JP5306134B2 - Liquid feeding device - Google Patents

Description

  The present invention is a liquid feeding device for feeding a liquid in a flow path formed on an insulating substrate by an electroosmotic flow, and an electroosmotic flow phenomenon generated between the liquid and a dielectric in contact with the liquid. The present invention relates to a liquid feeding device used as a liquid feeding mechanism.

  In the field of chemical technology and biotechnology, research is being conducted to perform reaction to reagents and analysis of samples in a minute area, and chemical reaction using MEMS (Micro Electro Mechanical System) technology. Research and development of microchemical systems that have miniaturized systems such as biochemical reaction and sample analysis are underway.

  Reactions and analyzes in a microchemical system are performed using a single chip called a microchemical chip on which a microchannel, a micropump, a microreactor, and the like are formed. For example, a supply port for supplying a fluid such as a sample or a reagent (a mixture of a solute in a liquid such as water) to a single substrate made of silicon, glass, or resin, and for deriving the processed fluid A microchemical chip in which a feeding port and a sampling port are connected by a microchannel having a small cross-sectional area, and a liquid feeding device is disposed at an appropriate position in the microchannel Has been proposed (see, for example, Patent Documents 1 and 2).

  Conventionally, as a liquid feeding device, a device using a mechanical reciprocating motion of a liquid feeding device such as a piezoelectric type as proposed in Patent Documents 1 and 2 has been mainly employed. Electroosmotic pumps are attracting attention because it is necessary to deliver a very small amount of fluid containing multiple substances at a constant flow rate with higher accuracy in order to perform reactions and analysis with high accuracy. .

  Since the electroosmotic pump does not require a check valve that is required for a liquid feeding device using a mechanical reciprocating motion such as a piezoelectric type, the structure of the pump is simple and the size can be reduced. Since the pulsation of the liquid generated when the check valve operates does not occur, the liquid can be fed at a stable flow rate. Furthermore, the electroosmotic flow pump has an external electric field applied to the electric double layer generated at the interface between the liquid micro-channel wall of the electroosmotic material that plays the role of the liquid feeding mechanism and the electric charge of the electric double layer moves. Since it is possible to send liquid, there is no flow velocity distribution caused by friction between the liquid and the micro flow path wall of the porous body of electroosmotic material. It becomes possible to liquid.

  However, in an electroosmotic pump, since a voltage is applied to the electrode while immersed in a liquid, oxygen and hydrogen generated in the positive electrode and the negative electrode due to electrolysis of water in the liquid are bubbles. Thus, there is a problem that the bubbles inhibit stable liquid feeding.

  To solve this problem, for example, the liquid in which bubbles are mixed is collected at a predetermined location of the flow path by the guide member, and the gas and the liquid are separated by passing through the liquid permeable film and the gas permeable film. A method has been proposed in which only the liquid is fed to the downstream flow path (see, for example, Patent Document 3).

Japanese Patent Laid-Open No. 2002-214241 Japanese Patent Laid-Open No. 2002-233792 JP 2008-223627 A

  However, in the electroosmotic flow pump as disclosed in Patent Document 3, it is necessary to install a bubble guide member in the flow path following the pump section, and the flow path following the pump section by the size of the guide member. However, there is a problem that it is difficult to cope with downsizing. In addition, the introduction of the guiding member in the flow path physically impedes liquid feeding, and the liquid feeding efficiency deteriorates, so that it takes time to complete the liquid feeding at a constant flow rate. There is a problem that the analysis cost increases due to an increase in electric power required for liquid feeding.

  The present invention has been devised to solve such problems in the prior art, and the object thereof is to efficiently remove bubbles mixed in the liquid to be fed, and stable liquid feeding. An object of the present invention is to provide a liquid feeding device capable of performing the above.

In the liquid delivery device of the present invention, the first electrode on the upstream side of the electroosmotic material composed of a porous body mainly composed of silica and the second on the downstream side of the flow path through which the aqueous solution formed on the insulating substrate flows. An electroosmotic pump provided so that the electrodes face each other is provided, and the first electrode and the second electrode are not opposed to each other and are filled with the aqueous solution adjacent to the electroosmotic pump. and has space is provided, wherein there from electroosmotic member at a position far opposed to the electroosmotic member, the inner wall surface parallel to the flow direction of the flow path before Symbol space, before Symbol space A heater for heating the aqueous solution is provided , and the heater is provided so as to be located on a side closer to the second electrode of the inner wall surface .

