JP2004183495A - Micro hydraulic system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable the transfer of fluid with a simple structure where pumping is carried out for a plurality of passages with a single chamber, and to converge or diverge at a predetermined ratio. <P>SOLUTION: A micro hydraulic system 1 is comprised of a chamber 11, a piezoelectric element 34 for increasing and reducing the volume of the chamber, a plurality of passages 22, 23, and 24 connected to the chamber and openings 12, 13 and 14 set to throttle the passage at a plurality of the passages respectively, and formed to feed fluid by changing the ratio of a passage resistance between openings owing to the difference in a degree of a rate of change when increasing and decreasing the volume of the chamber. At least three passages are connected to the chamber as a plurality of the passages. At least one opening set in the passage is set so that the rate of change in passage resistance of the opening differs from another opening when the pressure in the chamber is increased or reduced. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a microfluidic system used for chemical analysis or the like that requires a very small amount of fluid to be sent with high precision.
[0002]
[Prior art]
2. Description of the Related Art In recent years, a μ-TAS (Micro Total Analysis System), which applies micromachine technology to miniaturize instruments and methods for chemical analysis and chemical synthesis, etc., has attracted attention. According to the miniaturized μ-TAS, there are advantages such as a smaller required amount of a sample, a shorter reaction time, and less waste compared to a conventional apparatus. Further, when used in the medical field, the burden on the patient can be reduced by reducing the amount of a sample such as blood, and the cost of the test can be reduced by reducing the amount of the reagent. Further, since the amounts of the sample and the reagent are small, the reaction time is greatly reduced, and the efficiency of the test can be improved. Because of its excellent portability, its application is expected in a wide range of fields such as the medical field and environmental analysis.
[0003]
Now, in chemical analysis, environmental measurement, and the like using a microfluidic system, a micropump may be used as a liquid sending means to perform liquid sending, mixing, and detection on a device (chip).
[0004]
As an example of a micropump suitable for such a liquid sending means, there is a valveless micropump disclosed in JP-A-2001-322099 disclosed by the present applicant. Next, this conventional valveless micropump will be described.
[0005]
FIG. 9 is a plan view schematically showing a configuration of a conventional micropump 80, and FIG. 10 is a front sectional view of the micropump 80.
9 and 10, the micropump 80 has a chamber 81, two openings 82 and 83 communicating with the chamber 81, and flow paths 84 and 85.
[0006]
As shown in FIG. 10, the micropump 80 is formed by etching a surface of a photosensitive glass substrate 91 to form a depression or a groove for forming a chamber 81 or the like. 92 are stacked. A portion of the glass substrate 92 facing the chamber 81 has a hole formed by etching or the like. A thin glass substrate 93 is further laminated on a glass substrate 92 to form a diaphragm, and a piezoelectric element 94 is adhered on the diaphragm. By deforming the diaphragm by the piezoelectric element 94, the volume of the chamber 81 changes.
[0007]
The flow path resistance of one opening 82 is low when the differential pressure at both ends thereof is close to zero, but the flow resistance increases as the differential pressure increases. That is, the pressure dependency is large. In the other opening 83, the flow path resistance when the differential pressure is close to zero is larger than that in the case of the opening 82, but there is almost no pressure dependency, and even when the differential pressure becomes large, the flow path resistance does not change much. However, when the differential pressure is large, the flow path resistance becomes smaller than that of the opening 82 (see FIG. 3).
[0008]
The chamber 81 is repeatedly pressurized / depressurized by utilizing such a difference between the flow path resistance characteristics of the opening 82 and the opening 83, and at this time, the ratio of the pressure change between pressurized and depressurized is appropriately adjusted. By controlling, it is possible to realize a pump action capable of arbitrarily changing the flow rate and the flow direction of the liquid.
[0009]
Such pressure control of the chamber 81 is realized by controlling the drive voltage supplied to the piezoelectric element 94 and controlling the amount and timing of the deformation of the diaphragm. For example, by applying a drive voltage having a waveform shown in FIG. 4A to the piezoelectric element 94, a liquid is ejected in the M1 direction in FIG. 10, and by applying a drive voltage having a waveform shown in FIG. Discharge in the opposite direction.
