LATERAL-FLOW MICROFLUIDIC CHIP AND FLOW VELOCITY CONTROL METHOD THEREOF

Abstract

The present disclosure relates to a method of accelerating a flow velocity in a lateral-flow microfluidic chip in which an analysis time is not delayed while sequential reactions are possible in the lateral-flow microfluidic chip by accelerating a flow velocity in at least a section of a channel, it is easy to manufacture the microfluidic chip for applying the method, and it is possible to mass-produce the microfluidic chip, and more particularly, by increasing a vapor pressure around a specific channel, a flow velocity of a fluid in the corresponding channel is accelerated.

Claims

1. A method of controlling a flow velocity in a lateral-flow microfluidic chip, the method comprising: increasing a vapor pressure around at least a part of a channel.

2. The method of claim 1, wherein the increasing of the vapor pressure includes: forming a liquid reservoir around at least a portion of the channel; and filling the liquid reservoir with a liquid.

3. The method of claim 2, wherein the increasing of the vapor pressure further includes adjusting the increased vapor pressure by changing a concentration of the liquid with which the liquid reservoir is filled.

4. The method of claim 2, wherein the increasing of the vapor pressure further includes adjusting the increased vapor pressure by deforming a shape of the liquid reservoir.

5. A lateral-flow microfluidic chip, comprising: a channel in which a sample flows; and a liquid reservoir formed at a side of at least a part of the channel.

6. The lateral-flow microfluidic chip of claim 5, wherein the liquid reservoir is separated from the channel.

7. The lateral-flow microfluidic chip of claim 5, wherein the liquid reservoir is a sample pad.

8. The lateral-flow microfluidic chip of claim 5, wherein a degree of acceleration is adjusted by a gap between the channel and the liquid reservoir.

9. The lateral-flow microfluidic chip of claim 5, wherein a degree of acceleration is adjusted by a width of the liquid reservoir.

10. The lateral-flow microfluidic chip of claim 5, wherein a degree of acceleration is adjusted by a type of liquid contained in the liquid reservoir.

11. The lateral-flow microfluidic chip of claim 7, wherein an acceleration time is adjusted in accordance with a capacity of the liquid reservoir.

12. The lateral-flow microfluidic chip of claim 5, wherein the liquid reservoir is formed at both sides of the corresponding channel.

13. The lateral-flow microfluidic chip of claim 7, wherein the microfluidic chip is a chip for sample analysis by enzyme linked immunosorbent assay (ELISA).

14. The lateral-flow microfluidic chip of claim 7, wherein the microfluidic chip is a paper chip in which a channel is formed by printing a wax pattern having a shape of a boundary of the channel on a sheet of paper and then heat-treating the wax pattern.

15. The lateral-flow microfluidic chip of claim 5, wherein the liquid reservoir is formed at a side of at least some of a plurality of channels.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The above and other objects, features and advantages of the present invention will become more apparent to those of ordinary skill in the art by describing exemplary embodiments thereof in detail with reference to the accompanying drawings, in which:

[0029] FIGS. 1A-1 to 1C-2 illustrate design and three-dimensional schematic diagrams of a paper chip in which a liquid reservoir is formed according to an example and conventional paper chip;

[0030] FIGS. 2A-1 to 2C illustrate photographs and graphs that show a flow velocity in the paper chip in accordance with whether the liquid reservoir is formed in the example of FIGS. 1A-1 to 1C-2;

[0031] FIGS. 3A and 3B illustrate graphs that show an influence of a gap between the liquid reservoir and a channel on the flow velocity;

[0032] FIG. 4 illustrates an image that shows an influence of a vapor pressure of a liquid contained in the liquid reservoir on the flow velocity;

[0033] FIGS. 5A and 5B illustrate design of a paper chip in which a liquid reservoir is formed according to another example;

[0034] FIGS. 6A-1 to 6B illustrate photographs and graphs that show a flow velocity in the paper chip in accordance with whether the liquid reservoir is formed in the example of FIGS. 5A and 5B; and

[0035] FIG. 7 illustrates a schematic diagram of a paper chip for the ELISA of the related art.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

[0036] The present disclosure will be described in more detail below with reference to the appended examples. However, such examples are merely examples for easily describing the technical idea and the scope of the present disclosure, and the technical scope of the present disclosure is not limited or changed by such examples. It should be apparent to those of ordinary skill in the art that various modifications and changes may be made within the scope of the technical idea of the present disclosure on the basis of such examples.

