A flexible capacitive pressure sensing array adapted to a bionic dexterous hand and its fabrication method

Abstract

This invention discloses a flexible capacitive pressure sensing array adapted to a bionic dexterous hand and its fabrication method, belonging to the field of flexible tactile sensor technology. The sensing array comprises a stacked upper flexible substrate, a middle dielectric layer, and a lower flexible substrate. Vertical electrodes are printed on the upper flexible substrate, and horizontal electrodes are printed on the lower flexible substrate. The vertical and horizontal electrodes intersect perpendicularly to form capacitive sensing units, employing a non-uniform bionic layout adapted to the force characteristics of the human hand. The sensing array as a whole adapts to the bionic shape of the five fingers of the palm, with anti-bending curves at the joints. The electrode lines converge at the wrist and connect to an FPC connector. Microstructures are incorporated in the middle dielectric layer to enhance sensing sensitivity. This invention utilizes a microelectronic printing and vacuum thermopressing integrated process to solve the problems of poor flexibility, unreasonable layout, and integration difficulties in existing sensors. It combines high sensing resolution with bending reliability, is suitable for precise dexterous hand operation, and can be mass-produced.

Description

Technical Field

[0001] This invention belongs to the field of flexible tactile sensor technology, specifically relating to a flexible capacitive pressure sensing array adapted to a biomimetic dexterous hand and having a biomimetic non-uniform distribution structure. It also relates to a method for fabricating the sensing array, which can be applied to scenarios such as industrial precision assembly, service robots, medical rehabilitation, and human-machine collaborative interaction. Background Technology

[0002] With the rapid iteration and industrial application of robotics technology, bionic dexterous hands, with their human-like multi-degree-of-freedom movement capabilities and precision manipulation performance, are increasingly widely used in fields such as industrial precision assembly, service robots, medical rehabilitation, and human-machine collaborative interaction. Tactile perception is the core support for the intelligent and precise operation of bionic dexterous hands, and the performance of the flexible pressure sensor array, which serves as the carrier of tactile perception, directly determines the environmental perception accuracy and operational reliability of the dexterous hand.

[0003] Current tactile sensing solutions applied to bionic dexterous hands still face several technical bottlenecks that restrict their large-scale application and cannot fully meet the human-like operation requirements of dexterous hands. First, most sensing solutions use FPC carriers or rigid substrates and rigid electrodes, which lack sufficient substrate flexibility and are difficult to adapt to the large-angle bending and curved surface fitting requirements of dexterous hand joints, seriously affecting the flexibility and environmental adaptability of dexterous hand operation. Second, existing sensor arrays mostly adopt a regular and uniform electrode layout design, without considering human bionics and the actual operating conditions of dexterous hands, and failing to match the different tactile perception needs of different areas of the fingertips, finger pads, and palms, resulting in unreasonable allocation of sensing resources. The fingertips, as the core contact area for precision operation, cannot achieve high-resolution fine texture and small force perception, while the palm, as the core area for grasping and bearing, is difficult to monitor a large range of contact force distribution. Third, existing sensing units mostly adopt a regular rectangular split packaging structure, which has poor fit with the complex bionic curved surface shape of the palm and multiple fingers of a dexterous hand. The multi-zone independent attachment solution not only fails to achieve integrated continuous sensing coverage of the entire palm and all finger joints, but also significantly increases the complexity of wiring and the difficulty of system integration.

[0004] For example, Chinese utility model patent CN222345637U discloses a flexible dexterous hand tactile sensing electronic skin based on FPC. It uses longitudinal and transverse electrodes on an FPC substrate to form a capacitive sensing unit at the electrode intersections. However, this solution uses a rigid FPC substrate, resulting in insufficient overall flexibility and difficulty in adapting to the large-angle repeated bending requirements of dexterous hand joints. Furthermore, it lacks differentiated electrode layouts for different operating areas of the dexterous hand, failing to optimize the allocation of sensing resources. Similarly, Chinese utility model patent CN223877003U discloses a human-hand-like operating device that achieves tactile sensing by attaching flexible electronic skin to the fingertips and knuckles in sections. However, this separate attachment method cannot achieve integrated continuous sensing coverage of the palm and the entire knuckle area. Additionally, the multi-section independent wiring design significantly increases the difficulty of circuit layout and system integration, making it difficult to meet the miniaturization and integration requirements of dexterous hand applications.

