Electroosmotic flow pumps and liquid transfer devices

Abstract

To provide a reliable electroosmotic flow pump and liquid delivery device that operates stably. [Solution] An electroosmotic flow pump having a pair of electrodes, a porous body disposed between the pair of electrodes, and a main body covering the pair of electrodes and the porous body. The electroosmotic flow pump has a retention section (gap) of a predetermined width between one electrode and the porous body. The retention section (gap) is for retaining bubbles generated during operation. The electroosmotic flow pump may also have a retention section of a predetermined width in at least a portion between one electrode and the porous body for retaining bubbles generated during operation.

Description

Technical Field

[0001] The present invention relates to an electroosmotic flow pump and various devices equipped with the same.

Background Art

[0002] Conventionally, an electroosmotic flow pump has been used for discharging or sucking a liquid (see, for example, Patent Document 1). The liquid feeding device of Patent Document 1 is configured to perform liquid feeding by driving an electroosmotic flow pump. In Patent Document 1, by using an electroosmotic flow pump, miniaturization of the device, reduction of power consumption, and micro-dose administration of a chemical solution are made possible.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, a conventional electroosmotic flow pump has a structure in which electrodes are brought into contact with both end faces of a porous body and the porous body is sandwiched between a pair of electrodes. When the negative pressure in the flow path increases due to the driving of the pump, bubbles are generated particularly on the inflow side to the porous body. The continuously generated bubbles combine with each other and grow, which hinders the driving of the pump.

[0005] The present invention has been made to solve the above problems, and an object thereof is to provide a highly reliable electroosmotic flow pump and a liquid feeding device that can be stably driven.

Means for Solving the Problems

[0006] An electroosmotic flow pump according to one aspect of the present invention comprises a pair of electrodes, a porous body disposed between the pair of electrodes, and a main body covering the pair of electrodes and the porous body, wherein a gap of a predetermined width is provided between one of the pair of electrodes and the porous body. An electroosmotic flow pump according to one aspect of the present invention comprises a pair of electrodes, a porous body disposed between the pair of electrodes, and a main body covering the pair of electrodes and the porous body, wherein a gap is provided between one of the pair of electrodes and the porous body to retain bubbles generated during operation. An electroosmotic flow pump according to one aspect of the present invention comprises a pair of electrodes, a porous body disposed between the pair of electrodes, and a main body covering the pair of electrodes and the porous body, wherein a retention section having a predetermined width is provided in at least a portion between one of the pair of electrodes and the porous body, for retaining bubbles generated during operation.

[0007] A liquid delivery device according to one aspect of the present invention comprises the above-mentioned electroosmotic flow pump, a first flow channel section having a first flow channel in which the drive fluid is stored and which communicates with the liquid delivery channel of the electroosmotic flow pump, and a second flow channel section having a second flow channel on the opposite side of the first flow channel which communicates with the liquid delivery channel. [Effects of the Invention]

[0008] In this invention, since a gap or retention area is provided between one electrode and the porous body, the bubbles generated during operation can be kept away from the center of the flow path, thereby enabling stable operation of the electroosmotic flow pump. [Brief explanation of the drawing]

[0009] [Figure 1] This is a perspective view showing an example of the configuration of a liquid delivery device according to Embodiment 1 of the present invention. [Figure 2] Figure 1 is a schematic plan view of the liquid delivery device as seen from above. [Figure 3] This is a schematic cross-sectional view along line AA in Figure 2. [Figure 4] This is a schematic cross-sectional view along line BB in Figure 2. [Figure 5]Figure 1 is an explanatory diagram illustrating the generation and retention of bubbles in an electroosmotic flow pump. [Figure 6] This is a schematic plan view showing an example of the configuration of a liquid delivery device according to a modified embodiment of the present invention. [Figure 7] This is a perspective view showing an example of the configuration of a liquid delivery device according to Embodiment 2 of the present invention. [Figure 8] Figure 6 is a schematic cross-sectional view illustrating a cross-section of the liquid delivery device, similar to that shown in Figure 3. [Figure 9] This is an explanatory diagram illustrating the generation and retention of bubbles in an electroosmotic flow pump that mimics a conventional configuration. [Modes for carrying out the invention]

