Micro-structure flexible pressure sensor based on crease evolution and design method

Abstract

The invention belongs to the technical field of flexible sensors, and discloses a microstructure flexible pressure sensor based on crease evolution and a design method. The sensor comprises an upper electrode, a lower electrode and a sensitive layer located between the upper electrode and the lower electrode, and the sensitive layer is composed of a flat plate and a plurality of microstructure units. The microstructure unit is of a polyhedral structure, comprises a basic unit and a derivative unit thereof, and is designed through a crease evolution strategy. The design method comprises the steps that a basic unit is unfolded into a two-dimensional fold, after geometric characteristics are analyzed, derivative folds are generated through an amplification or reduction similar evolution strategy, and then the derivative folds are folded into a three-dimensional microstructure unit. Through a systematic design method and an innovative crease evolution technology, the problem of randomness in the design of the micro-structure flexible pressure sensor is solved, the performance and reliability of the sensor are remarkably improved, and the method has important theoretical value and practical application significance.

Description

Technical Field

[0001] The present invention belongs to the technical field of flexible sensors, and particularly relates to a microstructured flexible pressure sensor based on crease evolution and a design method thereof. Background Art

[0002] A flexible pressure sensor that can help a soft robot sense changes in contact pressure is an indispensable part of an intelligent flexible system. With the continuous development of intelligent requirements, higher requirements are put forward for performance indicators of flexible pressure sensors such as wide working range, high linearity, and customizable sensitivity. More research focuses on various strategies aimed at improving sensing performance. Among them, the micron-scale morphological structure design of the sensitive layer or electrode layer is considered a promising method to improve the performance of flexible pressure sensors. For example, by controllably introducing microstructures with highly regular shapes (such as pyramids or micro-hemispheres), or replicating naturally occurring microscopic structure templates (such as pollen grains, petals, human skin, and sandpaper) to introduce them into the active layer of the flexible pressure sensor. However, due to the lack of clear guidance based on rational design, the realization of target performance by these methods is random. Therefore, it is necessary to introduce a definite microstructure design method and further determine the morphological and spatial parameters based on appropriate theoretical calculations. Summary of the Invention

[0003] The purpose of the present invention is to provide a microstructured flexible pressure sensor based on crease evolution and a design method thereof, so as to solve the technical problem that the microstructure design method of the existing flexible pressure sensor lacks clear guidance based on rational design, resulting in randomness in design.

[0004] To solve the above technical problems, the specific technical solutions of a microstructured flexible pressure sensor based on crease evolution and a design method thereof of the present invention are as follows: A microstructured flexible pressure sensor based on crease evolution includes a sensitive layer. The sensitive layer includes a flat plate and a series of microstructural units. Each microstructural unit is connected by the flat plate. The microstructural unit is a series of polyhedral units with a polygonal bottom surface, isosceles triangular sides, and a single vertex. The polyhedral unit is obtained from a basic unit based on a derivative design method.

[0005] Furthermore, the microstructured flexible pressure sensor further includes an upper electrode and a lower electrode. The sensitive layer is connected between the upper electrode and the lower electrode, and the upper electrode and the lower electrode are wrapped with a packaging layer.

[0006] Furthermore, the upper electrode and the lower electrode are made of a conductive material.

[0007] Furthermore, the sensitive layer is an ion-conductive hydrogel material mixed with polyvinyl alcohol and anhydrous magnesium chloride, or a PDMS elastomer doped with a conductive material.

[0008] Further, when the base of the polyhedron unit is a regular quadrilateral and the isosceles triangles on the sides are equilateral triangles, it is defined as a 4-1 type basic unit, where 4 represents the number of vertices of the base polygon and 1 represents the number of vertices; when the base of the polyhedron unit is a regular quadrilateral and the ratio of the height to the base of the isosceles triangle on the side is greater than it is defined as a 4-1 type I derivative unit, where 4 represents the number of vertices of the base polygon and 1 represents the number of vertices; when the base of the polyhedron unit is a regular quadrilateral and the ratio of the height to the base of the isosceles triangle on the side is less than it is defined as a 4-1 type II derivative unit, where 4 represents the number of vertices of the base polygon and 1 represents the number of vertices; when the base of the polyhedron unit is an octagon and the sides are eight isosceles triangles, it is defined as an 8-1 type derivative unit, where 8 represents the number of vertices of the base polygon and 1 represents the number of vertices; the 4-1 type I derivative unit, 4-1 type II derivative unit, and 8-1 type derivative unit are obtained from the 4-1 type basic unit based on the derivative design method.

