Flexible stretchable ferroelectric electret multi-axial-force vector sensor and preparation method thereof

Abstract

The invention discloses a flexible stretchable ferroelectric electret multi-axial-force vector sensor and a preparation method, and relates to the technical field of flexible electronic devices. The sensor comprises four sensing units at different positions, each sensing unit is internally provided with an inclined cavity, the inclination directions of the cavities of the sensing units are different, every two of the four sensing units form a group, the two sensing units in the same group are arranged along a diagonal line, and the projections of the two groups of sensing units on a plane are rectangular; the sensing unit is composed of an upper module and a lower module. Through the innovative asymmetric inclined cavity array structure and the design of the sensing units in different directions, the cavity deformation of the ferroelectric electret film and the corresponding electric dipole moment change show remarkable anisotropy, sensing and distinguishing of three-dimensional multi-axial force vectors can be achieved, for example, normal pressure and tangential shear force can be effectively distinguished, and the sensing precision is improved. The technical bottleneck that a traditional sensor is difficult to realize multi-modal sensing in a complex mechanical scene is broken through.

Description

Technical Field

[0001] The present invention relates to the technical field of flexible electronic devices, and in particular to a flexible and stretchable ferroelectric electret multi-axis force vector sensor and a preparation method thereof. Background Art

[0002] With the rapid development of flexible electronic devices in the fields of robot tactile perception and wearable health monitoring, the demand for three-dimensional multi-axis force vector sensors that can simultaneously detect normal and tangential forces is becoming increasingly urgent. Traditional multi-dimensional force sensors mostly use piezoresistive or capacitive sensing principles, and achieve multi-axis detection through a stacked structure or arrayed electrode design. However, this type of design has significant drawbacks: Structural complexity: stacked sensors need to integrate multiple layers of sensitive units and isolation structures, resulting in increased device thickness and reduced flexibility; signal crosstalk: multi-axis mechanical components produce coupling effects at the stacking interface, and the electrical signals of each axis interfere with each other, making it difficult to achieve precise decoupling.

[0003] Ferroelectric electret sensors have become an emerging solution to the above problems due to their advantages such as low power consumption and high charge stability. However, the existing technology still has a fundamental bottleneck: the symmetrical design of the cavity structure leads to an isotropic piezoelectric response. When subjected to three-dimensional multi-axial forces, the mechanical components in different directions induce similar cavity deformation patterns, making it impossible to effectively distinguish between normal pressure and tangential shear force in the output electrical signal, ultimately leading to the failure of multi-axis vector analysis. To this end, we propose a flexible and stretchable ferroelectric electret multi-axis force vector sensor and its preparation method. Summary of the Invention

[0004] The purpose of the present invention is to provide a flexible and stretchable ferroelectric electret multi-axis force vector sensor and a preparation method, which are used to develop a single-layer flexible sensor architecture that can suppress signal cross-interference from a physical structure and achieve precise decoupling of force vectors.

[0005] To achieve the above objectives, the present invention provides the following technical solutions: a flexible and stretchable ferroelectric electret multi-axis force vector sensor, comprising four sensing units at different positions, each of the sensing units having an inclined cavity therein, each of the sensing units having a different inclination direction, the four sensing units being arranged in a group of two, the two sensing units in the same group being arranged diagonally, and the projections of the two groups of sensing units on a plane being rectangular;

[0006] The sensing unit is composed of an upper module and a lower module. The bottom of the upper module is evenly provided with a plurality of first through slots, and the top of the lower module is evenly provided with a plurality of second through slots. Both ends of the first through slots and the second through slots are connected, and the top is set to be open.