[0005] In summary, existing technologies have not yet proposed an integrated flexible capacitive pressure sensor array that can simultaneously achieve biomimetic adaptation to the entire area of ​​the dexterous hand, differentiated allocation of sensing resources, high bending reliability, and low integration difficulty. Developing a tactile sensing solution that meets the above requirements is of great practical significance and application value for promoting the intelligent upgrading and large-scale application of biomimetic dexterous hands. Summary of the Invention

[0006] To address the problems of poor flexibility, unreasonable sensing layout, low fit, difficult integration, and inability to be mass-produced in existing sensor arrays, this invention provides a flexible capacitive pressure sensing array adapted to a bionic dexterous hand and its fabrication method. This array has a bionic shape highly adapted to a dexterous hand, sensitive units distributed differently according to tactile functional requirements, and an optimized flexible circuit layout, enabling multi-point, wide-range, and high-resolution pressure distribution detection during grasping.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: The present invention first discloses a flexible capacitive pressure sensing array adapted to a bionic dexterous hand, comprising an upper flexible substrate, an intermediate dielectric layer and a lower flexible substrate stacked together, wherein the intermediate dielectric layer is sandwiched between the upper flexible substrate and the lower flexible substrate.

[0008] The upper flexible substrate has M longitudinally extending electrodes printed on its inner surface facing the middle dielectric layer, and N circular sensing electrodes (as driving electrodes) are arranged corresponding to each longitudinal electrode along its length. The lower flexible substrate has N transversely extending electrodes printed on its inner surface facing the middle dielectric layer, and M circular sensing electrodes (as sensing electrodes) are arranged corresponding to each transverse electrode along its length. The electrode material is stretchable silver paste or silver-copper paste.

[0009] The vertical and horizontal electrodes are arranged perpendicularly and intersecting each other. Each circular sensing electrode on the vertical electrode is directly opposite to each circular sensing electrode on the horizontal electrode. Each directly opposite intersection position forms an independent capacitive sensing unit, and the whole constitutes an M×N array sensing area.

[0010] The overall shape of the sensor array is a bionic contour that is completely adapted to the palm and five fingers of the bionic dexterous hand. The non-sensing area is provided with a sealing edge and a reserved flexible base film for assembly and fixation with the dexterous hand. The reserved flexible base film can be fixedly connected to the mounting surface of the dexterous hand by hot pressing or adhesive bonding.

[0011] The vertical and horizontal electrodes adopt a non-uniform biomimetic layout, and the density distribution is positively correlated with the tactile sensitivity requirements of each operating area of ​​the dexterous hand; among them, the electrode spacing in the finger area is smaller than that in the palm area, the diameter of the circular sensing electrode in the finger area is smaller than that in the palm area, and the density of the capacitive sensing unit in the finger area is greater than that in the palm area.

[0012] All vertical electrodes extend continuously from the fingertip area to the wrist area. The horizontal electrodes in the palm area are arranged in a continuous arc; the horizontal electrodes in the finger area are arranged along the fingertips and form a continuous loop through the finger gaps. All horizontal electrode lines eventually converge to the wrist area.

[0013] The wiring of the longitudinal electrode uses a curved path that bends back and forth in the bending area corresponding to the finger joint to release bending stress.

[0014] All electrode lines converge at the corresponding position on the wrist and mate with the FPC connector. Specifically, all vertical and horizontal electrodes form an N / 2+M+N / 2 line convergence structure in the corresponding area of ​​the wrist, that is, the horizontal electrode lines are divided into two groups and arranged on both sides of the vertical electrode lines. This convergence structure matches the M+N pin FPC connector.

[0015] As a preferred embodiment, the vertical electrodes are arranged in a partitioned biomimetic configuration: X vertical electrodes are arranged in the corresponding areas of the little finger, ring finger, middle finger, and index finger, and Y vertical electrodes are arranged in the corresponding area of ​​the thumb, where X ≤ Y, to accommodate the wider biomimetic structure of the thumb and achieve uniform coverage of the hand sensing area. More preferably, X is 1 to 10, and Y is 1 to 10.

[0016] As a preferred embodiment, the horizontal electrodes adopt a partitioned biomimetic layout: F1 horizontal electrodes are placed in the corresponding areas of the first fingertips of each of the five fingers; F2 and F3 horizontal electrodes are placed in the corresponding areas of the second and third fingertips of the index, middle, ring, and little fingers, respectively; F2+F3 horizontal electrodes are placed in the corresponding area of ​​the second fingertips of the thumb; and the remaining horizontal electrodes are placed in the palm area, with F2 and F3 both being smaller than F1, giving the first fingertips of the fingers a higher sensing density to meet the needs of fine fingertip perception. Specifically, in the horizontal electrodes corresponding to the palm area, the horizontal electrodes in the upper half of the palm area are in the shape of an upwardly convex continuous arc, and adjacent horizontal electrodes are evenly spaced; the horizontal electrodes in the lower half of the palm area are continuous lines extending from the hypothenar eminence to the thenar eminence, and their distribution exhibits a "dense at the edges and sparse at the center" characteristic, that is, the spacing between horizontal electrodes in the center of the palm area is greater than the spacing between horizontal electrodes in the edge areas. More preferably, F1 is 1-10, and F2+F3 is 2-20.

