Ionic wind-assisted electrostatic printing nozzle structure and method for micro-nano structure on surface of insulating substrate

Abstract

The invention discloses an ionic wind-assisted electrostatic printing nozzle structure and method for a micro-nano structure on the surface of an insulating substrate. The electrostatic printing nozzle structure comprises an electrostatic printing nozzle, and the outer side of the electrostatic printing nozzle is coaxially connected with an ionic wind generation module; an inlet in the upper part of the electrostatic printing nozzle is connected with a driving pneumatic source; a nozzle at the bottom of the electrostatic printing nozzle is connected with a high-voltage power supply; an ionization electrode is arranged in the ion wind generation module, positive and negative ions are generated after high voltage is applied, ion wind is formed through airflow driving and focused in a printing area below the nozzle, the surface of the insulating substrate is always in an approximate zero potential state, and a virtual grounding electrode is formed; according to the method, the virtual grounding electrode is constructed on the insulating surface by using the ionic wind, so that the problem of unstable electric field in the printing process caused by printing height change and charge accumulation on the insulating surface is solved, and the applicability of electrostatic printing to an insulating material target substrate is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of electrostatic printing, and in particular to an ion wind-assisted electrostatic printing nozzle structure and method for micro-nanostructure electrostatic printing on an insulating substrate surface. Background Art

[0002] Electrostatic printing technology is a micro-nano additive manufacturing technology based on electrohydrodynamic traction ink jet deposition. It applies a high voltage of thousands of volts to the nozzle to form a strong electric field between the nozzle and the grounded receiving substrate. The electric field force is used to "pull" the ink out of the nozzle to form a Taylor cone, producing a jet much smaller than the nozzle diameter. It can print micro-nano structures with high resolution and controllable properties, and has broad application prospects in micro-nano electronics, biological tissue engineering, etc.

[0003] In the existing electrostatic printing technology, a method of applying periodic pulsed AC voltage and introducing electrode rings (patent application entitled "In-line electrofluid printing nozzle and printing method capable of suppressing jet interference", publication number: CN112644178B) and electrostatic lenses (patent application entitled "An electrostatic focusing electrofluid printing device and method", publication number: CN109532242B) to form a gradient electric field is often used to enhance the electric field strength between the nozzle and the receiving substrate and improve the stability of electrostatic printing, but this method is difficult to work on an insulating curved substrate with a large thickness variation. There is also a patent (patent application entitled "An electric field-flow field mixed control electrofluid printing method and device", publication number: CN108340681B) to form a focused stable fluid flow field below the nozzle to overcome the problem that conventional electrofluid printing cannot be printed on an insulating substrate or a free-form substrate, but this method does not essentially eliminate the influence of residual charge. There are also patents (patent application entitled "A sheet plasma driven arrayed electrofluid printing device and method", publication number: CN116198221B; patent application entitled "A plasma-based anti-crosstalk arrayed electrofluid printing device and method", publication number: CN115972769B) that propose a plasma-driven electrofluid printing method, which uses alternating positive and negative plasma generated by applying a pulse voltage to bombard the target surface, charge the insulating substrate to form an electric field, and realize electrostatic printing on the insulating substrate. This method effectively avoids the problem of residual charge generation, but the alternating changes in positive and negative voltages will cause fluctuations in the electric field strength, affecting the stability of the Taylor cone.

[0004] In summary, due to the limitation of high-voltage electric field, it is difficult for electrostatic printing to stably print on thick insulating substrates or insulating substrates with large surface profile height changes: on the one hand, the electric field strength decreases with the increase of the distance between the nozzle and the grounded substrate, and it is impossible to provide sufficient electric field traction for electrostatic printing; on the other hand, the charge induced by the nozzle connected to the high voltage and the residual charge inside the deposited ink will accumulate on the insulating surface and cannot be transferred, causing electrostatic repulsion of the ink in subsequent printing, affecting the continuity of electrostatic printing. Summary of the invention

