JP2006300145A - Micro valve and micro chip having the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a micro valve manufacturable at low cost and providing such a high reliability that does not cause troubles such as defective contact during use. <P>SOLUTION: This micro valve comprises a valve member disposed to stop the passing of a fluid and allowing the fluid to pass therethrough in a fluidized state when heat is given thereto and a heating part heating the valve member by an induced current generated by an alternating magnetic field applied from the outside thereto. When the magnetic field is applied to the heating part when the valve is opened, an induced current occurs in the heating part to generate heat from the heating part, and the valve member is heated and molten or gelated, and the liquid is allowed to pass therethrough. Since the micro valve does not require accurate machining in manufacture and also an electrode manufacturing step, it can be manufactured at low cost. Furthermore, the micro valve does not cause the troubles such as defective contact during use, its reliability is increased. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a microvalve that controls movement of a sample, a chemical solution, or the like (hereinafter, “sample etc.”) in a microchip having a microchannel or a nanochannel such as a biochip and a DNA analysis chip.

  In recent years, in the field of analytical chemistry, μTAS (Micro Total Analysis Systems) has been actively researched. The microchip used in such research can perform chemical analysis, bioanalysis, DNA analysis, etc. with a small amount of sample in a short time and at a low cost. It is expected that many effects can be obtained, such as the need for environmental control such as equipment and constant temperature and humidity, and further the automation of analysis work.

  When chemical analysis, bioanalysis, DNA analysis, etc. are performed using this microchip, the sample is a liquid, and multiple stages of chemical treatment are often performed. A minute valve (microvalve) that restricts the pressure is required.

Regarding this microvalve, for example, Patent Document 1 discloses that “a device driven by a piezoelectric element, a device driven by an electrode, a device driven by air from an external compressor, and a fluid expansion by heating. Or, any known one can be used, such as those using phase change, "and there are many implementation descriptions.
Further, Patent Document 2 has a description that “in addition to using a screw valve as a valve, various known valves such as an electromagnetic valve can be used”.
Further, Patent Document 3 states that “in order to open the valve, negative pressure is supplied from the driving fluid port to the membrane accommodating chamber through the driving fluid passage, and the membrane in the upper part of the membrane accommodating chamber is moved to the membrane accommodating chamber side (lower side). In the direction) ”.

JP 2004-180555 A ([0034], FIG. 5) JP 2004-205372 A ([0036], FIG. 1) Japanese Unexamined Patent Publication No. 2004-033919 ([0046], FIGS. 4 to 5)

  Since the amount of sample or the like processed by the microchip is very small, it is necessary to prevent slight liquid leakage when the microvalve is closed. However, since a microvalve having a mechanical opening / closing mechanism using a piezo element, a compressor, or the like requires precise processing during manufacturing in order to prevent this leakage, a microchip provided with this microvalve tends to be expensive. . In addition, such a microchip tends to be expensive in that a mechanism for connecting the microvalve to the flow path of the sample or the like is required. In addition, in the example using the expansion and phase change of fluid due to driving and heating by piezo or electrode, an electrode is required to connect the microchip and an external electric circuit. In addition to being expensive, problems such as poor contact are likely to occur.

  The present invention does not require high accuracy at the time of manufacturing, does not require any steps such as electrode manufacturing, and does not require complicated equipment such as a compressor, thereby reducing the price and causing problems such as poor contact. It is an object of the present invention to provide a difficult microvalve and a microchip having one or more microvalves.

The microvalve according to the present invention, which has been made to solve the above problems,
a) a valve member that is arranged to prevent the passage of the liquid and that is in a fluidized state when heat is applied;
b) a heating part that generates an induced current by an alternating magnetic field applied from the outside and heats the valve member by the induced current;
It is characterized by providing.

  In the closed state, the microvalve according to the present invention prevents passage of liquid by a non-flowable valve material. When the valve material is heated by the heat generating portion, the valve material changes to a fluid state and flows out of the microvalve together with the liquid. This opens the microvalve, allowing the liquid to pass through the microvalve.

