Preparation method of flexible pressure sensor based on mechanical-electrical collaborative analysis

Abstract

The invention discloses a preparation method of a flexible pressure sensor based on mechanical-electrical collaborative analysis, and relates to the technical field of flexible electronic sensing, and the method comprises the following steps: S1, building a capacitive pressure sensor model; s2, performing finite element simulation on the capacitive pressure sensor; s3, respectively analyzing the influence of different microstructures, layer heights and array spacing on the performance of the capacitive pressure sensor; s4, evaluating performance indexes; s5, determining an optimal microstructure parameter; s6, preparing a capacitive pressure sensor, and performing performance comparison and actual measurement verification on the capacitive pressure sensor; parameterization scanning is carried out through a solid mechanics and electrostatics coupling simulation method, and an optimal geometric parameter combination is determined, so that a quantitative correlation model of microstructure deformation and capacitance response is established, and the physical essence that the stacked pyramid microstructure realizes capacitance response amplification through a hierarchical contact mechanism is revealed; and the measurement sensitivity and the measurement range of the flexible pressure sensor are improved.

Description

Technical Field

[0001] The present invention relates to the field of flexible electronic sensing technology, and in particular to a method for preparing a flexible pressure sensor based on mechanical-electrical collaborative analysis. Background Art

[0002] With the rapid development of electronic technology, micro-electromechanical systems and flexible electronic technology, capacitive pressure sensors have been widely used due to their simple structure, fast response speed and easy integration.

[0003] The current typical design of flexible capacitive pressure sensors adopts a sandwich structure, which consists of upper and lower metal electrodes and an intermediate dielectric layer. In traditional technologies, the homogeneous dielectric layer has insufficient sensitivity due to its small overall deformation. To this end, the industry has introduced microstructure designs such as long micro-ridges, cylinders or stacked pyramids on the surface of the dielectric layer, using local geometric deformation to amplify the capacitive response.

[0004] However, existing flexible capacitive pressure sensors still have certain defects. First, the flat dielectric layer only produces a small elastic deformation under uniform pressure, which makes it difficult to form the local strain gradient required for high-sensitivity detection; second, structures such as cylinders or long micro-ridges are prone to local stress concentration when under pressure, which will accelerate device fatigue failure. At the same time, the nonlinear characteristics of the capacitive response limit the detection range and cause nonlinear offset of the capacitive response; finally, there is a lack of research on the optimization of key parameters such as the layer height, spacing and shape gradient of the microstructure. The existing literature has not yet established a quantitative correlation model between parameter combinations and sensitivity and linear range, which makes it difficult for the sensor to have high sensitivity, wide linear range and high-voltage resistance.

[0005] Therefore, a preparation method of a flexible pressure sensor based on mechanical-electrical collaborative analysis is provided to solve the above problems. Summary of the Invention

[0006] The purpose of the present invention is to provide a preparation method of a flexible pressure sensor based on mechanical-electrical collaborative analysis. By stacking pyramid microstructure design and solid mechanics and electrostatic coupling simulation, the problems of insufficient sensitivity, stress concentration and blind parameter design of traditional flexible pressure sensors are solved, and a high-precision, low-cost flexible pressure sensor is provided.

[0007] To achieve the above objectives, the present invention provides a method for preparing a flexible pressure sensor based on mechanical-electrical collaborative analysis, comprising the following steps:

[0008] S1: Establish a capacitive pressure sensor model;

[0009] S2: Perform finite element simulation on capacitive pressure sensor;

[0010] S3: Analyze the effects of different microstructures on the performance of capacitive pressure sensors;

[0011] S4: Analyze the effects of different layer heights and array spacing on the performance of capacitive pressure sensors;

[0012] S5: Evaluation performance indicators;

[0013] S6: Determine the optimal microstructure parameters;

[0014] S7: Prepare capacitive pressure sensors and conduct performance comparison and actual measurement verification of the capacitive pressure sensors.

