Method for preparing micro-channel array in transparent material by low-power laser

Abstract

The invention provides a method for preparing a micro-channel array in a transparent material through low-power laser. The method comprises the steps that the transparent material is preheated; a target material is arranged on the workbench, and the transparent material is tightly arranged above the target material; the low-power laser is adjusted to be perpendicular to the transparent material for incidence, and the laser focus is adjusted on the interface of the transparent material and the target material; setting the scanning speed and the scanning distance of the low-power laser according to the inclination angle of the micro-channel array and the distance between adjacent micro-channels; a micro-cavity is ablated on the lower surface of the transparent material by plasmas induced by the low-power laser from the target material, and the plasmas are limited in the micro-cavity; and performing scanning by using low-power laser, and keeping a laser focus on the interface in the scanning process so as to obtain the micro-channel with an adjustable inclination angle. According to the method, the target material is introduced, low-power laser is used for inducing plasma to assist ablation, the angle-adjustable micro-channel array can be prepared in the transparent material, energy consumption can be saved, and the production cost can be reduced.

Description

Technical Field

[0001] The invention relates to the technical field of microchannel preparation, and more specifically to a method for preparing a microchannel array inside a transparent material using a low-power laser. Background Art

[0002] A microchannel is a channel structure with a micrometer scale, and its size range is usually between 10 micrometers and 1000 micrometers. The application fields of microchannels are very wide. For example, in the biomedical field, microfluidic chips can be prepared for the detection, separation, extraction, and analysis of biological samples such as DNA, RNA, and protein. In the chemical field, flow catalysts can be prepared, and microchannel reactors can be used for reaction synthesis to prepare various compounds. In the mechanical manufacturing field, micromechanical components such as micropumps, microvalves, microwaves, and microheaters can be prepared. In the optical field, photonic crystals can be prepared for use in sensing, information storage, etc. In the energy field, micro devices such as microburners and microgenerators can be prepared. Microchannels can exist alone or form arrays, multi-stage pipelines, or mesh structures.

[0003] The preparation methods of microchannels mainly include micromachining, microelectronics manufacturing, photolithography, laser ablation, imprinting, rubbing and other technologies. Among them, micromachining is the most commonly used preparation method, including cutting, etching, impact forming, rotational forming, electrolytic processing, etc. Microchannels can be prepared using a variety of materials such as metals, silicon, glass, ceramics, polymers, etc.

[0004] The research and development team has applied for a Chinese invention patent, "A method for preparing a microchannel with adjustable tilt angle inside quartz glass" (publication number: CN 117161585 A); this solution uses nanosecond infrared laser to prepare a microchannel with adjustable tilt angle inside quartz glass; however, this solution requires the use of a high-power laser with an average laser power greater than 16W, and if a low-power laser is used, microchannel preparation cannot be achieved; when applied to large-scale production occasions, if a lower-power laser can be used, it can effectively reduce energy consumption and save production costs. Therefore, it is necessary to improve the microchannel preparation method. Summary of the invention

[0005] In order to overcome the shortcomings and deficiencies in the prior art, the purpose of the present invention is to provide a method for preparing a microchannel array inside a transparent material using a low-power laser; the method introduces a target material and uses a low-power laser to induce plasma-assisted ablation, so that an adjustable angle microchannel array can be prepared inside a transparent material; the microchannel array is simply and quickly formed, and is processed using a low-power laser, which can save energy consumption and reduce production costs.

