A biomimetic flexible pressure sensor with both ultra-sensitive and wide detection range and its fabrication method

Abstract

This invention discloses a biomimetic flexible pressure sensor with both ultra-high sensitivity and a wide detection range, and its fabrication method, relating to the field of flexible sensor technology. The biomimetic flexible pressure sensor with both ultra-high sensitivity and a wide detection range comprises, from top to bottom: a first protrusion layer and a second protrusion layer, including irregular comb-like protrusion structures; a first arc surface layer and a second arc surface layer, including comb-like gradient arc surface structures, namely elliptical arc surface structures and semi-circular arc surface structures. Compared to existing flexible pressure sensors, the biomimetic flexible pressure sensor with both ultra-high sensitivity and a wide detection range provided by this invention has both ultra-high sensitivity and a wide detection range, while also exhibiting a low detection limit and fast response / recovery time, meeting the needs of industrial robots, medical and health, and wearable device fields for high-performance pressure sensors with both ultra-high sensitivity and a wide detection range.

Description

Technical Field

[0001] This invention relates to the field of flexible sensor technology, and in particular to a biomimetic flexible pressure sensor that combines ultra-sensitivity and a wide detection range, and its fabrication method. Background Technology

[0002] In recent years, with the continuous development of the flexible electronics field, flexible pressure sensors have not only been widely used in wearable devices, but also have potential application value in fields such as intelligent robots, human-computer interaction, and wearable devices. Currently, flexible pressure sensors are developing towards high performance directions such as ultra-sensitivity, wide range, high linearity, and low hysteresis. Among these, ultra-sensitivity and wide detection range are important performance indicators of pressure sensors, which are of great significance for improving the accuracy, adaptability, and safety of sensors. The combination of these two not only expands the application fields of sensors but also improves the overall performance and reliability of the system. Traditional methods often use a single microstructure (micropillar, microcircle, micropyramid, etc.) for sensor design. As pressure increases, the contact area of ​​the sensing material quickly saturates, and the hardening of the single microstructure leads to signal attenuation. Therefore, traditional microstructure designs cannot meet the requirements of simultaneously achieving ultra-sensitivity and a wide detection range.

[0003] To address this issue, researchers have made significant efforts in the microstructure engineering of devices in recent years, proposing several new strategies, primarily involving gradient structures, multilevel structures, and multilayer surface structures. These include large-to-small dome gradient structures, dome-to-gap bilevel structures, multilayer fabric structures, multilayer micropyramid structures, and multilayer sandpaper structures. However, most existing flexible pressure sensors exhibit low sensitivity (<10 kPa) over a wide detection range (>400 kPa). -1 It either exhibits high sensitivity (>100kPa) within a narrower detection range (<100kPa) or high sensitivity within a narrower detection range (>100kPa). -1 Therefore, achieving better synergy between ultra-sensitivity and wide detection range remains a huge challenge. Summary of the Invention

[0004] (a) Technical problems to be solved

[0005] In view of the above-mentioned shortcomings and deficiencies of the prior art, the present invention provides a biomimetic flexible pressure sensor with both ultra-sensitive and wide detection range and its preparation method, which solves the technical problem that existing flexible pressure sensors cannot simultaneously achieve high sensitivity and wide detection range.

[0006] (II) Technical Solution

[0007] A biomimetic flexible pressure sensor with both ultra-sensitive and wide detection range comprises, from top to bottom, a first raised layer, a first arcuate layer, a second arcuate layer, and a second raised layer. The first raised layer is made of flexible material, with an irregular array of raised structures on its bottom surface. The first arcuate layer is made of flexible material, with a semi-cylindrical gradient structure with an arcuate cross-section on its top surface. The second arcuate layer is made of flexible material, with a semi-cylindrical gradient structure with an arcuate cross-section on its bottom surface. The second raised layer is made of flexible material, with an irregular array of raised structures on its top surface. The raised structures of the first raised layer are smaller than those of the second raised layer. The structures of the first and second arcuate layers are identical, with the upper and lower arcuate structures arranged alternately. A first electrode is disposed on the top surface of the first raised layer, and the first electrode is connected to a first wire. A second electrode is disposed on the bottom surface of the second raised layer, and the second electrode is connected to a second wire.

