JP2007177769A - Micropump device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a micropump device capable of stably operating over a long period by resolving failure relating to generation of oxygen gas by electrolysis and to working fluid, such as clogging by condensation of a particulate. <P>SOLUTION: The micropump is provided with a porous thin membrane 22 which is disposed in a flow passage, a pair of electrodes 24, 26 which are disposed on both sides of the porous thin membrane, a means of supplying the working fluid Lw into the flow passage and a direct-current power supply 34 which impresses direct-current voltage between the pair of electrodes. The pair of electrodes 24, 26 are of a tabular shape formed with a plurality of through holes 27. The micropump causes flow of the working fluid Lw via the porous thin membrane 22 by impressing the direct-current voltage between the pair of electrodes 24, 26. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a micropump device capable of precisely controlling the flow rate of a liquid.

  For example, in the case where a solution containing blood, DNA, cells, or the like is poured into a microchannel and an object is magnified and observed with a microscope, if the flow rate fluctuates or pulsates, the image is preliminarily observed and accurate observation cannot be performed. For this reason, development of a micropump device capable of controlling a minute flow rate without pulsation or fluctuation has been eagerly desired.

  As such a micropump device, the inventors previously developed a device using a completely new principle (Patent Document 1). As shown in FIG. 11, a porous thin film 84 is disposed in a jacket 82 that constitutes a flow path of a working fluid 80 such as an electrolyte aqueous solution or a colloidal solution, and a pair of porous thin films 84 are disposed on both sides of the porous thin film 84. The electrodes 86 and 88 are disposed, and a DC voltage is applied between the pair of electrodes 86 and 88 so that the working fluid passes through the porous thin film 84 to generate a minute flow rate.

  However, in the conventional technology as described above, a ring-shaped member is used as an electrode, and the voltage distribution is reduced in the central portion of the porous thin film, and the flow rate is lower than that in the peripheral portion. Further, when an aqueous electrolyte solution is used as the working fluid, electrolysis is likely to occur, and oxygen may be generated at the cathode, resulting in malfunction. On the other hand, when a colloidal solution is used as the working fluid, there is also a problem that fine particles condense and clog the porous membrane.

  Further, in order to configure a micropump using such a principle, in Patent Document 1, a buffer solution is introduced between the working fluid and the discharge solution, so that the buffer solution can alter or contaminate the discharge solution. In some cases, the hydraulic fluid may be mixed with the discharged liquid. Furthermore, the three liquids must be handled at the time of starting the micro pump, replenishing the discharge liquid, maintenance, etc., and the work is complicated, or a curved pipe part for holding the buffer liquid is formed. In addition, there are problems such as complicated structure and difficulty in incorporation into a microchip.

International Publication No. 2005/052379

  The present invention has been made in view of the above circumstances, and eliminates problems associated with hydraulic fluids such as generation of oxygen gas due to electrolysis and clogging due to condensation of fine particles, and can operate stably over a long period of time. An object is to provide a pump device.

  Another object of the present invention is to provide a highly practical micropump device that reduces the risk of contamination of the discharge liquid and is easy to perform operations such as start-up, discharge liquid replenishment, and maintenance. It is.

  In order to achieve the object, the micropump device according to claim 1, a porous thin film disposed in the flow path, a pair of electrodes disposed on both sides of the porous thin film, and the flow path Means for supplying a hydraulic fluid and a DC power source for applying a DC voltage between the pair of electrodes, wherein the pair of electrodes has a plate shape in which a plurality of through holes are formed, and between the pair of electrodes The flow of the working fluid through the porous thin film is generated by applying a direct current voltage to the liquid crystal.

  In the first aspect of the invention, the pair of electrodes has a plate shape in which a plurality of through holes are formed, and a uniform voltage distribution is applied to the entire surface of the porous thin film by applying a DC voltage between the pair of electrodes. Is formed. Therefore, a minute flow of the working fluid is formed on the entire surface of the porous thin film, and an efficient pumping operation is performed.

