Method for non-contact in-situ printing of circuit pattern and printing device

Abstract

The invention discloses a non-contact in-situ circuit pattern printing method and device, and the method comprises the steps: preparing functional ink which adopts a viscoelastic spinning solution; functional ink is filled into an inner needle head channel of the coaxial air spinning nozzle; guiding airflow with constant pressure is introduced into an outer needle head channel of the coaxial air spinning nozzle through a pressure controller, so that the functional ink extruded from an inner needle head is stretched and focused into continuous fiber jet flow; extruding airflow with constant pressure is introduced into the inner needle head channel through the pressure controller, the motion control device controls and drives the coaxial air spinning nozzle to move according to a preset digital path, and meanwhile, the constant distance between the tail end of the coaxial air spinning nozzle and the surface of the target substrate is kept, so that a fiber network structure is formed on the surface of the target substrate, and a circuit pattern is obtained. According to the invention, high-conformality and personalized circuit patterns can be directly printed on the three-dimensional non-planar human skin surface, and high-fidelity and high-resolution perception of human actions and physiological information without feeling wearing is realized.

Description

Technical Field

[0001] This application relates to the field of circuit pattern printing technology, and in particular to a method and apparatus for non-contact in-situ printing of circuit patterns. Background Technology

[0002] In the field of flexible electronics and wearable devices, a key challenge is how to integrate sensing functions with high fidelity and comfort onto dynamic, irregular biological surfaces. Traditional pre-fabricated sensors (such as silicon- or thin-film-based devices) often struggle to simultaneously meet the requirements of good surface conformality, seamless wearability, and personalized adaptation. Summary of the Invention

[0003] This application aims to address at least one of the technical problems existing in the prior art. To this end, this application proposes a method for non-contact in-situ printing of circuit patterns, which enables the rapid and direct manufacturing of customized, high-fidelity, and wear-insensitive bioelectronic interfaces, solving the industry problem that traditional flexible electronic devices are difficult to integrate intimately and stably with irregular and dynamic human body surfaces.

[0004] This application also provides a printing apparatus.

[0005] A method for non-contact in-situ printing of circuit patterns according to a first aspect of this application is applied to a printing apparatus, the printing apparatus including a coaxial air-spinning nozzle, a motion control device, and a pressure controller. The coaxial air-spinning nozzle has an inner needle channel and an outer needle channel. The motion control device is used to control the motion trajectory of the coaxial air-spinning nozzle, and the pressure controller is used to supply a constant pressure airflow to the inner needle channel and the outer needle channel respectively. The method includes: A functional ink is prepared using a viscoelastic spinning solution; The functional ink is loaded into the inner needle channel; The pressure controller introduces a constant pressure airflow into the outer needle channel, causing the functional ink extruded from the inner needle to be stretched and focused into a continuous fiber jet. The pressure controller introduces a constant pressure of extruded airflow into the inner needle channel, and the motion control device controls the coaxial air-spinning nozzle to move along a preset digital path, while maintaining a constant distance between the end of the coaxial air-spinning nozzle and the target substrate surface, so as to form a fiber network structure on the target substrate surface and obtain a circuit pattern.

[0006] The method for non-contact in-situ printing of circuit patterns according to the embodiments of this application has at least the following beneficial effects: This application embodiment controls the coaxial air-spinning nozzle to move along a preset digital path through a motion control device, achieving a "free path"; by maintaining a constant distance between the end of the coaxial air-spinning nozzle and the target substrate surface, "non-contact" is achieved; a constant pressure guiding airflow is introduced into the outer needle channel through a pressure controller, causing the functional ink extruded from the inner needle to be stretched and focused into a continuous fiber jet, directly forming a fiber network structure on the target substrate surface without the need for a mask, achieving "in-situ printing"; the formed fiber network structure can conform to microscopic fingerprints and macroscopic joint surfaces, with high signal fidelity, enabling the rapid and direct manufacturing of customized, high-fidelity, wearable, and imperceptible bioelectronic interfaces, solving the industry problem of traditional flexible electronic devices being difficult to integrate intimately and stably with irregular and dynamic human body surfaces.

[0007] According to some embodiments of this application, the viscoelastic spinning solution is a polymer composite solution comprising a polymer matrix and functional materials, wherein the polymer matrix is ​​used to provide viscoelasticity and regulate rheology, and the functional materials are used to impart electrical, optical, or sensing properties to the circuit pattern.

[0008] According to some embodiments of this application, the total shear modulus of the viscoelastic spinning solution ranges from 15 Pa to 60 Pa.

[0009] According to some embodiments of this application, the pressure value of the guiding airflow is 750 mbar, and the pressure value of the compressive airflow is 40 mbar.

[0010] According to some embodiments of this application, the preset digital path is obtained through the following steps: Obtain the base data of the target base; The high-strain and low-strain regions are determined based on the substrate data; The preset digital path is determined based on the high strain region and the low strain region, wherein the printing path corresponding to the high strain region is an arc-shaped path that bypasses the high strain region, and the printing path corresponding to the low strain region is a straight path that covers the low strain region.

[0011] According to some embodiments of this application, the constant distance between the end of the coaxial air-spinning nozzle and the surface of the target substrate ranges from 5 mm to 25 mm.

