JP2006181407A - Sheet made of pdms - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a micro-fluid device made of PDMS (polydimethylsiloxane) having eternal hydrophilic property or a microtiter plate and to provide its manufacturing method. <P>SOLUTION: In the sheet made of PDMS, a fine structure such as a recession-like well or a recession-like channel is arranged on at least one surface and a fine structure arrangement surface side has the eternal hydrophilicity. The sheet made of PDMS is manufactured by the method comprising (a) a step for preparing a master having a predetermined fine structure on an upper surface; (b) a step for pouring a mixture comprising PDMS prepolymer, a curing agent and a polyether modified surfactant to a fine structure formation surface side of the master; (c) a step for performing oxygen plasma treatment of the fine structure formation surface side of the molded sheet made of PDMS; and (d) a step for coating the fine structure formation surface side of the sheet made of PDMS with an organosilane solution. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to microtiter plates or microfluidic devices formed from polydimethylsiloxane (PDMS). More particularly, the present invention relates to microtiter plates or microfluidic devices that are made of PDMS but have permanent hydrophilicity.

  Recently, as is known by the names such as Microscale Total Analysis Systems (μTAS) or Lab-on-Chip, a micro that constitutes a microchannel with a predetermined shape in a substrate. Providing a fine structure such as a channel and a port and performing various operations such as chemical reaction, synthesis, purification, extraction, generation and / or analysis of substances within the fine structure has been proposed and partially put into practical use. A structure manufactured for such a purpose and having a fine structure such as a microchannel and a port in a substrate is collectively referred to as a “microfluidic device”. A microtiter plate having a number of fine wells (microwells) formed on the upper surface is also included in the μTAS category.

  Microfluidic devices and microtiter plates can be used for a wide range of applications such as genetic analysis, clinical diagnosis, drug screening and environmental monitoring. Microfluidic devices and microtiter plates are (1) significantly less sample and reagent usage, (2) shorter analysis times, (3) higher sensitivity, (4) on-site And can be analyzed on the spot, and (5) disposable.

  The material and structure of a conventional microfluidic device are proposed in Patent Document 1, for example. As shown in FIGS. 6A and 6B, the conventional microfluidic device 100 includes at least one microchannel (fine microchannel) on a substrate 101 such as a polymer sheet (for example, polydimethylsiloxane (PDMS)). A flow path) 102 is formed, and input / output ports 103 and 104 are formed at both ends of the microchannel 102, and a transparent or opaque material (for example, glass or a synthetic resin film) is formed on the lower surface side of the substrate 101. A facing substrate 105 made of is bonded. Due to the presence of the facing substrate 105, the ports 103 and 104 and the bottom of the microchannel 102 are sealed.

  The main uses of the I / O ports 103 and 104 are (a) injection of chemicals and samples (dispensing), (b) removal of waste liquids and products, and (c) supply of gas pressure (mainly for liquid delivery) Positive pressure and negative pressure), (d) release to the atmosphere (dispersion of internal pressure generated during pumping, release of gas generated by reaction), and (e) sealing (preventing liquid evaporation and deliberately reducing internal pressure) For the purpose of generating).

  Compared with glass, PDMS is not only easy to process microstructures, but also extremely stable against chemical liquids, sample liquids such as DNA and proteins, so it is generally used as a forming material for microfluidic devices and microtiter plates. Widely used.

  However, unlike glass, PDMS is generally hydrophobic and therefore has a low affinity for liquids. Therefore, when a liquid is injected into a microchannel or microwell in a PDMS substrate, the liquid may remain in the microchannel in the form of a droplet, or the liquid does not enter the microwell due to high surface tension. In some cases, it would flow out to the outside. For this reason, the process which makes PDMS hydrophilic is performed as needed.