A micropump device according to a second aspect is the invention according to the first aspect, wherein the hydraulic fluid is a solution treated so as not to cause electrolysis.
According to a third aspect of the present invention, in the invention according to the second aspect, the working fluid is a colloidal solution in which fine particles are dispersed in a liquid.

  A micropump device according to a fourth aspect is the micropump device according to the second aspect, wherein the hydraulic fluid is ion-exchanged water or distilled water.

  In the invention described in claim 4, since the working fluid is ion-exchanged water or distilled water, electrolysis and fine particle condensation do not occur when a DC voltage is applied between the pair of electrodes. Therefore, the malfunction due to these does not occur, and the stable operation is performed for a long time. Note that the operating principle when the working fluid is ion-exchanged water is considered to be different from that in Patent Document 1, and details are under investigation.

A micropump device according to a fifth aspect is the invention according to any one of the first to fourth aspects, wherein a separation membrane having flexibility is installed on the downstream side of the porous thin film. The discharge liquid is accommodated in the discharge chamber provided on the other side, and the driving force of the working liquid is transmitted to the discharge liquid through the separation membrane.
In the invention described in claim 3, since the working fluid and the discharge liquid are separated by the separation membrane, the discharge liquid is prevented from being contaminated, and operations such as replenishment of each liquid are performed independently. Work can be reduced.

According to the first aspect of the present invention, a more efficient micropump device is provided.
According to invention of Claim 2, the micropump apparatus which operate | moves stably over a long term is provided.
According to the third aspect of the present invention, there is provided a highly practical micropump device that reduces the risk of contamination of the discharge liquid and is easy to perform operations such as start-up, discharge liquid replenishment, and maintenance. Offer is provided.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram schematically showing a micropump device according to one embodiment of the present invention. This has an operation part 1 that forms a minute flow of the hydraulic fluid, and a transmission part 2 that transmits the driving force of the hydraulic fluid to the discharge liquid.

  In the central part of the working container 1a constituting the working part 1, a porous thin film 22 is arranged so as to bisect the internal space (hereinafter, the left side is called the upstream chamber 28 and the right side is the downstream chamber 30 in the figure), A pair of electrodes 24 and 26 are arranged on both sides of the porous thin film 22. The space on both sides of the porous thin film 22 is filled with the working liquid Lw. The working liquid Lw is a liquid in which fine particles having a particle size of 0.01 μm to 0.5 μm having a property of being charged in a liquid, for example, a colloidal solution in which fine particles are separated in a solution, an aqueous electrolyte solution Alternatively, ion exchange water (distilled water) or the like can be used.

  As an example, the porous thin film 22 is made of nickel having a thickness of 11 μm, and 55600 holes having a diameter of about 5 μm are regularly provided in a circular region having a diameter of 8 mm. The porous pore diameter is preferably in the range of 1 μm to 100 μm. As the porous thin film 22, not only a metal but also an appropriate material such as a resin or a ceramic can be used.

  As shown in FIG. 2 (a), the electrodes 24 and 26 are formed by forming one circular hole 27 at the center of the disk and eight circumferential holes at equal intervals in the circumferential direction. In this embodiment, the center has a diameter of 2.0 mm and the periphery has a diameter of 1.5 mm. The size, shape, and number of the holes 27 can be determined as appropriate. If the diameter is too small, it will cause resistance to liquid flow, and it will be difficult to vent the initial stage. FIG. 2B shows the shape of a conventional ring-shaped electrode, and a hole having a diameter of 5 mm is formed at the center.

  The distance between each electrode 24, 26 and the porous thin film 22 is preferably in the range of about 1 mm to 1 cm. The pair of electrodes 24 and 26 are connected to a DC power supply 34 via a changeover switch 32. The DC power supply 34 is a power supply for supplying a DC voltage of about 100 V or less to the pair of electrodes 24 and 26, and a battery can be used. Alternatively, the DC power supply 34 may be a power supply device that obtains a DC power supply from an AC power supply via a converter. Further, it is assumed that voltage adjusting means such as a variable resistor is provided.