[0010] Embodiment 1. Based on Figures 1 to 5, an example of the electroosmotic flow pump 10 in Embodiment 1 of the present invention and the components used in combination therewith will be described. In each figure, the scale of each component is appropriately changed for the sake of explanation. Also, in each figure, some reference numerals are omitted as appropriate to avoid complexity in the drawings. For the three directions shown in each figure, the x-axis direction is considered to be the left-right direction, the y-axis direction is considered to be the front-back direction, and the z-axis direction is considered to be the up-down direction. In particular, the positive y-axis direction corresponds to the direction of liquid discharge by the electroosmotic flow pump 10, and the negative y-axis direction corresponds to the direction of liquid suction by the electroosmotic flow pump 10.

[0011] First, an example of the configuration of the electroosmotic flow pump 10 and the liquid delivery device 100 will be described with reference to Figures 1 and 2. As shown in Figures 1 and 2, the electroosmotic flow pump 10 has a pair of electrodes (11, 12), a porous body 13 placed between the pair of electrodes, and a main body 15 that covers the pair of electrodes and the porous body 13. That is, the pair of electrodes, the first electrode 11 and the second electrode 12, and the porous body 13 are covered by the main body 15.

[0012] The main body portion 15 is formed of, for example, resin. The main body portion 15 may be formed of a transparent material, a translucent material, or an opaque material. The main body portion 15 may be formed by a plurality of processes. For example, the main body portion 15 may constitute a part thereof in the process of positioning the pair of electrodes and the porous body 13, and may be formed into a complete shape through subsequent molding processes. Different materials may be used in each process, that is, the main body portion 15 may be composed of a plurality of materials.

[0013] The porous body 13 is formed of, for example, porous ceramic. The first electrode 11 and the second electrode 12 have conductivity and include, for example, a conductive substance and rubber. The first electrode 11 and the second electrode 12 are arranged at positions facing each other with the porous body 13 interposed therebetween. A part of the first electrode 11 and the second electrode 12 may be configured and arranged to protrude outside the main body portion 15. The electroosmotic flow pump 10 has a liquid delivery channel 1c communicating between the first electrode 11, the porous body 13, and the second electrode 12.

[0014] The electroosmotic flow pump 10 has a retention portion 18 with a preset width S between the first electrode 11, which is one of the pair of electrodes, and the porous body 13. The retention portion 18 retains the bubbles generated when the electroosmotic flow pump 10 is driven. The width S corresponds to the distance between the first electrode 11 and the porous body 13.

[0015] The retention portion 18 of the first embodiment corresponds to a gap provided over the entire area between the end face of the first electrode 11 and the end face of the porous body 13. The shape of the gap as the retention portion 18 is determined by the shapes of the first electrode 11 and the porous body 13. As shown in FIG. 1, if the first electrode 11 and the porous body 13 are circular in cross section, the retention portion 18 becomes a columnar space surrounded by the first electrode 11, the porous body 13, and the main body portion 15. For example, if the first electrode 11 and the porous body 13 are rectangular in cross section, the retention portion 18 becomes a prismatic space surrounded by the first electrode 11, the porous body 13, and the main body portion 15.

[0016] In FIGS. 1 and 2, a liquid delivery device 100 including an electroosmotic flow pump 10, a first flow path section 20, and a second flow path section 30 is illustrated. The first flow path section 20 has a first flow path 2c communicating with the liquid delivery flow path 1c of the electroosmotic flow pump 10. The first flow path section 20 is, for example, made of resin and is a tubular member having the first flow path 2c. A driving liquid is stored in the first flow path 2c of the first flow path section 20. The driving liquid may be any liquid applicable to an electroosmotic flow pump, such as water or alcohols. The second flow path section 30 has a second flow path 3c communicating with the liquid delivery flow path 1c on the side opposite to the first flow path 2c. The second flow path section 30 is, for example, made of resin and is a tubular member having the second flow path 3c. The second flow path section 30 is filled with a chemical solution or the like.

