JP5239871B2 - Microchip and manufacturing method of microchip - Google Patents

Description

  The present invention relates to a microchip in which a channel groove is formed and a method for manufacturing the microchip.

  A micro-analysis chip that uses microfabrication technology to form fine channels and circuits on silicon and glass substrates, and to perform chemical reactions, separation, and analysis of liquid samples such as nucleic acids, proteins, and blood in a minute space Alternatively, an apparatus called μTAS (Micro Total Analysis Systems) has been put into practical use. As an advantage of such a microchip, it is conceivable to realize an inexpensive system that can be carried in a small space because the amount of sample or reagent used or the amount of discharged waste liquid is reduced.

  The microchip is manufactured by bonding two members having at least one member subjected to fine processing. Conventionally, a glass substrate is used for the microchip, and various fine processing methods have been proposed. However, since glass substrates are not suitable for mass production and are very expensive, development of inexpensive and disposable resin macrochips is desired.

  In addition, in such an element that conducts an inspection by passing through a fine channel, such as a microchip, the surface of the channel has a hydrophilic property so that a liquid sample such as protein does not adhere to the channel. The process of giving is performed.

Examples of the treatment for imparting hydrophilic properties to the channel surface include organic / inorganic coating, plasma treatment, and surface modification by flowing a solution in the channel. Among them, the SiO ₂ film coating is sufficiently hydrophilic and is an inorganic material, so that it has advantages such as being stable as a material and having high transparency.

  In addition, as a method of bonding the microchip substrates, a method of bonding using an adhesive, a method of bonding the surface of a resin substrate with an organic solvent (for example, Patent Document 1), and bonding using ultrasonic fusion. There are a method (for example, Patent Document 2), a method for bonding using thermal fusion (for example, Patent Document 3), a method using laser fusion (for example, Patent Document 4), and the like.

Here, the configuration of the microchip according to the prior art will be described with reference to FIGS. FIG. 3 is a top view of a conventional microchip. 4 is a cross-sectional view of a microchip according to the prior art, and is a cross-sectional view taken along the line IV-IV in FIG. The microchip 100 includes a microchip substrate 110 having a microchannel 111 formed on the surface thereof, and a flat microchip substrate 120 for covering the microchannel 111. In the microchip substrate 110, a SiO ₂ film 112 is formed on the surface on which the fine channel 111 is formed. A SiO ₂ film 121 is also formed on the surface of the microchip substrate 120. Then, the microchip 100 is manufactured by bonding the microchip substrate 110 and the microchip substrate 120 with the adhesive 130 with the fine channel 111 inside. In addition, the microchip 100 is formed with an opening 113 for introducing a gel or a liquid reagent into the fine channel 111 or discharging the reagent from the fine channel 111. A reagent or the like is introduced into the fine channel 111 from the opening 113 or the reagent or the like in the fine channel 111 is discharged from the opening 113.
JP 2005-80569 A JP 2005-77239 A JP 2005-77218 A JP-A-2005-74796

When using an SiO ₂ film of the inorganic substance as a hydrophilic film, usually to form a SiO ₂ film in the bonding surface between the microchip substrates, as described above, the adhesive for bonding between the microchip substrates It is common to use. However, when the microchip substrates are bonded together using an adhesive, the adhesive may ooze out into the fine flow path and block the fine flow path. In addition, since the main component of the adhesive after curing is resin and has hydrophobicity, the hydrophilic function by the SiO ₂ film may be hindered.

In addition, organic solvent, ultrasonic fusion, thermal fusion, and laser fusion dissolve the surface of the resin substrate, making it difficult to maintain the shape of the micro-channel and deforming the bonding surface of the microchip. Flatness may be lost. If the flatness of the bonding surface is lost in this way, the bonding of the microchip substrate is insufficient, and it becomes difficult to bond the microchip substrate to the strength. As described above, it is difficult to join the surfaces on which the SiO ₂ films are formed.

  In addition, it is possible to make the inside of the fine channel hydrophilic by irradiating the surface of the microchip substrate with plasma, and then to join the microchip substrates to each other by the joining method described above. However, there has been a problem that hydrophilization is weakened due to aging, and is not stable.

  Further, after the polar polymer monomer is modified on the surface of the microchip substrate, the microchip substrates can be bonded to each other by the bonding method described above. However, there are problems such as compatibility with the resin microchip substrate and unevenness in surface modification.

  The present invention solves the above-described problem, and an object thereof is to provide a microchip that can be manufactured at a low cost with a small flow rate difference of a liquid sample in a fine channel, and a method for manufacturing the microchip. .

In the first embodiment of the present invention, a channel groove having a SiO ₂ film formed on the inner surface is formed on the surface of one of the two resin substrates, and the surface of the other resin substrate is The one resin substrate is subjected to an activation treatment, and the surface on which the channel groove is formed is on the inside, and the other resin substrate is on the surface on which the activation treatment is performed, The two resin substrates are joined , and the absolute value of the difference between the zeta potential of the inner surface of the channel groove and the zeta potential of the surface of the other resin substrate subjected to the activation treatment is: It is a microchip characterized by being 30 mV or less .

  A second aspect of the present invention is the microchip according to the first aspect, wherein the zeta potential on the inner surface of the flow path groove and the activation treatment of the other resin substrate are performed. Each of the zeta potentials of the surface is -80 mV to -40 mV.

The third embodiment of the present invention is the microchip of the first embodiment or the second embodiment, the zeta potential of the inner surface of the flow path groove, the activation of the other resin substrate The absolute value of the difference from the zeta potential of the surface subjected to is 10 mV or less.

According to a fourth aspect of the present invention, there is provided the microchip according to any one of the first to third aspects, wherein the thicknesses of the two resin substrates are 0.5 mm to 2.0 mm, respectively. It is characterized by being.

According to a fifth aspect of the present invention, there is provided the microchip according to any one of the first to third aspects, wherein one of the two resin substrates has a thickness of 0. The channel groove is formed on the surface at a thickness of 0.5 mm to 2.0 mm, and the other resin substrate has a thickness of 30 μm to 300 μm.

According to a sixth aspect of the present invention, there is provided the microchip according to any one of the first to fifth aspects, wherein a ratio between the depth D and the width L of the channel groove (D / L). Is 1-5.

A seventh aspect of the present invention is the microchip according to any one of the first to fifth aspects, wherein a ratio (D / L) between the depth D and the width L of the channel groove. Is 1-3.

An eighth aspect of the present invention is the microchip according to any one of the first to seventh aspects, wherein the two resin substrates are different in resin material.

A ninth aspect of the present invention is the microchip according to any one of the first to eighth aspects, wherein the thermal conductivity of the other resin substrate is 0.3 W / m · K or more. It is characterized by being.

According to a tenth aspect of the present invention, a channel groove is formed on the surface of one of the two resin substrates, and the surface on which the channel groove is formed is on the inside. A method of manufacturing a microchip for joining two resin substrates, wherein an SiO ₂ film is formed on a surface of the one resin substrate on which the channel groove is formed, and the other resin substrate is formed on the surface of the other resin substrate. the activation treatment at facilities Succoth for the zeta potential of the inner surface of the flow path grooves, the absolute value of the difference between the zeta potential of the surface which the activation process is performed in the other resin substrate, 30 mV or less , the one resin substrate has the surface on which the channel groove is formed on the inside, and the other resin substrate has the surface subjected to the activation treatment on the inside. A method of manufacturing a microchip, comprising bonding a resin substrate.