As a method for making PDMS hydrophilic, for example, as described in Patent Document 2, a method comprising irradiating the surface of PDMS with vacuum ultraviolet light (excimer UV light) by an excimer has been proposed. Excimer UV light has various wavelengths depending on the type of discharge gas. For example, when the discharge gas is xenon (Xe ₂ ), excimer UV light having a center wavelength of 172 nm is obtained. An irradiation lamp that emits excimer UV light is, for example, a dielectric barrier discharge lamp in which xenon gas is sealed. This dielectric barrier discharge lamp enters an excimer state in which xenon atoms are excited (Xe ₂ ^* ), and emits light having a center wavelength of about 172 nm when dissociated from the excimer state into xenon atoms again. When this light having a central wavelength of 172 nm is irradiated to oxygen, ozone having a higher concentration than that obtained by irradiating oxygen having a central wavelength of 185 nm emitted from a conventional low-pressure mercury lamp can be obtained. An active oxidative degradation product is also obtained from The PDMS surface is rendered hydrophilic by the synergistic action of these high-concentration ozone and active oxidative degradation products.

  The disadvantage of the hydrophilic treatment of PDMS by excimer UV light is that the effect is transient and the hydrophilicity is lost over time. Therefore, what was hydrophilic immediately after manufacture may return to its original hydrophobicity when used, and this is a hydrophilic treatment method lacking in reliability. Therefore, development of a treatment method for making PDMS permanently hydrophilic has been strongly demanded, but a satisfactory hydrophilic treatment method has not yet been obtained.

JP 2001-157855 A Japanese Patent No. 2,705,023

Accordingly, an object of the present invention is to provide a PDMS microfluidic device or microtiter plate having permanent hydrophilicity.
Another object of the present invention is to provide a method of manufacturing a PDMS microfluidic device having permanent hydrophilicity.

  As a means for solving the above-mentioned problems, the invention according to claim 1 is characterized in that a fine structure such as a concave well or a concave channel is disposed on at least one surface, and the surface on which the fine structure is disposed has permanent hydrophilicity. It is a sheet made of PDMS characterized by having.

  Unlike the conventional temporary hydrophilic treatment with excimer UV light or the like, the PDMS sheet of the present invention has permanent hydrophilicity on the fine structure arrangement surface side. Maintains the same hydrophilicity.

  As a means for solving the above-mentioned problems, in the invention according to claim 2, the sheet made of PDMS contains a polyether-modified surfactant, and an organosilane coating is applied to the fine structure forming surface side. The PDMS sheet according to claim 1, wherein:

  Permanent hydrophilicity is obtained by the synergistic effect of the polyether-modified surfactant contained in the sheet and the organosilane coating on the microstructure-forming surface side.

  As a means for solving the above-mentioned problems, the invention according to claim 3 has a plurality of columnar protrusions protruding from the upper surface of the sheet, and has a concave well recessed downward from the upper surface of the columnar protrusion. 3. The PDMS sheet according to claim 1, wherein the columnar protrusions are isolated from each other by a gap.

  Since the well is formed on the upper surface of the columnar protrusions isolated from each other, the liquid injected into the well does not enter the other well. Therefore, an operation of injecting a very small amount of droplets such as nano-order into the well can be easily performed.

The invention according to claim 4 as means for solving the above-mentioned problems includes: (a) preparing a master having a predetermined microstructure on the upper surface;
(b) injecting a mixture of a PDMS prepolymer, a curing agent, and a polyether-modified surfactant on the microstructure-forming surface side of the master;
(c) performing a surface modification treatment on the fine structure forming surface side of the molded PDMS sheet with oxygen plasma or excimer UV light;
(d) A method for producing a PDMS sheet having permanent hydrophilicity, comprising the step of applying an organosilane solution to the fine structure forming surface of the PDMS sheet.

  After preparing a PDMS sheet by blending a polyether-modified surfactant with a mixture of a PDMS prepolymer and a curing agent and curing the mixture, the surface of the sheet on which the microstructure is formed is modified with oxygen plasma or excimer UV light. By applying an organosilane solution to the surface where the microstructure is formed, the polyether-modified surfactant, the surface modification treatment, and the organosilane coating are synergistically made permanent on the PDMS sheet. Hydrophilicity can be imparted.

  Manufacturing a hydrophilic sheet from PDMS is easier and cheaper than manufacturing a sheet having the same fine structure by processing hydrophilic glass. The hydrophilicity of the PDMS sheet by the conventional excimer UV light is transient, whereas the hydrophilicity of the PDMS sheet according to the present invention is permanent, and after a long period of time has elapsed since manufacture. Also, the same hydrophilicity as that immediately after the production can be maintained. Moreover, even if the size of the recess is a micro level, a very small amount of liquid can be injected into the recess very smoothly.