[0005] In order to overcome the shortcomings of the above-mentioned prior art, the purpose of the present invention is to provide an ion wind-assisted insulating substrate surface micro-nanostructure electrostatic printing nozzle structure and method, which utilizes ion wind to construct a virtual ground electrode on the insulating surface, solves the problem of electric field instability during printing due to changes in printing height and charge accumulation on the insulating surface, and improves the applicability of electrostatic printing to target substrates of insulating materials.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] The invention discloses an ion wind assisted insulating substrate surface micro-nano structure electrostatic printing nozzle structure, comprising an electrostatic printing nozzle 1, wherein the outer side of the electrostatic printing nozzle 1 is coaxially connected to an ion wind generating module 2; an inlet at the upper part of the electrostatic printing nozzle 1 is connected to a driving air pressure source 101, and a nozzle 102 at the bottom of the electrostatic printing nozzle 1 is connected to a high voltage power supply 103; the ion wind generating module 2 has an internal ionization electrode 201, which generates positive and negative ions after high voltage is applied, and is driven by airflow to form ion wind, which is focused in the printing area below the nozzle 102, so that the surface of the insulating substrate 3 is always in a state of approximately zero potential, forming a virtual ground electrode.

[0008] The nozzle 102 is a conductive nozzle, and a stainless steel needle or a gold-plated glass needle is selected; the outer layer of the nozzle 102 is coated with an insulating material, and the insulating material is selected from rubber or silicone.

[0009] The electrostatic printing nozzle 1 is filled with functional ink 104, which is a conductive functional ink containing metal nanoparticles of gold, silver, and copper, or a sensing functional ink containing nanomaterials of carbon nanotubes, silver nanowires, and MXene.

[0010] An air flow inlet 202 is provided at the top of the ion wind generating module 2, an ionization electrode 201 is connected inside, and an air flow outlet 203 is provided at the bottom; more than two ionization electrodes 201 are connected inside the ion wind generating module 2, and the ionization electrodes 201 are coaxially evenly distributed in a ring around the central electrostatic printing nozzle 1, and the applied high voltage is in the form of AC or positive and negative DC, with an amplitude range of 1kV-50kV, and an AC frequency of 1Hz-1000Hz; an air flow inlet 202 is provided between every two ionization electrodes 201, and the air flow enters the ion wind generating module 2 from the air flow inlet 202, and the ion wind is blown out from the air flow outlet 203, and the gas introduced is air, nitrogen or argon.

[0011] The flow channel of the airflow outlet 203 is inclined inwardly at an angle of 15°-75°, focusing on the nozzle 102 so that the blown ion wind is gathered in the printing area; the airflow outlet 203 is not less than 30 mm away from the nozzle 102.

[0012] The insulating substrate 3 is a flat substrate or a curved substrate, and is made of glass, plastic, silicone rubber, paper or fabric. The height of the insulating substrate 3 from the bottom surface ranges from 1 mm to 1 m.

[0013] The electrostatic printing nozzle 1 and the ion wind generating module 2 are installed on a motion module with three axes or more or a multi-axis robot arm.

[0014] The method for electrostatically printing a nozzle structure of a micro-nanostructure on an insulating substrate surface using the ion wind-assisted method comprises the following steps:

[0015] 1) Adjust the position of the electrostatic printing nozzle 1 along the Z direction so that the nozzle 102 is in the focusing area of ​​the ion wind, and fix the relative position of the electrostatic printing nozzle 1 and the ion wind generating module 2;

[0016] 2) Turn on the ion wind generating module 2, introduce airflow, blow out ion wind containing positive and negative ions, so that a virtual ground electrode is formed in the printing area on the surface of the insulating substrate 3;

[0017] 3) Turn on the driving air pressure source 101, and the functional ink 104 is extruded from the nozzle 102. When the extrusion flow rate is stable, set the printing process parameters;

[0018] 4) Turn on the high voltage power supply 103, apply a high voltage to the nozzle 102 in a high potential state, and form a stable electric field between the nozzle 102 and the virtual ground electrode on the surface of the insulating substrate 3. The functional ink 104 is pulled by the electric field force to form a Taylor cone and is deposited on the insulating substrate 3;

[0019] 5) The electrostatic printing nozzle 1 and the ion wind generating module 2 move along a preset printing trajectory, and the ion wind generating module 2 continuously blows out ion wind to maintain the virtual grounding state of the target surface of the insulating substrate 3, thereby ensuring stable electrostatic printing on the insulating surface.