EXAMPLES

Example 1: Check Acceleration of Fluid in Paper Chip to which Liquid Reservoir is Adopted

[0037] 1) Check Influence of Liquid Reservoir on Flow Velocity

[0038] It was predicted that a flow velocity would increase in a paper chip when a liquid reservoir is placed at both sides of a channel and a vapor pressure is selectively increased in the channel, and this was confirmed through an experiment.

[0039] For the confirmation, on a sheet of Whatman 3MM chromatography paper, a circular sample injecting portion having a diameter (inner diameter) of 12 mm and a shape of a channel which is connected to the injecting portion and has a width of 2 mm and length of 60.5 mm were designed using Adobe Illustrator CS6 program. A liquid reservoir having a width of 12.5 mm and a length of 57.2 mm was designed to be disposed at both sides of the channel at a distance of 1.5 mm from the channel. For the comparison of flow velocities, a paper chip in which the liquid reservoir is not formed was also designed. On a bottom end of an injection port, a circular support plate was printed to prevent leakage of a sample to the outside through a bottom end of the paper during injection of the sample. Also, a sample pad ring which is concentric with the injection port and has a diameter of 11.5 mm which is smaller than that of the injection port was designed to be included in the injection port of the sample. In this way, the sample was prevented from coming into direct contact with the channel during the injection of the sample.

[0040] FIG. 1A-1 shows design of a front surface and FIG. 1A-2 shows a rear surface of the paper chip in which the liquid reservoir is formed according to the present example, and FIG. 1B shows design of a front surface of the conventional paper chip in which the liquid reservoir is not formed according to the related art. The patterns of the designs were printed using a wax printer (Xerox ColorQube 8570) such that the shape of the channel at the front and rear surfaces was printed with wax, and the sample pad ring was printed. Then, by heat-treating the patterns at Speed 2 at 160 C. using a laminator (PhotoLami-350R10), the wax printed on the front surface and the rear surface was caused to penetrate the sheet of paper and form a closed channel. FIG. 1C-1 illustrates three-dimensional schematic diagrams of a paper chip in which the liquid reservoir manufactured by the above method is formed. FIG. 1C-2 shows a paper chip without the liquid reservoir.

[0041] The paper chip manufactured by the above method was fixed to be horizontally arranged, and 1,500 l of distilled water was dropped on each liquid reservoir by using a pipette. 120 l of distilled water was simultaneously dropped on five sample pads by using a pipette, and a time at which the fluid reached an end of a channel was measured. FIGS. 2A-1 to 2B-2 is a photograph showing a flow velocity in the paper chip in accordance with whether the liquid reservoir is formed, and FIG. 2C is a graph showing a time taken for the fluid to reach the end of the channel. As seen in FIG. 2C, while the fluid reached the end of the channel in an average of 18 minutes 49 seconds in the paper chip of the related art to which the liquid reservoir is not adopted, the fluid reached the end of the channel in 12 minutes 8 seconds in the paper chip to which the liquid reservoir is adopted. That is, it was confirmed that, due to adoption of the liquid reservoir, the fluid reached the end of the channel 6 minutes 41 seconds faster, and the flow velocity increased by about 1.55 times. This is considered to be due to a decrease in an evaporation rate of a fluid in a channel which is due to an increase in humidity level of a section of the paper chip caused by the liquid reservoir.

[0042] 2) Check Influence of Gap Between Liquid Reservoir and Channel on Flow Velocity

[0043] To check the influence of the gap between the liquid reservoir and the channel on the flow velocity, a flow time was measured by the same method as in 1) with respect to the gaps were changed, from the design of the channel in 1), to be 1.5 mm, 5 mm, 9 mm, and 13 mm. FIG. 3A is a graph showing a travel distance of a fluid with time and a time taken for the fluid to reach the end of the channel in each channel. And it can be seen from FIG. 3B that the flow velocity of the fluid is higher as the gap between the liquid reservoir and the channel is narrower. In the channels which are distant from the liquid reservoir at 1.5 mm, 5 mm, 9 mm, and 13 mm, the times taken for the fluid to reach the end of the channel were 606 seconds, 665 seconds, 755 seconds, and 788 seconds, respectively.