The first one embodiment of the present invention is a method of manufacturing a microchip according to a first 0 embodiment, and forming the SiO ₂ film CVD, sputtering, or by coating.

According to this invention, the inner surface of the channel can be hydrophilized by forming the SiO ₂ film on the inner surface of the channel groove. In addition, by activating the surface of the other resin substrate, a contact area can be secured on the bonding surface between the substrates, and the resin substrates can be bonded to each other satisfactorily. Moreover, since the surface of the other resin substrate is hydrophilized by activation, it is possible to join the resin substrates together and to hydrophilize the inner surface of the flow path. This makes it possible to manufacture a microchip with the inner surface of the flow path made hydrophilic at low cost. Further, by activating the surface of the other resin substrate, the difference in zeta potential from the SiO ₂ film formed in the channel groove can be reduced, and thereby the liquid sample in the channel can be reduced. It is possible to reduce the flow rate difference between the two.

It is sectional drawing of the microchip which concerns on embodiment of this invention. It is a table | surface which shows the conditions regarding the Example of this invention. It is a top view of the microchip based on a prior art. It is sectional drawing of the microchip based on a prior art, and is IV-IV sectional drawing of FIG.

Explanation of symbols

10, 13 Microchip substrate 11 Fine channel 12 SiO ₂ film

A microchip and a microchip manufacturing method according to an embodiment of the present invention will be described with reference to FIG.
(Configuration of microchip)
The microchip according to this embodiment includes a resin microchip substrate 10 and a microchip substrate 13. The microchip substrate 10 is formed with a groove-shaped fine channel 11. A SiO ₂ film 12 is formed on the inner surface of the fine channel 11. Further, the microchip substrate 13 which is a counterpart to which the microchip substrate 10 is bonded is a flat substrate, and the surface thereof is subjected to an activation process. Then, the microchip substrate 10 has the surface on which the fine flow path 11 is formed on the inside, and the microchip substrate 13 has the surface on which the activation process is performed on the inside, so that the microchip substrate 10 and the microchip substrate 13 are connected. Join. As a result, the microchip substrate 13 functions as a lid (cover) for the fine flow path 11. The microchip substrates 10 and 13 correspond to an example of the “resin substrate” of the present invention.

Further, the microchip substrate 10 is formed with a through hole formed through the substrate. This through-hole is formed in contact with the fine flow path 11, and becomes an opening for connecting the fine flow path 11 to the outside by joining the microchip substrate 10 and the microchip substrate 13. This opening is a hole for introducing, storing, and discharging the gel, sample, and buffer solution. The shape of the opening may be various shapes other than a circular shape and a rectangular shape. A tube or nozzle provided in the analyzer is connected to the opening, and a gel, sample, buffer solution, or the like is introduced into the microchannel 11 through the tube or nozzle, or from the microchannel 11. Discharge.
(Material of microchip substrate)
Resin is used for the microchip substrates 10 and 13. Examples of the resin include good moldability (transferability and releasability), high transparency, and low autofluorescence with respect to ultraviolet rays and visible light, but are not particularly limited. Absent. For example, polycarbonate, polymethyl methacrylate, polystyrene, polyacrylonitrile, polyvinyl chloride, polyethylene terephthalate, nylon 6, nylon 66, polyvinyl acetate, polyvinylidene chloride, polypropylene, polyisoprene, polyethylene, polydimethylsiloxane, cyclic polyolefin, etc. preferable. In particular, polymethyl methacrylate and cyclic polyolefin are preferable. The microchip substrate 10 and the microchip substrate 13 may use the same material or different materials.
(Shape of microchip substrate)
The microchip substrates 10 and 13 may have any shape as long as they are easy to handle and analyze. For example, a size of about 10 mm square to 200 mm square is preferable, and 10 mm square to 100 mm square is more preferable. The shape of the microchip substrates 10 and 13 may be matched to the analysis method and the analysis device, and a shape such as a square, a rectangle, or a circle is preferable.
(The shape of the fine channel)
The shape of the microchannel 11 is within the range of 10 μm to 200 μm in both width and depth in consideration of the fact that the amount of analysis sample and reagent used can be reduced, and the fabrication accuracy of molds, transferability, releasability, etc. Although it is preferable that it is the value of, it does not specifically limit. Further, if the aspect ratio (groove depth D / groove width L) is increased, the ratio of the inner surface of the microchannel 11 is increased, and therefore the influence of the microchip substrate 13 on which the SiO ₂ film is not formed is affected. Can be reduced. However, if the aspect ratio is too large, it is difficult to form the fine flow path 11 by molding or nanoimprinting. Practically, the aspect ratio is preferably 1 to 5, and more preferably 1 to 3. In order to simplify the description, the cross-sectional shape of the microchannel 11 shown in FIG. 1 is a rectangular shape, but this shape is an example of the microchannel 11 and is a curved surface. Also good.
(Thickness of microchip substrate)
Moreover, it is preferable that both the thickness of the microchip substrate 10 in which the microchannel 11 is formed and the thickness of the microchip substrate 13 functioning as a lid (cover) are 0.5 mm or more. If the thicknesses of the microchip substrates 10 and 13 are both 0.5 mm or more, the thickness of the microchip after bonding is 1.0 mm or more, so that the microchip substrates 10 and 13 may be bent during handling or setting to an analytical instrument. Because there are few. If there is little bend, the shearing force which becomes the force which peels a joining surface can be disperse | distributed over the whole surface, and a joining surface becomes difficult to peel. In particular, it is effective for maintaining the strength near the microchannel 11 and near the opening where the bonding force of the microchip substrate becomes weak. When the thickness of each of the microchip substrates 10 and 13 is thicker than 2 mm, it causes a material loss, an increase in weight, a decrease in transparency, and a decrease in thermal conductivity. Therefore, the thickness of the microchip substrates 10 and 13 is more preferably 0.5 mm to 2 mm.

Further, when the microchannel is not formed in the microchip substrate 13 functioning as a lid (cover), a film (sheet-like member) may be used instead of a plate-like member. In this case, the thickness of the film is preferably 30 μm to 300 μm, and more preferably 50 μm to 150 μm. In this way, by setting the thickness of the microchip substrate 13 serving as a lid (cover) to 30 μm to 300 μm, it is possible to use the flexibility of the film between the substrates in the vicinity of the fine flow path 11 and the opening that are difficult to bond. Can be sufficiently adhered to each other, and a good bonding state can be realized. Furthermore, by making the microchip substrate 13 into a film shape, there are effects such as cost reduction, weight reduction, transparency increase, and thermal conductivity improvement. If the thickness of the microchip substrate 13 is made thinner than 30 μm, the strength of the film itself is insufficient, and there is a possibility that the microchip substrate 13 may break during handling or setting to an analytical instrument. Further, if the thickness of the microchip substrate 13 is made larger than 300 μm, the flexibility of the film is lost, and it is not possible to sufficiently adhere the fine flow path and the vicinity of the opening which are difficult to be bonded, and bubbles are mixed between the substrates. There is a risk of it. By setting the thickness of the microchip substrate 13 to 0.5 mm or more, it can be handled as a plate material, so that it is possible to ensure planar accuracy by molding.

