JP7470288B2 - Microfluidic Devices - Google Patents

Description

This invention relates to a microfluidic device.

Traditionally, cell and tissue culture has been performed using culture dishes or plates with agar or medium. Since cell and tissue culture using these culture dishes or plates is performed in a two-dimensional (flat) environment, it is not possible to reproduce the extracellular microenvironment. Therefore, in recent years, microfluidic devices (also called "cell culture chips," "biochips," or "microchips") have been proposed that have microchannels that can create three-dimensional (solid) cell culture and experimental environments, which was difficult to achieve using conventional methods.

For example, Patent Document 1 describes a microfluidic device in which two substrates are bonded together, and a flow channel is formed by a step formed in at least one of the substrates, which is surrounded by the junction between the two substrates.

Incidentally, it is known to provide an assembly in which multiple analysis plates are housed in a holder to an analysis device (see Patent Document 2). The holder has recesses that correspond to protrusions provided on the side of the analysis plate, and the analysis plate is fixed to the holder by fitting the protrusions into the recesses.

JP 2019-078707 A JP 2019-105528 A

There is a demand for a microfluidic device in which a plate having a microchannel formed by bonding multiple substrates is housed in a holder. If the microfluidic device housing the plate in the holder could be placed on the table of a dispensing device, it would be easier to handle.

However, when such a microfluidic device is placed on the table of a dispensing device and an attempt is made to inject fluid from the pipette tip of the dispensing device into an opening in the plate, the position of the pipette tip may shift relative to the position of the opening.

Now, let us explain the misalignment of the pipette tip. Usually, the dispensing device is automated. The dispensing device stores the opening position of the microfluidic device placed at a specified position, and moves the pipette tip to the stored opening position to perform the dispensing operation. However, if the position of the opening relative to the dispensing device is misaligned, the destination of the pipette tip will be misaligned from the opening position. This can result in a problem that the fluid in the pipette tip cannot be injected into the microchannel, or that when attempting to insert the tip of the pipette tip into the opening to inject the fluid, the pipette tip collides with the surface of the plate, damaging the pipette tip and/or the plate.

The inventors analyzed the cause of the misalignment of the plate's opening relative to the dispensing device and found that the opening's position was not fixed even when the plate was positioned relative to the holder using the side of the plate in the microfluidic device. The cause of this will be explained with reference to Figures 24 and 25.

Figure 24 shows a cross-sectional view of a microfluidic device. The microfluidic device 500 is configured by housing a plate 91, which is made up of a first substrate 92 and a second substrate 93 joined together, each substrate having an opening 94 formed therein for injecting a fluid, in a holder 95. The inner dimensions of the holder 95 are designed to be slightly larger than the dimensions of the plate 91 so that the plate 91 can be easily housed inside the holder 95.

To fix the position of the opening 94 of the plate 91 relative to the dispensing device, the plate 91 must be positioned at a predetermined position relative to the holder 95. The plate 91 is positioned by pressing the outer surface of the plate 91 against the inner wall surface 97 of the holder 95, which serves as the reference. Then, the distance from the edge of the microfluidic device 500 to the center of the opening 94 becomes the preset value M1.

However, among the plates, there are plates in which the first substrate and the second substrate are bonded in a misaligned manner. FIG. 25 shows a cross-sectional view of a microfluidic device different from that shown in FIG. 24. The plate 99 housed in the microfluidic device 600 shown in FIG. 25 shows an example of such a plate. In order to position the plate 99 at a predetermined position relative to the holder 95, the outer surface of the plate 99 is pressed against the inner wall surface 97, which serves as the reference for the holder 95. However, since the second side surface 93c of the second substrate 93 contacts the inner wall surface 97, a gap d1 is generated between the first side surface 92c of the first substrate 92 and the inner wall surface 97. As a result, the distance from the end of the microfluidic device 600 to the center of the opening 94 becomes M1+d1, which is deviated from the default value by the amount of the gap d1.

In other words, it was found that the misalignment of the plate's opening relative to the dispensing device was caused by the misalignment of the substrates that make up the plate. Based on the results of this analysis, the present invention aims to provide a microfluidic device that can position pipette tips with high precision.

The microfluidic device of the present invention includes a plate having a first substrate having a first main surface in which an opening for injecting a fluid is formed, a second main surface opposite to the first main surface, and a first side surface connecting the first main surface and the second main surface, and a second substrate bonded to the second main surface;
a holder having an inner wall surface surrounding the outer surface of the plate while being spaced apart from the outer surface of the plate, and a lower surface on which the second substrate of the plate is placed;
The substrate further includes a protrusion formed on a partial area of a surface of at least one of the first substrate and the holder, protruding from the surface in a direction in which the first substrate and the holder face each other to bring the first substrate and the holder into contact with each other.