  As the heat generating portion, one that generates an induced current by applying an alternating magnetic field from the outside and generates heat by the induced current is used. A conductive member can be used for the heat generating portion. The conductive member generates an eddy current when an AC magnetic field is applied from the outside. The conductive member generates Joule heat by the eddy current. Moreover, what consists of a coil and the electrical resistor connected to the coil can also be used for a heat-emitting part. In this case, an induced current is generated by applying an alternating magnetic field to the coil from the outside, and the electric resistor generates heat by the induced current.

  The magnetic field generating means for generating the alternating magnetic field applied to the heat generating portion can be provided not in the microvalve but in a measuring device using the magnetic valve. Of course, magnetic field generating means may be provided in the microvalve itself. Various normal coils can be used as the magnetic field generating means.

  Since the microvalve according to the present invention generates heat from the heat generating portion when an induced current flows, it is not necessary to provide the microvalve with a contact (electrode) for connecting the power source and the heat generating portion. Therefore, high-precision processing is not required at the time of manufacture, and it can be manufactured at a low cost. In addition, since there is no problem such as poor contact during use, the reliability is high. Therefore, a microchip using this microvalve is also inexpensive and highly reliable.

The details of the microvalve of the present invention will be described with reference to FIGS. FIG. 1 shows an example of a microchip using three microvalves according to the present invention.
The microvalves 11a, 11b, and 11c according to the present invention are at the boundary between a plurality of treatment tanks 12 to 14, and are substances that are solid at room temperature but become liquid when heated to several tens of degrees, such as paraffin in the valve chamber, Or, it is filled with a substance (valve material) that is gel-like at normal temperature but sol-forms when heated and does not affect the biochemical analysis in which the microchip is used. The movement of the sample between each tank is blocked.

  In the microchip illustrated in FIG. 1, the detection target sample injected from the sample injection window 10 is freed of impurities and insoluble matters in the first processing tank 12, and then the second processing tank 13 is opened when the microvalve 11 a is opened. After the necessary time elapses, the microvalve 11b is opened to be transferred to the third processing tank 14 where DNA is analyzed by electrophoresis or the like. Thereafter, the micro valve 11c is opened, and the sample is discharged from the third processing tank 14.

  In the microchip illustrated in FIG. 1, when the microvalves 11 a to 11 c are opened according to the sequence determined as described above after injecting a sample from the sample injection window 10, a centrifugal force field, a gravitational field, a pressurization field Then, the sample and the drug are sequentially moved to the adjacent tank by capillary action or the like, and the process is advanced. Large external devices, facilities, and environments are not required, and DNA can be detected easily and in a short time without being an expert. In this embodiment, since it is necessary to make the valve opening control of the microvalve reliable and easy, an electromagnetic induction heater described later is used.

A method for manufacturing a microvalve according to the present invention will be described with reference to FIGS. 2 and 3 showing a cross section XX ′ of a microchip in the vicinity of the microvalve 11a of FIG.
FIG. 2 shows an example of a three-layer structure. A micro-channel using a photolithographic technique or an ink jet on a base material 30 (FIG. (A)) made of a thin plate of plastic such as acrylic resin, polycarbonate resin, silicon resin, glass, ceramic or the like. A wall 31 is pasted (B), and a cover 32 is pasted thereon (C). At this time, instead of attaching the micro flow path wall 31 by photolithography technology, the material constituting the micro flow path wall 31 is applied to the entire surface of the substrate 30, and then the flow path portion is removed by etching or the like. You can also

  FIG. 3 shows an example of a two-layer structure. Manufactured by affixing a cover 32 on a base material 34 (FIG. (A)) in which a flow path portion is formed by resin injection molding using a mold or by a thermal stamp method or hot press method using the same mold. (B). The material of the cover 32 is not limited as long as it is a non-conductive material such as resin or glass, but a transparent material can be used for observing the sample.

  In these manufacturing methods, the valve material is preferably formed in the valve chamber 15 before the cover 32 is attached to the micro flow path wall 31 or the base material 34. At this time, the valve material may be heated to melt or sol the required amount and injected into the valve chamber 15. In addition, it is preferable to inject chemicals such as reagents necessary for each processing layer into the processing layer before the cover 32 is attached to the microchannel wall 31 or the base material 34.