[0006] In order to achieve the above object, the present invention is implemented by the following technical scheme: a method for preparing a microchannel array inside a transparent material using a low-power laser, comprising: Step S1, preheating the transparent material for preparing the microchannel array; placing a target material on a workbench, and placing the preheated transparent material closely above the target material; Step S2, adjusting the low-power laser to be incident perpendicular to the transparent material, and adjusting the laser focus to the interface between the transparent material and the target material; Step S3, setting the scanning speed of the low-power laser according to the tilt angle of the microchannel array and the distance between adjacent microchannels; and setting the scanning distance of each microchannel to be prepared according to the tilt angle of the microchannel array; obtaining the position information of the first microchannel to be prepared; Step S4, aiming a low-power laser at the position of the microchannel to be prepared on the lower surface of the transparent material; the plasma induced by the low-power laser from the target material ablates a microcavity on the lower surface of the transparent material, and the plasma is confined in the microcavity to increase the plasma density; A low-power laser is used for scanning, and during the scanning process, the laser focus is kept on the interface, so that the plasma induced from the target material and the plasma generated by the transparent material obtain a combined velocity consisting of a component velocity opposite to the laser propagation direction and a component velocity along the scanning direction, thereby obtaining a microchannel extending from the microcavity on the lower surface of the transparent material to the upper surface of the transparent material and having an adjustable inclination angle; Step S5, obtaining the position information of the next microchannel to be prepared; the projection of the next microchannel to be prepared and the prepared microchannel on the lower surface of the transparent material do not overlap; and step S4 is repeated until the preparation of the microchannel array is completed.

[0007] Preferably, the melting point of the target material is greater than the melting point of the transparent material; and the thermal conductivity of the target material is greater than the thermal conductivity of the transparent material.

[0008] Preferably, in step S1, a target is arranged on a workbench, and the preheated transparent material is arranged closely above the target, which means: the transparent material is pressed against the workbench, and the target is sandwiched between the transparent material and the workbench; the distance between the transparent material and the target is ≤10 μm.

[0009] Preferably, in step S1, preheating refers to preheating the transparent material to a set temperature; the set temperature is greater than or equal to 200° C. and less than the softening temperature of the transparent material.

[0010] Preferably, in step S3, the scanning speed of the low-power laser is set according to the inclination angle of the microchannel array and the spacing between adjacent microchannels, which means that the relationship between the inclination angle α of the microchannel, the spacing W between adjacent microchannels and the scanning speed x is as follows: α=0.002x 2 -1.04x+90.0875; W=0.94x 2+15.6x+188.125; The unit of scanning speed x is mm / s; the unit of tilt angle α is degree; and the unit of spacing W between adjacent microchannels is μm.

[0011] Preferably, the low-power laser scanning speed has a value range of 1 to 100 mm / s; The scanning setting distance refers to: the length of the microchannel to be formed projected on the lower surface of the transparent material.

[0012] Preferably, the low-power laser refers to a laser with an average power greater than or equal to 10W and less than 16W.

[0013] Preferably, the repetition frequency of the low-power laser is greater than 20 kHz.

[0014] Preferably, the target material is Ti6Al4V; and the transparent material is quartz glass.

[0015] Compared with the prior art, the present invention has the following advantages and beneficial effects: 1. The present invention introduces a target material and uses low-power laser-induced plasma-assisted ablation to prepare an angle-adjustable microchannel array inside a transparent material; the microchannel array is simple and fast to form, and low-power laser processing is used to save energy consumption and reduce production costs; 2. The present invention can change the inclination angle of the microchannel and the spacing of the microchannel by adjusting the scanning speed. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic flow chart of the method for preparing a microchannel array inside a transparent material using a low-power laser according to the present invention; Figure 2 It is a schematic diagram of the structure of a processing system used in the method of preparing a microchannel array inside a transparent material using a low-power laser of the present invention; Figure 3 This is an optical photograph of a molded sample of a microchannel array prepared by the method of the present invention; FIG4 (a) is a schematic diagram of the structure of a microchannel array prepared by the method of the present invention; FIG4( b ) is a line graph showing the changes in scanning speed, microchannel tilt angle, and spacing in the method of the present invention; Figure 5 The image of the microchannel prepared by the method of the present invention under a scanning electron microscope and its EDS spectrum test result; Figure 6 The present invention is a method for preparing a microchannel array inside a transparent material using a low-power laser DETAILED DESCRIPTION

[0017] The present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0018] Example This embodiment provides a method for preparing a microchannel array inside a transparent material using a low-power laser; the low-power laser used is a laser with an average power greater than or equal to 10 W and less than 16 W. The repetition frequency of the low-power laser is greater than 20 kHz.

