High-density flexible piezoresistive fingertip tactile sensor and preparation method thereof
Through the haptic sensor designed with high-density electrode array and memory wire mesh, the problems of insufficient resolution and difficulty in replacing flexible layers of traditional haptic sensors are solved, and high-precision haptic perception and wide application are achieved.
Patent Information
- Application Number
- CN202510356366.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-25
- Publication Date
- 2025-07-04
AI Technical Summary
Traditional haptic sensors are difficult to simulate the tactile characteristics of human fingers, and the resolution and sensitivity are insufficient, and the flexible layer of the fingertip tactile sensor surface is easily reduced during replacement after wear.
The high-density electrode array, flexible conductive layer and memory wire mesh design are adopted, combined with machine learning algorithms, to accurately capture pressure changes, and conveniently replace the flexible layer through anti-disassembly and boss structures, gradient memory wire mesh enhances fatigue resistance.
It improves the spatial resolution and measurement accuracy of the tactile sensor, ensures stable performance in complex environments, strong adaptability, reduces the difficulty of replacing flexible layers, and expands the application range of robots.
Smart Images
Figure CN120253020A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of robot interaction technology, and particularly to a high-density flexible piezoresistive fingertip tactile sensor and a preparation method thereof. Background Art
[0002] With the development of robot technology and artificial intelligence, humanoid robots are increasingly widely used in industrial, medical, service and other fields. In order to achieve more natural and efficient interaction, robots need to have tactile perception capabilities similar to those of humans, so as to better understand and respond to the external environment.
[0003] Traditional tactile sensors are difficult to fully simulate the tactile characteristics of human fingers, and at the same time have limitations in terms of resolution, sensitivity, etc., and cannot adapt to the complex application scenarios of humanoid robots. Therefore, in the field of robot perception, there is an urgent need for a tactile sensor with high integration, high resolution, high density and bionic tactile characteristics as a device for humanoid robots to interact with the environment. Moreover, after the fingertip tactile sensor has been used for a long time, the surface flexible layer of the fingertip tactile sensor will be worn and needs to be replaced. During the replacement process, the sensing layer may be misaligned due to inconvenient assembly and other reasons, which affects the sensing accuracy. How to ensure that the fingertip tactile sensor can still maintain a high sensing accuracy after the surface flexible layer is replaced is also an urgent problem to be solved. Summary of the Invention
[0004] In order to improve the problem that existing tactile sensors are difficult to meet the high requirements of humanoid robots for human-like tactile perception during long-term use, this application provides a high-density flexible piezoresistive fingertip tactile sensor and a preparation method thereof.
[0005] In a first aspect, a high-density flexible piezoresistive fingertip tactile sensor provided by this application adopts the following technical solution: A high-density flexible piezoresistive fingertip tactile sensor includes a fingertip base, electrode plates, a conductive layer, a flexible conduction layer and a signal acquisition module. A plurality of protruding electrode pairs arranged in a matrix are provided on the electrode plates, and physical isolation is performed between each of the protruding electrode pairs by copper plating. A plurality of tiny deformable protrusions corresponding one-to-one to the plurality of protruding electrode pairs are provided on one side of the conductive layer close to the electrode plates. The flexible conduction layer is used to transfer external deformation to the conductive layer, and the signal acquisition module is used to collect tactile data and send it to a host computer; When the flexible conduction layer is subjected to an external force, the position and magnitude of the force applied to the tactile sensor are determined according to the microstructural contact mode between the conductive layer and the electrode plates and the resistance change caused by the deformation of the conductive layer; The fingertip base is provided with a receiving groove for accommodating the electrode plate and the conductive layer. The fingertip base is provided with an annular fixing groove on the wall of the receiving groove. One side of the flexible conduction layer close to the base has a convex portion that is inserted and adapted to the receiving groove, and a flange that is fixedly connected to the outer peripheral wall of the convex portion and is engaged and adapted to the annular fixing groove is provided.