  This micropump device basically operates with the changeover switch 32 with the upper electrode 24 as + and the lower electrode 26 as-. That is, the fine particles that behave as if they are positively charged in the liquid are pushed out from the micropores of the porous thin film 22, and are sent from the upstream chamber 28 to the downstream chamber 30. If the conditions of the porous thin film 22 and the hydraulic fluid Lw are the same, the flow rate is controlled by the voltage between the electrodes. Of course, the changeover switch 32 can reverse the voltage and reverse the flow.

  The transmission part 2 is provided with a separation membrane 48 in the center of the transmission container 2a. The left side of the separation membrane 48 is the hydraulic fluid space 4 that communicates with the downstream chamber 30 via the hydraulic fluid pipe 3, and the right side is the ejection fluid space 5 that accommodates the ejection fluid Lh. The discharge liquid space 5 communicates with a discharge liquid supply device such as a microchip via a discharge pipe 6.

  The separation membrane 48 is a flexible member made of resin, various rubbers, etc., and is not flat but has a shape in which the center swells. Although it is made of polyethylene in this embodiment, it does not react with the hydraulic fluid Lw or the discharge fluid Lh, and it only needs to have a strength that does not compress or expand with respect to the pressure of about the head h. In this embodiment, the separation membrane 48 is a dome shape having an elliptical cross section, but it may be a circular shape, a cone shape, or an indeterminate shape, and the volume of the protruding portion can be changed by changing the shape. I just need it.

Example 1
An experiment for comparing the flow rates was performed using the two electrodes 24 and 26 shown in FIGS. The working fluid was a colloidal solution containing 0.1% silica fine particles, and a 2 μm polycarbonate membrane was used as the porous thin film 22. The applied voltage is 10V. The results are shown in FIG.
From this figure, it can be seen that the multi-hole electrodes 24 and 26 of the present invention can obtain a flow rate about twice that of the conventional ring-shaped electrode.

(Example 2)
Fig.4 (a) is the result of the Example at the time of using ion-exchange water as the hydraulic fluid Lw. The electrode has the shape shown in FIG. 2A, and a 2 μm polycarbonate film was used as the porous thin film 22. The applied voltage is 10V. FIG. 4B is a comparative example using a colloidal solution containing 0.01% silica fine particles as the working fluid. The applied voltage is 10 V, and a 2 μm polycarbonate film is used as the porous thin film 22. The same as in the case of a).

  When the ion exchange water shown in FIG. 4 (a) is used, the flow rate is about half as compared with the case where the colloidal solution shown in FIG. 4 (b) is used. However, it has been found that a constant flow rate is stable although the flow rate is small over a long period of time.

  5 to 8 show another embodiment of the micropump device of the present invention. FIG. 5 shows the pump main body 10, FIG. 6 shows its main part, and FIGS. 7 and 8 show this micropump device. It is a figure which shows the system and its liquid flow which used the.

  The pump main body 10 includes a cylindrical outer cover 12 and a lid 13 and two plate members 14 and 16 on the lower side thereof. Two plate members (hereinafter referred to as an upper plate 14 and a lower plate 16) are part of the microchip 18 in which the micropump device is used, and are formed by grooves formed on the lower surface of the upper plate 14. A discharge liquid channel 20 is formed between the upper plate 14 and the lower plate 16. The microchip 18 is an apparatus for inspecting a solution containing, for example, blood, DNA, cells, and the like, and this micropump apparatus sends such a solution as a discharge liquid Lh to the discharge liquid flow path 20 at a minute flow rate. It ’s liquid.

  At the center in the height direction of the vertical cylindrical casing 12, a porous thin film 22 is arranged so as to bisect the internal space, and a pair of electrodes 24, 26 are arranged above and below the porous thin film 22. Has been. The space above and below the porous thin film 22 (hereinafter, the upper side is called the upstream chamber 28 and the lower side is called the downstream chamber 30) is filled with the working fluid.

