JP2016053397A - Liquid feed control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solution feeding control device that securely enables a solution advancing in a minute flow passage to rest and that enables shortening of the length in a flow passage direction of a valve and passing time of the solution on the valve when a potential is applied.SOLUTION: An inlet portion 14, an outlet portion 15 and a flow passage portion 16 are formed in a minute flow passage structure 2 of a solution feeding control device 1. A valve 19 arranged in the flow passage portion 16 includes: a hydrophilic platinum electrode 26 formed on part of the bottom surface of the flow passage portion 16; and a hydrophobic self-assembled monolayer 27 formed on the platinum electrode 26. The solution supplied from the inlet portion 14 is made to rest by the self-assembled monolayer 27 and a negative potential is applied to the platinum electrode 26 to remove the self-assembled monolayer 27, so as to expose the surface of the platinum electrode 26 and enable the solution to pass on the platinum electrode 26.SELECTED DRAWING: Figure 1

Description

  This invention is used in chemical, biological, medical, material engineering, electrochemical engineering, semiconductor engineering, electronics, microchemical analysis, nanotechnology, and other research fields to control and feed a small amount of fluid. Relates to the device.

  In recent years, chemical reactions, cell culture, separation detection, etc. have been performed on a microchemical analysis system (μTAS) that performs chemical reactions on a chip, or a chip that has a small groove or indentation on a small substrate such as glass. Research on a lab-on-a-chip (lab on a chip) that integrates a lab process (lab process) is being actively conducted. As described above, this intends to miniaturize a conventional analysis system or chemical laboratory to the extent that it can be put on a palm.

  By miniaturizing the analysis system and the like, effects such as (1) a small amount of sample and reagent, (2) high-speed response, and (3) high throughput are realized. The applications of these miniaturized analysis systems (hereinafter referred to as microsystems) are various, but on such microsystems, it is necessary to control and send a small amount of fluid. In particular, realization of a liquid delivery device in which all elements are integrated is expected.

  Mechanical micropumps and microvalves have already been studied since the 1980s as devices for controlling and feeding a small amount of fluid. However, the construction of an advanced liquid delivery device in which these are integrated has been hardly successful so far. This seems to be due to the fact that it is difficult to achieve a high degree of structural integration.

  For this reason, when it is desired to introduce a minute fluid (for example, a solution) into a minute flow path and send it, a commercially available micro syringe pump is often used. Of course, this may be sufficient depending on the purpose such as basic research, but if a microsyringe pump is used, portability is impaired. Also, the micro syringe pump is very expensive.

  Therefore, as a means for feeding liquid in a relatively complicated microchannel, there is a liquid feeding mechanism that uses electroosmotic flow. The electroosmotic flow is a movement phenomenon that a solution in contact with a glass tube or the like exhibits under a high voltage, and is usually generated by analysis using capillary electrophoresis with DNA or the like as a measurement target.

  In capillary electrophoresis, an electrode is inserted into a solution reservoir containing particles such as DNA formed at the end of a micro flow channel formed mainly in quartz glass, and a high voltage of several hundred volts to several thousand volts is applied. This is a phenomenon of applying and moving the solution in the microchannel. A liquid feeding mechanism using electroosmotic flow (hereinafter referred to as an electroosmotic pump) is structurally very simple and can be easily fed through a complicated flow channel network.

  By the way, regarding the electroosmotic flow, for example, the following Patent Document 1 discloses a sample injection device of a capillary electrophoresis apparatus that suppresses electrophoresis and injects a sample into the capillary by the electroosmotic flow (Patent Document). 1).

  Conventional micropumps and microvalves have a problem that drive voltage and power consumption increase. Specifically, for example, even if the drive voltage is small, it is several tens of volts, and accordingly, power consumption is also a problem. Furthermore, the smaller the flow path, the greater the influence of interfacial tension and the like, and depending on the flow path structure and operating principle, it becomes difficult to perform smooth liquid feeding.