[0009] The present invention also discloses a derivative design method for the micro-structure unit of a micro-structure flexible pressure sensor based on crease evolution, including the following steps: Step 1: Unfold the 4-1 type basic unit along the edges, from three dimensions to two dimensions, to obtain a two-dimensional crease pattern with a regular quadrilateral in the center and four isosceles triangles around it, which is defined as a two-dimensional basic crease; Step 2: Analyze the geometric characteristics of the two-dimensional basic crease, and define the circumcircles of the regular quadrilateral and the four isosceles triangles as basic circles. The surrounding basic circles are all tangent to two adjacent basic circles, and the tangent points are the vertices of the central regular quadrilateral; Step 3: Based on the similarity evolution strategy, the two-dimensional basic crease evolves to obtain a two-dimensional 4-1 type I derivative crease, a two-dimensional 4-1 type II derivative crease, and a two-dimensional 8-1 type derivative crease; Step 4: Fold the two-dimensional derivative crease along the sides of the quadrilateral or octagon to obtain a 4-1 type I derivative unit, a 4-1 type II derivative unit, and an 8-1 type derivative unit.

[0010] Further, the two-dimensional 4-1 type I derivative crease in Step 3 is obtained by the enlarged similarity evolution strategy of taking the inner intersection points from the two-dimensional basic crease. The two-dimensional 4-1 type I derivative crease includes a regular quadrilateral and four isosceles triangles with the bases coinciding with the sides of the regular quadrilateral; the enlarged similarity evolution strategy of taking the inner intersection points is based on the basic circles in the two-dimensional basic crease. Without changing the positions of the centers of the basic circles, the radii of the basic circles are synchronously enlarged to obtain new enlarged derivative basic circles. The adjacent derivative basic circles intersect at two inner and outer intersection points P in and P out and select four inner intersection pointsP in Connect them in sequence to obtain the bottom quadrilateral of the 4-1 type derivative polyhedron unit. Make perpendicular bisectors on each side of the bottom quadrilateral, and take the far intersection points of the perpendicular bisectors and the four enlarged derivative basic circles as the vertices of the isosceles triangles on the sides. Connect them in sequence to obtain four isosceles triangles.

[0011] Furthermore, the two-dimensional 4-1 type II derivative crease described in step 3 is obtained by the enlarged similar evolution strategy of taking external intersection points from the two-dimensional basic crease. The two-dimensional 4-1 type II derivative crease includes a regular quadrilateral and four isosceles triangles with the bases coinciding with the sides of the regular quadrilateral; the enlarged similar evolution strategy of taking external intersection points is based on the basic circles in the two-dimensional basic crease. Without changing the positions of the centers of the basic circles, synchronously enlarge the radii of the basic circles to obtain new enlarged derivative basic circles. Adjacent derivative basic circles intersect at two internal and external intersection points P in and P out , select four external intersection points P out Connect them in sequence to obtain the bottom quadrilateral of the 4-1 type II derivative polyhedron unit. Make perpendicular bisectors on each side of the bottom quadrilateral, and take the far intersection points of the perpendicular bisectors and the four enlarged derivative basic circles as the vertices of the isosceles triangles on the sides. Connect them in sequence to obtain four isosceles triangles.

[0012] Furthermore, the two-dimensional 8-1 type derivative crease described in step 3 is obtained by the reduced similar evolution strategy from the two-dimensional basic crease. The two-dimensional 8-1 type derivative crease includes an octagon and eight isosceles triangles with the bases coinciding with the sides of the octagon; the reduced similar evolution strategy is based on the basic circles in the two-dimensional basic crease. Without changing the positions of the centers of the basic circles, synchronously reduce the radii of the basic circles to obtain new mutually separated reduced derivative basic circles. Connect the centers of the reduced derivative basic circles to obtain a regular quadrilateral. The regular quadrilateral intersects with the reduced derivative basic circles to obtain eight intersection points. Connect the eight intersection points in sequence to obtain the octagon of the 8-1 type derivative crease. Make perpendicular bisectors of the four sides of the octagon located inside the reduced derivative basic circles, and take the far intersection points of the perpendicular bisectors and the four reduced derivative basic circles as the vertices of the four isosceles triangles on the sides. Connect them in sequence to obtain four isosceles triangles. With the eight vertices of the octagon as the centers and the side lengths of the four isosceles triangles obtained above as the radii, draw arcs. The intersection points of adjacent arcs are used as the vertices of the remaining four isosceles triangles. Connect them in sequence to obtain the remaining four isosceles triangles of the two-dimensional 8-1 type derivative crease.

