Provided is a micro-fluid chip that enables reducing contamination between branch channels, has a relatively simple channel structure and facilitates miniaturization. A micro-fluid chip (1) having a channel structure (3) through which a fluid is delivered, wherein the channel structure (3) includes: a main channel (4) having an inflow port (5) and an outflow port (6); a plurality of branch channels (11) to (13) connected to the main channel (4), each branch channel having an inflow end on a side connected to the main channel (4) and an outflow end that is an end portion on an opposite side to the inflow end; and a sub-branch channel (14) connected to the main channel (4) between at least one pair of adjacent branch channels (11) and (12) among the plurality of branch channels (11) to (13), the sub-branch channel (14) having an inflow end on a side connected to the main channel (4).

TECHNICAL FIELD

The present invention relates to a micro-fluid chip having a channel structure through which a fluid is delivered.

BACKGROUND ART

Conventionally, various micro-fluid chips have been known. For example, in a micro reactor for genetic testing described in Patent Literature 1 below, a plurality of reaction chambers are provided for a plurality of branch channels branched from a main channel, respectively. Here, in order to prevent contamination, a reagent delivering component and a control/detection component are independently formed for each specimen. With the use of check valves on the upstream side and the downstream side of each reaction chamber, contamination between the reaction chambers is prevented.

Patent Literature 2 below discloses the use of a gas generation valve in order to prevent movement of fluid.

CITATION LIST

Patent Literature

SUMMARY OF INVENTION

Technical Problem

As described in Patent Literature 1 and Patent Literature 2, in a micro-fluid chip having a plurality of reaction chambers, a check valve or a gas generator valve has to be used for each reaction chamber in order to prevent contamination between the reaction chambers. Hence, there have been problems such as an increase in the number of valves for controlling such liquid delivery, and complicated structure. It has also been difficult to miniaturize micro-fluid chips.

It is an object of the present invention to provide a micro-fluid chip capable of reducing the number of valves for fluid delivery control, simplifying the channel structure, and effectively achieving further miniaturization.

Solution to Problem

A micro-fluid chip according to the present invention is a micro-fluid chip having a channel structure through which a fluid is delivered, wherein the channel structure includes: a main channel having an inflow port through which the fluid enters and an outflow port through which the fluid flows out; a plurality of branch channels connected to the main channel, each of the branch channels having an inflow end on a side connected to the main channel and an outflow end that is an end portion on an opposite side to the inflow end; and a sub-branch channel connected to the main channel between at least one pair of adjacent branch channels among the plurality of branch channels, the sub-branch channel having an inflow end on a side connected to the main channel. In the micro-fluid chip according to the present invention, preferably, the sub-branch channel has no outflow end.

In the micro-fluid chip according to the present invention, preferably, the inflow end of the sub-branch channel is open to an inner wall surface of the main channel shared by the inflow ends of two or more of the branch channels. In this case, contamination between the branch channels can be more effectively prevented.

In another specific aspect of the micro-fluid chip according to the present invention, an inner wall where the branch channels and the sub-branch channel are open is an inner wall positioned in a direction orthogonal to a direction in which the branch channels extend. In a further specific aspect of the micro-fluid chip according to the present invention, a transverse cross section of the main channel is rectangular.

In other specific aspect of the micro-fluid chip according to the present invention, the sub-branch channel is provided at all positions between adjacent branch channels. In this case, it is possible to more effectively prevent contamination between all of adjacent branch channels.

In still another specific aspect of the micro-fluid chip according to the present invention, the sub-branch channel has a portion with a channel cross-sectional area larger than a channel cross-sectional area at the inflow end of the sub-branch channel connected to the main channel. In this case, the fluid can be reliably guided into the sub-branch channel. The fluid guided into the sub-branch channel is unlikely to leak out of the sub-branch channel. Therefore, contamination can be more reliably prevented.

In yet another specific aspect of the micro-fluid chip according to the present invention, the micro-fluid chip further includes a connection channel connected to the outflow end side of the plurality of branch channels, wherein the connection channel is connected to the main channel.

In other specific aspect of the micro-fluid chip according to the present invention, the inflow end and the outflow end of the main channel are provided with a seal part capable of stopping the fluid from moving.

Advantageous Effects of Invention

In the micro-fluid chip according to the present invention, since a valve or the like for fluid delivery control does not need to be provided for each of the branch channels, it is possible to reduce the number of valves or the like and simplify the channel structure. In addition, it is also possible to facilitate miniaturization of the micro-fluid chip.

DESCRIPTION OF EMBODIMENTS

Hereinafter, the present invention will be clarified by describing specific embodiments of the present invention with reference to the drawings.