  Moreover, the liquid feeding device of the present invention is characterized in that, in the above configuration, the electroosmotic material is housed in a facing space where the first electrode and the second electrode face each other.

  The liquid delivery device of the present invention is characterized in that, in the above configuration, the heater is provided on a side closer to at least one of the first electrode and the second electrode in the inner wall surface. is there.

  Moreover, the liquid feeding device of the present invention is characterized in that, in the above configuration, the space has an opening for exposing the aqueous solution.

  According to the liquid feeding device of the present invention, the space where the first electrode and the second electrode are not opposed to each other and the aqueous solution is filled is provided adjacent to the electroosmotic flow pump. A heater for heating the aqueous solution in the space is provided on the inner wall surface along the flow direction or in the insulating substrate adjacent to the inner wall surface. By heating the aqueous solution in the space with this heater, the liquid temperature of the aqueous solution in the space rises, and between the liquid temperature in this space and the liquid temperature in the vicinity of the first electrode and the second electrode of the electroosmotic flow pump. Produces a temperature gradient. Since the surface tension of the liquid decreases as the temperature rises, this temperature gradient causes a surface tension gradient at the gas-liquid interface, so that it is adjacent to the first electrode and the second electrode of the electroosmotic flow pump along the gas-liquid interface. Convection occurs in the space where the gas flows, and bubbles generated in the first electrode and the second electrode of the electroosmotic flow pump are collected in the adjacent spaces by this convection, so that the bubbles are separated from the aqueous solution. Therefore, it is possible to prevent the bubbles from being sent to the flow path in the downstream region of the electroosmotic flow pump. Since the bubbles generated at the first electrode and the second electrode of the electroosmotic pump are extremely small, it is difficult to efficiently collect them with the induction device as in the prior art. According to this, bubbles in the aqueous solution can be easily collected.

  In addition, according to the liquid feeding device of the present invention, since no bubble guide member is required in the flow path as in the prior art, it is possible to cope with downsizing and the liquid feeding is physically hindered by the guidance device. Since the liquid feeding efficiency can be maintained, it is possible to provide a liquid feeding device corresponding to a lower cost.

  Further, according to the liquid delivery device of the present invention, when the electroosmotic material is accommodated in the facing space where the first electrode and the second electrode face each other, in the facing space between the first electrode and the second electrode. Since the electric field density is constant, the electric field density can be made constant without changing the flow rate of the aqueous solution. Therefore, the frequency of occurrence of bubbles generated on the surfaces of the first electrode and the second electrode of the electroosmotic pump Becomes constant, and bubbles can be efficiently collected in the adjacent space.

  Further, according to the liquid delivery device of the present invention, when the heater is provided on the side closer to at least one of the first electrode and the second electrode on the inner wall surface along the flow direction of the flow path of the space, When the amount of bubbles generated in the first electrode and the second electrode is different, it is possible to efficiently collect bubbles by providing a heater on the side closer to the electrode that generates more bubbles.

  Further, according to the liquid delivery device of the present invention, when the space has an opening for exposing the aqueous solution, it is possible to remove the bubbles collected in the space through the opening by releasing them from the liquid into the atmosphere, It is possible to remove bubbles continuously and stably.

It is a top view which shows an example of embodiment of the liquid feeding apparatus of this invention. (A) is a top view showing an example of embodiment of the liquid feeding apparatus of this invention, (b) is a fragmentary sectional view which shows the cross-sectional structure in the II cross section of (a). It is a disassembled perspective view which shows typically an example of the manufacturing method of the liquid feeding apparatus of this invention.

  Hereinafter, examples of embodiments of the liquid delivery device of the present invention will be described with reference to the drawings.

  However, in the drawings referred to below, for the convenience of explanation, among the constituent members in an example of the embodiment of the present invention, only the main members necessary for explaining the present invention are shown in a simplified manner. Therefore, the liquid delivery device of the present invention can include arbitrary constituent members not shown in the drawings. Moreover, the dimension of the structural member in each figure does not faithfully represent the actual dimension of the structural member, the dimensional ratio of each structural member, or the like.