[0013] A micro-structured flexible pressure sensor and design method based on crease evolution of the present invention have the following advantages: Systematic design method: The present invention provides a design method for a microstructured flexible pressure sensor based on crease evolution. Through a parametric geometric model and a clear crease evolution strategy, the rational design of microstructural units is achieved, avoiding the randomness and blindness in traditional designs.

[0014] Diverse microstructural units: By combining basic units and derivative units (such as 4-1 type I, 4-1 type II, and 8-1 type), polyhedral microstructures with different contact deformation characteristics can be flexibly designed to meet the performance requirements of sensors in different application scenarios.

[0015] High-performance sensing characteristics: The designed microstructured flexible pressure sensor exhibits high sensitivity and stability under pressure. The resistance change rate varies significantly with the increase in pressure and shows good repeatability and recoverability in cyclic pressure tests.

[0016] Structure optimization and computational support: Through precise geometric parameter calculation formulas, key parameters such as the height and side length of microstructural units can be optimized, thereby achieving precise control over the sensitivity, linearity, and working range of the sensor.

[0017] Innovative crease evolution technology: Introducing the crease evolution strategy in origami technology provides new ideas for microstructural design, not only simplifying the manufacturing process but also enhancing the controllability and consistency of microstructures.

[0018] Broad application prospects: This design method is applicable to fields such as soft robots, smart wearable devices, and medical monitoring, providing reliable technical support for the development of flexible electronic devices.

[0019] In summary, through a systematic design method and innovative crease evolution technology, the present invention solves the randomness problem in the design of microstructured flexible pressure sensors, significantly improving the performance and reliability of the sensors, and having important theoretical value and practical application significance. Brief Description of the Drawings

[0020] Figure 1 It is a schematic structural diagram of the microstructured flexible pressure sensor of the present invention.

[0021] Figure 2 It is a schematic structural diagram of the 4-1 type basic unit of the present invention and the two-dimensional basic crease structure obtained by unfolding it.

[0022] Figure 3 It is a schematic structural diagram of the two-dimensional 4-1 type I derivative crease and the 4-1 type I derivative unit obtained by folding.

[0023] Figure 4 It is a schematic structural diagram of the two-dimensional 4-1 type II derivative crease and the 4-1 type II derivative unit obtained by folding.

[0024] Figure 5 Schematic diagram of the 8-1 type derivative unit structure obtained by two-dimensional 8-1 type derivative creases and folding of the present invention.

[0025] Figure 6 Response and recovery curve of the microstructure flexible pressure sensor of the present invention under different pressures, where (R-R0) / R0 represents the resistance change rate of the sensor.

[0026] Figure 7 Cyclic test curve of the microstructure flexible pressure sensor of the present invention under the action of 4255 Pa pressure, where (R-R0) / R0 represents the resistance change rate of the sensor.

[0027] Marking description in the figure: 1. Upper electrode; 2. Lower electrode; 3. Sensing layer; 31. Flat plate; 32. Microstructure unit; 4. Encapsulation layer. Detailed implementation manners

[0028] In order to better understand the purpose, structure and function of the present invention, the following further describes in detail a microstructure flexible pressure sensor and a design method based on crease evolution of the present invention with reference to the accompanying drawings.

[0029] As Figure 1 shown, a microstructure flexible pressure sensor based on crease evolution of the present invention includes an upper electrode 1 and a lower electrode 2. There is a sensing layer 3 between the upper electrode 1 and the lower electrode 2. The upper and lower ends of the sensing layer 3 are respectively connected to the upper electrode 1 and the lower electrode 22. The sensing layer 3 includes a flat plate 31 and a series of microstructure units 32. Each microstructure unit 32 is connected by the flat plate 31. The upper electrode 1 and the lower electrode 2 are wrapped by polyimide tape as the encapsulation layer 4.

[0030] The upper electrode 1 and the lower electrode 2 can be conductive materials such as copper, gold, and conductive glass.

