Biomimetic petal microstructure-based piezoresistive flexible pressure sensor and preparation method
By designing a biomimetic petal-based microstructure, the balance between high sensitivity and wide range of flexible pressure sensors was solved, achieving continuous response and long-term stability of the pressure sensor over a wide range, and avoiding stress concentration and signal hysteresis.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- ANHUI UNIV
- Filing Date
- 2026-04-27
- Publication Date
- 2026-06-12
AI Technical Summary
Existing flexible pressure sensors struggle to simultaneously achieve high sensitivity and wide measurement range, and it is difficult to achieve a good balance between detecting small signals and applying large pressures. They are prone to signal hysteresis and drift, and their microstructures are susceptible to fatigue damage due to stress concentration.
A piezoresistive flexible pressure sensor based on a biomimetic petal microstructure is adopted. By designing a compressible conductive sensitive layer, including a first conductive base layer, a radially gradient biomimetic petal microstructure, and a second conductive base layer fixed in sequence, the height gradient of the multi-layer annular petal layer is used to achieve step-by-step contact and deformation of external pressure, avoiding the stress concentration and contact saturation problems of traditional microstructures.
It achieves high sensitivity over a wide pressure range, broadens the detection range, and improves the long-term stability and sensitivity of the device, avoiding signal hysteresis and drift.
Smart Images
Figure CN122192570A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of flexible pressure sensor technology, and in particular to a piezoresistive flexible pressure sensor based on a biomimetic petal microstructure and its fabrication method. Background Technology
[0002] Existing flexible pressure sensors struggle to simultaneously achieve high sensitivity and a wide measurement range in their performance design, resulting in limited dynamic response range. Furthermore, achieving a good balance between detecting small signals and applying large pressures is difficult, leading to pronounced nonlinear response characteristics. In addition, due to the viscoelasticity of the sensitive material and structure itself, as well as insufficient changes in the microstructure contact interface, the sensor is prone to signal hysteresis and drift during loading and unloading, thus affecting the accuracy and repeatability of the measurement results.
[0003] To address these issues, existing technologies have incorporated microstructure design to modulate sensing performance. However, traditional, relatively simple microstructures (such as micropillars, microcones, and pyramids) are prone to stress concentration under pressure, causing them to rapidly reach contact saturation and thus limiting the effective detection range of the sensor. Furthermore, under cyclic loading conditions, the microstructure may suffer fatigue damage due to excessive local stress, affecting the long-term stability of the device. Summary of the Invention
[0004] To address the technical problems existing in the background art, this invention proposes a piezoresistive flexible pressure sensor based on a biomimetic petal microstructure and its fabrication method.
[0005] In a first aspect, the present invention proposes a piezoresistive flexible pressure sensor based on a biomimetic petal microstructure, comprising: a compressible conductive sensitive layer, the compressible conductive sensitive layer comprising a first conductive base layer, a radial gradient biomimetic petal microstructure, and a second conductive base layer fixed in sequence, the radial gradient biomimetic petal microstructure comprising multiple annular petal layers arranged coaxially from the inside to the outside, each annular petal layer having the same number of arc-shaped petals and the same height of the arc-shaped petals, the height of the arc-shaped petals in the multiple annular petal layers decreasing in a gradient from the outside to the inside; the arc-shaped petals in each annular petal layer are uniformly arranged circumferentially, and the arc-shaped petals in each annular petal layer are arranged one-to-one in the radial direction.
[0006] Preferably, the first conductive base layer and the radial gradient biomimetic petal microstructure are integrally molded structures.
[0007] Preferably, each arc-shaped petal is radially outward in the direction from the first conductive substrate to the second conductive substrate.
[0008] Preferably, the thickness of each arc-shaped petal gradually decreases in the direction from the first conductive base layer to the second conductive base layer.
[0009] Preferably, the radial gradient biomimetic petal microstructure is formed by multi-walled carbon nanotubes doped with silicone rubber.
