CN106890684B - Glass-based chip and manufacturing method thereof - Google Patents

Abstract

The invention relates to a glass-based microfluidic chip and a manufacturing method thereof. There is a microchannel inside the glass-based chip, and the microchannel includes several first microchannels, and the first microchannel is a closed chamber; the manufacturing method includes the following steps: obtaining a bottom glass sheet and a cover glass sheet; The microchannel is formed after bonding the cover glass sheet to the bottom glass sheet to obtain a bonded sheet; transferring the bonded sheet to a heating device, and raising the temperature at a rate of 0.5-2°C/min to above the annealing temperature of the glass; and then undergo an annealing and cooling process to obtain the glass-based chip. The present invention aims at the glass sheet containing the closed microstructure, by reasonably adjusting the heating rate, the trace moisture in the first microchannel can be evenly vaporized and evaporated in the process of heating up and bonding, so as to ensure the structure of the closed microchannel and save The production time of the chip is reduced, and the production efficiency is improved.

Description

Glass-based chip and manufacturing method thereof

technical field

The invention relates to a microfluidic chip manufacturing technology, in particular to a glass-based chip and a manufacturing method thereof.

Background technique

Microfluidic chip is a science and technology characterized by the manipulation of fluids in micron-sized channels. The ability on the centimeter chip, so it is also called "micro-total analysis system". Due to the characteristics of high integration, low reagent consumption, fast analysis speed, and easy automation, microfluidic chips have been extensively studied by researchers, and commercial products have appeared in the fields of biology, medicine, and chemistry.

The materials used to make microfluidic chips include glass, polymer materials, paper, etc. Among them, many universities and research institutes have related experimental equipment to make polydimethylsiloxane (PDMS)-based microfluidic chips. Chip - A polymer material chip. However, the poor electroosmotic performance of PDMS-based microfluidic chips makes it difficult to apply to electrophoresis experiments; PDMS is a hydrophobic material, and when using water-soluble samples for experiments, it is often necessary to treat the chip with hydrophilicity. Therefore, PDMS-based microfluidic chips are limited in use to a certain extent.

Like PDMS, glass is also a material commonly used in processing microfluidic chips, which has the characteristics of high Young's modulus, stable chemical and thermal properties, low electrical conductivity, and good transparency.

At present, there are many methods for bonding glass-based microfluidic chips. Although some researchers have tried relatively simple reversible bonding methods such as epoxy resin adhesive method and film bonding method, but the results are not satisfactory, so the irreversible high-temperature bonding method has a wider range of applications. The high-temperature bonding method refers to bonding two clean glass sheets to be bonded together, and then transferring them to a muffle furnace, and raising the temperature above the annealing temperature of the glass by heating and pressing. The bonding process of the entire chip is completed through temperature control stages such as annealing and cooling. However, when the chip contains a closed microstructure, such as the scale marks representing the distance etched on the side of the separation channel of the cross-shaped chip, it is difficult to form a closed microchannel structure according to the conventional high-temperature bonding method, and it may even destroy the structure of the chip. The overall structure makes it difficult to guarantee the product quality of glass-based microfluidic chips.

In addition, the currently commonly used method for fabricating glass-based microfluidic chips is the method of standard photolithography combined with wet etching: the mask containing the pattern structure is covered on the glass pre-coated with a thin photoresist layer and a sacrificial layer (even Then, under the irradiation of a certain intensity of parallel ultraviolet light, the pattern on the mask is transferred to the uniform chromium plate; and then through the steps of developing, fixing and wet etching, it can be manufactured on the uniform chromium plate Produce the desired microstructure; the colloidal chromium plate containing the microstructure is then bonded and packaged with a cover glass to produce a complete chip. However, adopting this method needs to make a homogeneous chrome plate, which involves purchasing expensive instruments and equipment. This not only makes the cost of processing glass-based microfluidic chips rise sharply, but also makes it difficult for some small companies and beginner researchers to have corresponding economic capabilities. Although some people currently use laser ablation, powder bombardment, ultrasonic and other technologies to process microchannels on glass, the roughness of microchannels obtained by these mechanical processing methods is relatively large, which is difficult to meet the requirements of use.

