making a second convex ring, a groove and a through hole on the inner wall of the upper shell; making a first convex ring on the inner wall of the lower shell; in step 4), the pressure-sensitive film is welded and fixed to the first convex ring, and microholes are made on the getter by laser, the getter is placed in the groove and fixed by welding a barrier net, and in step 3), the insulating base is welded and fixed to the second convex ring, and after the lead-out electrode of the electrode group passes through the through hole, a glass composition is filled between the through hole and the lead-out electrode.

10. The method for preparing a micro-pressure sensor with enhanced sensitivity as claimed in claim 8, characterized in that: The electrode group includes an inner electrode and an outer electrode. In step 2), the second microstructure is manufactured on the surface of the inner electrode. In step 3), the inner electrode is welded to the insulating substrate, and the outer electrode is welded to the insulating substrate and surrounds the inner electrode.

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