  FIG. 1 is a plan view showing an example of a liquid feeding device 11 which is an example of an embodiment of a liquid feeding device of the present invention. 2 is an enlarged view of the electroosmotic flow pump 16 shown in FIG. 1, (a) is a plan view of the electroosmotic flow pump 16, and (b) is an I in FIG. 2 (a). It is -I sectional drawing. As shown in FIG. 1, the liquid feeding device 11 of this example includes an insulating substrate 12, a supply unit 13, a flow path 14, a sampling unit 15, and an electroosmotic flow pump 16 (first electrode 26, second electrode 27 and A heater 28 and the like).

  Here, the liquid feeding device 11 of the present example can be used, for example, for testing biological materials such as viruses or bacteria in body fluids such as blood, saliva, or urine. Further, the liquid delivery device 11 of this example can be used for, for example, a reaction experiment between bacteria and a chemical solution, blood identification, separation extraction or decomposition with a chemical solution of a gene, mixing of a plurality of chemical solutions, etc. It can also be used for other purposes.

  The insulating substrate 12 is configured by laminating a plurality of insulating layers. Here, the insulating substrate 12 is made of an insulating material such as ceramics, silicon, or glass, but is preferably made of ceramics. This is because when the insulating substrate 12 is made of ceramics, the compatibility with the biomaterial contained in the aqueous solution and fed to the flow path 14 is improved, and the chemical resistance and the like are also excellent. The ceramic used for the insulating substrate 12 is, for example, an aluminum oxide sintered body, an aluminum nitride sintered body, a mullite sintered body, a silicon carbide sintered body, a silicon nitride sintered body, or a glass ceramic sintered body. Etc.

  The insulating substrate 12 does not necessarily need to be composed of a plurality of insulating layers, and may be composed of one insulating layer. However, in order to provide the electroosmotic pump 16 described later on the insulating substrate 12, the insulating substrate 12 is preferably composed of a plurality of insulating layers from the viewpoint of ease of manufacture.

  The aqueous solution supply unit 13 to the flow path 14 is formed on the insulating substrate 12, and is a member that plays a role in supplying the aqueous solution to the flow path 14. In the present example, the supply unit 13 includes a first supply unit 13a and a second supply unit 13b. The first supply part 13a and the second supply part 13b are provided by forming a through hole from the surface to the flow path 14 in the insulating substrate 12 so that the aqueous solution can be supplied to the flow path 14 from the outside.

  The flow path 14 is a member that is formed in the insulating substrate 12 and plays a role for the aqueous solution supplied from the supply unit 13 to flow. In this example, the flow path 14 is formed not only on the surface layer of the insulating substrate 12 but also on the inner layer.

  The junction C is a location where the aqueous solution supplied from the first supply unit 13a and the aqueous solution supplied from the second supply unit 13b merge. Moreover, the process part P is a location which heat-processes the aqueous solution joined by the junction part C with the heater etc. which are not shown in figure, for example. In other words, by subjecting the aqueous solution joined by the joining part C to heat treatment, the chemical reaction between the aqueous solution supplied from the first supply part 13a and the aqueous solution supplied from the second supply part 13b can be promoted.

  The collection unit 15 is formed on the insulating substrate 12 and is a member that plays a role for collecting a reactive substance in an aqueous solution processed by the processing unit P, for example. In this example, the collection unit 15 is realized by forming a through-hole extending from the flow path 14 to the surface of the insulating substrate 12 so that the reactive substance in the aqueous solution can be extracted to the outside.

  The electroosmotic pump 16 is formed in the flow path 14 for sending an aqueous solution to the insulating substrate 12 from the supply unit 13 to the processing unit P, and the first electrode 26 formed in the electroosmotic pump 16 A voltage can be supplied to the electroosmotic pump 16 by applying a predetermined voltage to the second electrode 27 using a power supply device (not shown).

  The first electrode 26 and the second electrode 27 in the electroosmotic flow pump 16 are opposed to the wall surface orthogonal to the flow direction of the flow path 14 among the inner wall surfaces of the hole 22 in which the electroosmotic flow pump 16 is formed. It is formed as follows.

  The space 25 is formed adjacent to the electroosmotic pump 16 without the first electrode 26 and the second electrode 27 facing each other, and is filled with an aqueous solution.

  The heater 28 is formed in the inner wall surface 29 along the direction of the flow of the flow path 14 in the space 25 or in the insulating substrate 12 adjacent to the inner wall surface 29 along the flow direction, and heats the aqueous solution in the space 25. .