As will be described in detail later, rather than bringing the entire plate consisting of the first and second substrates into contact with the holder, the first substrate is brought into contact with the holder by using a protrusion. This allows the first substrate to be positioned with high precision relative to the holder. Furthermore, because the opening is provided in the first substrate, positioning the first substrate with high precision relative to the holder prevents the position of the opening from shifting from a specified position.

The recess into which the protrusion is fitted may be formed in a partial area of the surface of at least one of the first substrate and the holder.

The protrusions may include at least two protrusions that protrude from the inner wall surface or the first side surface extending in a first direction in a second direction perpendicular to the first direction, and at least one protrusion that protrudes in the first direction from the inner wall surface or the first side surface extending in the second direction.

The holder includes an elastic body that contacts a partial area of the first side surface,
The first side surface with which the elastic body comes into contact may be located at a position facing the protruding portion with the second substrate interposed therebetween.

the microfluidic device includes an upper frame that is fitted inside the holder, exposes the openings formed in the first main surface of the first substrate, and covers an outside of an area of the first main surface where the openings are formed;
A portion of the frame bottom of the upper frame may have a second protruding portion that protrudes from the frame bottom and contacts the first side surface of the first substrate.

The upper frame may have a liquid storage tank.

The microfluidic device may be used for cell or tissue culture.

This makes it possible to provide a microfluidic device that can position pipette tips with high precision.

FIG. 1 is a perspective view of a first embodiment of a microfluidic device. FIG. FIG. 3 is a cross-sectional view taken along line A1-A1 in FIG. 2. FIG. 6 is a cross-sectional view taken along line B1-B1 in FIG. 5. FIG. 2 is an enlarged top view of area A2 of FIG. 1. 8 is a cross-sectional view taken along line C1-C1 in FIG. 7. 8 is a cross-sectional view taken along line C2-C2 in FIG. 7. 1 shows a modified version of the plate. 1 shows a first variant of a positioning element; 4 shows a second variant of the positioning element. 4 shows a third variant of the positioning element. 4 shows a fourth variant of the positioning element. 14 is a cross-sectional view taken along line C3-C3 in FIG. 13. FIG. 13 is a top view of a fifth variant of the positioning element. 16 is a cross-sectional view taken along line C4-C4 in FIG. 15. 13 shows a sixth variant of the positioning element. FIG. 2 is a top view of a second embodiment of a microfluidic device. 19 is a cross-sectional view taken along line B2-B2 of FIG. 18. FIG. 13 is a perspective view of a third embodiment of a microfluidic device. An oblique view of the upper frame. 21 is a cross-sectional view taken along line B3-B3 in FIG. 20. FIG. 22B is a schematic diagram showing the assembly of the microfluidic device shown in cross-section in FIG. 22A. 21 is a cross-sectional view taken along line B4-B4 in FIG. 20. FIG. 23B is a schematic diagram showing the assembly of the microfluidic device shown in cross-section in FIG. 23A. 1A and 1B are diagrams for explaining the cause of a conventionally occurring positional deviation of an opening. 1A and 1B are diagrams for explaining the cause of a conventionally occurring positional deviation of an opening.

Embodiments of the microfluidic device will be described with reference to the drawings. Note that the drawings disclosed in this specification are merely schematic illustrations. In other words, the dimensional ratios in the drawings do not necessarily match the actual dimensional ratios, and the dimensional ratios between the drawings do not necessarily match.

In the following, the XYZ coordinate system will be referred to as appropriate. In addition, in this specification, when expressing a direction, if a positive or negative direction is to be distinguished, it is described with a positive or negative sign, such as "+X direction" and "-X direction". In addition, when a direction is to be expressed without distinguishing between positive and negative directions, it is simply described as "X direction". In other words, in this specification, when it is simply described as "X direction", both "+X direction" and "-X direction" are included. The same applies to the Y direction and Z direction. In this embodiment, the horizontal plane is parallel to the XY plane, and the vertical direction is the -Z direction. The main surfaces of the plate and the substrate that constitutes the plate, which will be described later, are shown to be parallel to the XY plane.

First Embodiment
A first embodiment of a microfluidic device will be described. Fig. 1 is a perspective view of a microfluidic device 100. The microfluidic device 100 has a plate 1 for culturing cells or tissues and analyzing the cultured product, and a holder 5 for supporting the plate 1 from below. The holder 5 has a shape that surrounds the side surface of the plate 1 on the XY plane. The plate 1 can be fitted into the inside of the holder 5 from the upper side (+Z side) of the holder 5.