  Further, when electrophoresis is performed using a microchip, Joule heat is generated. Joule heat is represented by the product of applied voltage and current. When Joule heat is generated during electrophoresis, convection occurs in the solution, which may lead to a decrease in resolution. In addition, when the temperature rises due to Joule heat, the structure of the biopolymer itself such as protein, DNA, or RNA may change, resulting in a result different from the original separation. It is necessary to keep the Joule heat small and constant, attach a heat sink to the analytical instrument side, or use a resin material with high thermal conductivity for the microchip substrate.

For example, for the microchip substrate 10 on which the microchannel 11 is formed, a resin material having good moldability and good adhesion of the SiO ₂ film 12 is used, and the microchip substrate 13 functioning as a lid (cover) It is preferable to use a resin material that can be easily activated or a resin material that has good transparency and thermal conductivity. For example, it is preferable to use a resin material having a thermal conductivity of 0.3 W / m · K or more for the microchip substrate 13. Examples of resin materials having high thermal conductivity include high thermal conductivity polyphenylene sulfide resin (PPS) (thermal conductivity of 5 W / m · K) manufactured by Idemitsu Kosan Co., Ltd., and Toray's high thermal conductivity PPS resin (thermal conductivity of 10 W / m · K or more), power solution boards made by Matsushita Electronic Components (thermal conductivity is 3 W / m · K), and the like.
(Zeta potential)
Moreover, it is preferable that the zeta potential of the inner surface of the microchannel 11 formed on the microchip substrate 10 and the zeta potential of the surface of the microchip substrate 13 functioning as a lid (cover) are −80 mV to −40 mV. In this embodiment, by forming the SiO ₂ film 12 having a zeta potential of −60 mV, the zeta potential on the inner surface of the microchannel 11 can be set to −60 mV. Further, by applying an activation process to the substrate surface, the zeta potential of the surface of the microchip substrate 13 can be set to −80 mV to −40 mV.

Further, the absolute value of the difference between the zeta potential on the inner surface of the microchannel 11 and the zeta potential on the surface of the microchip substrate 13 functioning as a lid (cover) is preferably 30 mV or less, and the absolute value of the difference is 10 mV. The following is more preferable. In this embodiment, by activating the surface of the microchip substrate 13, the absolute value of the difference in zeta potential with the SiO ₂ film 12 formed on the inner surface of the microchannel 11 can be reduced to 30 mV or less. Further, a resin material in which the absolute value of the difference in zeta potential from the SiO ₂ film 12 formed on the inner surface of the microchannel 11 is 30 mV or less may be used for the microchip substrate 13.
(About zeta potential)
Here, the zeta potential will be described. Consider the electrical properties of the interface when a liquid is in contact with a solid surface. On the solid surface, ionization of dissociating groups such as carboxyl groups and amino groups occurs, the solid surface adsorbs positive or negative ions from the liquid and has a charge, or the dipole orientation of the solvent molecule occurs. Therefore, a potential difference is generated at the solid / liquid interface (hereinafter sometimes referred to as a solid-liquid interface). Since the entire system including the solid surface and the solution is kept electrically neutral, a non-uniform distribution of charge occurs near the interface. This is referred to as an interfacial electric double layer, and the zeta potential is obtained by experimentally determining the potential difference based thereon. In the microchip, since the ratio of the surface area of the fine channel to the volume is remarkably increased as compared with the conventional analysis system, the influence of the surface is increased. The zeta potential is an important indicator for controlling the solid-liquid interface of the microchannel.
(Measurement method of zeta potential)
In this embodiment, the zeta potential was measured using a zeta potential meter (ELS-Z2) manufactured by Otsuka Electronics Co., Ltd. Since the inner surface of the microchannel has a small surface area, it is difficult to measure the zeta potential of the inner surface. Therefore, a measurement was performed on the assumption that the inner surface of the microchannel 11 was formed by preparing a flat sample with the same resin as the microchip substrate 10 and forming an SiO ₂ film on the flat plate. Further, a flat plate sample was made of the same resin as that of the microchip substrate 13, and the flat plate was subjected to an activation treatment for measurement. For the measurement, latex monitor particles having no interaction with the flat plate sample (not adsorbed) were used.

  As described above, there is an electric double layer on the inner surface of the fine channel, and when an electric field is applied from the outside in parallel to the fine channel, the electric charge in the electric double layer moves, so the solvent in the fine channel is also Move with it. This phenomenon is called electroosmosis, and the flow is called electroosmotic flow. For example, considering a fine flow path of quartz glass, the surface of the quartz glass is negatively charged, so that positive ions and particles are collected near the inner surface of the fine flow path. When an electric field is applied, a flow toward the negative electrode occurs near the inner surface due to these ions and particles, and a flow in the opposite direction occurs near the center of the fine channel to compensate for the flow. When performing electrophoresis, in addition to the flow velocity of electrophoresis, it is necessary to consider an electroosmotic flow and a reverse flow generated by its reaction.

  Since the flow velocity of the electroosmotic flow is proportional to the electric field strength and the zeta potential, if the zeta potential is different on each surface inside the microchannel, a difference occurs in the flow velocity of the electroosmotic flow, and the liquid is used when performing electrophoresis. This will cause a hindrance to the uniformity of the sample flow rate.

Therefore, in the microchip according to this embodiment, the surface of the microchip substrate 13 that functions as a lid (cover) of the microchannel 11 is subjected to an activation process, so that SiO ₂ formed in the microchannel 11 is formed. The absolute value of the difference in zeta potential from the film 12 can be 30 mV or less. As a result, when electrophoresis is performed, the flow rate difference of the liquid sample can be reduced, and the uniformity of the flow rate can be maintained.

  Also, consider the case where DNA, RNA, and protein, which are biopolymers, are sieved according to the size of the molecule. Molecular sieving techniques include dialysis, gel filtration, capillary electrophoresis, gel electrophoresis, ultracentrifugation, etc., and any of these methods can be applied and applied to a microchip. Here, electrophoresis will be described as an example.

  When considering electrophoresis of DNA and RNA, DNA and RNA are negatively charged in the solution. Therefore, if the zeta potential on the surface of the microchannel is positive, the inner surface of the microchannel is positively charged, so that it attracts DNA and RNA electrically, and the DNA and RNA adhere to the surface of the microchannel. It becomes easy to do. On the other hand, if the zeta potential on the surface of the microchannel is negative, the inner surface of the microchannel is negatively charged, and thus electrically repels DNA and RNA. It becomes difficult to adhere. Therefore, it is desirable that the zeta potential on the surface of the fine channel is negative.

  Some proteins are positively or negatively charged in the solution. When performing SDS-polyacrylamide electrophoresis, which is a typical analysis method for proteins, SDS (sodium dodecyl sulfate) is bound to the protein and the whole is negatively charged. Therefore, when the inner surface of the fine channel is positively charged (when the zeta potential is positive), the protein is attracted electrically, and the protein is likely to adhere to the inner surface of the fine channel. On the other hand, if the zeta potential on the surface of the microchannel is negative, the inner surface of the microchannel is negatively charged, so that it repels electrically with the protein, making it difficult for the protein to adhere to the surface of the microchannel. . Therefore, it is desirable that the zeta potential on the surface of the fine channel is negative.