[0007] The first through-groove and the second through-groove are both arranged obliquely along the width direction of the upper module and the lower module, and when the upper module and the lower module are spliced ​​together, the first through-groove and the second through-groove form a complete inclined cavity, and when the upper module and the lower module are spliced ​​together, a ferroelectric electret film is formed, and flexible stretchable electrodes and wires are installed on the upper and lower sides of the ferroelectric electret film;

[0008] When a single sensing unit is subjected to compression, the cavity dipole moment decreases, and when the sensor is subjected to tension, the cavity dipole moment increases, thereby achieving the perception and resolution of force vectors;

[0009] When the four sensor units are subjected to pressure at the same time, all four sensor units output signals of the same size. When subjected to shear force, the output signals of the diagonal sensor units in the same group increase and decrease, respectively, thereby realizing the perception and discrimination of three-dimensional force vectors.

[0010] Furthermore, the two sensing unit cavities at diagonal positions in the same group are tilted in opposite directions;

[0011] In the two groups of sensor units, the first group of sensor units is translated and then rotated 90 degrees along the geometric center to obtain the second group of sensor units.

[0012] Furthermore, the angle between the axis of the complete inclined cavity formed by the first through slot and the second through slot of each sensing unit and the horizontal direction is set to be 30°-60°.

[0013] Furthermore, there are multiple cavities, and the multiple cavities are evenly arranged along the length direction of the ferroelectret film, and the cross-sectional shape of the cavity is set to be a parallelogram or an ellipse.

[0014] Furthermore, when the cross-sectional shape of the cavity is set to be an ellipse, the aspect ratio of the ellipse is 2:1 to 5:1.

[0015] Furthermore, the long diameter of the cavity is set to range from 100 to 200 μm, and the short diameter range is set to range from 20 to 100 μm.

[0016] Furthermore, the volume of the cavity accounts for 25%-45% of the volume of the ferroelectret film.

[0017] Furthermore, the flexible stretchable electrode is prepared by using a mixture of PEDOT:PSS and a flexible polymer.

[0018] Furthermore, the upper module and the lower module are made of polydimethylsiloxane or ecoflex material.

[0019] According to a second aspect of the present invention, the present invention provides a method for preparing a flexible and stretchable ferroelectric electret multi-axis force vector sensor, which is used to prepare the above-mentioned flexible and stretchable ferroelectric electret multi-axis force vector sensor, comprising the following steps:

[0020] S1. Use 3D printing technology to prepare the upper and lower molds, using polylactic acid as the material;

[0021] S2. The PDMS prepolymer and the curing agent were thoroughly mixed in a mass ratio of 10:1 to form a homogeneous slurry;

[0022] S3. Pour the slurry into the upper and lower molds, respectively, and then cure at 150°C for 5–10 minutes to form the upper and lower modules. The upper and lower modules are then joined together using the inherent viscosity of the PDMS material to form a ferroelectret film with a tilted pore array structure.

[0023] S4. Prepare flexible stretchable electrodes by thoroughly mixing a PEDOT:PSS solution with PDMS in a 1:5 mass ratio. These electrodes are then mounted on the upper and lower sides of the ferroelectret film, with wires extending therefrom to connect to a microprocessor, completing the assembly of the sensing unit.

[0024] In step S4, a flexible stretchable electrode is prepared as follows:

[0025] S41. The PEDOT:PSS solution was mixed with a 10 wt % tritonx-100 solution and a 7 wt % EG solution;

[0026] S42. Then, a homogeneous slurry formed by mixing PDMS prepolymer and curing agent was added; the ratio of PDMS prepolymer to PEDOT:PSS was 5:1 and stirred for 20 minutes until uniformly mixed;

[0027] S43. Use a scraper to apply the mixed slurry on the PET substrate, wait for 1 hour to allow the PEDOT:PSS and PDMS to separate, and finally solidify in a vacuum drying oven to form

[0028] S5. Assemble sensor units with different tilt directions at diagonal positions. Combine two sets of sensor units with different tilt directions at diagonal positions to form a flexible and stretchable ferroelectric electret three-dimensional force vector sensor.

[0029] S6. Apply a high voltage electric field to the ferroelectret film to polarize it, so that a directional electric dipole is formed in the cavity.