  For this reason, especially when a conventional mechanical pump such as a micropump or a microvalve is used, integration on a chip has been a problem. Similarly, the electroosmotic pump also has a problem because a high voltage is required, and the power consumption becomes too large to be ignored.

  In order to solve the above-described conventional problems, the present inventor has proposed a liquid feeding device having a structure in which the wettability of a gold electrode formed on the bottom of a microchannel is changed and a solution is allowed to pass (see Patent Document 2).

Japanese Patent Laid-Open No. 5-142198 (first page, FIG. 1) Japanese Patent No. 4632300

  In the invention described in the cited document 2, it has a simple structure, consumes little electric power, can perform smooth liquid feeding even if the flow path is miniaturized, and in addition, sequentially inject a plurality of fluids, It was possible to realize a highly integrated micro liquid delivery system that can efficiently perform a series of liquid delivery controls including discharge.

  However, in the invention described in the cited document 2, in order to ensure that the solution reaching the valve is stopped there, the flow path of the valve section must be narrowed and the electrode must be elongated in the flow path direction. However, on the contrary, there is a problem that the response time (the time for the solution to pass through the valve after applying the potential) becomes longer.

  The object of the present invention is to solve the above-mentioned conventional problems, the solution traveling in the micro flow path can be surely stopped, the length of the valve in the flow path direction can be shortened, and the potential can be applied. It is an object of the present invention to realize a liquid feeding control device that can shorten the passage time of the solution on the valve at the time.

  In order to solve the above problems, the present invention has an inlet portion, an outlet portion, and a passage portion formed in a microchannel structure, and a valve is provided in the middle of the passage portion, and is supplied from the inlet portion. The liquid solution is fed by capillary action in the flow path section and is stopped by the valve, or is passed through the valve to the outlet section. Provided with a hydrophilic electrode formed on the bottom surface of the part and a hydrophobic self-assembled monolayer formed on the electrode. When no negative potential is applied to the electrode, the electrode is supplied from the inlet. The solution is placed in a state where the valve that is stationary by the hydrophobic self-assembled monolayer is closed, and by applying a negative potential to the electrode, the self-assembled monolayer is removed, and the surface of the electrode is removed. By exposing, the solution supplied from the inlet can pass over the electrode. Providing liquid feed control device comprising a structure for a state that opening the valve.

  In the microchannel structure, a resin plate is laminated on a glass substrate, and a recess that forms an inlet portion, an outlet portion, and a channel portion is formed on the lower surface of the resin plate that contacts the upper surface of the glass substrate. Is preferred.

  It is preferable that a valve is formed at each of a plurality of locations in one flow path portion.

  It is preferable that a valve is formed in each of a plurality of flow path portions formed so as to extend radially from the inlet portion.

  Preferably, the positive electrode of the constant voltage power supply device can be electrically connected to the solution at the inlet, and the negative electrode of the constant voltage power supply device can be connected to the electrode of the valve.

  It is preferable that a reference electrode that can be electrically connected to the positive electrode of the constant voltage power supply device is provided at the inlet.

  The resin plate laminated on the glass substrate of the microchannel structure is preferably made of polydimethylsiloxane.

  According to the present invention, the hydrophobic self-assembled monolayer can reliably stop the solution traveling in the micro flow path, and the length of the valve in the flow path direction can be shortened. The effect that the transit time of the upper solution can be shortened is also produced.

(A) is a figure which shows the whole structure of Example 1 of the liquid feeding control apparatus based on this invention, (b) is a figure which shows the BB vertical cross section of (a). (A) is a figure which shows some structures of the platinum electrode of the said Example 1, (b), (c) is a figure explaining the effect | action of the said Example 1. FIG. (A)-(c) is a figure explaining the effect | action of the said Example 1. FIG. In the said Example 1, it is a figure which shows formation and reductive desorption of the self-organization monomolecular film | membrane on the platinum electrode of alkanethiol. (A), (b) is a figure explaining the structure and effect | action of Example 2 of the liquid feeding control apparatus which concerns on this invention. (A), (b) It is a figure explaining the effect | action of Example 2 of the liquid feeding control apparatus which concerns on this invention. It is a figure explaining the structure of Example 3 of the liquid feeding control apparatus which concerns on this invention. (A), (b) It is a figure explaining the effect | action of Example 3 of the liquid feeding control apparatus based on this invention, and a reference electrode, a potentiostat, a switch, etc. were abbreviate | omitted.