[0010] Secondly, the present invention also proposes a method for fabricating a piezoresistive flexible pressure sensor based on a biomimetic petal microstructure, used to fabricate the piezoresistive flexible pressure sensor based on a biomimetic petal microstructure as described in any one of the first aspects, comprising: Using 3D printing technology, the sensitive layer and conductive base layer molds and the second conductive base layer mold are printed according to the preset three-dimensional model of the sensitive layer and conductive base layer and the second conductive base layer model, respectively. Based on a sensitive layer and a conductive base layer mold and a pre-set first conductive composite solution, a first conductive base layer and a radial gradient biomimetic petal microstructure formed on the first conductive base layer are prepared. A second conductive base layer is prepared based on a second conductive base layer mold and a pre-set second conductive composite solution; The second conductive substrate is placed on the side of the radial gradient biomimetic petal microstructure away from the first conductive substrate. Electrode wires are led out from the first and second conductive substrates. The second conductive substrate, the radial gradient biomimetic petal microstructure and the first conductive substrate are bonded and fixed with insulating tape or insulating film to obtain a piezoresistive flexible pressure sensor based on the biomimetic petal microstructure.
[0011] Preferably, the sensitive layer and conductive base layer mold includes a substrate, an annular receiving groove is formed on the top of the substrate, and multiple arc-shaped hole layers are formed on the bottom wall of the annular receiving groove, arranged coaxially from the inside to the outside. Each arc-shaped hole layer includes multiple arc-shaped holes evenly arranged in the circumferential direction. The number of arc-shaped holes in each arc-shaped hole layer is the same, and the multiple arc-shaped holes in each arc-shaped hole layer are arranged one-to-one in the radial direction. The multiple arc-shaped holes in each arc-shaped hole layer have the same depth, and the depth of the arc-shaped holes in the multiple arc-shaped hole layers decreases gradually from the outside to the inside.
[0012] Preferably, each arc-shaped hole is radially outward from top to bottom.
[0013] Preferably, the width of each arc-shaped hole gradually decreases from top to bottom in the radial direction.
[0014] Preferably, the preparation process of the first conductive composite solution includes: first, adding 0.15 g of multi-walled carbon nanotubes to a container, adding a rotor and then pouring in 10 ml of naphtha, and pre-stirring at 900 r / min for 10 min on a magnetic stirrer; then adding 2.5 g of silicone rubber and continuing to stir at 900 r / min for 90 min to obtain the well-stirred first conductive composite solution.
[0015] In this invention, a piezoresistive flexible pressure sensor based on a biomimetic petal microstructure and its fabrication method are proposed. The sensor constructs a compressible conductive sensitive layer comprising a first conductive base layer, a radial gradient biomimetic petal microstructure, and a second conductive base layer, which are fixed in sequence. The compressible conductive sensitive layer achieves step-by-step contact and deformation of external pressure from the outer ring to the inner ring through the height gradient of the multi-ring concentric distribution in the radial gradient biomimetic petal microstructure. This gradually increases the conductive path and achieves continuous change in resistance, thereby effectively avoiding the problem of simultaneous saturation of traditional single-layer or simple gradient microstructures under pressure. Attached Figure Description
[0016] Figure 1 This is a schematic diagram of the structure of a compressible conductive sensitive layer in one embodiment of the present invention.
[0017] Figure 2 This is a schematic diagram of the structure of the first conductive base layer and the compressible conductive sensitive layer in one embodiment of the present invention.
[0018] Figure 3 This is a schematic diagram of the structure of the sensitive layer and the conductive base layer mold in one embodiment of the present invention.
[0019] Figure 4 This is a finite element simulation diagram of a piezoresistive flexible pressure sensor based on a biomimetic petal microstructure under different pressures, as proposed in one embodiment of the present invention.
[0020] Figure 5 This is a schematic diagram showing the sensitivity test results of a piezoresistive flexible pressure sensor based on a biomimetic petal microstructure in one embodiment of the present invention. Detailed Implementation
[0021] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.