[0017] As a preferred embodiment: the spacing between adjacent vertical and horizontal electrodes in the finger region is 1mm to 5mm, and the spacing between adjacent vertical and horizontal electrodes in the palm region is 2mm to 10mm; the diameter of the circular sensing electrode in the finger region is 1mm to 3mm, and the diameter of the circular sensing electrode in the palm region is 2mm to 8mm; the overall capacitive sensing unit density of the sensing array is 1 to 64 points / cm². 2 .

[0018] As a preferred embodiment: the line width of the wiring area of ​​the longitudinal and transverse electrodes, excluding the circular sensing electrodes, is 100μm to 600μm; auxiliary wiring is arranged along the periphery of the biomimetic contour of the sensing array, and the auxiliary wiring is an extension structure of the longitudinal and transverse electrode lines, with a spacing of 0.4mm to 1mm between adjacent auxiliary wirings.

[0019] As a preferred embodiment, the bending radius of the curved path that bends back and forth at the finger joint is 0.5mm to 3mm, and the bending arc angle of the curved path is 90° to 270°.

[0020] As a preferred embodiment: the upper flexible substrate and the lower flexible substrate are made of the same flexible polymer film material, selected from any one of polyurethane film, PDMS film, PE film, and polyimide film, with a thickness of 10–100 μm; the intermediate dielectric layer is an ion gel-polyurethane composite dielectric layer or a piezoresistive composite elastomer layer, with a thickness of 100 μm–2000 μm. The upper flexible substrate, intermediate dielectric layer, and lower flexible substrate are vacuum thermo-sealed at the sealing edge to form an integrated structure.

[0021] As a preferred embodiment, both sides of the intermediate dielectric layer are formed with microstructures; the microstructures are selected from any one of hemispherical, pyramidal, or randomly protruding porous structures, and the microstructures meet the following size parameters: microstructure height 10μm~20μm, microstructure feature diameter 1μm~20μm, and spacing between adjacent microstructures 1μm~10μm.

[0022] This invention further discloses a method for fabricating a flexible capacitive pressure sensing array adapted to a biomimetic dexterous hand, comprising the following steps: 1) Substrate pretreatment: The flexible substrate film is cut to the preset biomimetic contour size and surface pretreatment is performed by plasma cleaning or ethanol wiping to remove impurities from the film surface.

[0023] 2) Electrode printing: A microelectronic circuit printer is used to print vertical electrodes, horizontal electrodes and corresponding circular sensing electrodes on the surfaces of the upper and lower flexible substrate films respectively; the printing process parameters are: printing speed 1~10mm / s, curing temperature 50℃, and curing time 3h.

[0024] 3) Preparation of intermediate dielectric layer: Ionic liquid or other conductive material is mixed with polyurethane solution, stirred evenly and then rolled into a film. Microstructure is then hot-pressed onto the surface of the film to obtain ion gel-polyurethane composite dielectric layer or piezoresistive composite elastomer layer.

[0025] 4) Layer alignment: The upper flexible substrate, the middle dielectric layer and the lower flexible substrate are precisely aligned to ensure that the upper and lower circular sensing electrodes are aligned and matched one by one, and the alignment error is controlled within the range of 0.1 to 0.2 mm.

[0026] 5) Integrated packaging: The three-layer structure after alignment is integrated and packaged using vacuum hot pressing process to form a sealed edge. The process parameters are: hot pressing temperature 100℃, molding pressure 3MPa, holding pressure time 3min, and vacuum degree -0.09MPa.

[0027] 6) Bionic Cutting and Fixing: Laser cutting is performed according to the bionic contour, and a flexible substrate film for assembly and fixing is reserved in the non-sensor areas to complete the processing and assembly of the sensor array. It can be assembled and fixed to the bionic dexterous hand by hot pressing or adhesive bonding.

[0028] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. **Zoned Electrode Layout for Superior Tactile Sensing Performance:** This invention employs a biomimetic differentiated density layout. High-density electrodes are deployed in the fingers, especially the fingertips, effectively improving the resolution of recognizing minute contacts and surface textures. Low-density electrodes are deployed in the palm area, adapting to the gripping of large objects and accurately monitoring overall pressure distribution. This design precisely matches the sensing layout with tactile usage requirements, significantly enhancing the overall sensing capabilities of the biomimetic dexterous hand.

[0029] 2. Special circuit design in bending areas enhances circuit reliability and durability: The curved routing in areas with repeated bending, such as joints, effectively releases the mechanical stress generated by bending, improves the circuit's fatigue resistance, prevents circuit breakage due to repeated deformation, and significantly extends the service life and operational stability of the sensor array.