  EMBODIMENT OF THE INVENTION The form for implementing the liquid feeding control apparatus which concerns on this invention is demonstrated below with reference to drawings based on an Example.

(Example 1)
Embodiment 1 of a liquid feeding control device according to the present invention will be described with reference to FIGS. FIG. 1A is a diagram showing the overall configuration of a first embodiment of the liquid feeding control device according to the present invention and showing the configuration of a basic liquid feeding control device. The liquid feeding control device 1 has a micro flow channel structure 2.

  The microchannel structure 2 is formed by laminating a resin plate 4 on a glass substrate 3 as shown in FIG. The resin plate 4 is formed of a resin material such as hydrophobic polydimethylsiloxane (PDMS). On the lower surface 8 of the resin plate 4 that comes into contact with the upper surface 7 of the glass substrate 3, a concave portion 10 that forms a microchannel 9 is formed. In addition, it replaced with the glass substrate 3 and the resin board 4, and what was formed with materials other than glass and polydimethylsiloxane may be used.

  The microchannel 9 is composed of a recess 10 and a channel space surrounded by the upper surface 7 of the glass substrate 3 corresponding to the recess 10. The microchannel 9 of the first embodiment includes an inlet portion 14, an outlet portion 15, and a channel portion 16. The solution can flow in the channel portion 16 by capillary action. A valve 19 is provided in the middle of the flow path portion 16. The present invention is characterized by the structure of the valve 19 and will be described later in detail.

  The solution 20 whose liquid feeding is controlled by the liquid feeding control device 1 is supplied to the inlet 14. The inlet portion 14 functions as a liquid reservoir, and the solution 20 is further supplied from the inlet portion 14 into the flow path portion 16. A reference electrode 21 that is always in contact with the supplied solution 20 is attached to the bottom of the inlet portion 14. The reference electrode 21 is formed of an electrode material such as silver (Ag) / silver chloride (AgCl), and is led out from the inlet portion 14 to the side surface side of the microchannel structure 2 as shown in FIG.

  When the valve 19 is open in the flow path section 16, the solution 20 supplied into the flow path section 16 passes through the valve 19 and further flows in the flow path section 16 and supplies the solution 20 from the outlet section 15. The solution is sent to the intended user.

  The valve 19 is provided in a part of the channel portion 16 and has a hydrophilic property formed in a thin film on the glass substrate 3 as shown in FIGS. 1B and 3B. A platinum electrode 26 and a hydrophobic self-assembled monolayer (SAM) 27 formed on the platinum electrode 26.

  As shown in FIG. 1A, the platinum electrode 26 includes a connection portion 28 that extends laterally within the microchannel structure 2, a contact pad 29 disposed outside the microchannel structure 2, It is integrally formed from. In the present embodiment, the platinum electrode 26 is used. However, instead of the platinum electrode 26, an electrode formed of a metal such as gold, silver, copper, or palladium may be used.

  In the liquid feeding control device 1 according to the first embodiment, a potentiostat 33 used as a constant voltage power supply device is attached. The negative side of the potentiostat 33 is connected to the contact pad 29 via the switch (SW) 34, and the positive side is connected to the reference electrode 21.

  The cross-sectional area of the flow path section 16 (cross-sectional area perpendicular to the flow) is made different depending on the supply amount of the supplied solution.

  FIG. 2A shows a plurality of platinum electrodes 26-1 to 26-5 formed integrally with the connection portion 28 and the contact pad 29. The platinum electrodes 26-1 to 26-5 are each formed to have a dimension L in the flow path direction in which numerical values are described below.