[0030] The present invention has at least the following beneficial effects:

[0031] 1. Through the innovative design of an asymmetric tilted cavity array structure, the present invention makes the cavity deformation and corresponding electric dipole moment change of the ferroelectric electret film show significant anisotropy, which can realize the perception and resolution of force vectors. Through the assembly of force sensing units, the perception and resolution of three-dimensional force vectors are realized, breaking through the technical bottleneck of traditional sensors that are difficult to achieve multimodal perception in complex mechanical scenarios.

[0032] 2. Optimized combination of materials and structures: The ferroelectric electret matrix is ​​constructed using polydimethylsiloxane (PDMS), combined with a tilted cavity array structure, and a conductive polymer PEDOT:PSS and PDMS composite is used as a transparent, flexible, stretchable electrode. This achieves an optimized combination of material properties and structural functions, providing good flexibility and stretchability. It can be widely used in fields such as intelligent robot tactile feedback, real-time monitoring of biological motion posture, and human-computer interaction, and has broad application prospects.

[0033] 3. High sensitivity and linear response: By controlling the angle between the cavity axis and the normal direction of the sensor surface, the cavity diameter, the aspect ratio, and the overall porosity, a linear relationship between mechanical deformation and electrical response is established, which improves the sensitivity of the sensor and can effectively detect and distinguish pressure and tension in different directions.

[0034] 4. Anisotropic sensing response: The asymmetric deformation of the tilted cavity causes a change in the distribution of electric dipoles, resulting in significant differences in polarization intensity and characteristics, thereby achieving force vector resolution. The difference in output signals of force sensing units in different tilt directions enables feature extraction of three-dimensional mechanical components, providing the sensor with an anisotropic sensing response and enhancing the detection capability of multi-axis force vectors.

[0035] Of course, any product implementing the present invention does not necessarily need to achieve all of the advantages described above at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a three-dimensional schematic diagram of the ferroelectret thin film structure of a single sensing unit in the present invention.

[0037] Figure 2 Schematic diagram of two sensing units in the same group with cavities tilted in different directions in the present invention;

[0038] Figure 3 Schematic diagram of the positional relationship between two groups of sensor units in the present invention;

[0039] Figure 4 This is an overall schematic diagram of the flexible and stretchable ferroelectric electret multi-axis force vector sensor assembled in the present invention;

[0040] Figure 5 Schematic diagram of the working principle of a single sensing unit in the present invention.

[0041] Reference numerals:

[0042] 1. Upper mold; 2. Lower mold; 3. Upper module; 4. Lower module; 5. Ferroelectric electret film; 6. Flexible stretchable electrode; 7. Wire; 8. First through-slot; 9. Second through-slot; 10. Cavity; 11, 12. Two sensing units in the first group with cavities tilted in different directions; 13, 14. Two sensing units in the second group with cavities tilted in different directions; 15. Assembled flexible stretchable ferroelectric electret multi-axis force vector sensor; DETAILED DESCRIPTION

[0043] The following will be combined with the accompanying drawings in the embodiments of the present disclosure to clearly and completely describe the technical solutions in the embodiments of the present disclosure. Obviously, the embodiments described are only part of the embodiments of the present disclosure, not all of the embodiments. Based on the embodiments of the present disclosure, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present disclosure.