[0010]
By the way, when it is desired to combine two liquids using a micropump, it is general to prepare a micropump for each liquid, send out each liquid individually by each micropump, and merge them with a mixer. (JP-A-10-110681).
[0011]
Also, when one liquid is to be sent out to a plurality of different flow paths using a micro pump, a number of micro pumps corresponding to the number of flow paths are prepared, and the amount required for each flow path by each micro pump is prepared. It is common to send out each of the liquids.
[0012]
[Patent Document]
JP 2001-322099 A
JP-A-10-110681
[0013]
[Problems to be solved by the invention]
However, for example, when two liquids are mixed using two micro pumps, it is not easy to mix at a predetermined flow ratio due to the interaction between the micro pumps. In particular, when a valveless micropump is used, if the pump with the higher flow rate is strongly driven, a force for reverse flow acts on the flow path on the other pump side, and mixing at a desired flow rate ratio may occur. Have difficulty.
[0014]
In addition, a plurality of micropumps must be used for both mixing and split flow, and control must be performed for each of them, which causes a problem that the configuration is complicated.
[0015]
Furthermore, it is conceivable that mixing or splitting is performed at a desired flow ratio by providing a movable flow switching valve in the branch portion or providing an individual valve in each flow path. However, in this method, the structure is further complicated because various mechanisms for mechanical displacement are required. In addition, there is a problem that the flow rate is not stabilized due to foreign matter adhering to the valve, a problem of durability, and the like.
[0016]
SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problem, and a simple configuration in which a single chamber performs a pumping operation on a plurality of flow paths can stably send a fluid, and merge at a predetermined ratio. Alternatively, it is an object to provide a microfluidic system capable of diverting.
[0017]
[Means for Solving the Problems]
A microfluidic system according to the present invention is provided for reducing a flow path in each of the plurality of flow paths connected to the chamber, an actuator for increasing or decreasing the volume of the chamber, a plurality of flow paths connected to the chamber, and the plurality of flow paths. With a configuration in which the volume of the chamber is increased and decreased, the ratio of the change in flow rate is varied by changing the ratio of the flow path resistance between the openings, and the fluid is sent. Wherein at least three of the plurality of flow paths are connected to the chamber, and at least one of the openings provided in the flow path adjusts the pressure of the chamber. The rate of change in the flow path resistance of the opening when raised or lowered is set to be different from that of the other openings.
[0018]
Preferably, the change rates of the flow path resistance of at least three of the openings are set to be different from each other.
In at least one of the plurality of flow paths, the plurality of openings are provided in parallel to form an opening group, and the opening group is a flow path as a whole of the opening group. The change rate of the path resistance is set smaller than that of the openings of the other flow paths.
[0019]
In addition, one of the opening groups includes at least one opening having a uniform channel cross section, and the other opening group includes a channel corresponding to a cross-sectional area of each opening. Each of the openings has at least one opening whose length ratio is smaller than that of the opening having the uniform channel cross section.
[0020]
In such a microfluidic system, by controlling a drive voltage waveform applied to the actuator, the magnitude of the rate of change is different between when the volume of the chamber is increased and when the volume of the chamber is decreased. It is used so that the fluid is sent in a flow rate and a direction corresponding to the magnitude of the flow path resistance of the group of openings to cause the fluid to merge or split.
[0021]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 is a plan view schematically showing a configuration of a microfluidic system 1 according to a first embodiment of the present invention, FIG. 2 is a front sectional view of the microfluidic system 1 according to the first embodiment, and FIG. FIGS. 4 and 5 are diagrams showing examples of flow path resistance characteristics, FIGS. 4 and 5 are diagrams showing examples of driving voltage waveforms of the piezoelectric element, and FIG. 6 is a diagram showing how the volume of the chamber 11 changes due to the driving voltage. FIG. 2 is a diagram illustrating a cross-sectional view taken along a plane passing through the center of the flow path 22, the opening 12, the chamber 11, the opening 13, and the flow path 23 in FIG.
[0022]
As shown in FIGS. 1 and 2, the microfluidic system 1 includes a chamber 11 that is a pump chamber, first, second, and third three flow paths 22, 23, and 24 connected to the chamber 11. Each of the channels 22, 23, and 24 has first, second, and third openings 12, 13, and 14 provided to narrow the channels.