Although the self-assembled monolayer 27 itself is already known, a hydrophobic organic molecule reactive with the platinum electrode 26 is used as the self-assembled monolayer 27. The self-assembled monolayer 27 is formed on the platinum electrode 26 in advance before use. The self-assembled monolayer 27 may generally be an alkanethiol, but 1-hexanethiol (CH ₃ (CH ₂ ) ₅ SH) having a short alkyl chain length is particularly preferable.

  The self-assembled monolayer 27 formed on the platinum electrode 26 has hydrophobicity, and as shown in FIG. 3 (a), the organic molecules 37 are densely assembled by the interaction between them, and The orientation is aligned.

  In this manner, the organic molecules 37 are densely assembled on the surface of the platinum electrode 26, whereby the self-assembled monomolecular film 27 is formed (see FIG. 4). In the state where the self-assembled monolayer 27 is present, the solution 20 that has progressed due to the capillary phenomenon is stopped before the valve 19, and as shown in FIG. 2A, the valve 19 is closed.

  FIG. 4 shows a state in which alkanethiol (R-SH) is densely assembled on the electrode 26 and the self-assembled monolayer 27 is formed (see the right side of FIG. 4), and a negative potential is applied to the platinum electrode 26. It is a figure which shows the change of the state (refer left side of FIG. 4) in which alkanethiol is reduced-desorbed from the electrode 26 by applying.

(Function)
The operation of the liquid feeding control apparatus 1 according to the first embodiment having the above-described configuration will be described with reference to FIGS. 2B and 2C and FIGS. 3A to 3C. First, the solution 20 to be sent is supplied from the inlet portion 14 into the flow path portion 16.

  In the state where the switch 34 of the potentiostat 33 is opened and no negative potential is applied to the platinum electrode 26, the potentiostat 33 is formed on the platinum electrode 26 in the valve 19 as shown in FIGS. 2 (b) and 3 (a). Further, the surface of the platinum electrode 26 is difficult to wet with the solution 20 because of the hydrophobic self-assembled monolayer 27. Therefore, the solution 20 does not pass through the valve 19 but stops before it, and the valve 19 is closed.

  When the switch 34 is closed and the negative electrode side of the potentiostat 33 is connected to the contact pad 29, the circuit is closed by the potentiostat 33, the reference electrode 21, the solution 20, the platinum electrode 26, the connection portion 28, and the contact pad 29. Is applied.

  When a negative potential is applied to the platinum electrode 26 by the potentiostat 33, the self-assembled monolayer 27 starts to be reduced and desorbed as shown in FIG. 3B (see FIG. 4). As a result, hydrophilic platinum The surface of the electrode 26 is exposed. In this state, the contact angle between the droplet of the solution 20 and the surface of the platinum electrode 26 becomes small, and a hydrophilic state is obtained.

  As shown in FIG. 3C, the solution 20 advances on the surface of the hydrophilic platinum electrode 26 while peeling the self-assembled monolayer 27, and the valve 19 is in an open state. Then, as shown in FIG. 2C, the solution 20 passes through the valve 19 and is sent to the outlet portion 15. In addition, the liquid feeding control apparatus 1 of the present invention assumes a single use application from the closed state to the open state in which the self-assembled monolayer 27 is detached and opened as described above from the state in which the valve 19 is closed. doing.

  According to the liquid feeding control device 1 of the present invention, the hydrophobic self-assembled monolayer 27 is formed on the platinum electrode 26 and the solution 20 flowing in the microchannel 9 can be surely stopped by capillary action. it can.

  Moreover, according to the liquid feeding control device 1 of the present invention, the self-assembled monolayer 27 is removed instead of changing the wettability of the platinum electrode 26 itself as in the invention described in Patent Document 2. By exposing the surface of the hydrophilic platinum electrode 26, the wettability can be increased and the solution 20 can be quickly moved on the surface of the platinum electrode 26.