[0012] According to some embodiments of this application, the step of controlling the coaxial air-spinning nozzle to move along a preset digital path via the motion control device includes: The motion control device controls the coaxial air-spinning nozzle to move repeatedly along a preset digital path.

[0013] According to some embodiments of this application, the step of controlling the coaxial air-spinning nozzle to move cyclically multiple times along a preset digital path via the motion control device includes: The motion control device controls the coaxial air-spinning nozzle to move 4 times along a preset digital path.

[0014] A printing apparatus according to a second aspect embodiment of this application includes: The coaxial air-spinning nozzle has an inner needle channel and an outer needle channel; A motion control device is used to control the motion trajectory of the coaxial air-spinning nozzle; A pressure controller is used to supply a constant pressure airflow to the inner needle channel and the outer needle channel respectively; The printing apparatus is used to implement the method for non-contact in-situ printing of circuit patterns as described in the first aspect embodiment above.

[0015] The printing apparatus according to the embodiments of this application has at least the following beneficial effects: This application embodiment controls the coaxial air-spinning nozzle to move along a preset digital path through a motion control device, achieving a "free path"; by maintaining a constant distance between the end of the coaxial air-spinning nozzle and the target substrate surface, "non-contact" is achieved; a constant pressure guiding airflow is introduced into the outer needle channel through a pressure controller, causing the functional ink extruded from the inner needle to be stretched and focused into a continuous fiber jet, directly forming a fiber network structure on the target substrate surface without the need for a mask, achieving "in-situ printing"; the formed fiber network structure can conform to microscopic fingerprints and macroscopic joint surfaces, with high signal fidelity, enabling the rapid and direct manufacturing of customized, high-fidelity, wearable, and imperceptible bioelectronic interfaces, solving the industry problem of traditional flexible electronic devices being difficult to integrate intimately and stably with irregular and dynamic human body surfaces.

[0016] According to some embodiments of this application, the motion control device employs a multi-axis robotic arm.

[0017] Other features and advantages of this application will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing this application. Attached Figure Description

[0018] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 This is a flowchart of a method for non-contact in-situ printing of circuit patterns according to an embodiment of this application; Figure 2 This is a schematic diagram of the structure of a printing apparatus according to an embodiment of this application; Figure 3This is a schematic diagram of a non-contact in-situ printing method for circuit patterns according to an embodiment of this application; Figure 4 This is a schematic diagram of a functional ink of one embodiment of this application being stretched and focused into a continuous fiber jet; Figure 5 This is a schematic diagram of the nozzle path and the printing sensor path according to an embodiment of this application; Figure 6 This is a schematic diagram illustrating the application of a circuit pattern according to an embodiment of this application; Figure 7 This is a microscopic image of the sensing path and its conformity to the skin according to an embodiment of this application; Figure 8 This is a demonstration diagram of a finger movement detection, gesture recognition, and human-computer interaction application based on a printed circuit pattern according to an embodiment of this application; Figure 9 This is a schematic diagram illustrating the application of a printed circuit pattern in tactile perception according to an embodiment of this application; Figure 10 This is a schematic diagram illustrating the application of a printed circuit pattern according to an embodiment of this application in muscle activity; Figure 11 This is a printed schematic diagram of an object material identification interface based on an open-circuit circuit design according to an embodiment of this application; Figure 12 It is an application Figure 11 Waveform change curve of the object material recognition interface.

[0019] Figure label: Coaxial air spinning nozzle 100, inner needle channel 101, outer needle channel 102; Motion control device 200; Pressure controller 300. Detailed Implementation

[0020] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0021] In the description of this application, the use of terms such as "first," "second," etc., is for the purpose of distinguishing technical features only and should not be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated or the order of the technical features indicated.

[0022] In the description of this application, it should be understood that the orientation descriptions, such as up, down, etc., are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application 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 this application.

[0023] In the description of this application, it should be noted that, unless otherwise explicitly defined, terms such as "setup," "installation," and "connection" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this application in conjunction with the specific content of the technical solution.

[0024] In the field of flexible electronics and wearable devices, a key challenge is how to integrate sensing functions with high fidelity and comfort into dynamic, irregular biological surfaces (such as human skin). Traditional pre-fabricated sensors (such as silicon- or thin-film-based devices) often struggle to simultaneously meet the requirements of good surface conformality, seamless wearability, and personalized adaptation.

[0025] Current circuit pattern printing methods and their limitations include: (1) Inkjet printing: Low-viscosity conductive ink is atomized into microdroplets and then sprayed onto a substrate. Its main drawbacks include: Resolution and thickness limitations: The resulting patterns are usually two-dimensional films with feature dimensions (line widths) mostly above tens of micrometers. They are also solid structures, lacking breathability and affecting skin comfort.

[0026] Poor interlayer adhesion and tensile strength: The film formed by stacked droplets is prone to cracking and falling off under dynamic bending or stretching.

[0027] High requirements for substrate flatness: Printing quality is significantly reduced on highly curved or textured skin surfaces (such as knuckles).

[0028] (2) Aerosol jet printing: This method generates a stream of airborne functional material particles, which are then deposited through a focused nozzle. Its main drawbacks include: Complex process and high cost: It requires a sophisticated aerodynamic focusing system, which is complex and has high maintenance costs.

[0029] Material limitations: It is generally suitable for nanoparticle suspensions, but has limited ability to handle high-viscosity solutions of high molecular weight polymers.