  The internal space is vertically divided by the porous thin film 22, but openings of the electrodes 24, 26 facing the porous thin film 22 are formed so as to substantially allow liquid flow. The reason why the porous thin film 22 and the electrodes 24 and 26 are attached to be inclined is to prevent air from remaining inside when supplying the working fluid Lw.

  The hydraulic fluid supply pipes 36 and 38 are respectively provided in the portion below the middle portion of the upstream chamber 28 and the downstream chamber 30, and these are connected to the hydraulic fluid tank 40 via the on-off valves V 1 and V 2. The height of the hydraulic fluid tank 40 and the porous thin film 22, that is, the head h (see FIG. 8) can be set appropriately according to the application, thereby obtaining a desired flow rate characteristic according to the application. In addition, air vent pipes 42 and 44 are respectively provided in the vicinity of the upper stage portion of the upstream chamber 28 and the downstream chamber 30, and these open to the hydraulic fluid recovery container 46 through the on-off valves V 3 and V 4. In addition, the air vent pipe 44 of the downstream chamber 30 is also used as a hydraulic fluid discharge pipe when replenishing the discharge liquid Lh, as will be described later.

  An opening that penetrates the upper plate 14 is formed below the cylindrical casing 12, and a separation membrane 48 that covers the upper end of the opening is provided. The separation membrane 48 is a flexible member made of resin, various rubbers, etc., and is not flat but has a shape in which the center swells. Although it is made of polyethylene in this embodiment, it does not react with the hydraulic fluid Lw or the discharge fluid Lh, and it only needs to have a strength that does not compress or expand with respect to the pressure of about the head h. In this embodiment, the separation membrane 48 is a dome shape having an elliptical cross section, but it may be a circular shape, a cone shape, or an indeterminate shape, and the volume of the protruding portion can be changed by changing the shape. I just need it.

  A space below the separation membrane 48 communicates with the discharge liquid flow path 20, and a discharge chamber 50 is formed in which the discharge liquid Lh is stored and pushed out by the expansion of the porous thin film 22. In addition to the discharge liquid flow path 20, the upper plate 14 is provided with two flow paths leading to the discharge chamber 50, one of which is a supply path 52 for supplying the discharge liquid Lh to the discharge chamber 50, and the other. Is an air vent path 54. As shown in FIG. 6, the replenishment path 52 opens near the bottom of the discharge chamber 50, but the air vent path 54 opens at the base of the porous thin film 22, that is, at the top of the discharge chamber 50. That is, since the air vent path 54 is constituted by a groove formed on the upper surface of the upper plate 14, it is sealed by a joint 56 attached so as to cover it.

  The supply path 52 communicates with a discharge liquid tank 60 with a hand pump 58 via a supply pipe 53 having an on-off valve V5. The air vent path 54 opens to the discharge liquid recovery container 64 through an air vent pipe 63 having an on-off valve V6. For example, the air vent pipe 62 may be formed of a transparent member such as glass at a vertical portion so that the rise in the liquid level can be visually observed. In addition, since the on-off valves V1 to V6 described above affect the operation of the micropump, a precise structure that does not leak when closed is used. In addition, the discharge liquid flow path 20 is provided with an on-off valve V7 for preventing the replenisher from flowing downstream during the start-up operation or replenishment operation.

  The separation membrane 48 may be fixed with an adhesive or the like between the lower end of the outer cover 12 and the edge of the opening of the upper plate 14, or may be sandwiched with screws or clamps so that it can be removed for replacement. You may wear it. The outer cover 12 of the pump body 10 is made of resin or metal, and the upper plate 14 is preferably made of resin such as polydimethylsiloxane (PDMS).

