Method for fabricating microchannel arrays in transparent materials using low power laser

Abstract

The application provides a method for preparing a micro-channel array in a transparent material by using a low-power laser, comprising the following steps: preheating the transparent material; arranging a target material on a workbench and arranging the transparent material above the target material; adjusting the low-power laser to be perpendicular to the transparent material and adjusting a laser focus point of the low-power laser to be on an interface between the transparent material and the target material; setting a scanning speed and a scanning distance of the low-power laser according to an inclination angle of the micro-channel array and a distance between adjacent micro-channels; inducing a plasma from the target material by the low-power laser to ablate a micro-cavity on a lower surface of the transparent material, and limiting the plasma in the micro-cavity; and scanning the low-power laser, and keeping the laser focus point on the interface during the scanning process to obtain the micro-channel with the adjustable inclination angle. The method introduces the target material and uses the low-power laser to induce the plasma for ablation assistance, so that the micro-channel array with the adjustable inclination angle can be prepared in the transparent material, and energy consumption can be saved and production cost can be reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of microchannel preparation, and more particularly to a method for preparing a microchannel array in a transparent material by using a low-power laser. BACKGROUND

[0002] A microchannel is a channel structure with a size range of 10 microns to 1000 microns. Microchannels have a wide range of applications. For example, in the biomedical field, microfluidic chips can be prepared for detecting, separating, extracting, and analyzing biological samples such as DNA, RNA, and proteins. In the chemical field, flow catalysts can be prepared, and various compounds can be synthesized by using a microchannel reactor. In the mechanical manufacturing field, micro-mechanical components such as micro-pumps, micro-valves, micro-waves, and micro-heaters can be prepared. In the optical field, photonic crystals can be prepared for sensing and information storage. In the energy field, micro-burners and micro-generators can be prepared. Microchannels can exist alone or form an array, a multi-stage pipeline, or a network structure.

[0003] The main methods for preparing microchannels include micro-machining, micro-electronic manufacturing, photolithography, laser ablation, imprinting, and transfer printing. Among them, micro-machining is a commonly used method, which includes cutting, etching, impact forming, rotary forming, and electrolytic machining. Microchannels can be prepared from various materials such as metals, silicon, glass, ceramics, and polymers.

[0004] The present research team has applied for a Chinese invention patent entitled "Method for preparing a microchannel with adjustable inclination angle in quartz glass" (Publication No. CN 117161585 A). This method uses a nanosecond infrared laser to prepare a microchannel with adjustable inclination angle in quartz glass. However, this method requires a high-power laser with an average power greater than 16W. If a low-power laser is used, the microchannel cannot be prepared. In large-scale production, if a lower power laser is used, energy consumption can be reduced and production costs can be saved. Therefore, the microchannel preparation method needs to be improved. SUMMARY

[0005] To overcome the shortcomings and deficiencies in the prior art, the present application aims to provide a method for preparing a microchannel array in a transparent material by using a low-power laser. This method introduces a target material and uses a low-power laser-induced plasma-assisted ablation to prepare a microchannel array with adjustable angles in a transparent material. The microchannel array is simple and fast to form, and the use of a low-power laser can save energy and reduce production costs.

[0006] To achieve the above-mentioned purpose, the present application realizes it by the following technical scheme: a method for preparing a microchannel array in a transparent material by using a low-power laser, comprising:

[0007] Step S1, preheat the transparent material to be prepared into a microchannel array; a target material is arranged on the workbench, and the preheated transparent material is arranged closely above the target material;

[0008] Step S2, adjust the low-power laser to be perpendicular to the transparent material, and adjust the laser focal point on the interface between the transparent material and the target material;

[0009] Step S3, set the scanning speed of the low-power laser according to the inclination angle and the adjacent microchannel spacing of the microchannel array; and set the scanning distance of each microchannel to be prepared according to the inclination angle of the microchannel array; and obtain the position information of the first microchannel to be prepared;

[0010] Step S4, the low-power laser is aligned with the position of the current microchannel to be prepared on the lower surface of the transparent material; the plasma induced from the target material ablates a microcavity on the lower surface of the transparent material, and the plasma is confined in the microcavity to improve the plasma density;

[0011] The low-power laser performs scanning, and the laser focal point is kept 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 resultant velocity composed of a velocity opposite to the laser propagation direction and a 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;

[0012] Step S5, obtain the position information of the next microchannel to be prepared; the next microchannel to be prepared does not overlap with the prepared microchannel on the projection of the lower surface of the transparent material; repeat step S4 until the microchannel array is prepared.

[0013] Preferably, the melting point of the target material > the melting point of the transparent material; the thermal conductivity of the target material > the thermal conductivity of the transparent material.