[0008] The lower surface of the first raised layer has irregularly distributed first comb-like protrusions that are in contact with the first arc-shaped layer. The spacing and size of the first comb-like protrusions depend on the mold size. The upper surface of the first raised layer is a plane that is in direct contact with the applied pressure.

[0009] The upper surface of the first arc surface layer has a regularly distributed first comb-like gradient arc surface structure, which is in contact with the first comb-like protrusion structure of the first protrusion layer. The spacing and size of the first comb-like gradient arc surface structure depend on the mold size. The lower surface of the first arc surface layer is a plane, which is in direct contact with the upper surface of the second arc surface layer. The first comb-like gradient arc surface structure includes a first elliptical arc surface structure and a first semi-circular arc surface structure, which are arranged alternately.

[0010] The lower surface of the second arc surface layer has a regularly distributed second comb-like gradient arc surface structure, which is in contact with the second comb-like protrusion structure of the second protrusion layer. The spacing and size of the second comb-like gradient arc surface structure depend on the mold size. The upper surface of the second arc surface layer is a plane and is in direct contact with the lower surface of the first arc surface layer. The second comb-like gradient arc surface structure includes a second elliptical arc surface structure and a second semi-circular arc surface structure, which are arranged alternately.

[0011] The upper surface of the second raised layer has irregularly distributed second comb-like protrusions that are in contact with the second arc-shaped layer. The spacing and size of the second comb-like protrusions depend on the mold size. The lower surface of the second raised layer is a plane that is in direct contact with the bottom surface.

[0012] A biomimetic flexible pressure sensor with both ultra-sensitive and wide detection range, and its fabrication method, is used to fabricate the flexible pressure sensor as described above, comprising:

[0013] The comb-like protrusion structure on the first and second protrusion layers was prepared by a double-molding soft photolithography technique;

[0014] The comb-like gradient arc surface structure on the first and second arc surface layers was prepared by a single-stage molding soft photolithography technique;

[0015] Step 1: Disperse multi-walled carbon nanotubes (MWCNTs) in isopropanol at a ratio of MWCNT:isopropanol = 30:1 and stir magnetically for 2 hours. Then, add polydimethylsiloxane (PDMS) precursor to the MWCNT / isopropanol solution and stir magnetically at 1200 rpm for 12 hours until PDMS is completely dissolved in isopropanol to form a dispersion. Subsequently, heat the mixture in a water bath to 80°C for 1 hour to evaporate the isopropanol, obtaining the PDMS / MWCNT mixture.

[0016] Step 2: Add polydimethylsiloxane PDMS curing agent (curing agent: PDMS = 1:10) and n-hexane (n-hexane to uncured PDMS weight ratio 1:1) to the PDMS / MWCNT mixture in sequence, stir manually for 10 min to obtain a uniformly dispersed PDMS / MWCNT mixture;

[0017] Step 3: Clean the sandpaper with anhydrous ethanol and deionized water in turn, and stick it to the circular glass plate with double-sided tape. Then pour the well mixed epoxy resin (mass ratio 3:1) onto the sandpaper, let it stand at room temperature for 24 hours to cure, and then heat it on a heating table at 90°C for 15 minutes. Peel off the film to obtain the reverse template of the comb protrusion structure. After cooling to room temperature, clean the reverse template of the comb protrusion structure with anhydrous ethanol and deionized water in turn, and dry it for later use.

[0018] Step 4: Clean the 3D-printed comb-like gradient arc surface structure template with anhydrous ethanol and deionized water, then attach it to a circular glass plate with double-sided tape. Pour a well-mixed epoxy resin (mass ratio 3:1) onto the comb-like gradient arc surface structure template, let it stand at room temperature for 24 hours to cure, then place it on a heating table and heat it at 90℃ for 15 minutes. Peel off the film to obtain the comb-like gradient arc surface structure inverse template. After cooling to room temperature, clean the comb-like gradient arc surface structure inverse template with anhydrous ethanol and deionized water, then dry it for later use.