[0023]
As shown in FIG. 2, the microfluidic system 1 uses the silicon substrate 31 to form the chamber 11, the openings 12, 13, 14, and the flow paths 22, 23, 24 by a photolithography process. And a glass substrate 32 serving as a bottom plate is bonded thereunder. At this time, the hollow serving as the chamber 11 in the silicon substrate 31 is dug by half etching so that the silicon substrate 31 does not penetrate, and the remaining portion of the silicon substrate 31 is used as a diaphragm 31f. The piezoelectric element 34 is stuck on the diaphragm 31f.
[0024]
The microfluidic system 1 can be manufactured in this way, but can also be manufactured using a conventionally known method, another method, or another material.
[0025]
As the piezoelectric element 34, for example, a thin plate of PZT (lead zirconate titanate) ceramic is used. Two electrodes for driving the piezoelectric element 34 are drawn out on the surfaces on both sides of the piezoelectric element 34, wired by a flexible cable 35 and the like, and connected to the drive circuit 36.
[0026]
By applying a voltage having a waveform shown in FIG. 4A or FIG. 5A to the piezoelectric element 34 by the drive circuit 36, the diaphragm 31f, which is a silicon thin film, and the piezoelectric element 34 undergo unimorph mode bending deformation. Using this, the volume of the chamber 11 is increased or decreased.
[0027]
For example, as shown in FIG. 6, when a driving voltage of a triangular wave is used for simplification, the volume of the chamber 11 changes according to the waveform.
In the present embodiment, the first, second, and third openings 12, 13, and 14 are configured such that the change rates of the flow path resistance when the pressure in the chamber 11 is increased or decreased are different from each other. Is set to Then, the rate of change is such that the first opening 12 is the largest, the second opening 13 is smaller than the first opening, the second opening, and the third opening. The part 14 is set smaller.
[0028]
That is, as shown in FIG. 3, the first opening 12 has a low flow path resistance when the differential pressure at both ends thereof is close to zero, but increases as the differential pressure increases. That is, the pressure dependency is large. The third opening 14 has a large flow path resistance when the differential pressure is close to zero, but has little pressure dependence, and the flow resistance is slightly increased even when the differential pressure increases. The pressure dependency of the flow path resistance of the second opening 13 is intermediate between the first opening 12 and the third opening 14.
[0029]
Such a flow path resistance characteristic is such that the fluid flowing in the flow path, for example, a liquid, is either laminar or turbulent depending on the magnitude of the differential pressure, or is always laminar regardless of the differential pressure. Or can be obtained by: That is, basically, the first, second, and third openings 12, 13, and 14 may be formed in such a shape that the laminar flow develops sufficiently and turbulence hardly occurs.
[0030]
Specifically, for example, the first opening 12 is an orifice having a short flow path length, the third opening 14 is a nozzle having a long flow path length, and the second opening 13 is an intermediate length thereof. This can be achieved by:
[0031]
From another viewpoint, each of the openings 12, 13, and 14 has a uniform flow path cross section, and the ratio of the flow path length to the cross sectional area increases in the first, second, and third order. What is necessary is just to set it so that it may be set, and it may be made into the dimension shape which has the area | region where the flow path resistance value of each opening reverses mutually within the range of the differential pressure actually used.
[0032]
Therefore, for example, paying attention to the first opening 12 and the second opening 14, the pressure of the chamber 11 is increased, and if the rate of the change is increased, the differential pressure is increased, and the pressure of the opening 12 is increased. The flow path resistance becomes larger than the flow path resistance of the opening 14, and most of the fluid in the chamber 11 is discharged from the opening 14. When the pressure in the chamber 11 is lowered and the rate of the change is reduced, the differential pressure is kept small, and the flow resistance of the opening 12 becomes smaller than the flow resistance of the opening 14. More fluid flows into chamber 11 from section 12.