[0014] Preferably, in step S1, the target material is arranged on the workbench, and the preheated transparent material is arranged closely above the target material, which means that the transparent material is pressed on the workbench, and the target material is clamped between the transparent material and the workbench; the distance between the transparent material and the target material is ≤10μm.

[0015] Preferably, in step S1, the preheating means preheating the transparent material to a set temperature; the set temperature is greater than or equal to 200℃ and less than the softening temperature of the transparent material.

[0016] Preferably, in step S3, the scanning speed of the low-power laser is set according to the inclination angle and the adjacent microchannel spacing of the microchannel array, which means that the inclination angle α and the adjacent microchannel spacing W of the microchannel are respectively related to the scanning speed x as follows:

[0017] a = 0.002x 2 -1.04x + 90.0875;

[0018] W = 0.94x 2 + 15.6x + 188.125;

[0019] Wherein, the unit of scanning speed x is mm / s; the unit of tilt angle a is degree; the unit of adjacent microchannel spacing W is μm.

[0020] Preferably, the scanning speed of the low-power laser ranges from 1 to 100 mm / s.

[0021] The scanning setting distance refers to the length of the microchannel formed on the lower surface of the transparent material.

[0022] Preferably, the low-power laser refers to a laser with an average power greater than or equal to 10 W and less than 16 W.

[0023] Preferably, the repetition frequency of the low-power laser is greater than 20 kHz.

[0024] Preferably, the target material refers to Ti6Al4V; and the transparent material refers to quartz glass.

[0025] Compared with the prior art, the present application has the following advantages and beneficial effects:

[0026] 1. The present application 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 simple and fast to form, and the use of a low-power laser can save energy and reduce production cost.

[0027] 2. The present application can change the tilt angle of the microchannel and the spacing of the microchannel by adjusting the scanning speed. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 is a flowchart of the method for preparing a microchannel array inside a transparent material by a low-power laser of the present application;

[0029] Figure 2 is a structural diagram of the processing system used in the method for preparing a microchannel array inside a transparent material by a low-power laser of the present application;

[0030] Figure 3 is an optical photo of the formed sample of the microchannel array prepared by the method of the present application;

[0031] Figure 4 (a) is a structural diagram of the microchannel array prepared by the method of the present application;

[0032] Figure 4(b) is a graph of the scanning speed of the method of the present application versus the change in the tilt angle and spacing of the microchannels;

[0033] Figure 5 is the image of the microchannels prepared by the method of the present application under a scanning electron microscope and the EDS energy spectrum test results thereof;

[0034] Figure 6 is a method of preparing a microchannel array in a transparent material by a low-power laser DETAILED DESCRIPTION

[0035] The present application will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0036] EMBODIMENT

[0037] The present embodiment is a method of preparing a microchannel array in a transparent material by a low-power laser. The low-power laser used refers to 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.

[0038] The method of preparing a microchannel array in a transparent material by a low-power laser, as shown in Figure 1 , comprises the following steps:

[0039] Step S1, preheat the transparent material to be prepared for the microchannel array. 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. A target material is provided on the workbench, and the preheated transparent material is tightly arranged above the target material. Specifically, the transparent material is tightly pressed on the workbench, and the target material is clamped between the transparent material and the workbench; the spacing between the transparent material and the target material is ≤10 μm.

[0040] Selection requirements for the target material: melting point of the target material > melting point of the transparent material; thermal conductivity of the target material > thermal conductivity of the transparent material.

[0041] Step S2, adjust the low-power laser to be perpendicular to the transparent material, and adjust the laser focal point to be on the interface between the transparent material and the target material;

[0042] Step S3, set the scanning speed of the low-power laser according to the tilt angle and the spacing between adjacent microchannels of the microchannel array; set the scanning distance of each microchannel to be prepared according to the tilt angle of the microchannel array; and obtain the position information of the first microchannel to be prepared;

[0043] Step S4, align the position of the current microchannel to be prepared on the lower surface of the transparent material by the low-power laser; the plasma induced 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;

[0044] The low-power laser is scanned, and the laser focus is kept 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 resultant velocity composed of a velocity opposite to the laser propagation direction and a velocity along the scanning direction, thereby obtaining a microchannel extending from the lower surface of the transparent material to the upper surface of the transparent material and having an adjustable inclination angle.

[0045] In step S5, position information of a next microchannel to be prepared is obtained; the next microchannel to be prepared does not overlap with the prepared microchannel in the projection on the lower surface of the transparent material; and step S4 is repeatedly executed until the microchannel array is prepared.

[0046] The scanning speed of the low-power laser ranges from 1 mm / s 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 distance between adjacent microchannels, that is, the relationship between the inclination angle α of the microchannel, the distance W between adjacent microchannels and the scanning speed x is as follows:

[0047] α = 0.002x 2 -1.04x + 90.0875;

[0048] W = 0.94x 2 + 15.6x + 188.125;

[0049] The unit of the scanning speed x is mm / s; the unit of the inclination angle α is degree; and the unit of the distance W between adjacent microchannels is μm.

