Bionic flexible touch sensor and preparation method and application thereof

Abstract

The invention relates to the technical field of sensors, in particular to a bionic flexible tactile sensor and a preparation method and application thereof, and the bionic flexible tactile sensor comprises a substrate layer, an electrode layer, a PZT (at) PDMS piezoelectric sensing sensitive layer, a flexible deformation layer and a rigid pressure amplification layer which are stacked in sequence; the PZT (at) PDMS piezoelectric sensing sensitive layer comprises a plurality of strip-shaped PZT (at) PDMS piezoelectric sensing sensitive units which are arranged at intervals; the flexible deformation layer is partially embedded in a gap between the strip-shaped PZT (at) PDMS piezoelectric sensing and sensing units; the bionic flexible tactile sensor is provided with a plurality of crack units from the rigid pressure amplification layer to the PZT (at) PDMS piezoelectric sensing sensitive layer. According to the invention, a strain amplification structure in a scorpion slit receptor in nature is used for reference in structure, exoskeleton epidermis parts at two sides of a scorpion slit are rigid, and subcutaneous tissue parts and crack end parts are flexible, so that a strain concentration effect at a soft material can be realized by utilizing a hard-soft-hard structure of the slit of the biological body surface sensor; and the sensitivity of tactile signal detection is improved.

Description

Technical Field

[0001] The present invention relates to the field of sensor technology, and in particular to a bionic flexible tactile sensor and a preparation method and application thereof. Background Art

[0002] Flexible tactile sensors have attracted widespread attention due to their thinness, extensibility, and tactile perception similar to human skin. At present, most flexible tactile sensors use different transduction mechanisms to convert external stimuli into electrical signals by imitating the working mechanism of biological skin or surface receptors. These sensors have played an important role in various emerging fields in recent years, such as smart health equipment, advanced human-computer interfaces and human-computer interaction technologies, showing great application potential in many fields. These include but are not limited to flexible wearable electronic devices, flexible health monitoring devices, smart prostheses, and smart robotics technology. In particular, flexible tactile sensors play a vital role in promoting human physiological health monitoring and human-computer interaction.

[0003] Currently, for flexible tactile sensors, innovation in sensor transducer materials and introduction of new mechanical structure designs have been proven to be effective ways to improve their sensitivity and increase their ductility.

[0004] At present, flexible tactile sensors based on the piezoelectric principle are mainly divided into inorganic piezoelectric materials and organic piezoelectric materials in terms of materials. Inorganic piezoelectric materials usually have a large piezoelectric coefficient (such as the common lead zirconate titanate ceramic, i.e., piezoelectric ceramic transducer, PZT), but the material itself is a brittle material, cannot be bent, and has a very small elastic elongation. The strain at which it is damaged is usually less than 2%. Based on polymer materials with piezoelectric effect such as polyvinylidenedifluoride (PVDF), it is an intrinsically ductile material that allows large strains without failure, but its piezoelectric coefficient is small.

[0005] Therefore, the prior art still needs to be improved and developed. Summary of the invention

[0006] In view of the above-mentioned deficiencies in the prior art, an object of the present invention is to provide a bionic flexible tactile sensor and a preparation method and application thereof, aiming to solve the problems that traditional flexible tactile sensors are not soft enough and have a small piezoelectric coefficient.

[0007] The technical solution of the present invention is as follows:

[0008] A bionic flexible tactile sensor, comprising a substrate layer, an electrode layer, a PZT@PDMS piezoelectric sensing layer, a flexible deformation layer and a rigid pressure amplification layer stacked in sequence;

[0009] The PZT@PDMS piezoelectric sensing sensitive layer includes a plurality of strip-shaped PZT@PDMS piezoelectric sensing sensitive units arranged at intervals; the flexible deformation layer is partially embedded in the intervals between the strip-shaped PZT@PDMS piezoelectric sensing sensitive units; the bionic flexible tactile sensor is provided with a plurality of crack units from the rigid pressure amplification layer to the PZT@PDMS piezoelectric sensing sensitive layer.

[0010] The bionic flexible tactile sensor, wherein the material of the base layer is selected from one of polyimide, polyethylene terephthalate, and polyetheretherketone; and / or the material of the electrode layer is selected from one of Au, Ag, Cu, Cr, graphite, copper-tungsten alloy, and silver-tungsten alloy.

[0011] In the bionic flexible tactile sensor, the material of the flexible deformation layer is selected from one of PDMS, silica gel, and ecoflex; the material of the rigid pressure amplification layer is selected from one of polymethyl methacrylate and glass.