  The space 25 preferably has an opening 30 exposed to the atmosphere in order to open bubbles (not shown) collected by the heater 28 to the atmosphere in the aqueous solution filled in the space 25. For example, when a lid (not shown) is installed at the site of the electroosmotic flow pump 16, a lid that covers all of the space 25 is installed, and an opening 30 is provided at the site located on the space 25. .

  Here, by heating the heater 28, the liquid temperature of the aqueous solution in the space 25 rises, and the liquid temperature in the space 25 and the liquid temperatures in the vicinity of the first and second electrodes 26 and 27 of the electroosmotic pump 16 A temperature gradient occurs between the two. Since the surface tension of the liquid decreases as the temperature rises, a surface tension gradient is generated at the gas-liquid interface due to this temperature gradient, so that the first and second electrodes 26 and 27 of the electroosmotic flow pump 16 move along the gas-liquid interface. Convection of the aqueous solution occurs toward the space 25, and bubbles generated in the first and second electrodes 26 and 27 of the electroosmotic flow pump 16 are collected in the space 25 by this convection. It is possible to prevent bubbles from being sent to the flow path 14 in the downstream area. Since the bubbles generated at the first and second electrodes 26 and 27 of the electroosmotic flow pump 16 are extremely small, it is difficult to efficiently collect them by using an induction member as in the prior art. According to this liquid feeding device, it is possible to easily collect extremely fine bubbles in the aqueous solution. In addition, since a bubble guiding member as in the prior art is not required, it is possible to cope with downsizing, and liquid feeding is not hindered by the guiding member, so that good liquid feeding efficiency can be maintained. Therefore, it is possible to manufacture a liquid feeding device corresponding to a lower cost.

  The heating temperature of the heater 28 needs to be set in a temperature range in which convection due to the surface tension gradient occurs in the aqueous solution from the electroosmotic flow pump 16 to the space 25, and bubbles can be collected efficiently. For example, when blood is fed as an aqueous solution, it is preferably set in the range of 50 to 80 ° C. If the temperature is lower than 50 ° C., it is difficult to generate a temperature gradient, and thus it is difficult to efficiently introduce bubbles into the space 25. On the other hand, if the temperature is higher than 80 ° C., convection is inhibited by bubbles generated by boiling of water in the blood.

  The volume of the space 25 is preferably set to 10 to 30% with respect to the total volume of the electroosmotic pump 16 and the hole 22 in which the space 25 is formed. The volume of the space 25 may be varied by changing the volume of the electroosmotic material 21 occupying the hole 22. If the volume of the space 25 is smaller than 10%, it is not preferable because the space for collecting bubbles is narrow and it is difficult to efficiently collect bubbles. On the other hand, if the volume of the space 25 is larger than 30%, the volume of the electroosmotic material 21 becomes small, and the liquid feeding effect by electroosmosis becomes small, which is not preferable.

  In addition, the electroosmotic material 21 is preferably contained in a facing space where the first electrode 26 and the second electrode 27 face each other. Thereby, since the electric field density is constant in the space between the first electrode 26 and the second electrode 27, the flow rate of the aqueous solution does not change due to the electric field density, so the first and second electrodes 26 , 27, the frequency of bubbles generated on the surface becomes constant, and the bubbles can be collected efficiently.

  The material of the electroosmotic material 21 is preferably a silica porous body having a high zeta potential and high liquid feeding efficiency in the electroosmosis phenomenon, an average pore diameter of 20 to 50 μm, and a pore opening ratio of more than 50%. Is preferred. If the pore diameter is smaller than 20 μm or the pore opening ratio is smaller than 50%, the pressure loss in the pores is increased, the liquid feeding amount is decreased, and the liquid feeding efficiency tends to be deteriorated. On the other hand, when the pore diameter is larger than 50 μm, the effect of the electroosmosis phenomenon is reduced, and the liquid feeding efficiency tends to deteriorate.

  As the material of the electroosmotic material 21, alumina, zirconia, titania or the like can be used in addition to silica. This is because these materials have a relatively high zeta potential as compared with other metal materials or organic materials, and can easily form an electric double layer at the interface with an aqueous solution.