[0050] The scanning distance of the low-power laser is obtained according to the thickness of the transparent material and the inclination angle, the positions of the two ends of the microchannel on the upper surface and the lower surface of the transparent material, and the scanning distance.

[0051] The transparent material is quartz glass, and the target material is Ti6Al4V, for example. The melting point of quartz glass is relatively low, and the thermal conductivity is relatively low; the melting point of Ti6Al4V is relatively high, and the thermal conductivity is relatively high, so it is used as the target material. A processing system is used, as shown in FIG. 1, which 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 arranged on the target material 2. Figure 2 The method for preparing a microchannel array in a transparent material by using a low-power laser includes the following steps.

[0052]

[0053] ​Step S1, preheat the quartz glass, the preheating temperature is 200-1600 DEG C; the quartz glass is pressed on the workbench, and Ti6Al4V is arranged between the quartz glass and the workbench; Ti6Al4V and quartz glass are kept as close to 0 as possible, and 10 microns are taken as an example.

[0054] Step S2, a small power laser is used, the average laser power of the small power laser is 12 W, the repetition frequency is 40 kHz, and the defocusing amount is 0 mm; the small power laser is adjusted to be perpendicular to the quartz glass, and the laser focus is set on the interface between the quartz glass and Ti6Al4V.

[0055] Step S3, the position information of the first to be prepared microchannel is obtained.

[0056] Step S4, the small power laser is aligned with the position of the current to be prepared microchannel on the lower surface of the quartz glass; the small power laser scans to prepare the microchannel.

[0057] Generally, it is difficult for a small power laser (such as a nanosecond pulse laser) to process quartz glass. On the one hand, as a transparent material, the absorption rate of quartz glass to visible light to near-infrared spectrum is less than 5%; on the other hand, as a hard and brittle material, the quartz glass is easy to cause cracks caused by thermal effects when using a nanosecond laser for processing. But through LIPAA (laser-induced plasma-assisted ablation), as long as the distance between the target material and the quartz glass is small enough, the quartz glass can be ablated by the laser as the target material. This process includes the interaction between the target plasma, the incident laser and the lower surface of the quartz glass.

[0058] The working principle of the application is: first, due to the high light transmittance of the quartz glass, most of the laser energy will converge on the surface of the target material. When the laser energy flux density exceeds the ablation threshold of the target material, melting, evaporation and plasma jet will occur. The plasma jet expands, and the shock wave induced will exert strong recoil pressure on the molten region 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 shock wave induced will also produce 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 continue to be absorbed by the excited state electrons. After the quartz glass absorbs the laser, a large temperature difference will be generated between the laser action area and the non-action area, resulting in the generation of thermal stress, which will lead to the reduction of the damage threshold. Therefore, under the combined action of molten droplet sputtering, plasma ablation and shock wave, the quartz glass is more prone to damage, and the lower surface of the quartz glass is fully ablated.

[0059] After that, the quartz glass can continuously absorb the subsequent laser energy due to the existence of the excited state electron. The laser-ablated damage area continuously absorbs the laser energy, and the plasma continuously generates. In the present application, the distance between the quartz glass and the target material is very small, and the plasma will be confined in the microcavity ablated on the lower surface of the transparent material, which shields and absorbs the incident laser energy, and generates stronger shock wave and recoil pressure on the microcavity of the quartz glass. In this way, by using the continuously generated plasma in the quartz glass and its ablation behavior, the microchannels penetrating the glass in the direction opposite to the laser incidence direction can be prepared.

[0060] With the scanning of the low-power laser, the laser focus is kept 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 the combined velocity composed of the velocity opposite to the laser propagation direction and the velocity along the scanning direction, thereby obtaining the microchannels extending from the microcavity on the lower surface of the transparent material to the upper surface of the transparent material and having adjustable inclination angle. When the plasma burns through the upper surface of the quartz glass into the air, the energy sharply decreases and rapidly dissipates due to the absence of the spatial confinement effect of the quartz glass medium. The above process is repeated to prepare the next microchannel to be prepared, so as to ablate the microchannel array.

[0061] The present application introduces the target material and uses the laser-induced plasma assisted ablation to prepare the microchannel array with adjustable angle in the transparent material; the microchannel array is simply and rapidly formed. The inclination angle of the microchannel and the interval of the microchannel can be changed by adjusting the scanning speed. In addition, under certain conditions, the process route can meet the requirement of completing all processes by one clamping, is suitable for large-scale processing, and reduces the cost of material and time.