[0012] The bionic flexible tactile sensor, wherein the interval between two adjacent strip-shaped PZT@PDMS piezoelectric sensing sensitive units is 0.4mm-0.6mm.

[0013] The bionic flexible tactile sensor, wherein the crack width of the crack unit is 500 μm-1000 μm; and the spacing between two crack units is 1 mm-2 mm.

[0014] The bionic flexible tactile sensor, wherein the thickness of the base layer is 15μm-25μm; the thickness of the electrode layer is 150nm-250nm; the thickness of the PZT@PDMS piezoelectric sensing sensitive layer is 250μm-350μm; the thickness of the flexible deformation layer is 400μm-500μm; the thickness of the rigid pressure amplification layer is 400μm-500μm.

[0015] A method for preparing a bionic flexible tactile sensor comprises the following steps:

[0016] forming a base layer on a substrate;

[0017] forming an electrode layer on the base layer;

[0018] The PZT nanoparticles are mixed with the PDMS precursor solution, and the PDMS curing agent is added to obtain the PZT@PDMS piezoelectric sensitive material colloid;

[0019] Using a mask plate, the PZT@PDMS piezoelectric sensitive material colloid is coated on the surface of the electrode layer to obtain a PZT@PDMS piezoelectric sensitive layer;

[0020] A flexible deformation layer and a rigid pressure amplification layer are sequentially formed by coating on the PZT@PDMS piezoelectric sensing sensitive layer, and a crack unit is formed by etching, thereby obtaining a bionic flexible tactile sensor.

[0021] The method for preparing the bionic flexible tactile sensor, wherein the particle size of the PZT nanoparticles is 600nm-950nm.

[0022] The method for preparing the bionic flexible tactile sensor, wherein, in the PZT@PDMS piezoelectric sensitive material colloid, the mass ratio of PZT nanoparticles to PDMS is 2:(0.25-0.5).

[0023] Application of a bionic flexible tactile sensor in a manipulator.

[0024] Beneficial effects: The present invention provides a bionic flexible tactile sensor and a preparation method and application thereof. The bionic flexible tactile sensor comprises a substrate layer, an electrode layer, a PZT@PDMS piezoelectric sensing sensitive layer, a flexible deformation layer and a rigid pressure amplification layer stacked in sequence; the PZT@PDMS piezoelectric sensing sensitive layer comprises a plurality of strip-shaped PZT@PDMS piezoelectric sensing sensitive units arranged at intervals; the flexible deformation layer is partially embedded in the intervals between the strip-shaped PZT@PDMS piezoelectric sensing sensitive units; the bionic flexible tactile sensor is provided with a plurality of crack units from the rigid pressure amplification layer to the PZT@PDMS piezoelectric sensing sensitive layer. The bionic flexible tactile sensor of the present invention draws on the strain amplification structure of the scorpion slit receptor in nature in terms of structure. The exoskeleton epidermis on both sides of the scorpion slit is rigid, while the subcutaneous tissue part and the ends of the slit are flexible. By utilizing the "hard-soft-hard" structure of the biological surface sensor slit, the strain concentration effect at the soft material can be achieved, thereby improving the sensitivity of tactile signal detection. Therefore, the present invention utilizes a substrate layer, an electrode layer, a PZT@PDMS piezoelectric sensing sensitive layer, a flexible deformation layer and a rigid pressure amplification layer stacked in sequence to form a "hard-soft-hard" structure, and a number of crack units are provided from the rigid pressure amplification layer to the PZT@PDMS piezoelectric sensing sensitive layer to obtain a scorpion-like slit receptor, which has good uniformity and passive driving mode, thereby realizing high-resolution tactile sensing. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic cross-sectional view of the overall structure of a bionic flexible tactile sensor of the present invention;

[0026] Figure 2 This is a schematic diagram of the explosion structure of a bionic flexible tactile sensor of the present invention;

[0027] Figure 3is a schematic diagram of the structure of the electrode layer;

[0028] Figure 4 Schematic diagram of the exploded structure of the bionic flexible tactile sensing system integrated with 4×4 bionic flexible tactile sensors;

[0029] Figure 5 This is a schematic diagram of the preparation process of a bionic flexible tactile sensor of the present invention;

[0030] Figure 6 The voltage response data diagram of the bionic flexible tactile sensor prepared in Example 1 in three states;

[0031] Explanation of the reference numerals: base layer 10 , electrode layer 20 , first electrode layer 21 , second electrode layer 22 , PZT@PDMS piezoelectric sensing sensitive layer 30 , strip-shaped PZT@PDMS piezoelectric sensing sensitive unit 31 , flexible deformation layer 40 , rigid pressure amplification layer 50 , crack unit 60 . DETAILED DESCRIPTION

[0032] The present invention provides a bionic flexible tactile sensor and a preparation method and application thereof. To make the purpose, technical solution and effect of the present invention clearer and more specific, the present invention is further described in detail below. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0033] It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as generally understood by those skilled in the art in the art to which the present invention belongs. It should also be understood that terms such as those defined in general dictionaries should be understood to have meanings consistent with the meanings in the context of the prior art, and will not be interpreted with idealized or overly formal meanings unless specifically defined as herein.