[0006] Furthermore, one side of the convex portion close to the electrode plate has a fitting groove that is inserted and adapted to the conductive layer. The convex portion has an anti-detachment edge at the mouth of the fitting groove for pressing the conductive layer against the bottom wall of the fitting groove, and a boss for clamping the conductive layer against the wall of the fitting groove on the side of the convex portion away from the anti-detachment edge.
[0007] Furthermore, the thickness of the conductive layer is less than the thickness of the boss. When the convex portion is inserted into the receiving groove, the convex portion clamps the electrode plate against the wall of the receiving groove.
[0008] Furthermore, a shape memory metal wire mesh is provided on one side of the conductive layer close to the electrode plate, and its metal wires avoid the contact area of the raised electrode pair.
[0009] Furthermore, the shape memory metal wire mesh is embedded in the conductive layer.
[0010] Furthermore, the shape memory metal wire mesh is arranged in a gradient manner. Its wire mesh density is 150 mesh to 250 mesh in the central region and gradually decreases to 80 mesh to 120 mesh towards the edge region; and / or, the thickness of the shape memory metal wire mesh shows a decreasing trend from the central region to the edge region; and / or, the nickel content in the alloy composition of the shape memory metal wire mesh shows a decreasing trend from the central region to the edge region.
[0011] Furthermore, an insulating coating is provided on the surface of the shape memory metal wire mesh.
[0012] Furthermore, the fingertip base is provided with a mounting groove for accommodating a wiring terminal on the bottom wall of the receiving groove, and a heat dissipation port communicating with the mounting groove and a wire groove communicating with the receiving groove are provided on the fingertip base.
[0013] In a second aspect, a method for manufacturing a high-density flexible piezoresistive fingertip tactile sensor provided by the present application, based on the above-mentioned high-density flexible piezoresistive fingertip tactile sensor, includes the following steps: S1. Manufacturing the flexible conduction layer, designing a mold according to the shape and size of the flexible conduction layer, and casting with a resin material; S2. Manufacturing the conductive layer, designing a mold according to the shape and size of the conductive layer, and casting with a PDMS / CNT composite material; S3. Manufacturing the electrode plate, soldering a plurality of the raised electrode pairs to corresponding pads on the electrode plate with a soldering iron and solder; S4. Manufacture the fingertip base. Obtain the three-dimensional model of the fingertip base through modeling, and then use polyurethane material to print the fingertip base through 3D printing technology; S5. Package the tactile sensor. Connect the electrode plate and the flexible cable and place them in the accommodation groove. Install the conductive layer on the flexible conduction layer, and fasten the flexible conduction layer to the fingertip base through elastic clamping; S6. Calibrate the pressure of the sensor. Use a standard force sensor to apply a series of known pressure values to the assembled flexible tactile sensor, record the readings of the standard force sensor, the voltage output values of the sensing electrode points, and the measurement results of the pressure sensor. Collect data under multiple different pressure conditions to establish the corresponding relationship between the input pressure and the sensor output. Use a neural model to fit and train the recorded data to determine the best function model describing the relationship between the two. Finally, the function model obtained through the above calibration steps is applied to the data processing algorithm of the tactile sensor to ensure its ability to provide high-precision pressure perception.
[0014] Furthermore, in step S2, when pouring the conductive layer, a shape memory metal wire mesh is embedded in its mold, and the metal wires of the shape memory metal wire mesh avoid the contact area of the raised electrode pair. The shape memory metal wire mesh is printed from nickel-titanium alloy powder. When necessary, an insulating layer is also sprayed on the surface of the shape memory metal wire mesh.