[0033]
Conversely, if the pressure in the chamber 11 is increased and the rate of the change is reduced, the differential pressure is kept small, and the flow resistance of the opening 12 becomes smaller than that of the opening 14. And the fluid in the chamber 11 is discharged more from the opening 12. When the pressure in the chamber 11 is lowered and the rate of change is increased, the differential pressure increases, and the flow resistance of the opening 12 becomes larger than the flow resistance of the opening 14. From 14, more fluid flows into the chamber 11.
[0034]
Such pressure control of the chamber 11 is realized by controlling the drive voltage supplied to the piezoelectric element 34 and controlling the amount and timing of the deformation of the diaphragm. For example, by applying a driving voltage having a waveform shown in FIG. 4A to the piezoelectric element 34, the liquid is ejected to the flow channel 24 side, and by applying a driving voltage having a waveform shown in FIG. To the side of.
[0035]
4 and 5, the maximum voltage e1 applied to the piezoelectric element 34 is about several volts to several tens of volts, and is about 100 volts at the maximum. As an example of the time, the times T1 and T7 are about 20 μs, the times T2 and T6 are about 0 to several μs, and the times T3 and T5 are about 60 μs. Times T4 and T8 may be zero. The frequency of the driving voltage is about 11 KHz. The flow rates shown in FIGS. 4B and 5B are obtained in the flow path 24 by the driving voltages shown in FIGS. 4A and 5A. The flow curves in FIGS. 4 (B) and 5 (B) schematically show the flow obtained by the pump operation, and the inertial vibration of the fluid is actually superimposed. Therefore, a curve in which the vibration component is superimposed on the flow rate curve shown in these figures indicates the actually obtained flow rate.
[0036]
However, the actual flow of the fluid is further complicated since the second opening 13 participates in this as discharge or suction.
Therefore, by utilizing such flow path resistance characteristics of the openings 12, 13, and 14, a pressure is generated in the chamber 11 and the rate of change of the pressure is controlled, whereby each opening at that time is controlled. Liquids can be sent in flow rates and directions according to the magnitudes of the flow path resistances of 12, 13, and 14, so that fluids can be merged or split.
[0037]
For example, as shown in FIGS. 4 and 5, at least two types of drive voltage waveforms are prepared and switched. Further, the maximum voltage e1 may be different even if the waveforms are the same. Further, it is possible to arbitrarily change the waveform and the maximum voltage e1 to finely adjust the discharge direction, flow rate, flow rate ratio, and the like.
[0038]
When fluids from a plurality of flow paths are merged in the chamber 11, they can function as, for example, a mixer. When the fluid is discharged from the chamber 11 to the plurality of flow paths, the pump can function as a pump that discharges the plurality of flow paths at a predetermined ratio, or can function as a flow divider or a flow path switch.
[0039]
As shown in FIG. 3, it is more effective to set the flow path resistance characteristic curves of these three openings 12, 13, and 14 so as to intersect each other within the range of the differential pressure to be used. This is because the flow efficiency can be improved by reversing the magnitude relationship between the flow path resistances when the absolute value of the differential pressure is larger and smaller than the differential pressure at the point where each curve intersects. is there. As described above, the reversal of the magnitude relation of the flow path resistance is not always necessary to satisfy the basic function as the microfluidic system 1, but is an important factor for improving the flow rate efficiency.
[0040]
In FIG. 3, the three curves do not intersect at one point, and the order of the flow path resistance of the three openings 12, 13, and 14 changes within a certain range. By appropriately setting the change of the flow path resistance characteristic in this way, it is possible to further enhance the various functions described above.
[0041]
Next, specific examples of the dimensions of each part will be described.
The opening 12 has a width of about 25 μm and a length of about 25 μm. The opening 13 has a width of about 30 μm and a length of about 90 μm. The opening 14 has a width of about 36 μm and a length of about 180 μm. Each of the openings 12, 13, and 14 has a depth of about 25 μm, and has a uniform cross-sectional shape (flow-path cross section) in the longitudinal direction of the flow path (the direction in which the fluid flows).
[0042]
At this time, the value of L / S, that is, the value of [flow path length / cross-sectional area] (unit: μm ⁻¹ ) is 0.04 for opening 12, 0.12 for opening 13, and 14 for opening 14. Is 0.20. That is, the value of [flow path length / cross-sectional area] increases in the order of the first opening 12, the second opening 13, and the third opening 14.