[0031] The sensing layer 3 can be an ion-conductive hydrogel material mixed with polyvinyl alcohol and anhydrous magnesium chloride, or a PDMS elastomer doped with conductive materials such as graphene or carbon nanotubes.

[0032] The microstructure unit 32 of the sensing layer 3 is a series of polyhedron units with a polygonal bottom surface, isosceles triangle sides, and a single vertex.

[0033] When the bottom surface of the polyhedron unit is a regular quadrilateral and the isosceles triangle on the side is an equilateral triangle, it is defined as a 4-1 type basic unit, where 4 represents the number of vertices of the bottom polygon and 1 represents the number of vertices. [[ID=�8]]

[0034] When the bottom surface of the polyhedron unit is a regular quadrilateral and the ratio of the height of the isosceles triangle on the side to the base is greater than When it is, it is defined as a 4-1 type I derivative unit, where 4 represents the number of vertices of the bottom polygon and 1 represents the number of vertices.

[0035] For the polyhedron unit, when its bottom surface is a regular quadrilateral and the ratio of the height of the isosceles triangle on the side to the base is less than When it is, it is defined as a 4-1 type II derivative unit, where 4 represents the number of vertices of the bottom polygon and 1 represents the number of vertices.

[0036] For the polyhedron unit, when its bottom surface is an octagon and the sides are eight isosceles triangles, it is defined as an 8-1 type derivative unit, where 8 represents the number of vertices of the bottom polygon and 1 represents the number of vertices.

[0037] The 4-1 type I derivative unit, 4-1 type II derivative unit, and 8-1 type derivative unit are obtained from the 4-1 type basic unit based on the derivative design method.

[0038] A derivative design method for the microstructure unit of the sensitive layer based on crease evolution in the present invention is as follows: Step 1: Unfold the 4-1 type basic unit along the edges, reduce it from three dimensions to two dimensions, and obtain a two-dimensional crease pattern with a regular quadrilateral in the center and four isosceles triangles around it, which is defined as the two-dimensional basic crease.

[0039] Step 2: Analyze the geometric characteristics of the two-dimensional basic crease. Define the circumscribed circle of the regular quadrilateral and the circumscribed circles of the four isosceles triangles as the basic circles. The surrounding basic circles are all tangent to the adjacent two basic circles, and the tangent points are the vertices of the central regular quadrilateral.

[0040] Step 3: Based on the similarity evolution strategy, the two-dimensional basic crease evolves to obtain the two-dimensional 4-1 type I derivative crease, the two-dimensional 4-1 type II derivative crease, and the two-dimensional 8-1 type derivative crease.

[0041] The two-dimensional 4-1 type I derivative crease is obtained from the two-dimensional basic crease through the magnification similarity evolution strategy of taking the inner intersection points. The two-dimensional 4-1 type I derivative crease includes a regular quadrilateral and four isosceles triangles with the bases coinciding with the sides of the regular quadrilateral.

[0042] For the magnification similarity evolution strategy of taking the inner intersection points, based on the basic circles in the two-dimensional basic crease, without changing the positions of the centers of the basic circles, synchronously magnify the radii of the basic circles to obtain new magnified derivative basic circles. The adjacent derivative basic circles intersect at two inner and outer intersection points P in and P out , select four inner intersection points P inConnect them in sequence to obtain the bottom quadrilateral of the 4-1 type derivative polyhedron unit. Make perpendicular bisectors on each side of the bottom quadrilateral, and take the far intersection points of the perpendicular bisectors and the four enlarged derivative basic circles as the vertices of the isosceles triangles on the sides. Connect them in sequence to obtain four isosceles triangles.

[0043] The two-dimensional 4-1 type derivative crease is obtained by the enlarged similarity evolution strategy of taking external intersection points from the two-dimensional basic crease. The two-dimensional 4-1 type derivative crease includes a regular quadrilateral and four isosceles triangles with the bases coinciding with the sides of the regular quadrilateral.

[0044] In the enlarged similarity evolution strategy of taking external intersection points, based on the basic circles in the two-dimensional basic crease, without changing the positions of the centers of the basic circles, synchronously enlarge the radii of the basic circles to obtain new enlarged derivative basic circles. Two adjacent derivative basic circles intersect at two internal and external intersection points. P in and P out , select four external intersection points P out Connect them in sequence to obtain the bottom quadrilateral of the 4-1 type derivative polyhedron unit. Make perpendicular bisectors on each side of the bottom quadrilateral, and take the far intersection points of the perpendicular bisectors and the four enlarged derivative basic circles as the vertices of the isosceles triangles on the sides. Connect them in sequence to obtain four isosceles triangles.