[0034] In addition to the field of smart medical care, in the areas of human-machine interaction and human-machine integration, especially in the areas of smart prostheses, robots, and robotic arms, with the continuous advancement of science and technology, robotic arms are gradually becoming intelligent in many fields such as industry, agriculture, and medical care. In the fields of bionic prostheses, fruit and vegetable picking and sorting, cargo handling, and life care robots, intelligent robotic arms have now become a cutting-edge technical issue. In order to make intelligent robotic arms more flexible in interacting with unstructured environments and sensitive to tiny signals, a large number of tactile sensors are usually required to collect information such as the clamping force during the grasping process. Among them, the tactile sensors integrated in the robot are crucial, and it is urgent to solve the design and manufacture of such tactile sensors and realize high-sensitivity detection of tactile signals.

[0035] In terms of the design of new mechanical structures of sensors, common practices include increasing the contact area, increasing the roughness of the contact surface, increasing the specific surface area of ​​the contact surface, etc., such as the contact surface of the common micro-pyramid boss. Another idea is to concentrate the stress / strain of the area where the transducer material is arranged through the structure / material design of the substrate.

[0036] Based on this, Figure 1 and Figure 2 As shown, the present invention provides a bionic flexible tactile sensor, comprising a base layer 10, an electrode layer 20, a PZT@PDMS piezoelectric sensing sensitive layer 30, a flexible deformation layer 40 and a rigid pressure amplification layer 50 which are stacked in sequence;

[0037] The PZT@PDMS piezoelectric sensing sensitive layer 30 includes a plurality of strip-shaped PZT@PDMS piezoelectric sensing sensitive units 31 arranged at intervals; the flexible deformation layer 40 is partially embedded in the intervals between the strip-shaped PZT@PDMS piezoelectric sensing sensitive units 31; the bionic flexible tactile sensor is provided with a plurality of crack units 60 from the rigid pressure amplification layer 50 to the PZT@PDMS piezoelectric sensing sensitive layer 30.

[0038] In this embodiment, PZT (lead zirconate titanate ceramic, i.e., piezoelectric ceramic transducer) nanoparticles are mixed with a PDMS (polydimethylsiloxane) precursor solution to form a flexible piezoelectric material, i.e., the PZT@PDMS piezoelectric sensing sensitive layer 30, and then through a "bottom-up" stacking manufacturing step, the base layer 10, the electrode layer 20, the PZT@PDMS piezoelectric sensing sensitive layer 30, the flexible deformation layer 40 and the rigid pressure amplification layer 50 are formed into a "hard-soft-hard" structure, and a plurality of crack units are provided from the rigid pressure amplification layer 50 to the PZT@PDMS piezoelectric sensing sensitive layer 30 to obtain a scorpion-like slit sensor, which uses the PZT@PDMS piezoelectric sensing sensitive layer 30 as a transducer material and uses the base layer 10 and the rigid pressure amplification layer 50 to provide rigidity, so as to realize the strain concentration effect of the bionic flexible tactile sensor at the soft material and improve the sensitivity of tactile signal detection.

[0039] Specifically, the present invention disperses lead zirconate titanate ceramic PZT nanoparticles in flexible soft material silica gel to form a flexible piezoelectric material; and on the flexible piezoelectric material, a strain sensor structure with a crack morphology at the joint of a scorpion's foot is imitated, and through the design of a bionic flexible tactile sensor structure, the flexible piezoelectric material is arranged in a strain sensitive area as a PZT@PDMS piezoelectric sensing sensitive layer; the bionic flexible tactile sensor utilizes the PZT@PDMS piezoelectric sensing sensitive layer to generate an electric charge or voltage when subjected to mechanical stress, and this characteristic enables the piezoelectric sensor to work without an external power supply, and can directly convert mechanical energy into electrical energy. At the same time, combined with the scorpion-like slit sensor structure, the bionic flexible tactile sensor can achieve a high sensitivity and self-powered effect based on the piezoelectric effect; and the bionic flexible tactile sensor of the structure has high sensitivity, high resolution, fast response time, high flexibility and stable electrical properties, which solves the problems of insufficient softness and small piezoelectric coefficient of traditional piezoelectric film sensors; at the same time, the preparation process of the bionic flexible tactile sensor of the structure is simple and can be industrialized.