The present invention will be specifically described below with reference to the drawings. FIG. 1 is a process diagram illustrating an example of a method of manufacturing a PDMS microtiter plate having permanent hydrophilicity according to the present invention. In step (A), a master (mold) 1 having an inverted shape of the microtiter plate is prepared. Such a master 1 can be easily molded by a conventional photolithography method. For example, a silicon wafer (for example, a 4-inch wafer) 3 having a desired size is prepared. The silicon wafer can be dried in advance or subjected to a desired pretreatment such as a surface treatment. Thereafter, a suitable resist material (for example, negative photoresist SU-8) is spin-coated at a rotational speed of 2000 rpm to 5000 rpm for several seconds to several tens of seconds and dried in an oven to form a resist film having a desired thickness. Form. Next, a mask is placed on the resist film, and exposure is performed through an appropriate exposure apparatus through the mask. The mask has a layout pattern corresponding to the wells of the microtiter plate to be manufactured. Then, it develops in a suitable developing solution (for example, 1-methoxy-2-propylacetic acid), The master 1 which has the fine structure 5 corresponding to the well of a microtiter plate on the upper surface is shape | molded. The microstructure 5 is, for example, a cylindrical protrusion having a diameter of 600 μm and a height of 100 μm. Of course, other shaped microstructures can be used. If desired, the master 1 can be washed with an organic solvent (for example, isopropyl alcohol) and distilled water. Furthermore, the surface of the master 1 can be treated with a reactive ion etching system in the presence of fluorocarbon (CHF ₃ ). This reactive ion etching treatment in the presence of fluorocarbon has an effect of easily releasing the PDMS microtiter plate from the master 1 in a later step.

  In step (B), the PDMS prepolymer mixed solution and the polyether-modified silicone surfactant are uniformly mixed in an appropriate ratio, and the resulting mixture is degassed to remove bubbles and then onto the upper surface of the master 1. Pour. At this time, it is preferable that a mold is used to form a casting mold, and the mixture is poured into the casting mold. After casting, it is allowed to stand at room temperature for a sufficient time, or for example, heated in an oven at 65 ° C. for 4 hours or cured at 100 ° C. for 1 hour to cure, thereby forming a PDMS microtiter plate 7.

  As the PDMS prepolymer mixed solution, for example, SYLGARD 184 SILICONE ELASTOMER manufactured by Dow Corning, USA can be suitably used. This is a mixture of a liquid PDMS prepolymer and a curing agent in a ratio of 10: 1. Needless to say, other PDMS prepolymer mixtures and / or mixing ratios can be used as well. The polyether-modified silicone surfactant that can be used in the present invention is, for example, a silicone surfactant commercially available from Dow Corning Asia Co., Ltd. under the product name DK Q8-8011. The blending amount of the polyether-modified silicone surfactant with respect to the PDMS prepolymer mixed solution is in the range of 0.005 wt% to 10 wt% based on the weight of the PDMS prepolymer mixed solution. When the blending amount of the polyether-modified silicone surfactant is less than 0.005 wt%, the final product PDMS microtiter plate cannot be made permanently hydrophilic. On the other hand, if the blending amount of the polyether-modified silicone surfactant exceeds 10 wt%, the final product PDMS microtiter plate becomes cloudy, making measurement analysis by optical detection impossible. More preferably, it is in the range of 2 wt% to 9 wt%.