[plate]
Plate 1 will be described. Fig. 2 is a top view of plate 1. Plate 1 has an opening 21 for injecting a fluid containing cells or tissues, and a groove 24 for culturing and analyzing cells or tissues. Fig. 3 is a side view of plate 1, and shows diagrammatically that plate 1 is formed by bonding a first substrate 2 and a second substrate 3.

3, the first substrate 2 has a first main surface 2a, a second main surface 2b opposite to the first main surface 2a, and a first side surface 2c connecting the first main surface 2a and the second main surface 2b. The second substrate 3 has two main surfaces and a second side surface 3c connecting the two main surfaces. The first substrate 2 is bonded so that the second main surface 2b is in contact with one of the main surfaces of the second substrate 3. The bonding is performed, for example, by irradiating the bonding surfaces of the first substrate 2 and the second substrate 3 with 172 nm ultraviolet light to activate the bonding surfaces and bond them together. In this embodiment, the thickness (dimension in the Z direction) of the second substrate 3 is thinner than the thickness (dimension in the Z direction) of the first substrate 2.

As shown in FIG. 2, in this embodiment, the second substrate 3 is smaller than the first substrate 2 when viewed in the Z direction. As a result, when the second substrate 3 is joined to the first substrate 2, even if the two substrates are joined slightly out of position, the second substrate 3 is less likely to protrude outward from the first side surface 2c of the first substrate 2. The first substrate 2 and the second substrate 3 are generally rectangular plate-shaped. Of the corners (28, 29) visible when the first substrate 2 is viewed from the first main surface 2a side, the two corners 28 located in the -X direction have a chamfered shape, and the two corners 29 located in the +X direction do not have a chamfered shape. By providing a chamfered shape only to the corners 28 located in the -X direction, the plate 1 can be fitted without making a mistake in the orientation of the plate 1 relative to the holder 5.

Figure 4 is a cross-sectional view taken along line A1-A1 in Figure 2. The first substrate 2 has a groove 24 formed on the second main surface 2b, and an opening 21 formed on the first main surface 2a. A chamfered shape 22 is provided near the entrance of the opening 21 to the first substrate 2 to prevent leakage of the fluid when the fluid is injected. The opening 21 is connected to the groove 24.

The second substrate 3 is bonded to the second main surface 2b of the first substrate 2 so as to cover the groove 24 connected to the two openings 21. The groove 24 functions as a hollow flow channel sandwiched between the two substrates (2, 3) by bonding the main surfaces of the first substrate 2 and the second substrate 3 to each other. This hollow flow channel is a microchannel (minute flow channel) having a width and depth on the order of micrometers to millimeters. A minute volume of fluid can be injected into the microchannel from the two connected openings 21, and fluid can be discharged from the microchannel through the openings 21. When there is fluid in the microchannel, the fluid is not necessarily in a state in which the fluid forms a flow. For example, the microchannel may be in a state in which there is no fluid flow, such as a state in which a fluid containing cells is stored in order to culture cells or tissues.

Examples of materials constituting the first substrate 2 or the second substrate 3 include resin materials such as polymethyl methacrylate (PMMA), polycarbonate (PC), cycloolefin copolymer (COC), cycloolefin polymer (COP), polystyrene (PS), and silicone. In this embodiment, COP, which has high heat resistance and transparency and produces little autofluorescence during fluorescence detection, is used for the first substrate 2 and the second substrate 3. Note that the first substrate 2 and the second substrate 3 may be made of a material that combines two or more of the above-mentioned resin materials. Also, the materials used for the first substrate 2 and the second substrate 3 may be different.

Referring to FIG. 2, recesses (25, 27) are provided on the first side surface 2c of the first substrate 2. As will be described in detail later, the protrusions of the holder 5 are fitted into the recesses (25, 27), and the tips of the protrusions come into contact with the recesses (25, 27).

[Holding body]
The holder in this embodiment will be described. Fig. 5 is a top view of the holder 5. As shown in Fig. 5, the holder 5 has a frame shape with a central region 4 penetrating therethrough. Since the central region 4 of the holder 5 is penetrating therethrough, it is possible to irradiate light from the upper side (+Z side) of the microfluidic device 100 and analyze the light that has passed through the groove 24 of the plate 1 on the lower side (-Z side) of the microfluidic device 100. It is also possible to irradiate light from the lower side of the microfluidic device 100 and analyze the light that has been reflected or scattered inside the groove 24 of the plate 1 on the lower side of the microfluidic device 100.