[0044] Example 1:

[0045] See also Figure 1-Figure 5 The present invention provides a technical solution for use in the field of wearable electronic devices: a flexible and stretchable ferroelectric electret multi-axis force vector sensor, comprising four sensing units (11, 12, 13, 14) at different positions, wherein the sensing units have an inclined cavity (10) inside, and the inclined direction of each sensing unit cavity (10) is different, and the four sensing units form a group of two, and the two sensing units in the same group are arranged along a diagonal line, and the projections of the two groups of sensing units on the plane are rectangular;

[0046] Each sensing unit includes an upper module 3 and a lower module 4. The bottom of the upper module 3 is uniformly provided with a plurality of first through slots 8, and the top of the lower module 4 is uniformly provided with a plurality of second through slots 9. Both ends of the first through slots 8 and the second through slots 9 are connected, and the top is set to be open;

[0047] The first through-slot 8 and the second through-slot 9 are arranged obliquely along the width direction of the upper module 3 and the lower module 4, and when the upper module 3 and the lower module 4 are spliced ​​together, the first through-slot 8 and the second through-slot 9 form a complete inclined cavity 10. This structure is anisotropic compared to the horizontal cavity and can identify forces in different directions, such as the positive and negative semi-axis directions of the x-axis. After the upper module 3 and the lower module 4 are spliced ​​together, a ferroelectric electret film 5 is formed. Flexible stretchable electrodes 6 are installed on the upper and lower sides of the ferroelectric electret film 5.

[0048] When a single sensing unit is subjected to compression, the dipole moment of the cavity 10 decreases, and when the sensor is subjected to tension, the dipole moment of the cavity 10 increases, thereby achieving the perception and resolution of the force vector;

[0049] When the four sensor units are subjected to pressure at the same time, all four sensor units output signals of the same size. When subjected to shear force, the output signals of the diagonal sensor units in the same group increase and decrease, respectively, thereby realizing the perception and discrimination of three-dimensional force vectors.

[0050] According to the technical solution of this embodiment, the angle between the axis of the complete inclined cavity 10 formed by the first through-slot 8 and the second through-slot 9 and the horizontal direction is set to 30°-60°. There are multiple cavities 10, and the multiple cavities 10 are evenly arranged along the length direction of the ferroelectret film 5. Based on the structural design of the asymmetric inclined cavity 10, the piezoelectric properties of the ferroelectret are anisotropic, so that the normal and tangential multi-dimensional stress vectors can be distinguished, breaking through the key technical bottleneck of the flexible sensor in complex mechanical scenarios. The multimodal perception is difficult to achieve. When the axis of the cavity 10 is at an angle of 30°-60° to the horizontal direction, the directional arrangement and polarization state of the cavity charge are more susceptible to mechanical deformation, thereby achieving effective regulation of the electrical performance, so that the sensor produces obvious electrical signal differences under different force conditions. At the same time, it is also convenient to establish a linear relationship between mechanical deformation and electrical response, so that the output signal of the sensor shows a good linear correspondence with the magnitude and direction of the force, which is conducive to the subsequent accurate measurement and analysis of the force vector.

[0051] Furthermore, the cross-sectional shape of the cavity 10 is set to a parallelogram or an ellipse. This embodiment does not make any specific restrictions here and can be selected according to actual conditions. For the convenience of description, this embodiment uses an elliptical cross-section as an example to illustrate the scheme. It should be noted that when the cross-sectional shape of the cavity 10 is set to an ellipse, the aspect ratio of the ellipse is 2:1 to 5:1.

[0052] According to the technical solution of this embodiment, the long diameter range of the elliptical cavity 10 is set to 100-200μm, and the short diameter range is 20-100μm. Within this range, the size of the cavity 10 is small enough to achieve high sensitivity and large enough to generate a strong electrical signal. When the cavity 10 is deformed, the polarization charge distributed inside it changes more obviously, thereby improving the output signal strength and signal-to-noise ratio of the sensor. In addition, the cavity 10 in this size range can better reflect the anisotropic deformation when arranged at an angle. When the sensor is subjected to forces in different directions, the asymmetric deformation of the cavity 10 is more obvious, resulting in an increase in the difference in the change of the electric dipole moment, thereby more effectively realizing the distinction of three-dimensional multi-axis force vectors.