[0044] 3) Check Influence of Type of Liquid Contained in Liquid Reservoir on Flow Velocity

[0045] To check the influence of the type of liquid contained in the liquid reservoir on the flow velocity, sugar water having different concentrations was poured into the liquid reservoir of the paper chip manufactured in 1), and a flow velocity of a fluid was measured. Except for injecting sugar water having concentrations of 400, 800, and 1600 g/L instead of water in the liquid reservoir, the flow velocity was measured by the same method as in 1). FIG. 4 is an image showing a travel distance 25 minutes after sample injection, and it can be seen from FIG. 4 that the travel distance of the fluid is shorter during the same time as the concentration of sugar is higher. Since the boiling point increases and the vapor pressure decreases as the concentration of sugar is higher, the above result indicates that a degree of acceleration may be adjusted in accordance with a vapor pressure property of a liquid contained in the liquid reservoir.

Example 2: Check Acceleration of Fluid in Paper Chip in which Sample Pad is Utilized as Liquid Reservoir

[0046] To eliminate an inconvenience of having to separately pour a liquid into a separately-formed liquid reservoir as in Example 1, usefulness of design of a channel of a paper chip in which a sample pad itself may be used as a liquid reservoir was confirmed. FIG. 5A is a conceptual diagram of a channel of the paper chip in which a sample pad serves as a liquid reservoir, and FIG. 5B show designs of a front surface of a sheet of paper using Adobe Illustrator CS6 program. The method of manufacturing the paper chip is the same as that in Example 1, and numerical values used in the design are indicated in Table 1.

TABLE-US-00001 TABLE 1 Element Size Channel width 2 mm Gap 1 mm Sample pad 13 mm*26 mm

[0047] To facilitate observation of the flow of the fluid in the completed paper chip, 2 l of magenta ink was adsorbed onto a corner of left path, 2 l of cyan ink was adsorbed onto a corner of right path, and then the adsorbed ink was dried. The paper chip in which the ink was dried was fixed to be horizontally arranged, 800 pi of distilled water was dropped on each sample pad by using a pipette, and the flow of the fluid was observed. FIGS. 6A-1 to 6A-4 are photographs of the paper chip with time, and FIG. 6B is a graph showing time taken for the fluid to reach the end of each channel. As it can be seen in FIGS. 6A-1 to 6B, an average time taken for the fluid to reach the end of the channel was 22 minutes 17 seconds along the right path and 25 minutes along the left path, and thus was about 2 minutes 43 seconds faster along the right path. This indicates that the sample pad may simultaneously serve as the liquid reservoir and accelerate the flow of the fluid in an adjacent channel. As indicated by Example 2 above, in the present disclosure, the sample pad may be used as the liquid reservoir and may selectively accelerate a flow velocity in some or all of a plurality of channels.

[0048] Meanwhile, the shape of the liquid reservoir may be deformed in various ways to adjust the flow velocity. Although an example in which the liquid reservoir has a rectangular shape that abuts a wall of the channel has been described above with reference to the above examples, the shape of the liquid reservoir is not limited thereto, and the liquid reservoir may have a circular, triangular, square, pentagonal, or any arbitrary shape.

[0049] Since a portion of the liquid reservoir which is the closest to the channel has the greatest influence on acceleration of a fluid, the flow velocity in the channel may be adjusted by adjusting a region in the vicinity of the channel while deforming the shape of the liquid reservoir.

[0050] And the total capacity of the liquid reservoir determines the acceleration time, as well as the amount of liquid in the liquid reservoir.

[0051] The present disclosure has been described above with reference to a few examples, but it should be apparent to those of ordinary skill in the art that various modifications and changes are possible within the scope of the technical idea of the present disclosure. The scope of the present disclosure is not limited by the above description and examples, and is defined by the claims below.