In step (C), the PDMS microtiter plate 7 is peeled from the master 1, and the surface on which the well 9 is formed is subjected to surface modification treatment. The surface modification treatment is preferably performed by O ₂ plasma or excimer UV light. Other surface modification methods can also be used. The PDMS surface is modified by irradiating the PDMS surface with oxygen plasma or excimer UV light. It is considered that a hydroxyl group is formed on the PDMS surface by irradiation with oxygen plasma or excimer UV light, and the permanent hydrophilicity of the microtiter plate 7 is achieved by the action of the hydroxyl group.
The O ₂ plasma treatment can be performed using, for example, a compact etcher model FA-1 commercially available from Samco International Laboratory. The reactor of this apparatus is made of quartz, and the sample stage is made of water-cooled aluminum. The high-frequency power source is 13.56 MHz crystal oscillation, and the maximum output is 200 W. After the inside of the etcher is purged with N ₂ , processing is performed by discharging O ₂ plasma for 1.7 seconds under the conditions of a pressure of 0.01 MPa, a flow rate of 26 mL / min, an oxygen concentration of 99.99995% or more, and an RF output of 30 W.
As an irradiation lamp that emits excimer UV light, for example, a xenon gas filled dielectric barrier discharge lamp commercially available from USHIO INC. Can be used. Irradiation intensity of the excimer UV light is ^generally in the range of 1mW / cm ² ~30mW / cm 2 is preferred. When the irradiation intensity is less than 1 mW / cm ² , the desired surface modification effect cannot be obtained, or the processing time becomes too long and the working efficiency is lowered. On the other hand, when the irradiation intensity is more than 30 mW / cm ² , the irradiation effective area is small and the size of the object to be processed is limited. Further, since a plurality of lamps are arranged in close contact, the irradiation intensity varies, and as a result, the degree of processing may be uneven. In general, the excimer UV light irradiation time is preferably in the range of 5 seconds to 5 minutes. The irradiation time of the excimer UV light has a reciprocal relationship with the irradiation intensity. When the irradiation intensity is high, the irradiation time is shortened. The optimum irradiation time for the irradiation intensity of the selected irradiation lamp can be easily determined by those skilled in the art by repeating the experiment.

In step (D), an organosilane solution 11 is applied to the well 9 forming surface side of the surface-modified PDMS microtiter plate 7. The organosilane that can be used in the present invention is, for example, polyether-modified alkoxysilane. Such an organosilane is commercially available from Shin-Etsu Chemical Co., Ltd. and can be easily obtained.
As the organosilane, those having a main chain composed of siloxane units and containing a polyoxyethylene chain and an alkoxy group at the terminal or side chain are suitable. The molecular structure may be any structure such as linear, cyclic, or partially branched linear. The alkoxy group may be alkoxysilyl bonded to the main chain silicon atom via an alkylene chain or alkyleneoxyalkylene chain, or may be one in which the alkoxy group is directly bonded to the main chain silicon atom. Examples of the alkoxysilyl group bonded to the silicon atom of the main chain through an alkylene chain or an alkyleneoxyalkylene chain include a trialkoxysilyl group and a methylene dialkoxysilyl group, such as an ethylene chain, a propylene chain, an ethyleneoxyethylene chain, and an ethyleneoxy group. And a group bonded to the silicon atom of the main chain through a propylene chain. Examples of the alkoxy group include a methoxy group, an ethoxy group, a propoxy group, an isopropoxy group, and a butoxy group. The polyoxyethylene chain is generally bonded to the main chain silicon atom via an alkylene chain, but may be directly bonded to the main chain silicon atom. In the organosilane, in addition to the alkoxy group and the polyoxyethylene chain, examples of the group bonded to the silicon atom include alkyl groups such as methyl, ethyl, and butyl, alkenyl groups such as vinyl, allyl, and butenyl, and phenyl. An aromatic hydrocarbon group etc. are mentioned.
As a solvent for producing the organosilane solution, any solvent such as water, alcohols, ketones and ethers can be appropriately used. The concentration of the organosilane solution is preferably about 1 wt% to 10 wt%. If the concentration of the organosilane solution is less than 1 wt%, the desired hydrophilicity cannot be obtained. On the other hand, when the concentration of the organosilane solution is more than 10 wt%, PDMS becomes cloudy, which is not preferable because optical observation becomes difficult. A concentration of about 2 wt% is particularly preferred.

  Arbitrary methods can be used for the coating method of the organosilane solution. For example, various coating methods such as brush coating, dip coating, spray coating, roller coating, blade coating, and spin coating can be used. After applying the organosilane solution, the PDMS microtiter plate 7 is dried at a temperature of 80 ° C. to 100 ° C. for 1 hour. When the temperature is less than 80 ° C., no siloxane bond is generated and the desired hydrophilicity is not exhibited. It is preferable to dry at a temperature of 100 ° C.