  The arrangement of the electroosmotic material 21 is such that the electroosmotic material 21 and the first and second electrodes are secured in order to secure a path for guiding bubbles generated on the surfaces of the first and second electrodes 26 and 27 to the heater 28. It is preferable to provide a gap of about 500 to 2000 μm between 26 and 27. If the gap between the electroosmotic material 21 and the first and second electrodes 26 and 27 is smaller than 500 μm, it is not possible to secure a sufficient bubble path and it is difficult to efficiently collect pores. Absent. On the other hand, when the gap between the electroosmotic material 21 and the first and second electrodes 26 and 27 is larger than 2000 μm, the distance between the first and second electrodes 26 and 27 increases, so that the electric field density is reduced. Since it becomes small, the effect of the electroosmosis phenomenon becomes small and the liquid feeding efficiency tends to deteriorate, which is not preferable.

  The heater 28 may be provided on the inner wall surface 21 on the side close to at least one of the first electrode 26 and the second electrode 27, preferably on the side close to the downstream electrode. In this case, since the amount of bubbles generated between the first electrode 26 and the second electrode 27 is different, by providing the electrode on the side where the amount of bubbles is large, usually on the side closer to the downstream electrode, It is preferable because air bubbles generated at the downstream electrode can be collected more effectively, and generation of air bubbles flowing in the flow path 14 in the downstream region than the electroosmotic flow pump 16 can be suppressed.

  Next, an example of an embodiment of a method for manufacturing a liquid feeding device according to the present invention will be described with reference to FIG.

  First, an appropriate organic binder and solvent are mixed with the raw material powder, and if necessary, a plasticizer or a dispersant is added to form a slurry, which is formed into a sheet by the doctor blade method or the calender roll method. A ceramic green sheet is formed. As the raw material powder, for example, if the insulating substrate 12 is made of an aluminum oxide sintered body, aluminum oxide, silicon oxide, magnesium oxide, calcium oxide, or the like is used.

  In this example, the insulating substrate 12 is formed by laminating a number of ceramic green sheets formed in this way. As the number of ceramic green sheets stacked and the number of ceramic green sheets forming through holes, the numbers described below are merely examples, and can be appropriately changed according to the amount of aqueous solution to be fed and the like.

  First, as shown to Fig.3 (a), the through-hole 33a used as an upstream flow path and the through-hole 34a used as a downstream flow path are formed in the ceramic green sheets 31a-31e. In addition, the electroosmotic material 21 is inserted to form a through hole 32 that becomes a hole 22 necessary to form the space 25.

  Further, a groove 33b serving as an upstream channel and a groove serving as a downstream channel for forming channels 23b and 24b having a smaller channel diameter than the upstream channel 33a and the downstream channel 34a in the ceramic green sheets 31b and 31d. 34b is formed. In the example shown in FIG. 3 (a), the number of grooves 33b serving as the upstream flow path and the number of grooves 34b serving as the downstream flow path are formed at two locations in each of the upstream area and the downstream area. Depending on the flow rate, the number of the grooves 33b serving as the upstream channel and the number of the grooves 34b serving as the downstream channel are set. These through-holes are formed by punching with a mold or drilling such as laser processing, and the grooves are formed by pressing the mold and denting the surfaces of the ceramic green sheets 31b and 31d, or by laser processing. The When there are two channels 23b and 24b each having a smaller channel diameter than the upstream channel 33a and the downstream channel 34a in each of the upstream region and the downstream region, it may be a through hole. You may form simultaneously with the hole 33a and the through-hole 34a used as a downstream flow path.

  Next, the ceramic green sheets 31a to 31g are laminated to form a laminated body 40 of ceramic green sheets as shown in FIG. Of the inner wall surface of the through hole 32 that becomes the hole 22 formed in the laminated body 40 of the laminated ceramic green sheets, the first electrode 26 is formed by end-printing the conductive paste on the inner wall surface 35 perpendicular to the flow path. An end face electrode 36 and an end face electrode 37 to be the second electrode 27 are formed.

  The end face electrode 36 to be the first electrode 26 and the end face electrode 37 to be the second electrode 27 are made of a conductive paste prepared by mixing metal powder, an organic binder and a solvent on the inner wall surface of the through hole 32. It is formed by painting with a pattern. As the material of the metal powder, tungsten, molybdenum, platinum or the like is used, and platinum that is excellent in chemical resistance and does not restrict the type of aqueous solution distributed to the microchemical chip is particularly preferable.

