Double-layer capacitance differential flexible pressure sensor and preparation method thereof

Abstract

The invention discloses a double-layer capacitance differential flexible pressure sensor and a preparation method thereof, and relates to the technical field of wind pressure measurement. The double-layer capacitance differential flexible pressure sensor comprises a pressure difference sensing unit, and the pressure difference sensing unit comprises a strain assembly, a first positioning block, a second positioning block, a first electrode, a second electrode and a lead-out wire. The strain assembly includes an intermediate electrode, a first insulating film, and a second insulating film. The first positioning block is provided with a first groove, a first positioning face and a first vent hole, and the second positioning block is provided with a second groove, a second positioning face and a second vent hole. The first electrode is installed at the bottom of the first groove, and the first electrode and the intermediate electrode form a first capacitor. The second electrode is installed at the bottom of the second groove, and the second electrode and the middle electrode form a second capacitor. Compared with the prior art, the double-layer capacitance differential flexible pressure sensor has the advantages that the sensitivity of the pressure sensor is improved, and meanwhile, the linearity of the pressure sensor is ensured in a full range.

Description

Technical Field

[0001] The present invention relates to the technical field of wind pressure measurement, and in particular to a double-layer capacitance differential flexible pressure sensor and a preparation method thereof. Background Art

[0002] Drones play an increasingly important role in human production and scientific research activities, and the measurement of surface pressure distribution is particularly important for the flight control of drones. At present, the widely used pressure measurement method is the embedded sensing system, including pressure measuring holes distributed on the nose or wings, air bleed pipes and pressure sensors, but there are problems such as complex system, signal lag, damage to the fuselage, and poor reliability at low speed.

[0003] Existing single-capacitor flexible pressure sensors usually show a sharp decrease in sensitivity under negative pressure. The reason is that after the strain film is deformed upward, the electrode spacing increases, resulting in a decrease in the sensitivity of the sensor and nonlinearity of the sensor output. Summary of the invention

[0004] The purpose of the present invention is to provide a double-layer capacitance differential flexible pressure sensor and a preparation method thereof, so as to solve the problems existing in the above-mentioned related technologies, improve the sensitivity of the pressure sensor and ensure its linearity within the full range.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] The present invention discloses a double-layer capacitance differential flexible pressure sensor, comprising a pressure difference sensing unit, wherein the pressure difference sensing unit comprises:

[0007] A strain assembly, the strain assembly comprising an intermediate electrode capable of bending and deformation, a first insulating film located on a first side of the intermediate electrode, and a second insulating film located on a second side of the intermediate electrode;

[0008] a first positioning block located at a first side of the strain assembly, the first positioning block having a first groove, a first positioning surface and a first vent hole; the first groove is used to provide a deformation space so that the strain assembly can bend toward the first side; the first positioning surface is located around the first groove and is used to contact the strain assembly from the first side; the first vent hole communicates with the inner and outer sides of the first groove;

[0009] A second positioning block located on the second side of the strain assembly, the second positioning block having a second groove, a second positioning surface and a second vent hole; the second groove is used to provide a deformation space so that the strain assembly can bend toward the second side; the second groove is directly opposite to the first groove; the second positioning surface is located around the second groove and is used to contact the strain assembly from the second side; the second vent hole communicates with the inner and outer sides of the second groove;

[0010] A first electrode installed at the bottom of the first groove, wherein the first electrode and the middle electrode form a first capacitor;

[0011] A second electrode installed at the bottom of the second groove, the second electrode and the middle electrode forming a second capacitor;

[0012] Leading wires include a middle leading wire, a first leading wire and a second leading wire; one end of the middle leading wire is connected to the first electrode, one end of the second leading wire is connected to the second electrode, and one end of the middle leading wire is connected to the middle electrode.

[0013] Preferably, one end of the first vent hole connected to the first groove is located at the bottom of the first groove; and one end of the second vent hole connected to the second groove is located at the bottom of the second groove.

[0014] Preferably, the first positioning block is provided with a plurality of the first grooves, and the second positioning block is provided with a plurality of the second grooves, so as to obtain a plurality of the differential pressure sensing units; the double-layer capacitor differential flexible pressure sensor also includes a connecting component located on the second side of the second positioning block, the connecting component having a connecting groove and a third positioning surface; the connecting groove is respectively connected to the second air holes of the plurality of the differential pressure sensing units, so that the second grooves of the plurality of the differential pressure sensing units have a common air pressure, which is called the reference air pressure; the third positioning surface is located around the connecting groove, and is used to contact the second positioning block from the second side.

