Dexterous hand electronic skin manufacturing method, dexterous hand electronic skin and printing equipment

Abstract

The invention relates to the technical field of electronic skin, and discloses a dexterous hand electronic skin manufacturing method, dexterous hand electronic skin and printing device.The dexterous hand electronic skin manufacturing method comprises the steps that conductive printing ink is prepared and added into the printing device; the printing equipment is fixed to a three-axis displacement platform and located above a printing platform; the three-axis displacement platform and the printing equipment are started, and a sensor array model is formed through printing in an interface range limiting mode; the sensor array model is solidified and packaged, and manufacturing of the electronic skin of the dexterous hand is completed. The sensor array model is printed in a 3D printing and interface confinement mode, compared with a traditional technology, complex technical combinations such as deposition, sputtering, photoetching or laser processing are not needed, grooving is also not needed, the technological process is simplified, the production cost is effectively reduced, meanwhile, rapid printing can be achieved by means of an automatic three-axis displacement platform and printing equipment, and the production efficiency is improved. And the production efficiency is greatly improved.

Description

Technical Field

[0001] This invention relates to the field of electronic skin technology, specifically to a method for manufacturing dexterous hand electronic skin, dexterous hand electronic skin, and printing equipment. Background Technology

[0002] With the rapid development of robotics, medical rehabilitation, and smart wearables, the demand for flexible sensors capable of accurately perceiving the external environment and efficiently interacting with the human body or objects is becoming increasingly urgent. In robotic systems, the dexterous hand, as a core component enabling fine manipulation, directly determines the robot's performance in complex tasks and is crucial for expanding the application of robots in industrial assembly, medical surgery, and home services. Electronic skin, as a core technology endowing the dexterous hand with tactile sensing capabilities, can collect environmental information such as pressure, temperature, and texture in real time, enabling natural interaction between the robot and its external environment. It has become a current research hotspot and a key technological breakthrough in the field of robotics.

[0003] Traditional rigid sensors face significant limitations in adapting to curved or soft surfaces and dynamic interactive scenarios due to their large size and poor flexibility. When applied to non-planar carriers such as robotic dexterity hands and human skin, rigid sensors suffer from insufficient fit and signal distortion, making it difficult to meet the sensing needs of complex surfaces. Against this backdrop, flexible sensors have emerged and become a research hotspot in the field of sensing technology. Triboelectric flexible sensing technology is based on triboelectricity and electrostatic coupling effects, utilizing the charge transfer phenomenon generated during the contact-separation process of two different materials. By optimizing the sensor structure design and material combination, it can achieve highly sensitive responses to external stimuli such as pressure, strain, and vibration. This technology has advantages such as self-powered operation, simple structure, and low cost, showing great application potential in wearable devices, human-computer interaction, and intelligent robots.

[0004] Currently, triboelectric flexible sensors are generally made using a combination of technologies such as deposition, sputtering, photolithography, or laser processing. Regularized sensing units and connecting leads are constructed by slotting or stacking layers, which results in high costs and complicated processes, reducing production efficiency.

[0005] Therefore, existing technologies still need to be improved and developed. Summary of the Invention

[0006] In view of the shortcomings of the prior art, the purpose of this invention is to provide a method for manufacturing dexterous hand electronic skin, dexterous hand electronic skin and printing equipment, in order to solve the problems of high manufacturing cost and complicated process of triboelectric flexible sensor in the prior art.

[0007] The technical solution adopted by this invention to solve the technical problem is as follows:

[0008] The manufacturing method of dexterous hand electronic skin includes:

[0009] Prepare conductive printing ink and add it into the printing equipment;

[0010] The printing device is fixed on a three-axis displacement platform and positioned above the printing platform;

[0011] The triaxial displacement platform and the printing device are started, and a sensor array model is printed by interface confinement.

[0012] The sensor array model is solidified and packaged to complete the fabrication of the dexterous hand electronic skin.

[0013] Furthermore, the preparation of conductive printing ink and its addition into the printing equipment includes:

[0014] To produce an outer friction layer ink and an inner conductive layer ink.

[0015] Furthermore, the fabrication of the outer friction layer ink and the inner conductive layer ink includes:

[0016] Polydimethylsiloxane, polytetrafluoroethylene, and silica are mixed in a mass ratio of 9:2:1 and then centrifuged and degassed to form the outer friction layer ink.

[0017] Furthermore, the process of fabricating the outer friction layer ink and the inner conductive layer ink further includes:

[0018] Liquid metal alloy and polydimethylsiloxane are mixed at a mass ratio of 4:1, and then centrifuged and degassed. The lower layer precipitate is taken as the inner conductive layer ink.

[0019] Furthermore, the step of activating the triaxial displacement platform and the printing device to print a sensor array model through interface confinement includes:

[0020] The preset printing path, air pump output pressure, injection hydraulic pump extrusion rate, and the moving speed of the printing device;

[0021] Start the three-axis displacement platform, the printing equipment, the air pump, and the injection hydraulic pump;

[0022] The height, angle, and speed of the printing device are adjusted to apply interfacial pressure to the conductive printing ink, actively constraining the flow area of ​​the conductive printing ink and forming a multi-layer sensor array model.