Contents of the invention

Based on this, it is necessary to provide a method for manufacturing a glass-based chip.

A method for manufacturing a glass-based chip, the glass-based chip has microchannels inside, the microchannels include a plurality of first microchannels, and the first microchannels are closed chambers;

Described preparation method comprises the steps:

Obtain the bottom and cover glass slides;

After bonding the cover glass sheet to the bottom glass sheet, the microchannel is formed to obtain a bonding sheet;

Transfer the bonded sheet to a heating device, and raise the temperature above the annealing temperature of the glass at a heating rate of 0.5-2° C./min; then undergo an annealing and cooling process to obtain the glass-based chip.

The present invention finds through research that for a glass-based chip containing a closed microchannel (i.e. the first microchannel), when the traditional high-temperature bonding method is used, the trace moisture contained therein will vaporize rapidly, causing it to form during fusion bonding. The air cavity, thereby affecting or even destroying the structure of the first microchannel. However, if a step-by-step high-temperature bonding method is adopted, that is, the chip to be bonded is dried in a drying oven at a low temperature (usually 60-100°C) until the water in the sub-microchannel disappears and then transferred to the muffle furnace. Even more than ten hours, this will undoubtedly increase the production time and steps of the chip.

Based on this, the manufacturing method of the glass-based chip of the present invention can uniformly vaporize and evaporate the trace moisture in the first microchannel during the heating and bonding process by reasonably controlling the heating rate at 0.5-2°C/min. Ensuring the structure of the closed microchannel can save the manufacturing time of the chip and improve the production efficiency.

The annealing temperature of the glass described in the present invention can be routinely determined according to different glass materials.

In one embodiment, the heating rate is 0.8-1.5° C./min.

In one of the embodiments, the temperature is raised to 545-555°C at a heating rate (average rate) of 0.9-1.1°C/min, and kept at 545-555°C for 55-65min; 605°C, and keep warm at 595~605°C for 175~185min.

In one embodiment, the annealing and cooling step is to lower the temperature to room temperature at an average rate of 1-3° C./min.

In one of the embodiments, the microchannel further includes several second microchannels; the second microchannel has several openings communicating with the atmosphere.

In one of the embodiments, a depression is etched on the surface of the bottom glass, and after the cover glass is bonded to the surface, the microscopic area is formed between the depression and the cover glass. aisle.

In one of the embodiments, a depression is etched on the surface of the bottom glass, and after the cover glass is bonded to the surface, the microscopic area is formed between the depression and the cover glass. aisle;

The method for obtaining the bottom glass sheet comprises the steps:

Obtaining a substrate, the substrate is etched with a substrate depression, and is provided with a liquid inlet connected to the substrate depression; the substrate depression and the depression etched on the surface of the bottom glass sheet Corresponding to the department;

performing reversible bonding on the substrate and the glass sheet, forming a cavity between the recessed part of the substrate and the surface of the glass sheet;

Injecting an etching solution into the chamber from the liquid inlet to etch the glass sheet, that is, forming the depression on the surface of the glass sheet;

The substrate is removed to obtain the bottom glass sheet.

The method for making the bottom glass sheet is to carry out reversible bonding between the substrate and the glass sheet that have been etched with the recessed portion of the substrate, and then inject an etching solution into the formed chamber. The shape of the glass sheet can be etched to form the depression on the surface of the glass sheet accordingly, so that it is not necessary to make and use a uniform chromium plate, avoiding expensive equipment purchase costs, and avoiding the use of a uniform chromium plate. The problem of heavy metal pollution of the environment, and simple operation, low processing difficulty and cost, easy to mass production, can carry out chip processing in most scientific research institutes and enterprises, has a good application prospect.

In one embodiment, the etching solution includes hydrofluoric acid (HF), nitric acid and water in a volume ratio of 1:1˜3:15˜25.

For the production of the bottom glass sheet, if the glass is made of a material containing more metal oxides, it is easy to react with hydrofluoric acid to form a precipitate that is difficult to tolerate in water, which in turn affects the etching quality of the microchannel. The present invention rationally controls the volume ratio of hydrofluoric acid, nitric acid and water by adopting the above etching solution, while ensuring that the etching solution has a fast enough etching rate for glass, it not only avoids the problem caused by excessive concentrations of hydrofluoric acid and nitric acid High damage to the bonding of the substrate and the glass sheet also ensures the accuracy and uniformity of the microchannel formation on the bottom glass sheet.

