Fabricating a fabric hybrid electronic integrated system by laser fusion - Patent Application 20100122633

Abstract

To provide a fabric hybrid electronic system that can realize multiple functions such as sensing detection and signal transmission, and also has stable performance that can withstand washing and rubbing. [Solution] The system includes a chip component, a laser-induced flexible sensor, a fabric substrate, a conductive fabric line, a physiological electrode, and a vertical interconnection via, and uses the laser's material modification ability to form a patterned sensor 131 on the surface 111 of the fabric substrate, uses the laser's micro-cutting ability to form patterned flexible electrodes and interconnection wires, and forms highly stable vertical interconnection vias by infiltrating a conductive composite into the inherent structure of the fabric, and welds the chip electronic device to form a fabric hybrid electronic integrated system.

Description

[Technical Field]

[0001] The present invention belongs to the technical field of wearable electronics, and relates to intelligent electronic fabrics, especially to a fabric hybrid electronic integrated system manufactured by laser fusion. [Background technology]

[0002] Fabrics are the most familiar carriers of items in human daily life. Fabric-based electronic systems effectively combine the information processing advantages of electronic devices with the inherent advantages of fabrics, endowing breathable, protective, and skin-friendly fabrics with the capabilities of perception, driving, communication, and computing. This will shorten the distance between humans and flexible electronic systems, potentially leading to widespread applications in fields such as precision medicine and human-computer interaction.

[0003] There are three main approaches to fabric electronic systems, depending on the integration of silicon-based electronic devices. The first is to integrate common silicon-based chips into commercially available substrates other than fabric, leaving only the inherently flexible devices on the fabric. This solution cannot overcome the mechanical incompatibility between commercially available substrates and the human body surface, making it difficult to ensure comfort when worn. The second is to abandon silicon-based chips and weave electronic devices into functionalized fibers. This all-fiber electronic fabric offers signal processing, visual interaction, and wireless transmission capabilities, but it faces challenges in functional versatility and interface versatility. The third is to integrate silicon-based chips onto fabric substrates. This method is more direct and flexible, and can maximize the advantages of silicon-based electronic devices, but its functional density, wearing comfort, and wearing fit need to be improved.

[0004] This invention addresses the challenge of integrating existing fabric electronic systems with rigid components by using laser fusion manufacturing technology as a tool, combined with process improvements such as transfer printing, to build a unified heterogeneous integrated system that includes functionalized fabric, flexible electronic elements, silicon-based chips, two-layer conductive fabric lines, and vertical interconnect vias. This system can realize versatile circuit functions on a single fabric, thereby improving the portability and functional density of fabric electronic systems.

[0005] Compared with existing electronic fabric technologies, the present invention significantly improves the degree of circuit integration and range of applications by forming independent wiring circuits on the front and back of the fabric, and can be applied to conventional chip-type package chips, and the wires can be soldered, making it more widely applicable. Summary of the Invention [Problem to be solved by the invention]

[0006] The objective of the present invention is to address the shortcomings of the prior art by providing a fabric hybrid electronic integrated system manufactured by laser fusion, which utilizes the thermal effect of a CO2 laser or continuous laser to modify the surface of a fabric to form a laser-induced flexible sensor with sensory functions, and utilizes the micro-cutting capabilities of a pulsed laser to form patterned conductive fabric lines and physiological electrodes on the fabric substrate, combining multiple laser manufacturing techniques with other manufacturing techniques to achieve the integrated integration of electronic components and fabric. The manufacturing method proposed in this invention can integrate functionalized fabric, flexible electronic elements, rigid electronic components, and two-layer conductive fabric lines on fabric, and the resulting fabric hybrid electronic system not only achieves multiple functions such as sensing detection and signal transmission, but also has stable performance that can withstand washing and rubbing. [Means for solving the problem]

[0007] The technical solutions adopted by the present invention to solve the above technical problems are as follows:

[0008] A fabric hybrid electronic integrated system manufactured by laser fusion, comprising a fabric substrate, conductive fabric lines, physiological electrodes, vertical interconnection vias, laser-induced flexible sensors, and chip components, all of which are tightly integrated on one fabric substrate and distributed on both sides of the fabric substrate, and communicate with each other to realize the overall circuit function, and its manufacturing process specifically includes: 1) Formation of a laser-induced flexible sensor: utilizing the photothermal effect of a CO2 laser or continuous green light with a wavelength of 532 nm, treating a precursor material on a fabric substrate or its surface according to a pre-designed pattern, inducing reactions such as carbonization, phase separation, or reduction sintering, to generate a laser-induced flexible sensor on one side of the fabric substrate for detecting physical and chemical signals on the body surface, and then drawing the sensor out from the other side of the fabric substrate; 2) Forming vertical interconnection vias: In the areas of the fabric substrate where vias need to be formed to connect the circuits on both sides, the conductive paste is infiltrated into the texture structure of the fabric substrate at the areas by gas pressure injection, so as to connect the corresponding areas of the fabric substrate from the front to the back; 3) Forming conductive fabric lines and physiological electrodes: using an ultraviolet nanosecond laser to cut the conductive fabric according to a pre-designed pattern to form conductive fabric lines and physiological electrodes, and then using a transfer method to transfer the conductive fabric lines and physiological electrodes to both sides of the fabric substrate, and the conductive fabric lines and physiological electrodes on both sides are connected through the vertical interconnection vias; 4) Integrating chip components: using low melting point solder paste to weld the chip components to the conductive fabric lines to form a complete circuit.

[0009] Further, the fabric substrate is one or more of modal knit fabric, medical nonwoven fabric, polyimide PI fabric, or polyester taffeta knit fabric.

[0010] Furthermore, the formation of the laser-induced flexible sensor specifically involves using a CO2 laser to carbonize one side of the fabric substrate according to a pre-designed pattern to produce a laser-induced graphene sensor, or using continuous green light with a wavelength of 532 nm to induce a phase separation reaction of poly(3,4-ethylenedioxythiophene):polybenzenesulfonic acid (PEDOT:PSS) on the fabric surface to produce a laser-induced PEDOT:PSS sensor, or using continuous green light with a wavelength of 532 nm to induce a reduction sintering reaction of silver nanoink on the fabric surface to produce a laser-induced metal sensor, and then pulling out the above sensor from the other side of the fabric substrate.

[0011] Furthermore, the conductive paste is an intermetallic compound LM / Cu NP paste formed by mixing liquid metal and copper nanoparticles in a centrifugal mixer or a high-speed defoamer.

[0012] Furthermore, the manufacturing of the conductive fabric lines and physiological electrodes is a combination of laser cutting of the conductive fabric and transfer method. In the case of laser cutting, a water-soluble sacrificial layer is used to temporarily fix the conductive fabric lines and physiological electrodes, and after cutting is completed, the conductive fabric lines and physiological electrodes are transferred onto the fabric substrate, and finally the sacrificial layer is dissolved with water to avoid damage to the fabric substrate by the laser.

[0013] Furthermore, the manufacturing method of the conductive fabric line and physiological electrode specifically includes the steps of laminating a layer of adhesive film (AL) on one side of a metal fabric (MT) and laminating a layer of water-soluble sacrificial layer (SL) on the other side of the metal fabric to form an AL / MT / SL structure, using an ultraviolet nanosecond laser to cut out a patterned conductive circuit from the two layers of AL and MT, leaving the SL as it is, and attaching the entire AL / MT / SL to a fabric substrate with the AL side, followed by immersing in water to remove the SL layer softened in water, drying the AL / MT layer attached to the fabric substrate, and peeling off the excess AL / MT layer other than the patterned conductive circuit to form a conductive fabric line or physiological electrode.

[0014] Furthermore, the low melting point solder paste is a paste obtained by mixing a solder paste with an aluminum flux. [Effects of the Invention]

[0015] The advantages of the present invention are as follows:

[0016] The dual-layer conductive circuit, which realizes independent wiring on a single piece of fabric, enables a more highly integrated circuit layout, and separates the rigid electronic elements from the flexible electronic elements that come into contact with the skin on the front and back of the fabric, ensuring comfort when worn. Based on this, it is possible to collect and wirelessly transmit multiple physiological signals on a single piece of fabric, and this has been verified in human experiments during exercise. [Brief explanation of the drawings]