[0020] The printing process parameters of step 3) include applied voltage, platform moving speed, printing receiving distance, driving air pressure and ion wind speed.

[0021] Compared with the prior art, the advantages of the present invention are:

[0022] 1. The present invention breaks through the limitation of electrostatic printing on the height of the insulating substrate. It can use ion wind to assist in constructing a virtual ground electrode on the surface of the insulating substrate at any height, so that a stable electric field is formed between the surface of the insulating substrate and the nozzle. The electric field strength will depend on the voltage value applied at the nozzle, and there is no need to dynamically adjust the voltage according to the height of the insulating substrate. The virtual ground electrode can be formed on the target surface of any shape, greatly improving the stability and printing resolution of electrostatic printing on curved insulating surfaces.

[0023] 2. The present invention reduces the requirements for the applied voltage value for electrostatic printing on the surface of the insulating substrate, and can effectively eliminate residual charges. On the insulating substrate, compared with conventional electrostatic printing, which requires the application of several thousand volts of voltage to form a strong electric field to provide sufficient electric field traction, the present invention can reduce the required voltage value to 1 / 4 to 1 / 3 of conventional electrostatic printing, greatly improving the safety during the printing process. At the same time, the reduction in applied voltage also reduces the residual charge induced or accumulated on the surface of the insulating substrate, which is conducive to reducing the charge repulsion phenomenon during electrostatic printing.

[0024] 3. The coaxial design of the ion wind generating device of the present invention ensures the consistency of the virtual grounding state of the printing area near the nozzle, especially for electrostatic printing on curved surfaces, which can make the ion wind blow evenly on insulating curved surfaces of any shape, while minimizing motion interference during the printing process. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of an ion wind-assisted insulating substrate surface micro-nanostructure electrostatic printing nozzle structure of the present invention.

[0026] Figure 2 It is a schematic diagram of the ion wind generating module of the present invention.

[0027] Figure 3 It is a physical comparison diagram of printing a conductor on a flat insulating surface with a height of 50 mm by an ion wind-assisted electrostatic printing method according to an embodiment of the present invention and a conventional electrostatic printing method.

[0028] Figure 4This is a physical picture of the printing effect of the ion wind-assisted electrostatic printing method of an embodiment of the present invention on a flat insulating surface with a height of 100 mm.

[0029] Figure 5 This is a physical picture of the conduction effect of printing a wire on the surface of a planar insulating substrate according to an embodiment of the present invention.

[0030] Figure 6 This is a physical picture of printing a spiral conductor on the surface of a curved insulating substrate according to an embodiment of the present invention. DETAILED DESCRIPTION

[0031] The present invention will be further described below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0032] Reference Figure 1 , Figure 2 The invention discloses an ion wind assisted insulating substrate surface micro-nano structure electrostatic printing nozzle structure, comprising an electrostatic printing nozzle 1, the outer side of the electrostatic printing nozzle 1 is coaxially connected with an ion wind generating module 2, and the electrostatic printing nozzle 1 is fixed by the ion wind generating module 2; the inlet at the upper part of the electrostatic printing nozzle 1 is connected with a driving air pressure source 101, and the nozzle 102 at the bottom of the electrostatic printing nozzle 1 is connected with a high voltage power supply 103; the ion wind generating module 2 has an ionized electrode 201 built in, which generates positive and negative ions after high voltage is applied, and ion wind is formed by airflow and focused in the printing area below the nozzle 102, so that the surface of the insulating substrate 3 is always in a state of approximately zero potential, forming a virtual ground electrode.

[0033] The nozzle 102 is a conductive nozzle, and a stainless steel needle, a gold-plated glass needle, etc. can be selected. The excellent conductivity makes the nozzle 102 at the same electric potential everywhere; the outer layer of the nozzle 102 is coated with an insulating material, and rubber, silicone, etc. can be selected to prevent the nozzle 102 from absorbing too many charged ions; the nozzle 102 provides an electric field driving force for electrostatic printing after applying a positive or negative high voltage, pulling the functional ink to form a Taylor cone, and the high voltage amplitude selection range is 0.5-5kV.