[0022] Firstly, referring to Figure 1 and Figure 2 The present invention proposes a piezoresistive flexible pressure sensor based on a biomimetic petal microstructure, comprising: a compressible conductive sensitive layer, the compressible conductive sensitive layer comprising a first conductive base layer 1, a radial gradient biomimetic petal microstructure 2 and a second conductive base layer 3 fixed in sequence, the radial gradient biomimetic petal microstructure 2 comprising multiple annular petal layers arranged coaxially from the inside to the outside, each annular petal layer comprising multiple arc-shaped petals arranged uniformly and at intervals along the circumference, each annular petal layer having the same number of arc-shaped petals, and the multiple arc-shaped petals of the multiple annular petal layers being arranged one-to-one in the radial direction; The multiple arc-shaped petals within each annular petal layer have the same height, and the height of the arc-shaped petals in the multi-layer annular petal layer decreases gradually from the outside to the inside, resulting in a radial gradient distribution in the multi-layer annular petal layer.
[0023] This invention designs a piezoresistive flexible pressure sensor based on a radial gradient biomimetic petal microstructure 2, comprising a first conductive base layer 1, a compressible conductive sensitive layer, and a second conductive base layer 3, which are fixed sequentially. The compressible conductive sensitive layer, through the height gradient of the multi-ring concentrically distributed height distribution in the radial gradient biomimetic petal microstructure 2, achieves gradual contact and deformation of external pressure from the outer ring to the inner ring, gradually increasing the conductive path and realizing continuous resistance variation. This effectively avoids the problem of simultaneous saturation under pressure in traditional single-layer or simple gradient microstructures. Furthermore, the first conductive base layer 1 and the second conductive base layer 3, acting as transition layers, can uniformly distribute external pressure, avoiding stress concentration that could lead to damage to the radial gradient biomimetic petal microstructure 2 under local overload or direct pressure. This facilitates electrode lead-out and avoids localized contact caused by aluminum foil burrs or unevenness when the radial gradient biomimetic petal microstructure 2 is directly bonded to the copper foil electrode.
[0024] In some embodiments, the first conductive base layer 1 and the second conductive base layer 3 are both bonded and fixed to the radial gradient biomimetic petal microstructure 2, and the ratio of the first conductive base layer 1 and the second conductive base layer 3 can be changed according to actual needs.
[0025] In other embodiments, the first conductive base layer 1 and the radial gradient biomimetic petal microstructure 2 are integrally formed to ensure the structural stability of the radial gradient biomimetic petal microstructure 2, facilitate the replacement of the second conductive base layer 3 with different ratios, and reduce costs.
[0026] In some embodiments, a copper foil layer and a silicone rubber layer are sequentially provided on the side of the first conductive base layer 1 and the second conductive base layer 3 away from the compressible conductive sensitive layer, and the copper foil layer is connected to a lead wire.
[0027] Specifically, the copper foil layer is bonded and fixed to the conductive base layer with conductive adhesive, and a silicone rubber layer is used to ensure a tight fit between the copper foil and the first conductive base layer 1, thereby increasing stability.
[0028] In some implementations, each arcuate petal is radially outward in the direction from the first conductive base layer 1 to the second conductive base layer 3 to enhance the structure's ability to deform under pressure.
[0029] To further enhance the structure's ability to deform under pressure, in a further embodiment, the thickness of each arc-shaped petal gradually decreases in the direction from the first conductive base layer 1 to the second conductive base layer 3.
[0030] It should be understood that "multiple" in this embodiment includes two or more.
[0031] In some embodiments, the number of annular petal layers is three, that is, the multiple annular petal layers are referred to as outer ring, middle ring and inner ring from the outside to the inside.
[0032] In some embodiments, the compressible conductive sensitive layer is formed using multi-walled carbon nanotube (MWCNT) doped silicone rubber (SR).
[0033] In a further embodiment, the multi-walled carbon nanotube (MWCNT) doping concentration is 6%.
[0034] In other embodiments, parameters such as the number of rings, number of petals, geometric dimensions and tilt angle of the radial gradient biomimetic petal microstructure 2, as well as the doping ratio of conductive filler, are adjusted to adapt to different pressure detection ranges and sensitivity requirements.
[0035] In this embodiment, the radial gradient biomimetic petal microstructure 2 is formed by the sequential contact and deformation of petals at different heights. On the one hand, this radial gradient biomimetic petal microstructure 2 can gradually disperse external loads, reducing local stress concentration and thus lowering the risk of structural fatigue failure. On the other hand, by delaying the contact saturation process of the overall radial gradient biomimetic petal microstructure 2 through a multi-stage deformation process, the piezoresistive flexible pressure sensor can remain effective over a wider pressure range. This allows the piezoresistive flexible pressure sensor to maintain high sensitivity while further expanding the detection range and improving the long-term operational stability of the device.