  Further, in FIG. 2 and FIG. 3, for ease of explanation, an example in which the base material 30 having the same size as that of the DNA chip is used is shown. It is more efficient to make a large number of DNA chips at the same time using substrates of the same size, and then cut and separate them.

  Next, an electromagnetic induction heater used for heating to open the microvalve will be described with reference to FIGS. 2 (C) and 3 (B). FIG. 2C and FIG. 3B are examples in which the conductive member 20 is formed on the inner surface of the cover 32. The conductive member 20 is formed by attaching and etching a metal thin film, metal deposition, metal sputtering, metal plating, printing of a conductive paint, or the like. In that case, if the conductive member is a magnetic material or magnetic alloy such as Fe, the energy efficiency is good, but the object can be achieved even if it is a non-magnetic material.

  2 (C) and 3 (B) show an example in which the conductive member 20 is formed on the inner surface of the cover 32, it may be formed on the base material 30 side or both.

Next, the Example regarding the heater used for a microvalve is described using FIGS.
4 to 7 are perspective views enlarging the vicinity of the microvalves 11a to 11c in FIG. 1 and assuming that the inside can be seen using a transparent material for the cover 32. FIG. The conductive member 20 is provided in the vicinity of the valve chamber 15. In addition, the conductive member 20 can have various shapes. For example, the disk-shaped conductive member 20 can be formed on the inner surface of the cover 32 (FIG. 4), or can be formed on the substrate 30 side (FIG. 5). Alternatively, the doughnut-shaped conductive member 20 can be formed on the inner surface of the cover 32 (FIG. 6), or can be formed on the substrate 30 side (FIG. 7).

  One conductive member may be formed for a plurality of microvalves so as to cover a plurality of valve materials of the microvalves. When this microvalve is used, only the microvalve can be opened by applying a magnetic field only in the vicinity of the microvalve to be opened. FIG. 8 shows an example in which a conductive member is formed on the entire surface of the microchip. In FIG. 8, the hatched portion from the upper right to the lower left is the region where the conductive member is formed. Further, the conductive member may be formed not on the entire surface of the microchip but on a part of the region including all the microvalves. In that case, a conductive member may be formed in this region by attaching and etching a metal thin film, metal vapor deposition, metal sputtering, metal plating, printing of a conductive paint, or the like. Thus, by forming only one conductive member for a plurality of microvalves, a microchip can be manufactured more easily than forming an independent conductive member for each microvalve.

  FIG. 9 shows an example in which the electromagnetic induction part and the electric resistor are separately provided. The spiral induction current generating coil 33 is formed on the surface of the cover 32, and the electric resistor 22 is formed on the inner surface of the cover 32. Are connected by vias. FIG. 10 is also an example in which the electromagnetic induction part and the electric resistor are provided separately. In this example, the number of turns of the induction current generating coil 33 ′ is set to 1, so that it is formed on the inner surface of the cover 32 together with the electric resistor 22. is there.

  In the case where the electromagnetic induction part and the electric resistor are separated as in these two examples, since the Joule heat generated by the induced current is proportional to the resistance value, the electromagnetic induction part has a resistance value that is higher than the resistance value of the electric resistor. It is desirable that the resistance value be a fraction or less or a few tenths or less.

  FIG. 11 is an example of a contact point type heat generating portion shown for comparison with the electromagnetic induction method according to the present invention. In this example, the electrical resistor 22 is formed on the inner surface of the cover 32, the contacts 21a and 21b for supplying power to the electrical resistor 22 are formed on the surface of the cover 32, and the gaps are connected by vias. Compared to this example, a microchip manufacturing process is likely to be complicated, such as requiring a via and further requiring anti-oxidation plating at the contact portion. Furthermore, since a contact is required to connect the electronic circuit and the electric resistor during heating, troubles such as poor contact are likely to occur.