[0017] In the liquid delivery device 100, the porous body 13 is connected to the first flow path 2c of the first flow path section 20 via the retention section 18 and the first electrode 11, and is connected to the second flow path 3c of the second flow path section 30 via the second electrode 12. That is, the first flow path 2c and the second flow path 3c are connected via the liquid delivery flow path 1c. The first flow path section 20 and the second flow path section 30 may be formed of a transparent material, a translucent material, or an opaque material.

[0018] When a voltage is applied to both ends of the porous body 13 infiltrated with a liquid, a phenomenon occurs in which the liquid in the porous body 13 moves from one end to the other end. This phenomenon is called the electroosmotic flow phenomenon, and the flow of the liquid generated thereby is called the electroosmotic flow. Although not shown, terminals are connected to the pair of electrodes (11, 12), and the electroosmotic flow pump 10 is configured such that a voltage is applied to both ends of the porous body 13 via these terminals. When the retention section 18 is filled with the driving liquid and a voltage is applied to the pair of electrodes (11, 12) in a state where the driving liquid infiltrates the porous body 13, an electroosmotic flow is generated in the porous body 13, and the electroosmotic flow pump 10 functions as a pump for sending out the liquid.

[0019] When a voltage is applied such that the first electrode 11 is the positive electrode and the second electrode 12 is the negative electrode, an electroosmotic flow is generated within the porous body 13 in the direction of the white arrows in Figures 1 and 2, enabling liquid delivery in that direction. On the other hand, when a voltage is applied such that the first electrode 11 is the negative electrode and the second electrode 12 is the positive electrode, an electroosmotic flow is generated within the porous body 13 in the opposite direction to the white arrows in each figure. In other words, the electroosmotic flow pump 10 can reverse the direction of liquid delivery by reversing the polarity of the voltage.

[0020] Figure 1 illustrates the components of a syringe, which are made up in combination with the fluid delivery device 100. These components include a needle section 4 consisting of a needle 4a and a support section 4b, and a connecting section 5 for connecting the needle section 4 to the end of the second flow path section 30. The syringe includes an electroosmotic flow pump 10, a first flow path section 20, a second flow path section 30, and a needle section 4 connected to the end of the second flow path section 30. Additional components may be added to the syringe to facilitate gripping and improve operability.

[0021] Here, referring to Figures 2 and 3, an example of the size of the electroosmotic flow pump 10 and liquid delivery device 100 in this embodiment 1 is shown. For example, the electroosmotic flow pump 10 may have a main body 15 length L of 25 mm, a main body 15 height H of 17 mm, and a stagnation section 18 (gap) width S of 2 mm. The length L and height H of the main body 15 can be changed arbitrarily. The width S can also be adjusted arbitrarily within a range that does not obstruct the flow of liquid in the flow path and does not obstruct conductivity between electrodes.

[0022] In this embodiment 1, a pair of electrodes (11, 12) with an outer diameter D of 8.5 mm are used, and the outer diameter of the porous body 13 is approximately the same, but these can also be changed as needed. In this embodiment 1, a tube with an inner diameter C1 of 1 mm and an outer diameter C2 of 3 mm is used as the first flow channel 20, and a similar tube is used for the second flow channel 30, but the diameters of the first flow channel 20 and the second flow channel 30 are not limited to this example.

[0023] Next, with reference to Figure 4, the flow path of the liquid delivery device 100 will be described. The liquid delivery device 100 has a continuous flow path consisting of a first flow path 2c, a liquid delivery flow path 1c, and a second flow path 3c. In this embodiment 1 of the liquid delivery device 100, the first flow path section 20 is fitted into a hole h1 provided in the first electrode 11, and the second flow path section 30 is fitted into a hole h2 provided in the second electrode 12. Therefore, there is a shared portion between the liquid delivery flow path 1c and the first flow path 2c, and there is also a shared portion between the liquid delivery flow path 1c and the second flow path 3c.