[0019] Step 5: The uniformly dispersed PDMS / MWCNT mixture is introduced into a clean comb-like protrusion structure reverse mold, and the thickness is controlled (~300μm). After heating and curing at 80℃ for 3 hours, the film is peeled off to obtain the first and second protrusion layer conductive elastomers.

[0020] Step 6: The uniformly dispersed PDMS / MWCNT mixture is introduced into a clean comb-like gradient arc surface structure inverse mold, and the thickness is controlled (~300μm). After heating and curing at 80℃ for 3 hours, the film is peeled off to obtain the first arc surface layer and the second arc surface layer conductive elastomer.

[0021] Step 7: Attach the first electrode and the second electrode to the upper and lower sides of the outer surface of the first and second raised layers, respectively. Assemble the four layers in sequence and connect the electrodes to the circuit.

[0022] The four types of thin film samples were stacked in sequence and sealed with silicone rubber. The electrodes used were silver wires with a diameter of 0.1 mm. The silver wires with a diameter of 0.1 mm were attached to the left and right sides of the upper and lower thin films with conductive silver glue. The silver wires with a diameter of 0.1 mm were attached to the two sides of the sample with conductive glue as electrodes.

[0023] (III) Beneficial Effects

[0024] The beneficial effects of this invention are as follows: In the gas sensing structure, this invention draws on the ultra-sensitive sensing mechanism of scorpion combs, namely the stress amplification effect of the protrusion-arc surface combination structure and the multi-gradient sensing wide-range sensing mechanism. Specifically, the comb-like protrusion structure on the surface of the first and second protrusion layers increases the contact area during deformation in the low-pressure range, thereby improving sensitivity. The comb-like gradient arc surface structure on the surface of the first and second arc surface layers enables the sensor to achieve gradient contact deformation of the arc surface structure within a wide pressure detection range, while simultaneously achieving high sensitivity and a wide detection range. In addition, this invention also provides an original multi-layer structure design, with the top and bottom layers being comb-like protrusion structures and the two middle layers being comb-like gradient arc surface structures. The top comb-like protrusion structure is smaller in size, making it easier to deform under low pressure, thus improving sensor sensitivity. The multi-layer structure also makes it easier to evenly distribute high pressure, thereby improving the sensor's wide detection range. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the overall structure of a scorpion comb;

[0026] Figure 2 This is a schematic diagram of the single comb tooth structure of a scorpion's comb.

[0027] Figure 3 This is a schematic diagram of the PEG receptor protrusion structure of a scorpion pectinate.

[0028] Figure 4 This is a schematic diagram of the structure provided by the present invention;

[0029] Figure 5 This is a schematic diagram of the comb-like protrusion structure of the first protrusion layer of the present invention;

[0030] Figure 6 This is a schematic diagram of the gradient arc surface structure of the comb-like first arc surface layer of the present invention;

[0031] Figure 7 This is a schematic diagram of the gradient arc surface structure of the comb-like structure of the second arc surface layer of the present invention;

[0032] Figure 8This is a schematic diagram of the comb-like protrusion structure of the second protrusion layer of the present invention;

[0033] Explanation of reference numerals in the attached figures:

[0034] 100: First raised layer; 101: First comb-like protrusion structure; 102: First wire; 103: First electrode;

[0035] 200: First arc surface layer; 201: First comb-like gradient arc surface structure; 202: First elliptical arc surface structure; 203: First semi-circular arc surface structure;

[0036] 300: Second arc surface layer; 301: Second comb-like gradient arc surface structure; 302: Second elliptical arc surface structure; 303: Second semi-circular arc surface structure;

[0037] 400: Second raised layer; 401: Second comb-like protrusion structure; 402: Second wire; 403: Second electrode; Detailed Implementation