[0023] Furthermore, the process of solidifying and encapsulating the sensor array model to complete the fabrication of the dexterous hand electronic skin includes:

[0024] The multi-layer sensor array model was placed in a vacuum drying oven for heating and curing.

[0025] The solidified sensor array model is removed, activated, and encapsulated to obtain the dexterous hand electronic skin.

[0026] Furthermore, the preparation of conductive printing ink and its addition into the printing device includes, prior to:

[0027] The substrate was ultrasonically cleaned using anhydrous ethanol.

[0028] The surface of the substrate is treated by spraying adhesive onto a 3D printing platform to form a substrate.

[0029] A dexterous hand electronic skin, based on the above-mentioned method for manufacturing a dexterous hand electronic skin, includes:

[0030] A multi-layer sensor array model is arranged in a stacked manner to form a dexterous hand electronic skin; each layer of the sensor array model includes multiple fiber strips, which are arranged at intervals; the fiber strips of two adjacent sensor array models are in a vertical state to form a cross-stacked state.

[0031] A printing apparatus for the above-mentioned method of manufacturing dexterous hand electronic skin, comprising:

[0032] An inner shaft body is mounted on the three-axis displacement platform; the inner shaft body has a first flow channel and a second flow channel inside, and the first flow channel and the second flow channel are respectively connected to an external feed pump;

[0033] An outer shaft head sleeve is disposed at the bottom of the inner shaft body; the outer shaft head sleeve cooperates with the first flow channel and the second flow channel to output two layers of printing ink arranged coaxially.

[0034] Furthermore, the first flow channel forms a first opening groove at the bottom of the inner shaft body, and a first pipe is provided at the bottom of the inner shaft body. The first pipe cooperates with the first flow channel and is coaxially arranged in the first opening groove. A third flow channel is provided inside the outer shaft head sleeve, and the first pipe is coaxially arranged in the third flow channel. Both the first pipe and the bottom wall of the outer shaft head sleeve are provided with an inclination angle.

[0035] Compared with the prior art, the beneficial effects of the present invention are:

[0036] In this invention, conductive printing ink is prepared and placed in a printing device, which is then fixed on a three-axis displacement platform. A sensor array model is printed using an interface confinement method, followed by curing and encapsulation. Compared to traditional technologies, this method eliminates the need for complex combinations of deposition, sputtering, photolithography, or laser processing techniques, as well as the need for grooving, simplifying the process and effectively reducing production costs. Furthermore, the automated three-axis displacement platform and printing device enable rapid printing, significantly improving production efficiency and providing a more efficient and economical solution for the manufacture of flexible sensors such as dexterous hand electronic skin. Attached Figure Description

[0037] Figure 1 This is a flowchart of the manufacturing method of the dexterous hand electronic skin of the present invention.

[0038] Figure 2 This is a flowchart illustrating the manufacturing process of the smart electronic skin of this invention.

[0039] Figure 3 This is a schematic diagram of the sensor array model structure of the present invention.

[0040] Figure 4 This is a schematic diagram of the fiber strip structure of the present invention.

[0041] Figure 5 This is a schematic diagram of the printing device structure of the present invention.

[0042] Figure 6 This is a schematic diagram of the main structure of the inner shaft of the present invention.

[0043] Figure 7 This is a schematic diagram of the outer shaft head sleeve structure of the present invention.

[0044] The numbers in the diagram represent: 1. Sensor array model; 2. Fiber strip; 4. Inner shaft body; 41. First flow channel; 42. Second flow channel; 43. First pipe; 44. Positioning guide rail; 5. Outer shaft head sleeve; 51. Third flow channel; 52. Inclination angle; 53. Positioning hole. Detailed Implementation

[0045] To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0046] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0047] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0048] In view of the shortcomings of the prior art, this embodiment provides a method for manufacturing dexterous hand electronic skin, dexterous hand electronic skin and printing equipment, which can be referred to as follows:

[0049] As attached Figure 1 and attached Figure 2 As shown, the method for manufacturing dexterous hand electronic skin includes the following steps:

[0050] Step S100: Prepare conductive printing ink and add it into the printing device.

[0051] In this embodiment, 3D printing involves printing ink onto a substrate and then waiting for it to cure. However, the ink used in this application is a specific ink that requires special preparation methods. The prepared conductive printing ink is then placed into a printing device, resulting in a printed structure that possesses the characteristics of a dexterous hand electronic skin.

[0052] In traditional 3D printing technology, conventional ink is usually printed directly onto a substrate. After printing, it is only necessary to wait for the ink to solidify under natural conditions or simple heating, light exposure and other conventional methods. The process is relatively simple, and the manufactured structure is often limited to basic physical form construction, which is difficult to meet the application scenarios with strict performance requirements such as dexterous hand electronic skin.