The above etching time depends on the required depth of the recessed portion. In one embodiment, the etching time is 40 min, and the temperature is 25°C.

In one embodiment, the material of the substrate is one or more combinations of polydimethylsiloxane (PDMS), polymethylmethacrylate (PMMA), and polycarbonate (PC). The substrate using the material does not react with the etching solution during the etching process, and can avoid affecting the reaction between the etching solution and the glass sheet.

In one embodiment, after reversibly bonding the substrate and the glass sheet, the resulting chip is heated and baked at a temperature of 60-70° C. for 1-3 hours. To increase the adhesion between the substrate and the glass sheet.

In one embodiment, the reversible bonding method is one or a combination of pressure bonding, adhesive bonding, and oxygen plasma method.

In one embodiment, the injection rate of the etching solution is 0.1 μL/min˜5 μL/min. When the reversible bonding method is an oxygen plasma method, the injection rate of the etching solution is preferably 0.5 μL/min˜2 μL/min.

In one embodiment, the method for removing the substrate is: soaking in concentrated sulfuric acid or a mixture of concentrated sulfuric acid and other strong acids and then removing.

In one embodiment, after the substrate is removed, the bottom glass is rinsed with water, and the liquid in the recess is blown out with nitrogen.

The present invention also provides the glass-based chip manufactured by the method for manufacturing the glass-based chip.

Compared with the prior art, the present invention has the following beneficial effects:

In the method for manufacturing a glass-based chip of the present invention, for the glass-based chip containing the first microchannel, by reasonably adjusting the heating rate to 0.5-2°C/min, the temperature in the first microchannel can be increased during the bonding process. A small amount of water is evenly vaporized and evaporated to ensure a closed microchannel structure, which can save chip manufacturing time and improve production efficiency.

In the method for making the bottom glass sheet of the present invention, firstly, the substrate with the recessed portion of the substrate etched is reversibly bonded to the glass sheet, and then etched with an etching solution, so that the glass sheet can be formed on the surface of the glass sheet. the recessed part. Therefore, there is no need to make and use the chrome plate, which avoids expensive equipment purchase costs, and avoids the problem of environmental pollution caused by heavy metals caused by the use of the chrome plate. The operation is simple, the processing difficulty and cost are low, and it is convenient for batches Production, chip processing can be carried out in most scientific research institutes and enterprises, and has a good application prospect.

Description of drawings

Fig. 1 is the structural representation of the bottom glass sheet in an embodiment of the present invention;

Fig. 2 is a schematic diagram of the production process of the bottom glass sheet in an embodiment of the present invention;

Fig. 3 is a schematic diagram of the manufacturing process of the substrate in an embodiment of the present invention;

Fig. 4 is a physical diagram of a glass-based microfluidic chip fabricated in an embodiment of the present invention.

Detailed ways

The glass-based chip and its manufacturing method of the present invention will be further described in detail below in conjunction with specific examples.

Example

This embodiment provides a method for manufacturing a glass-based microfluidic chip. The glass-based microfluidic chip has a microchannel inside, and the microchannel includes a first microchannel, and the first microchannel does not communicate with the atmosphere. The openings are closed microstructures. In this embodiment, the glass-based microfluidic chip is further provided with an opening, and the microchannel further includes a second microchannel, the two ends of the second microchannel are connected to the opening, forming two possible An opening that communicates with the atmosphere. It can be understood that, in other embodiments, both ends of the second microchannel may also be connected to the edge of the glass-based microfluidic chip to form an opening communicating with the atmosphere.

Above-mentioned preparation method comprises the steps:

(1) Obtain bottom glass sheet and cover glass sheet;

(2) Clean the bottom glass sheet and the cover glass sheet, and bond them together in ultrapure water to form the above-mentioned microchannels to obtain a bonded sheet;

(3) Transfer the bonded sheet to a muffle furnace, raise the temperature above the annealing temperature of the glass at a heating rate of 0.5-2° C./min, and then undergo an annealing and cooling process to obtain a glass-based microfluidic chip.