[0053] In the technical solution of this embodiment, the volume ratio of the cavity 10 to the volume ratio of the ferroelectric electret film 5 is 25%–45%. Within the volume ratio range of 25%–45%, the number and distribution of the cavities 10 in the ferroelectric electret film 5 are relatively reasonable, which can effectively enhance the responsiveness to external forces. When subjected to external forces, the deformation of the cavity 10 is more significant, thereby generating a greater change in the electrical signal and improving the sensitivity of the sensor. In addition, the appropriate volume ratio of the cavity 10 can provide sufficient space for storing charge and form a regularly oriented giant dipole during the polarization process. The volume ratio of 25%–45% makes the charge distribution in the cavity more uniform and the polarization effect more significant, thereby enhancing the electrical response and improving the performance of the sensor.

[0054] Furthermore, the flexible stretchable electrode 6 is made from a mixture of PEDOT:PSS and a flexible polymer. PEDOT:PSS itself has good flexibility and conductivity, but when used alone, it may experience a decrease in conductivity under high strain. By mixing it with a flexible polymer (such as PDMS), the mechanical properties of the electrode can be significantly improved, allowing it to maintain stable electrical performance under complex deformations such as stretching and bending.

[0055] Furthermore, the upper module 3 and the lower module 4 are made of polydimethylsiloxane or ecoflex material. Using PDMS or ecoflex material to prepare the upper module 3 and the lower module 4 can optimize the comprehensive performance in terms of flexibility, stretchability, chemical stability, biocompatibility, processing performance and cost-effectiveness, providing a wide range of choices and a good foundation for the application of sensors.

[0056] like Figure 2 As shown, when the sensing unit described in this embodiment is subjected to horizontal or vertical pressure, the micropores undergo asymmetric deformation with different compression rates, and the cavity dipole moment decreases; conversely, when subjected to horizontal / vertical tension, the micropores undergo asymmetric deformation with different stretching rates, causing the internal dipole moment to increase, thereby realizing the perception and discrimination of force vectors based on a single-layer structure.

[0057] When the flexible stretchable ferroelectric electret sensor 17 is subjected to pressure, the four sensor units all output signals of the same magnitude. When the sensor is subjected to shear force, the diagonal sensor unit outputs signals that increase and decrease, thereby realizing the perception and discrimination of three-dimensional force vectors.

[0058] In summary, the present invention uses an innovative asymmetric inclined cavity 10 array structure design to make the cavity deformation and corresponding electric dipole moment change of the ferroelectric electret film 5 show significant anisotropy, which can realize the perception and resolution of force vectors, and combine sensing units in different directions to realize the perception and resolution of three-dimensional force vectors (for example, effectively distinguishing normal pressure from tangential shear force), breaking through the technical bottleneck of traditional sensors that are difficult to achieve multimodal perception in complex mechanical scenarios.

[0059] Example 2:

[0060] According to a second aspect of the present invention, the present invention provides a method for preparing a flexible and stretchable ferroelectric electret multi-axis force vector sensor, which is used to prepare the above-mentioned flexible and stretchable ferroelectric electret multi-axis force vector sensor, comprising the following steps:

[0061] S1. Use 3D printing technology to prepare upper mold 1 and lower mold 2, respectively, using polylactic acid as the material;

[0062] S2. The PDMS prepolymer and the curing agent were thoroughly mixed in a mass ratio of 10:1 to form a homogeneous slurry;

[0063] S3. Pour the slurry into upper mold 1 and lower mold 2, respectively, and then cure at 150°C for 5–10 minutes to form upper module 3 and lower module 4. The upper and lower modules 3 and 4 are then joined together using the inherent viscosity of the PDMS material to form a ferroelectret film 5 with a tilted pore array structure.

[0064] S4. A flexible stretchable electrode 6 is prepared by thoroughly mixing a PEDOT:PSS solution with PDMS in a mass ratio of 1:5. The flexible stretchable electrodes 6 are mounted on the upper and lower sides of the ferroelectret film, and lead wires 7 are connected to the microprocessor to complete the assembly of the sensing unit.

