CN109985673B - Microfluidic Chip - Google Patents

Abstract

The invention discloses a microfluidic chip, which comprises a substrate, wherein the substrate is provided with at least one reaction cavity, and a sample inlet and a gas outlet which are respectively communicated with the reaction cavity through micro channels; the cover plate is fixedly combined on the surface of the substrate and seals the reaction cavity and the micro-channel; the side wall of the reaction cavity is of a ladder structure, and the area of the bottom surface of the reaction cavity is smaller than the area of the opening of the top surface of the reaction cavity. By arranging the step structure on the side wall of the reaction cavity of the microfluidic chip, the reagent is prevented from diffusing into the micro-channel during sample application and freeze-drying, the blockage of the micro-channel after freeze-drying is avoided, and the smooth and accurate sample adding operation of subsequent experiments is ensured.

Description

Microfluidic Chip

Technical Field

The present invention relates to the field of microfluidics technology, and more specifically, to a microfluidics chip.

Background technique

Microfluidic chips are the main platform for the realization of microfluidic technology. Microfluidic chips refer to the integration of basic operating units such as sample preparation, reaction, separation, and detection involved in the fields of chemistry and biology on a very small chip. Microchannels form a network and controllable fluids run through the entire system to achieve various functions of conventional chemical or biological laboratories. Microfluidic chips can quickly and accurately divide samples into several independent units and perform multi-step parallel reactions. They are low-cost, small in size, and high in throughput.

There are two main types of common PCR microfluidic chips: micro-reaction chamber type and continuous flow type. Micro-reaction chamber PCR chip refers to a cavity processed on the chip to store experimental reagents. The cavity is heated and cooled by heating and cooling devices to reach the temperature required for each stage of PCR amplification, and an amplification process is completed after one temperature cycle.

Fluorescence quantitative PCR amplification reaction reagents are required to be stored, transported and used under low temperature conditions, otherwise the diagnostic reagents are prone to failure. Therefore, the long-term storage and long-distance transportation of the test kit will be greatly limited. The sensitivity of the diagnostic reagents may decrease or even fail completely due to improper storage, which will eventually lead to the untimely detection of the disease and cause the epidemic. Therefore, at present, after adding the reagents to the reaction chamber, the reagents are usually cooled and frozen into a solid, and then sublimated under vacuum conditions to evaporate more than 95% of the water. The protective agent will not collapse during sublimation as a solid, ensuring the morphology of the freeze-dried product, so that the freeze-dried reagents are retained in the reaction chamber, so that the microfluidic chip can be stored and transported at room temperature. However, the inventors found that after adding the reagents to the reaction chamber, the liquid reagents will diffuse along the microchannels connected to the reaction chamber, resulting in a reduction in the amount of freeze-dried reagents remaining in the reaction chamber. In more serious cases, the microchannels will be blocked, and the sample liquid cannot be added to the reaction chamber.

Summary of the invention

The object of the present invention is to provide a microfluidic chip, the reaction chamber of which can prevent the reagent from diffusing into the microchannel, thereby making the amount of the freeze-dried reagent in the reaction chamber accurate and also ensuring smooth sample addition.

According to one aspect of the present invention, there is provided a microfluidic chip, comprising:

A substrate, wherein the substrate is provided with at least one reaction chamber, and an inlet and an outlet respectively connected with the reaction chamber through microchannels;

A cover sheet, the cover sheet is fixedly bonded to the surface of the substrate to seal the reaction chamber and the microchannel;

The side wall of the reaction chamber is arranged in a stepped structure, and the bottom surface area of the reaction chamber is smaller than the area of the top surface opening thereof.

Preferably, the stepped structure of the reaction chamber side wall includes a layer of stepped structure, and the stepped structure divides the reaction chamber side wall into an upper side wall and a lower side wall, and the upper side wall and the lower side wall respectively enclose an upper chamber and a lower chamber, and the cross-sectional area of the upper chamber is larger than the cross-sectional area of the lower chamber.

Preferably, the depth of the upper chamber is smaller than the depth of the lower chamber.

Preferably, the upper side wall enclosed to form the upper chamber is subjected to a hydrophobic treatment, and the lower side wall and bottom wall enclosed to form the lower chamber are subjected to a hydrophilic treatment.

Preferably, the reaction chamber is arranged in a racetrack shape, including an arc side and a straight side which are arranged opposite to each other.

Preferably, the microchannels are respectively connected to the arc sides at both ends of the reaction chamber.

Preferably, the one-layer step structure is arranged on the side wall of the arc side of the reaction chamber.

Preferably, the air outlet is covered with a water-proof and breathable membrane.

Preferably, the substrate is staggeredly provided with a plurality of reaction chambers, and the plurality of reaction chambers are respectively connected with the sample inlet and the gas outlet through respective microchannels.

Preferably, the multiple reaction chambers are connected to the buffer chamber through respective microchannels, and the buffer chamber is connected to the injection port.