[0036] Secondly, the present invention provides a method for fabricating a piezoresistive flexible pressure sensor based on a biomimetic petal microstructure, applicable to the piezoresistive flexible pressure sensor based on a biomimetic petal microstructure as described in any one of the first aspects, comprising: Using 3D printing technology, the sensitive layer and conductive base layer mold 4 and the second conductive base layer mold 3 are printed according to the preset three-dimensional model of the sensitive layer and conductive base layer and the second conductive base layer 3 model, respectively. Based on the sensitive layer, the conductive base layer mold 4, and the preset first conductive composite solution, a first conductive base layer 1 and a compressible conductive sensitive layer formed on the first conductive base layer 1 are prepared. The second conductive base layer 3 is prepared based on the mold of the second conductive base layer 3 and the preset second conductive composite solution; The second conductive base layer 3 is placed on the side of the compressible conductive sensitive layer away from the first conductive base layer 1. Electrode wires are led out from the first conductive base layer 1 and the second conductive base layer 3. The second conductive base layer 3, the radial gradient biomimetic petal microstructure 2 and the first conductive base layer 1 are attached and fixed with insulating tape or insulating film to obtain a piezoresistive flexible pressure sensor based on the radial gradient biomimetic petal microstructure 2.
[0037] This invention employs a combination of 3D printing and molding for fabrication. The process is relatively simple and easy to implement. Furthermore, the geometric parameters of the three-dimensional models of the sensitive layer and the conductive base layer can be adjusted according to actual needs, including the number of petals, thickness, bottom edge size, tilt angle, and the spacing and height difference between adjacent microstructures.
[0038] In some embodiments, the mold preparation process includes: establishing a mold model and using a 3D printer to print a flexible mold using silicone rubber (SR) as the raw material to ensure the geometric accuracy of the microstructure and easy demolding.
[0039] like Figure 3 As shown, in some embodiments, the sensitive layer and conductive base layer mold 4 includes a substrate. An annular receiving groove is formed on the top of the substrate. Multiple arc-shaped hole layers are formed on the bottom wall of the annular receiving groove, arranged coaxially from the inside to the outside. Each arc-shaped hole layer includes multiple arc-shaped holes evenly arranged in the circumferential direction. The number of arc-shaped holes in each arc-shaped hole layer is the same, and the multiple arc-shaped holes in each arc-shaped hole layer are arranged one-to-one in the radial direction. The depth of the multiple arc-shaped holes in each arc-shaped hole layer is the same, and the depth of the arc-shaped holes in the multiple arc-shaped hole layers decreases gradually from the outside to the inside.
[0040] In a further embodiment, each arc-shaped hole is radially outward from top to bottom.
[0041] In a further embodiment, the width of each arc-shaped hole gradually decreases from top to bottom in the radial direction.
[0042] In some embodiments, the first conductive composite solution is poured into the mold 4 of the sensitive layer and the conductive base layer, and left to stand at room temperature overnight to allow the naphtha to fully evaporate before demolding, thereby obtaining the first conductive base layer 1 and the radial gradient biomimetic petal microstructure 2.
[0043] In some embodiments, the preparation process of the first conductive composite solution includes: first, adding 0.15 g of multi-walled carbon nanotubes to a container, adding a rotor and then pouring in 10 ml of naphtha, and pre-stirring at 900 r / min for 10 min on a magnetic stirrer; then adding 2.5 g of silicone rubber and continuing to stir at 900 r / min for about 90 min, i.e., stirring until the first conductive composite solution is in a slightly viscous state, and when a spoonful is scooped out and poured, it is continuous.
[0044] In this embodiment, multi-walled carbon nanotubes (MWCNTs) are first stirred with naphtha to pre-disperse them, and then silicone rubber (SR) is added in a stepwise stirring process with specific speed / time to obtain optimal viscosity and conductivity.