[0030] 3. Bionic overall contour, good assembly and motion compatibility: The shape of the sensor array is adapted to the contour of the dexterous hand's palm and fingers, and can be seamlessly integrated with the body, making integration and installation convenient; at the same time, it will not interfere with hand movements, ensuring the dexterous hand's flexibility.

[0031] 4. Composite dielectric layer surface microstructure enhances sensing performance: The combination of ion gel-polyurethane composite dielectric layer and surface microstructure can improve the sensor's pressure response sensitivity, reduce detection hysteresis, and improve the linearity of pressure signal acquisition.

[0032] 5. Simple structure, easy for large-scale preparation: This invention uses a polyurethane film as a substrate, combined with an ion gel-polyurethane composite material as the dielectric layer. The electrodes can be processed and shaped using mature processes such as printing and microcircuit printing. The overall structure is simple, the preparation process is reliable, production costs can be effectively controlled, and it is suitable for mass production. Attached Figure Description

[0033] Figure 1 The overall biomimetic wiring diagram of the flexible capacitive pressure sensing array adapted to the biomimetic dexterous hand of this invention shows the integrated shape of the palm and five fingers and the cross-arrangement structure of the electrodes in the whole area. Figure 2 This is a schematic diagram of the individual distribution of the vertical electrodes of the present invention, showing the arc-shaped routing of the horizontal electrodes in each fingertip and palm area; Figure 3 This is a schematic diagram of the horizontal electrode distribution of the present invention, showing the overall arrangement of the vertical electrode extending from the fingertip to the wrist; Figure 4 for Figure 2 A magnified view of the curved path that bends back and forth at the middle finger joint; Figure 5 for Figure 1 A magnified view of the distribution of electrodes and sensing units at the base of the middle finger; Figure 6 for Figure 1 A magnified view of the distribution of electrodes and sensing units in the middle palm area; Figure 7 for Figure 1 Enlarged view of the lead-out portion of the mid-wrist electrode circuit; Figure 8 This is a schematic cross-sectional view of the three-layer stacked structure of the sensor array of the present invention; Figure 9 The dynamic response characteristic test curve of the flexible capacitive pressure sensing array of the present invention shows the trend of the capacitance signal changing over time during finger pressing, intuitively demonstrating the sensor's fast response performance of 30 ms. Figure 10 The pressure sensitivity characteristic curve of the flexible capacitive pressure sensing array of the present invention shows the variation of the relative capacitance change ΔC / C0 with the applied pressure over the entire pressure range, and marks the sensitivity values ​​corresponding to different pressure ranges.

[0034] Reference numerals: 1-Upper flexible substrate; 2-Lower flexible substrate; 3-Intermediate dielectric layer; 4-Vertical electrode; 5-Horizontal electrode; 6-Circular sensing electrode; 7-Back-and-forth curved trace; 8-Microstructure; 9-Auxiliary trace; 10-Sealing edge; 11-Reserved flexible substrate film; 12-FPC interface. Detailed Implementation

[0035] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. These embodiments are only used to explain the invention and do not constitute a limitation on the invention.

[0036] This invention discloses a flexible capacitive pressure sensing array adapted to a bionic dexterous hand and its fabrication method. The core of the invention lies in using a flexible substrate with a microstructure dielectric layer, and through a non-uniform bionic electrode layout, joint anti-bending curve circuit, and wrist integrated FPC lead-out structure, to achieve differentiated high-precision tactile perception of the entire palm and finger joints of the bionic dexterous hand. At the same time, the invention employs a printing + vacuum hot pressing integrated process to achieve large-scale and highly consistent fabrication of the sensor.

[0037] Combination Figures 1 to 8 The flexible capacitive pressure sensing array of the present invention includes an upper flexible substrate 1, an intermediate dielectric layer 3 and a lower flexible substrate 2 stacked together, wherein the intermediate dielectric layer 3 is sandwiched between the upper flexible substrate 1 and the lower flexible substrate 2.

[0038] M longitudinal electrodes 4 are printed on the inner surface of the upper flexible substrate 1 facing the middle dielectric layer 3. Each longitudinal electrode 4 has N circular sensing electrodes 6 arranged along its length. The longitudinal electrodes 4 are driving electrodes used to input high-frequency excitation electrical signals. N transverse electrodes 5 are printed on the inner surface of the lower flexible substrate 2 facing the middle dielectric layer 3. Each transverse electrode 5 has M circular sensing electrodes 6 arranged along its length. The transverse electrodes 5 are sensing electrodes used to collect capacitance change feedback signals. The electrode material is stretchable silver paste or silver-copper paste.

[0039] The vertical electrode 4 and the horizontal electrode 5 are arranged perpendicularly and intersecting each other. The circular sensing electrode 6 on the vertical electrode 4 and the circular sensing electrode 6 on the horizontal electrode 5 are matched one-to-one. Each intersection position forms an independent capacitive sensing unit, and the whole constitutes an M×N array sensing area.