[0019] Methods for preparing microchannel arrays inside transparent materials using low-power lasers, such as Figure 1 As shown, including: Step S1, preheating the transparent material for the microchannel array to be prepared. Preheating means preheating the transparent material to a set temperature; the set temperature is greater than or equal to 200°C and less than the softening temperature of the transparent material. A target material is set on a workbench, and the preheated transparent material is set closely above the target material. Specifically, the transparent material is pressed against the workbench, and the target material is sandwiched between the transparent material and the workbench; the distance between the transparent material and the target material is ≤10μm.

[0020] Requirements for target material selection: melting point of target material > melting point of transparent material; thermal conductivity of target material > thermal conductivity of transparent material.

[0021] Step S2, adjusting the low-power laser to be incident perpendicular to the transparent material, and adjusting the laser focus to the interface between the transparent material and the target material; Step S3, setting the scanning speed of the low-power laser according to the tilt angle of the microchannel array and the distance between adjacent microchannels; and setting the scanning distance of each microchannel to be prepared according to the tilt angle of the microchannel array; obtaining the position information of the first microchannel to be prepared; Step S4, aiming a low-power laser at the position of the microchannel to be prepared on the lower surface of the transparent material; the plasma induced by the low-power laser from the target material ablates a microcavity on the lower surface of the transparent material, and the plasma is confined in the microcavity to increase the plasma density; A low-power laser is used for scanning, and during the scanning process, the laser focus is kept on the interface, so that the plasma induced from the target material and the plasma generated by the transparent material obtain a combined velocity consisting of a component velocity opposite to the laser propagation direction and a component velocity along the scanning direction, thereby obtaining a microchannel extending from the microcavity on the lower surface of the transparent material to the upper surface of the transparent material and having an adjustable inclination angle; Step S5, obtaining the position information of the next microchannel to be prepared; the projection of the next microchannel to be prepared and the prepared microchannel on the lower surface of the transparent material do not overlap; and step S4 is repeated until the preparation of the microchannel array is completed.

[0022] The range of the low-power laser scanning speed is 1 to 100 mm / s. In step S3, the scanning speed of the low-power laser is set according to the inclination angle of the microchannel array and the spacing between adjacent microchannels, which means that the relationship between the inclination angle α of the microchannel, the spacing between adjacent microchannels W and the scanning speed x is as follows: α=0.002x 2 -1.04x+90.0875; W=0.94x 2 +15.6x+188.125; The unit of scanning speed x is mm / s; the unit of tilt angle α is degree; and the unit of spacing W between adjacent microchannels is μm.

[0023] The method for obtaining the scanning distance of the low-power laser is: according to the thickness and tilt angle of the transparent material, the positions of the two ends of the microchannel on the upper surface and the lower surface of the transparent material are obtained, and then the scanning distance is obtained.

[0024] The following is an example of a transparent material of quartz glass and a target material of Ti6Al4V. Quartz glass has a low melting point and low thermal conductivity; Ti6Al4V has a high melting point and high thermal conductivity, and is used as a target material. Figure 2 As shown, it includes a workbench 3, a power supply 4, a fiber laser 5, a lens group 6, a scanner 7, a focusing lens 8, and a computer 9. The target material 2 is arranged on the workbench 3, and the transparent material 1 is located on the target material 2.

[0025] A method for preparing a microchannel array inside a transparent material using a low-power laser comprises: Step S1, preheating the quartz glass at a temperature of 200°C to 1600°C; pressing the quartz glass onto a workbench, and sandwiching Ti6Al4V between the quartz glass and the workbench; keeping a minimum spacing between Ti6Al4V and the quartz glass as close to 0 as possible, taking 10 μm as an example.

[0026] Step S2, using an infrared nanosecond pulse low-power laser, the average laser power of the low-power laser is 12 W, the repetition frequency is 40 kHz, and the defocus is 0 mm; the low-power laser is adjusted to be incident perpendicular to the quartz glass, and the laser focus is set on the interface between the quartz glass and Ti6Al4V.

[0027] Step S3, obtaining the position information of the first microchannel to be prepared; Step S4, aiming a low-power laser at the position of the microchannel to be prepared on the lower surface of the quartz glass; and scanning with a low-power laser to prepare the microchannel.