[0053] The ink used in this application is a specific functional ink, and its preparation process has strict and precise requirements. In terms of material selection, materials with excellent conductivity must be carefully chosen as core components, such as gallium, indium, tin, or mixtures of metals. These materials impart good conductivity to the ink, which is crucial for realizing the electrical signal conduction function of the electronic skin. Simultaneously, a polymer matrix with high flexibility and elasticity, such as polydimethylsiloxane (PDMS), must be added to ensure that the printed structure can adapt to complex movements such as bending and stretching of the dexterous hand, possessing good flexibility and mechanical properties. Furthermore, to optimize the ink's rheological properties, dispersion stability, and enhance its triboelectric effect, various functional additives can be added to meet the ink's characteristic requirements and the needs of the printed dexterous hand electronic skin.

[0054] In terms of the preparation process, the conductive material and the matrix material must first be thoroughly mixed in a specific solvent. This process usually requires the use of high-speed stirring, ultrasonic dispersion and other means to ensure that the conductive material is uniformly dispersed in the matrix and to avoid agglomeration that would affect the ink performance. Subsequently, according to the ink's usage requirements, the degree of solvent evaporation and the proportion of curing agent added are precisely controlled. Through processes such as vacuum degassing and gradient heating, air bubbles inside the ink are further removed to improve its uniformity and stability, thereby preparing a conductive printing ink that meets the requirements. The prepared conductive printing ink is then precisely injected into a specially designed printing device.

[0055] Specifically, in one implementation of this embodiment, step S100 includes the following steps:

[0056] Step S110: Prepare the outer friction layer ink and the inner conductive layer ink.

[0057] In this embodiment, the conductive printing ink includes an outer friction layer ink and an inner conductive layer ink.

[0058] The outer friction layer ink is the core component for realizing the triboelectric effect. When the electronic skin comes into contact with an external object and undergoes relative motion, these materials transfer charge through friction with the object's surface. The outer friction layer material captures or loses electrons, thus generating triboelectric charges on the surface. For example, when a robotic arm grasps an object, the amount and polarity of the charge generated by the friction between the outer friction layer and the object's surface can reflect information such as contact pressure, frictional force, and the material properties of the contacting object. Simultaneously, as the part of the electronic skin that directly contacts the external environment, the outer friction layer provides physical protection for the inner conductive layer and other internal structures. It can resist damage from external wear, scratches, and chemical corrosion, preventing external factors from damaging the inner conductive structure, extending the lifespan of the electronic skin, and ensuring its long-term stable operation.

[0059] The inner conductive layer ink can quickly and efficiently conduct the triboelectric charge generated by the outer friction layer, converting it into electrical signals and transmitting them to subsequent signal processing circuits. This ensures that the electrical signals do not experience significant attenuation or distortion during transmission, providing a reliable electrical basis for accurately sensing and analyzing external information. Simultaneously, the inner conductive layer ink not only performs its conductive function but also provides structural support for the entire printed structure. The combination of its internal conductive and matrix materials enhances the overall mechanical strength of the electronic skin, enabling it to withstand certain external forces while maintaining its shape and structural stability, thus better adapting to the operational needs of the robotic arm.

[0060] Specifically, in one implementation of this embodiment, step S110 includes the following steps:

[0061] In step S110-A, polydimethylsiloxane, polytetrafluoroethylene and silica are mixed in a mass ratio of 9:2:1 and centrifuged and degassed to form the outer friction layer ink.

[0062] In this embodiment, polydimethylsiloxane (PDMS) possesses beneficial flexibility and chemical stability, providing good mechanical support for the friction layer; polytetrafluoroethylene (PTFE) is located at the negative electrode in the triboelectric sequence, readily gaining electrons, and its addition can significantly enhance the charge trapping energy of the friction layer; silica can adjust the rheological properties of the ink and can form micro-protrusions on the surface of the friction layer, further enhancing the triboelectric effect.

[0063] PDMS provides flexibility, PTFE contributes high electron affinity, and silica enhances surface roughness and charge density. The three work together to achieve a balance between triboelectric and mechanical properties. At the same time, the hydroxyl groups of silica nanoparticles form weak chemical bonds with the fluorine atoms of PTFE, which inhibits the shedding of PTFE particles during friction and extends the service life of the friction layer.

[0064] Specifically, in one implementation of this embodiment, step S110 further includes the following steps:

[0065] In step S110-B, the liquid metal alloy and polydimethylsiloxane are mixed at a mass ratio of 4:1, and centrifuged and degassed. The lower precipitate is then taken as the inner conductive layer ink.

[0066] In this embodiment, a liquid metal alloy of gallium, indium, and tin with a melting point of approximately 16°C is used. The mass ratio of gallium, indium, and tin is 68.5:21.5:10, which makes mixing and preparation easier. Gallium also has good chemical stability and is not easily oxidized, effectively avoiding the problem of decreased conductivity due to oxidation. Indium has a large atomic radius and can act as a "buffer" in the alloy lattice, enhancing the alloy's flexibility and ductility. This allows the printed conductive layer to maintain a good conductive network structure even when subjected to bending, stretching, or other deformations, preventing signal interruption due to structural damage. Tin has good conductivity and a high electron mobility, which can synergistically work with gallium and indium to further improve the overall conductivity of the alloy, reduce the resistance of the conductive layer, and ensure fast and stable transmission of electrical signals.

