A printing method of a liquid metal-based flexible electrode circuit

Abstract

The application belongs to the field of electronic circuit processing, and particularly relates to a printing method of a liquid metal-based elastic electrode circuit. The printing method of the liquid metal-based elastic electrode circuit comprises the following steps: obtaining a patterned elastic substrate; absorbing liquid metal with a sponge roller, and coating the elastic substrate with the sponge roller to obtain a liquid metal elastic electrode circuit. The application provides a mask-free printing method of a liquid metal elastic electrode circuit, adopts a sponge roller to extract and load liquid metal droplets, and obtains a patterned elastic substrate through laser etching, and the sponge roller is used for coating the liquid metal on the elastic substrate, thereby achieving interface adhesion enhancement effect, so as to ensure the yield rate after multiple stretching deformations.

Description

Technical Field

[0001] The invention belongs to the field of electronic circuit processing, and in particular relates to a printing method of an elastic electrode circuit based on liquid metal. Background Art

[0002] Liquid metal has deformable properties, but it is currently rarely used as circuit electrodes in flexible or stretchable devices. This is because the surface tension of liquid metal is too high, making it difficult to spread on solid surfaces, making large-scale patterning difficult. Moreover, after multiple stretching and deformation, the adhesion of liquid metal to the substrate weakens, causing electrode or circuit failure.

[0003] Existing technologies for fabricating liquid metal electrode circuits mostly employ methods such as ballpoint pen direct writing, inkjet printing, microfluidic channel printing, 3D printing, or mask printing. However, these methods (except mask printing) generally suffer from slow processing speeds and are not easily scalable for electrode circuit fabrication. Mask printing, on the other hand, is unsuitable for fabricating complex electrode circuits and requires a high level of mask preparation technology. Summary of the Invention

[0004] In view of the above-mentioned defects in the prior art, the object of the present invention is to provide a printing method of an elastic electrode circuit based on liquid metal, and in particular to provide a maskless printing method of an elastic electrode circuit based on liquid metal.

[0005] According to a specific embodiment of the present invention, a method for printing a liquid metal-based elastic electrode circuit includes the following steps:

[0006] (1) obtaining a patterned elastic substrate;

[0007] (2) Using a sponge roller to absorb the liquid metal, wherein the roller is covered with a sponge along its circumference to form the sponge roller, the thickness of the sponge is 5mm-5cm, and the density of the sponge is 18-45kg / cm 3 ;

[0008] (3) The elastic substrate is coated with a sponge roller to obtain a liquid metal elastic electrode circuit.

[0009] According to a specific embodiment of the present invention, a method for printing a liquid metal-based elastic electrode circuit is provided, wherein the liquid metal is Ga, GaIn alloy or GaInSn alloy.

[0010] Liquid metal has extremely high surface tension and easily forms an oxide film on its surface, making it difficult to adsorb uniformly on a solid surface on a large scale. This invention uses a sponge roller with uniform pores on its surface, allowing small liquid metal droplets to adsorb into these pores, achieving a filling effect. This can break up the existing oxidized surface and refine the liquid metal particles.

[0011] In the present application, the patterned elastic substrate can be obtained by a selective mask printing method or a laser etching method. The mask printing method can be completed by those skilled in the art according to the conventional technology in the art, and thus will not be described herein.

[0012] According to the printing method of the liquid metal-based elastic electrode circuit in the embodiment of the present application, in step (1), the step of laser etching the elastic substrate is included.

[0013] By laser etching the non-target area of the elastic substrate, the target area is obviously protruded from the surface of the elastic substrate, the sponge roller preferentially contacts the protruded position and has a greater force, and the printing and smearing effect is better.

[0014] According to the printing method of the liquid metal-based elastic electrode circuit in the embodiment of the present application, in step (1), the patterned elastic substrate is obtained by the following steps:

[0015] (1-1) preparing an elastic substrate and placing the elastic substrate on a hydrophobic substrate;

[0016] (1-2) laser etching the elastic substrate, the scanning speed of the laser is 50-300 mm / s, the power of the laser is 10-100 W, and the wavelength of the laser is 10.6 μm; that is, the required pattern is drawn by software and imported into a laser engraving machine, and the area other than the required pattern is selectively scanned and etched by using the laser, and the scanned part is ablated and gasified by the high-power laser;

[0017] (1-3) cleaning the elastic substrate after laser etching in step (1-2) to obtain a patterned elastic substrate;

[0018] Specifically, after laser etching, the surface of the substrate is cleaned with deionized water or alcohol and dried to remove residues. At this time, the required pattern part in the experiment will be obviously higher than other areas, in a convex state, and the patterned elastic substrate is prepared.