  Hereinafter, operations of the micropump device and the pump system configured as described above will be described. When the system shown in FIG. 7 or FIG. 8 is started with the hydraulic fluid Lw and the discharge liquid Lh of the pump body 10 empty, first, the open / close valves V1 and V2 and the release valve V8 of the discharge liquid tank 60, The on-off valve V7 communicating with the discharge liquid flow path 20 is closed, the on-off valves V4, V5, V6 are opened, the hand pump 58 of the discharge liquid tank 60 is operated, and the discharge liquid Lh is sent to the discharge chamber 50. When the liquid comes out from the front end side of the air vent path 54, the air in the discharge chamber 50 is pushed out, so the on-off valve V7 is closed. The discharge liquid Lh accumulates in the discharge chamber 50 and pushes the separation membrane 48 upward, for example, as shown by a broken line in FIG. In this figure, the separation membrane 48 is exaggerated. When a sufficient amount of the discharge liquid Lh has accumulated in the discharge chamber 50, liquid supply from the discharge liquid tank 60 is stopped and the on-off valve V5 is closed.

  Next, the on-off valves V1 and V2 communicating with the hydraulic fluid tank 40 and the on-off valves V3 and V4 for releasing air are opened, and the hydraulic fluid Lw is supplied to the upstream chamber 28 and the downstream chamber 30. When the hydraulic fluid Lw comes out from the on-off valves V3 and V4, the air venting is finished, so that the on-off valves V1 to V4 can be closed and the micropump operation can be started. In particular, in order to sufficiently release the air in the vicinity of the porous thin film 22 and the electrodes 24 and 26, it is preferable to perform the above-described operation liquid supply operation again after the micro pump is preliminarily operated.

  In the above, the discharge liquid Lh is filled before the working liquid Lw is filled. When the working liquid Lw is supplied with the on-off valve V4 opened, the separation membrane 48 expands downward due to the weight of the working liquid Lw. This is because the discharge liquid Lh cannot be sufficiently supplied. However, if the supply of the hydraulic fluid Lw to the downstream chamber 30 is stopped at a predetermined amount, and then the discharge fluid Lh is supplied with the on-off valve V2 closed and V4 opened, the hydraulic fluid is eventually pushed out from the on-off valve V4. You may do this. Any of the upstream chamber 28, the downstream chamber 30, and the discharge chamber 50 may be filled with the liquid in a state in which air is removed.

  In this way, with each liquid supplied to each chamber, only the on-off valves V1 and V7 are opened and a predetermined voltage is applied between the electrodes 24 and 26 to operate the micropump. The on-off valve V1 is opened in order to keep the head h constant. As a result, the fine particles in the hydraulic fluid Lw pass through the porous thin film 22, and the hydraulic fluid Lw flows from the upstream chamber 28 to the downstream chamber 30 with a small flow rate accordingly. Accordingly, the separation membrane 48 expands downward, the volume of the downstream chamber 30 increases, the volume of the discharge chamber 50 decreases, and the discharge liquid Lh is sent out from the discharge chamber 50 to the discharge liquid flow path. Since the separation membrane 48 is incompressible, the flow rates of the hydraulic fluid Lw and the discharge fluid Lh always match.

  With the operation of the micropump, the volume of the downstream chamber 30 increases, and the separation membrane 48 eventually approaches the original shape shown by the solid line in FIG. Therefore, the operation is stopped at a predetermined timing, and the replenishment work of the discharge liquid Lh is performed. This is achieved by opening the on-off valve V5 of the supply pipe 53 and the on-off valve V4 for releasing the air / discharging hydraulic fluid in the downstream chamber 30 and operating the hand pump 58 with the other on-off valves closed. . As a result, the discharge liquid Lh pumped to the discharge chamber 50 pushes up the separation membrane 48 and pushes the working liquid Lw in the downstream chamber 30 from the air vent / working liquid discharge pipe 44 and the on-off valve V4 to the working liquid collection container 46. When the predetermined amount is supplied, the on-off valves V4 and V5 are closed, the on-off valve V7 is opened, and the operation of the micropump may be resumed.