[0038] To better explain and facilitate understanding of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0039] To adapt to complex environments and meet survival needs such as courtship, predation, and evasion of predators, organisms in nature have evolved many unique structures and superior functions, inspiring innovations in human science and technology. The part of a scorpion's pectin that contacts the ground has an arc-shaped structure, densely packed with PEG receptors and protruding structures. At the base of these protruding structures are mechanosensory neurons. During single-comb sensing, as the scorpion walks, its pectin contacts the ground. The deformation of the PEG receptor protrusions on the arc-shaped structure compresses the mechanosensory neurons at the base. A single PEG receptor can sense airflow stimuli (50cm / s to 250cm / s) extruded from a dropper and identify particles as small as 0.5mm in diameter, exhibiting hypersensitive detection capabilities. During multi-comb sensing, the last comb tooth of the pectin contacts the ground first, enabling a wide detection range for mechanical stimuli at an instantaneous depth of 200μm (approximately 5kPa). The protrusions and arc-shaped structures provide hypersensitive detection of mechanical signals. The sequential contact of the last to the top comb teeth with the ground allows for a wide range of detection under high pressure.

[0040] The overall structure of the comb is as follows Figure 1 As shown, it presents an "eight"-shaped distribution, with approximately 25 comb teeth on each side. Based on the order in which the comb teeth sense tactile information from the ground, the comb teeth are distributed in a gradient from low to high.

[0041] The comb-like structure of the comb is as follows Figure 2As shown, the spindle-shaped structure has a large number of PEG receptors densely distributed on the arc-shaped structure in contact with the ground. Each PEG receptor has a raised structure on its top, which facilitates the ultra-sensitive detection of pressure signals.

[0042] The single PEG receptor protrusion structure of the pectin is as follows Figure 3 As shown, at the bottom of the keratinous protrusion structure, there is a narrow slit-like opening at the center of the protrusion structure. The pressure signal first acts on the protrusion structure, which quickly deforms and transmits the mechanical stimulation to the mechanosensory neurons, thus achieving super-sensitive perception of pressure signals.

[0043] The biomimetic flexible pressure sensor, which combines ultra-sensitivity and a wide detection range, is made by imitating the scorpion pectinate, which has excellent pressure sensing capabilities in the biological world. Based on the ultra-sensitivity and wide-range sensing mechanism of the scorpion pectinate's protruding structure and multi-gradient arc surface structure, this invention designs a flexible pressure sensor for the scorpion pectinate.

[0044] like Figure 4 As shown in the embodiment of the present invention, a biomimetic flexible pressure sensor with both ultra-sensitive and wide detection range is proposed. All four layers are composed of polydimethylsiloxane (PDMS) / multi-walled carbon nanotube (MWCNT) conductive elastomers, comprising, from top to bottom: a first protruding layer 100, with a first comb-like protruding structure 101 on the bottom surface of the first protruding layer 100; a first arcuate layer 200, with a first comb-like gradient arcuate structure 201 on the top surface of the first arcuate layer 200, the first comb-like gradient arcuate structure 201 including a first elliptical arcuate structure 202 and a first semi-circular arcuate structure 203; a second arcuate layer 300; and a second arcuate layer... The bottom surface of layer 300 is provided with a second comb-like gradient arc surface structure 301, which includes a second elliptical arc surface structure 302 and a second semi-circular arc surface structure 303; a second protruding layer 400 is provided with a comb-like protruding structure 401 on its top surface; the first arc surface layer 200 has the same structure as the second arc surface layer 300, and the upper and lower arc surface structures are arranged alternately; the top surface of the first protruding layer 100 is provided with a first electrode 103, which is connected to a first wire 102; the bottom surface of the second protruding layer 400 is provided with a second electrode 403, which is connected to a second wire 402.

[0045] In terms of high sensitivity performance, this invention draws on the protrusion and arc surface structure in the ultra-sensitive sensing mechanism of scorpion pectin, namely the stress amplification effect of the protrusion-arc surface combination structure. During the pressure application process, the first pectin protrusion structure 101 and the first pectin arc surface structure 201 of the sensor come into contact in sequence. The stress is concentrated and the deformation is obvious at the top of the protrusion. The contact area between the first protrusion layer 100, the second protrusion layer 400 and the first arc surface layer 200 and the second arc surface layer 300 is increased, resulting in high sensitivity.