FIG. 1is a schematic view showing a micro-fluid chip according to the first embodiment of the present invention, andFIG. 2is a schematic plan view showing the channel structure.

A micro-fluid chip1has a chip main body2in the form of rectangular plate. The chip main body2is composed of a laminate formed by superimposing a plurality of layers one upon another. Material that forms the plurality of layers is made of appropriate material such as synthetic resin and glass.

A channel structure3indicated by the broken line inFIG. 1is provided in the chip main body2. As shown inFIG. 2, the channel structure3is a portion through which a fluid is transported, and the channel structure3has a main channel4. An inflow port5is provided at one end of the main channel4, and an outflow port6is provided at the other end. A valve7is provided on the inflow port5side, and a valve8is provided on the outflow port6side.

A valve9is provided for the main channel4on a downstream side relative to a portion where a later-described branch channel13is connected. That is, the valve9is provided between the portion where the branch channel13is connected and the portion where the valve8is provided.

The valves7,8and9constitute a seal part that can seal the main channel4. However, instead of the valves7,8,9, it may also be possible to use other seal member that can open and close the main channel4by external manipulation.

One end of each of a plurality of branch channels11to13is connected to the main channel4. The branch channels11to13are provided as reaction chambers for PCR reaction. At end portions of the branch channels11to13on an opposite side to the side connected to the main channel4, channel resistance portions16to18having a smaller cross-sectional area than the branch channels11to13are provided. One end of each of the branch channels11to13is an inflow end and is open to the main channel4. The other ends of the branch channels11to13are outflow ends and are connected to the channel resistance portions16to18.

Downstream ends of the channel resistance portions16to18are connected to a connection channel19. The connection channel19is connected to the main channel4on the downstream side relative to the valve9.

Between adjacent branch channels11and12, a sub-branch channel14is connected to the main channel4. Also, between adjacent branch channels12and13, a sub-branch channel15is connected to the main channel4. Each of the sub-branch channels14,15has an inflow end connected to the main channel4, but the sub-branch channels14,15have no gas outflow port. The inflow ends of the sub-branch channels14,15are open to the main channel4.

The sub-branch channel14is provided to prevent specimen and reagent contamination between the branch channels11and12. The sub-branch channel15is also provided to prevent contamination between adjacent branch channels12and13.

In the micro-fluid chip1, a fluid that is a liquid specimen or liquid reagent is delivered. More specifically, the valves7,8,9are opened, and the fluid is delivered to the main channel4from the inflow port5. As shown inFIG. 3, the delivered fluid fills the inside of the branch channels11,12,13. In this case, the delivery of fluid is performed at a delivery pressure lower than the channel resistance of the channel resistance portions16to18. Therefore, the fluid is not delivered to the channel resistance portions16to18.

Further, a gas is introduced from the inflow port5side to cause the fluid in the main channel4to flow out from the outflow port6. Next, the valves7and9are closed. In this state, the fluid is not present in the main channel4. Only the inside of the branch channels11to13is filled with the fluid.

When the valve9is closed, the valve8may also be closed.

As described above, the fluid is sealed in the branch channels11,12and13.

In a PCR reaction, a step of heating a fluid in which RNA or the like is mixed with a reagent, to a predetermined temperature, is repeated. Thus, RNA or the like is subjected to polymerization, and an extended nucleic acid chain is detected using optical detection means or the like. In this case, the fluid as a reaction liquid is repeatedly heated in the branch channels11,12,13as described above. When the fluid is heated, the fluid expands and tries to move from the branch channels11to13side to the main channel4side. Hence, there is a risk of contamination between the fluid in the branch channel11and the fluid in the branch channel12.

However, in the micro-fluid chip1, the sub-branch channel14is provided between adjacent branch channels11and12. Therefore, even if there is the fluid that has expanded with heat and moved to the main channel4side, the fluid enters the sub-branch channel14, and does not reach the branch channel12and the branch channel11on the other side. Thus, contamination between the fluids is unlikely to occur between the adjacent branch channels11and12. Also, since the sub-branch channel15is provided between the adjacent branch channels12and13, contamination can be similarly prevented.

FIG. 4is a partially cutaway enlarged cross-sectional view corresponding to a portion along the A-A line inFIG. 2. This section is a transverse cross section of the main channel4. The main channel4has inner wall surfaces4ato4d. In the present invention, preferably, the inflow ends of the sub-branch channels14,15are open to the inner wall surface4ashared by the inflow ends of the plurality of branch channels11to13.