[0017] [Figure 1] Schematic diagram of the fabrication of a laser-induced graphene sensor. [Figure 2] FIG. 1 is a schematic diagram of the fabrication of LM / Cu NP VIAs. [Figure 3] The resistance change of a single-layer conductive fabric line and a double-layer conductive fabric line with four LM / Cu NP VIAs when repeatedly bent. [Figure 4]Images of LM / Cu NP VIAs fabricated into various everyday textiles and illuminating LEDs. [Figure 5] FIG. 1 is a schematic diagram of the production of a two-layer conductive fabric line. [Figure 6] FIG. 1 is a schematic diagram of the production of a two-layer conductive fabric line. [Figure 7] 1 is an image of a fabric hybrid electronic integrated system produced by this process in a bent state. [Figure 8] The electrocardiogram signals collected after (bottom) and before (top) rubbing of a fabric-hybrid electronic integrated system manufactured by this process by hand for 20 seconds. [Figure 9] Images of a fabric-hybrid electronic integrated system produced by this process before (top) and after (bottom) washing. [Figure 10] Photographs of the multifunctional wireless fabric sensing chip (left) fabricated by this process, its placement on the human body (center), and the signal visualization interface (right). DETAILED DESCRIPTION OF THE INVENTION

[0018] The technical solutions of the present invention will be described in more detail below with reference to the drawings and specific embodiments.

[0019] According to a specific embodiment of the present invention, the fabric hybrid electronic integrated system manufactured by laser fusion specifically includes the following steps:

[0020] (1) Fabrication of laser-induced graphene (LIG) sensors: We select polyimide (PI) fabric as the substrate, and use a CO2 laser to irradiate laser light onto the PI fabric to convert the PI into LIG through a photothermal reaction, thereby obtaining a patterned LIG sensor that is sensitive to the temperature and strain of the body surface. Using a CO2 laser, laser light is irradiated onto the connection of the LIG sensor from the other side of the PI fabric substrate, causing the LIG to penetrate the thickness of the PI fabric, thereby allowing the LIG sensor to be pulled out from the other side of the PI fabric.

[0021] (2) Vertical Interconnect Via (VIA) Fabrication: First, liquid metal (LM) and copper nanoparticles (Cu NPs) are mixed in a centrifugal mixer to form an LM / Cu NP paste with good wettability. Then, the paste is printed at predetermined positions on both sides of a PI fabric substrate. Using an air gun, air is blown onto the LM / Cu NP paste on both sides to penetrate into the pores of the PI fabric, making the LM / Cu NPs on both sides of the PI fabric conductive along the vertical direction, thereby obtaining LM / Cu NP VIAs.

[0022] (3) Fabrication of double-layer conductive fabric lines and physiological electrodes by combining laser cutting and transfer printing: A laser-punched adhesive film (AL) is attached to a metallized fabric (MT) to form an AL / MT. A self-adhesive, water-soluble sacrificial layer (SL) is then attached to the MT side of the AL / MT to form an AL / MT / SL. An ultraviolet nanosecond laser is then used to cut the AL / MT / SL from the AL side. The laser spot moves along the conductive fabric lines and the outer contour of the physiological electrode. The laser energy cuts the AL and MT but not the SL. The AL side of the AL / MT / SL is then attached to the PI fabric substrate to form the PI / AL / MT / SL. The PI / AL / MT / SL is then immersed in water to decompose the SL, yielding the PI / AL / MT. After drying, the excess AL / MT is peeled off along the laser-cut contour, yielding a conductive fabric line and physiological electrode adhered to the PI fabric. The PI / AL / MT can be hot-pressed to further improve the adhesion of the AL. By repeating the above procedure on the other side of the PI fabric substrate, a double-layer conductive fabric line can be obtained. The PI fabric substrate electrically insulates the conductive fabric lines of different layers and only conducts them at the location of the LM / Cu NP VIA.

[0023] (4) General chip element integration: The above process results in patterned conductive fabric lines and physiological electrodes on the surface of the PI fabric. The solder paste and aluminum flux are mixed in a 5:1 volume ratio to obtain a mixed paste with a low melting point that can remove the oxide layer on the surface of the conductive fabric lines. This mixed paste is then used to weld chip devices (SMDs) to the conductive fabric lines.