  When the liquid feeding control device 1 of the present invention is used, the hydrophobic self-assembled monomolecular film 27 has a large effect of reliably stopping the solution 20 traveling in the microchannel 9. The length dimension L in the flow path direction of the valve 19 can be shortened. As a result, the length of the valve 19 in the flow path direction can also be shortened and the size can be reduced. can do.

  The liquid feeding control device 1 of the first embodiment described above shows the basic configuration of the liquid feeding control device of the present invention. In the liquid feeding control device that is actually used, 1 of the micro-channel structure 2 is used. Alternatively, one or a plurality of valves are formed as appropriate at appropriate locations in the flow path portion formed in a plurality. A configuration example in which a plurality of valves are appropriately provided in the flow path portion will be described below in the second and third embodiments.

(Example 2)
Embodiment 2 of the liquid feeding control device according to the present invention will be described with reference to FIGS. As shown in FIG. 5A, the liquid feeding control device 41 according to the second embodiment includes a micro flow channel structure 42. The microchannel structure 42 includes a microchannel 44 including an inlet portion 14, a meandering channel portion 43, and an outlet portion 15.

  Four valves, first to fourth valves 46 to 49, are arranged in the middle of the meandering flow path portion 43 from the upstream side to the downstream side. The first to fourth valves 46 to 49 of the second embodiment have the same configuration as the valve 19 of the first embodiment.

  A reference electrode 21 is provided at the inlet portion 14 as in the first embodiment. In addition, a potentiostat 33 is attached, the negative electrode side of the potentiostat 33 is connected to the contact pads 29 of the first to fourth valves 46 to 49, and the positive electrode side is connected to the reference electrode 21. Switches SW1 to SW4 are provided in the connection between the potentiostat 33 and the contact pads 29, respectively, and can be selectively opened and closed.

  In the liquid feeding control device 41 of the second embodiment, as shown in FIG. 5B to FIG. 6A and FIG. The liquid can be fed toward the outlet portion 15 while still and passing through the four valves 46 to 49 sequentially.

  In the state shown in FIG. 5B, the first valve 46 closest to the inlet portion 14 is closed, and the solution 20 is stationary before the first valve 46.

  In the state shown in FIG. 6A, the first valve 46 is open and the second valve 47 is closed. The solution 20 passes through the first valve 46 and is stationary before the second valve 47.

  In the state shown in FIG. 6B, the first and second valves 46 and 47 are open, and the third valve 48 is closed. The solution 20 passes through the first and second valves 46 and 47, and is stationary before the third valve 48.

  According to the liquid feeding control device 41 of Example 2 having such a configuration, the solution 20 can pass by opening each of the first to fourth valves 46 to 49, and the outlet portion as described above by capillary action. The liquid can be fed toward the direction 15.

(Example 3)
A third embodiment of the liquid feeding control device according to the present invention will be described with reference to FIGS. As shown in FIG. 7, the liquid feeding control device 61 of the third embodiment has a micro flow channel structure 62. In the microchannel structure 62, a microchannel 63 including an inlet portion 14, a channel portion, and an outlet portion 80 is formed. The flow path part of Example 3 is composed of eight flow path parts of first to eighth flow path parts 66 to 73 formed so as to extend radially from the inlet part 14.

  A reference electrode 21 is provided at the inlet 14. First to eighth outlet portions 78 to 85 are formed at the ends of the first to eighth flow passage portions 66 to 73. In addition, first to eighth valves 89 to 96 are provided in the middle of the first to eighth flow path portions 66 to 73, respectively. The first to eighth valves 89 to 96 have the same configuration as the valve 19 of the first embodiment.

  The liquid supply control device 61 of the third embodiment is also provided with a potentiostat 33. Similarly to the configuration of the liquid supply control device 41 of the second embodiment, the negative electrode side of the potentiostat 33 is the first to eighth valves 89. -96 are connected to the contact pads 29, the positive electrode side is connected to the reference electrode 21, and switches SW1 to SW8 are provided in the connection between the potentiostat 33 and the contact pads 22, respectively. It can be opened and closed.

