JP2009236555A - Fluid device and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce air bubbles remaining in a flow passage or reaction container. <P>SOLUTION: A cover substrate 11 and a base substrate 13 are laminated to form flow passages 17 and 23 for allowing a liquid to flow and the reaction container 15 to the joined surfaces of both substrates. The material of the bonding surfaces of both substrates is selected so as to have a contact angle of 90° or above with respect to the joined surfaces of both substrates. Recessed and protrusions are formed between the flow passages 17 and 19, the reaction container 15 and the edge surface of a device to form gaps. The size of each of the gaps is set so as to pass air but not to pass the liquid. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to organic chemistry for synthesizing organic substances with a small amount of sample and biochemistry for performing PCR (polymerase chain reaction) method. The present invention relates to a fluid device such as a μTAS (Micro Total Analysis System) and a manufacturing method thereof.

  A micro multi-chamber apparatus is used as a small reaction apparatus used for biochemical analysis and normal chemical analysis. As such an apparatus, for example, a microwell reaction vessel plate such as a microtiter plate in which a plurality of wells as reaction vessels are formed on a flat substrate surface is used (see Patent Document 1).

Conventionally, as shown in FIG. 3, a microchip device for analyzing and reacting a small amount of a liquid sample has a cover substrate 11 on a base substrate 13 in which flow paths 17 and 19 for flowing a liquid and a reaction vessel 15 are formed. It is formed by bonding.
In such a device, a resin material is often used for the substrate. The resin material has a property that it is difficult to wet with respect to an aqueous sample as compared with a material such as glass.

JP-A-2005-177749

When a fluid device is made of the resin material as described above and an aqueous sample is used as a liquid sample, bubbles in the liquid sample remain in a part of the flow path or reaction container in the fluid device, and analysis or It may interfere with the reaction.
Accordingly, an object of the present invention is to provide a fluidic device capable of reducing bubbles remaining in a flow path, a reaction container, and the like, and a method for manufacturing the fluidic device.

  The fluidic device of the present invention is a fluidic device in which at least two members are bonded to each other and a flow path for flowing liquid is formed by both members. The material of the joint surface between both members is that the liquid flowing through the flow path is between both members. Is selected so as to have a contact angle of 90 ° or more with respect to the joint surface, and at least one of the joint surfaces between the two members is formed with irregularities so that a gap is formed between the two members, The size of the gap is such that the absolute value of the pressure due to capillary force is larger than the pressure in the flow path in contact with the liquid gap flowing through the flow path, so that the gas is allowed to pass and the liquid is not allowed to pass. It is characterized by communicating from the flow path to the outside of the fluid device.

  In order to adjust the flow of the liquid in the fluid device, the flow path may be provided with a valve for controlling the flow of the liquid. By closing the valve and supplying the liquid to the flow path, the pressure in the flow path is increased so that the bubbles in the liquid are discharged from the gap between the two members to the outside.

  The fine irregularities preferably have a height of 500 μm or less.

  In the fluid device manufacturing method of the present invention, at least two members including a base substrate and a cover substrate are bonded to each other to form a flow path for flowing a liquid, and unevenness is formed on at least one of the joint surfaces between the two members. As a result, a gap is formed between the two members. The base substrate is formed by resin molding using a mold in which the portion corresponding to the flow path is a convex portion and the portion corresponding to the bonding surface is a concave portion, and the bottom surface of the concave portion is formed with fine irregularities. By performing this process, a groove serving as a flow path is formed on the flat surface, and the flat surface is formed as a base substrate having fine irregularities.

  A preferred example for producing the mold is a method comprising the following steps (A) to (C). That is, (A) forming an etching resistant film on the surface of a silicon substrate, leaving the etching resistant film in a portion that becomes the flow path by photolithography and etching, and patterning to expose a portion that becomes a bonding surface (B) The silicon substrate having the etching-resistant film pattern is subjected to dry etching while alternately introducing an etching gas and an etching protective film forming gas, thereby forming a concave portion at a bonding surface, and A step of forming fine irregularities on the bottom surface of the recess, and (C) a step of removing the etching resistant film pattern thereafter.