[0067] This alloy ink has extremely low resistivity, enabling it to conduct electrical signals quickly and efficiently. Compared to traditional conductive inks, it can significantly reduce signal loss during transmission, ensuring that the weak electrical signals generated by the sensor array model 1 can be accurately transmitted to subsequent circuits.

[0068] The inner conductive layer ink also has the flexibility and extensibility of No. 0, which can closely fit the complex curved surface of the robot. When the robot performs large-scale movements such as bending and twisting, the conductive layer will not break or fall off, and will continue to maintain stable conductivity.

[0069] Furthermore, the alloy has moderate viscosity and surface tension in the liquid state, which can be well adapted to commonly used printing equipment (such as pneumatically driven nozzles). During the printing process, the extrusion is smooth and the lines are uniform. The shape and size of the printed pattern can be precisely controlled, enabling high-precision printing of sensor array model 1.

[0070] Specifically, in one implementation of this embodiment, the following steps are included before step S100:

[0071] Step S101: Ultrasonic cleaning of the substrate using anhydrous ethanol;

[0072] Step S102: The surface of the substrate is treated by spraying adhesive on the 3D printing platform to form a substrate.

[0073] In this embodiment, a flat glass plate / metal plate / plastic plate, etc., is used as a substrate. Anhydrous ethanol is used for ultrasonic cleaning for 1-3 minutes. The substrate surface is then treated with 3D printer platform adhesive spray for 1 minute to form the substrate.

[0074] Step S200: Fix the printing device on the three-axis displacement platform and position it above the printing platform.

[0075] During the printing process, the printing equipment needs to be coordinated with the three-axis displacement platform, and the printing equipment needs to be positioned above the printing platform.

[0076] This printing equipment works in conjunction with a high-precision three-axis displacement platform to achieve precise control over parameters such as ink printing position, printing thickness, and nozzle movement speed.

[0077] Step S300: Start the triaxial displacement platform and the printing device, and print a sensor array model by means of interface confinement.

[0078] During the printing process, innovative technologies such as interface confinement are used to print ink onto a substrate according to a pre-designed pattern and structure, forming a sensor array model with a specific shape and function. This special printing method and ink properties enable the final printed structure to not only possess excellent conductivity and flexibility, but also achieve highly sensitive responses to external stimuli such as pressure, strain, and vibration based on triboelectric flexible sensing technology. This perfectly meets the performance requirements of dexterous hand electronic skin, providing precise tactile perception and feedback functions, and significantly improving its operational flexibility and intelligent interaction capabilities in complex environments.

[0079] As attached Figure 2 As shown, a single-layer sensor array model can first be printed on the substrate using a printing device, as shown in the attached figure. Figure 2 As shown in (A); then the substrate is rotated 90 degrees, and a second sensor array model is printed again on the surface of the single-layer sensor array model using a printing device, so as to form a cross-stacked state, as shown in the attached figure. Figure 2 As shown in (B); then perform curing and encapsulation, and then select the required number of upper and lower fiber layers and apply uniform external force to activate, as shown in the attached diagram. Figure 2 As shown in (C), the external force is the squeezing force exerted by external equipment or external components on the internal fluid within the sensor array model.

[0080] Specifically, in one implementation of this embodiment, step S300 includes the following steps:

[0081] Step S310: Preset the printing path, air pump output pressure, injection hydraulic pump extrusion rate, and the moving speed of the printing device;

[0082] Step S320: Start the three-axis displacement platform, the printing equipment, the air pump, and the injection hydraulic pump;

[0083] Step S330: Adjust the height, angle, and speed of the printing device to apply interfacial pressure to the conductive printing ink, actively constrain the flow area of ​​the conductive printing ink, and form a multi-layer sensor array model.

[0084] Before printing begins, several key parameters need to be precisely preset to ensure the integrity of the printed sensor array model 1.

[0085] First, based on the structure of the template sensor array model 1, computer-aided design (such as CAD software) and computer-aided manufacturing (such as CAM software) software are used to generate three-dimensional printing path data, accurately plan the movement trajectory of the print head in the X, Y, and Z directions, and ensure the positional accuracy of each layer pattern and the alignment accuracy between layers.

[0086] Secondly, based on the rheological properties of different types of conductive printing inks (such as outer friction layer ink and inner conductive layer ink), the output air pressure of the air pump (usually 5.0-6.5MPa) and the extrusion rate of the injection hydraulic pump (0.015-0.03ml / min) are precisely set to ensure that the ink can be stably and continuously extruded from the printing needle, and that the extrusion amount matches the nozzle movement speed of the printing equipment; at the same time, the nozzle movement speed is maintained at 160-200mm / min.

[0087] Finally, based on the curing characteristics of the ink and the surface properties of the substrate material, the nozzle movement speed is set appropriately to ensure that the ink has enough time to spread and cure after being deposited on the substrate, while avoiding line breakage or uneven accumulation due to excessive speed.