[0030] Difficulty in forming fibrous structures: The deposits are mostly particle accumulations or dense films, which cannot directly form an interconnected fibrous network structure with inherent stretchability.

[0031] (3) Electrospinning / blowing. Its main drawbacks are: unstable jet (whipping effect), difficulty in achieving precise patterned direct writing, usually requiring a mask or collector to form specific patterns, and inability to perform customized printing of free paths.

[0032] This application provides a method for non-contact in-situ printing of circuit patterns, which enables the rapid and direct manufacturing of customized, high-fidelity, and wear-insensitive bioelectronic interfaces. This solves the industry problem that traditional flexible electronic devices are difficult to integrate closely and stably with irregular and dynamic human body surfaces.

[0033] The following will combine Figures 1 to 10 The method for non-contact in-situ printing of circuit patterns according to the embodiments of this application will be clearly and completely described. Obviously, the embodiments described below are some embodiments of this application, not all embodiments.

[0034] The method for non-contact in-situ printing of circuit patterns according to the first aspect of this application is applied to a printing apparatus, which includes a coaxial air-spinning nozzle 100, a motion control device 200, and a pressure controller 300. The coaxial air-spinning nozzle 100 has an inner needle channel 101 and an outer needle channel 102. The motion control device 200 is used to control the motion trajectory of the coaxial air-spinning nozzle 100, and the pressure controller 300 is used to introduce airflow at a constant pressure into the inner needle channel 101 and the outer needle channel 102, respectively. The methods include: Functional inks are prepared using viscoelastic spinning solutions. Load the functional ink into the inner needle channel 101; The pressure controller 300 introduces a constant pressure guiding airflow into the outer needle channel 102, which stretches and focuses the functional ink extruded from the inner needle into a continuous fiber jet. A constant pressure extruded airflow is introduced into the inner needle channel 101 through the pressure controller 300, and the coaxial air-spinning nozzle 100 is controlled by the motion control device 200 to move along a preset digital path, while maintaining a constant distance between the end of the coaxial air-spinning nozzle 100 and the target substrate surface, so as to form a fiber network structure on the target substrate surface and obtain a circuit pattern.

[0035] refer to Figures 1 to 5 , Figure 1 This is a flowchart of a method for non-contact in-situ printing of circuit patterns according to an embodiment of this application. Figure 2 This is a schematic diagram of the structure of a printing apparatus according to an embodiment of this application. Figure 3 This is a schematic diagram illustrating a method for non-contact in-situ printing of circuit patterns according to an embodiment of this application. Figure 4 This is a schematic diagram of a functional ink of one embodiment of this application being stretched and focused into a continuous fiber jet. Figure 5This is a schematic diagram of the nozzle path and printing sensor path according to an embodiment of this application.

[0036] This application utilizes functional inks with specific viscoelasticity and spinnability. Through a coaxial aerospinning nozzle 100, guided and stretched by a constant airflow, the ink is formed into a continuous and stable fiber jet. Simultaneously, the coaxial aerospinning nozzle 100 is mounted on a motion control device 200, which controls its movement along a preset array of paths. This allows the fiber jet to be deposited directly onto the surface of a target substrate (such as human skin) without any pre-coated mask in a non-contact manner. After fiber deposition, the solvent rapidly evaporates, forming a firmly adhered, conformal circuit pattern with strain-responsive functionality on the skin. This creates a sensing path that conformally adheres to the skin's microscopic topology and macroscopic curved surfaces. This sensing path is a porous, open network structure composed of submicron interwoven fibers. Unlike dense printed films, it is ultra-thin, breathable, and highly tensile, and can generate reliable resistance change signals with skin deformation. This allows for the direct printing of functional sensing circuits onto living, dynamic, and irregular human skin.

[0037] Furthermore, it should be noted that existing technologies (such as electrospinning / blowing) rely on high-voltage electrostatic fields or high-speed airflow to generate unstable, high-speed whipping jets. The trajectory of these jets is random and divergent, and cannot be precisely controlled. They are essentially a kind of "spraying" or "covering" technique, which can only form irregular fiber mats over large areas. To obtain specific patterns, physical masks must be used to block areas where deposition is not desired, or specially designed collectors (which are essentially masks) must be used, making "direct writing" impossible.

[0038] This application utilizes coaxial laminar airflow to "guide" and "focus" the viscoelastic spinning solution. The functional ink is stretched into a stable, continuous, and nearly straight "fiber rope." This "stable fiber rope," combined with "precise path control," ensures that the fiber deposition point is entirely determined by the motion trajectory. Therefore, we can draw desired circuit patterns on the skin as easily as drawing with a pen: "lifting the pen" (moving the coaxial aerospinning nozzle 100) and "dropping the pen" (turning on the airflow / extrusion). No mask is required; it can be written directly.

[0039] refer to Figure 6 , Figure 6 This is a schematic diagram illustrating the application of a circuit pattern according to an embodiment of this application. Once printed, the circuit pattern can be directly used as a bioelectronic sensor, for example, by printing it on a finger joint to monitor the bending angle and movement frequency of the finger in real time. When the finger bends, the fiber network structure deforms, causing a change in its resistance value. This resistance change signal can be converted into an electrical signal output through an external detection circuit, achieving precise sensing of the human body's movement state.