  FIG. 2A is a schematic diagram showing a state in which a liquid droplet 13 is dropped in a well 9B of a PDMS microtiter plate 7B made only from a conventional PDMS prepolymer mixed solution. Since PDMS itself is hydrophobic, the liquid remains in the form of droplets and remains at the top of the well, and does not fill the well. On the other hand, FIG. 2 (B) is a schematic view showing a state in which a liquid droplet 13 is suspended in a well 9 of a PDMS microtiter plate 7 manufactured by the method of the present invention. Since the PDMS microtiter plate 7 manufactured by the method of the present invention has a permanent hydrophilic property, when the liquid droplet 13 is dropped on the well 9, the droplet 9 is immediately filled into the well 9.

  FIG. 3 is a schematic cross-sectional view of another form of permanent hydrophilic PDMS microtiter plate according to the present invention. In this form of the PDMS microtiter plate 15, there are a plurality (for example, 96) of columnar protrusions 17 protruding from the upper surface of the plate, and wells 19 that are recessed from the upper surface of the columnar protrusion 17 are formed. The columnar protrusions 17 may be either cylindrical or prismatic. Therefore, the shape of the well 19 can also be an arbitrary shape such as a columnar shape or a prismatic shape. As an example, the columnar protrusion 17 has an outer diameter of 1 mm and a height of 350 μm. Needless to say, columnar protrusions 17 of other sizes can also be used. For example, the well 19 has a depth of 100 μm and an inner diameter of 600 μm. The depth and inner diameter of the well 19 can be selected in consideration of the volume of the droplets contained in the well 19. The columnar protrusions 17 are separated from each other by a gap 20. The space | interval of the space | gap 20 can be made into arbitrary values.

  A feature of the microtiter plate 15 having the shape shown in FIG. 3 is that the wells 19 are completely independent from each other and are isolated from each other due to the presence of the gap 20. Therefore, as shown in FIG. 4, even if the liquid droplet 13 injected into the well 19 overflows from the well 19, it flows along the outer wall surface of the columnar protrusion 17 and flows down into the gap 20 of the microtiter plate 15. , Never flows into the adjacent well 19. In the case of the microtiter plate 7 shown in FIG. 2B, if the volume of the droplet 13 injected into the well 9 is larger than that of the well 9, the overflowing droplet flows into the adjacent well 9, which is inconvenient. It can cause unexpected situations. Therefore, compared to the microtiter plate 7 shown in FIG. 2B, the microtiter plate 15 having the shape shown in FIG. 3 can be implemented without paying unnecessary attention to the operation of injecting droplets. There is an advantage. This advantage is particularly effective when the volume of droplets injected into the well is extremely small such as nano-order.

  FIG. 5 is a process diagram illustrating an example of a manufacturing method of the microtiter plate 15 shown in FIG. In step (a), a semi-molded mold 21 is prepared. The primary mold 21 has a resist protrusion 23 corresponding to the well 9 and a half resist protrusion 25 for forming a gap 20 between the columnar protrusions 17 on the upper surface thereof. Next, in step (b), a new resist layer 27 is further laminated on the upper surface of the resist protrusion 25 of the semi-molded mold 21 to obtain a desired completed mold 29. Such a semi-manufactured mold and a finished mold can be produced by the same method as described in FIG. Next, in step (c), the PDMS prepolymer mixed solution and the polyether-modified silicone surfactant are uniformly mixed at an appropriate ratio, the resulting mixture is deaerated to remove bubbles, and then the finished mold is removed. Pour into the top of 29. This casting mixture is the same as the casting mixture used in step (B) of FIG. Next, in step (d), the PDMS microtiter plate 15 is peeled from the completed mold 29, and the surface on which the well 19 is formed is subjected to surface modification treatment. The surface modification treatment method used here is the same as the surface modification treatment method used in step (C) of FIG. Thereafter, in step (e), the organosilane solution 11 is applied to the well 19 forming surface side of the surface-modified PDMS microtiter plate 15 and dried. The organosilane solution 11 used here is the same as the organosilane solution 11 used in step (D) of FIG. In this way, a permanently hydrophilic PDMS microtiter plate 15 having a caldera-type well is obtained.