[0024] The fabric hybrid electronic integrated system manufactured using the technical solution of this invention can operate normally even after washing and rubbing, and the integration reliability of the electronic components and the fabric substrate is high. Furthermore, the dual-layer conductive circuit, which realizes independent wiring in a single-layer fabric, realizes general-purpose circuit functions on the breathable fabric substrate, and can wirelessly monitor three signals: heart rate, respiration, and electrocardiogram, without the need for additional commercially available circuit boards or pull wires. Some key technical points are as follows:

[0025] (1) Combining laser cutting with the transfer method prevents laser spill energy from damaging the fabric substrate. A relatively high laser energy is often required to smoothly remove excess conductive fabric along the laser cut. If uncut conductive fabric is attached to a fabric substrate and then laser cut without using the transfer method, spilled laser energy will affect the fabric substrate, damaging its structural integrity and appearance. When using the transfer method, a sacrificial layer, rather than the fabric substrate, is present underneath the conductive fabric during laser cutting, preventing spilled laser energy from affecting the fabric substrate. After cutting is complete, the conductive fabric and physiological electrodes are spatially discontinuous, and their relative positions are fixed by the sacrificial layer. When they are transferred onto the fabric substrate, the sacrificial layer can be dissolved in cold water, making the transfer process gentle and preventing damage to the fabric substrate and conductive medium.

[0026] (2) The tangential force provided by the centrifugal mixer is utilized to facilitate the preparation of LM / Cu NP paste. Intermetallic compounds formed by the reaction of gallium-based liquid metal with other metal nanoparticles are semi-solid and possess paste-like physical properties. They overcome the high surface tension of common LMs, such as eutectic gallium indium and gallium indium tin, and are easily coated on rough fabric surfaces. These intermetallic compounds are typically produced by manual grinding, acid treatment, or alkali treatment. Manual grinding is inefficient and results in uneven dispersion of the LM and Cu NPs. Acid treatment damages the Cu NPs to a certain extent, making it difficult to control the amount used. Alkali treatment, such as immersion in NaOH solution, leaves NaOH residue in the paste, making it difficult to remove. This invention utilizes the tangential force generated during the centrifugal process to destroy the oxide film on the LM surface, allowing the LM and Cu NPs to fully react during the mixing process. This eliminates the need for additional chemical reagents, achieves uniform mixing, and requires only one process step. The finally formed LM / Cu NPs have a certain fluidity and can infiltrate into the pores of the fabric by gas pressure injection to form LM / Cu NP VIAs.

[0027] (3) Welding is performed using a paste made by mixing solder paste and aluminum flux. The outermost layer of commercially available conductive fabric is mainly nickel metal, and its oxide layer is difficult to remove with conventional fluxes in solder paste flux. By using aluminum flux, the nickel oxide layer can be removed, and then the conductive fabric can be welded with solder paste. By using a mixture of solder paste and aluminum flux, the removal of the nickel oxide layer and welding with solder paste can be achieved in one step, reducing the number of processes.

[0028] in particular, As shown in Figure 1, to fabricate the LIG sensor, first, the front surface 111 of the PI fabric substrate is processed with a CO2 laser 12 (wavelength 10.6 μm, spot radius 76 μm) to form a patterned LIG sensor 131 and a positioning hole (diameter approximately 600 μm). After the LIG sensor is coated with Ecoflex 00-50, the CO2 laser 12 is used to process LIG pull-out points 132 in the overlapping area of ​​the back surface 112 of the PI fabric substrate and the LIG sensor 131, thereby forming a LIG conductive path 133 through the fabric in the cross section 113 of the PI fabric substrate, and finally, the LIG sensor is pulled out from the other side 112 of the PI fabric substrate.

[0029] As shown in Figure 2, to fabricate a VIA, first, liquid metal EGaIn and Cu NPs are mixed in a mass ratio of 50:1 with a fast defoaming agent to synthesize an LM / Cu NP paste. Next, the LM / Cu NP paste is printed at the target location using a polyethylene terephthalate (PET) mask 21 and a brush. Air is then blown onto one side of the LM / Cu NP paste 221 using an air blow gun (outlet diameter 3 mm, pressure 200 kPa). The PI fabric substrate is then turned over, and the same blowing operation is performed on the other side of the LM / Cu NP paste 222. Finally, an LM / Cu NP VIA 223 is formed where the LM / Cu NP paste 221 and LM / Cu NP paste 222 overlap.