[0040] According to the non-contact in-situ printing method of the present application embodiment, the present application embodiment controls the coaxial air-spinning nozzle 100 to move along a preset digital path through the motion control device 200 to achieve "free path"; by maintaining a constant distance between the end of the coaxial air-spinning nozzle 100 and the target substrate surface, "non-contact" is achieved; the pressure controller 300 introduces a constant pressure guiding airflow into the outer needle channel 102, so that the functional ink squeezed out from the inner needle is stretched and focused into a continuous fiber jet, and directly forms a fiber network structure on the target substrate surface without the need for a mask, thus achieving "in-situ printing"; the formed fiber network structure can fit microscopic fingerprints and macroscopic joint surfaces, with high signal fidelity, and can realize the rapid and direct manufacturing of customized, high-fidelity, wearable, and imperceptible bioelectronic interfaces, solving the industry problem that traditional flexible electronic devices are difficult to integrate intimately and stably with irregular and dynamic human body surfaces.

[0041] In some embodiments of this application, reference is made to Figure 4 , Figure 4 This is a schematic diagram of a functional ink from one embodiment of this application being stretched and focused into a continuous fiber jet. The viscoelastic spinning solution is a polymer composite solution containing a polymer matrix and functional materials, wherein the polymer matrix is ​​used to provide viscoelasticity and regulate rheology, and the functional materials are used to impart electrical, optical, or sensing properties to the circuit pattern.

[0042] In some embodiments of this application, the total shear modulus of the viscoelastic spinning solution ranges from 15 Pa to 60 Pa.

[0043] In some embodiments of this application, the viscoelastic spinning solution is a mixture of PEDOT:PSS solution and PEO solution, wherein the volume ratio of PEDOT:PSS solution to PEO solution is 4:1, and the PEO molecular weight of the PEO solution is 8 MDa.

[0044] PEDOT:PSS, as a highly conductive polymer, provides excellent conductive pathways for the fiber network, while PEO (polyethylene oxide) mainly contributes to viscoelasticity. The choice of its molecular weight is crucial to the spinnability of the viscoelastic spinning solution and the fiber morphology. In this embodiment, the PEO solution has a molecular weight of 8 MDa. This molecular weight of PEO imparts a suitable degree of chain entanglement to the viscoelastic spinning solution, ensuring the formation of a stable and continuous jet under airflow stretching, and ultimately solidifying into fibers with good mechanical properties.

[0045] In some embodiments, the viscoelastic spinning solution may also be an aqueous polyurethane-based composite material, an ion-conducting hydrogel, a sodium alginate-based composite material, etc. The specific material of the viscoelastic spinning solution should not be regarded as a limitation of this application.

[0046] It should be noted that the waterborne polyurethane-based composite materials, ion-conductive hydrogels, sodium alginate-based composite materials, etc., mentioned here, like the PEDOT:PSS / PEO system in the embodiments of this application, must first be designed and formulated into viscoelastic fluids with "spinnability," that is, meeting specific modulus requirements (total shear modulus range of 15Pa~60Pa). It is this rheological property that makes it behave as a continuous "elastic filament" in the airflow, rather than a fragile liquid column or discrete droplets. It is not "because a certain material is used, it can be directly printed," but rather "any material, as long as it is successfully formulated to meet the specific rheological properties defined in this application and suitable for airflow-guided direct writing, can work in conjunction with the method of this application to achieve direct writing without a mask." "No mask required" is the advantage and direct technical effect brought about by the innovative combination of "specific rheological materials" and "airflow-guided stabilization process."

[0047] In some embodiments of this application, the pressure of the guiding airflow is 750 mbar, and the pressure of the extrusion airflow is 40 mbar. Regarding the airflow parameters, after extensive experimental optimization, the pressure of the guiding airflow was set to 750 mbar. This pressure effectively applies sufficient stretching and focusing force to the viscoelastic spinning solution extruded from the inner needle, overcoming the viscous resistance of the viscoelastic spinning solution and forming a continuous fiber jet with a uniform diameter. Simultaneously, the pressure of the extrusion airflow is 40 mbar. This pressure is used to stably and continuously extrude the functional ink within the inner needle channel 101, working in synergy with the guiding airflow to ensure stable output and deposition of the fiber jet.

[0048] It should be noted that the specific pressure values ​​of the guiding airflow and the compressing airflow are only examples. In practical applications, the pressure values ​​are allowed to fluctuate within a certain range, and other pressure values ​​can also be used (the guiding airflow is preferably in the range of 500 mbar to 1200 mbar, and the compressing airflow is preferably in the range of 10 mbar to 200 mbar). This should not be regarded as a limitation of this application.

[0049] In some embodiments of this application, reference is made to Figure 7 , Figure 7 This is a microscopic image of a sensing path conforming to skin, according to an embodiment of this application. The preset digital path is obtained through the following steps: Obtain the base data of the target base; The high-strain and low-strain regions were determined based on the substrate data; The preset digital path is determined based on the high strain region and the low strain region. The printing path corresponding to the high strain region is an arc-shaped path that bypasses the high strain region, and the printing path corresponding to the low strain region is a straight path that covers the low strain region.