[0019] The present application specifically selects the elastic metal adsorbed by the sponge roller to cooperate with the elastic substrate to improve the interfacial adhesion effect and ensure the yield rate after multiple stretching deformations. First, a large number of liquid metal droplets are adsorbed on the surface of the sponge roller, and an oxide layer (for example, Ga2O3) is formed on the surface of the droplets in the air. The addition of a large number of oxide layers can greatly improve the adhesion of the liquid metal to the surface of the solid medium, and does not affect the electrical conductivity. In the printing process, the oxide layer first contacts the surface of the solid interface, improving the printing effect, and in repeated rolling printing, the liquid metal adhered to the surface of the solid medium re-forms an oxide layer, further enhancing the interfacial bonding force.

[0020] According to a specific embodiment of the present invention, a method for printing a liquid metal-based elastic electrode circuit, the elastic substrate is an acrylic tape, an elastic hydrogel film, a PDMS film or an Ecoflex film; and / or the hydrophobic substrate is a Parafilm film, a PET film, a PTFE film or a PI film.

[0021] According to a specific embodiment of the present invention, a method for printing elastic electrode circuits based on liquid metal is provided. In step (2), liquid metal is placed on a hard film substrate and a sponge roller is used to press the liquid metal. The liquid metal is uniformly adsorbed in the pores of the sponge.

[0022] According to a method for printing a liquid metal-based elastic electrode circuit according to a specific embodiment of the present invention, the material selected for the hard film substrate is PET, PVC or PI.

[0023] According to a specific embodiment of the present invention, a method for printing a liquid metal-based elastic electrode circuit further includes a step of packaging the liquid metal elastic electrode circuit.

[0024] According to a specific embodiment of the present invention, a printing method of a liquid metal-based elastic electrode circuit, the packaging method is a blade coating method or a spin coating method;

[0025] Preferably, the material selected for packaging is PDMS, Ecoflex or TPU.

[0026] Beneficial effects of the present invention:

[0027] The present invention provides a maskless printing method for liquid metal elastic electrode circuits. Liquid metal droplets are extracted and loaded with a sponge roller, which can realize the rapid preparation of large-scale liquid metal elastic electrode circuits. In addition, the present invention obtains a patterned elastic substrate through laser etching, and the sponge roller coats the liquid metal on the elastic substrate, which has the effect of enhancing interface adhesion, thereby ensuring the yield after multiple stretching deformations.

[0028] The method provided by the present invention has low preparation cost and is easy to operate. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0030] Figure 1A schematic diagram showing a process flow of the printing method of the present invention; wherein (1) a patterned elastic substrate is obtained; (2) liquid metal is sucked up with a sponge roller; (3) the sponge roller is applied to the elastic substrate;

[0031] 1-elastic substrate; 2-hydrophobic substrate; 3-laser; 4-hard film substrate; 5-sponge roller; 51-roller; 52-sponge; 53-liquid metal; 6-encapsulation layer; 11-patterned elastic substrate. DETAILED DESCRIPTION

[0032] To make the objectives, technical solutions, and advantages of the present invention more apparent, the technical solutions of the present invention will be described in detail below. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other implementations obtained by those of ordinary skill in the art without inventive effort are within the scope of protection of the present invention.

[0033] The present invention provides a maskless printing method for elastic electrodes or circuits based on liquid metal, which includes three main processes: Figure 1 As shown, they are elastic substrate patterned laser etching ( Figure 1-1 ), sponge roller absorbs liquid metal droplets ( Figure 1 -2) and rapid printing and coating of liquid metal elastic electrodes ( Figure 1 -3).

[0034] First, a patterned laser etching process for an elastic substrate is performed, including the following steps:

[0035] Step 1: Prepare a viscoelastic substrate (1), which can be made of acrylic tape, elastic hydrogel film, PDMS film, Ecoflex film, etc. Place the viscoelastic substrate on a hydrophobic substrate (2), which can be made of Parafilm, PET, PTFE, PI, etc.

[0036] Step 2: Draw the required pattern using software and import it into the laser engraving machine. Use laser (3) to selectively scan and etch the area outside the required pattern. The scanned part will be ablated and vaporized by high-power laser. The scanning speed is 50mm-300mm / s, the laser power is 10-100W, and the laser wavelength is 10.6μm.