[0030] Repeated bending experiments were conducted on a single-layer conductive fabric line and a double-layer conductive fabric line with four LM / Cu NP VIAs, as shown in Figure 3. The upper graph shows the change in resistance when the single-layer conductive fabric line was repeatedly bent, and the lower graph shows the change in resistance when the double-layer conductive fabric line with four LM / Cu NP VIAs was repeatedly bent. The two wires exhibited similar interference resistance, indicating that the LM / Cu NP VIAs did not affect the basic functionality of the fabric circuit.

[0031] As shown in Figure 4(a), (b), (c), and (d), a lit LED and an LM / Cu NP VIA are connected in series on a modal knit fabric, a medical nonwoven fabric, a PI fabric, and a polyester tough woven fabric, respectively. Taking Figure 4(a) as an example, an LED is welded to electrodes 41 and 42, and electrodes 42 and 43 are connected to the circuit on the backside of the fabric through two LM / Cu NP VIAs. When power is supplied to electrodes 41 and 43, the LED lights up. This demonstrates that the proposed LM / Cu NP VIA can meet the design requirements of complex fabric circuits and realize interlayer transmission of physiological signals.

[0032] As shown in Figure 5, to fabricate a two-layer conductive fabric line, a layer of adhesive film (AL) 53 is pressed onto one side of a metal fabric (MT) 51, and a layer of adhesive, water-soluble sacrificial layer (SL) 52 is pressed onto the other side of the metal fabric 51. Next, a patterned conductive circuit is cut out from the two layers of metal fabric (MT) 61 and adhesive film (AL) 53 using an ultraviolet nanosecond laser 54 (wavelength 355 nm, spot radius 16 μm), leaving the underlying water-soluble sacrificial layer (SL) 52 in place to temporarily fix the conductive circuit. The circular frame in the upper right corner of the figure is a partially enlarged schematic diagram of the cut area.

[0033] As shown in Figure 6, the AL / MT / SL film is attached to a fabric substrate 61 and then immersed in water. The SL film 62 can be removed after softening in water. The remaining AL / MT layer attached to the fabric substrate is then dried, and the excess AL / MT 631 is peeled off, leaving the patterned AL / MT 632 as a conductive fabric line or physiological electrode. The same process is repeated on the other side of the fabric substrate 61 to obtain a double-sided circuit. The front and back circuits are connected by LM / Cu NP vias 64, thereby realizing a vertically interconnected two-layer fabric circuit. Finally, both sides of the two-layer fabric circuit are hot-pressed at 80°C to strengthen the adhesion between the conductive fabric line, electrode, and fabric substrate.

[0034] To verify the bending resistance of the fabric hybrid electronic system, the fabric was bent to a curvature radius of 25 mm, as shown in Figure 7, but no effect was observed on the chip elements on the fabric, demonstrating that the fabric hybrid electronic system has excellent bending resistance.

[0035] To further verify the stability of the fabric-hybrid electronic integrated system, the fabric was manually rubbed for approximately 20 seconds, and then electrocardiogram signals were collected, as shown in Figure 8. The upper image shows the signal collected before rubbing, and the lower image shows the signal collected after rubbing. The electrocardiogram signals collected by the system before and after rubbing were found to be nearly identical, demonstrating the considerable durability of the fabric-hybrid electronic integrated system.

[0036] To further verify the washability of the fabric-hybrid electronic integrated system, the fabric was soaked in detergent and then hand-washed and ultrasonically washed, as shown in Figure 9. The top image shows the fabric before washing, and the bottom image shows the fabric after washing. After washing, it was found that the dirt and residual solder on the fabric had been removed. Furthermore, the Bluetooth module was still able to communicate with a mobile phone, facilitating long-term maintenance of the fabric-hybrid electronic integrated system.