[0050] To ensure that the printed circuit pattern better adapts to the mechanical properties of the target substrate, especially for substrates with different strain regions such as human skin, the preset digital path is obtained through the following steps: First, the substrate data of the target substrate is acquired, for example, by obtaining the three-dimensional morphology and mechanical property distribution information of the substrate through 3D scanning; then, high-strain regions (such as regions with large tensile deformation during joint movement) and low-strain regions (such as relatively flat regions of skin with small deformation) are determined based on the substrate data; finally, the preset digital path is determined based on the high-strain regions and low-strain regions. The printing path corresponding to the high-strain regions is an arc-shaped path that bypasses the high-strain regions to avoid excessive stretching and damage to the fiber network under high strain, while the printing path corresponding to the low-strain regions is a straight path that covers the low-strain regions to ensure the sensing sensitivity and signal stability of these regions.

[0051] In some embodiments of this application, the constant distance between the end of the coaxial air-spinning nozzle 100 and the target substrate surface ranges from 5mm to 25mm. During the printing process, the distance between the end of the coaxial air-spinning nozzle 100 and the target substrate surface is one of the key parameters affecting printing accuracy and fiber deposition quality. Within this range, the guiding airflow can effectively focus the fiber jet while avoiding contact between the end of the coaxial air-spinning nozzle 100 and the target substrate surface or significant influence from airflow disturbances on the target substrate surface, ensuring that the fiber network structure can be accurately deposited on the preset path.

[0052] It should be noted that the range of the constant distance mentioned above is only an example. In practical applications, its range is allowed to fluctuate within a certain range above and below, and should not be regarded as a limitation of this application.

[0053] In some embodiments of this application, the coaxial air-spinning nozzle 100 is controlled to move along a preset digital path by the motion control device 200, including: The motion control device 200 controls the coaxial air-spinning nozzle 100 to move repeatedly along a preset digital path.

[0054] By controlling the coaxial air-spinning nozzle 100 to move repeatedly along a preset digital path through the motion control device 200, the conductivity and structural stability of the circuit pattern can be enhanced. Through the superposition of multiple layers of fibers, a fiber network structure with a certain thickness and density is formed, thereby optimizing its electrical and mechanical properties.

[0055] Preferably, the number of cycles is 4. Experimental verification shows that printing 4 times can ensure that the circuit pattern has good flexibility while meeting the basic requirements for bio-motion signal detection in terms of conductivity and tensile elongation at break. If the number of cycles is too small (e.g., 1-2 times), the fiber network is sparse and the conductive path is discontinuous, resulting in excessive initial resistance and insufficient sensing sensitivity. If the number of cycles is too large (e.g., more than 6 times), the fiber layers are too thick, which increases the interface stiffness, reduces wearing comfort, and is prone to interlayer delamination during dynamic bending.

[0056] In some embodiments, the inner needle of the coaxial air-spinning nozzle 100 is made of 23G blunt-tipped stainless steel.

[0057] In some embodiments of this application, the thickness and line width of the circuit pattern can be precisely controlled by controlling the printing speed (e.g., 50 mm / s) and the number of printing cycles.

[0058] In some embodiments of this application, the target substrate surface is the surface of human skin. During the printing process, the ambient temperature is controlled at 25±2℃, and the relative humidity is controlled at 40%~60%. In-situ printing on the surface of human skin is quite sensitive to environmental parameters. If the temperature is too high (above 30℃), the spinning solution solvent will evaporate too quickly, and the jet will solidify prematurely before reaching the skin surface, affecting the initial adhesion between the fiber and the skin. If the temperature is too low (below 20℃), the solvent will evaporate slowly, and the fibers will easily stick together. When the relative humidity is below 40%, the evaporation of moisture on the skin surface will be accelerated, which may cause local micro-wrinkles on the skin, affecting the printing accuracy. When the relative humidity is above 60%, the solvent evaporation is hindered, the fiber curing time is prolonged, and the fibers are prone to sagging and deformation due to gravity. By setting a local temperature and humidity adjustment device in the printing area, the above parameters can be precisely controlled to ensure the forming quality and stability of the printed circuit pattern on the skin surface.

[0059] refer to Figures 7 to 10 , Figure 7 This is a microscopic image of the sensing path and its conformity to skin, according to an embodiment of this application. Figure 8 This is a demonstration diagram of a finger movement detection, gesture recognition, and human-computer interaction application based on a printed circuit pattern according to an embodiment of this application. Figure 9 This is a schematic diagram illustrating the application of a printed circuit pattern in tactile perception according to an embodiment of this application. Figure 10 This is a schematic diagram illustrating the application of a printed circuit pattern according to an embodiment of this application in muscle activity.

[0060] Example 1: Printing of sensor paths for finger movement detection Functional ink preparation: Prepare a mixed solution of PEDOT:PSS solution and PEO solution (volume ratio 4:1) according to the aforementioned preferred scheme, and stir for 12 hours; Printing setup: Load the functional ink into the syringe and connect it to the inner needle of the coaxial air-spinning nozzle 100. Set the guide air pressure to 750 mbar and the extrusion air pressure to 40 mbar. Install the coaxial air-spinning nozzle 100 onto the motion control device 200; Path planning and printing: A circular path is designed in the software, running from the wrist, through the back of the hand, to the PIP joint of the index finger, and back. At the PIP joint, the path is automatically offset into an arc. The printing speed is set to 50 mm / s, the printing height to 15 mm, and four cycles are executed. The program is then started, and printing is completed on the volunteer's hand.