[0045] The two-dimensional 8-1 type derivative crease is obtained by the reduced similarity evolution strategy from the two-dimensional basic crease. The two-dimensional 8-1 type derivative crease includes an octagon and eight isosceles triangles with the bases coinciding with the sides of the octagon.

[0046] In the reduced similarity evolution strategy, based on the basic circles in the two-dimensional basic crease, without changing the positions of the centers of the basic circles, synchronously reduce the radii of the basic circles to obtain new non-overlapping reduced derivative basic circles. Connect the centers of the reduced derivative basic circles to obtain a regular quadrilateral. The regular quadrilateral intersects with the reduced derivative basic circles to obtain eight intersection points. Connect the eight intersection points in sequence to obtain the octagon of the 8-1 type derivative crease. Make perpendicular bisectors of the four sides of the octagon that are inside the reduced derivative basic circles, and take the far intersection points of the perpendicular bisectors and the four reduced derivative basic circles as the vertices of the four isosceles triangles on the sides. Connect them in sequence to obtain four isosceles triangles. Taking the eight vertices of the octagon as the centers and the side lengths of the four isosceles triangles obtained above as the radii, draw arcs. The intersection points of adjacent arcs are used as the vertices of the remaining four isosceles triangles. Connect them in sequence to obtain the remaining four isosceles triangles of the two-dimensional 8-1 type derivative crease.

[0047] Step 4: Fold the two-dimensional derivative crease along the sides of the quadrilateral or octagon to obtain the 4-1 type derivative unit, the 4-1 type derivative unit, and the 8-1 type derivative unit. Embodiment

[0048] As shown in Figure 2 , when the 4-1 type basic unit is unfolded along the edge, it is reduced from three dimensions to two dimensions, and a two-dimensional crease pattern with a regular quadrilateral ( □M 1 M 2 M 3 M 4 ) at the center and four isosceles triangles ( △M 1 A 1 M 2 , △M 2 A 2 M 3 , △M 3 A 3 M 4 , △M 4 A 4 M 1 ) around it is obtained. This is defined as the two-dimensional basic crease, and its geometric characteristics are analyzed as follows: 1) Define the circumcircles of the regular quadrilateral and the four isosceles triangles as the basic circles, denoted as O ( O 0 , O 1 , O 2 , O 3 , O 4 , R ). Among them, R is the radius of the basic circle, O 0 , O 1 , O 2 , O 3 , O 4 are the centers of the basic circles. The surrounding basic circles are tangent to the adjacent two basic circles, and the tangent points are the vertices of the central regular quadrilateral M 1 , M 2 ,M 3 , M 4 , the interior angle of a regular quadrilateral is denoted as , the side length is denoted as , and the radius of the base circle R satisfy the relationship: , 2) The height of the 4-1 type basic unit is defined as , the height of the side surface of the 4-1 type basic unit (i.e., the isosceles triangle in the two-dimensional basic crease) is defined as , and the apothem is defined as , and it can be calculated by the following formula:

[0049] Such as Figure 3 shown, based on the base circle in the two-dimensional basic crease, without changing the position of the center of the base circle, the radius of the base circle is synchronously enlarged to obtain a new enlarged derivative base circle O E ( O 0 , O 1 , O 2 , O 3 , O 4 , R E ), define the radius of the new enlarged derivative base circle R E and the radius of the base circle before evolution R The ratio is the similarity ratio w . Adjacent enlarged derivative base circles intersect at two inner and outer intersection points P in and P out , select the four inner intersection points of the enlarged derivative base circle O E and connect them in sequence to obtain the quadrilateral of the 4-1 type derivative crease P in M 1 M 2 M 3 M 4 A 1 A ​​​2 , A 3 , A 4 ), connect them in sequence M 1 A 1 , A 1 M 2 , M 2 A 2 , A 2 M 3 ，M 3 A 3 , A 3 M 4 , M 4 A 4 , A 4 M 1 , four isosceles triangles are obtained. Fold the isosceles triangles along the crease lines to obtain the 4-1 type I derived unit M 1 M 2 M 3 M 4 -A .