[0040] Furthermore, when the bionic flexible tactile sensor is stimulated by a normal force, the external stress is first transmitted to the rigid pressure amplification layer with a crack structure. When the two adjacent rigid pressure amplification layers separated by the crack squeeze each other, the strain is amplified in the vertical direction and transmitted to the lower PZT@PDMS piezoelectric sensing sensitive layer. In this process, the strain is amplified, and the voltage in the PZT@PDMS piezoelectric sensing sensitive area is transmitted through the electrode at its bottom as the output tactile sensor output.

[0041] In some embodiments, the material of the base layer 10 is selected from, but not limited to, one of polyimide (PI), polyethylene terephthalate, and polyetheretherketone; and / or, the material of the electrode layer 20 is selected from, but not limited to, one of Au, Ag, Cu, Cr, graphite, copper-tungsten alloy, and silver-tungsten alloy. The base layer 10 formed by the above materials has good flexibility, and its hardness is higher than that of the PZT@PDMS piezoelectric sensing sensitive layer 30, and can better form a "hard-soft-hard" structure; when the material of the electrode layer is the above materials, it has good conductivity, good flexibility, and is not easy to break.

[0042] In some embodiments, Figure 3As shown, the electrode layer 20 also includes a first electrode layer 21 and a second electrode layer 22; the first electrode layer 21 and the second electrode layer 22 are symmetrically arranged, and the first electrode layer 21 and the second electrode layer 22 are arranged at intervals, and the two do not contact each other. The electrode layer 20 formed by this structure can make the bionic flexible tactile sensor have good flexibility, and the electrode layer 20 maintains good conductivity as the sensor changes in shape such as bending and folding.

[0043] Specifically, the first electrode layer 21 and the second electrode layer 22 are both composed of a main electrode and a plurality of branch electrodes extending from the main electrode to one side, the plurality of branch electrodes are arranged at intervals, and the first electrode layer 21 and the second electrode layer 22 are coupled to each other through the branch electrodes but do not contact each other to form the electrode layer 20; of course, the electrode layer 20 may also include other patterns that can achieve the same function.

[0044] In some embodiments, the material of the flexible deformation layer is selected from but not limited to one of PDMS, silicone, and ecoflex; the material of the rigid pressure amplification layer is selected from but not limited to one of polymethyl methacrylate (PMMA) and glass. Using PDMS, silicone, and ecoflex as the material of the flexible deformation layer can make the bionic flexible tactile sensor have better flexibility, and combined with the rigidity of the rigid pressure amplification layer, the sensor can form a "hard-soft-hard" structure, which can realize the strain concentration application at the soft material and improve the sensitivity of tactile signal detection; on the other hand, covering the PZT@PDMS piezoelectric sensing sensitive layer 30 with a flexible deformation layer can make the flexible deformation layer serve as the main strain bearing area, and can also serve as an encapsulation layer to protect the PZT@PDMS piezoelectric sensing sensitive layer.

[0045] In a preferred embodiment, the material of the flexible deformation layer is PDMS; the material of the rigid pressure amplification layer is polymethyl methacrylate (PMMA).

[0046] In some embodiments, the interval between two adjacent strip-shaped PZT@PDMS piezoelectric sensing sensitive units is 0.4mm-0.6mm; controlling the interval between two adjacent strip-shaped PZT@PDMS piezoelectric sensing sensitive units to be between 0.4mm-0.6mm can enable the bionic flexible tactile sensor to better utilize the crack unit 60 to achieve strain concentration at the soft material, thereby improving the sensitivity of tactile signal detection. For example, the interval between two adjacent strip-shaped PZT@PDMS piezoelectric sensing sensitive units can be, but is not limited to, 0.4mm, 0.45mm, 0.5mm, 0.55mm, 0.6mm.

[0047] In a preferred embodiment, the interval between two adjacent strip-shaped PZT@PDMS piezoelectric sensing sensitive units is 0.5 mm. When the interval between two adjacent strip-shaped PZT@PDMS piezoelectric sensing sensitive units is 0.5 mm, the sensitivity of the tactile signal detection of the bionic flexible tactile sensor can reach an optimal state.