[0088] The three-axis displacement platform allows for adjustment of the printing equipment height to achieve different printing layers and pattern requirements; it also controls the distance between the printing needle and the substrate to apply appropriate interfacial pressure; and it can adjust the angle of the print head as needed, such as when printing inclined or curved structures, to ensure that ink can be accurately deposited at the target location.

[0089] Specifically, in one implementation of this embodiment, step S310 includes the following steps:

[0090] Step S311: Preset the printing spacing and printing direction of the printing device.

[0091] In this embodiment, the preset printing path includes printing spacing and printing direction. The printing spacing is the spacing between the conductive printing inks ejected from the printing needle, and the printing direction is the direction of the conductive printing inks.

[0092] In this process, the fiber strips 2 printed by the conductive printing ink in each layer have the same spacing and direction, and the fiber strips 2 between adjacent layers are arranged orthogonally.

[0093] Step S400: Solidify and encapsulate the sensor array model to complete the fabrication of the dexterous hand electronic skin.

[0094] After the sensor array model 1 is fabricated, the activation process is the core step in endowing it with sensing functionality, and accurately selecting the number of upper and lower layer fibers is the key to optimizing performance. The activation method is to squeeze the entire inner liquid of the fiber to subject it to uniform pressure, thereby creating a passage inside without damaging the outer liquid and causing the inner liquid to leak.

[0095] Preferably, the electronic skin includes a two-layer sensor array model, with multiple fiber strips 2 in each array. Once activated, the fiber strips 2 can output electrical signals. The number of fibers to be activated is selected according to the required scenario.

[0096] After activation and fiber quantity optimization, a dual-layer elastomer encapsulation technology is used to protect the sensor array. The inner layer uses low-modulus silicone rubber to ensure a tight fit with the sensor array without affecting its deformation; the outer layer uses high-hardness polyurethane elastomer to improve wear resistance and impact resistance. During the encapsulation process, a stepped transition structure is designed at the edges, and the inner and outer layers are seamlessly bonded through a thermoforming process to form a waterproof and dustproof sealed environment.

[0097] After the activation, fiber quantity optimization, and encapsulation processes described above, the resulting electronic skin can precisely adhere to the surface of the robotic arm. When the robotic arm comes into contact with the external environment, the sensor array can detect changes in physical quantities such as pressure, strain, and vibration in real time, converting them into electrical signals and transmitting them to the control system through built-in flexible circuits. For example, when grasping fragile items, the electronic skin can quickly feed back the contact pressure to the control unit, adjusting the grasping force to prevent damage to the items; when moving on complex terrain, it can sense vibration signals to help the robotic arm adjust its posture and achieve stable walking, thus efficiently realizing information interaction between the robot and the external environment.

[0098] Specifically, in one implementation of this embodiment, step S400 includes the following steps:

[0099] Step S410: Place the multilayer sensor array model into a vacuum drying oven for heating and curing;

[0100] Step S420: The solidified sensor array model is taken out, activated and packaged to obtain the dexterous hand electronic skin.

[0101] After printing, the multilayer sensor array model 1, along with the substrate, needs to be placed in a DFZ vacuum drying oven for heating and curing at a constant temperature of 80℃ for 45 minutes to ensure the coaxial structure is fully formed. Under vacuum heating conditions, the coaxial electrode fiber sample can be heated uniformly, and the stress it experiences is relatively small, making it less prone to deformation or breakage, thereby improving the forming quality and uniformity of the coaxial structure.

[0102] For the cured orthogonal stacked electrode structure array, the number of upper and lower fibers to be activated and encapsulated is precisely selected according to specific test requirements, resulting in an electronic skin that can be used as a robotic arm to realize information interaction between the robot and the external environment.

[0103] The flexible sensor array model 1 of this application can effectively sense various materials, including skin, copper, polylactic acid (PLA) blocks, aluminum, tennis balls, fabrics, paper, and glass. These objects possess different material properties and structural characteristics. By integrating the sensor array model 1 onto a dexterous fingertip, instantaneous signals can be collected in real time by touching the target object. A machine learning algorithm based on the ConvNeXt neural network model was used to train and test the dataset. The results show that the system achieves an average recognition accuracy of over 95% for the aforementioned materials, verifying the discriminability of different material datasets in the feature space and effectively solving the problem of insufficient material adaptability in traditional tactile sensing systems.

[0104] The core components of sensor array model 1 are PDMS, silicon dioxide, PTFE, and liquid metal. Experimental verification shows that the sensor maintains stable electrical signal output characteristics even under electromagnetic interference or temperature and humidity gradient conditions, and the material recognition accuracy is unaffected by environmental parameter fluctuations. Furthermore, during array manufacturing, the printing path can be designed on demand and process parameters adjusted to match the resolution of sensor array model 1 to the accuracy requirements of specific application scenarios, enabling precise capture of fine operational commands and significantly expanding the engineering application scope of tactile sensing systems.