[0037] Step 3: After the laser etching is completed, the substrate surface is cleaned with deionized water or alcohol and dried to remove the residue. At this point, the patterned portion required for the experiment will be significantly higher than other areas and will be in a convex state. The patterned elastic substrate (11) is now prepared.

[0038] Next, a process of using a sponge roller to absorb the liquid metal droplets is performed, including steps 4-6.

[0039] Step 4: Prepare a hard film substrate (4), which can be made of PET, PVC, PI, etc. Draw an appropriate amount of liquid metal (53) and drop it on the film substrate. The liquid metal composition can be Ga, GaIn alloy, GaInSn alloy, etc., and the composition ratio is not limited.

[0040] Step 5: Prepare a roller pressure wheel (51), and cover the roller with a layer of sponge (52) with a thickness of 5mm-5cm and a sponge density of 18-45Kg / cm 3 .

[0041] Step 6: Roll the sponge roller repeatedly with a certain force on the thin film substrate with liquid metal droplets so that the liquid metal droplets are evenly adsorbed in the gaps on the surface of the sponge roller.

[0042] Finally, the liquid metal elastic electrode is quickly printed and coated, including steps 7-8.

[0043] Step 7: Roll the sponge roller (5) that has absorbed the liquid metal droplets in step 6 repeatedly on the etched substrate and apply a certain force. At this point, the liquid metal droplets are evenly absorbed on the etched substrate, completing the patterning of the liquid metal elastic electrode circuit.

[0044] Step 8: Prepare the encapsulation layer (6) for the electrode circuit. The encapsulation material can be selected from highly elastic materials such as PDMS, Ecoflex, and TPU. The encapsulation method can be selected from blade coating or spin coating. After the encapsulation is completed, the substrate is peeled off, and the maskless printing preparation of the entire liquid metal elastic electrode or circuit is completed.

[0045] The printing method of the present invention is described below through specific embodiments.

[0046] Example 1

[0047] The printing method of the liquid metal-based elastic electrode circuit of the present invention comprises the following steps:

[0048] (1) obtaining a patterned elastic substrate;

[0049] (1-1) preparing an elastic substrate and placing the elastic substrate on a hydrophobic substrate, wherein the elastic substrate is an acrylic tape and the hydrophobic substrate is a Parafilm film;

[0050] (1-2) Laser etching the elastic substrate:

[0051] The required pattern is drawn by software and imported into the laser engraving machine. The laser is used to selectively scan and etch the area outside the required pattern. The scanned part will be ablated and vaporized by high-power laser. The scanning speed is 50mm / s, the laser power is 10W, and the laser wavelength is 10.6μm.

[0052] (1-3) After laser etching is completed, the substrate surface is cleaned and dried with deionized water or alcohol to remove residual steps, thereby obtaining a patterned elastic substrate;

[0053] (2) Use a sponge roller to absorb the liquid metal, wherein,

[0054] The roller is covered with sponge along its circumference to form the sponge roller. The thickness of the sponge is 5 mm and the density of the sponge is 18 kg / cm 3 ,

[0055] The liquid metal Ga is placed on a hard film substrate (made of PET, PVC or PI), and a sponge roller is used to press the liquid metal onto the sponge. The liquid metal is evenly adsorbed on the sponge.

[0056] Roll the sponge roller repeatedly on the hard film substrate with the liquid metal droplet, applying force at an angle of 30° to 60° and a force range of 1N to 10N, so that the liquid metal droplets are evenly adsorbed in the gaps on the surface of the sponge roller;

[0057] (3) applying a force at an angle of 30° to 60° and a force range of 1N to 10N by brushing the elastic substrate with a sponge roller to obtain a liquid metal elastic electrode circuit;

[0058] (4) Encapsulating the electrode circuit. The encapsulation material can be selected from highly elastic materials such as PDMS, Ecoflex, and TPU. The encapsulation method can be selected from blade coating or spin coating. After encapsulation is completed, the substrate is peeled off, completing the maskless printing preparation of the entire liquid metal elastic electrode or circuit.

[0059] Example 2

[0060] The method for printing a liquid metal elastic electrode circuit of the present invention comprises the following steps:

[0061] (1) obtaining a patterned elastic substrate;

[0062] (1-1) preparing an elastic substrate and placing the elastic substrate on a hydrophobic substrate, wherein the elastic substrate is an elastic hydrogel film and the hydrophobic substrate is a PET film;

[0063] (1-2) Laser etching the elastic substrate:

[0064] The required pattern is drawn by software and imported into the laser engraving machine. The laser is used to selectively scan and etch the area outside the required pattern. The scanned part will be ablated and vaporized by high-power laser. The scanning speed is 150mm / s, the laser power is 50W, and the laser wavelength is 10.6μm.