It is desirable that the sub-branch channels14,15be preferably connected to the same inner wall of the main channel4to which the branch channels11to13are connected. Although not particularly limited, the main channel4has a rectangular transverse cross-sectional shape in the present embodiment. Therefore, the main channel4has four inner walls4ato4d. The sub-branch channel14is connected to the inner wall4aamong the inner walls. As shown with the broken line, the branch channel11is also connected to the inner wall4a. In the case where the inflow ends of the branch channels11to13and the inflow ends of the sub-branch channels14,15are open to the same inner wall4ain this manner, the fluid that has expanded with heat and entered the main channel4from the branch channels11to13can easily enter the sub-branch channel14along the inner wall4a. It is therefore possible to more effectively prevent contamination. However, the inflow ends of the branch channels11to13and the inflow ends of the sub-branch channels14,15may be open to a different inner wall of the main channel4. In the present embodiment, the sub-branch channel14is extended from the inner wall4aof the main channel4in a direction away from the main channel4, that is, the direction in which the branch channel11and the branch channel12extend. However, it may also be possible to use a sub-branch channel14A shown with the dashed line inFIG. 4. The sub-branch channel14A is connected to the inner wall4aand is extended downward from the inner wall4aof the main channel4. In this case, the sub-branch channel14A is also open toward the inner wall surface4aof the main channel4shared by the inflow ends of the plurality of branch channels11to13.

Moreover, like the sub-branch channel14A, the direction in which the sub-branch channel extends is not limited to the direction in which the branch channels11to13extend, and may be a depth direction of the main channel4.

Further, in the present embodiment, the main channel4is linearly extended from a portion where the branch channel11is connected toward a portion where the branch channel3is connected. However, in the present invention, the main channel may have a curved portion between the branch channels. Accordingly, the inflow end of the sub-branch channel may be open in this curved portion.

Although not particularly limited, in the present embodiment, the inner wall4aof the main channel4is positioned in a direction orthogonal to the direction in which the branch channels11,12,13extend. Thus, it is possible to more effectively prevent contamination between the adjacent branch channels11and12and between the adjacent branch channels12and13.

In the micro-fluid chip1, the sub-branch channels14,15are provided between both of a pair of adjacent branch channels11and12and a pair of branch channels12and13. However, the sub-branch channels are not necessarily provided at all positions between a plurality of pairs of adjacent branch channels. The sub-branch channel needs to be provided between at least one pair of branch channels. It is desirable that the sub-branch channels14,15be preferably provided at all positions between a pair of adjacent branch channels as in the present embodiment.

The sub-branch channels14,15are preferably provided with portions having a larger channel cross-sectional area than the channel cross-sectional area at the inflow ends of the sub-branch channels14,15connected to the main channel4. Therefore, in the present embodiment, as shown inFIG. 2, a portion with the maximum channel cross-sectional area of the sub-branch channel is provided at a position different from the portion connected to the main channel4.

Thus, it is desirable that the sub-branch channels14,15be provided with portion(s) having the larger channel cross-sectional area than the channel cross-sectional area of the inflow ends. Consequently, the fluid that has entered due to heat expansion can be more reliably guided into the sub-branch channel14. In addition, the fluid guided into the sub-branch channel14is unlikely to leak out of the sub-branch channel4.

The portion with the larger channel cross-sectional area of the sub-branch channel can be formed by enlarging at least one of the dimension in the width direction and the dimension in the depth direction of the transverse cross section of the sub-branch channel.

In the micro-fluid chip1, the cross-sectional shape and size of the channel structure refer to a minute channel that produces micro effects when transporting a fluid. In such a channel structure, the fluid is strongly influenced by surface tension, and behaves differently from the fluid flowing through a regular large size channel.

The transverse cross-sectional shape and size of the channel through which the fluid is delivered are not particularly limited as long as the channel produces the above-described micro effects. Therefore, the transverse cross sections of the main channel4, the branch channels11,12,13and the sub-branch channels14,15may be rectangular, circular, ellipse, or the like. For example, in the case where a pump or gravity is used to cause the fluid to flow into the channel through which the fluid is to be delivered, if the transverse cross-sectional shape of the channel is approximately rectangular (including square) from the viewpoint of further reducing the flow resistance, the dimension of the shorter side is preferably not less than 20 μm, more preferably not less than 50 μm, and further preferably not less than 100 μm. Also, from the viewpoint of further miniaturizing the micro-fluid chip1, the dimension of the shorter side is preferably not more than 5 mm, more preferably not more than 1 mm, and further preferably not more than 500 μm.

If the transverse cross-sectional shape of the channel through which the fluid is delivered is approximately circular, the diameter (the short diameter in the case of an ellipse) is preferably not less than 20 μm, more preferably not less than 50 μm, and further preferably not less than 100 μm. From the viewpoint of further miniaturizing the micro-fluid chip1, the diameter (the short diameter in the case of an ellipse) is preferably not more than 5 mm, more preferably not more than 1 mm, and further preferably not more than 500 μm.