[0105] As attached Figure 3 and attached Figure 4 As shown, this application also proposes a dexterous hand electronic skin. Based on the above-mentioned manufacturing method of the dexterous hand electronic skin, it includes a multi-layer sensor array model 1 arranged in a stacked manner. Each layer of sensor array model 1 includes multiple fiber strips 2, which are arranged at intervals. The fiber strips 2 of two adjacent sensor array models 1 are in a vertical state to form a cross-stacked state, thereby improving the stability of the sensor array model 1.

[0106] In this embodiment, the fiber strip 2 is flat, and the spacing between each layer of fiber strip 2 is 2.2-2.5 mm.

[0107] Specifically, during the printing process, interface-confined coaxial printing technology is used to prepare flexible ultrathin electrode structures. By precisely controlling the interface confinement effect, the flow range of the printing material is actively constrained during the coaxial fiber deposition process, guiding the core-sheath structure to generate synergistic radial deformation, thereby achieving the controllable fabrication of flexible ultrathin sensor array orthogonal stacked electrodes.

[0108] This application achieves three-dimensional solid construction through layer-by-layer material deposition, demonstrating significant advantages over traditional subtractive manufacturing techniques in terms of efficiency in forming complex structures and control of manufacturing costs. Coaxial direct-write printing, a key technology in additive manufacturing, utilizes a unique coaxial feeding mechanism to simultaneously fabricate electrode layers and flexible substrates, constructing multi-layered "core-sheath structures," providing an efficient solution for the integrated manufacturing of flexible electronic devices. Addressing the bottlenecks in ultra-thinning and arraying in existing flexible sensor manufacturing, this application proposes interface-confined coaxial printing technology. During coaxial fiber deposition, this technology precisely controls the interface confinement effect, actively constraining the flow range of the printing material and guiding the "core-sheath" structure to produce synergistic radial deformation. This innovative mechanism effectively overcomes the thickness limitations of traditional coaxial printing, achieving high-precision, high-efficiency, and controllable fabrication of orthogonal stacked electrodes for flexible ultra-thin sensor arrays, providing a new path for the miniaturization and integration of flexible electronic devices.

[0109] Coaxial printing technology is now widely used in fields such as biomedicine, printed electronics, and flexible tactile sensors. This technology can meet the requirements of manufacturing multi-material structures, enabling the simultaneous printing of composite materials, liquid materials, and functionally graded materials. In traditional direct-write printing, component forming often relies on a single-exit nozzle material extrusion device, and the material formed in each print is relatively uniform, limiting the diversity of component shape and function.

[0110] As attached Figure 5 Appendix Figure 6 and attached Figure 7 As shown, this application also proposes a printing device for the above-mentioned method of manufacturing dexterous hand electronic skin, including an inner shaft body 4 and an outer shaft head sleeve 5; the inner shaft body 4 is disposed on a three-axis displacement platform, and a first flow channel 41 and a second flow channel 42 are disposed inside the inner shaft body 4, the first flow channel 41 and the second flow channel 42 being respectively connected to an external feed pump; the outer shaft head sleeve 5 is disposed at the bottom of the inner shaft body 4 and cooperates with the first flow channel 41 and the second flow channel 42 to output two layers of printing ink arranged coaxially.

[0111] In the field of additive manufacturing, the design of coaxial extrusion nozzles is crucial to the accuracy and efficiency of multi-material composite printing. Based on the maintainability and scalability requirements in engineering practice, a modular design has become an effective solution for optimizing nozzle performance. This design concept, by decomposing a complex system into independent and functionally defined sub-modules, not only significantly reduces the difficulty of component replacement and equipment maintenance but also facilitates rapid iterative upgrades of printing equipment.

[0112] In this embodiment, the first flow channel 41 forms a first opening groove at the bottom of the inner shaft body 4, and the bottom of the inner shaft body 4 is provided with a first pipe 43. The first pipe 43 cooperates with the first flow channel 41 and is coaxially located in the first opening groove. The inner shaft head sleeve 5 is provided with a third flow channel 51, and the first pipe 43 is coaxially arranged in the third flow channel 51. The bottom wall of the first pipe 43 and the outer shaft head sleeve 5 are both provided with an inclination angle 52.

[0113] Among them, as attached Figure 5 As shown, the top of the first flow channel 41 and the second flow channel 42 are provided with connectors to facilitate connection with an external feed pump; the middle of the first flow channel 41 is larger than the second flow channel 42, so it can include the second flow channel 42 and the first pipe 43; the lower part of the first pipe 43 and the outer shaft head sleeve 5 is conical, gradually narrowing the second flow channel 42 and the third flow channel 51 so that the diameter of the output ink meets the requirements.

[0114] Further details are attached. Figure 6 and attached Figure 7 As shown, the bottom of the second flow channel 42 and the third flow channel 51 are elliptical and extend outward along the axis of the first pipe 43. Through the convergence of the first pipe 43 and the outer shaft head sleeve 5, and in conjunction with the elliptical flow channel, printing can be facilitated and the ink size output can be more accurate.