[0015] In summary, the present application includes at least one of the following beneficial technical effects: 1. The present application adopts a high-density electrode array, which can accurately capture subtle pressure changes, significantly improving the spatial resolution and measurement accuracy of the tactile sensor, thus better simulating the tactile characteristics of the human finger; and by using special flexible conduction layer and conductive layer materials, the tactile sensor can maintain stable performance in various bending states, ensuring reliability and adaptability in complex environments; 2. Through the setting of the anti-disengagement edge and the boss on the flexible conduction layer, it is convenient for the assembly of the tactile sensor and can achieve precise positioning of the conductive layer on the flexible conduction layer after the flexible conduction layer is replaced; 3. By embedding the shape memory metal wire mesh in the conductive layer in a gradient manner, the anti-fatigue performance of the high-frequency contact area of the conductive layer can be strengthened specifically, while reducing the rigidity of the edge area, avoiding the problem of limited deformation of the flexible conduction layer caused by excessive overall rigidity; 4. The materials and manufacturing processes adopted in the present invention are relatively simple and the cost is low, enabling large-scale production; and due to its high precision, flexibility and low cost, the tactile sensor of the present invention is applicable to a variety of high-end application scenarios, such as precision assembly, medical surgery assistance, dangerous environment detection, etc., greatly expanding the application scope and functions of the robot. Description of the Drawings
[0016] To more clearly illustrate the technical solutions in the present invention or the prior art, the following will briefly introduce the accompanying drawings required for use in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can also be obtained based on these drawings.
[0017] Figure 1 is the overall structural schematic diagram of the embodiment of the present application; Figure 2 is the exploded structural schematic diagram of the embodiment of the present application; Figure 3 is the structural schematic diagram of the electrode plate of the embodiment of the present application; Figure 4 is the circuit schematic diagram of the embodiment of the present application; Figure 5 is the structural schematic diagram of the fingertip base of the embodiment of the present application; Figure 6 is the structural schematic diagram of the flexible conductive layer from two perspectives of the embodiment of the present application; Figure 7 is the structural schematic diagram of the conductive layer of the embodiment of the present application; Figure 8 is the end view of the conductive layer of the embodiment of the present application.
[0018] Reference numerals: 1, fingertip base; 11, receiving groove; 12, annular fixing groove; 13, wire groove; 14, heat dissipation port; 15, mounting groove; 2, electrode plate; 21, excitation electrode; 22, sensing electrode; 23, reference resistor; 24, terminal; 3, conductive layer; 31, micro deformable protrusions; 32, shape memory metal wire mesh; 4, flexible conductive layer; 41, fingerprint-like micro protrusions; 42, convex part; 43, flange; 44, boss; 45, embedding groove; 46, anti-detachment edge; 5, FPC flexible cable. Detailed implementation manners
[0019] To make the objectives, technical solutions and advantages of the present invention clearer, the following will clearly and completely describe the technical solutions in the present invention in conjunction with the accompanying drawings in the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.
[0020] Refer to Figure 1, Figure 2 and Figure 3 , embodiments of the present application disclose a high - density flexible piezoresistive fingertip tactile sensor, which includes a fingertip base 1, an electrode plate 2, a conductive layer 3, a flexible conduction layer 4, and a signal acquisition module. The electrode plate 2, the conductive layer 3, and the flexible conduction layer 4 are sequentially arranged on the fingertip base 1.
[0021] Referring to Figure 2 , a plurality of raised electrode pairs arranged in a matrix and several reference resistors 23 are provided on the electrode plate 2. Physical isolation is performed between each raised electrode pair through copper plating. The raised electrode pair includes an excitation electrode 21 and a sensing electrode 22 that are spaced apart and are in the shape of hemispherical protrusions. The distribution of the raised electrode pairs on the electrode plate 2 can be completely covered by the conductive layer 3, ensuring the responsiveness of each measurement channel; and the excitation electrode 21 and the sensing electrode 22 are made by surface soldering on the electrode plate 2, and the signal is connected to the FPC flexible cable 5 through the wire - to - board terminal 24 and led out from the fingertip base 1.
[0022] Referring to Figure 3 and Figure 4 , a plurality of tiny deformable protrusions 31 corresponding one - to - one with the plurality of raised electrode pairs are provided on the side of the conductive layer 3 close to the electrode plate 2. Preferably, when the tactile sensor is not subjected to external stimuli, there is no contact between the raised electrode pairs and the tiny deformable protrusions 31. When the flexible conduction layer 4 is subjected to external stimuli, the tiny deformable protrusions 31 on the conductive layer 3 come into contact with the raised electrode pairs on the electrode plate 2. As the pressure applied to the flexible conduction layer 4 increases, the deformation of the tiny deformable protrusions 31 also increases, the resistance between the raised electrode pairs decreases, the current increases, and thus the voltage on the reference resistor 23 on the electrode plate 2 increases. These signals are output through the conditioning circuit of the signal acquisition module. After measuring the change in the output voltage, the coordinates of the corresponding contact point, the magnitude of the force, and the direction of the force can be obtained through machine learning.