  Next, among the inner wall surfaces of the through-holes 32 formed in the laminated body 40 of the laminated ceramic green sheets, the end surface that becomes the heater 28 on the inner wall surface 39 along the flow direction, preferably parallel to the flow direction An electrode 38 is formed. The end face electrode 38 that becomes the heater 28 is formed on a surface far from the electroosmotic material 21 to be described later, and is disposed on the downstream side of the end face electrode 36 that becomes the first electrode 26 and the end face electrode 37 that becomes the second electrode 27. It is formed on the side close to. The printing area of the end face electrode 38 to be the heater 28 is preferably formed in a range of 50 to 70% with respect to the entire area of the inner wall surface 39 parallel to the flow direction. If this area is smaller than 50%, the heating area for the space 25 becomes narrower, and the temperature gradient between the aqueous solution in the space 25 and the aqueous solution in the vicinity of the first electrode 26 and 27 near the upstream electrode. This is not preferable because it is difficult to sufficiently generate bubbles, and it is difficult to collect bubbles generated on the surface of the electrode near the upstream side. On the other hand, if this area is larger than 70%, the entire aqueous solution in the hole 22 is heated, and the temperature gradient between the aqueous solution in the space 25 and the aqueous solution in the vicinity of the first and second electrodes 26 and 27 is sufficiently high. This is not preferable because it is difficult to efficiently generate bubbles generated at the downstream electrode where a large amount of bubbles are generated.

  The end face electrode 38 to be the heater 28 is formed by applying a conductive paste prepared by mixing metal powder, an organic binder and a solvent to the inner wall surface of the through hole 32 to be the hole 22 in a predetermined pattern. To do. As the material of the metal powder, various resistor materials can be used, but ruthenium oxide having a high specific resistance and easily generating heat even with a small current is particularly desirable.

  When the heater 28 is provided in the insulating substrate 12 close to the inner wall surface 39 along the flow direction of the flow path 14 in the space 25, a predetermined location in the vicinity of the through hole 32 of the ceramic green sheets 31b to 31f is previously provided. The surface electrode pattern to be the heater 28 is formed with a conductive paste using screen printing or gravure printing, and the ceramic green sheets 31a to 31g are laminated, so that the flow direction of the flow path 14 in the space 25 is aligned. The desired heater 28 can be formed in the insulating base 12 close to the inner wall surface 39. The pattern of the surface electrode serving as the heater 28 is formed at a location in the vicinity of the space 25 after lamination, in the vicinity of the through hole 32 formed in the ceramic green sheets 31b to 31f. At this time, the length of the region where the pattern of the surface electrode is formed is in the range of 50 to 70% with respect to the length of the side of the portion that becomes the inner wall surface 39 in the flow direction of the space 25. It is preferable.

  Next, the ceramic green sheet laminate 40 produced as described above is sintered at a temperature corresponding to the ceramic material, for example, at about 1600 ° C. for an aluminum oxide sintered body. The atmosphere during sintering is preferably a reducing atmosphere in order to prevent oxidation of the conductive paste.

  Next, the electroosmotic material 21 is embedded in the hole 22 inside the electroosmotic flow pump 16 of the sintered insulating substrate 12. The dimension of the electroosmotic material 21 is 500 to 500 between the electroosmotic material 21 and the end surface electrode 36 serving as the first electrode 26 and the end surface electrode 37 serving as the second electrode 27 in the flow direction of the aqueous solution. Design and install so that a gap of 2000 μm is created. Further, the volume of the space 25 is determined by the volume occupied by the hole 22 of the electroosmotic material 21, but the dimension of the electroosmotic material 21 is such that the volume of the space 25 is 10 to 30% with respect to the total volume of the hole 22. Design and install.

  Next, when a lid is used for the liquid feeding device 11, a lid (not shown) in which a through-hole as the opening 30 is formed so as to cover the entire electroosmotic pump 16 and the space 25. Cover the insulating substrate 12. The material of the lid is preferably formed of a ceramic material, silicon, glass or resin. Although the lid is not always necessary, the aqueous solution in the space 25 is in the vicinity of the heater 28 in the atmosphere in order to escape the collected bubbles and remove them from the aqueous solution, with or without the lid. It must be exposed.

  As described above, the electroosmotic flow pump 16 in the liquid delivery device 11 shown in FIG. 1 is formed.

  In the present example, the electroosmotic pump 16 is described as being used for a microchemical chip, but is not limited thereto. That is, the electroosmotic flow pump 16 of the present invention can be used for liquid feeding other than the microchemical chip, for example, in a fuel cell.