[0115] In this embodiment, as shown in the appendix Figure 6 and attached Figure 7 As shown, the outer shaft head sleeve 5 is provided with a positioning hole 53, and the bottom of the inner shaft body 4 is provided with a positioning guide rail 44. The positioning guide rail 44 cooperates with the positioning hole 53 to realize the connection between the outer shaft head sleeve 5 and the inner shaft body 4.

[0116] Specifically, the positioning block and the positioning guide rail 44 are fitted together, and the two can be further fixed by bolts or set screws.

[0117] The precision-machined flow channel system inside the inner shaft body 4, through optimized fluid dynamics design, ensures a stable flow rate and pressure distribution of the internal liquid material during transportation, thereby achieving precise material output control. The outer shaft head sleeve 5 is mainly responsible for the transportation and forming of the external liquid material. Its unique annular flow channel design provides a uniform and stable flow path for the external liquid material, ensuring good encapsulation and continuity of the external liquid material during extrusion.

[0118] The coordinated operation between the two modules is key to achieving coaxial extrusion. The precise fit of the high-precision positioning guide rail 44 effectively ensures the coaxiality of the inner and outer liquid channels in three-dimensional space, providing ideal initial conditions for subsequent printing and thus significantly improving the molding quality and precision control level of multi-material composite printing.

[0119] Compared to traditional printheads with fixed-specification circular pipe configurations, the new coaxial printhead (a combination of the inner shaft body 4 and the outer shaft head sleeve 5) achieves precise control over the dimensional parameters of the inner and outer shaft pipes through a modular design concept. By adjusting key geometric parameters such as the pipe's inner diameter, wall thickness, and length, it can flexibly meet the printing needs of different precision and scale tasks, ranging from micron-level precision manufacturing to macro-scale rapid prototyping. This adjustable parameter feature not only effectively improves the equipment's adaptability to diverse process conditions but also achieves refined control over material extrusion volume and flow rate by optimizing the fluid channel dimensions, further enhancing the stability and controllability of the printing process.

[0120] In terms of nozzle exit shape design, the new coaxial nozzle breaks through the limitations of the traditional circular cross-section. Through innovative mold forming and machining processes, it can achieve various non-circular cross-section exit configurations such as square, elliptical, and racetrack shapes. This diverse exit shape design provides technical support for the manufacturing of complex geometric structures and special textured surfaces. For example, an elliptical exit can form a flat fluid cross-section during extrusion, which is particularly suitable for preparing biomimetic structural materials with directional textures; while a square exit helps to construct three-dimensional framework structures with sharp edges and corners, showing significant advantages in fields with stringent geometric precision requirements, such as microfluidic chips and tissue engineering scaffolds. This morphological diversity greatly expands the application scenarios of the nozzle and provides a broader space for innovation in the design and manufacturing of complex functional structures.

[0121] At the fluid dynamics optimization level, the novel coaxial nozzle incorporates a micro-tilt angle 52 structure design at the nozzle exit. A fluid dynamics simulation model was established to systematically analyze different tilt angle 52 parameters, ultimately determining a 45° exit tilt angle 52 as the optimal configuration. This design effectively optimizes the material flow pattern at the nozzle exit by altering the material extrusion direction and velocity vector distribution. During printing, the tilted exit angle significantly reduces the vertical shear stress generated by gravity, preventing material splashing or structural collapse caused by the superposition of extrusion force and gravity. Experimental results show that printing tilt angles 52 from 30° to 80° can all produce coaxial fibers, but a 45° tilt angle ensures uniform extrusion of both internal and external materials, resulting in optimal electrical output performance. Simultaneously, the 45° tilt angle 52 design creates an impact force with a certain tangential component when the material contacts the printing substrate. This force helps the material spread and bond more tightly on the substrate surface, significantly improving deposition accuracy and interlayer bonding strength, especially during printing on curved or non-planar substrates. In multi-material composite printing applications, this design can achieve more precise material interface fusion by controlling the extrusion angle and speed of different materials, thereby constructing composite functional parts with more robust structures and superior performance.

[0122] In this embodiment, because the coaxial nozzle has many complex curved surfaces and intersecting pipe structures, and the internal and external liquid flow channels require relatively small dimensions, traditional manufacturing methods are insufficient to meet the demands of high precision and complex geometry manufacturing. By using a photopolymerization printing system, the manufacturing time of the component can be significantly shortened, printing efficiency improved, and the risk of deformation reduced.

[0123] In the photopolymerization molding technology system, the developed coaxial extrusion nozzle exhibits excellent structural shape stability and dimensional accuracy retention capabilities. Its overall volume is similar to that of a one-yuan coin, reflecting compact and miniaturized design characteristics. When constructing internal and external liquid flow channels, the photopolymerization printing process achieves refined shaping of the channel inner wall surface thanks to its micron-level layer printing precision. By optimizing photopolymerization parameters (such as exposure time, layer thickness, and resin viscosity), the surface roughness of the flow channels can be controlled within a specified range, significantly lower than that of traditional machining processes.