[0023] The flexible conduction layer 4 is used to transfer external deformation to the conductive layer 3, and fingerprint - like micro - protrusions 41 are provided on the side thereof facing away from the conductive layer 3, which can increase the contact details between the tactile sensor and the object surface, and at the same time increase the friction force to better grasp and operate the object. Moreover, when the same force is applied to the tactile sensor, by contacting objects with different materials and textures, different electrical signals are output, and thus the material and surface information of the object can be judged. It should be noted that in the present application, there is no limitation on the materials of the conductive layer 3 and the flexible conduction layer. Any material that satisfies the piezoresistive effect can be used as the conductive layer 3. Preferably, it is made of a mixture obtained by mixing polydimethylsiloxane and carbon nanotubes in a certain proportion. Any material that can completely return to the original deformed shape after the external force is removed can be used as the flexible conduction layer in the present application. Preferably, it is made by flexible resin casting.
[0024] The signal acquisition module is used to collect the resistance changes of the raised electrode pairs, process the data, and send it to the host computer.
[0025] It should be understood that the fingertip base 1 in this application provides necessary protection, connection, and encapsulation functions, while the signal acquisition module is used to collect and process signals. Both are auxiliary components of the tactile sensor. In this application, the electrode plate 2, the conductive layer 3, and the flexible conduction layer 4 together constitute the core sensitive part of the flexible tactile sensor. Any flexible fingertip tactile sensor that uses the electrode plate 2, the conductive layer 3, and the flexible conduction layer 4 provided in this application as the tactile sensitive part, whether it contains a main housing and / or a data acquisition device, is within the protection scope of this application.
[0026] Thus, when the tactile sensor of this application is externally stimulated, the micro deformable protrusions 31 on the conductive layer 3 contact the raised electrode pairs on the electrode plate 2. As the pressure applied to the flexible conduction layer 4 increases, the deformation of the micro deformable protrusions 31 also increases, the resistance between the raised electrode pairs decreases, and the current increases, resulting in an increase in the voltage across the reference resistor 23 on the electrode plate 2. The signal is output through the conditioning circuit of the signal acquisition module. After measuring the change in the output voltage, the coordinates of the contact point, the magnitude and direction of the force are obtained through machine learning; and then the actual parameters of the external force are calculated through pre calibration. Any micro deformable protrusion 31 of the above tactile sensor is paired with any raised electrode pair one by one, and this interlocking relationship enhances the sensitivity of the tactile sensor, enabling it to produce a significant response even under a small stimulus, making the tactile sensor of this application capable of providing a more delicate tactile feedback.
[0027] For the convenience of assembling the tactile sensor of this application and replacing the flexible conduction layer 4, referring to Figure 5 and Figure 6 , the fingertip base 1 has a receiving groove 11 for accommodating the electrode plate 2 and the conductive layer 3. The fingertip base 1 is provided with an annular fixing groove 12 on the groove wall of the receiving groove 11. The flexible conduction layer 4 has a convex portion 42 on the side close to the base, which is inserted and adapted to the receiving groove 11. A flange 43 that is engaged and adapted to the annular fixing groove 12 is fixedly connected to the outer peripheral wall of the convex portion 42.
[0028] Moreover, the convex portion 42 has an insertion groove 45 on the side close to the electrode plate 2, which is inserted and adapted to the conductive layer 3. The convex portion 42 has an anti detachment edge 46 at the notch of the insertion groove 45 for pressing the conductive layer 3 against the bottom wall of the insertion groove 45. The convex portion 42 has a boss 44 on the side away from the anti detachment edge 46 for clamping the conductive layer 3 to the groove wall of the insertion groove 45. The thickness of the conductive layer 3 is less than the thickness of the boss 44. When the convex portion 42 is inserted into the receiving groove 11, the convex portion 42 clamps the electrode plate 2 to the groove wall of the receiving groove 11.