[0037] As shown in Figure 10, the LIG sensor, physiological electrodes, double-layer conductive fabric lines, and rigid silicon-based chip were integrated into a single piece of fabric using a laser fusion manufacturing process. To verify the signal collection and transmission capabilities of the fabric-hybrid electronic integrated system, the fabric was placed in an appropriate position near the left chest of a subject, who then performed an indoor cycling exercise. During exercise, the fabric-hybrid electronic integrated system simultaneously collected three physiological signals: heart rate, respiration, and electrocardiogram, and wirelessly transmitted the data to a host computer for visualization and real-time processing.

Claims

1. A method for manufacturing a fabric hybrid electronic integrated system by laser fusion, the fabric hybrid electronic integrated system comprising: a fabric substrate, conductive fabric lines, physiological electrodes, vertical interconnection vias, laser-induced flexible sensors, and chip components, the fabric substrate being one or more of modal knit fabric, medical nonwoven fabric, polyimide PI fabric, or polyester taffeta knit fabric, all electronic components being tightly integrated on one fabric substrate and distributed on both sides of the fabric substrate, and communicating to realize the overall circuit function, the manufacturing of which specifically includes: 1) Forming a laser-induced flexible sensor: using a laser to modify the fabric substrate or a precursor material on its surface according to a pre-designed pattern, thereby generating a laser-induced flexible sensor on one side of the fabric substrate for detecting physical and chemical signals on the body surface, and pulling the sensor out from the other side of the fabric substrate; 2) Forming vertical interconnection vias: In the areas of the fabric substrate where vias need to be formed to connect the circuits on both sides, a conductive paste is infiltrated into the texture structure of the fabric substrate at the areas using a gas pressure injection method, thereby connecting the corresponding areas of the fabric substrate from the front to the back, and the conductive paste is an intermetallic compound LM / Cu NP paste formed by mixing liquid metal and copper nanoparticles in a centrifugal mixer; 3) Forming conductive fabric lines and physiological electrodes: using a laser to cut the conductive fabric according to a pre-designed pattern to form conductive fabric lines and physiological electrodes, and then using a transfer method to transfer the conductive fabric lines and physiological electrodes to both sides of the fabric substrate, and the conductive fabric lines and physiological electrodes on both sides are connected through the vertical interconnection vias; 4) Integrating chip components: Welding chip components to conductive fabric lines using low melting point solder paste to form a complete circuit.

2. The formation of the laser-induced flexible sensor is specifically 2 The method for manufacturing the fabric hybrid electronic integrated system of claim 1, characterized in that it utilizes the photothermal effect of a laser or continuous green light with a wavelength of 532 nm to treat a precursor material on a fabric substrate or its surface according to a pre-designed pattern, induces a reaction of carbonization, phase separation or reduction sintering, and generates a laser-induced flexible sensor on one side of the fabric substrate for detecting physical and chemical signals on the body surface, and pulls the sensor out from the other side of the fabric substrate.

3. The method for manufacturing the fabric hybrid electronic integrated system of claim 1, characterized in that the manufacturing of the conductive fabric lines and physiological electrodes is a combination of laser cutting of the conductive fabric and transfer method, in which in the case of laser cutting, a water-soluble sacrificial layer is used to temporarily fix the conductive fabric lines and physiological electrodes, and after cutting is completed, the conductive fabric lines and physiological electrodes are transferred onto the fabric substrate, and finally the sacrificial layer is dissolved with water to avoid damage to the fabric substrate by the laser.

4. 10. The method for manufacturing the conductive fabric line and physiological electrodes according to claim 3, further comprising: laminating a layer of adhesive film (AL) on one side of a metal fabric (MT) and laminating a layer of water-soluble sacrificial layer (SL) on the other side of the metal fabric to form an AL / MT / SL structure; using an ultraviolet nanosecond laser to cut out a patterned conductive circuit from the two layers of AL and MT; leaving the SL intact; attaching the entire AL / MT / SL structure to a fabric substrate with the AL surface; immersing the fabric in water to remove the softened SL layer; drying the AL / MT layer attached to the fabric substrate; and peeling off the excess AL / MT layer other than the patterned conductive circuit to form a conductive fabric line or physiological electrode.

5. 2. The method for manufacturing a fabric hybrid electronic integrated system according to claim 1, wherein the low melting point solder paste is a paste obtained by mixing solder paste and aluminum flux.

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