  Further, in the analysis using a microchip, it is conceivable to use solutions having various pHs, so it is also useful to measure the zeta potential at each pH. In this embodiment, the zeta potential is a neutral value (pH = 7).

In this embodiment, the SiO ₂ film 12 is formed on the inner surface of the fine channel 11. The zeta potential of the SiO ₂ film is −60 mV, which is a negative value. Furthermore, the zeta potential of the surface can be set to −80 mV to −40 mV by activating the surface of the microchip substrate 13 that functions as a lid (cover) for the fine channel 11. As a result, the inner surface of the microchannel and DNA, RNA, protein, etc. are electrically repelled, making it difficult for DNA, RNA, protein, etc. to adhere to the inner surface of the microchannel. In addition, since the SiO ₂ film has hydrophilicity, the solution can be easily introduced into the fine channel. Furthermore, since the SiO ₂ film is chemically stable, the hydrophilic function can be stably maintained.

By the way, in order to improve the uniformity of the flow velocity, an SiO ₂ film is formed not only on the inner surface of the microchannel 11 but also on the surface of the microchip substrate 13 that functions as a lid (cover) for the microchannel 11. preferably be covered by all the inner surface of the SiO ₂ film, but joining the microchip substrates each other resin forming the SiO ₂ film is technically difficult. For example, a method of joining the microchip substrates by activating the surfaces of the SiO ₂ film can be considered, but it is necessary to secure a contact area between the substrates. However, the SiO ₂ film is as hard as glass, and there is little deformation on the surface below the micrometer order even when pressure is applied. For this reason, when the SiO ₂ films are to be bonded to each other, the surface roughness Ra becomes a problem, and Ra ≦ 2 nm is required. Molded in to the Ra ≦ 2 nm is technically difficult, or improve with increasing molding cycle time, when the Ra ≦ 2 nm in molding can not be achieved, after forming the SiO ₂ film, or polishing an SiO ₂ film There is a need to. In such a case, there is a problem that costs and processes increase.

Therefore, in this embodiment, a SiO ₂ film is formed on the inner surface of the microchannel 11, and the soft resin surface is activated without forming the SiO ₂ film on the microchip substrate 13 functioning as a lid (cover). Thus, the microchip substrate 13 is flexibly deformed when pressure is applied during bonding. Thereby, a contact area can be ensured in the joining surface of the microchip substrates 10 and 13, and favorable joining is obtained. Further, since the surface of the microchip substrate 13 is made hydrophilic by the activation, the bonding and the hydrophilic treatment can be performed at the same time, and the microchip can be manufactured at a low cost. As a result, substantially the same effect can be obtained as when the entire inner surface of the flow path is covered with the SiO ₂ film.
(Production method)
Next, a method for manufacturing a microchip according to the above-described embodiment will be described. In this embodiment, the SiO ₂ film 12 is formed on the surface of the microchip substrate 10 where the fine flow path 11 is formed, and the surface of the microchip substrate 13 is activated. The microchip substrate 10 is bonded to the microchip substrates 10 and 13 with the surface on which the microchannels 11 are formed facing inward and the microchip substrate 13 with the surface subjected to the activation process facing inward. . Hereinafter, a method for forming the SiO ₂ film 12 and an activation process will be described.

First, the SiO ₂ film 12 is formed on the surface of the microchip substrate 10 where the fine flow path 11 is formed. At this time, the SiO ₂ film 12 is formed on the inner surface of the fine channel 11. The SiO ₂ film 12 is a film containing SiO ₂ as a main component, and may contain impurities other than SiO _{2 as} long as the hydrophilic function of the SiO ₂ film is maintained.

In addition to the inner surface of the microchannel 11, an SiO ₂ film may be formed not only on the surface (bonding surface) to be bonded to the microchip substrate 13 as shown in FIG. When forming the SiO ₂ film only on the inner surface of the microchannel 11, the surface of the microchip substrate 10 is masked to form the SiO ₂ film 12 so that the SiO ₂ film is formed only on the inner surface. On the other hand, when forming the SiO ₂ film to the surface (bonding surface) to be bonded to the microchip substrate 13, a SiO ₂ film is formed without masking the surface.
(Method for forming SiO ₂ film)
The SiO ₂ film 12 can be formed by, for example, vapor deposition, sputtering, CVD, or coating, and the film forming method is not particularly limited. A film forming method by coating, sputtering, or CVD is a more preferable method because an SiO ₂ film having good adhesion can be formed on the inner surface of the microchannel 11, particularly on the vertical wall surface of the microchannel 11.
(Example of forming SiO ₂ film by coating)
For example, when the SiO ₂ film 12 is formed by coating, a coating solution that becomes a SiO ₂ film after curing is applied to the surface of the microchip substrate 10, and then the coating solution is cured, whereby the surface of the microchip substrate 10. The SiO ₂ film 12 can be formed.

As the coating solution, for example, a solution obtained by dissolving a polysiloxane oligomer obtained by hydrolysis and condensation polymerization of alkoxysilane in an alcohol solvent is used. In this case, the coating solution is heated to volatilize the alcohol solvent to form a SiO ₂ film. Specific examples include Glassca 7003 manufactured by JSR, and methyl silicate 51 manufactured by Colcoat.

A solution obtained by dissolving perhydropolysilazane in a solvent of xylene and dibutyl ether is used as a coating solution. In this case, the coating solution is heated to volatilize the solvent and simultaneously react with water to form a SiO ₂ film. Specific examples include Aquamica manufactured by AZ Electronic Materials.

Moreover, what melt | dissolved the inorganic-organic hybrid polymer obtained by hydrolyzing and co-condensing an alkoxy silyl group containing polymer and alkoxysilane in the alcohol solvent is used for a coating solution. In this case, the alcohol solvent is volatilized by heating to form a hybrid film containing SiO ₂ as a main component. Specific examples include Glassca 7506 manufactured by JSR.
(Coating solution coating method)
It is important to apply the coating solution uniformly to the microchip substrate 10. The coating method is appropriately selected in consideration of the physical properties (viscosity and volatility) of the coating solution. Examples include dipping, spray coating, spin coating, slit coating, screen printing, pad printing, and ink jet printing.