[0029] Moreover, the fingertip base 1 is provided with an installation groove 15 for accommodating the wiring terminal 24 at the bottom wall of the accommodation groove 11, and a heat dissipation port 14 communicating with the installation groove 15 and a wire groove 13 communicating with the accommodation groove 11 are provided on the fingertip base 1.
[0030] Thus, when encapsulating the tactile sensor of the present application, first insert the FPC flexible cable 5 from the end of the wire groove 13 on the fingertip base 1, connect the electrode plate 2 and the FPC flexible cable 5 and then place them into the accommodation groove 11 and the installation groove 15 of the fingertip base 1, and connect the other end of the FPC flexible cable 5 to the signal acquisition module. Then insert the conductive layer 3 into the embedding groove 45 of the flexible conduction layer 4, and clamp the conductive layer 3 on the flexible conduction layer 4 through the anti-disengagement edge 46 and the convex platform 44 on the flexible conduction layer 4. Finally, insert the convex part 42 on the flexible conduction layer 4 into the accommodation groove 11 on the fingertip base 1, and make the flange 43 snap into the annular fixing groove 12, so that the flexible conduction layer 4 is tightly connected to the fingertip base 1.
[0031] When replacing the flexible conduction layer 4, just pull out the flexible conduction layer 4 from the fingertip base 1, and at the same time remove the conductive layer 3, replace it with a new flexible conduction layer 4, and install the conductive layer 3 into the new flexible conduction layer 4. Through the arrangement of the anti-disengagement edge 46 and the convex platform 44, accurate positioning of the conductive layer 3 on the flexible conduction layer 4 can be realized after the replacement of the flexible conduction layer 4.
[0032] In addition, to avoid the fatigue accumulation and irreversible deformation caused by the long-term use of the conductive layer 3.
[0033] In other feasible embodiments, referring to Figure 7 and Figure 8 , a shape memory metal wire mesh 32 is provided on the side of the conductive layer 3 close to the electrode plate 2, and its metal wires avoid the contact area of the convex electrode pair. Specifically, the shape memory metal wire mesh 32 is made of nickel-titanium alloy, has a micron-level mesh structure, is gradient-embedded in the lower surface of the conductive layer 3, and avoids the contact area of the convex electrode pair.
[0034] Moreover, the shape memory metal wire mesh 32 is arranged in a gradient manner, and its wire mesh density is 150 mesh to 250 mesh, such as 200 mesh, in the central area (high-frequency contact area) of the tactile sensor, and gradually decreases to 80 mesh to 120 mesh, such as 100 mesh, towards the edge area.
[0035] And / or, the thickness of the shape memory metal wire mesh 32 shows a decreasing trend from the central area to the edge area, such as decreasing from 50 μm to 20 μm.
[0036] And / or, the nickel content in the alloy composition of the shape memory metal wire mesh 32 shows a decreasing trend from the central area to the edge area, such as decreasing from 55% to 50%.
[0037] Therefore, the gradient memory metal mesh 32 structure is realized by depositing nickel-titanium alloy powders of different proportions layer by layer through multi-material 3D printing technology. During the printing process, the powder feeding ratio and laser power are adjusted in real time to ensure the metallurgical bonding and structural continuity of each layer of materials. This design can strengthen the fatigue resistance of the high-frequency contact area of the memory metal mesh 32, while reducing the rigidity of the edge area, avoiding the problem of limited deformation of the conductive layer 3 due to excessive overall rigidity.
[0038] Furthermore, an insulating coating is provided on the surface of the memory metal mesh 32 to reduce possible interference of the memory metal mesh 32 on the protruding electrode pairs.