[0024] Figure 4 shows the channel center Ro, which is the center of the liquid delivery channel 1c, as indicated by a dashed line. As can be seen from Figure 4, the retention section 18 functions to retain the bubbles generated when the electroosmotic flow pump 10 is driven, away from the channel center Ro. In other words, the retention section 18 functions to keep the bubbles generated when the electroosmotic flow pump 10 is driven away from the channel center Ro. Specifically, the bubbles F generated upstream of the porous body 13 move upward due to buoyancy, as they are less dense than the liquid. Bubbles attached to the electrodes also move upward once they reach a certain size. In short, the electroosmotic flow pump 10 is configured so that the bubbles generated when it is driven accumulate in the upper part of the retention section 18.

[0025] Figure 4 shows an example in which the first flow channel section 20 is fitted into the entire area of ​​hole h1 and the second flow channel section 30 is fitted into the entire area of ​​hole h2 for convenience. However, the degree to which the first flow channel section 20 and the second flow channel section 30 are fitted can be adjusted as appropriate.

[0026] Next, with reference to Figures 5 and 9, the advantages of the electroosmotic flow pump 10 in this embodiment 1 will be explained. Figure 5 is an explanatory diagram illustrating the generation and retention of bubbles in the electroosmotic flow pump 10. Figure 9 is an explanatory diagram illustrating the generation and retention of bubbles in an electroosmotic flow pump 510 that mimics a conventional configuration.

[0027] Figure 9 shows a schematic cross-section of the electroosmotic flow pump 510, similar to that in Figure 5. However, since the end face of the porous body and the end face of the electrode 511 are in contact, Figure 9 shows a cross-section of the electrode 511. For the sake of explanation, Figure 9 shows a main body 515 with the same shape as the main body 15 and a flow channel 520 with the same shape as the first flow channel 20, but these are not necessarily conventional configurations. In conventional electroosmotic flow pumps, where both end faces of the porous body are in contact with each of the pair of electrodes, as shown in Figure 9, bubbles F generated upstream of the porous body accumulate in the flow channel, combine with each other, and the proportion of bubbles blocking the flow channel increases over time. This hinders the operation of the electroosmotic flow pump.

[0028] On the other hand, since the electroosmotic flow pump 10 has a retention section 18 (gap) between the first electrode 11 and the porous body 13, the foam F generated upstream of the porous body 13 adheres to the first electrode 11 and moves to the upper part of the retention section 18 by buoyancy, as illustrated in Figure 5. Because the electroosmotic flow pump 10 has a region above the flow path connected to the first flow path 2c where the foam F can escape due to the retention section 18, foam F will not accumulate in the liquid delivery flow path 1c unless it is operated for a very long time. In other words, this configuration makes it possible to provide a stable and long-life electroosmotic flow pump 10.

[0029] As described above, the electroosmotic flow pump 10 of this embodiment 1 has a pair of electrodes (11, 12), a porous body 13 disposed between the pair of electrodes, and a main body 15 that covers the pair of electrodes and the porous body 13. A retention section 18, which is a gap of a predetermined width, is provided between the first electrode 11, which is one of the pair of electrodes, and the porous body 13. Therefore, bubbles generated during operation can be kept away from the flow path center Ro and retained at a position away from the flow path center Ro, thus providing a highly reliable electroosmotic flow pump 10 that operates stably. Furthermore, by using the electroosmotic flow pump 10, liquid can be discharged or sucked smoothly.

[0030] <Variation> Referring to Figure 6, an electroosmotic flow pump 10A according to a modified embodiment 1 of the present invention will be described. The electroosmotic flow pump 10A in this modified embodiment is characterized by having retention sections 18 between the first electrode 11 and the porous body 13, and between the second electrode 12 and the porous body 13. The other configurations are the same as those in the examples in Figures 1 to 5. Therefore, the same reference numerals are used for the same components as in Figures 1 to 5, and their descriptions are omitted or simplified.