[0050] The side length of the bottom regular quadrilateral of the 4-1 type I derived unit , and the similarity ratio w and the side length of the bottom surface of the basic unit are related as follows:

[0051] The height of the side surface of the 4-1 type I derived unit , and the apothem can be calculated by the following formula:

[0052] Combining the above formulas, the height of the 4-1 type I derived unit :

[0053] For example Figure 4As shown, based on the base circle in the two-dimensional base crease, without changing the position of the center of the base circle, the radius of the base circle is simultaneously enlarged to obtain a new enlarged derivative base circle O E ( O 0 , O 1 , O 2 , O 3 , O 4 , R E ), two adjacent enlarged derivative base circles intersect at two inner and outer intersection points P in and P out . Select the four outer intersection points O E of the enlarged derivative base circle P out and connect them in sequence to obtain the quadrilateral of the 4-1 type II derivative crease M 1 M 2 M 3 M 4 . On each side of the quadrilateral, draw the perpendicular bisector and take the far intersection points of the perpendicular bisector and the four enlarged derivative base circles ( A 1 , A 2 , A 3 , A 4 ). Connect them in sequence M 1 A 1 , A 1 M 2 , M 2 A 2 , A 2 M 3 ，M 3 A 3 , A 3 M 4 , M 4A 4 , A 4 M 1 , four isosceles triangles are obtained. Folding the isosceles triangles along the creases gives the 4-1 type II derived unit M 1 M 2 M 3 M 4 -A .

[0054] The side length of the regular quadrilateral at the bottom of the 4-1 type II derived unit , the similarity ratio w and the side length of the bottom of the basic unit are related as follows:

[0055] The height of the side surface of the 4-1 type II derived unit and the apothem can be calculated by the following formula:

[0056] Combining the above formulas, the unit height of the 4-1 type II derived unit can be calculated:

[0057] For example Figure 5 as shown, based on the basic circle in the two-dimensional basic crease, without changing the position of the center of the basic circle, the radius of the basic circle is synchronously reduced to obtain new reduced derived basic circles that are separated from each other O S ( O 0 , O 1 , O 2 , O 3 , O 4 , R S ). Connecting the centers of the reduced basic circles gives a regular quadrilateral O 1 O 2 O 3 O 4 , and the regular quadrilateral and the reduced derived basic circle O S( O 0 , O 1 , O 2 , O 3 , O 4 , R S ) intersect to obtain eight intersection points M 1 , M 2 … M 7 , M 8 . Connect the eight intersection points in sequence to obtain the bottom octagon of the 8 - 1 type derivative crease. Make the perpendicular bisectors of the four sides of the bottom octagon that are inside the reduced basic circle, and take the distant intersection points of the perpendicular bisectors and the four reduced derivative basic circles ( A 1 , A 3 , A 5 , A 7 ), and connect in sequence M 1 A 1 , A 1 M 2 , M 3 A 3 , A 3 M 4 , M 5 A 5 , A 5 M 6 , M 7 A 7 , A 7 M 8 , to obtain the four isosceles triangles on the sides of the 8 - 1 type derivative crease. Denote the length of the base side as . At this time, the four isosceles triangles on the sides and the bottom octagon cannot be folded to form a closed derivative unit. Taking the eight vertices of the bottom octagon as the centers and the side lengths of the four isosceles triangles on the sides (i.e., the line segmentsM 1 A 1 Length) is the radius to draw arcs, the intersection of adjacent arcs ( A 2 , A 4 , A 6 , A 8 ) as the vertices of the remaining isosceles triangles of the 8-1 type derivative crease. Connect them in sequence M 2 A 2 , A 2 M 3 , M 4 A 4 , A 4 M 5 , M 6 A 6 , A 6 M 7 , M 8 A 8 , A 8 M 1 , we get the remaining four isosceles triangles, the length of their bases is recorded as 8-1 derivative units can be obtained by folding M 1 … M 8 - A , the unit height is recorded as .

[0058] 8-1 type derivative unit base length and It can be calculated by the following formula:

[0059] Side height , and the apothem of the long side of the base It can be calculated by the following formula:

[0060]

[0061] Combined with the above formula, the unit height of the 8-1 type derivative unit can be calculated. :

[0062] Fold the two-dimensional derivative crease along the sides of the quadrilateral or octagon to obtain the 4-1 type I derivative unit, 4-1 type II derivative unit, and 8-1 type derivative unit.