[0043]
L used here is the flow path length of the opening. However, depending on the shape of both ends of the opening, there is a case where it is unclear where the length should be L. In that case, experiments may be performed on openings having various shapes, and an equivalent flow path length may be used as the effective flow path length based on the experimental results. The same applies to the sectional area S.
[0044]
The flow paths 22, 23, and 24 may be literally flow paths through which a fluid flows and guided to a predetermined position, or may be a chamber for giving some reaction to the fluid. It may be something like a reservoir that stores fluid. In this specification, these are collectively referred to as “flow paths”.
[0045]
According to the microfluidic system 1 described above, a single chamber 11 can perform a pumping action on a plurality of flow paths 22, 23, and 24, and discharge or suction into each of the flow paths 22, 23, and 24. Flow and direction can be controlled. Since only one chamber 11 and one piezoelectric element 34 for changing the capacity of the chamber 11 are required, the configuration is simple, the control is easy, and stable liquid feeding can be performed. By appropriately setting the flow path resistance characteristics of each of the openings 12, 13, and 14, and controlling the drive voltage applied to the piezoelectric element 34, a plurality of types of fluids are merged or separated at a predetermined ratio. Can be.
[0046]
In the above-described embodiment, a driving voltage having a triangular waveform or a substantially triangular waveform is applied to the piezoelectric element 34, but driving voltages having other various waveforms can be used. In short, it is sufficient if the absolute value of the velocity can be changed in a state where the speed of the vibration for increasing or decreasing the volume of the chamber 11 is made different between the rising time and the falling time.
[0047]
Next, a microfluidic system 1B according to a second embodiment will be described.
FIG. 7 is a plan view schematically showing the configuration of the microfluidic system 1B according to the second embodiment of the present invention.
[0048]
In the second embodiment, portions having the same functions as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted or simplified.
In the second embodiment, the second flow path 23 is provided with an opening group 13B including two openings 13a and 13b connected in parallel to each other, and the third flow path 24 is connected in parallel to each other. An opening group 14B including three opening portions 14a, 14b, and 14c is provided.
[0049]
That is, the opening group 13B includes two openings 13a and 13b, but the openings 13a and 13b have the same length, cross-sectional shape, and effective cross-sectional area. Further, as compared with the openings 13 shown in FIG. 1, the flow path lengths are twice as large, and the effective cross-sectional areas are all equal. In this case, the average flow resistance of the entire opening group 13B is substantially the same as that of the opening 13, but the change rate of the flow resistance of the entire opening group 13B is reduced, and the pressure-dependent Is reduced.
[0050]
The opening group 14B includes three openings 14a, 14b, and 14c. The openings 14a, 14b, and 14c have the same length, cross-sectional shape, and effective cross-sectional area. In addition, as compared with the openings 14 shown in FIG. 1, the flow path length is three times as large, and the effective cross-sectional areas are all equal. By doing so, the average flow resistance of the entire opening group 14B is substantially the same as that of the opening 14, but the rate of change of the flow resistance of the entire opening group 14B is reduced, and the pressure-dependent The characteristics are further reduced than in the case of the opening group 13B.
[0051]
For example, when a plurality of openings are arranged in parallel so as not to interfere with each other, the reciprocals of the flow path resistances of the individual openings are added, and the value obtained by taking the reciprocal is the total value of the opening group. It can be used as a channel resistance.
[0052]
At least one (all in this embodiment) of the openings 14 a, 14 b, 14 c provided in the third flow path 24 is the opening 12 or the opening provided in the other flow paths 22, 23. The value of [flow path length / cross-sectional area] is larger than any of 13a and 13b.
[0053]
Further, at least one (all in this embodiment) of the openings 13a and 13b provided in the second flow path 23 is larger than any of the openings 14a, 14b and 14c provided in the flow path 24. The value of [flow path length / cross-sectional area] is small.
[0054]
As described above, by narrowing the flow path using the opening groups 13B and 14B formed by the plurality of openings connected in parallel with each other, the overall pressure dependence of the opening groups 13B and 14B is reduced. As a result, the difference in pressure dependency between other openings or groups of openings is increased, and the flow characteristics of the pump can be improved.
