JP3531027B2 - Micro pumps and pump systems - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a trace amount fluid supply device for use in medical treatment, chemical analysis and the like, and more particularly to a micro pump structure for controlling a fluid flow rate with high accuracy and a pump system using this micro pump. .

[0002]

2. Description of the Related Art Conventionally, there are many principles in a pump for feeding a minute amount of liquid, but as a valveless pump utilizing the resistance of fluid as in the present invention, for example, Micro E
lectroMechanical Systems (1996) pp.378-383
Page, and Micro Electro Mechanical Systems
(1996) pp. 479-484. In both methods, two chambers and diffusers or nozzles having different opening angles connected to the chambers are processed on one plane of the silicon substrate by anisotropic etching or dry etching, and then the silicon substrate is etched. The pumped surface is formed by anodic bonding the surface on the side of the glass substrate with the glass substrate. On the suction side of the pump, a flow channel whose flow channel width increases toward the pump is formed, and on the discharge side, a flow channel whose flow channel width decreases toward the pump.

The pump delivers liquid by alternately moving (oscillating) the diaphragms forming the wall surfaces of the two chambers, which are independently formed in parallel, in opposite phases. At this time, a bimorph type piezoelectric disk is used to drive (vibrate) the diaphragm. There are two chambers to reduce pulsation.

The operating principle of the pump is as follows. When the diaphragm is displaced downwards, that is, when the volume of the chamber is reduced and the fluid in the chamber is pushed outward, the inlet side of the chamber functions as a nozzle and the outlet side of the chamber functions as a diffuser. The fluid resistance on the inlet side is larger than that on the side, and the amount of liquid flowing out of the diffuser on the outlet side is larger than the amount of liquid flowing out from the inlet side. On the other hand, when the diaphragm is displaced upward, that is, when the volume of the chamber increases and the pressure inside the chamber decreases and the external fluid flows into the chamber, the outlet side of the chamber functions as a nozzle. Since the inlet side functions as a diffuser, the fluid resistance on the outlet side becomes larger than that on the inlet side, and the amount of liquid flowing from the inlet side is larger than the amount of liquid flowing from the outlet side. Therefore, the liquid flows in the direction of the diffuser as a whole. The role of the diffuser is to convert the flow velocity into discharge pressure. The width of the diffuser inlet is 20-80 micrometers. Further, it is described that the optimum angle of the diffuser is 2θ = 4 degrees.

[0005]

In the prior art, the efficiency of the diffuser and the efficiency of the nozzle largely change depending on the angle of the diffuser or the nozzle, and a region where the efficiency of the diffuser is higher than that of the nozzle is used to increase the pressure. However, the area is narrow, and the optimum angle is 2θ = 4 degrees as described above. Further, since the proper size ratio of the inlet and the outlet of the diffuser or nozzle is small and the optimum angle of the diffuser or nozzle is small as described above, the size of the diffuser or nozzle is designed to be small. Therefore, the processing accuracy may directly affect the performance. Further, in the above-mentioned pump, the flow velocity at the fluid resistance portion is high, so that cavitation is likely to occur. Therefore, there is a problem that the drive frequency of the pump can be changed only in the region where cavitation does not occur.

An object of the present invention is to make the structure of the micropump a structure that has a small influence on the pump performance even if the processing accuracy is low.

[0007]

Means for Solving the Problems The present invention, in order to solve the above problems, at least a portion vibrates in the thickness direction <br/> Daiafura arm pressure chamber made form with at least a portion of the wall To the fluid inlet and to the inlet of the pressure chamber.
The flow path or chamber connected to the mouth side and the outlet side of the pressure chamber
It and a chamber connected to the outlet of the fluid with lead, before Kida diaphragm and alter the volume of the pressure chamber by vibrating the fluid resistance when handling fluid flows into the pressure chamber by the volume change by utilizing the difference in fluid resistance when the flowing out of the pressure chamber a valveless micro pump for discharging the fluid, the inlet side of the pressure chamber,
And the inlet side of the chamber leading to the outlet side of the pressure chamber, each
S, in the die A Fram plane parallel to surface of the pressure chamber
Form a shape that is symmetrical with respect to the center line of the pressure chamber toward the inside.
And formed to extend in parallel to the direction of fluid flow
Inside the pair of protrusions and the chamber connected to the outlet side of the pressure chamber
Toward the center of the pressure chamber with respect to the center line of the pressure chamber.
Characterized in that the structure provided with <br/> pair of collision force formed in a shape extending parallel to the direction in which fluid flows to. By using a structure like this, it is not necessary to use a diffuser or nozzle as the conventional method. Therefore, it is not necessary to obtain the proper angle and the dimensional ratio of the inlet and the outlet, and the processing accuracy does not directly affect the performance. Further, in this method, since there is no portion where the flow velocity sharply rises in the fluid resistance portion, cavitation does not easily occur even if the drive frequency of the pump is increased. Also, the diaphragm is formed
The first substrate that has been formed
And a second substrate arranged as follows.
A flow path or chamber connected to the inlet side of the pressure chamber, and the pressure
A hollow that becomes a chamber connected to the force chamber and the outlet side of the pressure chamber.
And a pair of members formed toward the inside of the pressure chamber.
Toward the inside of the projection and the chamber connected to the outlet side of the pressure chamber
And a pair of protrusions formed by
It

In addition, the pressure chambers of the micropump of the present invention are arranged in series, or the micropumps of the present invention are arranged in parallel with one inlet and one outlet, and the driving of each substrate is controlled to control the pressure. It is possible to obtain a wide range of flow rates.