[0063] Using polyvinyl alcohol and anhydrous magnesium chloride as the sensitive layer materials, the microstructure flexible pressure sensor with 4-1 basic units, 4-1 type I derivative units, 4-1 type II derivative units, and 8-1 type derivative units finally obtained in this embodiment is as Figure 1 shown. Through the combination of the basic unit and derivative units (such as 4-1 type I, 4-1 type II, and 8-1 type), the present invention can flexibly design polyhedron microstructures with different contact deformation characteristics to meet the requirements of sensor performance in different application scenarios.

[0064] As Figure 6 shown, pressure loads of 700, 1305, 2317, and 3622 Pa are successively applied to the microstructure flexible pressure sensor. As the pressure increases, the resistance change rate of the sensor also increases and recovers with the withdrawal of the pressure load, indicating that the sensing unit is highly sensitive to pressure changes.

[0065] As Figure 7 shown, under the action of a cyclic pressure load of 4255 Pa, the response and recovery of the sensing unit remain stable, indicating that the sensing unit has good pressure response characteristics and repeatability.

[0066] It can be understood that the present invention is described through some embodiments. Those skilled in the art know that without departing from the spirit and scope of the present invention, various changes or equivalent replacements can be made to these features and embodiments. Additionally, under the teaching of the present invention, these features and embodiments can be modified to adapt to specific situations and materials without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application belong to the scope protected by the present invention.

Claims

1. A microstructured flexible pressure sensor based on crease evolution, comprising a sensitive layer (3), wherein the sensitive layer (3) includes a flat plate (31) and a series of microstructural units (32), and each microstructural unit (32) is connected by the flat plate (31), characterized in that, The microstructural unit (32) is a series of polyhedral units with a polygonal bottom surface, isosceles triangular sides, and a single vertex. The polyhedral units are obtained from basic units based on a derivative design method.

2. The microstructural flexible pressure sensor based on crease evolution according to claim 1, characterized in that, The microstructural flexible pressure sensor further includes an upper electrode (1) and a lower electrode (2). The sensitive layer (3) is connected between the upper electrode (1) and the lower electrode (2), and the upper electrode (1) and the lower electrode (2) are wrapped with a packaging layer (4).

3. The microstructural flexible pressure sensor based on crease evolution according to claim 2, characterized in that, The upper electrode (1) and the lower electrode (2) are made of conductive materials.

4. The microstructural flexible pressure sensor based on crease evolution according to claim 1, wherein The sensitive layer (3) is an ion-conductive hydrogel material mixed with polyvinyl alcohol and anhydrous magnesium chloride, or a PDMS elastomer doped with a conductive material.

5. The microstructural flexible pressure sensor based on crease evolution according to claim 1, characterized in that, When the base of the polyhedron unit is a regular quadrilateral and the lateral isosceles triangle is an equilateral triangle, it is defined as a 4-1 type basic unit, where 4 represents the number of vertices of the base polygon and 1 represents the number of vertices; when the base of the polyhedron unit is a regular quadrilateral and the ratio of the height of the lateral isosceles triangle to the base is greater than , it is defined as a 4-1 first type derivative unit, where 4 represents the number of vertices of the base polygon and 1 represents the number of vertices; when the base of the polyhedron unit is a regular quadrilateral and the ratio of the height of the lateral isosceles triangle to the base is less than , it is defined as a 4-1 second type derivative unit, where 4 represents the number of vertices of the base polygon and 1 represents the number of vertices; when the base of the polyhedron unit is an octagon and the lateral sides are eight isosceles triangles, it is defined as an 8-1 type derivative unit, where 8 represents the number of vertices of the base polygon and 1 represents the number of vertices; the 4-1 first type derivative unit, the 4-1 second type derivative unit, and the 8-1 type derivative unit are obtained from the 4-1 type basic unit based on the derivative design method.