  In the fluidic device of the present invention, the material of the joint surface between the two members bonded to form the flow path has a contact angle of 90 ° or more with respect to the joint surface between the two members. A gap is formed between the two members so that the gas does not pass and the liquid does not pass, and the gap extends from the flow path to the outside of the fluid device, so that it remains in the fluid device. Air bubbles can be easily removed to the outside.

  If a valve for controlling the flow of the liquid is provided in the flow path, the pressure of the liquid flowing through the flow path can be adjusted even when the sample discharge port of the fluid device is not blocked.

Examples of the present invention will be described below.
FIG. 1: has shown the schematic of the fluid device in one Example, (A) is a perspective view, (B) is a vertical sectional view in XX of (A).

  A cylindrical reaction vessel 15 having an opening having an inner diameter of 3 mm and a depth of 1.0 mm is formed on one surface of the base substrate 13. The inner diameter and depth of the reaction vessel 15 are not particularly limited. A liquid introduction flow path 17 and a liquid discharge flow path 19 connected to the reaction container 15 are formed in the base substrate 13. The width and depth of the liquid introduction channel 17 and the liquid discharge channel 19 are, for example, 1 mm or less.

  The material of the base substrate 13 including the reaction vessel 15 is not particularly limited as long as the contact angle of the liquid handled by the fluid device is 90 ° or more. However, when the fluid device is used as a disposable device, it is inexpensive. It is preferable that the material is available. As such a material, for example, a resin material such as polydimethylsiloxane (PDMS), polypropylene, and polycarbonate is preferable. When the substance in the reaction vessel 15 is detected by light such as absorbance, fluorescence, chemiluminescence, or bioluminescence, it is formed of a light transmissive resin so that optical detection can be performed from the bottom side. Preferably it is. In particular, when fluorescence detection is performed, the base substrate 13 is made of a material such as a resin having a low autofluorescence property (a property of generating less fluorescence from itself) and a light transmitting resin, such as polycarbonate. Is preferred. The thickness of the base substrate 13 is, for example, 2.0 to 4.0 mm. From the viewpoint of low autofluorescence for fluorescence detection, it is preferable that the thickness of the base substrate 13 in the reaction vessel 15 is thinner.

  On the base substrate 13, the cover substrate 11 is bonded so as to cover the reaction vessel 15, the fluid introduction channel 17 and the fluid discharge channel 19. The material of the cover substrate 11 is not particularly limited as long as the contact angle of the liquid handled by the fluid device is 90 ° or more, but is made of, for example, PDMS or silicone rubber. The thickness of the cover substrate 11 is, for example, 1.0 to 4.0 mm.

  The cover substrate 11 has a hole 21 serving as a fluid inlet and a hole 23 serving as a fluid outlet at positions corresponding to the ends of the flow channels 17 and 19. One end of the liquid introduction channel 17 is connected to a liquid introduction port 21 used for introducing the liquid, and the other end is connected to the reaction vessel 15. One end of the liquid discharge channel 19 is connected to a liquid discharge port 23 used for discharging the liquid, and the other end is connected to the reaction vessel 15 at a position different from the position where the other end of the liquid introduction channel 17 is connected. It is connected.

  A liquid feeding device such as a syringe pump is connected to the liquid inlet 21 to feed a liquid sample, and a drain is connected to the liquid outlet 23 from which the liquid sample is discharged to discharge the liquid sample. In the case of the embodiment shown in FIG. 1, the liquid inlet 21 and the liquid outlet 23 are formed as through holes in the cover substrate 11, but may be formed in the base substrate 13.