The holder 5 may have a shape in which the central region 4 of the holder 5 is not penetrated, i.e., may have a bottomed shape. If the holder 5 has a bottomed shape and is difficult to transmit light, it is advisable to irradiate light from above the microfluidic device 100 and receive the light reflected or scattered inside the groove 24 of the plate 1 at the top of the holder 5 for analysis.

In FIG. 5, the intersection R1 between the extension line of the outer wall surface 18 of the holder 5 extending in the Y direction and the extension line of the outer wall surface 19 extending in the X direction is the positioning reference when placing the holder 5 on the dispensing device. The holder 5 (i.e., the microfluidic device 100) with the plate 1 fitted in is placed in a positioned state on the table (not shown) of the dispensing device. The positioning of the holder 5 with respect to the table of the dispensing device may be performed, for example, based on the position of the intersection R1 and the extension direction of the outer surfaces (18, 19).

Figure 6 is a cross-sectional view taken along line B1-B1 in Figure 5. With reference to Figures 5 and 6, the holder 5 has an inner wall surface 12 that faces the side surface of the plate 1, and a support surface 13 that supports the plate 1. The support surface 13 contacts the main surface of the second substrate that constitutes the plate 1.

The material of the holder 5 may be, for example, a resin material such as polymethyl methacrylate (PMMA), polycarbonate (PC), cycloolefin copolymer (COC), cycloolefin polymer (COP), polystyrene (PS), silicone, or a metal material. In this embodiment, PS is used for the holder 5.

[Positioning element]
In order to position the plate 1 relative to the holder 5, the microfluidic device 100 has a positioning element. In this embodiment, the positioning element has protrusions (15, 17) that protrude toward the central region 4 from a partial region of the inner wall surface 12 (see FIGS. 1 and 5). The protrusions 15 protrude in the +X direction from a partial region of the inner wall surface 12 extending in the Y direction of the holder 5. The protrusions 17 protrude in the -Y direction from a partial region of the inner wall surface 12 extending in the X direction of the holder 5. In this specification, the protrusions (15, 17) are not part of the inner wall surface 12, but are treated as separate from the inner wall surface 12. The same applies to the case where the protrusions protrude from the first side surface 2c of the first substrate 2 in a modified example described later.

The positioning function of the protrusion 15 will be described. FIG. 7 is a top view of an enlarged A2 region (the region surrounding the protrusion 15) in FIG. 1. FIG. 8A is a cross-sectional view taken along the line C1-C1 in FIG. 7, which corresponds to the region in which the protrusion 15 is formed. Referring to FIG. 7, the protrusion 15 is inserted into a recess 25 formed in the first side surface 2c of the first substrate 2. The inserted protrusion 15 contacts the side surface 25a in the recess 25. As shown in FIG. 8A, the inserted protrusion 15 does not contact the second side surface 3c of the second substrate 3. When the plate 1 is fitted into the holder 5, the plate 1 is pressed against the holder 5 in the -X direction so that the side surface 25a of the first substrate 2 contacts the protrusion 15, and the protrusion 15 of the holder 5 functions as a positioning element for positioning the first substrate 2 with high precision in the X direction. In addition, as shown in FIG. 7, the protrusion 15 is inserted into the recess 25 with some play in the Y direction, which also has the effect of roughly positioning the first substrate 2 relative to the holder 5 in the Y direction. Note that, as shown in FIG. 8A, the protrusion 15 in this embodiment is in contact with the support surface 13, but the protrusion does not have to be in contact with the support surface 13 (it may be floating above the support surface 13).

Figure 8B is a cross-sectional view taken along line C2-C2 in Figure 7, and corresponds to the region where the protrusion 15 is not formed. As can be seen in Figure 8B, in the portion where the protrusion 15 is not formed, the inner wall surface 12 does not contact both the second side surface 3c of the second substrate 3 and the first side surface 2c of the first substrate. First, since there is no contact with the second side surface 3c of the second substrate 3, the second side surface 3c of the second substrate 3 is not used for positioning the plate 1. In addition, since the contact area between the first substrate 2 and the holder 5 is limited to the region of the protrusion 15, rather than the entire first side surface 2c of the first substrate 2, even if the first side surface 2c of the first substrate 2, excluding the protrusion 15, has localized bending or abnormal unevenness, it is unlikely to affect the positioning of the plate 1 including the first substrate 2 relative to the holder 5.

Like protrusion 15, protrusion 17 also functions as a positioning element for positioning first substrate 2 with high precision in the Y direction. Therefore, by pressing protrusions 15, 17 against first side surface 2c of first substrate 2, first substrate 2 can be positioned with high precision relative to holder 5 in the X and Y directions. And, as described above, because holder 5 can be positioned with high precision relative to the table of the dispensing device, by using the positioning element, first substrate 2 can be positioned with high precision relative to the table of the dispensing device.