[0031] The electroosmotic flow pump 10A has a retention section 18 with a width Sa between the first electrode 11, which is one of a pair of electrodes, and the porous body 13, and a retention section 18 with a width Sb between the second electrode 12, which is the other of the pair of electrodes, and the porous body 13. Each retention section 18 is for retaining bubbles generated during operation. The width Sa of the retention section 18 on the first electrode 11 side and the width Sb of the retention section 18 on the second electrode 12 side may be equal or different.

[0032] As described above, since the electroosmotic flow pump 10A has retention sections 18 (gaps) on both sides of the porous body 13, it can move the generated bubbles away from the flow path center Ro and cause them to accumulate in a location away from the flow path center Ro, not only when flowing liquid in the direction from the first electrode 11 to the second electrode 12, but also when flowing in the opposite direction. Therefore, the electroosmotic flow pump 10 can achieve stable operation and a long lifespan even when the direction of liquid delivery is switched during use. Furthermore, since the electroosmotic flow pump 10A has retention sections 18 (gaps) on both sides of the porous body 13, it can be used without being conscious of the direction of use. For example, the electroosmotic flow pump 10A can be suitably used even when the first flow path section 20 is connected to the second electrode 12 and the second flow path section 30 is connected to the first electrode 11 to constitute a liquid delivery device 100.

[0033] Embodiment 2. Based on Figures 7 and 8, an example of the electroosmotic flow pump 110 in Embodiment 2 of the present invention and the components used in combination therewith will be described. For the electroosmotic flow pump 110, components similar to those of the electroosmotic flow pumps 10 and 10A in Embodiment 1 will be given the same reference numerals, and their descriptions will be omitted or simplified. Other details for each figure are the same as in Figures 1 to 6.

[0034] The electroosmotic flow pump 110 of this second embodiment includes a pair of electrodes (111, 12), a porous body 13 positioned between the pair of electrodes, and a main body 15 covering the pair of electrodes and the porous body 13. The electroosmotic flow pump 110 is provided with a retention section 19 having a preset width S in a portion between one of the pair of electrodes (first electrode 111) and the porous body 13, for retaining bubbles generated during operation. In the electroosmotic flow pump 110 illustrated in Figures 7 and 8, the shape of the first electrode 111 differs from that of the first electrode 11 of the first embodiment, and as a result, the shape and volume of the retention section 19 differ from those of the retention section 18 of the first embodiment.

[0035] As illustrated in Figure 7, the first electrode 111 has a columnar base 11m and a contact portion 11n formed to rise from a part of the end face of the base 11m. However, the base 11m and the contact portion 11n are separate for illustrative purposes, and the first electrode 111 may be integrally molded. The end face of the contact portion 11n is positioned to contact the end face of the porous body 13.

[0036] Figure 8 is a schematic cross-sectional view illustrating a cross-section similar to that in Figure 3 of the electroosmotic flow pump 110. Unlike Figure 3, Figure 8 shows the cross-section of the contact portion 11n. The contact portion 11n may, for example, have an annular cross-section with a portion cut out, and the angle of the cut-out portion can be arbitrarily set considering the amount of foam to be retained and the contact stability with the porous body 13. Figures 7 and 8 illustrate a contact portion 11n with a semi-annular cross-sectional shape (angle of the cut-out portion is 180 degrees). The outer shape of the contact portion 11n is changed according to the shape of the base portion 11m.

[0037] As described above, the electroosmotic flow pump 110 includes a pair of electrodes (111, 12), a porous body 13 positioned between the pair of electrodes, and a main body 15 covering the pair of electrodes and the porous body 13. The electroosmotic flow pump 110 is provided with a retention section 19 having a preset width S in at least a portion between the first electrode 111 (one of the pair of electrodes) and the porous body 13, which is used to retain bubbles generated during operation. Therefore, bubbles generated during operation can be kept away from the flow path center Ro and retained at a position away from the flow path center Ro, thus providing a stable, reliable, and long-life electroosmotic flow pump 110. Furthermore, by using the electroosmotic flow pump 110, liquid discharge or suction can be performed smoothly.