[0028] Usually, it is difficult to process quartz glass with low-power lasers (such as nanosecond pulsed lasers). On the one hand, as a transparent material, quartz glass has an absorption rate of less than 5% from the visible light to the near-infrared spectrum; on the other hand, as a hard and brittle material, quartz glass is prone to cracks caused by thermal effects when processed with nanosecond lasers. However, through LIPAA (laser-induced plasma assisted ablation), as long as the distance between the target and the quartz glass is small enough, the quartz glass can be laser ablated like the target. This process involves the interaction between the target plasma, the incident laser and the lower surface of the quartz glass.

[0029] The working principle of the present invention is: first, due to the high light transmittance of quartz glass, most of the laser energy will be concentrated on the surface of the target material. When the laser energy flux density exceeds the ablation threshold of the target material, phenomena such as melting, evaporation and plasma jet will occur. The plasma jet expands, and the shock wave induced will exert a strong recoil pressure on the molten area of ​​the target material; at the same time, due to the extremely small distance between the quartz glass and the target material, the induced plasma will ablate the quartz glass substrate, and the induced shock wave will also generate a strong recoil pressure on the quartz glass substrate, causing pre-damage to the quartz glass substrate. If the kinetic energy of the ions in the plasma is higher than a certain critical energy value, the electrons in the quartz glass will be excited due to energy transfer, and the subsequent laser beam will be continuously absorbed by the excited electrons. After the quartz glass absorbs the laser, a huge temperature difference will be generated between the laser action area and the non-action area, resulting in the generation of thermally induced stress, which will lead to a decrease in the damage threshold. Therefore, under the combined action of molten droplet sputtering, plasma ablation, and shock waves, the quartz glass is more likely to be damaged, and the lower surface of the quartz glass is fully ablated.

[0030] After that, due to the existence of excited electrons, the quartz glass can continue to absorb subsequent laser energy. The laser energy is continuously absorbed in the damaged area of ​​laser ablation, and plasma is continuously generated. In the present invention, the distance between the quartz glass and the target material is extremely small, and the plasma will be confined to the microcavity ablated on the lower surface of the transparent material. It shields and absorbs the incident laser energy, and generates stronger shock waves and recoil pressure on the microcavity of the quartz glass. In this way, by utilizing the plasma continuously generated in the quartz glass and its ablation behavior, a microchannel that penetrates the glass in the opposite direction of the laser incident direction can be prepared.

[0031] As the low-power laser scans, the laser focus is maintained on the interface during the scanning process, so that the plasma induced from the target material and the plasma generated by the transparent material obtain a combined velocity consisting of a component velocity opposite to the laser propagation direction and a component velocity along the scanning direction, thereby obtaining a microchannel extending from the microcavity on the lower surface of the transparent material to the upper surface of the transparent material and with an adjustable inclination angle. When the plasma burns through the upper surface of the quartz glass and enters the air, the energy decreases sharply and dissipates rapidly due to the lack of the spatial confinement effect brought by the quartz glass medium. Repeat the above process to prepare the next microchannel to be prepared to ablate a microchannel array.

[0032] The present invention introduces a target material and uses laser-induced plasma-assisted ablation to prepare an angle-adjustable microchannel array inside a transparent material; the microchannel array is formed simply and quickly. The inclination angle of the microchannel and the spacing of the microchannel can also be changed by adjusting the scanning speed. In addition, under certain conditions, the process route can meet the requirements of completing all processes by one clamping, is suitable for large-scale processing, and reduces material and time costs.

[0033] Figure 3 This is a schematic diagram of preparing microchannels in quartz glass by LIPAA and optical photos of molded samples of microchannels prepared in quartz glass at six scanning speeds (2.5 mm / s, 5 mm / s, 7.5 mm / s, 10 mm / s, 12.5 mm / s, and 15 mm / s). After LIPAA line scanning, microchannels will be formed in the thickness direction of the quartz glass. The microchannels processed at the six scanning speeds have a tendency to tilt in the direction of the laser scanning speed, and the greater the scanning speed, the smaller the microchannel tilt angle α and the larger the microchannel spacing.

[0034] The structure of the microchannel array prepared by the method of the present invention is shown in FIG4(a); the line graph of the scanning speed, the tilt angle of the microchannel, and the spacing is shown in FIG4(b).