[0015] Preferably, the double-layer capacitor differential flexible pressure sensor also includes an absolute pressure sensor chip, at least part of which is located in the second air vent or in the connecting groove, for measuring the reference air pressure; the lead-out wire also includes a chip lead-out wire, one end of which is connected to the absolute pressure sensor chip.

[0016] Preferably, the number of the differential pressure sensing units is 3 to 20.

[0017] Preferably, the connecting component includes a flow channel layer located on the second side of the second positioning block, and a base located on the second side of the flow channel layer; the flow channel layer is provided with a connecting groove, the connecting groove passes through the first side and the second side of the flow channel layer, and the connecting groove provides the side wall of the connecting groove; the third positioning surface is located on the first side of the flow channel layer and is located around the connecting groove; the base closes the second side of the connecting groove, and the base provides the bottom of the connecting groove.

[0018] Preferably, at least one of the first insulating film, the second insulating film, the first positioning block, the second positioning block, the flow channel layer, and the substrate is made of polyimide.

[0019] Preferably, the first positioning block and the first insulating film, the second insulating film and the second positioning block, the second positioning block and the flow channel layer, and the flow channel layer and the substrate are all bonded and connected.

[0020] Preferably, the bonding material is AD hot melt adhesive.

[0021] The present invention also discloses a method for preparing a double-layer capacitance differential flexible pressure sensor, which is used to prepare the above-mentioned double-layer capacitance differential flexible pressure sensor, comprising the following steps:

[0022] Spin-coat a polyimide solution on a silicon wafer and solidify it, process an intermediate electrode through a lift-off process, and then spin-coat a layer of polyimide film to obtain a strain component;

[0023] A plurality of first grooves and a plurality of first vent holes are processed on the polyimide film by milling to obtain a first positioning block; a plurality of second grooves and a plurality of second vent holes are processed on the polyimide film by milling to obtain a second positioning block; a connecting groove is processed on the polyimide film by laser etching to obtain a flow channel layer;

[0024] Arrange at least part of the absolute pressure sensor chip in the connecting groove; connect one end of the middle lead wire to the first electrode, connect one end of the second lead wire to the second electrode, connect one end of the middle lead wire to the middle electrode, and connect one end of the chip lead wire to the absolute pressure sensor chip;

[0025] By means of vacuum hot pressing bonding, the substrate, the flow channel layer, the second positioning block and the strain assembly are first connected in sequence; then, by means of vacuum hot pressing bonding, the first positioning block and the strain assembly are connected as a whole to obtain a double-layer capacitive differential flexible pressure sensor.

[0026] Compared with the related art, the present invention has achieved the following technical effects:

[0027] Compared with the existing single-capacitor flexible pressure sensor, the present invention can maintain linearity and sensitivity when the external air pressure is higher than the reference air pressure and when the external air pressure is lower than the reference air pressure through differential processing of two capacitors.

[0028] The present invention utilizes a small-diameter pressure measuring hole to accurately measure the pressure difference, thereby accurately locating the position angle of the pressure measuring point on the aircraft without affecting the sensitivity.

[0029] The preparation method of the present invention realizes the rapid preparation of a double-layer capacitance differential flexible pressure sensor by combining a flexible circuit board with a micro-machining process. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or related technologies, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0031] Figure 1 Schematic diagram of a double-layer capacitance differential flexible pressure sensor according to an embodiment of the present invention;

[0032] Figure 2 A state diagram of a pressure difference sensing unit;

[0033] Figure 3 is another state schematic diagram of the pressure difference sensing unit;

[0034] Figure 4 for Figure 1 Schematic diagram after adding absolute pressure sensor chip;

[0035] Figure 5 for Figure 4 Exploded view of the structure;

[0036] Figure 6 Schematic diagram of a method for preparing a double-layer capacitive differential flexible pressure sensor according to an embodiment of the present invention.

[0037] Figure 7 is a comparison diagram of the first capacitor and the second capacitor;

[0038] Figure 8 This is a comparison diagram of three measurements of the first capacitance;

[0039] Fig. 9 This is a comparison chart of three measurements of the second capacitance.