[0040] The overall shape of the sensor array is a biomimetic contour that fits the palm and five fingers of a biomimetic dexterous hand. The non-sensing area retains a sealed edge 10 and a reserved flexible base film 11 for assembly and fixation. The reserved flexible base film 11 can be fixedly connected to the mounting surface of the dexterous hand by hot pressing or adhesive bonding.

[0041] The vertical electrode 4 and horizontal electrode 5 adopt a non-uniform biomimetic layout. The electrode density is positively correlated with the tactile sensitivity requirements of each area of ​​the dexterous hand: the electrode spacing in the finger area is smaller than that in the palm area, the diameter of the circular sensing electrode 6 in the finger area is smaller than that in the palm area, and the density of capacitive sensing units in the finger area is greater than that in the palm area.

[0042] All the longitudinal electrodes 4 extend continuously from the fingertips to the wrist area; the transverse electrodes 5 in the palm area are arranged in a continuous arc shape, and the transverse electrodes 5 in the finger area are arranged along the fingertips and run through the finger gaps to form a continuous loop. All the transverse electrode 5 lines eventually converge to the wrist area.

[0043] The longitudinal electrode 4 at the corresponding position of the finger joint is provided with a curved trace 7 that bends back and forth to release the mechanical stress generated by repeated bending.

[0044] All electrode lines converge at the wrist, and the convergence point serves as the FPC interface to connect to the FPC connector; the horizontal electrode 5 lines are evenly divided into two groups and arranged on both sides of the vertical electrode 4, forming an N / 2+M+N / 2 symmetrical convergence structure, which is compatible with the M+N pin flip-top type FPC connector. The connector can be a 0.5mm or 1mm pitch flip-top type, and the line spacing is consistent with the pin spacing of the FPC connector.

[0045] The vertical electrodes are arranged in four biomimetic zones: X vertical electrodes are arranged in each of the little finger, ring finger, middle finger and index finger areas, and Y vertical electrodes are arranged in the thumb area, where X≤Y, to adapt to the wider biomimetic size of the thumb and achieve uniform coverage of the whole area.

[0046] The transverse electrodes are arranged in a five-zone biomimetic configuration: F1 transverse electrodes are placed on the first fingertip of each of the five fingers; F2 and F3 transverse electrodes are placed on the second and third fingertip of the index, middle, ring, and little fingers, respectively; F2+F3 transverse electrodes are placed on the second fingertip of the thumb; and the remaining transverse electrodes are arranged in the palm area, with F2 and F3 being smaller than F1 to enhance the sensory density of the fingertips. Specifically, the transverse electrodes in the upper half of the palm are arranged in a continuous, upward-convex arc shape to fit the curvature of the palm; the transverse electrodes in the lower half of the palm extend from the hypothenar eminence to the thenar eminence, exhibiting a biomimetic distribution characteristic of denser edges and sparser center, matching the force distribution pattern of human hand grip.

[0047] The spacing between adjacent vertical electrodes 4 and horizontal electrodes 5 in the finger area is 1mm to 5mm, and 2mm to 10mm in the palm area; the diameter of the circular sensing electrode 6 in the finger area is 1mm to 3mm, and 2mm to 8mm in the palm area; the overall sensing unit density is 1 to 64 points / cm². 2 .

[0048] In addition to the circular sensing electrode 6, the line widths of the longitudinal electrode 4 and the transverse electrode 5 are 100μm to 600μm; auxiliary lines 9 are set along the periphery of the biomimetic contour, with a spacing of 0.4mm to 1mm between adjacent auxiliary lines 9.

[0049] The parameters for the curved trace 7 with back-and-forth bends are: bending radius 0.5mm~3mm, bending arc angle 90°~270°.

[0050] The upper flexible substrate 1 and the lower flexible substrate 2 are the same type of flexible polymer film, which can be polyurethane film, PDMS film, PE film, or polyimide film, with a thickness of 10 to 100 μm; the middle dielectric layer 3 is an ion gel-polyurethane composite dielectric layer or a piezoresistive composite elastomer layer, with a thickness of 100 μm to 2000 μm; the three-layer structure is integrally encapsulated at the sealing edge 10 by vacuum hot pressing.

[0051] Microstructures 8 are formed on both sides of the intermediate dielectric layer 3. The microstructures 8 can be hemispherical, pyramidal, or have random protruding holes. The height of the microstructure is 10μm to 20μm, the characteristic diameter is 1μm to 20μm, and the spacing between adjacent microstructures is 1μm to 10μm.