[0046] In terms of its performance in the wide pressure detection range, this invention draws on the multi-gradient contact mechanism of scorpion comb teeth. In the large pressure range, the first elliptical arc surface structure 202 in the first comb-like gradient arc surface layer 202 first contacts the first comb-like protrusion structure 101, and then the first comb-like protrusion structure 101 contacts the second semi-circular arc surface structure 203. In addition, the unique four-layer sensing structure design effectively improves the deformation uniformity, avoids the rapid hardening of the microstructure, and improves the wide pressure detection range of the sensor.

[0047] To better understand the above technical solutions, exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that the present invention can be understood more clearly and thoroughly, and that the scope of the present invention can be fully conveyed to those skilled in the art.

[0048] like Figure 5 As shown, the lower surface of the first protrusion layer 100 has irregularly distributed first comb-like protrusion structures 101. The first comb-like protrusion structures 101 are obtained by secondary molding with sandpaper and correspond to the lower first arc surface layer 200. This improves the deformation under pressure, increases the contact area, and improves the sensitivity. A 0.1 mm silver first wire 102 is attached to the first electrode 103 on one side using conductive silver paste. The diameter of the protrusion structure is 5 micrometers.

[0049] like Figure 6 As shown, the upper surface of the first arc layer 200 is distributed with a first comb-like gradient arc structure 201. The first comb-like protrusion structure 201 is obtained by secondary molding using a 3D printing mold. The first comb-like protrusion structure 201 includes a first elliptical arc structure 202 and a first semi-circular arc structure 203, which correspond to the upper first arc protrusion layer 100. The spacing between the first comb-like gradient arc structures 201 is 200 micrometers, and the diameter of the first semi-circular arc structure 203 is 150 micrometers. The first comb-like gradient arc structure 201 improves the deformation effect over a wide pressure range and avoids structural hardening caused by a single structure.

[0050] like Figure 7As shown, the upper surface of the second arc layer 300 is distributed with gradient arc structures 301 that mimic the second comb. The second gradient arc structure 301 is obtained by secondary molding using a 3D printing mold. The second gradient arc structure 301 includes a second elliptical arc structure 302 and a second semi-circular arc structure 303, which correspond to the second protruding layer 400 below. The spacing between the second gradient arc structures 301 is 200 micrometers, and the diameter of the second semi-circular arc structure 303 is 150 micrometers. The vertical and staggered distribution of the second gradient arc structure 301 and the first gradient arc structure 201 improves the deformation effect over a wide pressure range and avoids structural hardening caused by a single structure.

[0051] like Figure 8 As shown, the upper surface of the second raised layer 400 has irregularly distributed first comb-like raised structures 401. These first comb-like raised structures 401 are obtained by secondary molding with sandpaper and correspond to the upper second arc-shaped layer 300. This increases deformation under pressure, expands the contact area, and improves sensitivity. A 0.1mm silver second wire 402 is attached to the second electrode 403 on one side using conductive silver paste. The diameter of the raised structure is 10 micrometers. The sensitivity equation is:

[0052]

[0053] Where I is the current under pressure load; I0 is the current under no pressure load; ΔP is the pressure change;

[0054] On the other hand, the present invention provides a method for fabricating a biomimetic flexible pressure sensor that combines ultra-sensitivity and a wide detection range, comprising:

[0055] S1: Preparation of MWCNT / PDMS conductive elastomer. MWCNT and PDMS were uniformly mixed using the organic solvent isopropanol, followed by the addition of a curing agent and n-hexane, and the mixture was uniformly dispersed using magnetic stirring.

[0056] Further, step S1 includes:

[0057] MWCNT (MWCNT: isopropanol = 30:1) was dispersed in isopropanol and magnetically stirred for 2 hours until MWCNT was uniformly dispersed in isopropanol. PDMS precursor was added to the MWCNT / isopropanol solution and stirred at 1200 rpm for 12 hours until PDMS was completely dissolved in isopropanol to form a dispersion. The mixture was then heated in a water bath to 80°C for 1 hour to evaporate the isopropanol. PDMS curing agent (curing agent: PDMS = 1:10) and n-hexane (n-hexane to uncured PDMS weight ratio 1:1) were added sequentially to the PDMS / MWCNT mixture and manually stirred for 10 minutes to obtain a uniformly dispersed PDMS / MWCNT mixture.