  Fine irregularities 25 are formed on the bonding surfaces of the substrates 11 and 13. The fine irregularities 25 are formed from positions adjacent to the reaction vessel 15, the flow path 17, and the flow path 19 to the outer periphery of the substrate 13, and are connected to the outside. By forming the fine irregularities 25 continuously on the joint surfaces of the substrates 11 and 13, gaps are continuously generated between the flow path through which the liquid sample flows and the outer periphery of the fluid device. The size of the voids is preferably 500 μm or less, but the size of each of the fine irregularities 25 may be 10 nm to 1000 nm and the height may be 10 nm to 1000 nm. In addition, since the contact angle of the liquid sample flowing through the flow channel with respect to the bonding surface of the substrates 11 and 13 is 90 ° or more, only gas passes through the gaps due to the fine irregularities 25 and liquid does not pass.

Next, the manufacturing method of the fluid device of the present invention will be described.
FIG. 2 is a flowchart for explaining the manufacturing process of the fluid device in one embodiment.
(A) A chromium film 29 as an etching resistant film is formed on one surface of the silicon substrate 27a, and the reaction vessel 15, the flow path 17, and the flow path 19 (see FIG. 1) are formed by photolithography and etching. Covering and patterning are performed so as to expose a portion (bottom surface 31) which becomes a bonding surface of the substrate. The etching resistant film is not limited to the chromium film, and a silicon oxide film may be used.

(B) Dry etching is performed using the chromium film 29 as an etching mask. As a dry etching method at this time, for example, a Bosch process using ICP-RIE (inductive plasma-reactive ion etching) is used. In this method, an etching gas and an etching protective film forming gas are alternately introduced, and the etching process and the etching protective film forming process are alternately performed. At this time, the fine unevenness 33a can be formed on the bottom surface 31 of the concave portion formed by etching by adjusting the balance between the etching step and the etching protective film forming step slightly to the excessive protective film formation.

  As another example of the method for forming the fine irregularities 33a, when a metal mask such as chrome is used as an etching mask, sputtering occurs on the mask surface during the etching, and the sputtered metal atoms are formed by etching. Adhering to the bottom surface 31 causes a phenomenon called a micromask. With this micromask, fine irregularities 33a can be formed on the bottom surface 31.

(C) Next, the etching mask 29 is removed from one surface of the silicon substrate 27a by performing wet etching.
In the silicon substrate 27a subjected to the above-described process, the reaction vessel 15, the flow path 17 and the flow path 19 have convex shapes, the other portions become concave portions, and a mold 27b having fine irregularities 33a on the bottom surface 31 of the concave portions. It becomes.

(D) Using this mold 27b, the PDMS resin 13 is formed into a concavo-convex shape.
Since the fine unevenness 33a is formed only on the bottom surface 31 of the concave portion of the mold 27b, when the uneven shape of the mold 27b is transferred to the PDMS resin 13, the reaction vessel 15 and the flow paths 17, 19 of the base substrate 13 to be formed. The bottom surface 14 of the portion to become becomes smooth, and fine irregularities 33 b are formed on the surface of the base substrate 13.

(E) Finally, the fluid substrate is completed by bonding and joining the cover substrate 11 formed with the through holes as the liquid inlet 21 and the liquid outlet 23 to the base substrate 13.

  In this embodiment, a method for manufacturing a device in which the fine irregularities 25 are formed on one surface of the base substrate 13 is shown, but the fine irregularities 25 may be formed on one surface of the cover substrate 11.

  As another method for producing the fine unevenness 25 on the bonding surface of the substrate, the surface of the base substrate 13 is made fine by forming a resin such as PDMS using the substrate as a mold by roughening the surface of the metal substrate. May be formed. When the sandblasting method is used, the fine irregularities 25 can be formed at once on a wide area on the substrate, which is excellent from the viewpoint of the manufacturing process.