[0052] The invention also includes a corresponding preparation process, the steps of which are as follows: 1) Substrate pretreatment: The flexible substrate is cut into a biomimetic contour and surface impurities are removed by plasma cleaning or ethanol wiping; 2) Electrode printing: A microelectronic circuit printer is used to print the vertical electrode 4, the horizontal electrode 5 and the circular sensing electrode 6 on the surface of the upper flexible substrate film and the lower flexible substrate film respectively. The printing speed is 1-10 mm / s and the curing time is 50℃ for 3 hours. 3) Preparation of intermediate dielectric layer 3: Ionic liquid or other conductive material is mixed and stirred with polyurethane solution, and then rolled into a film and hot-pressed to replicate microstructure 8 to obtain ion gel-polyurethane composite dielectric layer or piezoresistive composite elastomer layer. 4) Layer alignment: The upper flexible substrate 1, the middle dielectric layer 3, and the lower flexible substrate 2 are precisely aligned to ensure that the circular sensing electrodes 6 correspond one-to-one, with an alignment error of 0.1 to 0.2 mm. 5) Integrated packaging: Vacuum hot pressing to form a sealed edge, hot pressing temperature 100℃, pressure 3MPa, holding pressure for 3min, vacuum degree -0.09MPa; 6) Bionic cutting and fixing: Laser cutting is performed according to the bionic contour, and a sealing edge 10 and a reserved flexible base film 11 for assembly and fixing are reserved in the non-sensing area to complete the processing and assembly of the sensor array.

[0053] Example 1 This embodiment provides a flexible capacitive pressure sensing array, based on the aforementioned general basic structure, with specific material, size, and electrode layout parameters as follows: Substrate material: The upper flexible substrate 1 and the lower flexible substrate 2 are made of BASF 1180A polyurethane film with a fixed thickness of 100μm, which has high flexibility, high stretchability and repeated bending resistance.

[0054] Number of electrodes: 4 longitudinal electrodes, a total of 16 electrodes, 3 each for the little finger, ring finger, middle finger, and index finger, and 4 for the thumb; 5 transverse electrodes, a total of 16 electrodes, 5 for the first fingertip of each of the five fingers, 2 for the second and third fingertip of each finger, 4 for the second fingertip of the thumb, and 7 for the palm.

[0055] Electrode spacing and sensing unit size: Circular sensing electrode 6 in the finger area has a diameter of 1.5mm and an electrode spacing of 1mm–5mm; circular sensing electrode 6 in the palm area has a diameter of 2.5mm and an electrode spacing of 2mm–10mm. Corresponding sensing density: 9 points / cm² for fingertips. 2 6 points / cm on the fingertip 2 4 points / cm along the edge of the palm 2 2 points in the center of the palm / cm 2 It perfectly meets the needs of bionic tactile perception, enabling high-precision and subtle perception at the fingertips and large-scale pressure monitoring of the palm.

[0056] Wiring parameters: Electrode trace width 200μm, peripheral auxiliary traces 9 spacing 0.5mm; curved traces 7 with back-and-forth bends have a bending radius of 0.5mm and a bending arc angle of 180°, effectively releasing mechanical stress from bending and preventing circuit breakage and signal drift caused by repeated deformation. The wrist auxiliary traces 9 adopt an 8+16+8 symmetrical arrangement, compatible with 32-pin, 1mm pitch flip-top FPC connectors. The trace spacing and connector pins are precisely matched, enabling rapid docking of the sensor with external detection circuits.

[0057] Intermediate dielectric layer: This is an ion gel-polyurethane composite dielectric layer with an overall thickness of 100 μm. It is prepared by mixing lithium bis(trifluoromethanesulfonate)imide and polyurethane at a mass ratio of 7%:93%. Hemispherical microstructures with a diameter of 15 μm are etched onto the surface of the dielectric layer using 1000-grit sandpaper. The uniform distribution of these microstructures on the dielectric layer surface effectively improves the sensor's pressure response sensitivity and linearity, while reducing hysteresis.

[0058] Electrode paste: BroadCON-FS750 flexible stretchable silver paste is used for printing and molding, which is suitable for the deformation requirements of flexible substrates.

[0059] This embodiment uses a microelectronic direct-write printing + vacuum thermopressing integrated process to fabricate the above-mentioned biomimetic flexible sensor array. The specific steps are as follows: (1) Substrate pretreatment: Select a 100μm thick BASF 1180A polyurethane film, pre-cut it into a biomimetic contour blank that fits the dexterous hand, wipe the surface with anhydrous ethanol, and then dry it at low temperature to remove dust, oil and impurities from the film surface to ensure the adhesion of the electrode printing.

[0060] (2) Electrode printing: A BroadTeko DW200 microelectronic printer was used, with BroadCON-FS750 flexible stretchable silver paste as the electrode material, to print longitudinal electrodes 4 and transverse electrodes 5 on the pretreated surfaces of the upper and lower polyurethane films, respectively. The printing process parameters were set as follows: printing speed 3 mm / s, electrode line width precisely controlled at 200 μm, and after printing, the electrodes were placed in a constant temperature environment of 50℃ for 3 hours to ensure the conductivity stability of the electrodes and the adhesion of the film.