[0035] Figure 5 The images of the microchannel under a scanning electron microscope and its EDS spectrum test results are shown from the top, internal cross section, and bottom. The spectrum test shows that the main elements at the top outlet and inner wall of the microchannel are Si and O, and the main elements at the bottom inlet are Ti, Al, Si, and O, which proves that the plasma generated by Ti6Al4V only works in the initial ablation stage, and the subsequent ablation process depends on the plasma generated inside the quartz glass.

[0036] The method of the present invention for preparing a microchannel array inside a transparent material using a low-power laser, the microchannel array forming process is as follows Figure 6 shown.

[0037] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A method for preparing a microchannel array inside a transparent material using a low-power laser, characterized in that: include: Step S1, preheating the transparent material for preparing the microchannel array; placing a target material on a workbench, and placing the preheated transparent material closely above the target material; Step S2, adjusting the low-power laser to be incident perpendicular to the transparent material, and adjusting the laser focus to the interface between the transparent material and the target material; Step S3, setting the scanning speed of the low-power laser according to the tilt angle of the microchannel array and the distance between adjacent microchannels; and setting the scanning distance of each microchannel to be prepared according to the tilt angle of the microchannel array; Obtaining the position information of the first microchannel to be prepared; Step S4, aiming a low-power laser at the position of the microchannel to be prepared on the lower surface of the transparent material; the plasma induced by the low-power laser from the target material ablates a microcavity on the lower surface of the transparent material, and the plasma is confined in the microcavity to increase the plasma density; A low-power laser is used for scanning, and during the scanning process, the laser focus is kept on the interface, so that the plasma induced from the target material and the plasma generated by the transparent material obtain a combined velocity consisting of a component velocity opposite to the laser propagation direction and a component velocity along the scanning direction, thereby obtaining a microchannel extending from the microcavity on the lower surface of the transparent material to the upper surface of the transparent material and having an adjustable inclination angle; Step S5, obtaining the position information of the next microchannel to be prepared; Step S4 is repeated until the microchannel array is prepared.

2. The method for preparing a microchannel array inside a transparent material using a low-power laser according to claim 1, characterized in that: The melting point of the target material is greater than the melting point of the transparent material; the thermal conductivity of the target material is greater than the thermal conductivity of the transparent material.

3. The method for preparing a microchannel array inside a transparent material using a low-power laser according to claim 1, characterized in that: In the step S1, a target material is arranged on a workbench, and the preheated transparent material is arranged closely on the top of the target material, which means: the transparent material is pressed tightly on the workbench, and the target material is sandwiched between the transparent material and the workbench; the distance between the transparent material and the target material is ≤10 μm.

4. The method for preparing a microchannel array inside a transparent material using a low-power laser according to claim 1, characterized in that: In the step S1, preheating refers to preheating the transparent material to a set temperature; the set temperature is greater than or equal to 200° C. and less than the softening temperature of the transparent material.

5. The method for preparing a microchannel array inside a transparent material using a low-power laser according to claim 1, characterized in that: In step S3, the scanning speed of the low-power laser is set according to the inclination angle of the microchannel array and the spacing between adjacent microchannels, which means that the relationship between the inclination angle α of the microchannel, the spacing W between adjacent microchannels and the scanning speed x is as follows: α=0.002x 2 -1.04x+90.0875; W=0.94x 2 +15.6x+188.125; The unit of scanning speed x is mm / s; the unit of tilt angle α is degree; and the unit of spacing W between adjacent microchannels is μm.

6. The method for preparing a microchannel array inside a transparent material using a low-power laser according to claim 5, characterized in that: The low-power laser scanning speed has a value range of 1 to 100 mm / s.

7. The method for preparing a microchannel array inside a transparent material using a low-power laser according to claim 1, characterized in that: The low-power laser refers to a laser with an average power greater than or equal to 10W and less than 16W.

8. The method for preparing a microchannel array inside a transparent material using a low-power laser according to claim 1, characterized in that: The repetition frequency of the low-power laser is greater than 20 kHz.

9. The method for preparing a microchannel array inside a transparent material using a low-power laser according to claim 1, characterized in that: The target material is Ti6Al4V; the transparent material is quartz glass.

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