[0039] Specifically, the insulating coating uses polyimide (PI) as the insulating coating material with a thickness of 2um, and adopts ultrasonic atomization spraying technology; before spraying, the surface is first pre-treated, specifically, the memory metal wire mesh 32 is plasma cleaned (argon atmosphere, power 100W, time 5min) to remove surface oxides and improve the roughness (Ra is increased to 0.5-1μm), and enhance the adhesion of the coating; after spraying, it is cured (step temperature curing: 80℃ pre-baking for 10min→150℃ curing for 30min→250℃ post-curing for 1h to form a dense insulating film). This solution not only ensures the insulating performance of the insulating coating, but also takes into account the deformation function of the memory metal wire mesh 32 and the overall flexibility of the tactile sensor, and is suitable for the anti-fatigue design and long life requirements of high-density tactile sensors.
[0040] The present application also discloses a method for preparing a high-density flexible piezoresistive fingertip tactile sensor. Based on the above-mentioned high-density flexible piezoresistive fingertip tactile sensor, the following technical solution is adopted: A method for preparing a high-density flexible piezoresistive fingertip tactile sensor comprises the following steps: S1. Making a flexible conductive layer 4, designing a mold according to the shape and size of the flexible conductive layer 4, and pouring the resin material; S2. Making a conductive layer 3, designing a mold according to the shape and size of the conductive layer 3, and casting the PDMS / CNT mixed material; S3. Making an electrode plate 2, soldering a plurality of raised electrode pairs on the electrode plate 2 at the corresponding pads with an electric soldering iron and solder; S4. Making a fingertip base 1, obtaining a three-dimensional model of the fingertip base 1 by modeling, and then printing the fingertip base 1 using a polyurethane material by 3D printing technology; S5. Encapsulate the tactile sensor, connect the electrode plate 2 and the FPC flexible cable 5 and place them in the receiving groove 11, install the conductive layer 3 on the flexible conductive layer 4, and fasten the flexible conductive layer 4 to the fingertip base 1 by elastic snap fastening; S6. Calibrate the pressure of the sensor. Apply a series of known pressure values to the assembled flexible tactile sensor using a standard force sensor. Record the readings of the standard force sensor, the voltage output values of the sensing electrodes 22, and the measurement results of the pressure sensor. Collect data under multiple different pressure conditions to establish the corresponding relationship between the input pressure and the sensor output. Use a neural model to fit and train the recorded data to determine the best function model describing the relationship between the two. Finally, the function model obtained through the above calibration steps is applied to the data processing algorithm of the tactile sensor to ensure its ability to provide high-precision pressure perception.
[0041] Among them, in step S2, when pouring the conductive layer 3, a shape memory metal wire mesh 32 is embedded in its mold, and the metal wires of the shape memory metal wire mesh 32 avoid the contact area of the convex electrode pair. The shape memory metal wire mesh 32 is printed from nickel-titanium alloy powder. If necessary, an insulating layer is also sprayed on the surface of the shape memory metal wire mesh 32.
[0042] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.
Claims
1. A high-density flexible piezoresistive fingertip tactile sensor, comprising a fingertip base, an electrode plate, a conductive layer, a flexible conduction layer and a signal acquisition module, characterized in that, A plurality of convex electrode pairs arranged in a matrix are provided on the electrode plate, and physical isolation is performed between each of the convex electrode pairs by copper plating. A plurality of tiny deformable protrusions corresponding to the plurality of convex electrode pairs one by one are provided on one side of the conductive layer close to the electrode plate. The flexible conduction layer is used to transfer external deformation to the conductive layer, and the signal acquisition module is used to acquire tactile data and send it to the host computer; When an external force is applied to the flexible conduction layer, the position and magnitude of the force applied to the tactile sensor are determined according to the microstructural contact mode between the conductive layer and the electrode plate and the resistance change caused by the deformation of the conductive layer; The fingertip base has a receiving groove for receiving the electrode plate and the conductive layer. The fingertip base is provided with an annular fixing groove on the groove wall of the receiving groove. One side of the flexible conduction layer close to the base has a convex portion adapted to be inserted and fitted into the receiving groove, and a flange adapted to be snap-fitted into the annular fixing groove is fixedly connected to the outer peripheral wall of the convex portion.