[0058] S2: The first imitation comb gradient arc surface structure 201 and the second imitation comb gradient arc surface structure 301 are replicated onto the PDMS / MWCNT conductive elastomer using a secondary molding soft photolithography technique.

[0059] Further, step S2 includes:

[0060] Molds with a first comb-like gradient arc surface structure 201 and a second comb-like gradient arc surface structure 301 were fabricated using ultra-precision processing equipment such as 3D printing. The molds for the first comb-like gradient arc surface structure 201 and the second comb-like gradient arc surface structure 301 were cleaned sequentially with anhydrous ethanol and deionized water. Epoxy resin material (mass ratio 3:1) was adhered to a circular glass plate with double-sided tape. Then, the uniformly mixed epoxy resin (mass ratio 3:1) was poured onto the molds for the first comb-like gradient arc surface structure 201 and the second comb-like gradient arc surface structure 301. After standing at room temperature for 24 hours to cure, the molds were placed on a heating table and heated at 90°C for 15 minutes. The resulting mold was then peeled off to obtain the first... The first and second imitation comb gradient arc surface structures 201 and 301 are reverse molds. After cooling to room temperature, the first imitation comb gradient arc surface structure 201 and the second imitation comb gradient arc surface structure 301 are washed sequentially with anhydrous ethanol and deionized water, and then dried for later use. The PDMS / MWCNT conductive elastomer prepared in S1 is poured onto the template with the reverse structures of the first imitation comb gradient arc surface structure 201 and the second imitation comb gradient arc surface structure 301. The conductive elastomer film with the first imitation comb gradient arc surface structure 201 and the second imitation comb gradient arc surface structure 301 is prepared by secondary molding, resulting in the first arc surface layer 200 and the second arc surface layer 300.

[0061] S3: The first imitation comb protrusion structure 101 and the second imitation comb protrusion structure 401 of sandpaper are copied onto the PDMS / MWCNT conductive elastomer using a secondary molding soft photolithography technique.

[0062] Select sandpaper of appropriate size for the first imitation comb protrusion structure 101 and the second imitation comb protrusion structure 401, and clean them with anhydrous ethanol and deionized water in sequence. Adhere the sandpaper to a circular glass slide with double-sided tape. Then pour a uniformly mixed epoxy resin (mass ratio 3:1) onto the mold of the first imitation comb protrusion structure 101 and the second imitation comb protrusion structure 401. After standing at room temperature for 24 hours to cure, heat it on a heating table at 90℃ for 15 minutes. Remove the film to obtain the reverse of the first imitation comb protrusion structure 101 and the second imitation comb protrusion structure 401. After the template is cooled to room temperature, the first imitation comb protrusion structure 101 and the second imitation comb protrusion structure 401 reverse template are cleaned sequentially with anhydrous ethanol and deionized water, and then dried for later use. The PDMS / MWCNT conductive elastomer prepared in S1 is poured onto the template with the first imitation comb protrusion structure 101 and the second imitation comb protrusion structure 401 reverse structure. The conductive elastomer film with the first imitation comb protrusion structure 101 and the second imitation comb protrusion structure 401 is prepared by secondary casting to obtain the first protrusion layer 100 and the second protrusion layer 400.

[0063] S4: The first electrode 103 and the second electrode 403 are respectively attached to the upper and lower sides of the outer surface of the first protrusion layer 100 and the second protrusion layer 400. The four layers are assembled in sequence, and the electrodes are connected to the circuit to complete the sensor fabrication.

[0064] The four types of prepared thin film samples were stacked sequentially from bottom to top, with the second raised layer 400, the second arc surface layer 300, the first arc surface layer 200, and the first raised layer 100, and sealed with silicone rubber around the edges. The electrodes used were silver wires with a diameter of 0.1 mm, which were attached to the left and right sides of the upper and lower thin films with conductive silver paste. The silver wires with a diameter of 0.1 mm were attached to the sides of the samples with conductive adhesive as electrodes. The first raised layer 100, the first arc surface layer 200, the second arc surface layer 300, and the second raised layer 400 were encapsulated sequentially from top to bottom using encapsulation PI tape to obtain a biomimetic flexible pressure sensor that combines ultra-sensitivity and a wide detection range.