  Although FIGS. 4 to 10 show two examples of the shape of the valve chamber, a round shape and a square shape, the shape and size of the valve material do not flow out due to the pressure of a centrifugal force field or the like for transferring a sample or the like. Then, the shape and size can be determined freely.

  FIG. 12 shows an example of an AC magnetic field generating unit for electromagnetic induction heating, in which a magnetic field generating coil 41 is wound around a cylindrical core 40a. An AC magnetic field is generated by applying an AC current of 20 KHz to several hundreds KHz from the AC power source 42 to the magnetic field generating coil 41, and when the magnetic field passes through the above-described conductive member or the induction current generating coil 33, the conductive member 20. Alternatively, an alternating current is generated in the induction current generating coil 33. Due to this current, Joule heat is generated in the resistance of the conductive member 20. In FIG. 12, the cylindrical core 40a is shown as an example, but the shape of the core 40a can be arbitrarily determined, such as a prism.

  FIG. 13 shows an example of an AC magnetic field generator using a core 40b having a shape generally called a pot core. The function of this AC magnetic field generation unit is the same as that of FIG. 12, but energy can be supplied more efficiently than that of FIG.

  FIG. 14 shows an example of an AC magnetic field generation unit in which a missing portion 43 is provided in a part of a core 40c generally called a toroidal core. The conductive member 20 or the induction current generating coil 33 is disposed in the defective portion 43. This AC magnetic field generator is an example that can supply energy more efficiently than the two examples described above. Here, the core 40c having a circular cross section is shown as an example, but the shape of the core 40c can be arbitrarily determined.

Sectional drawing which shows the example which provided the microvalve of this invention in the microchip which has a three-stage structure. Sectional drawing which shows an example of the manufacturing method of the microvalve of this invention. Sectional drawing which shows the other example of the manufacturing method of the microvalve of this invention. The perspective view which shows the example which formed the disk-shaped electroconductive member in the inner surface of the cover. The perspective view which shows the example which formed the disk shaped electroconductive member in the base material side. The perspective view which shows the example which formed the doughnut-shaped electroconductive member in the inner surface of the cover. The perspective view which shows the example which formed the doughnut-shaped electroconductive member in the base material side. Sectional drawing which shows the example which formed the electroconductive member in the whole surface of the microchip. The perspective view which shows the example which formed the coil of multiple turns separately from the electrical resistor. The perspective view which shows the example which formed the coil of 1 turn separately from the electrical resistor. The perspective view which shows the example using the nonelectromagnetic induction heating system which is a comparative example. The perspective view which shows the example of the alternating current magnetic field generation part using a columnar core and a coil. The perspective view which shows the example of the alternating current magnetic field generation part using a pot core and a coil. The perspective view which shows the example of the alternating current magnetic field generation part using a toroidal core and a coil.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Sample injection | pouring window 11a, 11b, 11c ... Micro valve 12 ... 1st processing tank 13 ... 2nd processing tank 14 ... 3rd processing tank 15 ... Valve chamber 20 ... Conductive member 21a, 21b ... Contact 22 ... Electric resistor 30, 34 ... Base material 31 ... Micro flow path wall 32 ... Cover 33 ... Inductive current generating coil 40a ... Columnar core 40b ... Pot core core 40c ... Toroidal core 41 ... Magnetic field generating coil 42 ... AC power supply 43 ... Defect portion

Claims (6)

a) a valve member that is arranged to prevent the passage of the liquid and that is in a fluidized state when heat is applied;
b) a heating part that generates an induced current by an alternating magnetic field applied from the outside and heats the valve member by the induced current;
A micro valve characterized by comprising:   2. The microvalve according to claim 1, wherein the heat generating portion is a conductive member that generates eddy current by the alternating magnetic field and generates Joule heat by the eddy current.   3. The microvalve according to claim 2, wherein one conductive member is formed so as to cover a plurality of valve members.   2. The microvalve according to claim 1, wherein the heat generating part comprises a coil and an electric resistor connected to the coil.   The microvalve according to any one of claims 1 to 4, further comprising magnetic field generation means for generating the alternating magnetic field.   A microchip comprising the microvalve according to claim 1 in a liquid flow path.

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