[0034] The electrostatic printing nozzle 1 is filled with functional ink 104, which can be a conductive functional ink containing metal nanoparticles such as gold, silver, and copper, or a sensing functional ink containing nanomaterials such as carbon nanotubes, silver nanowires, and MXene, for electronic circuit printing; in this embodiment, a conductive ink containing silver nanoparticles is selected.

[0035] Reference Figure 2 The ion wind generating module 2 has an airflow inlet 202 at the top, an ionization electrode 201 connected inside, and an airflow outlet 203 at the bottom;

[0036] The ion wind generating module 2 of the present embodiment has eight built-in ionization electrodes 201, which are coaxially and evenly distributed in a ring shape around the central electrostatic printing nozzle 1. The number and arrangement of the ionization electrodes 201 can be flexibly selected according to needs; after 15kV alternating current is applied to the ionization electrode 201, corona discharge occurs at the tip thereof to generate air ions with positive and negative charges, and an air flow inlet 202 is provided between every two ionization electrodes 201, and the air flow flows into the ion wind generating module 2 to form ion wind, and the gas introduced can be air, nitrogen, argon, etc.; the position of the ionization electrode 201 is close to the air flow outlet 203 at the bottom of the ion wind generating module 2, which can reduce the kinetic energy lost along the flow path of the ion wind and the amount of positive and negative ions.

[0037] The flow channel of the air flow outlet 203 is inclined inwardly at an angle of 15°-75°, focusing on the nozzle 102 so that the blown ion wind is gathered in the printing area; the air flow outlet 203 is not less than 30 mm away from the nozzle 102.

[0038] The insulating substrate 3 is a flat substrate or a curved substrate with varying heights. The substrate material may be glass, plastic, silicone rubber, paper, fabric, etc. The height of the insulating substrate 3 surface from the bottom surface ranges from 1 mm to 1 m.

[0039] The electrostatic printing nozzle 1 and the ion wind generating module 2 are installed on a three-axis motion module, and a motion module with three or more axes or a multi-axis robot arm can also be selected according to printing requirements.

[0040] The method for electrostatically printing a nozzle structure of a micro-nanostructure on an insulating substrate surface using the ion wind-assisted method comprises the following steps:

[0041] 1) Adjust the position of the electrostatic printing nozzle 1 along the Z direction up and down so that its nozzle 102 is in the focusing area of ​​the ion wind, ensuring that the target printing area is within the range reached by the ion wind, and then fix the relative position of the electrostatic printing nozzle 1 and the ion wind generating module 2;

[0042] 2) Turn on the ion wind generating module 2, and the annularly distributed ionizing electrodes 201 ionize the air inside the ion wind generating module 2 into air ions with positive and negative charges through corona discharge, and then introduce air, and the ion wind containing positive and negative ions is blown out evenly from the air flow outlet 203 flow channel, and the ion wind can neutralize the surface of the insulating substrate 3 with positive or negative electrostatic charges to a state close to zero potential, thereby forming a virtual ground electrode in the target printing area;

[0043] The flat insulating substrate selected in this embodiment is a plastic cube with a height of 50 mm and 100 mm. The cube is printed by a 3D printer fuse. The printing filament is PLA material, and then soaked in a polishing liquid to eliminate the surface layer lines; the curved insulating substrate selected in this embodiment is a hollow hemispherical model with a ball diameter of 65 mm, corresponding to a curvature of 30.85 mm. -1 ,The hemispherical model was manufactured by a photo-curing printer and the material was resin;

[0044] 3) Turn on the driving air pressure source 101, and the functional ink 104 filled in the electrostatic printing nozzle 1 is extruded from the nozzle 102 under the air pressure drive. When the extrusion flow rate is stable, set the printing process parameters, including the applied voltage of 1500V, the platform moving speed of 5mm / s, the printing receiving distance of 400μm, the driving air pressure of 1500mbar, and the ion wind speed of 0.2m / s;

[0045] 4) Turn on the high voltage power supply 103, apply a high voltage to the nozzle 102 in a high potential state, and form a stable electric field between the nozzle 102 and the virtual ground electrode on the surface of the insulating substrate 3. The functional ink 104 is pulled by the electric field force in the electric field to form a Taylor cone and is deposited downward on the insulating substrate 3;