On the other hand, for example, when a capillary phenomenon is more effectively utilized to cause the fluid to flow into the channel through which the fluid is to be delivered, if the transverse cross-sectional shape of the channel is approximately rectangular (including square), the dimension of the shorter side is preferably not less than 5 μm, more preferably not less than 10 μm, and further preferably not less than 20 μm. Moreover, the dimension of the shorter side is preferably not more than 200 μm, and more preferably not more than 100 μm.

The contamination can be more prevented with an increase in the capacity of the sub-branch channels14,15. However, in order to reduce a decrease in the fluid in the sub-branch channels14,15due to condensation, the capacity of the sub-branch channel is desirably not more than 5 μL.

It is desirable that the channel cross-sectional area of the sub-branch channel on the inflow end side be about 0.01 mm2to 2.0 mm2. In this case, the fluid that has entered the main channel4side can be more reliably guided into the sub-branch channels14,15.

The distance between a portion of the branch channel11which is open in the main channel4and a portion of the branch channel12which is open in the main channel4, that is, the distance between the portions which are open in the main channel4between the adjacent branch channels11and12is desirably 10.0 mm or less. In this case, it is possible to miniaturize the micro-fluid chip1.

However, the distance from the inflow end of each of the branch channels11,12connected to the main channel4to the inflow end of the sub-branch channel14connected to the main channel4is preferably less than 5.0 mm. In this case, the fluid that has entered the main channel4due to heat expansion can be reliably guided into the sub-branch channel14.

The contact angle between the fluid and a wall surface of the channel structure3is preferably not less than 20° and not more than 120°. Within this range, the fluid can be reliably guided into the branch channels11to13as described above to perform the PCR reaction and the like, and contamination can be effectively prevented as described above.

The shapes and arrangement of the main channel and the sub-branch channel in the present invention are not particularly limited. Referring toFIG. 5toFIG. 10, channel structures in micro-fluid chips of the second to seventh embodiments will be described.

In the second embodiment shown inFIG. 5, a channel structure21is formed in substantially the same manner as the channel structure3shown inFIG. 2, except that sub-branch channels22,23which are rectangular in planar shape are used.

A channel structure24in the micro-fluid chip of the third embodiment shown inFIG. 6is formed in the same manner as the channel structure3, except that sub-branch channels25,26which are triangular in planar shape are provided. Furthermore, in a channel structure27of the micro-fluid chip of the fourth embodiment shown inFIG. 7, sub-branch channels28,29having a rectangular shape longer and thinner than the branch channels11to13are provided. Thus, as shown in the sub-branch channels22,23,25,26,28,29, the planar shapes of the sub-branch channels are not particularly limited.

A channel structure31of the micro-fluid chip of the fifth embodiment shown inFIG. 8is arranged so that the length of the sub-branch channel22>the length of the sub-branch channel23. Further, a channel structure32of the micro-fluid chip of the sixth embodiment shown inFIG. 9is arranged so that the length of the branch channel11>the length of the branch channel12>the length of the branch channel13, and the length of the sub-branch channel22>the length of the sub-branch channel23. As shown in the channel structures31,32, the lengths of the plurality of branch channels may be different from each other, and the lengths of the plurality of sub-branch channels may be different from each other.

Furthermore, as shown in a channel structure41of the micro-fluid chip of the seventh embodiment shown inFIG. 10, sub-branch channels42,43may be provided on the upstream side or the downstream side of the main channel4relative to the portion where the plurality of branch channels11,12are provided. That is, the sub-branch channel42or the sub-branch channel43may be provided at a portion other than the portion between the adjacent branch channels11and12.

InFIG. 2, the connection channel19is provided, but, as in a channel structure51of the eighth embodiment shown inFIG. 11, valves52to54may be provided on the downstream side of the first to third branch channels11to13without providing the connection channel19. That is, the fluid after the reaction may be discharged from another channel by opening the valves52to54, without returning the fluid to the main channel4.

As in the ninth embodiment shown inFIG. 12, the micro-fluid chip1may be used by arranging a plane including the plurality of branch channels11to13in a direction orthogonal to the vertical direction, that is, in the direction shown inFIG. 12. Alternatively, as shown inFIG. 13, the micro-fluid chip1may be used by arranging the plane including the plurality of branch channels11to13in the vertical direction.

The fluid in the micro-fluid chip according to the present invention is not limited to specimens and reaction liquids for use in the PCR reaction, and can be widely used with various analysis methods involving heating of fluid.

REFERENCE SIGNS LIST