  That is, the present invention is not limited to the embodiments described above, and various modifications can be made without departing from the scope of the present invention. That is, embodiments obtained by combining technical means appropriately deflected in addition to the gist of the present invention are also included in the technical scope of the present invention. For example, in the example of the embodiment described above, the structure in which the electroosmotic material 21 is arranged from the surface layer of the insulating base 12 is described. However, a space for embedding the electroosmotic material 21 is provided inside the insulating base 12. In addition, the electroosmotic pump 16 can be disposed inside the insulating base 12. By providing the electroosmotic pump 16 in the inner layer of the insulating substrate 12, when the type and amount of reagents and liquid to be fed increase and a complicated flow channel structure becomes necessary, the internal flow channel is added to provide the pump. An increase in size of the microchemical chip including the liquid device 11 or the fuel cell can be suppressed.

  Further, in the example of the embodiment described above, the electroosmotic material 21 is disposed in the through hole 32 (hole 22) formed so as to become the electroosmotic pump 16 after firing. By forming a fine flow path of 20 to 50 μm on the surface of each ceramic green sheet 31a to 31e on the surface of each of the ceramic green sheets 31a to 31e at a position corresponding to the through hole 32 of the sheets 31a to 31e, and laminating these, By forming the porous structure, it is possible to manufacture the liquid delivery device 11 in which the insulating base 12 and the electroosmotic material 21 are integrated. In this case, particularly when the electroosmotic pump 16 is disposed inside the insulating substrate 12, the electroosmotic material 21 moves in the space 25 due to the buoyancy applied by being in the aqueous solution to be fed, and the subsequent It is possible to prevent the hole of the flow path 14 from being blocked.

  Examples of the liquid delivery device of the present invention will be described below.

  First, a suitable organic binder and a solvent are mixed with aluminum oxide, dioctyl terephthalate as a plasticizer is added to form a slurry, and this is formed into a sheet shape by a doctor blade method, whereby a ceramic green sheet 31a to 130 μm in thickness is formed. 31e was formed.

  Next, through holes 33a serving as upstream flow paths and through holes 34a serving as downstream flow paths were formed in the ceramic green sheets 31a to 31e so as to have a flow path width of 1000 μm, respectively. Further, an electroosmotic material 21 to be described later was inserted, and a through hole 32 to be a hole 22 necessary for forming the space 25 was formed to have a dimension of 7 mm in the flow direction and 10 mm in the width direction of the flow.

  Further, the through-hole 33b serving as the upstream flow path and the through-hole 34b serving as the downstream flow path for forming the upstream flow path 23b and the downstream flow path 24b in the ceramic green sheets 31b and 31d, respectively, Was formed at two locations in the upstream region and the downstream region so that the channel length was 10 mm. These through holes were formed by punching with a mold.

  Next, platinum powder was used as the material for the metal powder, a binder and a solvent were added, and the mixture was stirred with a stirrer to prepare conductor pastes for the first and second electrodes.

  Next, ceramic green sheets 31a to 31g were laminated to form a laminate 40 of ceramic green sheets. At the time of lamination, an adhesion liquid was applied between the ceramic green sheets 31a to 31g, and lamination was performed by applying a load of 60 tons under vacuum conditions. Of the inner wall surfaces of the through holes 32 that become the holes 22 formed in the laminated body 40 of the laminated ceramic green sheets, the first and second electrodes 26 are provided on the inner wall surfaces 35 positioned on the upstream side and the downstream side of the flow path. End face electrodes 36 and 37 to be the first electrode 26 and the second electrode 27 were formed by end face printing of the conductive paste for 27.

  Next, among the inner wall surfaces of the through holes 32 formed in the laminated body 40 of the laminated ceramic green sheets, ruthenium oxide and an organic binder are formed on the inner wall surface 39 which is an inner wall surface parallel to the flow direction in the space 25. The end face electrode 38 to be the heater 28 was formed by end face printing of the conductive paste prepared by mixing the solvent and the solvent. The end face electrode 38 to be the heater 28 is formed on the inner wall surface 39 that is 2 mm away from the electroosmotic material 21 described later, and is close to the second electrode 27 that is the downstream electrode of the first electrode 26 and the second electrode 27. Formed on the side. The area of the printing region was formed in a range of 60% with respect to the entire area of the inner wall surface 39 parallel to the flow direction.

  Next, the ceramic green sheet laminate 40 was fired and sintered at about 1600 ° C. in a reducing atmosphere.