Therefore, when the microfluidic device 100 of this embodiment is placed on the table of a dispensing device, the pipette tip of the dispensing device can be positioned with high precision relative to the opening 21 provided in the first substrate 2. Furthermore, when the microfluidic device 100 is used for analysis, the position of the groove 24 (microchannel), which is the analysis location, can be positioned with high precision relative to the analysis device.

In this embodiment, the holder 5 has two protrusions 15 protruding in the +X direction from the inner wall surface 12 extending in the Y direction, and two protrusions 17 protruding in the -Y direction from the inner wall surface 12 extending in the X direction, for a total of four (see FIG. 5). However, for precise positioning of the first substrate 2 in the X and Y directions, it is preferable to have at least three protrusions (15, 17). The at least three protrusions (15, 17) may include at least two protrusions protruding in a second direction (e.g., Y direction) perpendicular to the first direction from the inner wall surface 12 of the holder 5 extending in the first direction (e.g., X direction) or the first side surface 2c of the first substrate 2, and at least one protrusion protruding in the first direction from the inner wall surface 12 of the holder 5 extending in the second direction or the first side surface 2c of the first substrate 2.

The further away the protrusions (15, 17) are formed from the reference R1, the more accurately the first substrate 2 can be positioned. The distance between the protrusion 17 closest to the reference R1 and the reference R1 should be at least 1/3 of the length of the plate 1 in the X direction. Similarly, the distance between the protrusion 15 closest to the reference R1 and the reference R1 should be at least 1/3 of the length of the plate 1 in the Y direction. When there is only one protrusion 15, the distance between the protrusion 15 and the reference R1 should be at least 1/2 of the length of the plate 1 in the Y direction.

When multiple protrusions (15, 17) are provided on a single inner wall surface 12 extending in one direction, the greater the distance between the protrusions (15, 17), the more accurate and stable the positioning can be. For example, when a single inner wall surface 12 extending in the X direction has two protrusions 17 protruding in the -Y direction, it is preferable that the distance between these two protrusions 17 is at least 1/2 the length of the plate 1 in the X direction. Similarly, when a single inner wall surface 12 extending in the Y direction has two protrusions 15 protruding in the +X direction, it is preferable that the distance between these two protrusions 15 is at least 1/2 the length of the plate 1 in the Y direction.

The protrusions (15, 17) may be made of the same material as the material constituting the base of the protrusion. In other words, if they protrude from the holder, they may be made of the same material as the holder, and if they protrude from the first substrate, they may be made of the same material as the first substrate. By making them of the same material, advantages such as integral molding are obtained. The protrusions may be made of a material different from the material constituting the base of the protrusion. The material, shape, or dimensions of the protrusions (15, 17) may be selected so that they are more rigid than the holder 5 or the first substrate 2.

[Modifications of the plate]
FIG. 9 shows a modified plate. In the plate 30 of this modified example, the second substrate 31 is larger than the first substrate 2. In this modified example, even if the second substrate 31 becomes larger, it is necessary to prevent the second substrate 31 from contacting the protruding portion (15, 17) of the holder 5. Therefore, the shapes of both substrates are designed so that the first substrate 2 is located outside the second substrate 31 near the recessed portion (25, 27) of the plate 1 with which the protruding portion (15, 17) of the holder 5 contacts. Specifically, the recessed portion (25, 27) of the second substrate 31 is formed larger than the recessed portion (25, 27) of the first substrate. This allows the protruding portion (15, 17) of the holder 5 to contact the first substrate 2 without contacting the second substrate 31.

[First variant of the positioning element]
A first modified example of the positioning element is shown with reference to Fig. 10. Fig. 10 is a top view of the peripheral area of the positioning element in the X direction. In the first modified example, the first substrate 2 has a protrusion 61 as a positioning element on the first side surface 2c of the first substrate 2. The protrusion 61 contacts an inner wall surface 51a in the recess 51 of the holder 5. This allows the first substrate 2 to be positioned relative to the holder 5 in the X direction.

[Second variant of positioning element]
A second modified example of the positioning element is shown with reference to Fig. 11. Fig. 11 is a top view of the periphery of the positioning element in the X direction. In the second modified example, the protrusion 15 of the holder 5, which is the positioning element, is in contact with the flat first side surface 2c of the first substrate 2 without being inserted into the recess of the first substrate 2. Even if the protrusion 15 is not inserted into the recess of the first substrate 2, the first substrate 2 can be positioned in the X direction relative to the holder 5.