[0065] The flexible stretchable electrode 6 is prepared as follows:

[0066] S41. The PEDOT:PSS solution was mixed with a 10 wt % tritonx-100 solution and a 7 wt % EG solution;

[0067] S42. Then, a homogeneous slurry formed by mixing PDMS prepolymer and curing agent was added; the ratio of PDMS prepolymer to PEDOT:PSS was 5:1 and stirred for 20 minutes until uniformly mixed;

[0068] S43. Use a scraper to apply the mixed slurry on a PET substrate, wait for 1 hour for the PEDOT:PSS and PDMS to phase separate, and finally solidify in a vacuum drying oven;

[0069] S5. The sensor units with different tilt directions are assembled at diagonal positions, and two groups of sensor units with different tilt directions of the cavity 10 are combined together to form a flexible and stretchable ferroelectric electret three-dimensional force vector sensor;

[0070] S6. Apply a high voltage of –15 kV to –25 kV to the sensor for corona polarization, with a needle tip distance of 3–5 cm and a polarization time of 3–10 minutes. This forms regularly oriented giant dipoles within the ferroelectret cavity 10, i.e., the upper and lower surfaces of each cavity 10 carry equal amounts of opposite charges. This in turn generates induced charges on the upper and lower surfaces of the sensor, giving it a piezoelectric effect.

[0071] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus.

[0072] For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances. When an element is referred to as being "assembled on", "installed on", "fixed on" or "set on" another element, it can be directly on the other element or there can be a central element. When an element is considered to be "connected" to another element, it can be directly connected to the other element or there can be a central element at the same time. The terms "vertical", "horizontal", "up", "down", "left", "right" and similar expressions used herein are for illustrative purposes only and are not intended to be the only embodiment.

[0073] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

[0074] Throughout this specification, references to terms such as "one embodiment," "example," or "specific example" indicate that a specific feature, structure, material, or characteristic described in conjunction with that embodiment or example is included in at least one embodiment or example of the present disclosure. In this specification, schematic representations of these terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

Claims

1. A flexible and stretchable ferroelectric electret multi-axis force vector sensor, characterized in that: The invention comprises four sensing units at different positions, wherein the sensing units have an inclined cavity (10) inside, and the inclined direction of each sensing unit cavity (10) is different. The four sensing units form a group of two, and the two sensing units in the same group are arranged along a diagonal line, and the projection of the two groups of sensing units on the plane is a rectangle; The sensing unit is composed of an upper module (3) and a lower module (4); a plurality of first through slots (8) are evenly provided on the bottom of the upper module (3); a plurality of second through slots (9) are evenly provided on the top of the lower module (4); both ends of the first through slots (8) and the second through slots (9) are connected, and the top is set to be open; The first through groove (8) and the second through groove (9) are both arranged obliquely along the width direction of the upper module (3) and the lower module (4), and when the upper module (3) and the lower module (4) are spliced ​​together, the first through groove (8) and the second through groove (9) form a complete inclined cavity (10), and after the upper module (3) and the lower module (4) are spliced ​​together, a ferroelectric electret film (5) is formed, and flexible stretchable electrodes (6) and wires (7) are installed on both the upper and lower sides of the ferroelectric electret film (5); When a single sensing unit is subjected to a compressive force, the dipole moment of the cavity (10) decreases, and when the sensor is subjected to a tensile force, the dipole moment of the cavity (10) increases, thereby achieving perception and resolution of the force vector; When the four sensor units are subjected to pressure at the same time, all four sensor units output signals of the same size. When subjected to shear force, the output signals of the diagonal sensor units in the same group increase and decrease, respectively, thereby realizing the perception and discrimination of three-dimensional force vectors.

2. The flexible and stretchable ferroelectret multi-axis force vector sensor according to claim 1, characterized in that: The two sensing unit cavities (10) at diagonal positions in the same group have opposite tilt directions; In the two groups of sensor units, the first group of sensor units is translated and then rotated 90 degrees along the geometric center to obtain the second group of sensor units.