  Next, an electroosmotic material 21 made of a porous material of silica having an average pore diameter of 35 μm and a porosity of 70% was embedded in the hole 22 inside the sintered electroosmotic pump 16. . The electroosmotic material 21 was designed and installed so that a gap of 1000 μm was formed between the electroosmotic material 21 and the first and second electrodes 26 and 27 in the flow direction. In addition, the volume of the space 25 was designed and installed so as to be 20% with respect to the total volume of the hole 22.

  For the liquid delivery device 11 produced as described above, the electroosmotic pump 16 is operated to feed blood as an aqueous solution at a flow rate of 10 μL per second for 5 minutes, and an external application device is connected to the heater 28. A bubble collection test was performed by confirming the state of collection of bubbles when the voltage of the volt was applied to change the temperature of the heater 28. At this time, the temperature of the heater 28 is measured by connecting a thermocouple directly to the surface of the heater 28, set at intervals of 10 ° C. within the range of 40 to 110 ° C., and the test conditions 1 to 8, respectively. A collection test was conducted. As a method for confirming the state of collection of bubbles, the liquid level of the collection unit 15 located at the end of the flow path 14 was magnified 200 times with an optical microscope, and the presence or absence of bubbles in the collection unit 15 was confirmed. The results are shown in Table 1.

  In Table 1, if the sampling part 15 was able to remove most of the bubbles but did not reduce the liquid feeding efficiency, it could be confirmed that bubbles were confirmed by entering “△” in the “Bubble presence / absence” column of the table. In the case where bubbles were not confirmed in the sampling unit 15, “◯” was entered in the “bubble presence / absence” column in the table.

  As can be seen from the results shown in Table 1, bubbles were able to be removed so as to maintain good liquid feeding efficiency in any of the test conditions 1 to 8. In test condition 1 where the temperature of the heater 28 is lower than 50 ° C., bubbles were confirmed in the sampling part 15 although the liquid feeding efficiency was not lowered. (Indicated by “Δ” in the “Bubble presence / absence” column in the table). Further, even in the test conditions 6 to 8 where the temperature of the heater 28 is higher than 80 ° C., bubbles were confirmed in the sampling unit 15 although the liquid feeding efficiency was not greatly reduced. (Indicated by “Δ” in the “Bubble presence / absence” column in the table). And in the test conditions 2-5 whose temperature of the heater 28 is 50-80 degreeC, the bubble was not confirmed in the collection part 15, but the bubble was removed favorably ("In the presence or absence of a bubble" column in a table | surface, " ○ ”).

  From the above results, the liquid feeding device of the present invention can remove bubbles generated in the electrode in the aqueous solution in the electroosmotic flow pump and efficiently send the aqueous solution, and can cope with downsizing. It was confirmed to be useful as a liquid feeding device in a microchemical chip.

11: Liquid feeder
12: Insulation substrate
13: Supply department
14: Flow path
15: Collection unit
16: Electroosmotic flow pump
21: Electroosmotic material
22: Hole
23a, 23b: upstream flow path
24a, 24b: Downstream channel
25: Space
26: First electrode
27: Second electrode
28: Heater
29, 39: inner wall
30: Opening
31a-31g: Ceramic green sheet
32: Through hole to be a hole
33a, 33b: a through-hole serving as an upstream flow path
34a, 34b: Through holes that serve as downstream flow paths
35: Inner wall surface perpendicular to the flow path (located upstream and downstream)
36: End face electrode to be the first electrode
37: End face electrode to be the second electrode
38: End face electrode
40: Laminate of ceramic green sheets

Claims (3)

Provided in the middle of the flow path through which the aqueous solution formed on the insulating substrate flows, the first electrode on the upstream side and the second electrode on the downstream side of the electroosmotic material made of a porous body mainly composed of silica are provided. An electroosmotic flow pump is provided, and adjacent to the electroosmotic flow pump, there is provided a space in which the first electrode and the second electrode are not opposed and filled with the aqueous solution. the there from electroosmotic member at a position far opposed to the electroosmotic member, the inner wall surface parallel to the flow direction of the flow path of the space, a heater for heating is provided to the aqueous solution before Symbol space The liquid feeding device is characterized in that the heater is provided so as to be located on a side closer to the second electrode of the inner wall surface .   2. The liquid feeding device according to claim 1, wherein the electroosmotic material is contained in a facing space where the first electrode and the second electrode face each other.   The liquid feeding device according to claim 1, wherein the space has an opening for exposing the aqueous solution.

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