Then, the SiO ₂ film 12 is formed by curing the coating solution. For example, when a thermosetting coating solution is used, the coating solution is cured by performing heat treatment to form the SiO ₂ film 12.
(Coating solution curing method)
When the coating solution is cured to form the SiO ₂ film, it is desirable that the solvent of the coating solution is sufficiently volatilized to form a strong network of SiO ₂ . The curing method is appropriately selected in consideration of the physical properties (viscosity, volatility, catalyst) of the coating solution. For example, the coating solution is allowed to cure at room temperature, the coating solution is cured by heating at a temperature of 60 ° C. to 100 ° C., or the coating solution is subjected to high temperature and high humidity (temperature 60%, humidity 90%, temperature). Curing at 80 ° C. and 90% humidity). Further, the coating solution may be cured using ultraviolet curing or visible light curing.
(Example of forming SiO ₂ film by sputtering)
In the case of forming the SiO ₂ film 12 by sputtering, for example, SYNCHRON manufactured sputtering apparatus (apparatus name: RAS-1100C) was used to form a SiO ₂ film 12. It is divided into a silicon metal deposition chamber and an oxidation chamber, and the SiO ₂ film 12 is formed by rotating the drum to which the substrate is attached. For example, the SiO ₂ film 12 was formed to a thickness of 200 nm under the conditions of an argon gas flow rate of 250 sccm, an oxygen gas flow rate of 120 sccm, an RF output of 4.5 kW, and a film formation rate of 4 Å / sec.
(Example of formation of SiO ₂ film by CVD)
In the case of forming the SiO ₂ film 12 by CVD, for example, Samco Co. CVD apparatus (apparatus name: PD-270ST) was using to form a SiO ₂ film 12. The SiO ₂ film 12 is formed by vaporizing a liquid source containing silicon, such as TEOS (Tetra Ethoxy Silane), TMOS (Tetra Ethoxy Silane), etc., and decomposing and oxidizing it in the plasma space. For example, the SiO ₂ film 12 was deposited to a thickness of 200 nm under the conditions of a TEOS flow rate of 12 sccm, an oxygen gas flow rate of 400 sccm, an RF output of 300 W, a pressure of 50 Pa, and a deposition rate of 30 Å / sec.
(Thickness of SiO ₂ film)
The film thickness of the SiO ₂ film 12 takes into consideration that the entire inner surface of the fine flow path 11 is covered with SiO ₂ , that the adhesion to the fine flow path 11 can be secured, and that the fine flow path 11 is not blocked. To decide. When forming the SiO ₂ film by coating, the film thickness is adjusted according to the characteristics and type of the coating solution. For example, a value within the range of 10 nm to 3 μm is preferable, and a value within the range of 10 nm to 2 μm is more preferable. Further, when a SiO ₂ film is formed by sputtering or CVD, and when a dense SiO ₂ film is formed, the internal stress of the SiO ₂ film tends to increase, so that the value is within a range of 10 nm to 1 μm. It is preferable that the value is within a range of 10 nm to 200 nm.

On the other hand, the microchip substrate 13 is activated on the substrate surface. Thereafter, the microchip substrate 10 has the surface on which the fine flow path 11 is formed facing inside, and the microchip substrate 13 joins both substrates with the surface subjected to the activation treatment facing inside.
(Method of activation)
Activation means that an atom or molecule obtains energy such as light and heat and enters a high energy state. In this embodiment, the surface of the microchip substrate 13 is activated when the organic matter attached to the surface of the microchip substrate 13 is decomposed and removed by irradiating it with high energy such as light and heat. This means that OH group bonds are generated on the surface and a chemical reaction is likely to occur. Examples of the activation method include ultraviolet irradiation, plasma irradiation, ion beam irradiation, ultrasonic cleaning, acid-alkali cleaning, heating, and the like, but are not particularly limited to these methods. Here, ultraviolet irradiation, ion irradiation, and plasma irradiation will be described in detail as an example of activation.
(Example of UV irradiation)
When the surface of the microchip substrate 13 is activated by ultraviolet irradiation, the substrate surface is preferably activated by irradiating the substrate surface with ultraviolet rays having a wavelength of 170 nm to 180 nm. For example, using an excimer light irradiation unit (model UER20-172C) manufactured by Ushio Electric Co., Ltd., excimer light irradiation is performed under the conditions of a wavelength of 172 nm and a radiation intensity of 10 mW / cm ^2. Activate. By irradiating the surface of the microchip substrate 13 with excimer light, a small amount of organic substances are decomposed and removed. In addition, excimer light directly acts on oxygen present in the space to generate active oxygen species such as excited oxygen atoms and ozone at high concentrations, decompose and remove trace amounts of organic substances, and generate OH group bonds. Thus, the surface of the microchip substrate 13 is activated.

For example, the optical energy of excimer light having a wavelength of 172 nm is 166.6 kcal / mol, which is higher than most of the molecular binding energy, and thus is effective for activating the surface of the microchip substrate 13.
(Example of ion beam irradiation)
Further, when the microchip substrate 13 is activated by ion beam irradiation, for example, an RF ion source (form OIS-two) manufactured by Optran Co., Ltd. is used, the oxygen gas flow rate is 50 sccm, the argon gas flow rate is 8 sccm, and the beam voltage. Is irradiated with an ion beam under conditions of 500 V, a beam current of 400 mA, and a degree of vacuum of 1.5 × 10 ⁻² Pa to activate the surface of the microchip substrate 13. By irradiating the surface of the microchip substrate 13 with oxygen ions and argon ions, a trace amount of organic substances are decomposed and removed, and OH group bonds are generated to activate the surface of the microchip substrate 13.
(Example of plasma irradiation)
When the microchip substrate 13 is activated by plasma irradiation, for example, a plasma dry cleaner (model PC-1000) manufactured by Samco Corporation is used, the oxygen gas flow rate is 200 sccm, the RF output is 400 W, and the degree of vacuum is 50 Pa. Plasma irradiation is performed under the above conditions to activate the surface of the microchip substrate 13. By irradiating the surface of the microchip substrate 13 with plasma, a trace amount of organic substances are decomposed and removed, and OH group bonds are generated to activate the surface of the microchip substrate 13. Gases, electrons, excited species, ions, and radicals exist in the plasma, and these act on the surface of the microchip substrate 13 to be activated.

As described above, by forming the SiO ₂ film on the inner surface of the microchannel 11, the inner surface of the microchannel 11 can be hydrophilized. Since the SiO ₂ film has a negative zeta potential, it is possible to suppress adhesion of proteins, DNA, and the like to the inner surface of the microchannel 11.

Further, by performing an activation process on the surface of the microchip substrate 13, it is possible to secure a bonding area and bond the microchip substrates 10 and 13 satisfactorily. Furthermore, since the surface of the microchip substrate 13 is hydrophilized by the activation treatment, the microchip substrates 10 and 13 can be joined and the inner surface of the flow path can be hydrophilized. This makes it possible to manufacture a microchip with the inner surface of the flow path made hydrophilic at low cost. Furthermore, by performing the activation treatment, the difference in zeta potential with the SiO ₂ film formed in the fine flow path 11 can be reduced. This makes it possible to reduce the flow rate difference of the liquid sample in the flow path and maintain the uniformity of the flow rate of the liquid sample.