In this embodiment, the material of the bottom glass sheet and the cover glass sheet is soda lime glass; the annealing temperature is 500-530°C.

In this example, the temperature raising method is specifically to raise the temperature to 550°C at an average rate of 1°C/min, and keep it at 550°C for 60 minutes; then raise the temperature to 600°C within 60 minutes, and keep it at 600°C for 180 minutes. Then anneal at an average rate of 2°C/min and cool down to room temperature.

Therefore, in the process of heating up and bonding, the microchannel, especially the trace moisture in the first microchannel can be vaporized and evaporated to the greatest extent, ensuring the structure of the closed microchannel, which can save the production time of the chip and improve the production efficiency. efficiency.

In this embodiment, as shown in FIG. 1 , a recessed portion is etched on the surface of the bottom glass sheet 10 , the recessed portion includes a first recessed portion 11 and a second recessed portion 12 , and an opening 13 is also provided. Wherein, both ends of the first depressed portion 11 are located within the edge of the bottom glass sheet 10, and after the bottom glass sheet and the cover glass sheet are bonded together, the first concave portion 11 and the cover glass sheet are formed between the first depressed portion 11 and the cover glass sheet. Micro channel; both ends of the second recessed part 12 are connected to the opening 13, after the bottom glass sheet and the cover glass sheet are bonded together, the second micro channel is formed between the second recessed part 12 and the cover glass sheet.

As shown in Figure 2, the method for obtaining the bottom glass sheet 10 comprises the following steps:

1.1 Obtain the substrate, as shown in Figure 2a, the substrate 20 is provided with a substrate recessed portion 21, the pattern of the substrate recessed portion 21 is made according to the recessed portion that needs to be etched on the surface of the bottom glass sheet 10, and this recessed portion Corresponding. Specifically, the substrate recess 21 includes a first substrate recess and a second substrate recess, the first substrate recess corresponds to the first recess 11, and the substrate 20 is also provided with a The liquid inlet 22 of the depression of the first substrate can be formed by punching at a suitable position with a puncher, and the number can also be set according to needs, so as to ensure that all the depressions of the first substrate can be carried out later. The perfusion of etching solution is sufficient. The second substrate recess corresponds to the second recess 12 .

In this embodiment, the material of the substrate is PDMS. It can be understood that in other embodiments, PMMA and/or PC can also be used, thus ensuring that the substrate does not react with the etching solution during the etching process, and can avoid affecting the reaction between the etching solution and the glass sheet .

The glass sheet 30 is taken, and the glass sheet 30 is drilled with a laser, an ultrasonic wave or a diamond drill to form an opening 13 (not shown in FIG. 2 ).

1.2 As shown in Figure 2b, the substrate 20 and the glass sheet 30 (Jiangsu Shitai Experimental Equipment Co., Ltd., standard microscope slide) are reversibly bonded, and the concave part of the first substrate and the surface of the glass sheet 30 form a second One chamber, the second substrate recessed part and the surface of the glass sheet 30 form the second chamber, and a PDMS-glass hybrid microfluidic chip is obtained.

In this embodiment, the reversible bonding method is an oxygen plasma method, and after bonding, the obtained chip is heated and baked at a temperature of 65° C. for 2 hours to increase the bond between the substrate 20 and the glass sheet. Bond between 30. It can be understood that in other embodiments, heating and baking are not performed, or other reversible bonding methods are used, such as one or a combination of adhesive bonding and pressure bonding.

1.3 Filling the first chamber and the second chamber with etching solution:

As shown in Figure 2c, for the first chamber, one end of the plastic tube is connected to the liquid inlet 22 of the substrate 20, and the other end is connected to the syringe 40 pre-filled with etching solution, and then the syringe 40 is fixed on the Injection pump 50 on. By setting the flow rate of the sampling pump 50, the sampling pump 50 continuously or intermittently pours the etching solution into the first chamber after starting, thereby etching the glass sheet 30, that is, forming the etching solution on the surface of the glass sheet. Describe the first recessed portion.