[0065] In summary, this invention provides a biomimetic flexible pressure sensor with both ultra-high sensitivity and a wide detection range, and a method for fabricating the same. The biomimetic flexible pressure sensor with both ultra-high sensitivity and a wide detection range includes: a first protrusion layer 100, made of flexible material, comprising an irregular first comb-like protrusion structure 101 to improve sensor sensitivity; and a first arcuate layer 200, comprising a first comb-like gradient arcuate structure 201, the first comb-like gradient arcuate structure 201 including a first elliptical arcuate structure 202 and a first semi-circular arcuate structure 203. The second arc surface layer 300 includes a second comb-like gradient arc surface structure 301, which includes a second elliptical arc surface structure 302 and a second semi-circular arc surface structure 303, thereby improving the wide detection range of the sensor; the second protrusion layer 400 is made of flexible material and includes an irregular second comb-like protrusion structure 401; wherein, the protrusion structure of the first protrusion layer 100 is smaller than that of the second protrusion layer 400, and the first arc surface layer 200 and the second arc surface layer 300 have the same structure, with the upper and lower arc surface structures arranged alternately.

[0066] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the claims should be interpreted to include both the preferred embodiments and all changes and modifications falling within the scope of the invention.

[0067] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, then this invention should also include these modifications and variations.

Claims

1. A biomimetic flexible pressure sensor that combines ultra-sensitivity and a wide detection range, characterized in that, From top to bottom, it includes a first raised layer (100), a first arc-shaped layer (200), a second arc-shaped layer (300), and a second raised layer (400). The first raised layer (100) is made of flexible material, and its bottom surface has an irregular array of raised structures. The first arc-shaped layer (200) is made of flexible material, and its top surface has a semi-cylindrical gradient structure with an arc cross-section. The second arc-shaped layer (300) is made of flexible material, and its bottom surface has a semi-cylindrical gradient structure with an arc cross-section. The second raised layer (400) is made of flexible material. The top surface is provided with an irregular array of protrusions; the protrusions of the first protrusion layer (100) are smaller than those of the second protrusion layer (400), the first arc surface layer (200) and the second arc surface layer (300) have the same structure, and the upper and lower arc surface structures are arranged alternately. The top surface of the first protrusion layer (100) is provided with a first electrode (103), and the first electrode (103) is connected to a first wire (102). The bottom surface of the second protrusion layer (400) is provided with a second electrode (403), and the second electrode (403) is connected to a second wire (402).

2. The biomimetic flexible pressure sensor with both ultra-sensitive and wide detection range as described in claim 1, characterized in that, The lower surface of the first raised layer (100) is distributed with irregular first comb-like protrusions (101) and is in contact with the first arc surface layer (200). The spacing and size of the first comb-like protrusions (101) depend on the mold size. The upper surface of the first raised layer (100) is a plane and is in direct contact with the applied pressure.

3. The biomimetic flexible pressure sensor with both ultra-sensitive and wide detection range as described in claim 2, characterized in that, The upper surface of the first arc layer (200) has a regular distribution of the first imitation comb gradient arc structure (201), and it is in contact with the first imitation comb protrusion (101) of the first protrusion layer (100). The spacing and size of the first imitation comb gradient arc structure (201) depend on the mold size. The lower surface of the first arc layer (200) is a plane, which is in direct contact with the upper surface of the second arc layer (300). The first imitation comb gradient arc structure (201) includes a first elliptical arc structure (202) and a first semi-circular arc structure (203). The first elliptical arc structure (202) and the first semi-circular arc structure (203) are arranged alternately.

4. The biomimetic flexible pressure sensor with both ultra-sensitive and wide detection range as described in claim 3, characterized in that, The lower surface of the second arc layer (300) has a regularly distributed second comb-like gradient arc structure (301) that is in contact with the second comb-like protrusion structure of the second protrusion layer (400). The spacing and size of the second comb-like gradient arc structure (301) depend on the mold size. The upper surface of the second arc layer (300) is flat and is in direct contact with the lower surface of the first arc layer (200). The second comb-like gradient arc structure (301) includes a second elliptical arc structure (302) and a second semi-circular arc structure (303). The second elliptical arc structure (302) and the second semi-circular arc structure (303) are arranged alternately.