Next, a specific embodiment will be described with reference to FIG. FIG. 2 is a table showing conditions relating to the example.
Example 1
(Microchip substrate)
A transparent polyolefin resin cyclic polyolefin resin (Zeonor, manufactured by Nippon Zeon Co., Ltd.) is molded by an injection molding machine, and a plurality of fine flow paths (aspects) having a width of 50 μm and a depth of 50 μm are formed on a plate member having an outer dimension of 50 mm × 50 mm × 1 mm. A flow path side microchip substrate composed of a plurality of through-holes having a ratio of 1) and an inner diameter of 2 mm was produced. This flow path side microchip substrate corresponds to the microchip substrate 10 in which the fine flow path 11 in the above embodiment is formed. Similarly, a cover side microchip substrate having an outer dimension of 50 mm × 50 mm × 1 mm was produced. This cover-side microchip substrate corresponds to the microchip substrate 13 that functions as a lid (cover) in the embodiment.
(Formation of SiO ₂ film)
Then, the flow path side microchip surface micro-channel is formed in the substrate (bonding surface), CVD device (SAMCO Inc., PD-270ST) to form a SiO ₂ film by using. As a CVD raw material, TEOS (Tetra Ethoxy Silane) was used. A SiO ₂ film having a thickness of 200 nm was formed at a flow rate of 12 sccm, an oxygen gas flow rate of 400 sccm, an RF output of 300 W, a pressure of 50 Pa, and a deposition rate of 30 Å / sec. By using a CVD apparatus, a SiO ₂ film could be uniformly formed inside a fine flow channel having a width of 50 μm and a depth of 50 μm. The thickness of the SiO ₂ film inside the fine channel was 130 nm.
(Activation process)
Using a plasma dry cleaner (model PC-1000) manufactured by Samco Co., Ltd. under conditions of an oxygen gas flow rate of 200 sccm, an RF output of 400 W, and a vacuum degree of 50 Pa, the SiO ₂ film on the flow path side microchip substrate and the cover side microchip The surface of the substrate was irradiated with plasma for 5 minutes. For the flow path side microchip substrate, the surface on which the fine flow path was formed (the surface on which the SiO ₂ film was formed) was irradiated with plasma. This activated the surface of the SiO ₂ film of the flow path side microchip substrate and the surface of the cover side microchip substrate. The contact angle of the surface of the cover side microchip substrate was about 10 °.

When the surface potential of the cover-side microchip substrate was measured, it was −20 mV before plasma irradiation, but it was confirmed that it changed to −55 mV after irradiation. Further, the surface potential of the flow path side microchip substrate was −60 mV.
(Joining)
Then, in order not to lose the active state of the substrate surface, after opening to the atmosphere within 5 minutes after the plasma irradiation, the flow path side microchip substrate and the cover side microchip substrate with the surface on which the fine flow path is formed facing inside Were bonded together with a force of 1 kgf / cm ² to bond the substrates together. In the first embodiment, the substrates are bonded to each other while being opened to the atmosphere. However, if the substrates are bonded together in a vacuum without being opened to the atmosphere after the plasma irradiation, the substrates can be bonded more firmly. By this joining, an opening having an inner diameter of 2 mm and a depth of 1 mm connected to the fine flow path was formed.
(Evaluation)
From the opening formed in the microchip, a viscous buffer solution containing a polymer was pressurized and injected into the fine channel, and then a fluorescently labeled DNA sample was injected. Further, electrodes were inserted into two locations of the opening of the microchip, electrophoresis was performed by applying a high voltage of 2000 V, and a DNA sample was detected by a fluorescence detector. In electrophoresis, it was observed that the labeled DNA sample was flowing in the fine channel at a uniform flow rate. Further, when the inside of the fine channel after the DNA sample passed was observed, no fluorescence was detected, and therefore it was confirmed that the DNA sample was not attached to the channel wall surface.
(Example 2)
(Microchip substrate)
A transparent polyolefin resin cyclic polyolefin resin (Zeonor, manufactured by Nippon Zeon Co., Ltd.) is molded by an injection molding machine, and a plurality of fine flow paths (aspects) having a width of 50 μm and a depth of 50 μm are formed on a plate member having an outer dimension of 50 mm × 50 mm × 1 mm. A flow path side microchip substrate composed of a plurality of through-holes having a ratio of 1) and an inner diameter of 2 mm was produced. This flow path side microchip substrate corresponds to the microchip substrate 10 in which the fine flow path 11 in the above embodiment is formed. Similarly, a cover side microchip substrate having an outer dimension of 50 mm × 50 mm × 1 mm was produced. This cover-side microchip substrate corresponds to the microchip substrate 13 that functions as a lid (cover) in the embodiment.
(Formation of SiO ₂ film)
Then, the flow path side microchip surface micro-channel is formed in the substrate (bonding surface), CVD device (SAMCO Inc., PD-270ST) to form a SiO ₂ film by using. As a CVD raw material, TEOS (Tetra Ethoxy Silane) was used. A SiO ₂ film having a thickness of 200 nm was formed at a flow rate of 12 sccm, an oxygen gas flow rate of 400 sccm, an RF output of 300 W, a pressure of 50 Pa, and a deposition rate of 30 Å / sec. By using a CVD apparatus, a SiO ₂ film could be uniformly formed inside a fine flow channel having a width of 50 μm and a depth of 50 μm. The thickness of the SiO ₂ film inside the fine channel was 130 nm.
(Activation process)
Using an excimer light irradiation unit (model UER20-172C) manufactured by Ushio Electric Co., Ltd., excimer light was applied to the surface of the flow path side microchip substrate and the cover side microchip substrate under the conditions of a wavelength of 172 nm and a radiation intensity of 10 mW / cm ^2. Irradiated for 2 seconds. The flow path side microchip substrate was irradiated with excimer light on the surface on which the fine flow path was formed (surface on which the SiO ₂ film was formed). This activated the surface of the SiO ₂ film of the flow path side microchip substrate and the surface of the cover side microchip substrate. The contact angle of the surface of the cover side microchip substrate was about 10 °.