[0015] Preferably, step S1 specifically includes the following steps:

[0016] S11: constructing a sensor model, the sensor model including an upper copper electrode, a lower copper electrode, and a PDMS dielectric layer disposed between the upper copper electrode and the lower copper electrode;

[0017] S12: Four microstructure matrices were embedded in the PDMS dielectric layer. The four microstructure matrices were all set to a 3×3 matrix with an initial array spacing of 4 mm. The four microstructures included stacked pyramids and three contrasting structures, which were respectively set to long microridges, cylinders, and unstructured flat plates.

[0018] S13: Set the material parameters, set the elastic modulus of PDMS to 750 kPa, set the Poisson's ratio of PDMS to 0.49, and set the conductivity of the upper and lower copper electrodes to 5.998×10 7 S / m.

[0019] Preferably, in step S12, the stacked pyramid is set to a gradient structure that decreases layer by layer, the number of layers of the gradient structure is set to four, the size of the bottom layer is set to 4mm×4mm×1mm, the size of the next bottom layer is set to 3mm×3mm×1mm, the size of the next top layer is set to 2mm×2mm×1mm, and the size of the top layer is set to 1mm×1mm×1mm. Adjacent layers are connected by a transition slope, and the height of the transition slope is set to 0.5mm.

[0020] Preferably, in step S12, the bottom surface size of the long micro-ridge is set to 4 mm×4 mm, and the bottom surface radius of the cylinder is set to 2 mm.

[0021] Preferably, step S2 specifically includes the following steps:

[0022] S21: Set the lower copper electrode to the ground terminal in the COMSOL platform and perform a fixed constraint on the lower copper electrode;

[0023] S22: Apply a constant voltage of 1 V to the upper copper electrode in the COMSOL platform;

[0024] S23: Using the parametric sweep function, a pressure load of 0 kPa to 50 kPa is applied to the upper copper electrode in the vertical direction in stages, and the step size of the pressure load addition is set to 2.5 kPa.

[0025] Preferably, step S4 specifically includes the following steps:

[0026] S41: Activate the Solid Mechanics and Electrostatics modules, set the meshing to free tetrahedral elements, and set the minimum element size to 0.05 mm.

[0027] S42: obtaining the compression amount Δd of the microstructure by using the displacement field probe;

[0028] S43: Obtain the stress distribution inside the PDMS dielectric layer through the strain probe and calculate the contact area increment ΔA;

[0029] S44: Obtain the capacitance value between the upper copper electrode and the lower copper electrode using a relative capacitance change probe, and calculate the relative capacitance change rate y. The relative capacitance change rate y is specifically set to:

[0030]

[0031] Wherein, ΔC represents the capacitance change between the upper copper electrode and the lower copper electrode, and C0 represents the initial capacitance between the upper copper electrode and the lower copper electrode;

[0032] S45: Adjust the layer height and array spacing of the stacked pyramid respectively, set the adjustment range of the layer height to 0.5mm-1mm, and set the adjustment range of the array spacing to 2.5mm-4mm, and repeat steps S42 to S44;

[0033] S46: Analyze the effects of different microstructures, layer heights, and array spacing on the performance of capacitive pressure sensors by combining the microstructure compression Δd, contact area increment ΔA, and relative capacitance change rate y.

[0034] Preferably, step S5 specifically includes the following steps:

[0035] S51: Calculate the sensitivity of the capacitive pressure sensor, where the sensitivity is set as the ratio of the relative change rate y of the capacitance to the pressure load;

[0036] S52: Calculating the linearity R of a capacitive pressure sensor 2 , linearity R 2 The specific settings are:

[0037]

[0038] in, represents the predicted value of the fitted model, Indicates the average value of the relative rate of change of capacitance.

[0039] Preferably, in step S6, the optimal microstructure is a stacked pyramid, the layer height of the stacked pyramid is set to 1 mm, and the array spacing of the stacked pyramid is set to 4 mm.

[0040] Preferably, step S7 specifically includes the following steps:

[0041] S71: A PDMS mold was prepared by 3D printing, a stacked pyramid master mold was printed, and a PDMS prepolymer was poured. The PDMS prepolymer was set to Dow Corning SYLGARD 184, and the mixing ratio of the base glue and the curing agent in Dow Corning SYLGARD 184 was set to 10:1. The curing temperature was set to 80°C and the curing time was set to 2 hours. After the curing was completed, a stacked pyramid PDMS dielectric layer was obtained.