  According to the liquid feeding control device of Example 3 having such a configuration, as shown in FIG. 8A, all of the first to eighth valves 89 to 96 are always closed, As shown in FIG. 8B, when the first valve 89 and the sixth valve 94 are opened, the respective outlet portions 78 and outlet portions are passed through the first flow path portion 66 and the sixth flow path portion 71, respectively. Up to 83, the solution 20 can be fed by capillary action.

  The liquid feeding control device 61 of the third embodiment selectively feeds the same solution 20 from one inlet 14 to any one of the first to eighth outlets 78 to 85, and uses a plurality of usage destinations. Suitable for supplying to any of the above.

  As mentioned above, although the form for implementing the liquid feeding control apparatus which concerns on this invention was demonstrated based on the Example, this invention is not limited to such an Example, The technical matter as described in a claim It goes without saying that there are various embodiments within the scope of the above.

  The liquid transfer control device according to the present invention is based on portable microanalytical instruments in research fields such as chemistry, biology, medicine, material engineering, electrochemical engineering, semiconductor engineering, electronics, microchemical analysis, and nanotechnology. It can be used as a liquid feed control device that feeds liquid by controlling a small amount of fluid.

DESCRIPTION OF SYMBOLS 1 Control liquid feeder 2 Microchannel structure 3 Glass substrate 4 Resin plate 7 Upper surface of glass substrate 8 Lower surface of resin plate
DESCRIPTION OF SYMBOLS 9 Microchannel 10 Recessed part formed on the lower surface of the resin plate constituting the microchannel 14 Inlet portion 15 Outlet portion 16 Channel portion 19 Valve 20 Solution 21 Reference electrode 26 Platinum electrode 27 Self-organized monolayer 28 Connection of platinum electrode Part 29 Contact pad of platinum electrode 33 Potentiostat 34 Switch between potentiostat and contact pad 37 Organic molecule
DESCRIPTION OF SYMBOLS 41 Liquid supply control apparatus 42 Micro flow path structure 43 Serpentine-shaped flow path part 44 Micro flow path 46-49 1st-4th valve 61 Liquid supply control apparatus 62 Micro flow path structure 63 Micro flow path 66-73 First to eighth flow path portions 78 to 85 First to eighth outlet portions 89 to 96 First to eighth valves

Claims (7)

The microchannel structure is formed with an inlet portion, an outlet portion, and a channel portion, and a valve is provided in the middle of the channel portion. A liquid feed control device that is fed and stopped by a valve, or passed through the valve to the outlet,
The valve includes a hydrophilic electrode formed on a part of the bottom surface of the flow path portion, and a hydrophobic self-assembled monolayer formed on the electrode,
When a negative potential is not applied to the electrode, the solution supplied from the inlet is in a state where the valve that is stationary by the hydrophobic self-assembled monolayer is closed,
A valve that allows the solution supplied from the inlet to pass over the electrode by removing the self-assembled monolayer by applying a negative potential to the electrode and exposing the surface of the electrode. A liquid feeding control device characterized by being configured to be opened.   In the microchannel structure, a resin plate is laminated on a glass substrate, and a recess that forms an inlet portion, an outlet portion, and a channel portion is formed on the lower surface of the resin plate that contacts the upper surface of the glass substrate. The liquid feeding control device according to claim 1.   The liquid feeding control device according to claim 1, wherein valves are respectively formed at a plurality of locations of one flow path portion.   The liquid feeding control device according to any one of claims 1 to 3, wherein a valve is formed in each of the plurality of flow passage portions formed to extend radially from the inlet portion.   The positive electrode of a constant voltage power supply device can be electrically connected to the solution at the inlet, and the negative electrode of the constant voltage power supply device can be connected to the electrode of the valve. The liquid feeding control device according to claim 1.   The liquid feeding control device according to claim 1, wherein a reference electrode that can be electrically connected to a positive electrode of the constant voltage power supply device is provided at the inlet portion.   The liquid feeding control device according to any one of claims 1 to 6, wherein the resin plate laminated on the glass substrate of the microchannel structure is formed of polydimethylsiloxane.