[0061] Test: A digital source meter was connected via wristband electrodes. Volunteers repeatedly bent their index fingers (0° to 90°), and stable, repeatable resistance changes were recorded with a sensitivity (GF) of approximately 2.5.

[0062] Example 2: Printing of a full-hand gesture recognition interface Based on Example 1, independent sensing paths were designed and printed for each of the five fingers, and all paths converged at the wrist. Connect to a multi-channel data acquisition system; Calibrate the gestures "clenched fist", "open palm", "OK" etc. (record the maximum and minimum resistance values ​​of each path). Volunteers randomly made the above gestures, and the system successfully achieved real-time and accurate classification and reconstruction of the gestures by comparing the real-time resistance values ​​with the threshold, without the need for individualized algorithm training.

[0063] Example 3: Printing of Physiological Signal Monitoring Sensor Path Using the same functional ink that was printed four times (to improve sensitivity), a five-interface physiological electrode was printed on the volunteer's forearm. Connect to a multi-channel neural signal recording system (Intan C3004); The volunteer sat still, and a clear electrocardiogram waveform was successfully acquired, with obvious P wave, QRS complex, and T wave characteristics. The left middle and ring fingers were bent simultaneously, and obvious EMG signals were acquired (bandpass filtered, 0.5-100Hz).

[0064] Furthermore, this circuit pattern can also be applied to the field of tactile sensing. Printed on sensitive areas such as fingertips, it allows for the identification of physical properties like texture and hardness by varying the degree of compression of the fiber network structure due to pressure changes when in contact with different objects. In muscle activity monitoring, the circuit pattern can be printed on the muscle surface. When the muscle contracts or relaxes, the circuit pattern will exhibit corresponding resistance changes in response to the muscle's deformation. Analysis of these signals can assess muscle activity intensity and fatigue levels, providing strong data support for sports rehabilitation and clinical diagnosis.

[0065] Example 4: Printing of an object material recognition interface based on an open-circuit circuit design refer to Figure 11 and Figure 12 , Figure 11 This is a printed schematic diagram of an object material identification interface based on an open-circuit circuit design according to an embodiment of this application. Figure 12 It is an application Figure 11 The waveform change curve of the object material recognition interface is shown in this embodiment. This embodiment demonstrates how to use the method of this application to prepare a touch circuit pattern that can be used to identify the electrical properties of an object.

[0066] 1. Functional Ink and Circuit Printing: The same functional ink (volume ratio 4:1) as in Example 1 was used. A U-shaped sensing path was designed in the software, with each end connected to two predetermined electrode pads. A physical notch with a width of 2mm to -5mm was designed at the center of the top of the U-shape to form an open circuit. Using the printing parameters of Example 1 (printing height 15mm, speed 50mm / s, 4 cycles), this open circuit was printed on the skin of a volunteer's forearm or on a flexible insulating substrate.

[0067] 2. Signal acquisition system connection: Connect the electrode pads at both ends of the "U"-shaped path to a high-precision digital source meter or impedance analyzer via wires to form a monitoring loop.

[0068] 3. Object recognition test: With the circuit in an open-circuit (high impedance) state, a volunteer's fingertip (with the circuit printed on it) or an external conductive probe is used to touch the two ends of the "U"-shaped path gap, causing the touched object itself to act as a conductive bridge, instantly closing the circuit. Tests were conducted using three typical materials as the touching objects: Good conductors: such as copper sheets and aluminum foil.

[0069] Human tissue: the index finger of the volunteer's other hand.

[0070] Insulators: such as glass slides, dry wood (with clean surfaces).

[0071] 4. Signal Processing and Recognition: like Figure 12As shown, the system records the real-time changes in the circuit resistance (or impedance) at the instant of each touch and during the duration of the closed circuit. Due to significant differences in the volume resistivity of different materials and the contact resistance between them and the printing electrodes, the steady-state resistance value after the circuit is closed, the response time for the resistance to reach steady state, and the characteristics of the dynamic change curve will vary. By extracting these characteristic parameters (such as the average resistance change value and the curve slope) and setting simple threshold ranges, the system can effectively distinguish between conductors, semiconductors, the human body, and insulators. For example, a conductor touch causes the resistance to drop sharply to a very low stable value; a human body touch results in a moderate and relatively stable resistance value; while an insulator touch causes only a small and unstable change, or fails to establish a stable conductive path.

[0072] Example 4 demonstrates that the open-circuit sensing structure printed using the method of this application can quickly and easily distinguish material types by utilizing the electrical properties of the object itself. This functionality can be extended to fields such as intelligent interactive interfaces (e.g., distinguishing whether the touch is from a finger, stylus, or other tool), basic material sorting, or interactive environment perception, further demonstrating the powerful potential of this application in constructing multifunctional, customizable skin electronic interfaces.

[0073] It should be noted that the sensing mechanism is not limited to resistive strain sensing; capacitive, piezoelectric, and thermosensitive sensing paths can also be fabricated using this printing method. The different sensing mechanisms primarily correspond to differences in the material formulation of the functional inks and the geometry of the final sensing path. To achieve different sensing mechanisms, functional inks with completely different functional components must be prepared. For the printed fiber network structure, capacitive sensing requires a multi-layer stacked structure; resistive, piezoelectric, and thermosensitive sensing are mostly single-layer structures, but with different material functions.