[0046] 5) According to the preset printing path, the electrostatic printing nozzle 1 and the ion wind generating module 2 will move along the set trajectory. The printing trajectory selected in this embodiment is a planar peano curve. During the movement, the functional ink 104 is pulled by the electric field force to continuously deposit downward to form a conductive circuit; at the same time, the ion wind generating module 2 continuously blows out ion wind, continuously eliminating the residual charge generated on the target surface of the insulating substrate 3, maintaining its virtual grounding state, so that the potential difference between the surface of the insulating substrate 3 and the nozzle 102 maintains a dynamic balance, thereby achieving a stable electrostatic printing effect.

[0047] Reference Figure 3 , Figure 3 This is a physical comparison diagram of the electrostatic printing method of this embodiment and the conventional electrostatic printing method (without ion wind) printing the wire on the surface of a flat insulating substrate with a height of 50 mm. It can be seen that under the condition of ion wind assistance, the peano wire printed on the surface of the flat insulating substrate is overall uniform and continuous, indicating that the electric field constructed between the nozzle 102 and the virtual ground electrode on the surface of the insulating substrate 3 according to the electrostatic printing method of the present invention is very stable and can achieve the expected printing effect; in contrast, under the condition of no ion wind assistance and the same other process parameters, the electrostatic printing cannot remain stable on the surface of the flat insulating substrate, and the printed peano wire has a large area of ​​serious disconnection or the material cannot be deposited. It can be seen that the electrostatic printing method of the present invention can effectively solve the problem that electrostatic printing cannot be stably performed on the insulating surface.

[0048] Reference Figure 4, Figure 4 This is a physical picture of the printing effect of the ion wind-assisted micro-nano structure electrostatic printing method of this embodiment on the surface of a planar insulating substrate with a height of 100 mm. It can be seen that, referring to the electrostatic printing method of the present invention, complex peano wires can be stably printed on a planar insulating substrate of a large height, indicating that the method of the present invention can effectively break through the limitation of the substrate height on electrostatic printing and realize continuous and stable electrostatic printing on a large height insulating surface.

[0049] Reference Figure 5 , Figure 5 This is a physical picture of the conductive effect of printing the wire on the surface of the planar insulating substrate in this embodiment. The conductivity of the peano wire printed on the surface of the planar insulating substrate with a height of 50 mm was tested. The wire is continuous and conductive as a whole, and the measured resistance is 1.05kΩ.

[0050] Reference Figure 6 , Figure 6 This is a spiral conductor printed on the surface of a curved insulating substrate in this embodiment. It can be seen that, referring to the electrostatic printing method of the present invention, a micro-scale conformal circuit structure can be stably printed on a hollow hemispherical surface. From the microscopic diagram, it can be seen that the spiral lines printed at different heights on the hemispherical surface can maintain good continuity. It can be seen that the electrostatic printing method of the present invention can be effectively extended to the scope of curved insulating surfaces.

[0051] As described above, the embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some of the technical features therein by equivalents. These modifications or replacements do not deviate the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention. Therefore, all other embodiments obtained by those skilled in the art without making creative efforts belong to the protection scope of the present invention.

Claims

1. An ion wind-assisted insulating substrate surface micro-nano structure electrostatic printing nozzle structure, characterized in that: The invention comprises an electrostatic printing nozzle (1), wherein the outer side of the electrostatic printing nozzle (1) is coaxially connected to an ion wind generating module (2); an inlet at the top of the electrostatic printing nozzle (1) is connected to a driving air pressure source (101), and a nozzle (102) at the bottom of the electrostatic printing nozzle (1) is connected to a high voltage power supply (103); the ion wind generating module (2) has a built-in ionization electrode (201), which generates positive and negative ions after a high voltage is applied, and is driven by an airflow to form an ion wind, which is focused in a printing area below the nozzle (102), so that the surface of the insulating substrate (3) is always in a state of approximately zero potential, forming a virtual ground electrode.