When the surface potential of the cover-side microchip substrate was measured, it was −20 mV before excimer light irradiation, but it was confirmed that it changed to −50 mV after irradiation. Further, the surface potential of the flow path side microchip substrate was −60 mV.
(Joining)
Then, in order not to lose the active state of the substrate surface, within 1 minute after the excimer light irradiation, the flow path side microchip substrate and the cover side microchip substrate are combined with the surface on which the fine flow path is formed facing inside, and 1 kgf The substrates were bonded to each other with a force of / cm ² . By this joining, an opening having an inner diameter of 2 mm and a depth of 1 mm connected to the fine flow path was formed.
(Evaluation)
From the opening formed in the microchip, a viscous buffer solution containing a polymer was pressurized and injected into the fine channel, and then a fluorescently labeled DNA sample was injected. Further, electrodes were inserted into two locations of the opening of the microchip, electrophoresis was performed by applying a high voltage of 2000 V, and a DNA sample was detected by a fluorescence detector. In electrophoresis, it was observed that the labeled DNA sample was flowing in the fine channel at a uniform flow rate. Further, when the inside of the fine channel after the DNA sample passed was observed, no fluorescence was detected, and therefore it was confirmed that the DNA sample was not attached to the channel wall surface.
(Example 3)
(Microchip substrate)
A transparent polyolefin resin cyclic polyolefin resin (Zeonor, manufactured by Nippon Zeon Co., Ltd.) is molded by an injection molding machine, and a plurality of fine flow paths (aspects) having a width of 50 μm and a depth of 50 μm are formed on a plate member having an outer dimension of 50 mm × 50 mm × 1 mm. A flow path side microchip substrate composed of a plurality of through-holes having a ratio of 1) and an inner diameter of 2 mm was produced. This flow path side microchip substrate corresponds to the microchip substrate 10 in which the fine flow path 11 in the above embodiment is formed. Similarly, a cover side microchip substrate having an outer dimension of 50 mm × 50 mm × 1 mm was produced. This cover-side microchip substrate corresponds to the microchip substrate 13 that functions as a lid (cover) in the embodiment.
(Formation of SiO ₂ film)
Then, a SiO ₂ film having a thickness of 200 nm was formed on the surface (joint surface) on which the microchannels of the channel-side microchip substrate were formed using a CVD apparatus (PD-270ST, manufactured by Samco). As a CVD raw material, TEOS (Tetra Ethoxy Silane) was used. A SiO ₂ film having a thickness of 200 nm was formed at a flow rate of 12 sccm, an oxygen gas flow rate of 400 sccm, an RF output of 300 W, a pressure of 50 Pa, and a deposition rate of 30 Å / sec. By using a CVD apparatus, a SiO ₂ film could be uniformly formed inside a fine flow channel having a width of 50 μm and a depth of 50 μm. The thickness of the SiO ₂ film inside the fine channel was 130 nm.
(Activation process)
An RF ion source (type OIS-two) manufactured by OPTRAN Co., Ltd. was used, and the flow was performed under the conditions of an oxygen gas flow rate of 50 sccm, an argon gas flow rate of 8 sccm, a beam voltage of 500 V, a beam current of 400 mA, and a degree of vacuum of 1.5E-2 Pa. The surfaces of the roadside microchip substrate and the cover side microchip substrate were irradiated with an argon ion beam for 30 seconds. The channel-side microchip substrate was irradiated with an argon ion beam on the surface on which the microchannel was formed (the surface on which the SiO ₂ film was formed). This activated the surface of the SiO ₂ film of the flow path side microchip substrate and the surface of the cover side microchip substrate. The contact angle of the surface of the cover side microchip substrate was about 15 °.

When the surface potential of the cover-side microchip substrate was measured, it was −20 mV before the irradiation with the argon ion beam, but it was confirmed that the surface potential was changed to −48 mV after the irradiation. Further, the surface potential of the flow path side microchip substrate was −60 mV.
(Joining)
Then, in order not to lose the active state of the substrate surface, the atmosphere is released within 5 minutes after the irradiation with the argon ion beam, and the surface on which the microchannel is formed is set inside, and the channel side microchip substrate and the cover side micro The chip substrates were combined and pressed with a force of 1 kgf / cm ² to bond the substrates together. In Example 3, the substrates are bonded to each other while being opened to the atmosphere. However, if the substrates are bonded together in a vacuum without being released to the atmosphere after irradiation with an argon ion beam, bonding can be performed more firmly. By this joining, an opening having an inner diameter of 2 mm and a depth of 1 mm connected to the fine flow path was formed.
(Evaluation)
From the opening formed in the microchip, a viscous buffer solution containing a polymer was pressurized and injected into the fine channel, and then a fluorescently labeled DNA sample was injected. Further, electrodes were inserted into two locations of the opening of the microchip, electrophoresis was performed by applying a high voltage of 2000 V, and a DNA sample was detected by a fluorescence detector. In electrophoresis, it was observed that the labeled DNA sample was flowing in the fine channel at a uniform flow rate. Further, when the inside of the fine channel after the DNA sample passed was observed, no fluorescence was detected, and therefore it was confirmed that the DNA sample was not attached to the channel wall surface.
Example 4
(Microchip substrate)
A transparent polyolefin resin cyclic polyolefin resin (Zeonor, manufactured by Nippon Zeon Co., Ltd.) is molded by an injection molding machine, and a plurality of fine flow paths (aspects) having a width of 50 μm and a depth of 50 μm are formed on a plate member having an outer dimension of 50 mm × 50 mm × 1 mm. A flow path side microchip substrate composed of a plurality of through-holes having a ratio of 1) and an inner diameter of 2 mm was produced. This flow path side microchip substrate corresponds to the microchip substrate 10 in which the fine flow path 11 in the above embodiment is formed. Further, a film having a thickness of 0.1 mm was formed from a cyclic polyolefin resin, and cut into a size of 50 mm × 50 mm to produce a cover-side microchip substrate. This film-like cover-side microchip substrate corresponds to the microchip substrate 13 that functions as a lid (cover) in the embodiment.
(Formation of SiO ₂ film)
Then, the flow path side microchip surface micro-channel is formed in the substrate (bonding surface), CVD device (SAMCO Inc., PD-270ST) to form a SiO ₂ film by using. As a CVD raw material, TEOS (Tetra Ethoxy Silane) was used. A SiO ₂ film having a thickness of 200 nm was formed at a flow rate of 12 sccm, an oxygen gas flow rate of 400 sccm, an RF output of 300 W, a pressure of 50 Pa, and a deposition rate of 30 Å / sec. By using a CVD apparatus, a SiO ₂ film could be uniformly formed inside a fine flow channel having a width of 50 μm and a depth of 50 μm. The thickness of the SiO ₂ film inside the fine channel was 130 nm.
(Activation process)
Using a plasma dry cleaner (model PC-1000) manufactured by Samco Co., Ltd. under conditions of an oxygen gas flow rate of 200 sccm, an RF output of 400 W, and a vacuum degree of 50 Pa, the SiO ₂ film on the flow path side microchip substrate and the cover side microchip The surface of the substrate was irradiated with plasma for 5 minutes. For the flow path side microchip substrate, the surface on which the fine flow path was formed (the surface on which the SiO ₂ film was formed) was irradiated with plasma. This activated the surface of the SiO ₂ film of the flow path side microchip substrate and the surface of the cover side microchip substrate. The contact angle of the surface of the cover side microchip substrate was about 10 °.