[0074] In addition, the printing substrate is not limited to human skin, but can also be applied to other irregular, soft biological surfaces or engineered curved surfaces.

[0075] The technical effects of the embodiments of this application include: True "in-situ" and "conformal" integration: Printed directly on the target skin without the need for device transfer, the resulting fiber network can fit microscopic fingerprints and macroscopic joint surfaces, with extremely high signal fidelity; Seamless wearable: The sensing path is made of interwoven fibers that are submicron thick and micron wide, with an open structure (porosity > 50%), which is breathable and moisture-wicking, and hardly affects the skin's natural perception and physiological functions. Excellent mechanical robustness: The crimped structure of the fiber network endows it with inherent stretchability (>50% strain). Experiments show that the printed path can withstand >1000 mechanical stretching cycles and >500 knuckle bending cycles with stable electrical response; High-throughput, high-design-freedom manufacturing: Printing speeds up to 50 mm / s, no need for masks or 3D digital models, and the ability to quickly draw arbitrarily complex circuit patterns via software programming, enabling personalized customization. Full-coverage printing with a single hand can be completed within 10 minutes. Instant repair capability: After local damage, the same equipment can be used to perform precise repairs in situ, restoring the sensing function and extending the service life.

[0076] The application effects (data support) of this application embodiment include: Gesture recognition: The sensor path is printed on the five fingers, and a simple threshold algorithm is used to realize real-time, training-free gesture reconstruction, which can be used directly by different users; Human-computer interaction: Successfully mapped and controlled a multi-finger robotic hand in real time with a latency of less than 100 milliseconds; Physiological monitoring: The path printed on the forearm can clearly record electrocardiogram and electromyography (ECG, EMG); the path printed on the abdomen can distinguish different breathing patterns (deep breathing, normal breathing, rapid breathing). Haptic sensing: Using a network of four independent paths, it can identify six discrete touch areas with an accuracy of over 95%.

[0077] The economic and social effects of this application's embodiments include: Promoting personalized medicine and health monitoring: Providing low-cost, customized, and precise measurement tools for rehabilitation assessment and remote patient monitoring; Revolutionizing the human-computer interaction interface: providing a more natural and comfortable input method for AR / VR and the metaverse; Promote new models for flexible electronics manufacturing: develop towards a distributed manufacturing model of "on-demand production and instant deployment".

[0078] A printing apparatus according to a second aspect embodiment of this application includes a coaxial air-spinning nozzle 100, a motion control device 200, and a pressure controller 300.

[0079] The coaxial air-spinning nozzle 100 has an inner needle channel 101 and an outer needle channel 102; Motion control device 200 is used to control the motion trajectory of coaxial air spinning nozzle 100; The pressure controller 300 is used to supply airflow at a constant pressure to the inner needle channel 101 and the outer needle channel 102 respectively; The printing apparatus is used to implement a method for non-contact in-situ printing circuit patterns as described in the first aspect embodiment above.

[0080] According to the printing apparatus of this application embodiment, the coaxial air-spinning nozzle 100 is controlled by the motion control device 200 to move along a preset digital path to achieve "free path"; "non-contact" is achieved by maintaining a constant distance between the end of the coaxial air-spinning nozzle 100 and the target substrate surface; and a constant pressure guiding airflow is introduced into the outer needle channel 102 by the pressure controller 300, so that the functional ink squeezed out from the inner needle is stretched and focused into a continuous fiber jet, and a fiber network structure is directly formed on the target substrate surface without the need for a mask, achieving "in-situ printing"; the formed fiber network structure can fit microscopic fingerprints and macroscopic joint surfaces, with high signal fidelity, and can realize the rapid and direct manufacturing of customized, high-fidelity, wearable, and imperceptible bioelectronic interfaces, solving the industry problem that traditional flexible electronic devices are difficult to integrate intimately and stably with irregular and dynamic human body surfaces.

[0081] In some embodiments of this application, reference is made to Figure 2 , Figure 2 This is a schematic diagram of the printing apparatus according to an embodiment of this application. The motion control device 200 employs a multi-axis robotic arm. The multi-axis robotic arm has extremely high motion precision and flexibility, and can drive the coaxial air-spinning nozzle 100 to perform complex movements in three-dimensional space according to a preset digital path, precisely controlling the position, orientation, and distance of the coaxial air-spinning nozzle 100 from the target substrate surface, thereby meeting the in-situ printing requirements of target substrate surfaces with different shapes and curvatures.

[0082] It should be noted that the motion control device 200 may also adopt other structures, which should not be regarded as a limitation of this application.

[0083] Additionally, one embodiment of this application provides a control device comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor. The processor and the memory can be connected via a bus or other means.

[0084] Memory, as a non-transitory computer-readable storage medium, can be used to store non-transitory software programs and non-transitory computer-executable programs. Furthermore, memory may include high-speed random access memory, and may also include non-transitory memory, such as at least one disk storage device, flash memory device, or other non-transitory solid-state storage device. In some embodiments, memory may optionally include memory remotely located relative to the processor, and these remote memories can be connected to the processor via a network. Examples of such networks include, but are not limited to, the Internet, intranets, local area networks, mobile communication networks, and combinations thereof.