  The hydrophilicity obtained by the method of the present invention is preferably 40 ° or less in terms of the contact angle with water. If the contact angle with water exceeds 40 °, the wettability necessary to smoothly fill the droplets in the fine well 9 cannot be obtained. In order to achieve the predetermined wettability, it is necessary to use a primary hydrophilization treatment with a surfactant, a surface modification treatment, and a secondary hydrophilization treatment with an organosilane solution. Even if any one of them is missing, hydrophilicity with a contact angle of 40 ° or less cannot be obtained. For example, in the case of only the primary hydrophilic treatment and the surface modification treatment, permanent hydrophilicity with a contact angle with water of 40 ° or less cannot be obtained. The contact angle temporarily becomes 20 ° or less, but the contact angle returns to 50 to 70 ° as time passes. In the case of only surface modification treatment and secondary hydrophilization treatment, the contact angle is only about 100 ° to 110 °. In the case of only the primary hydrophilic treatment and the secondary hydrophilic treatment, the contact angle is only about 50 to 70 °. The smaller the volume of the well 9 or 19, the more permanent and highly hydrophilic it is necessary.

First, a 4-inch wafer was prepared. In order to obtain process reliability, it is necessary to clean and dry the substrate before using the resist. In this embodiment, after the piranha etching / clean (H ₂ SO ₄ and H ₂ O ₂ ) treatment, the distillation is performed. Rinse with water. Thereafter, in order to remove the surface oxide film of silicon, it was immersed in BHF (buffered hydrofluoric acid) for 15 minutes and rinsed with distilled water. Then, in order to dehydrate the surface, it was baked at 60 ° C. for about 30 minutes in a convection oven. On this surface-treated wafer, SU-8 negative photoresist was applied at a rotational speed of 1000 rpm for about 25 seconds, the solvent was evaporated, and soft baking was performed at 65 ° C. for 30 minutes (STEP 1). It processed at 95 degreeC for 90 minutes (STEP2). After cooling, this resist film was covered with a mask having a 96-hole pattern with a diameter of 600 μm and a hole-to-hole interval of 1 mm, and contact exposure was performed with an exposure apparatus (PEM-800 manufactured by Union Optics). Thereafter, in order to crosslink the exposed portion of the resist film, the film is heated at 65 ° C. for 15 minutes (STEP 1) and at 95 ° C. for 25 minutes (STEP 2). After cooling, development with a 1-methoxy-2-propylacetic acid developer is performed. After development, the substrate was rinsed with isopropyl alcohol (IPA) for a short time. Then, after drying at 65 ° C. for 30 minutes, it was hard baked at 150 ° C. for 5 minutes to complete a master having 96 cylindrical protrusions with a diameter of 600 μm and a height of 100 μm on the surface.

The surface of this master was treated with a reactive ion etching system in the presence of fluorocarbon (CHF ₃ ) to form a CHF ₃ release film on the surface. SYLGARD 184 SILICONE ELASTOMER manufactured by Dow Corning, USA is used as a PDMS prepolymer mixture on the release film forming surface of the master, and a polyether-modified silicone surfactant (Dow DK Q8-8011) commercially available from Corning Asia Co., Ltd. was added at 8 wt% based on the weight of the PDMS prepolymer mixture and mixed until all components were uniform. Thereafter, the obtained mixture was poured into a thickness of about 2 mm, deaerated and heated (65 ° C., 4 hours). After 4 hours, it was removed from the oven and the PDMS microtiter plate was peeled off from the master.

Thereafter, the PDMS microtiter plate was accommodated in the plasma processing apparatus, the apparatus was sealed, and the inside of the etcher was purged with N ₂ , and then pressure 0.01 MPa, flow rate 26 mL / min, oxygen concentration 99.99995% or more, Under conditions of an RF frequency of 13.56 MHz and an output of 30 W, O ₂ plasma was discharged for 1.7 seconds to surface-treat the well formation surface side of the PDMS microtiter plate.

  The plasma-treated PDMS microtiter plate was taken out from the plasma processing apparatus, and a 2% polyether-modified alkoxysilane aqueous solution was dip coated on the well forming surface to remove the excess aqueous solution. Thereafter, it was placed in an oven at 100 ° C. and dried for 1 hour. In this way, a 96-well PDMS microtiter plate was produced.