Next, the capillary force by the fluid device of the present invention will be described.
In FIG. 1, fine irregularities 25 are formed on the joint surface of the cover substrate 11 and the base substrate 13, and a gap is provided between the substrates 11 and 13. When the contact angle of the liquid sample with respect to the bonding surfaces of both substrates is 90 ° or more, when the liquid sample tries to enter this gap, a negative capillary force is received from the inner wall of the flow path. The pressure due to the capillary force at this time can be expressed by equation (1).

ここで、ΔPは毛細管力による圧力、ｗは微細凹凸２５の幅、ｄは微細凹凸２５の深さ、γ_LGは液体試料の界面張力、θは液体試料の基板に対する接触角である。

Here, ΔP is the pressure due to capillary force, w is the width of the fine irregularities 25, d is the depth of the fine irregularities 25, γ _LG is the interfacial tension of the liquid sample, and θ is the contact angle of the liquid sample with respect to the substrate.

  Since cos θ becomes negative when θ is 90 ° or more from the equation (1), ΔP becomes a large negative value when the size of the fine irregularities 25 is small with respect to the dimension of the flow path. It can be seen that the liquid sample is less likely to enter the gap between the substrates.

  Furthermore, when the absolute value of Δp obtained by substituting the unevenness dimensions into the equation (1) is larger than the liquid-sending pressure of the liquid sample, even when the liquid sample is sent into the device, It can be seen that the liquid sample does not enter.

  When a liquid sample is introduced into such a fluid device and air bubbles remain in the flow path or the reaction chamber, for example, when the sample outlet 23 is closed and pressure is applied from the sample inlet 21, the air forming the air bubbles is formed on both substrates. The air bubbles 11 and 13 are discharged to the outside of the fluid device, and the bubbles in the fluid device can be expelled to the outside.

  In the fluidic device of the present invention, the cover substrate 11 and the base substrate 13 are both made of PDMS, for example. When Dow Corning Sylgard184 is used for PDMS, the contact angle of deionized water with respect to the substrate surface is about 108 degrees.

  When the width and depth of the liquid introduction channel 17 are both 1 mm, the negative capillary force given by the equation (1) is about −90 Pa.

ここで、

である。 Moreover, the liquid feeding pressure at the time of flowing a liquid into a flow path is empirically represented by Formula (2).

here,

It is.

C _fr is a correction term relating to the flow path shape, and is about 96 when the flow path shape is a rectangular cross section. A is the cross-sectional area of the liquid introduction channel 17, L is the length of the liquid introduction channel 17, μ is the viscosity of the flowing liquid sample, and Q is the flow rate of liquid. For example, when the length of the liquid introduction channel 17 is 40 mm and deionized water is fed at 100 μL / min, the feeding pressure is about 192 Pa.

  When the shape of the fine irregularities 25 formed on the joint surface between the cover substrate 11 and the base substrate 13 is 1 μm wide and 0.5 μm deep, the negative capillary force given by the equation (1) is about −135 kPa. It is. That is, in the case of the above-described embodiment, since the negative capillary force generated in the gap between the substrates 11 and 13 is sufficiently large with respect to the liquid feeding pressure, the liquid sample does not enter the fine unevenness 25 as the gap.

  When bubbles remain in the channel or reaction chamber in this device, the sample discharge port 23 is closed, and a liquid sample is sent from the sample introduction port 21 at a pressure of several tens of kPa smaller than the absolute value of the capillary force. Only the gas component in the sample passes through the fine irregularities 25, and the bubbles can be removed from the liquid through the gap between the substrates 11 and 13.

  In the present embodiment, the flow of the liquid sample is controlled by closing the sample discharge port 23, but the same effect can be obtained by integrating microvalves in the device.