[0048] In some embodiments, the crack width of the crack unit is 500μm-1000μm; the spacing between the two crack units is 1mm-2mm. The strain sensor structure with crack morphology at the joint of the scorpion's foot formed by the crack width and the spacing of the crack units can better generate strain concentration at the soft material when subjected to mechanical force to generate charge or voltage, so that the sensor has high sensitivity and high resolution. Fast response time, high flexibility and stable electrical performance advantages. For example, the crack width of the crack unit can be but not limited to 500μm, 550μm, 600μm, 650μm, 700μm, 750μm, 800μm, 850μm, 900μm, 950μm, 1000μm; the spacing between the two crack units can be but not limited to 1mm, 1.2mm, 1.4mm, 1.6mm, 1.7mm, 1.9mm, 2mm.

[0049] In a preferred embodiment, the crack width of the crack unit is 500μm; the spacing between the two crack units is 1mm; when the crack width of the crack unit is 500μm; the spacing between the two crack units is 1mm, the bionic flexible tactile sensor with a "hard-soft-hard" structure has a better strain concentration effect at the soft material, which can make the sensitivity of the tactile signal detection of the bionic flexible tactile sensor reach the optimal level. In addition, compared with existing tactile sensors of other structures, the bionic flexible tactile sensor adopts a bionic slit structure, which can amplify the mechanical deformation ability of external input, thereby improving the sensitivity of the sensor to strain.

[0050] In some embodiments, the thickness of the substrate layer is 15 μm-25 μm; the thickness of the electrode layer is 150 nm-250 nm; the thickness of the PZT@PDMS piezoelectric sensing layer is 250 μm-350 μm; the thickness of the flexible deformation layer is 400 μm-500 μm; the thickness of the rigid pressure amplification layer is 400 μm-500 μm. By controlling the thickness of each layer of the bionic flexible tactile sensor within the above range, a bionic flexible tactile sensor with a thinner thickness can be obtained, so that it can be better applied to the control of the gripping force of the manipulator.

[0051] In a preferred embodiment, the thickness of the base layer is 20 μm; the thickness of the electrode layer is 200 nm; the thickness of the PZT@PDMS piezoelectric sensing sensitive layer is 300 μm; the thickness of the flexible deformation layer is 500 μm; and the thickness of the rigid pressure amplification layer is 500 μm.

[0052] In some embodiments, the planar dimensions of the bionic flexible tactile sensor may be, but are not limited to, 10 mm in width, 10 mm-20 mm in length, and 1.1 mm-1.2 mm in thickness; the sensor with this dimension has good sensitivity.

[0053] In some embodiments, the width of the strip-shaped PZT@PDMS piezoelectric sensing sensitive unit 31 is 1 mm-1.2 mm; the length of the strip-shaped PZT@PDMS piezoelectric sensing sensitive unit 31 is 8 mm-15 mm.

[0054] In a preferred embodiment, the width of the strip-shaped PZT@PDMS piezoelectric sensing sensitive unit 31 is 1 mm; the length of the strip-shaped PZT@PDMS piezoelectric sensing sensitive unit 31 is 10 mm.

[0055] In some embodiments, the bionic flexible tactile sensors may be integrated in a matrix, that is, a bionic flexible tactile sensing system is integrated by utilizing a plurality of the bionic flexible tactile sensors in a matrix arrangement.

[0056] Specifically, the electrode layers in each of the bionic flexible tactile sensors are gathered together to form a pole ear, and the remaining layers are stacked in sequence, thereby obtaining a bionic flexible tactile sensing system.

[0057] In a preferred embodiment, Figure 4 As shown, the bionic flexible tactile sensing system is composed of a 4×4 sensing unit matrix, wherein each sensing unit is the bionic flexible tactile sensor.

[0058] Specifically, the bionic flexible tactile sensing system can adjust the detection area according to the application scenario, and the optional schemes are regular arrays of 3×3, 5×5, etc., and irregular arrays of 3×4, 4×5, etc.

[0059] In addition, Figure 5 As shown, the present invention also provides a method for preparing a bionic flexible tactile sensor, comprising the steps of:

[0060] Step S10: forming a base layer on the substrate;

[0061] Step S20: forming an electrode layer on the base layer;

[0062] Step S30: mixing the PZT nanoparticles with the PDMS precursor solution, and adding the PDMS curing agent to obtain a PZT@PDMS piezoelectric sensitive material colloid;

[0063] Step S40: using a mask to apply the PZT@PDMS piezoelectric sensitive material colloid to the surface of the electrode layer to obtain a PZT@PDMS piezoelectric sensitive layer;

[0064] Step S50: forming a flexible deformation layer and a rigid pressure amplification layer in sequence by coating on the PZT@PDMS piezoelectric sensing sensitive layer, and performing etching to form a crack unit to obtain a bionic flexible tactile sensor.