For the second chamber, since the first substrate recess communicates with the opening 13 and forms an opening, no additional opening is required, and one end of the plastic tube is connected to the opening, and the other end is connected to the syringe 40 . Then, similarly, by setting the flow rate of the sampling pump 50, the sampling pump 50 will continuously or intermittently pour the etching solution into the second chamber after starting, thereby etching the glass sheet 30, that is, the glass sheet 30 will be etched. The surface of the sheet forms the second depression.

In this embodiment, the etching solution used includes HF, nitric acid and water at a volume ratio of 1:2:21, and the injection rate of the etching solution is 0.5 μL/min˜2 μL/min. The time required for perfusing the etching solution depends on the etching rate of the etching solution and the required channel depth of the glass-based microfluidic chip. In this embodiment, the etching time is 40 minutes and the temperature is 25° C.

1.4 Remove the substrate, and then place the obtained glass sheet in concentrated sulfuric acid to further remove the residual PDMS. After taking it out, rinse the obtained glass sheet with water, and blow out the liquid in the depression with nitrogen gas to prevent the residual etching solution from affecting the glass sheet. Continue the etching to obtain a glass sheet having a depression corresponding to the pattern of the substrate depression 21, that is, the bottom glass sheet 10, as shown in FIG. 2d.

More specifically, in this embodiment, as shown in Figure 3, the method for obtaining the substrate in step 1.1 may include the following steps:

1.1.1 Silicon wafer cleaning: The surface of the silicon wafer is cleaned through conventional degreasing, pickling, and water washing steps. Specifically, it can be washed with acetone, concentrated sulfuric acid, and ultrapure water in sequence; then it is dehumidified and dried, as shown in Figure 3a.

1.1.2 Coating: Place the clean silicon wafer on a coating machine, and coat it with a certain thickness of negative photoresist (SU-8 photoresist) by spin coating method, as shown in Figure 3b.

1.1.3 Pre-baking: bake the silicon wafer coated with negative photoresist by means of a hot plate or a constant temperature heating box to volatilize the solvent in the negative photoresist solution. The baking condition is to bake at 95 ° C for 15 minutes .

1.1.4 Exposure: Place the mask between the negative photoresist and the light source of the photolithography machine, and use ultraviolet light for exposure. The exposure time can be 10s, so that the channel pattern on the mask is transferred to the negative photoresist. Figure 3c.

1.1.5 Post-baking: After the exposure is over, place the exposed silicon wafers on a hot plate or a constant temperature heating box for post-baking. The post-baking conditions are first baked at 65°C for 1min, and then baked at 95°C Bake for 15 minutes to promote the cross-linking reaction in the exposed areas of the negative photoresist.

1.1.6 Development: after post-baking, the glue in the non-exposed area of the negative photoresist is removed by a developer to obtain a channel pattern opposite to the mask, that is, to obtain a silicon wafer with a microchannel pattern. Here, the silicon wafer is also referred to as the male mold, Figure 3d.

1.1.7 Hard mold: In order to increase the adhesion between the rubber mold and the silicon substrate, the positive mold obtained after the development needs to be baked at 65°C for 2 hours.

1.1.8 Pouring glue: After mixing polydimethylsiloxane (PDMS) monomer and curing agent at a ratio of 10:1, degas to obtain a transparent prepolymer without bubbles; then pour the prepolymer into the prepolymer On the male mold with the cofferdam structure, Figure 3e. Immediately transfer to a hot plate or a constant temperature heating box for heating, the heating temperature is 65 ° C, and the time is 3 hours, so that the prepolymer is completely cured.

1.1.9 Demoulding and punching: Carefully peel off the cured PDMS with a microchannel structure (that is, the concave part of the substrate) from the male mold, as shown in Figure 3f, and then use a puncher to punch holes to form a liquid inlet channel, that is, Substrate 20.

It can be understood that in other embodiments, in step 1.1.1, the silicon wafer used can be replaced by glass, metal, etc.

In step 1.1.2, in the step of uniform coating, a certain thickness of negative photoresist can also be coated on the silicon wafer by methods such as brushing and spraying.

In step 1.1.4, the exposure process is not limited to using a photolithography machine, and the photolithography process can also be carried out by other methods.

A photomicrograph of the glass-based microfluidic chip fabricated by the method for manufacturing the above-mentioned glass-based microfluidic chip is shown in FIG. 4 .