2. The ion wind-assisted insulating substrate surface micro-nano structure electrostatic printing nozzle structure according to claim 1, characterized in that: The nozzle (102) is a conductive nozzle, and a stainless steel needle or a gold-plated glass needle is selected; the outer layer of the nozzle (102) is coated with an insulating material, and the insulating material is selected from rubber or silicone.

3. The ion wind-assisted insulating substrate surface micro-nano structure electrostatic printing nozzle structure according to claim 1, characterized in that: The electrostatic printing nozzle (1) is filled with functional ink (104), which is a conductive functional ink containing metal nanoparticles of gold, silver, and copper, or a sensing functional ink containing nanomaterials such as carbon nanotubes, silver nanowires, and MXene.

4. The ion wind-assisted insulating substrate surface micro-nano structure electrostatic printing nozzle structure according to claim 1, characterized in that: The ion wind generating module (2) is provided with an airflow inlet (202) at the top, is internally connected with an ionization electrode (201), and is provided with an airflow outlet (203) at the bottom; the ion wind generating module (2) is internally connected with more than two ionization electrodes (201), and the ionization electrodes (201) are coaxially evenly distributed in a ring around the central electrostatic printing nozzle (1), and the applied high voltage is in the form of alternating current or positive and negative direct current, with an amplitude range of 1kV-50kV, and an alternating current frequency of 1Hz-1000Hz; an airflow inlet (202) is provided between every two ionization electrodes (201), and the airflow enters the ion wind generating module (2) from the airflow inlet (202), and the ionized wind is blown out from the airflow outlet (203), and the introduced gas is air, nitrogen or argon.

5. The ion wind-assisted insulating substrate surface micro-nano structure electrostatic printing nozzle structure according to claim 4, characterized in that: The flow channel of the airflow outlet (203) is inclined inwardly at an angle of 15°-75°, focusing on the nozzle (102) so that the blown ion wind is gathered in the printing area; the airflow outlet (203) is not less than 30 mm away from the nozzle (102).

6. The ion wind assisted insulating substrate surface micro-nano structure electrostatic printing nozzle structure according to claim 1, characterized in that: The insulating substrate (3) is a flat substrate or a curved substrate, and is made of glass, plastic, silicone rubber, paper or fabric. The height between the surface of the insulating substrate (3) and the bottom surface ranges from 1 mm to 1 m.

7. The ion wind-assisted insulating substrate surface micro-nano structure electrostatic printing nozzle structure according to claim 1, characterized in that: The electrostatic printing nozzle (1) and the ion wind generating module (2) are installed on a motion module with three or more axes or a multi-axis mechanical arm.

8. A method for electrostatically printing a nozzle structure of a micro-nano structure on an insulating substrate surface using an ion wind-assisted method as claimed in any one of claims 1 to 7, characterized in that: The following steps are involved: 1) adjusting the position of the electrostatic printing nozzle (1) along the Z direction so that the nozzle (102) is located in the focusing area of ​​the ion wind, and fixing the relative position of the electrostatic printing nozzle (1) and the ion wind generating module (2); 2) turning on the ion wind generating module (2), introducing airflow, blowing out ion wind containing positive and negative ions, so that a virtual ground electrode is formed in the printing area on the surface of the insulating substrate (3); 3) Turning on the driving air pressure source (101), the functional ink (104) is extruded from the nozzle (102), and when the extrusion flow rate is stable, setting the printing process parameters; 4) Turning on the high voltage power supply (103), applying a high voltage to the nozzle (102) to be in a high potential state, forming a stable electric field between the nozzle (102) and the virtual ground electrode on the surface of the insulating substrate (3), and the functional ink (104) is pulled by the electric field force to form a Taylor cone and deposited on the insulating substrate (3); 5) The electrostatic printing nozzle (1) and the ion wind generating module (2) move along a preset printing trajectory, and the ion wind generating module (2) continuously blows out ion wind to maintain the virtual grounding state of the target surface of the insulating substrate (3), thereby ensuring stable electrostatic printing on the insulating surface.

9. The method according to claim 8, characterized in that: The printing process parameters of step 3) include applied voltage, platform moving speed, printing receiving distance, driving air pressure and ion wind speed.

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