[0065] In this embodiment, PZT nanoparticles are mixed with a PDMS precursor solution to form a flexible piezoelectric material, namely the PZT@PDMS piezoelectric sensing sensitive layer 30, and then the base layer 10, the electrode layer 20, the PZT@PDMS piezoelectric sensing sensitive layer 30, the flexible deformation layer 40 and the rigid pressure amplification layer 50 are formed into a "hard-soft-hard" structure through a "bottom-up" stacking manufacturing step, and a plurality of crack units are provided from the rigid pressure amplification layer 50 to the PZT@PDMS piezoelectric sensing sensitive layer 30 to obtain a scorpion-like slit receptor, thereby realizing the strain concentration effect of the bionic flexible tactile sensor at the soft material and improving the sensitivity of tactile signal detection.

[0066] Specifically, the bionic flexible tactile sensor prepared by this method has high sensitivity, high resolution, fast response time, high flexibility and stable electrical properties, and the preparation process is simple and can be industrialized.

[0067] In some embodiments, in step S10, quartz glass is used as the substrate, but is not limited thereto.

[0068] In a preferred embodiment, a polyimide solution is used as a base solution, and step S10 comprises: cleaning the quartz glass with acetone, anhydrous ethanol and deionized water in sequence, spin-coating the polyimide solution onto the cleaned quartz glass, leveling and pre-curing at room temperature, and baking at 200° C.-250° C. for 20 minutes-35 minutes through step-by-step heating to obtain a base layer; baking after step-by-step heating can reduce the thermal stress generated by the temperature gradient inside the material, thereby reducing the risk of cracking or deformation.

[0069] In some embodiments, the mass fraction of the polyimide solution is 10%-15%; preferably, the mass fraction of the polyimide solution can be but is not limited to 10%, 12%, or 15%.

[0070] In some embodiments, the polyimide solution is spin-coated onto the cleaned quartz glass at a spin-coating speed of 900 rpm-1200 rpm and a spin-coating time of 100 seconds-130 seconds. Preferably, the spin-coating speed is 1000 rpm and the spin-coating time is 120 seconds.

[0071] In some embodiments, in step S20, forming an electrode layer step on the base layer includes: depositing electrode material on the base layer, and then removing the material by photolithography or laser direct writing to obtain a patterned electrode layer.

[0072] In some embodiments, the particle size of the PZT nanoparticles is 600 nm-950 nm.

[0073] In a preferred embodiment, the particle size of the PZT nanoparticles is 800 nm.

[0074] In some embodiments, in the PZT@PDMS piezoelectric sensitive material colloid, the mass ratio of PZT nanoparticles to PDMS is 2:(0.25-0.5); when the mass ratio of the PZT nanoparticles to the PDMS is controlled within the above range, flexibility and high piezoelectric response can coexist.

[0075] In some embodiments, the mass ratio of the PZT nanoparticles to the PDMS is 2:0.33, at which the flexibility and high-voltage electrical response of the bionic flexible tactile sensor are optimal.

[0076] In some embodiments, the step S50 specifically includes: fixing the shape of the PZT@PDMS piezoelectric sensing sensitive layer with a mold, curing and covering a flexible deformation layer, and then using a laser to cut a rigid pressure amplification thin plate of corresponding size, and connecting the rigid pressure amplification layer to the flexible deformation layer by chemical bonding.

[0077] Specifically, the rigid pressure amplification layer is connected to the flexible deformation layer by chemical bonding, including the following steps: using anhydrous ethanol and deionized water to clean the surfaces of the flexible deformation layer and the rigid pressure amplification layer, respectively, and ultrasonically treating them for 5 minutes. After drying with nitrogen, they are treated with O2 plasma in a chemical dry etching machine with a power of 5kW for 5 minutes. The flexible deformation layer is immersed in a γ-glycidyloxypropyltrimethoxysilane (GPTMS) aqueous solution, and the rigid pressure amplification layer material is immersed in a (3-aminopropyltriethoxysilane (APTES) aqueous solution. A press is used to pressurize and keep the bonding for 2 hours at room temperature. This bonding method can make the interface between the flexible deformation layer and the rigid pressure amplification layer more firmly bonded, and enhance the stability and durability of the sensor.

[0078] In some embodiments, the mask in step S40 is prepared by laser cutting or 3D printing, and the PZT@PDMS piezoelectric sensitive layer is prepared by scraping PZT@PDMS piezoelectric sensitive material colloid on the electrode surface after aligning the mask with the substrate.

[0079] In addition, the present invention also provides an application of a bionic flexible tactile sensor in a manipulator.

[0080] In some embodiments, the bionic flexible tactile sensor is applied to a manipulator, which has the advantages of passive driving mode and high stretchability, and can achieve high-resolution tactile sensing, so that the manipulator has higher sensitivity and self-powered advantages in terms of clamping force.