[0062] Figure 3 The microchannel prepared in the quartz glass by LIPAA is shown in the schematic diagram, and the optical photos of the formed samples of the microchannel prepared in the quartz glass at six scanning speeds (2.5 mm / s, 5 mm / s, 7.5 mm / s, 10 mm / s, 12.5 mm / s, 15 mm / s) are shown. After the LIPAA line scanning, a plurality of microchannels are formed in the thickness direction of the quartz glass. The microchannels processed at the six scanning speeds all have the inclination trend towards the direction of the laser scanning speed, and the greater the scanning speed is, the smaller the inclination angle α of the microchannel is, and the greater the interval of the microchannels is.

[0063] The structure of the microchannel array prepared by the method of the present application is shown in Fig. 4 (a); and the change fold line graph of the scanning speed, the inclination angle and the interval of the microchannel is shown in Fig. 4 (b).

[0064] Figure 5The images of the microchannels and their EDS energy spectrum test results under scanning electron microscope are shown from top, inner section and bottom in sequence. The energy spectrum detection shows that the main elements of the top outlet and inner wall of the microchannels are Si and O, and the main elements of the bottom inlet are Ti, Al, Si and O, which proves that the plasma generated by Ti6Al4V only plays a role in the initial ablation stage, and the subsequent ablation process relies on the plasma generated inside the quartz glass.

[0065] The method for preparing the microchannel array in the transparent material by the low-power laser of the application is shown in the following microchannel array forming process. Figure 6

[0066] The above-mentioned embodiments are the preferred embodiments of the application, but the embodiments of the application are not limited to the above-mentioned embodiments, and any changes, modifications, substitutions, combinations, simplifications made without departing from the spirit and principles of the application shall be equivalent replacement modes, which are all included in the protection scope of the application.​

Claims

1. A method of fabricating an array of microchannels in a transparent material by low power laser, characterized in that: The application relates to a method for preparing a micro-channel array on a transparent material. The method comprises the following steps: S1, preheating the transparent material to be prepared into a micro-channel array; a target material is arranged on a workbench, and the preheated transparent material is arranged above the target material in close contact; S2, adjusting a low-power laser to be perpendicular to the transparent material, and adjusting a laser focus point on the interface between the transparent material and the target material; S3, setting a scanning speed of the low-power laser according to the inclination angle of the micro-channel array and the interval between adjacent micro-channels, and setting a scanning distance of each micro-channel to be prepared according to the inclination angle of the micro-channel array; acquiring position information of a first micro-channel to be prepared; S4, aligning the low-power laser to the position of the micro-channel to be prepared on the lower surface of the transparent material; plasma induced from the target material ablates a micro-cavity on the lower surface of the transparent material, and the plasma is limited in the micro-cavity to improve the plasma density; the low-power laser performs scanning, and the laser focus point is kept on the interface during the scanning process, so that the plasma induced from the target material and the plasma generated from the transparent material obtain a resultant velocity composed of a velocity opposite to the laser propagation direction and a velocity along the scanning direction, thereby obtaining a micro-channel extending from the micro-cavity on the lower surface of the transparent material to the upper surface of the transparent material and adjustable in inclination angle; S5, acquiring position information of a next micro-channel to be prepared; repeating the step S4 until the micro-channel array is prepared; a = 0.002x 2 -1.04x + 90.0875; W = 0.94x 2 + 15.6x + 188.125; in the step S3, the scanning speed of the low-power laser is set according to the inclination angle of the micro-channel array and the interval between adjacent micro-channels, that is, the relationship between the inclination angle alpha of the micro-channel, the interval W between adjacent micro-channels and the scanning speed x is as follows: wherein the unit of the scanning speed x is mm / s, the unit of the inclination angle alpha is degree, and the unit of the interval W between adjacent micro-channels is mu m; 2. The method of claim 1, wherein: the low-power laser refers to a laser with an average power greater than or equal to 10 W and less than 16 W.

3. The method of claim 1, wherein: the melting point of the target material is greater than that of the transparent material, and the thermal conductivity of the target material is greater than that of the transparent material.

4. The method of claim 1, wherein: in the step S1, the target material is arranged on the workbench, and the preheated transparent material is arranged above the target material in close contact, that is, the transparent material is pressed on the workbench, and the target material is clamped between the transparent material and the workbench; the interval between the transparent material and the target material is less than or equal to 10 mu m.

5. The method of claim 1, wherein: in the step S1, the preheating refers to preheating the transparent material to a set temperature; the set temperature is greater than or equal to 200 DEG C and less than the softening temperature of the transparent material.

6. The method of claim 1, wherein: the scanning speed of the low-power laser ranges from 1 mm / s to 100 mm / s.

7. The method of claim 1, wherein: the repetition frequency of the low-power laser is greater than 20 kHz. the target material refers to Ti6Al4V, and the transparent material refers to quartz glass.

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