When the surface potential of the cover-side microchip substrate was measured, it was −20 mV before plasma irradiation, but it was confirmed that it changed to −55 mV after irradiation. Further, the surface potential of the flow path side microchip substrate was −60 mV.
(Joining)
Then, in order not to lose the active state of the substrate surface, after opening to the atmosphere within 5 minutes after the plasma irradiation, the flow path side microchip substrate and the cover side microchip substrate with the surface on which the fine flow path is formed facing inside Were bonded together with a force of 1 kgf / cm ² to bond the substrates together. In Example 4, the substrates are bonded to each other while being opened to the atmosphere. However, if the substrates are bonded together in a vacuum without being released to the atmosphere after the plasma irradiation, the substrates can be bonded more firmly. By this joining, an opening having an inner diameter of 2 mm and a depth of 1 mm connected to the fine flow path was formed.
(Evaluation)
From the opening formed in the microchip, a viscous buffer solution containing a polymer was pressurized and injected into the fine channel, and then a fluorescently labeled DNA sample was injected. Further, electrodes were inserted into two locations of the opening of the microchip, electrophoresis was performed by applying a high voltage of 2000 V, and a DNA sample was detected by a fluorescence detector. In electrophoresis, it was observed that the labeled DNA sample was flowing in the fine channel at a uniform flow rate. Further, when the inside of the fine channel after the DNA sample passed was observed, no fluorescence was detected, and therefore it was confirmed that the DNA sample was not attached to the channel wall surface.
(Example 5)
(Microchip substrate)
A transparent polyolefin resin cyclic polyolefin resin (Zeonor, manufactured by Nippon Zeon Co., Ltd.) is molded by an injection molding machine, and a plurality of fine flow paths (aspects) having a width of 50 μm and a depth of 100 μm are formed on a plate member having an outer dimension of 50 mm × 50 mm × 1 mm. A flow path side microchip substrate composed of a plurality of through holes having a ratio of 2) and an inner diameter of 2 mm was produced. This flow path side microchip substrate corresponds to the microchip substrate 10 in which the fine flow path 11 in the above embodiment is formed. Similarly, a cover side microchip substrate having an outer dimension of 50 mm × 50 mm × 1 mm was produced. This cover-side microchip substrate corresponds to the microchip substrate 13 that functions as a lid (cover) in the embodiment.
(Formation of SiO ₂ film)
Then, the flow path side microchip surface micro-channel is formed in the substrate (bonding surface), CVD device (SAMCO Inc., PD-270ST) to form a SiO ₂ film by using. As a CVD raw material, TEOS (Tetra Ethoxy Silane) was used. A SiO ₂ film having a thickness of 200 nm was formed at a flow rate of 12 sccm, an oxygen gas flow rate of 400 sccm, an RF output of 300 W, a pressure of 50 Pa, and a deposition rate of 30 Å / sec. By using a CVD apparatus, a SiO ₂ film could be uniformly formed inside a fine flow channel having a width of 50 μm and a depth of 100 μm. The thickness of the SiO ₂ film inside the fine channel was 130 nm.
(Activation process)
Using a plasma dry cleaner (model PC-1000) manufactured by Samco Co., Ltd. under conditions of an oxygen gas flow rate of 200 sccm, an RF output of 400 W, and a vacuum degree of 50 Pa, the SiO ₂ film on the flow path side microchip substrate and the cover side microchip The surface of the substrate was irradiated with plasma for 5 minutes. For the flow path side microchip substrate, the surface on which the fine flow path was formed (the surface on which the SiO ₂ film was formed) was irradiated with plasma. This activated the surface of the SiO ₂ film of the flow path side microchip substrate and the surface of the cover side microchip substrate. The contact angle of the surface of the cover side microchip substrate was about 10 °.

When the surface potential of the cover-side microchip substrate was measured, it was −20 mV before plasma irradiation, but it was confirmed that it changed to −55 mV after irradiation. Further, the surface potential of the flow path side microchip substrate was −60 mV.
(Joining)
Then, in order not to lose the active state of the substrate surface, after opening to the atmosphere within 5 minutes after the plasma irradiation, the flow path side microchip substrate and the cover side microchip substrate with the surface on which the fine flow path is formed facing inside Were bonded together with a force of 1 kgf / cm ² to bond the substrates together. In Example 5, the substrates are bonded to each other while being opened to the atmosphere. However, if the substrates are bonded together in a vacuum without being released to the atmosphere after plasma irradiation, the substrates can be bonded more firmly. By this joining, an opening having an inner diameter of 2 mm and a depth of 1 mm connected to the fine flow path was formed.
(Evaluation)
From the opening formed in the microchip, a viscous buffer solution containing a polymer was pressurized and injected into the fine channel, and then a fluorescently labeled DNA sample was injected. Further, electrodes were inserted into two locations of the opening of the microchip, electrophoresis was performed by applying a high voltage of 2000 V, and a DNA sample was detected by a fluorescence detector. In electrophoresis, it was observed that the labeled DNA sample was flowing in the fine channel at a uniform flow rate. Further, when the inside of the fine channel after the DNA sample passed was observed, no fluorescence was detected, and therefore it was confirmed that the DNA sample was not attached to the channel wall surface.

As described above, according to the embodiment of the present invention, it is possible to hydrophilize the inner surface of the fine channel by forming the SiO ₂ film on the inner surface of the fine channel, and thereby the protein, DNA, etc. It becomes possible to suppress adhesion to the inner surface of the fine channel. In addition, by performing activation processing on the surface of the cover-side microchip substrate, it is possible to secure a bonding area and bond the substrates satisfactorily. Furthermore, the activation process can reduce the difference in zeta potential with the SiO ₂ film formed in the fine channel, thereby reducing the difference in the flow rate of the liquid sample in the channel and reducing the liquid flow rate. It is possible to maintain the uniformity of the sample flow rate. The materials of the microchip substrate, the SiO ₂ film formation method, the activation method, and the like shown in the first to fifth embodiments are merely examples, and the present invention is not limited to these.

Claims (11)

The surface of one resin substrate of the two resin substrates is formed with a channel groove having an SiO ₂ film formed on the inner surface, and the surface of the other resin substrate is subjected to an activation treatment. The two resin substrates are bonded to each other with the surface on which the flow channel groove is formed facing the inside and the other resin substrate facing the surface subjected to the activation treatment on the inside. The absolute value of the difference between the zeta potential of the inner surface of the channel groove and the zeta potential of the surface of the other resin substrate subjected to the activation treatment is 30 mV or less. Chip. Claim 1 and the zeta potential of the inner surface of the flow path grooves, each of the zeta potential of the surface which the activation process is performed in the other resin substrate, which is a -80mV~-40mV micro chip according to. Claims and zeta potential of the inner surface of the flow path groove, the absolute value of the difference between the zeta potential of the surface which the activation process is performed in the other resin substrate, characterized in that at 10mV or less The microchip according to claim 1 or claim 2 . The two thicknesses each of the resin substrate, the microchip according to any one of claims 1 or we claim 3, characterized in that the 0.5 mm to 2.0 mm. Of the two resin substrates, one resin substrate has a thickness of 0.5 mm to 2.0 mm, the channel groove is formed on the surface, and the other resin substrate has a thickness of 30 μm. the microchip according to claim 1 or we claim 3, characterized in that the ～300Myuemu. The microchip according to claim 1 or we claim 5 ratio between the depth D and the width L of the flow path groove (D / L) is equal to or 1-5. The microchip according to claim 1 or we claim 5 ratio between the depth D and the width L of the flow path groove (D / L) is equal to or is 1-3. The two resin substrates are microchip according to claim 1 or we claim 7, characterized in that the resin material is different. The microchip according to claim 1 or we claim 8 thermal conductivity of the other resin substrate is characterized in that it is 0.3 W / m · K or more. A channel chip is formed on the surface of one of the two resin substrates, and a microchip for joining the two resin substrates with the surface on which the channel groove is formed facing inside. A manufacturing method comprising:
SiO ₂ film is formed on a surface where the flow path groove is formed in the one of the resin base plate, with facilities Succoth activation treatment with respect to the other surface of the resin substrate, the flow path grooves The absolute value of the difference between the zeta potential of the inner surface and the zeta potential of the surface of the other resin substrate subjected to the activation treatment is set to 30 mV or less, and the one resin substrate has the channel groove. A method of manufacturing a microchip, characterized in that the two resin substrates are bonded with the formed surface facing inward and the other resin substrate facing in the surface subjected to the activation treatment. The method for manufacturing a microchip according to claim 10, wherein the SiO ₂ film is formed by CVD, sputtering, or coating.