[0081] The following examples are further given to illustrate the present invention in detail. It should also be understood that the following examples are only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the above content of the present invention belong to the scope of protection of the present invention.

[0082] Example 1

[0083] This embodiment provides a bionic flexible tactile sensor, and the preparation steps are as follows:

[0084] 1) Preparation of PI substrate layer: The quartz glass was cleaned with acetone, anhydrous ethanol and deionized water in turn, and a 12% polyimide solution was spin-coated on the quartz glass at a speed of 1000 rpm for 120 seconds. After leveling and pre-curing at room temperature, the quartz glass was baked at 250°C for 30 minutes after step-by-step heating. The thermal stress generated by the temperature gradient inside the material can be reduced, thereby reducing the risk of cracking or deformation. The thickness of the PI substrate layer is 20 μm, the width is 10 mm, and the length is 15 mm;

[0085] 2) preparing an Au electrode layer: depositing Au on the surface of the PI substrate layer obtained in step 1), and processing it by photolithography or laser direct writing to remove the material to obtain a patterned Au electrode layer with a thickness of 200 nm;

[0086] 3) Preparation of a PZT@PDMS piezoelectric sensing sensitive layer: PZT nanoparticles with a particle size of 800 nm are mixed with a PDMS precursor solution at a mass ratio of 2:0.33, and the PDMS curing agent ratio is adjusted to obtain a viscous PZT@PDMS piezoelectric sensitive material colloid; a mask is prepared by laser cutting or 3D printing (the template thickness is 300 μm, and the strip PZT@PDMS piezoelectric sensing sensitive unit has a width of 1 mm, a length of 10 mm, and a spacing of 0.5 mm); the PZT@PDMS piezoelectric sensitive material colloid is scraped onto the surface of the Au electrode layer obtained in step 2) by using the mask, and the PZT@PDMS piezoelectric sensing sensitive layer is obtained after curing;

[0087] 4) Preparation of PDMS flexible deformation layer: On the PZT@PDMS piezoelectric sensing sensitive layer obtained in step 3), a mold is used to fix the shape, and a layer of PDMS with a thickness of 500 μm is solidified and covered as a flexible deformation layer;

[0088] 5) Preparation of PMMA rigid pressure amplification layer: laser cutting of a PMMA sheet of corresponding size with a thickness of 800 μm, and connecting the PMMA sheet to the PDMS flexible deformation layer obtained in step 4) by chemical bonding;

[0089] The bonding method of the PDMS flexible deformation layer and the PMMA rigid pressure amplification layer comprises the steps of: using anhydrous ethanol and deionized water to clean the surfaces of the PDMS and PMMA, respectively, and ultrasonically treating them for 5 minutes, drying them with nitrogen, and then treating them with O2 plasma in a chemical dry etching machine with a power of 5 kW for 5 minutes. The PDMS is immersed in a γ-glycidyloxypropyltrimethoxysilane (GPTMS) aqueous solution, and the PMMA material is immersed in a (3-aminopropyltriethoxysilane (APTES) aqueous solution, and a press is used to pressurize and keep bonding for 2 hours at room temperature.

[0090] 6) Preparation of bionic crack structure: The sensing structure composed of multiple layers obtained in step 1) to step 5) is processed by laser etching to form a crack structure similar to the scorpion surface strain sensor. The crack here penetrates the PMMA sheet (i.e., the crack extends from the PMMA rigid pressure amplification layer to the PZT@PDMS piezoelectric sensing sensitive layer). Its structure is as follows: Figure 1 As shown, the width of the cracks is 500 μm and the spacing is uniformly 1 mm.

[0091] The voltage response test of the bionic flexible tactile sensor prepared in this embodiment specifically includes: voltage response tests of three states of touch, point touch and press are performed on the bionic flexible tactile sensor unit, and the results are as follows: Figure 6As shown, the average voltage response in the touch state is about 240mV, the average voltage response in the touch state is about 750mV, and the average voltage response in the press state is about 1.1V.