[0061] (3) Preparation of intermediate dielectric layer: Lithium bis(trifluoromethanesulfonate)imide and polyurethane are mixed in DMF at a mass ratio of 7%:93% and stirred at a speed of 500r / min until completely uniform. The film is uniformly formed by roller coating process. Then, a hemispherical microstructure is formed by hot pressing and transfer using 1000-grit sandpaper as a template. Finally, a composite dielectric layer with a thickness of 100μm and a regular hemispherical microstructure 8 on the surface is obtained.

[0062] (4) Layer alignment: The printed upper flexible substrate 1, the middle dielectric layer 3 with microstructure 8 and the lower flexible substrate 2 are stacked in sequence. The three-layer structure is calibrated by a precision alignment device. The alignment error is strictly controlled within 0.2mm to ensure that the cross accuracy of the vertical electrode 4 and the horizontal electrode 5 is consistent with that of the circular sensing electrode 6.

[0063] (5) Integrated packaging: The aligned stacked structure is placed in a vacuum hot press equipment and the process parameters are set as follows: vacuum degree -0.09MPa, hot press temperature 100℃, molding pressure 3MPa, and holding time 3min. Through vacuum hot press, the three-layer structure of upper flexible substrate 1, middle dielectric layer 3 and lower flexible substrate 2 is seamlessly composited and integrated, eliminating delamination and bubble defects.

[0064] (6) Bionic cutting and fixing: Laser precision cutting is performed according to the preset bionic contour of the dexterous hand palm + five fingers, retaining the sealing edge 10 and the reserved flexible base film 11 for assembly and fixing, thus completing the preparation and assembly of the sensor array; finally, the sensor array is fixed to the surface of the bionic dexterous hand by hot pressing or flexible adhesive.

[0065] The capacitive pressure sensing array prepared in this embodiment underwent full-range performance testing, such as... Figures 9-10 As shown: Pressure detection range: 0–1000 kPa; sensitivity: up to 11.4 kPa. -1 The pressure response time is 30ms; after 100,000 repeated bending fatigue tests of the joint, the longitudinal electrode 4 and transverse electrode 5 circuits showed no breakage, the sensing signal did not drift, and there was no significant performance degradation.

[0066] Example 2 This embodiment provides a capacitive pressure sensing array, whose structure and fabrication process are basically the same as those in Embodiment 1. The only difference is that the intermediate dielectric layer is replaced by a piezoresistive composite elastomer layer instead of an ion gel-polyurethane composite dielectric layer, specifically a multi-walled carbon nanotube-modified polyurethane piezoresistive elastomer layer. Accordingly, the fabrication process of the intermediate dielectric layer is as follows: multi-walled carbon nanotubes and polyurethane are mixed in DMF at a mass ratio of 3%:97%, and then the intermediate dielectric layer is prepared using the same method as in Embodiment 1. This ratio allows the composite elastomer to possess a stable piezoresistive effect, and the density of the internal conductive network undergoes a reversible change under stress deformation, enabling accurate acquisition of pressure signals.

[0067] The above are merely exemplary embodiments of the present invention and are not intended to limit the present invention. Any equivalent substitutions, modifications, variations or improvements made within the spirit and principles of the present invention should be covered within the protection scope of the present invention.

Claims

1. A flexible capacitive pressure sensing array adapted to a bionic dexterous hand, characterized in that, It includes an upper flexible substrate, an intermediate dielectric layer, and a lower flexible substrate stacked together; the intermediate dielectric layer is sandwiched between the upper flexible substrate and the lower flexible substrate; The upper flexible substrate has M longitudinal electrodes printed on its inner surface facing the middle dielectric layer, and N circular sensing electrodes are arranged in the length direction of each longitudinal electrode; the lower flexible substrate has N transverse electrodes printed on its inner surface facing the middle dielectric layer, and M circular sensing electrodes are arranged in the length direction of each transverse electrode. The vertical electrodes and the horizontal electrodes are arranged perpendicularly and intersecting each other. Each circular sensing electrode on the vertical electrode is directly matched with each circular sensing electrode on the horizontal electrode. Each directly matched intersection position forms an independent capacitive sensing unit, and the whole constitutes an M×N array sensing area. The overall shape of the sensor array is a biomimetic contour that fits the palm and five fingers of the biomimetic dexterous hand. The non-sensing area of ​​the sensor array is provided with a sealing edge and a reserved flexible substrate film for assembly and fixation with the dexterous hand. The vertical and horizontal electrodes adopt a non-uniform biomimetic layout. The electrode spacing in the finger area is smaller than that in the palm area. The diameter of the circular sensing electrode in the finger area is smaller than that in the palm area. The density of the capacitive sensing unit in the finger area is greater than that in the palm area. All vertical electrodes are laid out continuously from the fingertip area to the wrist area; the horizontal electrodes in the palm area are laid out in a continuous arc; the horizontal electrodes in the finger area are laid out along the fingertip and form a continuous loop through the finger gaps, and all horizontal electrode lines eventually converge to the wrist area. The wiring of the longitudinal electrode adopts a curved path that bends back and forth in the bending area corresponding to the finger joint. All electrode lines converge at the corresponding position on the wrist and connect to the FPC connector.