[0055]
Next, the behavior of the fluid when the microfluidic system 1 is driven will be described.
FIG. 8 is a table showing the flow path resistance characteristics, the flow rate ratio, and the discharge amount per operation for each of the openings 12, 13, and 14 in the microfluidic system 1.
[0056]
Here, suppose that the flow path resistance values of the openings 12, 13, and 14 with respect to the chamber internal pressure when the volume of the chamber 11 is reduced are R1r, R2r, and R3r, respectively, and the flow paths 22, 23, and The volumes of the fluid entering and exiting 24 are V1r, V2r, and V3r, respectively.
[0057]
The flow path resistance values of the respective openings with respect to the chamber internal pressure when the volume of the chamber 11 increases are R1f, R2f, and R3f, respectively, and the volumes of the fluid flowing in and out of the flow paths at that time are V1f, V2f and V3f.
[0058]
In addition, the amount of change (width of vibration) of the volume of the chamber 11 is defined as V0.
At this time, the volume ΔV1 of the fluid sent out through the first flow path 22 in one reciprocation of the volume increase / decrease vibration of the chamber 11, for example, is approximately expressed by the following equation (actually, the inertia of the liquid is It is slightly different due to vibration.)
[0059]
ΔV1 = V1r−V1f
V1r = V0 × (1 / R1r) / [(1 / R1r) + (1 / R2r) + (1 / R3r)]
V1f = V0 × (1 / R1f) / [(1 / R1f) + (1 / R2f) + (1 / R3f)]
Similarly, for the second flow path 23 and the third flow path 24, the volume of the fluid sent out in one reciprocation of the volume increase / decrease vibration of the chamber 11 can be calculated.
[0060]
Here, when the flow path resistance characteristics of each opening are as shown in FIG. 8 (A), from the above equation, the volume of fluid sent out through each flow path in one reciprocation of the volume increase / decrease vibration of the chamber 11 is obtained. Is as shown in FIG.
[0061]
In the table of FIG. 8C, a plus number indicates a discharge direction, and a minus number indicates a suction direction. As can be seen from the table in FIG. 8C, the flow ratio to each opening and its direction can be switched by making the driving pattern of the chamber 11 different.
[0062]
Furthermore, if the pressure accompanying the increase or decrease in the volume of the chamber 11 is controlled by finely adjusting the rise time or fall time of the drive voltage waveform, for example, it is possible to finely adjust the flow rate and the flow rate ratio.
[0063]
In the above-described embodiment, the number of channels is three, but may be four or more. Further, any of the flow paths may have an opening group including a plurality of openings. Further, the group of openings provided in the flow path may be composed of four or more openings.
[0064]
In the embodiment described above, the flow paths 22, 23, and 24 may be used as flow paths of the circulation system. Further, the respective flow paths 22, 23, and 24 may be configured to merge at a position away from the chamber 11. Even in that case, they may be handled not as one flow path but as flow paths connected to the respective chambers 11.
[0065]
In the embodiment described above, the example in which the microfluidic systems 1 and 1B are manufactured using the silicon substrate has been described, but a material such as resin, glass, metal, and ceramic may be finely processed. Instead of forming the diaphragm 31f by half etching, it may be formed by laminating a separately prepared thin plate. In this case, any material may be used, but care must be taken since sufficient displacement characteristics may not be obtained if the material is extremely softer than the piezoelectric element.
[0066]
In the above-described embodiment, the depth of the chamber 11 is the same as the depth of the opening. However, the depth need not be the same, and may be deeper or shallower. The deformation of the piezoelectric element 34, which is an actuator for increasing or decreasing the volume of the chamber 11, is not necessarily a unimorph bending deformation, but may be, for example, a longitudinal vibration, a lateral vibration, a shear deformation vibration, or the like. The actuator is not limited to the piezoelectric element 34, but may be any actuator that can increase or decrease the volume of the chamber 11, such as an electrostatic actuator, an electromagnetic actuator, or a shape memory alloy. Further, the actuator may not be integrated with the microfluidic system 1 but may be separately detachable.