The beneficial effects of the present invention are as follows:

By arranging a step structure on the side wall of the reaction chamber of the microfluidic chip of the present invention, the step structure can prevent the reagent from diffusing into the microchannel during sample application and freeze drying, avoid microchannel blockage after freeze drying, reduce the loss rate of freeze-dried reagents, ensure a 100% sample application success rate, and enable subsequent experiments to proceed smoothly.

BRIEF DESCRIPTION OF THE DRAWINGS

The specific implementation modes of the present invention will be further described in detail below in conjunction with the accompanying drawings.

FIG1 shows a schematic diagram of the exploded structure of the present invention.

FIG. 2 is a schematic diagram showing an enlarged structure of part A of the present invention.

FIG. 3 is a schematic structural diagram of a substrate according to another embodiment of the present invention.

FIG. 4 is a schematic structural diagram of another embodiment of the present invention.

Detailed ways

In order to more clearly illustrate the present invention, the present invention is further described below in conjunction with preferred embodiments and accompanying drawings. Similar components in the accompanying drawings are represented by the same reference numerals. It should be understood by those skilled in the art that the content specifically described below is illustrative rather than restrictive, and should not be used to limit the scope of protection of the present invention.

As shown in Figures 1-4, an embodiment of the present invention provides a microfluidic chip, which includes a cover sheet 1 and a substrate 2, on which at least one reaction chamber 21 is provided, as well as an inlet 22 and an outlet 23 respectively connected to the reaction chamber 21 through microchannels. The cover sheet 1 is fixedly bonded to the surface of the substrate 2 to seal the reaction chamber 21 and the microchannel. The reaction chamber 21 and the microchannel can be formed on one side surface of the substrate 2 by a micromachining process, and the cover sheet 1 is fixedly bonded to the side surface of the substrate 2 by bonding, thereby sealing the reaction chamber 21 and the microchannel. The substrate 2 can be made of silicon, glass or an organic compound, and the reaction chamber 21 and the microchannel are formed by wet chemical etching, dry plasma etching or a combination of the two, which is a conventional technical means in the art and will not be repeated here.

The microfluidic chip of the present invention has a structure of fixed amplification in a reaction pool, in order to prevent the fluorescent quantitative PCR reagent from diffusing along the microchannel connected to the reaction chamber 21 when the reagent is added to the reaction chamber 21 for freeze drying. The side wall of the reaction chamber 21 is set as a stepped structure, and the bottom area of the reaction chamber is smaller than the area of the top opening.

Specifically, as shown in FIG2 , in this embodiment, the reaction chamber 21 and the microchannel are formed by etching on the surface of the substrate 2. Since the PCR reaction requires that there should be no air residue, the shape of the reaction chamber 21 in this embodiment is set to a runway shape. The arc structure of the reaction chamber of this shape adapts to the surface tension of the liquid. During the sample addition operation, the liquid is spread in the reaction chamber along the arc side wall, and no air will remain. Other structures are prone to dead angles, resulting in gas residue and air remaining in the reaction chamber, which affects the PCR reaction.

The reaction chamber 21 includes an arc side and a straight side that are arranged oppositely. The microchannel is located on both sides of the reaction chamber 21, one end of which is respectively connected to the arc side, and the other end of which is respectively connected to the injection port 23 and the gas outlet 23. The step structure of the side wall of the reaction chamber 21 includes a step structure, which divides the side wall of the reaction chamber into an upper side wall and a lower side wall. The upper side wall and the lower side wall are respectively enclosed to form an upper chamber 24 and a lower chamber 25, that is, the upper chamber 24 and the lower chamber 25 together form the reaction chamber 21. The cross-sectional area of the upper chamber 24 is larger than the cross-sectional area of the lower chamber 25. When the reagent is added to the reaction chamber 21, it is located in the lower chamber. Due to the surface tension on the contact surface of the liquid, gas, and solid, the liquid will climb along the side wall of the reaction chamber. When the liquid reagent is freeze-dried, since the step structure of the side wall of the reaction chamber 21 has the effect of blocking the liquid from climbing, the step structure is equivalent to adding a retaining wall to the reagent, preventing the occurrence of capillary phenomenon. The stepped structure can prevent the liquid from climbing along the side wall, and the liquid reagent is difficult to diffuse along the side wall of the reaction chamber 21, and the reagent cannot diffuse into the microchannel, thereby ensuring the amount of reagent remaining in the lower chamber 25. Ultimately, all liquid reagents are retained in the lower chamber 25 after freeze-drying.

Furthermore, since one end of the microchannel in this embodiment is connected to the arc side of the reaction chamber 21, the step structure is only provided on the arc side of the racetrack-shaped reaction chamber 21, that is, the step structure is only provided at both ends of the reaction chamber 21. This structure can increase the volume of the lower chamber 25 while making it difficult for the reagent to diffuse into the microchannel.