[0085] The non-transient software program and instructions required for determining the preset digital path in the non-contact in-situ printing circuit pattern method of the above embodiments are stored in the memory. When executed by the processor, the method for determining the preset digital path in the non-contact in-situ printing circuit pattern method of the above embodiments is executed.

[0086] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs.

[0087] Furthermore, one embodiment of this application provides a computer-readable storage medium storing computer-executable instructions that are executed by a processor or controller, such as the processor of the aforementioned control device, causing the processor to perform the method for determining a preset digital path in the non-contact in-situ printing circuit pattern method described in the above embodiments.

[0088] It will be understood by those skilled in the art that all or some of the steps and systems in the methods disclosed above can be implemented as software, firmware, hardware, and suitable combinations thereof. Some or all of the physical components can be implemented as software executed by a processor, such as a central processing unit, digital signal processor, or microprocessor, or as hardware, or as an integrated circuit, such as an application-specific integrated circuit. Such software can be distributed on a computer-readable medium, which can include computer storage media (or non-transitory media) and communication media (or transient media). As is known to those skilled in the art, the term computer storage media includes volatile and non-volatile, removable and non-removable media implemented in any method or technology for storing information (such as computer-readable instructions, data structures, program modules, or other data). Computer storage media includes, but is not limited to, RAM, ROM, EEPROM, flash memory or other memory technologies, CD-ROM, digital versatile disc (DVD) or other optical disc storage, magnetic cartridges, magnetic tape, disk storage or other magnetic storage devices, or any other medium that can be used to store desired information and is accessible to a computer. Furthermore, as is known to those skilled in the art, communication media typically contain computer-readable instructions, data structures, program modules, or other data in modulated data signals such as carrier waves or other transmission mechanisms, and may include any information delivery medium.

[0089] The embodiments of this application have been described in detail above with reference to the accompanying drawings. However, this application is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of this application.

Claims

1. A method for non-contact in-situ printing of circuit patterns, characterized in that, The invention is applied to a printing device, which includes a coaxial air-spinning nozzle, a motion control device, and a pressure controller. The coaxial air-spinning nozzle has an inner needle channel and an outer needle channel. The motion control device is used to control the motion trajectory of the coaxial air-spinning nozzle, and the pressure controller is used to supply a constant pressure airflow to the inner needle channel and the outer needle channel, respectively. The method includes: A functional ink is prepared using a viscoelastic spinning solution; The functional ink is loaded into the inner needle channel; The pressure controller introduces a constant pressure airflow into the outer needle channel, causing the functional ink extruded from the inner needle to be stretched and focused into a continuous fiber jet. The pressure controller introduces a constant pressure of extruded airflow into the inner needle channel, and the motion control device controls the coaxial air-spinning nozzle to move along a preset digital path, while maintaining a constant distance between the end of the coaxial air-spinning nozzle and the target substrate surface, so as to form a fiber network structure on the target substrate surface and obtain a circuit pattern.

2. The method for non-contact in-situ printing of circuit patterns according to claim 1, characterized in that, The viscoelastic spinning solution is a polymer composite solution containing a polymer matrix and functional materials, wherein the polymer matrix is ​​used to provide viscoelasticity and regulate rheology, and the functional materials are used to impart electrical, optical, or sensing properties to the circuit pattern.

3. The method for non-contact in-situ printing of circuit patterns according to claim 1 or 2, characterized in that, The total shear modulus of the viscoelastic spinning solution ranges from 15 Pa to 60 Pa.

4. The method for non-contact in-situ printing of circuit patterns according to claim 1, characterized in that, The pressure of the guiding airflow is 750 mbar, and the pressure of the compressive airflow is 40 mbar.

5. The method for non-contact in-situ printing of circuit patterns according to claim 1, characterized in that, The preset digital path is obtained through the following steps: Obtain the base data of the target base; The high-strain and low-strain regions are determined based on the substrate data; The preset digital path is determined based on the high strain region and the low strain region, wherein the printing path corresponding to the high strain region is an arc-shaped path that bypasses the high strain region, and the printing path corresponding to the low strain region is a straight path that covers the low strain region.

6. The method for non-contact in-situ printing of circuit patterns according to claim 1, characterized in that, The constant distance between the end of the coaxial air-spinning nozzle and the target substrate surface ranges from 5mm to 25mm.

7. The method for non-contact in-situ printing of circuit patterns according to claim 1, characterized in that, The step of controlling the coaxial air-spinning nozzle to move along a preset digital path via the motion control device includes: The motion control device controls the coaxial air-spinning nozzle to move repeatedly along a preset digital path.

8. The method for non-contact in-situ printing of circuit patterns according to claim 7, characterized in that, The step of controlling the coaxial air-spinning nozzle to move cyclically multiple times along a preset digital path via the motion control device includes: The motion control device controls the coaxial air-spinning nozzle to move 4 times along a preset digital path.

9. A printing apparatus, characterized in that, include: The coaxial air-spinning nozzle has an inner needle channel and an outer needle channel; A motion control device is used to control the motion trajectory of the coaxial air-spinning nozzle; A pressure controller is used to supply a constant pressure airflow to the inner needle channel and the outer needle channel respectively; The printing apparatus is used to implement the method for non-contact in-situ printing of circuit patterns as described in any one of claims 1 to 8.

10. The printing apparatus according to claim 9, characterized in that, The motion control device employs a multi-axis robotic arm.

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