6. A method for derivative design of microstructure units of a microstructure flexible pressure sensor based on crease evolution according to any one of claims 1-5, characterized in that, It includes the following steps: Step 1: Unfold the 4-1 type basic unit along the edges, reduce it from three dimensions to two dimensions, and obtain a two-dimensional crease pattern with a regular quadrilateral in the center and four isosceles triangles around it, which is defined as the two-dimensional basic crease. Step 2: Analyze the geometric characteristics of the two-dimensional basic crease. Define the circumcircles of the regular quadrilateral and the four isosceles triangles as basic circles. The surrounding basic circles are all tangent to two adjacent basic circles, and the tangent points are the vertices of the central regular quadrilateral. Step 3: Based on the similar evolution strategy, the two-dimensional basic crease evolves into a two-dimensional 4-1 type I derivative crease, a two-dimensional 4-1 type II derivative crease, and a two-dimensional 8-1 type derivative crease. Step 4: Fold the two-dimensional derivative creases along the sides of the quadrilateral or octagon to obtain a 4-1 type I derivative unit, a 4-1 type II derivative unit, and an 8-1 type derivative unit.

7. The method for derivative design of microstructure units according to claim 6, wherein The two-dimensional 4-1-1 type derivative crease described in step 3 is obtained by the enlarged similarity evolution strategy of taking the inner intersection points from the two-dimensional basic crease. The two-dimensional 4-1-1 type derivative crease includes a regular quadrilateral and four isosceles triangles with the bases coinciding with the sides of the regular quadrilateral. The enlarged similarity evolution strategy of taking the inner intersection points is based on the basic circle in the two-dimensional basic crease. Without changing the position of the center of the basic circle, the radius of the basic circle is synchronously enlarged to obtain a new enlarged derivative basic circle. Adjacent derivative basic circles intersect at two inner and outer intersection points respectively. P in and P out , select four inner intersection points P in and connect them in sequence to obtain the bottom quadrilateral of the 4-1-1 type derivative polyhedron unit. Make perpendicular bisectors on each side of the bottom quadrilateral, and take the distant intersection points of the perpendicular bisectors and the four enlarged derivative basic circles as the vertices of the side isosceles triangles, and connect them in sequence to obtain four isosceles triangles.

8. The derivative design method of the microstructure unit according to claim 6, characterized in that, The two-dimensional 4-1 type II derivative crease described in step 3 is obtained by the enlarged similarity evolution strategy of taking external intersection points from the two-dimensional basic crease. The two-dimensional 4-1 type II derivative crease includes a regular quadrilateral and four isosceles triangles with the bases coinciding with the sides of the regular quadrilateral. The enlarged similarity evolution strategy of taking external intersection points is based on the basic circle in the two-dimensional basic crease. Without changing the position of the center of the basic circle, the radius of the basic circle is synchronously enlarged to obtain a new enlarged derivative basic circle. Two adjacent derivative basic circles intersect at two internal and external intersection points respectively. P in and P out , select four external intersection points P out and connect them in sequence to obtain the bottom quadrilateral of the 4-1 type II derivative polyhedron unit. Make perpendicular bisectors on each side of the bottom quadrilateral, and take the far intersection points of the perpendicular bisectors and the four enlarged derivative basic circles as the vertices of the side isosceles triangles, and connect them in sequence to obtain four isosceles triangles.

9. The derivative design method of the microstructure unit according to claim 6, characterized in that, The two-dimensional 8-1 type derivative crease in Step 3 is obtained from the two-dimensional basic crease through a reduced similarity evolution strategy. The two-dimensional 8-1 type derivative crease includes an octagon and eight isosceles triangles with the bases coinciding with the sides of the octagon. The reduced similarity evolution strategy is based on the basic circles in the two-dimensional basic crease. Without changing the positions of the centers of the basic circles, synchronously reduce the radii of the basic circles to obtain new, mutually separated reduced derivative basic circles. Connect the centers of the reduced derivative basic circles to obtain a regular quadrilateral. The regular quadrilateral intersects with the reduced derivative basic circles to obtain eight intersection points. Connect the eight intersection points in sequence to obtain the octagon of the 8-1 type derivative crease. Draw the perpendicular bisectors of the four sides of the octagon that are inside the reduced derivative basic circles. Take the far intersection points of the perpendicular bisectors and the four reduced derivative basic circles as the vertices of the four side isosceles triangles, and connect them in sequence to obtain four isosceles triangles. With the eight vertices of the octagon as the centers and the side lengths of the four obtained isosceles triangles as the radii, draw arcs. The intersection points of adjacent arcs are used as the vertices of the remaining four isosceles triangles, and connect them in sequence to obtain the remaining four isosceles triangles of the two-dimensional 8-1 type derivative crease.

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