[0040] In the figure: 100-double-layer capacitor differential flexible pressure sensor; 1-strain assembly; 2-first positioning block; 3-second positioning block; 4-first electrode; 5-second electrode; 6-lead wire; 7-absolute pressure sensor chip; 8-flow channel layer; 9-substrate; 11-middle electrode; 12-first insulating film; 13-second insulating film; 21-first groove; 31-second groove; 81-circulation slot; P1-external air pressure; P0-reference air pressure; C1-first capacitor; C2-second capacitor. DETAILED DESCRIPTION

[0041] The following will be combined with the drawings in 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.

[0042] The purpose of the present invention is to provide a double-layer capacitance differential flexible pressure sensor and a preparation method thereof, so as to solve the problems existing in the above-mentioned related technologies, improve the sensitivity of the pressure sensor and ensure its linearity within the full range.

[0043] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0044] Reference Figures 1 to 9 This embodiment provides a double-layer capacitive differential flexible pressure sensor 100, including a pressure difference sensing unit, the pressure difference sensing unit includes a strain assembly 1, a first positioning block 2, a second positioning block 3, a first electrode 4, a second electrode 5 and a lead wire 6.

[0045] The strain assembly 1 is a "sandwich" structure, including an intermediate electrode 11 capable of bending and deformation, a first insulating film 12 located on a first side of the intermediate electrode 11, and a second insulating film 13 located on a second side of the intermediate electrode 11. When the intermediate electrode 11 is bent and deformed, the first insulating film 12 and the second insulating film 13 follow the deformation.

[0046] The first positioning block 2 is located at the first side of the strain assembly 1, and the first positioning block 2 has a first groove 21, a first positioning surface and a first vent. The first groove 21 is used to provide a deformation space so that the strain assembly 1 can bend toward the first side. The first positioning surface is located around the first groove 21 and is used to contact the strain assembly 1 from the first side. The first vent connects the inner and outer sides of the first groove 21 so that the air pressure inside and outside the first groove 21 is the same.

[0047] The second positioning block 3 is located on the second side of the strain assembly 1, and the second positioning block 3 has a second groove 31, a second positioning surface and a second vent. The second groove 31 is used to provide a deformation space so that the strain assembly 1 can bend toward the second side, and the second groove 31 is directly opposite to the first groove 21. The second positioning surface is located around the second groove 31 and is used to contact the strain assembly 1 from the second side. The second vent connects the inner and outer sides of the second groove 31 so that the air pressure inside and outside the second groove 31 is the same.

[0048] The first electrode 4 is installed at the bottom of the first groove 21 , and the first electrode 4 and the middle electrode 11 form a first capacitor.

[0049] The second electrode 5 is installed at the bottom of the second groove 31 , and the second electrode 5 and the middle electrode 11 form a second capacitor.

[0050] The lead wires 6 include a middle lead wire, a first lead wire and a second lead wire. One end of the middle lead wire is connected to the first electrode 4, one end of the second lead wire is connected to the second electrode 5, and one end of the middle lead wire is connected to the middle electrode 11.

[0051] The working principle of the double-layer capacitance differential flexible pressure sensor 100 of this embodiment is as follows:

[0052] The first groove 21 is connected to the external space, and its air pressure is called the external air pressure. The second groove 31 is connected to a closed cavity, and its air pressure is called the reference air pressure, which remains unchanged. When the external air pressure is greater than the reference air pressure, the strain component 1 bulges toward the second groove 31 under the action of the pressure difference, the distance between the intermediate electrode 11 and the first electrode 4 increases, the first capacitance decreases, the distance between the intermediate electrode 11 and the second electrode 5 decreases, and the second capacitance increases. When the external air pressure is less than the reference air pressure, the strain component 1 bulges toward the first groove 21 under the action of the pressure difference, the distance between the intermediate electrode 11 and the first electrode 4 decreases, the first capacitance increases, the distance between the intermediate electrode 11 and the second electrode 5 increases, and the second capacitance decreases. The first insulating film 12 is used to avoid the short circuit caused by the contact between the intermediate electrode 11 and the first electrode 4, and the second insulating film 13 is used to avoid the short circuit caused by the contact between the intermediate electrode 11 and the second electrode 5. The external device (impedance meter) measures the changes in the first capacitance and the second capacitance through the intermediate lead wire, the first lead wire and the second lead wire, thereby calculating the pressure difference between the external air pressure and the reference air pressure.