2. The flexible capacitive pressure sensing array adapted to a bionic dexterous hand according to claim 1, characterized in that, The longitudinal electrodes are arranged in a zoned biomimetic manner: X longitudinal electrodes are arranged in the corresponding areas of the little finger, ring finger, middle finger, and index finger, and Y longitudinal electrodes are arranged in the corresponding area of ​​the thumb, where X≤Y.

3. The flexible capacitive pressure sensing array adapted to a bionic dexterous hand according to claim 1, characterized in that, The horizontal electrodes are arranged in a partitioned biomimetic manner: F1 horizontal electrodes are arranged in the corresponding areas of the first fingertips of the five fingers; F2 and F3 horizontal electrodes are arranged in the corresponding areas of the second and third fingertips of the index, middle, ring, and little fingers, respectively; F2+F3 horizontal electrodes are arranged in the corresponding area of ​​the second fingertips of the thumb; and the remaining horizontal electrodes are arranged in the palm area, with F2 and F3 both being less than F1.

4. The flexible capacitive pressure sensing array adapted to a bionic dexterous hand according to claim 1, characterized in that: The linewidth of the longitudinal and transverse electrodes is 100μm to 600μm; Auxiliary traces are arranged around the biomimetic contour of the sensor array. The auxiliary traces are extensions of the longitudinal and transverse electrode lines, and the spacing between adjacent auxiliary traces is 0.4 mm to 1 mm.

5. A flexible capacitive pressure sensing array adapted to a bionic dexterous hand according to claim 1, characterized in that: The bending radius of the curved path that bends back and forth at the finger joint is 0.5mm to 3mm, and the bending arc angle of the curved path is 90° to 270°.

6. A flexible capacitive pressure sensing array adapted to a bionic dexterous hand according to claim 1, characterized in that: The upper flexible substrate and the lower flexible substrate are made of the same flexible polymer film material, which is selected from any one of polyurethane film, PDMS film, PE film, and polyimide film; the intermediate dielectric layer is an ion gel-polyurethane composite dielectric layer or a piezoresistive composite elastomer layer.

7. A flexible capacitive pressure sensing array adapted to a bionic dexterous hand according to claim 1, characterized in that: The spacing between adjacent vertical and horizontal electrodes in the finger region is 1mm to 5mm, while the spacing between adjacent vertical and horizontal electrodes in the palm region is 2mm to 10mm. The diameter of the circular sensing electrode in the finger region is 1mm to 3mm, and the diameter of the circular sensing electrode in the palm region is 2mm to 8mm. The overall capacitive sensing unit density of the sensing array is 1 to 64 points / cm². 2 .

8. A flexible capacitive pressure sensing array adapted to a bionic dexterous hand according to claim 1, characterized in that, Both sides of the intermediate dielectric layer are formed with microstructures, which are selected from hemispherical, pyramidal, or random porous structures.

9. A method for fabricating a flexible capacitive pressure sensing array adapted to a bionic dexterous hand as described in any one of claims 1 to 8, characterized in that, Includes the following steps: (1) Surface pretreatment of the flexible substrate; (2) Print longitudinal electrodes, transverse electrodes and corresponding circular sensing electrodes on the surfaces of the pretreated upper and lower flexible substrates, respectively. (3) Prepare the intermediate dielectric layer; (4) The upper flexible substrate, the middle dielectric layer and the lower flexible substrate are precisely aligned to ensure that the upper and lower circular sensing electrodes are aligned and matched one by one. (5) The three-layer structure after alignment is encapsulated in an integrated manner using a vacuum hot pressing process to form a sealed edge; (6) Laser cutting is performed according to the biomimetic contour, and a flexible substrate film for assembly and fixation is reserved in the non-sensing area to complete the processing and assembly of the sensor array.

10. The method for fabricating a flexible capacitive pressure sensing array adapted to a biomimetic dexterous hand according to claim 9, characterized in that: Step (2) The electrode is printed using microelectronic direct writing printing process. The process parameters are set as follows: printing speed 1~10mm / s, curing temperature 40~70℃, curing time 2~12h; Step (5) The parameters of the vacuum hot pressing encapsulation process are set as follows: hot pressing temperature 100℃, forming pressure 2~5MPa, holding time 2~10min, vacuum degree -1~-0.05MPa.

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