[0042] S72: Bonding the upper copper electrode and the lower copper electrode to the flexible substrate using conductive silver paste, respectively. The flexible substrate is set to PDMS. The lower copper electrode is grounded through a wire. The upper copper electrode is connected to the 1V AC excitation terminal of the LCR meter.

[0043] S73: embedding the stacked pyramid PDMS dielectric layer into a 3×3 matrix;

[0044] S74: Calibrate the capacitive pressure sensor using a universal testing machine and a capacitance test system.

[0045] Therefore, the present invention adopts the above-mentioned method for preparing a flexible pressure sensor based on mechanical-electrical collaborative analysis, which has the following beneficial effects:

[0046] (1) The parametric simulation model constructed based on the COMSOL platform shows that within the pressure range of 0-50 kPa, the stacked pyramid structure with optimal parameters achieves a relative capacitance change rate of 58%, which is 6.2 times higher than that of the traditional flat plate structure and significantly better than the long micro-ridge and cylindrical structures.

[0047] (2) The hierarchical release mechanism of the stacked pyramid layer deformation of the present invention controls the maximum stress value within 0.12 MPa, which is 21%-45% lower than the comparative structure, effectively avoiding local plastic deformation, making the device capacitance decay rate less than 3.8% after 100,000 cycle tests, significantly improving the service life;

[0048] (3) The systematic parameter scanning and multi-physics field linkage analysis in the technical solution of the present invention not only reveals the nonlinear mapping law between microstructure geometric parameters and capacitance response, and that every 0.5mm reduction in spacing can increase sensitivity by about 18%, but also establishes a layer height-spacing collaborative optimization model, enabling the sensor to achieve a linearity of 0.96 over a wide pressure range;

[0049] (4) The present invention provides a high-precision, low-cost sensing solution for wearable health monitoring devices. At the same time, the optimization method can be extended to the design of other microstructure sensors such as strain sensors and humidity sensors, and has wide applicability.

[0050] The method scheme of the present invention is further described in detail below through the drawings and examples. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 This is a flow chart of a method for preparing a flexible pressure sensor based on mechanical-electrical collaborative analysis of the present invention;

[0052] Figure 2 The structure diagram of four microstructure matrices of the PDMS dielectric layer of the present invention;

[0053] Figure 3 von-Mises stress distribution of four different microstructure sensors of the present invention;

[0054] Figure 4 The displacement simulation results of four different microstructure sensors of the present invention are shown in FIG.

[0055] Figure 5 The displacement curves and capacitance change curves of four different microstructure sensors of the present invention are shown in FIG. 1 , wherein (a) the displacement curves of four different microstructure sensors and (b) the capacitance change curves of four different microstructure sensors.

[0056] Figure 6 The structural diagrams of six stacked pyramid microstructures with different layer heights according to the present invention are shown;

[0057] Figure 7 von-Mises stress distribution of six stacked pyramid microstructure sensors with different layer heights according to the present invention;

[0058] Figure 8 The displacement simulation results of the stacked pyramid microstructure sensors with six different layer heights according to the present invention are shown in FIG.

[0059] Figure 9 The displacement curves and capacitance change curves of six different layer height stacked pyramid microstructure sensors of the present invention are shown in FIG. 1 , wherein (a) the displacement curves of six different layer height stacked pyramid microstructure sensors, and (b) the capacitance change curves of six different layer height stacked pyramid microstructure sensors.

[0060] Figure 10 The structure diagrams of four stacked pyramid microstructures with different spacings according to the present invention are as follows;

[0061] Figure 11 von-Mises stress distribution of four stacked pyramid microstructure sensors with different spacings according to the present invention;

[0062] Figure 12 The displacement simulation results of four different spacing stacked pyramid microstructure sensors of the present invention are shown in FIG.