[0045] In some embodiments, the preparation process of the second conductive substrate 3 includes: The second conductive composite solution is poured into the mold of the second conductive base layer 3 and left to dry at room temperature to obtain the second conductive base layer 3.
[0046] In some further embodiments, the second conductive composite solution is the same as the first conductive composite solution.
[0047] In further embodiments, the second conductive composite solution differs from the first conductive composite solution.
[0048] In some embodiments, PI tape is used to bond and fix the second conductive base layer 3, the radial gradient biomimetic petal microstructure 2, and the first conductive base layer 1 to obtain a complete piezoresistive flexible pressure sensor.
[0049] In other embodiments, a PU film is used to encapsulate the second conductive base layer 3, the compressible conductive sensitive layer, and the first conductive base layer 1 to obtain a complete piezoresistive flexible pressure sensor.
[0050] To ensure electrode contact stability and overall flexibility, and to prevent the sensitive layer from detaching or becoming contaminated during repeated use, this embodiment uses a PU film full encapsulation method to achieve reliable signal extraction and mechanical protection, thereby improving the stability and durability of the device.
[0051] The present invention will now be described in conjunction with specific embodiments.
[0052] Example 1 like Figure 1 As shown in the figure, the piezoresistive flexible pressure sensor based on a biomimetic petal microstructure proposed in this embodiment includes: a compressible conductive sensitive layer, which includes a first conductive base layer 1, a radial gradient biomimetic petal microstructure 2, and a second conductive base layer 3 fixed in sequence. The first conductive base layer 1 and the radial gradient biomimetic petal microstructure 2 are integrally formed structures. The radial gradient biomimetic petal microstructure 2 includes three annular petal layers arranged coaxially from the inside to the outside, namely an outer ring, a middle ring, and an inner ring. Each annular petal layer includes multiple arc-shaped petals arranged uniformly and at intervals along the circumference. The number of arc-shaped petals in each annular petal layer is the same, and the multiple arc-shaped petals in the three annular petal layers are arranged one-to-one in the radial direction. The multiple arc-shaped petals in each annular petal layer have the same height, and the height of the arc-shaped petals in the multiple annular petal layers gradually decreases from the outside to the inside, so that the multiple annular petal layers form a radial gradient distribution. Each arc-shaped petal is radially outward in the direction from the first conductive base layer 1 to the second conductive base layer 3, and the thickness of each arc-shaped petal gradually decreases in the direction from the first conductive base layer 1 to the second conductive base layer 3. The first conductive base layer 1 and the radial gradient biomimetic petal microstructure 2 are formed by multi-walled carbon nanotubes doped with silicone rubber.
[0053] The sensitivity of the piezoresistive flexible pressure sensor in Example 1 was tested, and the test results are as follows: Figure 5 As shown. From Figure 5It can be seen that the piezoresistive flexible pressure sensor maintains an effective response in the range of 0–80 kPa; in the low-pressure range (0–approximately 10 kPa), the sensitivity reaches 15.67% / kPa (R). 2 =0.8476), with a sensitivity of 1.01% / kPa in the medium pressure range (approximately 10–40 kPa). 2 =0.9416), and remains at 0.15% / kPa (R) in the high-pressure section (40–80 kPa). 2 With a measurable sensitivity of 0.9297, it achieves a continuous response from small pressures to large pressures, balancing sensitivity and detection range.
[0054] Finite element simulation was performed on the piezoresistive flexible pressure sensor of Example 1, and the simulation results are shown in Figure 4. Figure 4 It can be seen that when pressure is applied, the upper layer (the area corresponding to the outer ring) first shows a higher pressure distribution, and then the pressure is gradually transmitted to the lower layer, showing a gradient change trend from the outside to the inside. This is basically consistent with the piecewise sensitivity curve measured in the experiment, and also verifies the hierarchical contact mechanism of the radial gradient biomimetic petal microstructure.
[0055] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.