[0092] In summary, the present invention provides a bionic flexible tactile sensor and a preparation method and application thereof. The bionic flexible tactile sensor includes a substrate layer, an electrode layer, a PZT@PDMS piezoelectric sensing sensitive layer, a flexible deformation layer and a rigid pressure amplification layer stacked in sequence; the PZT@PDMS piezoelectric sensing sensitive layer includes a plurality of strip-shaped PZT@PDMS piezoelectric sensing sensitive units arranged at intervals; the flexible deformation layer is partially embedded in the intervals between the strip-shaped PZT@PDMS piezoelectric sensing sensitive units; the bionic flexible tactile sensor is provided with a plurality of crack units from the rigid pressure amplification layer to the PZT@PDMS piezoelectric sensing sensitive layer. The bionic flexible tactile sensor of the present invention draws on the strain amplification structure of the scorpion slit receptor in nature in terms of structure. The exoskeleton epidermis on both sides of the scorpion slit is rigid, while the subcutaneous tissue part and the ends of the slit are flexible. By utilizing the "hard-soft-hard" structure of the biological surface sensor slit, the strain concentration effect at the soft material can be achieved, thereby improving the sensitivity of tactile signal detection. Therefore, the present invention utilizes a substrate layer, an electrode layer, a PZT@PDMS piezoelectric sensing sensitive layer, a flexible deformation layer and a rigid pressure amplification layer stacked in sequence to form a "hard-soft-hard" structure, and a number of crack units are provided from the rigid pressure amplification layer to the PZT@PDMS piezoelectric sensing sensitive layer to obtain a scorpion-like slit receptor, which has good uniformity and passive driving mode, thereby realizing high-resolution tactile sensing.

[0093] It should be understood that the application of the present invention is not limited to the above examples. For ordinary technicians in this field, improvements or changes can be made based on the above description. All these improvements and changes should fall within the scope of protection of the claims attached to the present invention.

Claims

1. A bionic flexible tactile sensor, characterized in that: It includes a substrate layer, an electrode layer, a PZT@PDMS piezoelectric sensing layer, a flexible deformation layer and a rigid pressure amplification layer stacked in sequence; The PZT@PDMS piezoelectric sensing sensitive layer includes a plurality of strip-shaped PZT@PDMS piezoelectric sensing sensitive units arranged at intervals; the flexible deformation layer is partially embedded in the intervals between the strip-shaped PZT@PDMS piezoelectric sensing sensitive units; the bionic flexible tactile sensor is provided with a plurality of crack units from the rigid pressure amplification layer to the PZT@PDMS piezoelectric sensing sensitive layer.

2. The bionic flexible tactile sensor according to claim 1, characterized in that: The material of the base layer is selected from one of polyimide, polyethylene terephthalate, and polyetheretherketone; and / or the material of the electrode layer is selected from one of Au, Ag, Cu, Cr, graphite, copper-tungsten alloy, and silver-tungsten alloy.

3. The bionic flexible tactile sensor according to claim 1, characterized in that: The material of the flexible deformation layer is selected from one of PDMS, silica gel, and ecoflex; the material of the rigid pressure amplification layer is selected from one of polymethyl methacrylate and glass.

4. The bionic flexible tactile sensor according to claim 1, characterized in that: The interval between two adjacent strip-shaped PZT@PDMS piezoelectric sensing sensitive units is 0.4 mm-0.6 mm.

5. The bionic flexible tactile sensor according to claim 1, characterized in that: The crack width of the crack unit is 500 μm-1000 μm; the distance between two crack units is 1 mm-2 mm.

6. The bionic flexible tactile sensor according to claim 1, characterized in that: The thickness of the base layer is 15μm-25μm; the thickness of the electrode layer is 150nm-250nm; the thickness of the PZT@PDMS piezoelectric sensing sensitive layer is 250μm-350μm; the thickness of the flexible deformation layer is 400μm-500μm; and the thickness of the rigid pressure amplification layer is 400μm-500μm.

7. A method for preparing a bionic flexible tactile sensor according to any one of claims 1 to 6, characterized in that: Includes steps: forming a base layer on a substrate; forming an electrode layer on the base layer; The PZT nanoparticles are mixed with the PDMS precursor solution, and the PDMS curing agent is added to obtain the PZT@PDMS piezoelectric sensitive material colloid; Using a mask plate, the PZT@PDMS piezoelectric sensitive material colloid is coated on the surface of the electrode layer to obtain a PZT@PDMS piezoelectric sensitive layer; A flexible deformation layer and a rigid pressure amplification layer are sequentially formed by coating on the PZT@PDMS piezoelectric sensing sensitive layer, and a crack unit is formed by etching, thereby obtaining a bionic flexible tactile sensor.

8. The method for preparing the bionic flexible tactile sensor according to claim 7, characterized in that: The particle size of the PZT nanoparticles is 600nm-950nm.

9. The method for preparing the bionic flexible tactile sensor according to claim 7, characterized in that: In the PZT@PDMS piezoelectric sensitive material colloid, the mass ratio of PZT nanoparticles to PDMS is 2:(0.25-0.5).

10. Use of the bionic flexible tactile sensor according to any one of claims 1 to 6 in a manipulator.

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