[0053] Compared with the existing single-capacitor flexible pressure sensor, this embodiment can maintain linearity and sensitivity when the external air pressure is higher than the reference air pressure and when the external air pressure is lower than the reference air pressure through differential processing of two capacitors.

[0054] As a possible example, in this embodiment, one end of the first vent hole connected to the first groove 21 is located at the bottom of the first groove 21, and one end of the second vent hole connected to the second groove 31 is located at the bottom of the second groove 31. However, the actual implementation is not limited to this. For example, the first vent hole can also be set on the side wall of the first groove 21.

[0055] As a possible example, in this embodiment, a plurality of first grooves 21 are provided on the first positioning block 2, and a plurality of second grooves 31 are provided on the second positioning block 3, so as to obtain a plurality of differential pressure sensing units. The double-layer capacitive differential flexible pressure sensor 100 also includes a connecting component located on the second side of the second positioning block 3, and the connecting component has a connecting groove and a third positioning surface. The connecting grooves are respectively connected to the second vents of the plurality of differential pressure sensing units, so that the second grooves 31 of the plurality of differential pressure sensing units have a common air pressure, namely, a reference air pressure. The third positioning surface is located around the connecting groove, and is used to contact the second positioning block 3 from the second side.

[0056] Since each differential pressure sensing unit has the same reference air pressure, after the pressure difference measured by each differential pressure sensing unit is calculated, any two pressure differences are subtracted to obtain the pressure difference of the first grooves 21 of the corresponding two differential pressure sensing units.

[0057] As a possible example, in this embodiment, the double-layer capacitor differential flexible pressure sensor 100 further includes an absolute pressure sensor chip 7, at least part of which is located in the second vent hole or the connecting groove, for measuring the reference air pressure. The lead wire 6 further includes a chip lead wire, one end of which is connected to the absolute pressure sensor chip 7.

[0058] The external device measures the reference air pressure through the chip lead wire, and then combines the pressure difference measured by each differential pressure sensor unit to calculate the air pressure of the first groove 21 measured by each differential pressure sensor unit, and then obtains the distribution of the external air pressure, thereby realizing multi-point absolute pressure measurement based on a single absolute pressure sensor chip 7 and a differential pressure sensor array.

[0059] As a possible example, in this embodiment, the number of the differential pressure sensing units is 3 to 20. For example, the number of the differential pressure sensing units is 6. Those skilled in the art may also select other numbers according to different actual needs.

[0060] As a possible example, in this embodiment, the connecting component includes a flow channel layer 8 located on the second side of the second positioning block 3, and a base 9 located on the second side of the flow channel layer 8. The flow channel layer 8 is provided with a connecting groove 81, which runs through the first side and the second side of the flow channel layer 8 (the connecting groove is only provided on the first side of the connecting component), and the connecting groove 81 provides the side wall of the connecting groove. The third positioning surface is located on the first side of the flow channel layer 8 and is located around the connecting groove 81. The base 9 closes the second side of the connecting groove 81, and the base 9 provides the bottom of the connecting groove.

[0061] As a possible example, in this embodiment, at least one of the first insulating film 12, the second insulating film 13, the first positioning block 2, the second positioning block 3, the flow channel layer 8, and the substrate 9 is made of polyimide, and more preferably, all of them are made of polyimide.

[0062] As a possible example, in this embodiment, the first positioning block 2 and the first insulating film 12, the second insulating film 13 and the second positioning block 3, the second positioning block 3 and the flow channel layer 8, and the flow channel layer 8 and the substrate 9 are all bonded together. Exemplarily, the bonding material may be AD hot melt adhesive.

[0063] Reference Figure 8 , Fig. 9 In the three tests, the double-layer capacitor differential flexible pressure sensor 100 showed good repeatability, but the capacitance showed obvious nonlinearity in the full range. The first capacitor was insensitive to negative pressure, while the second capacitor was insensitive to positive pressure. This is because after the strain component 1 is deformed, when the distance between the two electrodes increases, the sensitivity of the sensor will decrease sharply. The sensor output is differentially processed to obtain the differential test results. Figure 7 After differential processing, the sensor shows high sensitivity and linearity over the full range. This verifies the advantages of the double-layer capacitor differential structure over the traditional single capacitor structure, especially when it is necessary to measure positive and negative pressures during the change of the wing angle of attack. Combining the maximum sensitivity of the sensor and the noise level when the pressure difference is 0, the minimum resolution of the two sensors can be calculated to be 24mPa and 26mPa.