Claims
1. A piezoresistive flexible pressure sensor based on a biomimetic petal microstructure, characterized in that, include: The compressible conductive sensitive layer includes a first conductive base layer, a radial gradient biomimetic petal microstructure, and a second conductive base layer, which are fixed in sequence. The radial gradient biomimetic petal microstructure includes multiple annular petal layers arranged coaxially from the inside to the outside. The number of arc-shaped petals in each annular petal layer is the same, and the height of the arc-shaped petals is the same. The height of the arc-shaped petals in the multiple annular petal layers decreases gradually from the outside to the inside. The arc-shaped petals in each annular petal layer are uniformly arranged circumferentially, and the arc-shaped petals in each annular petal layer are arranged one-to-one in the radial direction.
2. The piezoresistive flexible pressure sensor based on a biomimetic petal microstructure according to claim 1, characterized in that, The first conductive base layer and the radial gradient biomimetic petal microstructure are integrally molded structures.
3. The piezoresistive flexible pressure sensor based on a biomimetic petal microstructure according to claim 2, characterized in that, Each arc-shaped petal tilts radially outward in the direction from the first conductive substrate to the second conductive substrate.
4. The piezoresistive flexible pressure sensor based on a biomimetic petal microstructure according to claim 3, characterized in that, The thickness of each arc-shaped petal gradually decreases from the first conductive base layer to the second conductive base layer.
5. The piezoresistive flexible pressure sensor based on a biomimetic petal microstructure according to claim 1, characterized in that, The radial gradient biomimetic petal microstructure is formed by multi-walled carbon nanotubes doped with silicone rubber.
6. A method for fabricating a piezoresistive flexible pressure sensor based on a biomimetic petal microstructure, used to fabricate the piezoresistive flexible pressure sensor based on a biomimetic petal microstructure as described in any one of claims 2-5, characterized in that, include: Using 3D printing technology, the sensitive layer and conductive base layer molds and the second conductive base layer mold are printed according to the preset three-dimensional model of the sensitive layer and conductive base layer and the second conductive base layer model, respectively. Based on a sensitive layer and a conductive base layer mold and a pre-set first conductive composite solution, a first conductive base layer and a radial gradient biomimetic petal microstructure formed on the first conductive base layer are prepared. A second conductive base layer is prepared based on a second conductive base layer mold and a pre-set second conductive composite solution; The second conductive substrate is placed on the side of the radial gradient biomimetic petal microstructure away from the first conductive substrate. Electrode wires are led out from the first and second conductive substrates. The second conductive substrate, the radial gradient biomimetic petal microstructure and the first conductive substrate are bonded and fixed with insulating tape or insulating film to obtain a piezoresistive flexible pressure sensor based on the biomimetic petal microstructure.
7. The method for fabricating a piezoresistive flexible pressure sensor based on a biomimetic petal microstructure according to claim 6, characterized in that, The sensitive layer and conductive base layer mold includes a substrate. An annular receiving groove is formed on the top of the substrate. Multiple arc-shaped hole layers are formed on the bottom wall of the annular receiving groove, arranged coaxially from the inside to the outside. Each arc-shaped hole layer includes multiple arc-shaped holes evenly arranged in the circumferential direction. The number of arc-shaped holes in each arc-shaped hole layer is the same, and the multiple arc-shaped holes in each arc-shaped hole layer are arranged one-to-one in the radial direction. The multiple arc-shaped holes in each arc-shaped hole layer have the same depth, and the depth of the arc-shaped holes in the multiple arc-shaped hole layers decreases gradually from the outside to the inside.
8. The method for fabricating a piezoresistive flexible pressure sensor based on a biomimetic petal microstructure according to claim 7, characterized in that, Each arc-shaped hole is radially outward from top to bottom.
9. The method for fabricating a piezoresistive flexible pressure sensor based on a biomimetic petal microstructure according to claim 7, characterized in that, The width of each arc-shaped hole gradually decreases from top to bottom in the radial direction.
10. The method for fabricating a piezoresistive flexible pressure sensor based on a biomimetic petal microstructure according to claim 6, characterized in that, The preparation process of the first conductive composite solution includes: first, adding 0.15 g of multi-walled carbon nanotubes to a container, adding a rotor and then pouring in 10 ml of naphtha, and pre-stirring at 900 r / min for 10 min on a magnetic stirrer; then adding 2.5 g of silicone rubber and continuing to stir at 900 r / min for 90 min to obtain the stirred first conductive composite solution.