[0063] Figure 13 The displacement curves and capacitance change curves of four different spacing stacked pyramid microstructure sensors of the present invention are shown in FIG. 1 , wherein (a) the displacement curves of four different spacing stacked pyramid microstructure sensors, and (b) the capacitance change curves of four different spacing stacked pyramid microstructure sensors.

[0064] Figure 14 This is a structural diagram of the capacitive pressure sensor of the present invention. DETAILED DESCRIPTION

[0065] The method scheme of the present invention is further described below through the drawings and examples.

[0066] Unless otherwise defined, technical terms or scientific terms used in the present invention shall have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs.

[0067] The words “include” or “comprising” and similar words used in the present invention mean that the elements before the word include the elements listed after the word, and do not exclude the possibility of also including other elements. The orientation or position relationship indicated by the terms “inside”, “outside”, “upper”, “lower”, etc. is based on the orientation or position relationship shown in the accompanying drawings. It is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it cannot be understood as a limitation of the present invention. When the absolute position of the described object changes, the relative position relationship may also change accordingly. In the present invention, unless otherwise clearly stipulated and limited, the terms such as “attachment” should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral whole; it can be directly connected or indirectly connected through an intermediate medium, and it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances.

[0068] Example

[0069] like Figure 1As shown, the present invention provides a method for preparing a flexible pressure sensor based on mechanical-electrical collaborative analysis, comprising the following steps:

[0070] S1: Establish a capacitive pressure sensor model;

[0071] Step S1 specifically includes the following steps:

[0072] S11: constructing a sensor model, the sensor model including an upper copper electrode, a lower copper electrode, and a PDMS dielectric layer disposed between the upper copper electrode and the lower copper electrode;

[0073] S12: Figure 2 As shown, four microstructure matrices are embedded in the PDMS dielectric layer. The four microstructure matrices are all set to a 3×3 matrix. The initial array spacing of the four microstructure matrices is all set to 4 mm. The four microstructures include stacked pyramids and three contrast structures. The three contrast structures are respectively set to long microridges, cylinders, and unstructured plates.

[0074] In step S12, the stacked pyramid is set to a gradient structure with decreasing layers. The number of layers of the gradient structure is set to four. The size of the bottom layer is set to 4 mm × 4 mm × 1 mm, the size of the next bottom layer is set to 3 mm × 3 mm × 1 mm, the size of the next top layer is set to 2 mm × 2 mm × 1 mm, and the size of the top layer is set to 1 mm × 1 mm × 1 mm. Adjacent layers are connected by a transition slope, and the height of the transition slope is set to 0.5 mm.

[0075] In step S12, the bottom surface size of the long micro-ridge is set to 4 mm × 4 mm, and the bottom surface radius of the cylinder is set to 2 mm;

[0076] S13: Set the material parameters, set the elastic modulus of PDMS to 750 kPa, set the Poisson's ratio of PDMS to 0.49, and set the conductivity of the upper and lower copper electrodes to 5.998×10 7 S / m.

[0077] S2: Perform finite element simulation on capacitive pressure sensor;

[0078] Step S2 specifically includes the following steps:

[0079] S21: Set the lower copper electrode to the ground terminal in the COMSOL platform and perform a fixed constraint on the lower copper electrode;

[0080] S22: Apply a constant voltage of 1 V to the upper copper electrode in the COMSOL platform to establish an electrostatic field;

[0081] S23: Using the parametric sweep function, a pressure load of 0 kPa to 50 kPa was applied vertically to the upper copper electrode in stages. The step size of the pressure load addition was set to 2.5 kPa to simulate a real pressure detection scenario.

[0082] S3: Analyze the effects of different microstructures on the performance of capacitive pressure sensors;

[0083] S4: Analyze the effects of different layer heights and array spacing on the performance of capacitive pressure sensors;

[0084] Step S4 specifically includes the following steps:

[0085] S41: An ultra-fine meshing strategy is used to ensure the accuracy of deformation and electric field calculations. The solid mechanics module and the electrostatics module are activated simultaneously. The meshing is set to free tetrahedral elements, and the minimum element size is set to 0.05 mm to ensure the analytical accuracy of the stress concentration area.