[0065] (1-3) After laser etching is completed, the substrate surface is cleaned and dried with deionized water or alcohol to remove residual steps, thereby obtaining a patterned elastic substrate;

[0066] (2) Use a sponge roller to absorb the liquid metal, wherein,

[0067] The roller is covered with sponge along its circumference to form the sponge roller. The thickness of the sponge is 2 cm and the density of the sponge is 20 kg / cm 3 ,

[0068] Liquid metal Ga, GaIn alloy, or GaInSn alloy is placed on a hard film substrate (made of PET, PVC, or PI). A sponge roller is repeatedly rolled on the hard film substrate with the liquid metal applied at an angle of 30° to 60° and a force range of 1N to 10N, so that the liquid metal droplets are evenly adsorbed in the gaps on the surface of the sponge roller.

[0069] (3) applying a force at an angle of 30° to 60° and a force range of 1N to 10N by brushing the elastic substrate with a sponge roller to obtain a liquid metal elastic electrode circuit;

[0070] (4) Encapsulating the electrode circuit. The encapsulation material can be selected from highly elastic materials such as PDMS, Ecoflex, and TPU. The encapsulation method can be selected from blade coating or spin coating. After encapsulation is completed, the substrate is peeled off, completing the maskless printing preparation of the entire liquid metal elastic electrode or circuit.

[0071] Example 3

[0072] The method for printing a liquid metal elastic electrode circuit of the present invention comprises the following steps:

[0073] (1) obtaining a patterned elastic substrate;

[0074] (1-1) An elastic substrate is prepared and placed on a hydrophobic substrate, wherein the elastic substrate is a PDMS membrane and the hydrophobic substrate is a PTFE membrane.

[0075] (1-2) Laser etching the elastic substrate:

[0076] The required pattern is drawn by software and imported into the laser engraving machine. The laser is used to selectively scan and etch the area outside the required pattern. The scanned part will be ablated and vaporized by high-power laser. The scanning speed is 300mm / s, the laser power is 100W, and the laser wavelength is 10.6μm.

[0077] (1-3) After laser etching is completed, the substrate surface is cleaned and dried with deionized water or alcohol to remove residual steps, thereby obtaining a patterned elastic substrate;

[0078] (2) Use a sponge roller to absorb the liquid metal, wherein,

[0079] The roller is covered with sponge along its circumference to form the sponge roller. The thickness of the sponge is 5 cm and the density of the sponge is 45 kg / cm 3 ,

[0080] Liquid metal GaInSn alloy is placed on a hard film substrate (made of PET, PVC, or PI). A sponge roller is repeatedly rolled on the film substrate with the liquid metal droplet at an angle of 30° to 60° and a force range of 1N to 10N, so that the liquid metal droplets are evenly adsorbed in the gaps on the surface of the sponge roller.

[0081] (3) applying a force at an angle of 30° to 60° and a force range of 1N to 10N by brushing the elastic substrate with a sponge roller to obtain a liquid metal elastic electrode circuit;

[0082] (4) Encapsulating the electrode circuit. The encapsulation material can be selected from highly elastic materials such as PDMS, Ecoflex, and TPU. The encapsulation method can be selected from blade coating or spin coating. After encapsulation is completed, the substrate is peeled off, completing the maskless printing preparation of the entire liquid metal elastic electrode or circuit.

[0083] Comparative Example 1

[0084] Compared with Example 1, the material of the elastic base is selected as styrene-butadiene rubber, and the other components, proportions, and steps are the same as those of Example 1.

[0085] Comparative Example 2

[0086] Compared with Example 1, the material included outside the roller is selected as wool felt with a thickness of 5 mm, and the other components, proportions, and steps are the same as those in Example 1.

[0087] Comparative Example 3

[0088] Compared with Example 1, the parameters of the sponge wrapped around the roller are thickness 1 cm, density 5 kg / cm 3 , the other steps are the same as those in Example 1.

[0089] Comparative Example 4

[0090] Compared with Example 1, the parameters of laser etching are scanning speed 150 mm / s, laser power 5 W, and laser wavelength 10.6 μm; other steps are the same as Example 1.

[0091] The samples of Examples 1-3 and Comparative Examples 1-4 were selected and tested according to the following method: GaInSn liquid metal was used to print 10cm 2Target substrate, printing force 2N, angle 45 degrees, repeated roll coating 10 times. Observe the surface morphology and density; laser etch the target area of the elastic substrate 5cm*1cm, test the conductivity of the target area and non-target area; after stretching and retracting the target area 500 times (maximum strain 200%), test the conductivity of the target area.