In order to reduce the difficulty of chip processing and improve the chip yield, in this embodiment, the step structure only includes one layer of step structure. In another embodiment, the step structure may include multiple layers of step structure, so that the reaction chamber 21 also includes multiple chambers.

Furthermore, in order to better prevent the reagent from diffusing into the microchannel, in the present embodiment, the depth of the upper chamber 24 is less than the depth of the lower chamber 25, the upper side wall enclosed to form the upper chamber 24 is subjected to a hydrophobic treatment, and the lower side wall and bottom wall enclosed to form the lower chamber 25 are subjected to a hydrophilic treatment, so that the reagent is more easily stored in the hydrophilic layer and is not easily diffused into the hydrophobic layer, and therefore it is more difficult for the reagent to diffuse into the microchannel.

Furthermore, the sample inlet 22 and the gas outlet 23 penetrate the substrate 2 and are connected to the microchannel respectively. After the reagent is freeze-dried, the cover sheet 1 is fixedly combined with the substrate 2, and the reaction chamber 21 and the microchannel, as well as the one side openings of the sample inlet 22 and the gas outlet 23 are closed. To ensure that the sample can be evenly distributed in each reaction chamber when adding the sample, a hydrophobic breathable membrane 3 is covered and pasted on the gas outlet 23. When using the microfluidic chip of the present invention, it is only necessary to add the template to be tested to the sample inlet 22 to conduct the machine detection. During operation, the template to be tested is added to the sample inlet 22, and the template to be tested enters the reaction chamber 21 through the microchannel to react with the freeze-dried reagent. The air in the reaction chamber 21 and the microchannel is discharged through the gas outlet 23, and then the machine is tested. The operation is simple and does not require professional operation.

In another embodiment of the present invention as shown in FIGS. 3 and 4 , the surface of the substrate 2 is etched to have a plurality of reaction chambers 21 and a plurality of gas outlets 23, the plurality of reaction chambers 21 are arranged in a staggered manner, and each reaction chamber 21 is connected to a corresponding gas outlet 23 through its own microchannel. One injection port 22 is provided, which is connected to the plurality of reaction chambers through microchannels. This structure can process the templates to be tested in parallel, greatly improving the detection speed.

Furthermore, a buffer cavity 26 is etched on the surface of the substrate 2, one end of which is connected to the injection port 22, and the other end of which is connected to the plurality of reaction cavities 21 through microchannels. The buffer cavity 26 can ensure that the template to be tested continuously and stably enters the reaction cavity 21, thereby improving the accuracy of the test.

Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not limitations on the implementation methods of the present invention. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is impossible to list all the implementation methods here. All obvious changes or modifications derived from the technical solution of the present invention are still within the protection scope of the present invention.

Claims (9)

1. A microfluidic chip, comprising: A substrate, wherein the substrate is provided with at least one reaction chamber, and an inlet and an outlet respectively connected with the reaction chamber through microchannels; A cover sheet, the cover sheet is fixedly bonded to the surface of the substrate to seal the reaction chamber and the microchannel; It is characterized in that the side wall of the reaction chamber is arranged as a stepped structure, and the bottom area of the reaction chamber is smaller than the area of its top opening; the stepped structure of the side wall of the reaction chamber includes a layer of stepped structure, and the step structure divides the side wall of the reaction chamber into an upper side wall and a lower side wall, and the upper side wall and the lower side wall are respectively enclosed to form an upper chamber and a lower chamber, the cross-sectional area of the upper chamber is larger than the cross-sectional area of the lower chamber, and the microchannel is connected to the upper chamber. 2 . The microfluidic chip according to claim 1 , wherein the depth of the upper chamber is smaller than the depth of the lower chamber. 3. The microfluidic chip according to claim 1 is characterized in that the upper side wall enclosed to form the upper chamber is subjected to hydrophobic treatment, and the lower side wall and bottom wall enclosed to form the lower chamber are subjected to hydrophilic treatment. 4 . The microfluidic chip according to claim 1 , wherein the reaction chamber is arranged in a racetrack shape, including an arc side and a straight side which are arranged opposite to each other. 5 . The microfluidic chip according to claim 4 , wherein the microchannel is connected to the arc sides at both ends of the reaction chamber respectively. 6 . The microfluidic chip according to claim 5 , wherein the one-layer step structure is arranged on the side wall of the arc side of the reaction chamber. 7 . The microfluidic chip according to claim 1 , wherein the air outlet is covered with a water-proof and breathable membrane. 8 . The microfluidic chip according to claim 1 , wherein the substrate is staggeredly provided with a plurality of reaction chambers, and the plurality of reaction chambers are respectively connected to the sample inlet and the gas outlet through respective microchannels. 9 . The microfluidic chip according to claim 8 , wherein the plurality of reaction chambers are connected to a buffer chamber through respective microchannels, and the buffer chamber is connected to the injection port.