[Third variant of the positioning element]
A third modified example of the positioning element is shown with reference to Fig. 12. Fig. 12 is a top view of the periphery of the positioning element in the X direction. In the third modified example, the first substrate 2 has a protrusion 61 as a positioning element on the first side surface 2c. The protrusion 61 contacts the flat inner wall surface 12 of the holder 5. This allows the first substrate 2 to be positioned relative to the holder 5 in the X direction.

[Fourth modified example of positioning element]
A fourth modified example of the positioning element is shown with reference to FIG. 13. FIG. 13 is a top view of the positioning element in the X direction. FIG. 14 is a cross-sectional view taken along the line C3-C3 in FIG. 13. As shown in FIG. 13, in the fourth modified example, the holder 5 has a protrusion 16 that protrudes in the +X direction from the inner wall surface 12 extending in the Y direction. As shown in FIG. 14, the protrusion 16 has a contact surface 16a on the lower side (-Z side) that contacts the first substrate 2. The contact surface 16a contacts the outer peripheral edge (the outer region of the region where the opening is formed) of the first main surface 2a of the first substrate 2 and presses the first main surface 2a in the -Z direction. Friction occurs between the contact surface 16a and the outer peripheral edge of the first main surface 2a, restricting the movement of the first substrate 2 in the XY direction. In other words, the first substrate 2 is positioned in the XY direction by the protrusion 16 that contacts it above.

[Fifth variant of positioning element]
A fifth modified example of the positioning element is shown with reference to FIG. 15. FIG. 15 is a top view of the positioning element in the X direction. FIG. 16 is a cross-sectional view taken along the line C4-C4 in FIG. 15. In the fifth modified example, the lower contact surface 16a of the protruding portion 16 of the holder 5 presses the bottom surface 2e of the recess (located in the -Z direction) lower than the first main surface 2a of the first substrate 2 in the -Z direction at the outer periphery of the first main surface 2a of the first substrate 2. The friction generated between the contact surface 16a and the bottom surface 2e restricts the movement of the first substrate 2 in the X direction and the Y direction. Furthermore, the protruding portion 16 comes into contact with the wall 2f formed between the first main surface 2a and the recess, so that the first substrate 2 is positioned in the X direction by contact with the wall 2f. Thus, the first substrate 2 is positioned by friction caused by contact with the bottom surface 2e and by contact with the wall 2f.

[Sixth variant of the positioning element]
A sixth modified example of the positioning element is shown with reference to FIG. 17. In this modified example, a columnar protrusion 14 protrudes upward (+Z direction) from the support surface 13 of the holder 5. A recess 26 is provided on the second main surface 2b of the first substrate 2. In this modified example, when the plate 1 is fitted into the holder 5, the plate 1 is arranged so that the protrusion 14 is fitted into the recess 26 of the first substrate 2. When the protrusion 14 is inserted into the recess 26, the first substrate 2 is positioned in the XY direction. Note that a protrusion protruding downward (-Z direction) may be provided on the second main surface 2b of the first substrate 2, and a recess into which the protrusion is inserted may be provided on the support surface 13 of the holder 5.

The first to sixth modified examples have been described above. The modified examples may be applied to all positioning elements, or to some of the positioning elements. Also, different modified examples may be applied to each positioning element. For example, of the protrusions arranged side by side in the X direction, some of the protrusions may protrude from the surface of the first substrate 2 toward the surface of the holder 5, and the remaining protrusions may protrude from the surface of the holder 5 toward the surface of the first substrate 2.

Second Embodiment
A second embodiment of the microfluidic device will be described with reference to Figures 18 and 19. Matters other than those described below can be implemented in the same manner as in the first embodiment. Various modified examples shown in the first embodiment can also be applied to the second embodiment unless otherwise specified. The same applies to the third embodiment.

Figure 18 is a top view of the microfluidic device 200. The microfluidic device 200 has elastic bodies (45, 47) at positions facing the protrusions (15, 17) across the plate 1.

Figure 19 is a cross-sectional view taken along line B2-B2 in Figure 18. The action of the elastic body 45 will be described with reference to Figure 19. In this embodiment, the elastic body 45 is fixed in contact with the inner wall surface 12 of the holder 5. The elastic body 45 is designed to be more flexible than the protrusion 15, and the distance in the X direction between the elastic body 45 and the protrusion 15 facing the elastic body 45 when the plate 1 is not fitted into the holder 5 is designed to be slightly smaller than the dimension of the first substrate 2 in the X direction. As a result, when the plate 1 including the first substrate 2 is fitted into the holder 5, the elastic body 45 bends and applies a pressing force to the first substrate 2 as a reaction force. Then, the first substrate 2 (or the protrusion of the first substrate 2) that receives the reaction force tries to come into closer contact with the holder 5 (or the protrusion of the holder 5), improving the positioning accuracy of the first substrate 2 (plate 1) relative to the holder 5.