[0038] The embodiments described above are merely examples of electroosmotic flow pumps and liquid delivery devices, and the technical scope of the present invention is not limited to these embodiments. For example, the lengths of the first flow channel 20 and the second flow channel 30 can be arbitrarily changed. In the above description, examples were shown in which the first flow channel 20 and the second flow channel 30 are tubular members, but the invention is not limited to this. At least one of the first flow channel 20 and the second flow channel 30 may be a resin member having a flow channel of various curved shapes, such as an S-shape, a continuous S-shape, or a meandering shape, and may include a storage tank in which liquid is stored. In each figure, a rectangular parallelepiped body 15 is illustrated, but the shape of the body 15 is not limited to this. For example, the body 15 may be cylindrical and may have a curved portion.

[0039] The modified configuration is also applicable to the electroosmotic flow pump 110 of this second embodiment. That is, the electroosmotic flow pump 110 may have retention sections 19 on both sides of the porous body 13, similar to the electroosmotic flow pump 10A illustrated in Figure 6. More specifically, the electroosmotic flow pump 110 may be configured to have a second electrode having the same shape as the first electrode 111, that is, a second electrode consisting of a columnar base and a contact section formed to stand upright from a part of the end face of the base, instead of the second electrode 12. Furthermore, the electroosmotic flow pump 10A according to the modified configuration illustrated in Figure 6 may be configured to have a retention section 19 instead of the retention section 18 on the first electrode 11 side or the retention section 18 on the second electrode 12 side. In other words, the electroosmotic flow pump 10A may have a first electrode 111 instead of the first electrode 11, and may have a second electrode consisting of a base and a contact section instead of the second electrode 12. [Explanation of Symbols]

[0040] 1c Fluid delivery channel, 2c First channel, 3c Second channel, 4 Needle section, 4a Injection needle, 4b Support section, 5 Connecting section, 10, 10A, 110 Electroosmotic flow pump, 11, 111 First electrode, 11m Base, 11n Contact section, 12 Second electrode, 13 Porous body, 15 Main body, 18, 19 Retention section, 20 First channel section, 30 Second channel section, 100 Fluid delivery device, C1 Inner diameter, C2 Outer diameter, D Outer diameter, H Height, Ro Center of channel, h1, h2 Hole.

Claims

1. A device comprising a pair of columnar electrodes, a columnar porous body disposed between the pair of electrodes, and a main body covering the pair of electrodes and the porous body, The pair of electrodes and the porous body are used in a orientation where they are side by side. An electroosmotic flow pump wherein a gap of a predetermined width is provided between one end face of the pair of electrodes and the end face of the porous body.

2. A device comprising a pair of columnar electrodes, a columnar porous body disposed between the pair of electrodes, and a main body covering the pair of electrodes and the porous body, The pair of electrodes and the porous body are used in a orientation where they are side by side. One of the pair of electrodes is A columnar base, It has a contact portion that is erected from a part of the end face of the base and contacts the end face of the porous body, An electroosmotic flow pump wherein a gap having a predetermined width is provided between the end face of the base, excluding the portion where the contact portion is erected, and the end face of the porous body.

3. The electroosmotic flow pump according to claim 1 or 2, wherein a gap of a predetermined width is provided between the other end face of the pair of electrodes and the end face of the porous body.

4. A device comprising a pair of columnar electrodes, a columnar porous body disposed between the pair of electrodes, and a main body covering the pair of electrodes and the porous body, The pair of electrodes and the porous body are used in a orientation where they are side by side. The pair of electrodes, respectively, A columnar base, It has a contact portion that is erected from a part of the end face of the base and contacts the end face of the porous body, An electroosmotic flow pump wherein a gap having a predetermined width is provided between the end faces of the bases of each of the pair of electrodes, excluding the portion where the contact portion is erected, and each end face of the porous body.

5. An electroosmotic flow pump according to any one of claims 1, 2, or 4, A first channel section has a first channel that stores the driving fluid and communicates with the fluid delivery channel of the electroosmotic flow pump, A liquid delivery device comprising: a second flow channel section having a second flow channel that communicates with the liquid delivery channel on the opposite side of the first flow channel.

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