  An example of a fluidic device provided with such a microvalve is shown in FIG. The microvalve may be arranged in either of the channels 17 and 19, but in this embodiment, it is arranged in the liquid discharge channel 19. A valve lower recess 40 having the same depth as the flow path 19 is formed at a position where the valve is formed on the liquid discharge flow path 19 of the base substrate 13. The cover substrate 11 is formed with a pressure application portion 42 formed of a through hole having a size covering the valve lower recess 40 at a position where the valve is formed. For example, the size of the valve lower recess 40 is 3 mm in diameter, and the size of the pressure application unit 42 is 4 mm in diameter. A PDMS film 44 having a thickness of about 30 μm is sandwiched between the base substrate 13 and the cover substrate 11. The PDMS film 44 is previously perforated at the positions of the liquid inlet 21 and the liquid outlet 23. The base substrate 13 and the cover substrate 11 are joined together with the PDMS film 44 sandwiched therebetween to form a fluid device.

  By supplying air to the pressure application unit 42 from the outside at a pressure of about 100 kPa, the PDMS film 44 can be bent and the flow path 19 can be closed, and the air pressure is released and the PDMS film 44 is bent by the elastic force. By canceling, the channel 19 can be opened. The microvalve does not have to completely reduce the liquid flow rate. This is because by reducing the flow rate using the microvalve, the pressure of the liquid increases and bubbles are removed.

  Further, if the unevenness is formed as much as possible on the entire joint surface, bubbles can be removed from a wider area of the fluid device.

BRIEF DESCRIPTION OF THE DRAWINGS The schematic of the fluidic device in one Example is shown, (A) is a perspective view, (B) is a vertical sectional view in XX of (A). It is a flowchart explaining the manufacturing process of the fluid device in the Example. The schematic diagram of the conventional fluidic device is shown, (A) is a perspective view, (B) is the vertical sectional view in XX of (A). It is a figure which shows one Example of the fluid device provided with the microvalve, (A) is a top view, (B) is sectional drawing along a flow path.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Cover substrate 13 Base substrate 15 Reaction container 17 Liquid introduction flow path 19 Liquid discharge flow path 21 Liquid introduction port 23 Liquid discharge port 25 Fine unevenness 42 Microvalve pressure application part

Claims (5)

In a fluid device in which at least two members are bonded to each other and a flow path for flowing a liquid is formed by both members,
The material of the joint surface between the two members is selected so that the liquid flowing through the flow path has a contact angle of 90 ° or more with respect to the joint surface between the two members,
A gap is formed between the two members by forming irregularities on at least one of the joint surfaces between the two members,
The size of the gap is such that the absolute value of the pressure due to capillary force is larger than the pressure in the flow path in contact with the liquid gap flowing through the flow path, so that the gas is allowed to pass and the liquid is not allowed to pass. A fluid device, wherein the fluid device communicates from the flow path to the outside of the fluid device.   The fluid device according to claim 1, wherein the flow path is provided with a valve for controlling a flow of liquid.   The fluid device according to claim 1, wherein the unevenness has a height of 500 μm or less. At least two members including the base substrate and the cover substrate are bonded to each other to form a flow path through which the liquid flows, and an unevenness is formed on at least one of the joint surfaces between the two members, so that there is a gap between the two members. In the manufacturing method of the fluid device in which is formed,
The base substrate is resin-molded by using a mold in which a portion corresponding to the flow path is a convex portion and a portion corresponding to the bonding surface is a concave portion, and the bottom surface of the concave portion is formed with fine irregularities. Thus, a manufacturing method is characterized in that a flat substrate has a groove serving as a flow path, and the flat surface is formed as a base substrate having fine irregularities. The method of manufacturing a fluid device according to claim 4, wherein the mold is manufactured by including the following steps (A) to (C).
(A) A step of forming an etching resistant film on the surface of the silicon substrate, leaving the etching resistant film in a portion to be the flow path by photolithography and etching, and patterning to expose a portion to be a bonding surface,
(B) The silicon substrate having the etching-resistant film pattern is subjected to dry etching while alternately introducing an etching gas and an etching protective film forming gas, thereby forming a concave portion at a bonding surface and the concave portion. And (C) a step of removing the etching resistant film pattern after that.

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