The elastic body 45 is made of a material that is less rigid than the protrusion 15, which is the positioning element. Typically, the elastic body 45 is made of a resin that is more flexible than the protrusion 15. The elastic body 45 may be made of an elastic material such as a leaf spring, in addition to resin.

However, the elastic body 45 may be made of the same material as the protrusion 15. When made of the same material as the protrusion 15, advantages such as the ability to mold the elastic body 45 integrally with the protrusion 15 and the retainer 5 are obtained. When using the same material for the elastic body 45 as the protrusion 15, it is advisable to make the elastic body 45 less rigid than the protrusion 15 by making the dimensions and shape of the elastic body 45 different from those of the protrusion 15, for example by designing the elastic body 45 to be thinner than the protrusion 15.

The elastic body 45 in this embodiment has an inclined surface 45a whose length in the Y direction becomes shorter as it advances in the +Z direction. This makes it easier to fit the plate 1 into the holder 5 from the +Z direction to the -Z direction. Also, in this embodiment, the elastic bodies 45 are the same in number as the protrusions 15 and are arranged at the same positions in the Y direction, but the elastic bodies 45 may be a different number than the protrusions 15 and may be arranged at different positions in the Y direction.

The above describes elastic body 45, which exerts a pressing force in the -X direction, but the above also applies to elastic body 47.

Third Embodiment
A third embodiment of the microfluidic device will be described with reference to Figures 20 to 23B. Figure 20 is a perspective view of a microfluidic device 300. Figure 21 is a perspective view of an upper frame, which will be described later. Figure 22A is a cross-sectional view taken along line B3-B3 in Figure 20. Figure 22B is a schematic diagram showing how the microfluidic device shown in the cross-sectional view of Figure 22A is assembled. Figure 23A is a cross-sectional view taken along line B4-B4 in Figure 20. Figure 23B is a schematic diagram showing how the microfluidic device shown in the cross-sectional view of Figure 23A is assembled.

The microfluidic device 300 has an upper frame 50. The upper frame 50 has a frame shape with a central region 4 penetrating therethrough (see FIG. 21). After the plate 1 is fitted into the holder 5, the upper frame 50 is fitted inside the holder 5 (see FIGS. 22B and 23B). The frame bottom 55 of the fitted upper frame 50 covers the outer periphery of the first main surface 2a of the first substrate 2 (the outer region of the region where the opening 21 is formed) (see FIGS. 22A and 23A). The upper frame 50 is designed to have a size and shape that does not cover the region where the opening 21 is formed. This allows fluid to be injected into the opening 21 with the upper frame 50 fitted into the holder 5.

As shown in FIG. 22B, in the vicinity of line B3-B3 in FIG. 20, the holder 5 has a protrusion 15. The first side surface 2c of the first substrate 2 contacts the protrusion 15, and the first substrate 2 is positioned in the X direction. In the vicinity of line B3-B3, the upper frame 50 is merely stacked on the outer peripheral edge of the first main surface 2a and the protrusion 15, and does not function as a positioning element in the X direction.

As shown in FIG. 23B, in the vicinity of line B4-B4 in FIG. 20, the holder 5 does not have a protrusion 15. On the other hand, the upper frame 50 has a second protrusion 53 which is a part of the frame bottom 55 that protrudes. When the upper frame 50 is fitted, the second protrusion 53 comes into contact with the first side surface 2c of the first substrate 2, and the first substrate 2 is positioned in the X direction. In other words, in the vicinity of line B4-B4, the upper frame 50 functions as a positioning element in the X direction.

As described above, the positioning elements in this embodiment are provided on both the holder 5 and the upper frame 50. This allows the first substrate 2 to be positioned with high precision relative to the holder 5. Before the upper frame 50 is fitted, loose positioning is acceptable, leaving some play between the first substrate 2 and the holder 5, making it easy to fit the plate 1 into the holder 5. Then, by fitting the upper frame 50 into the holder 5, the number of positioning elements increases, and the first substrate 2 can be positioned with high precision relative to the holder 5. This allows both ease of fitting and high precision positioning of the first substrate 2.