[0124] This low-roughness flow channel structure effectively suppresses turbulence and eddies by reducing wall friction resistance during fluid transport, ensuring laminar flow and stable material transport within the channel. Simultaneously, refined channel geometry (such as uniform cross-sectional dimensions and smooth transition fillets) reduces fluid stagnation and dead zones, preventing channel blockage caused by localized solidification or sedimentation, thus enabling simultaneous and precise extrusion of internal and external liquid materials during coaxial printing.

[0125] The printing device of this application, through its unique internal flow channel system, not only possesses anti-clogging capabilities but also facilitates disassembly and cleaning through a modular design, ensuring smooth material extrusion. Simultaneously, the design aims to simplify operating procedures, reduce manufacturing costs, improve production efficiency and product performance, and meet diverse application needs. Furthermore, because the aforementioned method for manufacturing the printing device possesses high-resolution printing capabilities, it can effectively manufacture complex microstructures within the coaxial printhead, enhancing the bonding strength between material layers and contributing to high-quality printing results in coaxial printing.

[0126] Other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and practice of the solutions disclosed herein. This invention is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of the invention are indicated by the claims.

Claims

1. A method for manufacturing dexterous hand electronic skin, characterized in that, include: Prepare conductive printing ink and add it into the printing equipment; The printing device is fixed on a three-axis displacement platform and positioned above the printing platform; The triaxial displacement platform and the printing device are started, and a sensor array model is printed by interface confinement. The sensor array model is solidified and packaged to complete the fabrication of the dexterous hand electronic skin.

2. The method for manufacturing the dexterous hand electronic skin according to claim 1, characterized in that, The preparation of conductive printing ink and its addition into the printing device includes: To produce an outer friction layer ink and an inner conductive layer ink.

3. The method for manufacturing the dexterous hand electronic skin according to claim 2, characterized in that, The process of fabricating the outer friction layer ink and the inner conductive layer ink includes: Polydimethylsiloxane, polytetrafluoroethylene, and silica are mixed in a mass ratio of 9:2:1 and then centrifuged and degassed to form the outer friction layer ink.

4. The method for manufacturing the dexterous hand electronic skin according to claim 2, characterized in that, The process of fabricating the outer friction layer ink and the inner conductive layer ink also includes: Liquid metal alloy and polydimethylsiloxane are mixed at a mass ratio of 4:1, and then centrifuged and degassed. The lower layer precipitate is taken as the inner conductive layer ink.

5. The method for manufacturing the dexterous hand electronic skin according to claim 1, characterized in that, The process of activating the triaxial displacement platform and the printing device, and printing a sensor array model through interface confinement, includes: The preset printing path, air pump output pressure, injection hydraulic pump extrusion rate, and the moving speed of the printing device; Start the three-axis displacement platform, the printing equipment, the air pump, and the injection hydraulic pump; The height, angle, and speed of the printing device are adjusted to apply interfacial pressure to the conductive printing ink, actively constraining the flow area of ​​the conductive printing ink and forming a multi-layer sensor array model.

6. The method for manufacturing the dexterous hand electronic skin according to claim 1, characterized in that, The process of solidifying and encapsulating the sensor array model to complete the fabrication of the dexterous hand electronic skin includes: The multi-layer sensor array model was placed in a vacuum drying oven for heating and curing. The solidified sensor array model is removed, activated, and encapsulated to obtain the dexterous hand electronic skin.

7. The method for manufacturing the dexterous hand electronic skin according to claim 1, characterized in that, The preparation of conductive printing ink and its addition into the printing device includes the following steps: The substrate was ultrasonically cleaned using anhydrous ethanol. The surface of the substrate is treated by spraying adhesive onto a 3D printing platform to form a substrate.

8. A dexterous hand electronic skin, based on a method for manufacturing a dexterous hand electronic skin as described in any one of claims 1-7, characterized in that, include: A multi-layer sensor array model is arranged in a stacked manner to form a dexterous hand electronic skin; each layer of the sensor array model includes multiple fiber strips, which are arranged at intervals; the fiber strips of two adjacent sensor array models are in a vertical state to form a cross-stacked state.

9. A printing apparatus for manufacturing a method of dexterous hand electronic skin as described in any one of claims 1-7, characterized in that, include: The inner shaft body is mounted on the triaxial displacement platform; The inner shaft body is provided with a first flow channel and a second flow channel, which are respectively connected to an external feed pump. An outer shaft head sleeve is disposed at the bottom of the inner shaft body; the outer shaft head sleeve cooperates with the first flow channel and the second flow channel to output two layers of printing ink arranged coaxially.

10. The printing apparatus according to claim 9, characterized in that, The first flow channel forms a first opening groove at the bottom of the inner shaft body. A first pipe is provided at the bottom of the inner shaft body. The first pipe cooperates with the first flow channel and is coaxially arranged in the first opening groove. A third flow channel is provided inside the outer shaft head sleeve. The first pipe is coaxially arranged in the third flow channel. The bottom walls of the first pipe and the outer shaft head sleeve are both provided with an inclination angle.

Images