2. The high-density flexible piezoresistive fingertip tactile sensor according to claim 1, wherein One side of the convex portion close to the electrode plate has a fitting groove adapted to be inserted and fitted with the conductive layer. The convex portion has an anti-detachment edge at the opening of the fitting groove for pressing the conductive layer against the bottom wall of the fitting groove, and a convex platform for clamping the conductive layer against the groove wall of the fitting groove on the side of the convex portion away from the anti-detachment edge.
3. The high-density flexible piezoresistive fingertip tactile sensor according to claim 2, characterized in that, The thickness of the conductive layer is less than the thickness of the convex platform. When the convex portion is inserted into the receiving groove, the convex portion clamps the electrode plate on the groove wall of the receiving groove.
4. A high-density flexible piezoresistive fingertip tactile sensor according to any one of claims 1-3, characterized in that A shape memory metal wire mesh is provided on one side of the conductive layer close to the electrode plate, and its metal wires avoid the contact areas of the convex electrode pairs.
5. The high-density flexible piezoresistive fingertip tactile sensor according to claim 4, characterized in that, The shape memory metal wire mesh is embedded in the conductive layer.
6. The high-density flexible piezoresistive fingertip tactile sensor according to claim 5, characterized in that, The shape memory metal wire mesh is arranged in a gradient manner, and its wire mesh density is 150 mesh to 250 mesh in the central region and gradually decreases to 80 mesh to 120 mesh towards the edge region; And / or, the thickness of the shape memory metal wire mesh shows a decreasing trend from the central region to the edge region; And / or, the nickel content in the alloy composition of the shape memory metal wire mesh shows a decreasing trend from the central region to the edge region.
7. A high-density flexible piezoresistive fingertip tactile sensor according to claim 5, characterized in that, An insulating coating is provided on the surface of the shape memory metal wire mesh.
8. A high-density flexible piezoresistive fingertip tactile sensor according to claim 1, characterized in that, The fingertip base is provided with a mounting groove for receiving a wiring terminal on the bottom wall of the receiving groove, and a heat dissipation port communicating with the mounting groove and a wire groove communicating with the receiving groove are provided on the fingertip base.
9. A preparation method of a high-density flexible piezoresistive fingertip tactile sensor, based on a high-density flexible piezoresistive fingertip tactile sensor according to any one of claims 1-8, characterized in that, Including the following steps: S1. Fabricate the flexible conduction layer, design a mold according to the shape and size of the flexible conduction layer, and cast it with a resin material; S2. Fabricate the conductive layer, design a mold according to the shape and size of the conductive layer, and cast it with a PDMS / CNT composite material; S3. Fabricate the electrode plate, and solder a plurality of the convex electrode pairs at corresponding pads on the electrode plate with an electric soldering iron and solder; S4. Fabricate the fingertip base, obtain a three-dimensional model of the fingertip base through modeling, and then print the fingertip base using a polyurethane material through 3D printing technology; S5. Package the tactile sensor, connect the electrode plate and the flexible cable and place them in the receiving groove, install the conductive layer on the flexible conduction layer, and fixedly connect the flexible conduction layer to the fingertip base through elastic clamping; S6. Calibrate the pressure of the sensor. Use a standard force sensor to apply a series of known pressure values to the assembled flexible tactile sensor, record the readings of the standard force sensor, the voltage output values of the sensing electrode points, and the measurement results of the pressure sensor, collect data under multiple different pressure conditions to establish the corresponding relationship between the input pressure and the sensor output, and use a neural model to fit and train the recorded data to determine the best function model describing the relationship between the two; finally, the function model obtained through the above calibration steps is applied to the data processing algorithm of the tactile sensor to ensure that it can provide high-precision pressure sensing capabilities.
10. The preparation method of a high-density flexible piezoresistive fingertip tactile sensor according to claim 9, characterized in that, In step S2, when pouring the conductive layer, embed a shape memory metal wire mesh in its mold, and the metal wires of the shape memory metal wire mesh avoid the contact area of the raised electrode pair. The shape memory metal wire mesh is printed from nickel-titanium alloy powder. If necessary, an insulating layer is also sprayed on the surface of the shape memory metal wire mesh.