The upper frame 50 has a plurality of liquid storage tanks 56 surrounded by a frame bottom 55, an inner frame 57, an outer frame 58, and a partition plate 59 (see Figs. 21, 22A, and 23A). The liquid storage tank 56 is a container configured to store liquid. A plurality of liquid storage tanks 56 are arranged to surround the central region 4 of the plate 1. The purpose of the liquid storage tanks 56 is to suppress changes in the concentration of the liquid injected into the plate 1. Since the amount of liquid injected into the plate 1 is small, the components of the injected liquid may evaporate over time. If a portion of the liquid components evaporates, the concentration of the liquid remaining in the groove 24 changes, which is not preferable for cell culture or analysis. Therefore, a liquid (e.g., water) for controlling the humidity of the atmosphere of the plate 1 is injected into the liquid storage tank 56 and the liquid is stored. This prevents a decrease in the humidity of the atmosphere of the plate 1 and prevents the liquid injected into the plate 1 from evaporating.

The first, second and third embodiments have been described above. However, the present invention is not limited to the above-described embodiments, and the above-described embodiments can be combined or various modifications or improvements can be made to each embodiment without departing from the spirit of the present invention.

In the above description, the positioning of the plate 1 in both the X and Y directions has been considered, but when positioning the plate 1 relative to the holder 5 in only one of the X and Y directions, a highly accurate positioning effect can be obtained, although only in that one direction. One or more positioning elements are sufficient for positioning in one direction.

In the above, plate 1 is composed of two substrates, first substrate 2 and second substrate 3, but plate 1 may be composed of three or more substrates. When composed of three or more substrates, a protrusion that brings the first substrate into contact with the holder is provided in a partial area of at least one of first substrate 2 and holder 5 having an opening. This protrusion that brings the first substrate into contact with the holder is not in contact with any substrate other than the first substrate having an opening, or is not provided on any substrate other than the first substrate having an opening.

Cell and tissue culture and analysis have been described above as applications of the microfluidic device. However, the microfluidic device according to the present invention can be used for applications other than cell and tissue culture and analysis. For example, the microfluidic device according to the present invention can also be used for mixing, separation, reaction, synthesis, extraction, or analysis of chemicals.

1, 30: Plate 2, 42: First substrate 2a: First main surface 2b (of first substrate): Second main surface 2c (of first substrate): First side surface 2e (of first substrate): Recess 2f (of first substrate): Wall 3, 31 (of first substrate): Second substrate 3c: Side surface 4 (of second substrate): Central region 5: Holder 12: Inner wall surface 13 (of holder): Support surface 14, 15, 16, 17, 61 (of holder): Protrusion 16a: Contact surface 18, 19 (of protrusion): Outer wall surface 21 (of holder): Opening 22 (of first substrate): Chamfered shape 24 (of opening): Groove 25, 26: Recess 25a: Side surface 28, 29 (inside recess): Corner 45, 47: Elastic body 50: Upper frame 51: Recess 52 (of holder): Outer peripheral surface 53 (of upper frame) : Second protruding portion 55 : Frame bottom 56 : Liquid storage tank 57 : Inner frame 58 : Outer frame 59 : Partition plate 100, 200, 300 : Microfluidic device

Claims (8)

a plate having a first substrate having a first main surface in which an opening for injecting a fluid is formed, a second main surface opposite to the first main surface, and a first side surface connecting the first main surface and the second main surface, and a second substrate bonded to the second main surface;
a holder having an inner wall surface surrounding the outer surface of the plate while being spaced apart from the outer surface of the plate, and a lower surface on which the second substrate of the plate is placed;
a protrusion formed on a partial region of a surface of at least one of the first substrate and the holder, protruding from the surface in a direction in which the first substrate and the holder face each other, thereby bringing the first substrate and the holder into contact with each other. The microfluidic device according to claim 1, characterized in that the recess into which the protrusion is fitted is formed in a partial area of the surface of at least one of the first substrate and the holder. The microfluidic device according to claim 1 or 2, characterized in that the protrusion protrudes from at least one of the first side surface and the inner wall surface. The microfluidic device according to claim 3, characterized in that the protrusions include at least two protrusions protruding from the inner wall surface or the first side surface extending in a first direction in a second direction perpendicular to the first direction, and at least one protrusion protruding in the first direction from the inner wall surface or the first side surface extending in the second direction. The holder includes an elastic body that contacts a partial area of the first side surface,
The microfluidic device according to any one of claims 1 to 4, characterized in that the first side surface in contact with the elastic body is located opposite the protrusion with the second substrate in between. an upper frame that is fitted inside the holder, exposes the opening formed in the first main surface of the first substrate, and covers an outside of a region of the first main surface where the opening is formed;
The microfluidic device according to any one of claims 1 to 5, characterized in that a portion of the bottom of the upper frame has a second protrusion that protrudes from the bottom of the frame and contacts the first side of the first substrate. The microfluidic device according to claim 6, characterized in that the upper frame is provided with a liquid storage tank. The microfluidic device according to any one of claims 1 to 7, which is used for cell or tissue culture.

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