[0092] The test results are shown in Table 1:

[0093] Table 1 printing test results

[0094]

[0095]

[0096] As can be seen from Table 1, the samples of Examples 1-3 of the present application, 10cm 2 After large-area printing, the surface is dense, there is no missing, the 5cm*1cm target area is conductive, the non-target area is open circuit, the electrode circuit patterning effect is achieved, the conductivity of the target area is good after 500 cycles of stretching, and the experimental results show that the implementation conditions selected in Examples 1-3 can well realize the maskless printing effect of the elastic electrode circuit based on liquid metal.

[0097] In Comparative Example 1, after the material of the elastic substrate is selected as styrene-butadiene rubber, 10cm 2 After large-area printing, the surface has obvious areas that are not printed, resulting in non-conductive target areas, and the experimental results show that the styrene-butadiene rubber substrate cannot realize the maskless printing effect of the elastic electrode circuit based on liquid metal.

[0098] In Comparative Example 2, after the material wrapped outside the roller is selected as wool felt, 10cm 2 After large-area printing, the surface is almost entirely unprinted, resulting in non-conductive target areas, and the experimental results show that the wool felt wrapped outside the roller cannot realize the maskless printing effect of the elastic electrode circuit based on liquid metal.

[0099] In Comparative Example 3, the thickness of the sponge wrapped outside the roller is changed to 2cm density After the change, 10cm 2 After large-area printing, the surface is dense, there is no missing, the 5cm*1cm target area is conductive, the non-target area is conductive, and the electrode circuit patterning effect is not achieved, and the experimental results show that the sponge wrapped outside the roller with a thickness of 1cm and a density of 5Kg / cm 3 cannot realize the maskless printing effect of the elastic electrode circuit based on liquid metal.

[0100] In Comparative Example 4, after the parameters of laser etching are changed, 10cm 2After large-area printing, the surface is dense and without defects, the 5cm*1cm target area is conductive, and the non-target area is conductive, but the electrode circuit patterning effect is not achieved. The experimental results show that after the laser etching parameters are changed, the maskless printing effect of the liquid metal elastic electrode circuit cannot be achieved.

[0101] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A method for printing elastic electrode circuits based on liquid metal, characterized in that: The printing method comprises the following steps: (1) Obtaining a patterned elastic substrate: (1-1) Preparing an elastic substrate and placing the elastic substrate on a hydrophobic substrate; (1-2) laser etching the elastic substrate, using a laser to selectively scan and etch areas outside the desired pattern, wherein the scanned area is ablated and vaporized by a high-power laser, with a laser scanning speed of 50 mm to 300 mm / s, a laser power of 10 to 100 W, and a laser wavelength of 10.6 μm; (1-3) Cleaning the elastic substrate after laser etching in step (1-2), thereby obtaining a patterned elastic substrate, wherein the desired pattern portion is higher than other regions and is in a convex state; The elastic substrate is an acrylic tape, an elastic hydrogel film, a PDMS film or an Ecoflex film; and / or the hydrophobic substrate is a Parafilm film, a PET film, a PTFE film or a PI film; (2) Using a sponge roller to absorb liquid metal, wherein the roller is covered with sponge along its circumference to form the sponge roller, the thickness of the sponge is 5mm-5cm, and the density of the sponge is 18-45kg / cm 3 ; (3) The elastic substrate is coated with a sponge roller to obtain a liquid metal elastic electrode circuit.

2. The method for printing a liquid metal-based elastic electrode circuit according to claim 1, characterized in that: The liquid metal is Ga, GaIn alloy or GaInSn alloy.

3. The method for printing a liquid metal-based elastic electrode circuit according to claim 1, wherein: In step (2), the liquid metal is placed on a hard film substrate, and a sponge roller is used to press the liquid metal, so that the liquid metal is uniformly adsorbed in the pores of the sponge.

4. The method for printing a liquid metal-based elastic electrode circuit according to claim 3, characterized in that: The material of the hard film substrate is PET, PVC or PI.

5. The method for printing a liquid metal-based elastic electrode circuit according to claim 3, wherein: The method also includes the step of packaging the liquid metal elastic electrode circuit.

6. The method for printing a liquid metal-based elastic electrode circuit according to claim 5, characterized in that: The encapsulation method is blade coating or spin coating; and / or the material selected for encapsulation is PDMS, Ecoflex or TPU.

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