[0064] Reference Figure 6 This embodiment also provides a method for preparing a double-layer capacitance differential flexible pressure sensor, which is used to prepare the above-mentioned double-layer capacitance differential flexible pressure sensor 100, comprising the following steps:

[0065] A polyimide solution is spin-coated on a silicon wafer (eg, 8000 rpm, 60 seconds) and cured, the middle electrode 11 is processed by a lift-off process, and then a layer of polyimide film is spin-coated to obtain the strain component 1 .

[0066] A plurality of first grooves 21 and a plurality of first vent holes are processed on the polyimide film by milling to obtain a first positioning block 2. A plurality of second grooves 31 and a plurality of second vent holes are processed on the polyimide film by milling to obtain a second positioning block 3. A connecting groove 81 is processed on the polyimide film by laser etching to obtain a flow channel layer 8.

[0067] At least part of the absolute pressure sensor chip 7 is arranged in the connecting groove 81. One end of the middle lead wire is connected to the first electrode 4, one end of the second lead wire is connected to the second electrode 5, one end of the middle lead wire is connected to the middle electrode 11, and one end of the chip lead wire is connected to the absolute pressure sensor chip 7.

[0068] By vacuum hot pressing bonding, the substrate 9, the flow channel layer 8, the second positioning block 3 and the strain assembly 1 are first connected in sequence (the order of description in this sentence) as a whole. Then, by vacuum hot pressing bonding, the first positioning block 2 and the strain assembly 1 are connected as a whole to obtain a double-layer capacitive differential flexible pressure sensor 100.

[0069] For example, during the first bonding process, the air pressure is 5 Pa, the bonding pressure is 0.1 MPa, the bonding temperature is 200° C. and kept for 30 minutes, then cooled naturally to room temperature, the device is peeled off from the silicon wafer, and the first bonding is completed. Then the first positioning block 2 is also processed by hot pressing bonding.

[0070] Exemplarily, the vacuum hot-pressing bonding process uses AD hot-melt adhesive as the bonding layer, and its melting point is 180°C.

[0071] Exemplarily, the thickness of the first insulating film 12 and the second insulating film 13 is 1.5 μm, and the thickness of the intermediate electrode 11 is 100 nm. The flow channel layer 8 uses a polyimide film with AD glue on both sides, wherein the polyimide layer is 60 μm thick, and the AD glue layers on both sides are 10 μm thick, for a total of 80 μm. The first positioning block 2 uses a polyimide film with AD glue on the second side, wherein the AD glue layer is 10 μm thick, and the polyimide layer is 25 μm thick. The second positioning block 3 uses a polyimide film with AD glue on the first side, wherein the AD glue layer is 10 μm thick, and the polyimide layer is 25 μm thick.

[0072] The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only used to help understand the method and core ideas of the present invention. At the same time, for those skilled in the art, according to the ideas of the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A double-layer capacitance differential flexible pressure sensor, characterized in that: The invention comprises a pressure difference sensing unit, wherein the pressure difference sensing unit comprises: A strain assembly, the strain assembly comprising an intermediate electrode capable of bending and deformation, a first insulating film located on a first side of the intermediate electrode, and a second insulating film located on a second side of the intermediate electrode; a first positioning block located at a first side of the strain assembly, the first positioning block having a first groove, a first positioning surface and a first vent hole; the first groove is used to provide a deformation space so that the strain assembly can bend toward the first side; the first positioning surface is located around the first groove and is used to contact the strain assembly from the first side; the first vent hole communicates with the inner and outer sides of the first groove; A second positioning block located on the second side of the strain assembly, the second positioning block having a second groove, a second positioning surface and a second vent hole; the second groove is used to provide a deformation space so that the strain assembly can bend toward the second side; the second groove is directly opposite to the first groove; the second positioning surface is located around the second groove and is used to contact the strain assembly from the second side; the second vent hole communicates with the inner and outer sides of the second groove; A first electrode installed at the bottom of the first groove, wherein the first electrode and the middle electrode form a first capacitor; A second electrode installed at the bottom of the second groove, the second electrode and the middle electrode forming a second capacitor; Leading wires include a middle leading wire, a first leading wire and a second leading wire; one end of the middle leading wire is connected to the first electrode, one end of the second leading wire is connected to the second electrode, and one end of the middle leading wire is connected to the middle electrode.