5. The biomimetic flexible pressure sensor with both ultra-sensitive and wide detection range as described in claim 4, characterized in that, The upper surface of the second raised layer (400) is distributed with irregular second comb-like protrusions (401) and is in contact with the second arc-shaped layer (300). The spacing and size of the second comb-like protrusions (401) depend on the mold size. The lower surface of the second raised layer (400) is a plane and is in direct contact with the bottom surface.

6. A method for fabricating a biomimetic flexible pressure sensor with both ultra-sensitive and wide detection range, used to fabricate the biomimetic flexible pressure sensor with both ultra-sensitive and wide detection range as described in claim 5, characterized in that, Includes the following steps: Step 1: Disperse multi-walled carbon nanotubes (MWCNTs) in isopropanol at a ratio of MWCNT:isopropanol = 30:1 and stir magnetically for 2 hours. Then, add polydimethylsiloxane (PDMS) precursor to the MWCNT / isopropanol solution and stir magnetically at 1200 rpm for 12 hours until PDMS is completely dissolved in isopropanol to form a dispersion. Subsequently, heat the mixture in a water bath to 80°C for 1 hour to evaporate the isopropanol and obtain the PDMS / MWCNT mixture. Step 2: Add polydimethylsiloxane PDMS curing agent and n-hexane to the PDMS / MWCNT mixture in sequence, and stir manually for 10 minutes to obtain a uniformly dispersed PDMS / MWCNT mixture; Step 3: Clean the sandpaper with anhydrous ethanol and deionized water in turn, and stick it to the circular glass plate with double-sided tape. Then pour the well-mixed epoxy resin onto the sandpaper, let it stand at room temperature for 24 hours to cure, and then place it on a heating table and heat it at 90°C for 15 minutes. Peel off the film to obtain the reverse template of the comb protrusion structure. After cooling to room temperature, clean the reverse template of the comb protrusion structure with anhydrous ethanol and deionized water in turn, and dry it for later use. Step 4: Clean the 3D-printed comb-like gradient arc surface structure template with anhydrous ethanol and deionized water, then attach it to a circular glass plate with double-sided tape. Pour the evenly mixed epoxy resin onto the comb-like gradient arc surface structure template, let it stand at room temperature for 24 hours to cure, then place it on a heating table and heat it at 90℃ for 15 minutes. Peel off the film to obtain the reverse template of the comb-like gradient arc surface structure. After cooling to room temperature, clean the reverse template of the comb-like gradient arc surface structure with anhydrous ethanol and deionized water, and dry it for later use. Step 5: The uniformly dispersed PDMS / MWCNT mixture is introduced into a clean comb-like protrusion structure reverse mold, and the thickness is controlled. After heating and curing at 80°C for 3 hours, the film is peeled off to obtain the first protrusion layer (100) and the second protrusion layer (400) conductive elastomer. Step 6: The uniformly dispersed PDMS / MWCNT mixture is introduced into a clean comb-like gradient arc surface structure inverse mold, and the thickness is controlled. After heating and curing at 80°C for 3 hours, the film is peeled off to obtain the first arc surface layer (200) and the second arc surface layer (300) conductive elastomer. Step 7: Attach the first electrode (103) and the second electrode (403) to the upper and lower sides of the outer surfaces of the first raised layer (100) and the second raised layer (400), respectively. Assemble the four layers in sequence and connect the electrodes to the circuit.

7. The method for fabricating a biomimetic flexible pressure sensor with both ultra-sensitivity and a wide detection range according to claim 6, characterized in that: The four types of thin film samples were stacked in sequence and sealed with silicone rubber. The electrodes used were silver wires with a diameter of 0.1 mm. The silver wires with a diameter of 0.1 mm were attached to the left and right sides of the upper and lower thin films with conductive silver glue. The silver wires with a diameter of 0.1 mm were attached to the two sides of the sample with conductive glue as electrodes.

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