3. The flexible and stretchable ferroelectret multi-axis force vector sensor according to claim 2, characterized in that: The angle between the axis of the complete inclined cavity (10) formed by the first through slot (8) and the second through slot (9) of each sensing unit and the horizontal direction is set to 30°-60°.

4. The flexible and stretchable ferroelectret multi-axis force vector sensor according to claim 3, characterized in that: There are multiple cavities (10), and the multiple cavities (10) are evenly arranged along the length direction of the ferroelectret film (5), and the cross-sectional shape of the cavity (10) is set to be a parallelogram or an ellipse.

5. The flexible and stretchable ferroelectret multi-axis force vector sensor according to claim 4, characterized in that: When the cross-sectional shape of the cavity (10) is set to be an ellipse, the aspect ratio of the ellipse is 2:1 to 5:

1.

6. The flexible and stretchable ferroelectret multi-axis force vector sensor according to claim 5, characterized in that: The long diameter of the cavity (10) is set to be in the range of 100-200 μm, and the short diameter is in the range of 20-100 μm.

7. The flexible and stretchable ferroelectret multi-axis force vector sensor according to claim 6, characterized in that: The volume ratio of the cavity (10) to the volume ratio of the ferroelectret film (5) is 25%-45%.

8. The flexible and stretchable ferroelectret multi-axis force vector sensor according to claim 7, characterized in that: The flexible stretchable electrode (6) is prepared by using a mixture of PEDOT:PSS and a flexible polymer.

9. The flexible and stretchable ferroelectret multi-axis force vector sensor according to claim 8, characterized in that: The upper module (3) and the lower module (4) are made of polydimethylsiloxane or ecoflex material.

10. A method for preparing a flexible and stretchable ferroelectric electret multi-axis force vector sensor, for preparing the flexible and stretchable ferroelectric electret multi-axis force vector sensor according to any one of claims 1 to 9, characterized in that: The following steps are involved: S1. Using 3D printing technology to prepare the upper mold (1) and the lower mold (2), the material is polylactic acid; S2. The PDMS prepolymer and the curing agent were thoroughly mixed in a mass ratio of 10:1 to form a homogeneous slurry; S3. Pour the slurry into the upper mold (1) and the lower mold (2), respectively, and then cure at 150°C for 5-10 minutes to form an upper module (3) and a lower module (4). Then, the upper module (3) and the lower module (4) are spliced ​​together using the viscosity of the PDMS material itself to form a ferroelectric electret film (5) with an inclined pore array structure; S4. PEDOT:PSS solution and PDMS are fully mixed in a mass ratio of 1:5 to prepare a flexible stretchable electrode (6), the flexible stretchable electrode (6) is respectively installed on the upper and lower sides of the ferroelectric electret film, and the lead wires (7) are connected to the microprocessor to complete the assembly of the sensing unit; In step S4, a flexible stretchable electrode (6) is prepared as follows: S41. The PEDOT:PSS solution was mixed with a 10 wt % tritonx-100 solution and a 7 wt % EG solution; S42. Then, a homogeneous slurry formed by mixing PDMS prepolymer and curing agent was added; the ratio of PDMS prepolymer to PEDOT:PSS was 5:1 and stirred for 20 minutes until uniformly mixed; S43. Use a scraper to apply the mixed slurry on a PET substrate, wait for 1 hour for the PEDOT:PSS and PDMS to phase separate, and finally solidify in a vacuum drying oven; S5. Assembling the sensing units with different tilt directions at diagonal positions, combining two groups of sensor units with different tilt directions of the cavity (10) at diagonal positions to form a flexible and stretchable ferroelectric electret three-dimensional force vector sensor; S6. Applying a high voltage electric field to the ferroelectret film (5) for polarization, so that a directional electric dipole is formed in the cavity (10).

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