[0086] S42: obtaining the compression amount Δd of the microstructure by using the displacement field probe;

[0087] S43: If Figure 3-4 As shown, the stress distribution inside the PDMS dielectric layer is obtained by the strain probe, and the contact area increment ΔA is calculated;

[0088] S44: If Figure 5 As shown, the capacitance value between the upper copper electrode and the lower copper electrode is obtained by the relative capacitance change probe, and the relative capacitance change rate y is calculated. The relative capacitance change rate y is specifically set to:

[0089]

[0090] Wherein, ΔC represents the capacitance change between the upper copper electrode and the lower copper electrode, and C0 represents the initial capacitance between the upper copper electrode and the lower copper electrode;

[0091] S45: Figure 6-13 As shown, the layer height and array spacing of the stacked pyramid are adjusted respectively, the adjustment range of the layer height is set to 0.5mm-1mm, and the adjustment range of the array spacing is set to 2.5mm-4mm, and steps S42 to S44 are repeated;

[0092] S46: Combined with the microstructure compression Δd, contact area increment ΔA and relative capacitance change rate y, the effects of different microstructures, layer heights and array spacing on the performance of capacitive pressure sensors are analyzed, focusing on the gradient expansion characteristics of the contact area of the stacked pyramid structure during the step-by-step compression process and its influence mechanism on the equivalent dielectric constant.

[0093] Simulation results show that under a pressure load of 50kPa, stepped contact is generated between the stacked pyramid layers. The compression of the bottom layer is 0.32mm, the compression of the second bottom layer is 0.25mm, the shrinkage of the second top layer is 0.18mm, and the compression of the top layer is 0.12mm. The layer deformation causes the contact area to increase by 78% cumulatively, and the capacitance value increases from the initial 2.1pF to 5.8pF, with a capacitance change rate of 176% and a sensitivity of 0.85kPa. -1 .

[0094] S5: Evaluation performance indicators;

[0095] Step S5 specifically includes the following steps:

[0096] S51: Calculate the sensitivity of the capacitive pressure sensor, where the sensitivity is set as the ratio of the relative change rate y of the capacitance to the pressure load;

[0097] S52: Calculating the linearity R of a capacitive pressure sensor 2 , linearity R 2 The specific settings are:

[0098]

[0099] in, represents the predicted value of the fitted model, Indicates the average value of the relative rate of change of capacitance.

[0100] S6: Determine the optimal microstructure parameters;

[0101] In step S6, the optimal microstructure is a stacked pyramid. The layer height of the stacked pyramid is set to 1mm, and the array spacing of the stacked pyramid is set to 4mm. Simulation data show that when the layer height increases to 1mm, the deformation synergy effect between the pyramid levels is significantly enhanced, and the capacitance change rate increases by about 37%; when the spacing is reduced to 3mm, the synergistic deformation of the microstructure array effectively suppresses stress concentration, reducing the maximum stress value under 50kPa pressure by 21%. At this time, the sensor capacitance change rate reaches 58%, which is 6.2 times higher than that of the flat plate structure. The linearity of 0.96 is maintained in the range of 0-50kPa, and the stress peak is controlled within 0.12MPa to ensure structural durability.

[0102] S7: Prepare capacitive pressure sensors, and conduct performance comparison and field verification of the capacitive pressure sensors;

[0103] Step S7 specifically includes the following steps:

[0104] S71: A PDMS mold was prepared by 3D printing, a stacked pyramid master mold was printed, and a PDMS prepolymer was poured. The PDMS prepolymer was set to Dow Corning SYLGARD 184, and the mixing ratio of the base glue and the curing agent in Dow Corning SYLGARD 184 was set to 10:1. The curing temperature was set to 80°C and the curing time was set to 2 hours. After the curing was completed, a stacked pyramid PDMS dielectric layer was obtained.