[0067]
Regarding the shape of the opening, it is not always necessary that the cross section of the flow path is completely uniform even though it is uniform. Further, it is not always necessary to have a uniform cross-sectional shape. For example, the inner surface may have some unevenness or taper. In such a case, the effective area or effective area S can be obtained based on experimental values or calculated values. In the vicinity of the entrance of the opening, particularly in the opening on the side serving as the discharge port (outlet), a slightly expanding portion or a smoothly expanding radius portion may be provided. In particular, in the opening on the side serving as the suction port (inlet), the function is not largely changed even if it does not have a uniform sectional shape. The fluid to be applied may be a liquid, a fluid, a gas, or the like.
[0068]
In the various embodiments and modifications described above, the planar shape of the microfluidic system 1 and 1B can be a square, a rectangle, a polygon, a circle, an ellipse, or other various shapes. In addition, the structure, shape, size, number, material, and the like of the whole or each part of the microfluidic system can be appropriately changed in accordance with the gist of the present invention.
[0069]
The microfluidic system according to the present invention can be used in various fields such as environment, food, biochemistry, immunology, hematology, gene analysis, synthesis and drug discovery.
[0070]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, the fluid can be sent stably by the simple structure of making a several chamber perform the pump action by one chamber. Further, a plurality of fluids can be combined or separated at a predetermined ratio.
[Brief description of the drawings]
FIG. 1 is a plan view schematically showing a configuration of a microfluidic system according to a first embodiment of the present invention.
FIG. 2 is a front sectional view of the microfluidic system according to the first embodiment.
FIG. 3 is a diagram illustrating an example of a flow path resistance characteristic of an opening.
FIG. 4 is a diagram showing an example of a waveform of a driving voltage of a piezoelectric element.
FIG. 5 is a diagram illustrating an example of a waveform of a drive voltage of a piezoelectric element.
FIG. 6 is a diagram showing how the volume of a chamber changes according to a drive voltage.
FIG. 7 is a plan view schematically showing a configuration of a microfluidic system according to a second embodiment of the present invention.
FIG. 8 is a diagram illustrating an example of a flow path resistance characteristic, a flow rate ratio, and a discharge amount per discharge for each opening.
FIG. 9 is a plan view schematically showing a configuration of a conventional micropump.
FIG. 10 is a front sectional view of a conventional micropump.
[Explanation of symbols]
1,1B Microfluidic system 11 Chambers 12, 13, 14 Openings 13B, 14B Openings (openings)
13a, 13b Openings 14a, 14b, 14c Openings 22, 23, 24 Channel 34 Piezoelectric element (actuator)

Claims (5)

A chamber, an actuator for increasing / decreasing the volume of the chamber, a plurality of flow paths connected to the chamber, and an opening provided for narrowing a flow path in each of the plurality of flow paths, A microfluidic system configured to send a fluid by changing the ratio of the flow path resistance between the openings by changing the magnitude of the rate of change between when the volume of the chamber increases and when the volume of the chamber decreases,
At least three flow paths are connected to the chamber as the plurality of flow paths,
At least one of the openings provided in the flow path is set so that the rate of change in the flow path resistance of the opening when the pressure in the chamber is increased or decreased is different from that of the other openings. Have been
A microfluidic system, characterized in that: The change rates of the flow path resistance of at least three of the openings are set to be different from each other,
The microfluidic system according to claim 1. In at least one flow path of the plurality of flow paths, a plurality of the openings are provided in parallel to form an opening group,
The opening group, the rate of change of the flow path resistance as a whole of the opening group is set smaller than that of the opening of the other flow path,
The microfluidic system according to claim 1. One of the opening groups includes at least one opening having a uniform channel cross section,
And, in the other group of openings, the ratio of the flow path length to the cross-sectional area of each opening includes at least one opening each smaller than that of the opening where the flow path cross section is uniform,
The microfluidic system according to claim 3. By controlling the drive voltage waveform applied to the actuator, the magnitude of the rate of change is different between when the volume of the chamber is increased and when the volume of the chamber is decreased, whereby the flow path resistance of each opening or the opening group is changed. Sending fluid in a flow rate and direction according to the size to cause the fluid to merge or split,
A method for using the microfluidic system according to any one of claims 1 to 4.

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