Comparative Example 1

  A 96-well PDMS microtiter plate was prepared according to the same method as described in Example 1 except that the polyether-modified silicone surfactant was not added to the PDMS prepolymer mixed solution.

Comparative Example 2

A 96-well PDMS microtiter plate was prepared according to the same method as described in Example 1 except that the O ₂ plasma treatment was omitted.

Comparative Example 3

  A 96-well PDMS microtiter plate was prepared according to the same method as described in Example 1 except that the 2% polyether-modified alkoxysilane aqueous solution was not applied.

  A 1 μl (microliter) water droplet was dropped into the well of each PDMS microtiter plate obtained in Example 1 and Comparative Examples 1 to 3, respectively. In the PDMS microtiter plate of Example 1, the well was filled with water, but in the case of the PDMS microtiter plates of Comparative Examples 1 to 3, the water droplets stayed at the upper part of the well and could not enter the well. It was.

  Water droplets were dropped on the surface of each PDMS microtiter plate obtained in Example 1 and Comparative Examples 1 to 3, and the contact angle with water was measured using a contact angle meter. In the case of the PDMS microtiter plate of Example 1, the contact angle was 40 ° or less, whereas in the case of the PDMS microtiter plate of Comparative Example 1, the contact angle was 100 to 110 °. And 3 PDMS microtiter plates had a contact angle of 50-70 °.

  The present invention is not limited to a microtiter plate, but is a PDMS microfluidic device having a fine structure such as a microchannel, and the microfluidic device made of PDMS that requires permanent hydrophilicity for the fine structure such as a microchannel. Can be applied. In addition, the present invention can be applied to all PDMS devices other than microfluidic devices that require permanent hydrophilicity.

It is process drawing which illustrates an example of the manufacturing method of the PDMS microtiter plate which has the permanent hydrophilic property by this invention. (A) is a schematic view showing a state in which droplets are dropped on wells of a conventional hydrophobic PDMS microtiter plate, and (B) is a well of a PDMS microtiter plate having permanent hydrophilicity according to the present invention. It is a schematic diagram which shows the state which dripped the droplet. It is a partial schematic sectional drawing of another form of the microtiter plate made from PDMS which has permanent hydrophilic property by this invention. FIG. 4 is a partial schematic cross-sectional view showing a usage state of the microtiter plate shown in FIG. 3. FIG. 4 is a process diagram illustrating an example of a method for manufacturing the microtiter plate shown in FIG. 3. (A) is a general | schematic top view of an example of the conventional microfluidic device, (B) is a schematic sectional drawing in alignment with the BB line in (A).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Master 3 Silicon wafer 5 Microstructure 7 PDMS microtiter plate 9 Well 11 Organosilane solution 13 Droplet 15 Another form of PDMS microtiter plate 17 Columnar protrusion 19 Well 20 Air gap 21 Semi-made molds 23, 25, 27 Resist Layer 29 Finished mold 100 Microfluidic device 101 Polymer sheet substrate 102 Microchannel 103, 104 Port 105 Face-to-face substrate

Claims (4)

A PDMS sheet, wherein a fine structure such as a concave well or a concave channel is disposed on at least one surface, and the surface on which the fine structure is disposed has permanent hydrophilicity. 2. The PDMS sheet according to claim 1, wherein the PDMS sheet contains a polyether-modified surfactant, and an organosilane coating is applied to the fine structure forming surface side. It has a plurality of columnar protrusions protruding from the upper surface of the sheet, has a concave well recessed downward from the upper surface of the columnar protrusion, and the columnar protrusions are isolated from each other by a gap. The PDMS sheet according to claim 1 or 2. (a) preparing a master having a predetermined microstructure on the upper surface;
(b) injecting a mixture of a PDMS prepolymer, a curing agent, and a polyether-modified surfactant on the microstructure-forming surface side of the master;
(c) oxygen plasma treatment of the microstructured surface side of the molded PDMS sheet;
(d) A method for producing a PDMS sheet having permanent hydrophilicity, comprising the step of applying an organosilane solution to the microstructure-forming surface side of the PDMS sheet.

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