Randomly take points on the first microchannel and the second microchannel of the fabricated glass-based microfluidic chip for measurement, the obtained average width is 73 μm, and the relative standard deviation (RSD) is 0.03%. This shows that the prepared glass-based microfluidic chip microchannel has high uniformity in width and high processing quality. At the same time, it can also be observed that the structure of the first microchannel is relatively complete.

comparative example

This comparative example is a method for manufacturing a glass-based microfluidic chip, the steps of which are the same as those in the embodiment, the difference being that in step (3), the temperature is raised to above the annealing temperature of the glass at an average heating rate of 5°C/min (600°C). .

Compared with the first microchannel of the prepared glass-based microfluidic chip at the same position in the example, it was found that the first microchannel of the comparative example was seriously deformed, forming a bulging bubble, which not only caused the chip The unevenness of the surface also causes distortion and deformation of the nearby second microchannel.

The various technical features of the above-mentioned embodiments can be combined arbitrarily. To make the description concise, all possible combinations of the various technical features in the above-mentioned embodiments are not described. However, as long as there is no contradiction in the combination of these technical features, should be considered as within the scope of this specification.

The above-mentioned embodiments only express several implementation modes of the present invention, and the descriptions thereof are relatively specific and detailed, but should not be construed as limiting the patent scope of the invention. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent for the present invention should be based on the appended claims.

Claims (9)

1. a kind of production method of glass base chip, which is characterized in that the glass base chip interior has microchannel, described micro- Channel includes several first microchannels, and first microchannel is closed chamber；

The production method includes the following steps:

Obtain bottom sheet glass and cover glass piece；

The microchannel is formed after the cover glass piece is fitted in the bottom sheet glass, obtains adhesive piece；

The adhesive piece is transferred in heating device, the annealing temperature of glass is warming up to the heating rate of 0.5~2 DEG C/min More than；Then annealed cooling process again, obtains the glass base chip；

The method of the heating are as follows: be warming up to 545~555 DEG C with the heating rate of 0.9~1.1 DEG C/min, and 545~555 55~65min is kept the temperature at DEG C；Then 595~605 DEG C are warming up in 55~65min, and at 595~605 DEG C heat preservation 175~ 185min。

2. the production method of glass base chip according to claim 1, which is characterized in that the heating rate be 0.8~ 1.5℃/min。

3. the production method of glass base chip according to claim 1, which is characterized in that the annealing cooling process be with The Mean Speed of 1~3 DEG C/min is down to room temperature.

4. the production method of glass base chip according to claim 1, which is characterized in that the microchannel further includes several Second microchannel；Second microchannel has several openings being connected with atmosphere.

5. the production method of glass base chip according to claim 1-4, which is characterized in that the bottom sheet glass Surface etch have recessed portion, after the cover glass piece is fitted in the surface, between the recessed portion and the cover glass piece Form the microchannel；

The method for obtaining the bottom sheet glass includes the following steps:

Substrate is obtained, is etched with substrate recessed portion on the substrate, and offer the feed liquor being connected with the substrate recessed portion Mouthful；The substrate recessed portion is corresponding with the recessed portion that the bottom glass sheet surface etches；

The substrate and sheet glass are subjected to reversible keying, the surface formation chamber of the substrate recessed portion and sheet glass；

Etching liquid is injected from the inlet to the chamber, the sheet glass is performed etching, i.e. the table in the sheet glass Face forms the recessed portion；

The substrate is removed to get the bottom sheet glass.

6. the production method of glass base chip according to claim 5, which is characterized in that the etching liquid includes volume Than the hydrofluoric acid, nitric acid and water for 1:1~3:15~25.

7. the production method of glass base chip according to claim 5, which is characterized in that the material of the substrate is poly- two One of methylsiloxane, polymethyl methacrylate, polycarbonate or multiple combinations.

8. according to the production method of the described in any item glass base chips of claim 5-7, which is characterized in that by the substrate with After the sheet glass carries out reversible keying, heated baking is carried out to gained chip, baking temperature is 60~70 DEG C, and the time is 1~3 Hour.

9. the prepared glass base chip of production method of the described in any item glass base chips of claim 1-8.