  FIG. 9 shows another embodiment of the micropump device and the pump system, in which a through-hole is provided in the lower plate 16 of the microchip 18 and a cup-shaped container 66 is attached below the through-hole. The separation membrane 48 increases the height of the dome according to the depth of the discharge chamber 50. The discharge liquid channel 20 is opened at a position where it is not covered by the separation membrane 48. Thus, by increasing the depth of the discharge chamber 50, it is possible to extend the operable period by one discharge liquid replenishment.

  FIG. 10 shows another embodiment of a pump system using a micropump device. In the previous embodiment, the discharge liquid Lh was manually supplied by the hand pump 58. In this embodiment, FIG. Uses a replenishment pump 68 that operates with a predetermined actuator. Further, in this embodiment, there is provided a control device 70 that controls the operation of the replenishment pump 68 and the opening / closing operations of the on-off valves V1 to V7 as necessary, and performs the replenishment operation at a predetermined timing. The timing of performing the replenishment operation may be a method of measuring the operation time of the micropump, measuring the total flow rate with a flow meter or the like, or measuring the deformation of the separation membrane 48 with a sensor. With such a configuration, a micro pump operation that is automated for a long period of time can be performed.

It is a schematic diagram which shows the principle of the micropump apparatus of this invention. (A) is a figure which shows the electrode of the apparatus of FIG. 1, (b) is a figure which shows the conventional electrode. It is a graph which shows the result of 1st Example of this invention compared with the conventional case. (A) is a graph which shows the result of the Example of this invention, (b) is a graph which shows the result in the conventional case. The structure of the main-body part of the micropump apparatus of 1 embodiment of this invention is shown, (a) is a longitudinal cross-sectional view, (b) is a top view. 5A and 5B show a main part of the main body of FIG. 5, where FIG. 5A is a view taken along an arrow a in FIG. 5B, and FIG. 5B is a view taken along an arrow b in FIG. It is a figure which shows the pump system using the micropump apparatus of FIG. It is a figure which shows typically the liquid flow in the pump system using the micropump apparatus of FIG. It is a figure which shows the micro pump apparatus and pump system of other embodiment of this invention. It is a figure which shows the micro pump apparatus and pump system of other embodiment of this invention. It is a figure which shows the principle of a micropump apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Pump main body 12 Enclosure 22 Porous thin film 24,26 Electrode 27 Hole 28 Upstream chamber 30 Downstream chamber 32 Switch 34 DC power supply 36,38 Hydraulic fluid supply pipe 40 Hydraulic fluid tank 42 Air vent pipe 44 Air vent / hydraulic fluid discharge pipe 48 Separation Membrane 50 Discharge chamber 52 Supply path 53 Supply pipe 54 Air vent path 60 Discharge liquid tank 62 Air vent pipe 70 Control device Lh Discharge liquid Lw Hydraulic fluid V1 to V7 On-off valve V8 Open valve

Claims (5)

A porous thin film disposed in the flow path, a pair of electrodes disposed on both sides of the porous thin film, a means for supplying hydraulic fluid to the flow path, and a DC voltage is applied between the pair of electrodes. DC power supply
The pair of electrodes has a plate shape in which a plurality of through holes are formed,
A micropump device that generates a flow of the working fluid through the porous thin film by applying a DC voltage between the pair of electrodes.   The micropump device according to claim 1, wherein the hydraulic fluid is a solution processed so as not to cause electrolysis.   3. The micropump device according to claim 2, wherein the hydraulic fluid is a colloidal solution in which fine particles are dispersed in a liquid.   The micropump device according to claim 2, wherein the hydraulic fluid is ion exchange water or distilled water. A flexible separation membrane is installed on the downstream side of the porous thin film, the discharge liquid is accommodated in a discharge chamber provided on the other side of the separation membrane, and the driving force of the working liquid is discharged through the separation membrane. 5. The micropump device according to claim 1, wherein the micropump device transmits the liquid.

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