2. The double-layer capacitance differential flexible pressure sensor according to claim 1, characterized in that: One end of the first vent hole connected to the first groove is located at the bottom of the first groove; and one end of the second vent hole connected to the second groove is located at the bottom of the second groove.

3. The double-layer capacitance differential flexible pressure sensor according to claim 2, characterized in that: The first positioning block is provided with a plurality of the first grooves, and the second positioning block is provided with a plurality of the second grooves, so as to obtain a plurality of the differential pressure sensing units; the double-layer capacitance differential flexible pressure sensor further comprises a connecting component located on the second side of the second positioning block, the connecting component having a connecting groove and a third positioning surface; the connecting groove is respectively connected to the second vents of the plurality of the differential pressure sensing units, so that the second grooves of the plurality of the differential pressure sensing units have a common air pressure, which is called a reference air pressure; The third positioning surface is located around the communicating groove and is used to contact the second positioning block from the second side.

4. The double-layer capacitance differential flexible pressure sensor according to claim 3, characterized in that: It also includes an absolute pressure sensor chip, at least part of which is located in the second vent hole or the connecting groove, and is used to measure the reference air pressure; the lead-out wire also includes a chip lead-out wire, one end of which is connected to the absolute pressure sensor chip.

5. The double-layer capacitance differential flexible pressure sensor according to claim 3, characterized in that: The number of the differential pressure sensing units is 3 to 20.

6. The double-layer capacitance differential flexible pressure sensor according to claim 3, characterized in that: The connecting component includes a flow channel layer located on the second side of the second positioning block, and a base located on the second side of the flow channel layer; the flow channel layer is provided with a connecting groove, the connecting groove runs through the first side and the second side of the flow channel layer, and the connecting groove provides the side wall of the connecting groove; the third positioning surface is located on the first side of the flow channel layer and is located around the connecting groove; the base closes the second side of the connecting groove, and the base provides the bottom of the connecting groove.

7. The double-layer capacitance differential flexible pressure sensor according to claim 6, characterized in that: At least one of the first insulating film, the second insulating film, the first positioning block, the second positioning block, the flow channel layer, and the substrate is made of polyimide.

8. The double-layer capacitance differential flexible pressure sensor according to claim 6, characterized in that: The first positioning block and the first insulating film, the second insulating film and the second positioning block, the second positioning block and the flow channel layer, and the flow channel layer and the substrate are all bonded and connected.

9. The double-layer capacitance differential flexible pressure sensor according to claim 8, characterized in that: The bonding material is AD hot melt adhesive.

10. A method for preparing a double-layer capacitance differential flexible pressure sensor, characterized in that: The method for preparing the double-layer capacitance differential flexible pressure sensor according to any one of claims 6 to 9 comprises the following steps: A polyimide solution is spin-coated on a silicon wafer and cured, an intermediate electrode is processed by a lift-off process, and a layer of polyimide film is spin-coated to obtain a strain component; A plurality of first grooves and a plurality of first vent holes are processed on the polyimide film by milling to obtain a first positioning block; a plurality of second grooves and a plurality of second vent holes are processed on the polyimide film by milling to obtain a second positioning block; a connecting groove is processed on the polyimide film by laser etching to obtain a flow channel layer; Arrange at least part of the absolute pressure sensor chip in the connecting groove; connect one end of the middle lead wire to the first electrode, connect one end of the second lead wire to the second electrode, connect one end of the middle lead wire to the middle electrode, and connect one end of the chip lead wire to the absolute pressure sensor chip; By means of vacuum hot pressing bonding, the substrate, the flow channel layer, the second positioning block and the strain assembly are first connected in sequence; then, by means of vacuum hot pressing bonding, the first positioning block and the strain assembly are connected as a whole to obtain a double-layer capacitive differential flexible pressure sensor.

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