[0105] S72: Bonding the upper copper electrode and the lower copper electrode to the flexible substrate using conductive silver paste, respectively. The flexible substrate is set to PDMS. The lower copper electrode is grounded via a wire. The upper copper electrode is connected to the 1V AC excitation terminal of the LCR meter to form a closed loop to monitor the change in capacitance value in real time.

[0106] S73: embedding the stacked pyramid PDMS dielectric layer into a 3×3 matrix;

[0107] S74: Calibrate the capacitive pressure sensor using a universal testing machine and a capacitance test system, such as Figure 14 As shown, the capacitive pressure sensor includes a dielectric layer with a microstructure and electrode layers arranged on both sides of the dielectric layer. The electrode layer is set as a conductive tape, and a wire is set on the conductive tape. An encapsulation layer is set on the other side of the conductive tape, and the encapsulation layer is specifically set as a polyimide film.

[0108] The measured data show that within the range of 0-50kPa, the capacitance change rate of the capacitive pressure sensor deviates from the simulation result by less than 8%, the maximum stress is 0.14MPa, the simulation prediction is 0.12MPa, and the linearity is 0.95;

[0109] Under the same measurement conditions, the capacitance change rate of the long micro-ridge structure is 89%, the stress peak is 0.27 MPa, and the capacitance change rate of the cylindrical structure is 73%, the stress peak is 0.31 MPa;

[0110] Compared with the long micro-ridge structure and the cylindrical structure, the stacked pyramid structure has a 94% increase in sensitivity and a 48% reduction in stress concentration.

[0111] Therefore, the present invention adopts the above-mentioned preparation method of flexible pressure sensors based on mechanical-electrical collaborative analysis, and through systematic simulation verification, reveals the physical essence of the stacked pyramid microstructure to achieve capacitive response amplification through a hierarchical contact mechanism, providing a replicable design paradigm for the engineering realization of high-sensitivity and wide-range flexible pressure sensors.

[0112] Finally, it should be noted that the above embodiments are only used to illustrate the method scheme of the present invention and not to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, ordinary method personnel in this field should understand that they can still modify or replace the method scheme of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified method scheme to deviate from the spirit and scope of the method scheme of the present invention.

Claims

1. A method for preparing a flexible pressure sensor based on mechanical-electrical collaborative analysis, characterized in that: The following steps are involved: S1: Establish a capacitive pressure sensor model; S2: Perform finite element simulation on capacitive pressure sensor; S3: Analyze the effects of different microstructures on the performance of capacitive pressure sensors; S4: Analyze the effects of different layer heights and array spacing on the performance of capacitive pressure sensors; S5: Evaluation performance indicators; S6: Determine the optimal microstructure parameters; S7: Prepare capacitive pressure sensors and conduct performance comparison and actual measurement verification of the capacitive pressure sensors.

2. The method for preparing a flexible pressure sensor based on mechanical-electrical collaborative analysis according to claim 1, characterized in that: Step S1 specifically includes the following steps: S11: constructing a sensor model, the sensor model including an upper copper electrode, a lower copper electrode, and a PDMS dielectric layer disposed between the upper copper electrode and the lower copper electrode; S12: Four microstructure matrices were embedded in the PDMS dielectric layer. The four microstructure matrices were all set to a 3×3 matrix with an initial array spacing of 4 mm. The four microstructures included stacked pyramids and three contrasting structures, which were respectively set to long microridges, cylinders, and unstructured flat plates. S13: Set the material parameters, set the elastic modulus of PDMS to 750 kPa, set the Poisson's ratio of PDMS to 0.49, and set the conductivity of the upper and lower copper electrodes to 5.998×10 7 S / m.

3. The method for preparing a flexible pressure sensor based on mechanical-electrical collaborative analysis according to claim 2, characterized in that: In step S12, the stacked pyramid is set to a gradient structure that decreases layer by layer. The number of layers of the gradient structure is set to four. The size of the bottom layer is set to 4mm×4mm×1mm, the size of the next bottom layer is set to 3mm×3mm×1mm, the size of the next top layer is set to 2mm×2mm×1mm, and the size of the top layer is set to 1mm×1mm×1mm. Adjacent layers are connected by a transition slope, and the height of the transition slope is set to 0.5mm.

4. The method for preparing a flexible pressure sensor based on mechanical-electrical collaborative analysis according to claim 2, characterized in that: In step S12, the bottom surface size of the long micro-ridge is set to 4 mm×4 mm, and the bottom surface radius of the cylinder is set to 2 mm.

5. The method for preparing a flexible pressure sensor based on mechanical-electrical collaborative analysis according to claim 1, characterized in that: Step S2 specifically includes the following steps: S21: Set the lower copper electrode to the ground terminal in the COMSOL platform and perform a fixed constraint on the lower copper electrode; S22: Apply a constant voltage of 1 V to the upper copper electrode in the COMSOL platform; S23: Using the parametric sweep function, a pressure load of 0 kPa to 50 kPa is applied to the upper copper electrode in the vertical direction in stages, and the step size of the pressure load addition is set to 2.5 kPa.

6. The method for preparing a flexible pressure sensor based on mechanical-electrical collaborative analysis according to claim 1, characterized in that: Step S4 specifically includes the following steps: S41: Activate the Solid Mechanics and Electrostatics modules, set the meshing to free tetrahedral elements, and set the minimum element size to 0.05 mm. S42: obtaining the compression amount Δd of the microstructure by using the displacement field probe; S43: Obtain the stress distribution inside the PDMS dielectric layer through the strain probe and calculate the contact area increment ΔA; S44: Obtain the capacitance value between the upper copper electrode and the lower copper electrode using a relative capacitance change probe, and calculate the relative capacitance change rate y. The relative capacitance change rate y is specifically set to: Wherein, ΔC represents the capacitance change between the upper copper electrode and the lower copper electrode, and C0 represents the initial capacitance between the upper copper electrode and the lower copper electrode; S45: Adjust the layer height and array spacing of the stacked pyramid respectively, set the adjustment range of the layer height to 0.5mm-1mm, and set the adjustment range of the array spacing to 2.5mm-4mm, and repeat steps S42 to S44; S46: Analyze the effects of different microstructures, layer heights, and array spacing on the performance of capacitive pressure sensors by combining the microstructure compression Δd, contact area increment ΔA, and relative capacitance change rate y.

7. The method for preparing a flexible pressure sensor based on mechanical-electrical collaborative analysis according to claim 1, characterized in that: Step S5 specifically includes the following steps: S51: Calculate the sensitivity of the capacitive pressure sensor, where the sensitivity is set as the ratio of the relative change rate y of the capacitance to the pressure load; S52: Calculating the linearity R of a capacitive pressure sensor 2 , linearity R 2 The specific settings are: in, represents the predicted value of the fitted model, Indicates the average value of the relative rate of change of capacitance.

8. The method for preparing a flexible pressure sensor based on mechanical-electrical collaborative analysis according to claim 1, characterized in that: In step S6 , the optimal microstructure is a stacked pyramid, the layer height of the stacked pyramid is set to 1 mm, and the array pitch of the stacked pyramid is set to 4 mm.

9. The method for preparing a flexible pressure sensor based on mechanical-electrical collaborative analysis according to claim 1, characterized in that: Step S7 specifically includes the following steps: S71: A PDMS mold was prepared by 3D printing, a stacked pyramid master mold was printed, and a PDMS prepolymer was poured. The PDMS prepolymer was set to Dow Corning SYLGARD 184, and the mixing ratio of the base glue and the curing agent in Dow Corning SYLGARD 184 was set to 10:

1. The curing temperature was set to 80°C and the curing time was set to 2 hours. After the curing was completed, a stacked pyramid PDMS dielectric layer was obtained. S72: Bonding the upper copper electrode and the lower copper electrode to the flexible substrate using conductive silver paste, respectively. The flexible substrate is set to PDMS. The lower copper electrode is grounded through a wire. The upper copper electrode is connected to the 1V AC excitation terminal of the LCR meter. S73: embedding the stacked pyramid PDMS dielectric layer into a 3×3 matrix; S74: Calibrate the capacitive pressure sensor using a universal testing machine and a capacitance test system.

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