In order to process the substrate to form the pressure chamber, the substrate may be a silicon substrate and may be formed by anisotropic etching or dry etching of silicon.

Further , the first substrate of the second substrate
The third substrate is placed in contact with the surface opposite to the surface in contact with
Contact the surface of the third substrate opposite to the second substrate.
And a fourth substrate is arranged, and the third substrate and the fourth substrate are arranged.
Between the plates, a micro flow path leading to the inlet and the outlet
May be formed .

Further, a plurality of storage tanks for storing different liquids, a plurality of micropumps whose suction sides are connected to the storage tanks via filters, and a discharge side of the plurality of micropumps are connected to each other via a mixer. And a micropump system comprising:
The micro pump may be the micro pump according to any one of claims 1 to 5.

[0012]

1 is a block diagram of an embodiment of the present invention.
It will be described with reference to FIGS. The structure of the micropump according to the first embodiment of the present invention will be described with reference to FIG. FIG. 1 (a) shows a cross-sectional view of the pump, and FIG. 1 (b) shows a plan view of the pump. As shown in FIG. 1A, the micropump of the present embodiment is arranged so as to be bonded to the first substrate 1 on which the diaphragm 8 is formed and the surface of the first substrate 1 on which the diaphragm is formed. A second substrate 2 and a actuator 7 which is arranged so as to be bonded to the diaphragm of the first substrate 1 and vibrates the diaphragm 8 in the vertical direction in the figure (direction perpendicular to the substrate surface). Has been done.

A pressure chamber 3 is formed in the second substrate 2 at a position facing the first substrate 1 and facing the diaphragm 8 and having a recessed indentation of a uniform depth from the substrate surface. The first chamber 9 is formed on the left side of the pressure chamber 3 in the drawing, and the second chamber 10 is formed on the right side of the pressure chamber 3 in the drawing at the same depth as the pressure chamber 3. The first chamber 9 and the pressure chamber 3 are the pressure chamber 3
Is connected by a nozzle 11 having a narrower channel width toward the second chamber 10. The pressure chamber 3 and the second chamber 10 are connected by a nozzle 11A having a narrower channel width toward the second chamber 10. Nozzle 1
The depth of engraving of the nozzle 1 and the nozzle 11A from the substrate surface is the same as that of the pressure chamber 3. Further, an inlet 4 which is a flow path opening to the surface of the second substrate 2 opposite to the first substrate 1 is connected to the end of the first chamber 9 far from the pressure chamber 3, At the end of the second chamber 10 on the side far from the pressure chamber 3,
An outlet 5 that is a flow path that opens to the surface of the second substrate 2 opposite to the first substrate 1 is connected. That is, the inlet 4 communicates with the pressure chamber 3 through the first chamber 9 and the nozzle 11, and the pressure chamber 3 communicates with the outlet 5 through the nozzle 11A and the second chamber 10.

Processing for forming the diaphragm 8 on the first substrate and the pressure chamber 3, the first chamber 9, and the second substrate on the second substrate.
The chamber 10, the nozzles 11 and 11A, the inlet 4, and the outlet 5 are processed by the photolithography process used for manufacturing a semiconductor and anisotropic etching of silicon. More specifically, both the first substrate and the second substrate are 3 inches (10
0) A silicon wafer having a thickness of 220 μm was used.
As long as the silicon wafer is thicker than 220 μm or thinner than 220 μm, there is no problem in strength as a micropump.

The processing process of the first substrate is as follows. First, a thermal oxide film 6 having a thickness of about 1.5 μm is formed on both surfaces of a silicon wafer, and the mask pattern of the diaphragm is transferred onto one surface by photolithography. Next, the thermal oxide film 6 with the transferred pattern
With a mask of 40 wt% potassium hydroxide aqueous solution (67
C.) is used for anisotropic etching of silicon.
Anisotropic etching is a crystal surface of silicon, for example,
Etching rate is 1: for (111) plane and other crystal planes.
The structure is processed by utilizing the difference of about 200. In FIG. 1A, the central portion of the diaphragm 8 remains without being etched, but this is a portion to be joined to the actuator 7 that vibrates the diaphragm.

The processing process of the second substrate is as follows. First, a thermal oxide film 6 having a thickness of about 0.5 μm is formed on both surfaces of a silicon wafer, and the pressure chamber 3 and the flow path (the first chamber 9, the nozzle 11, the second chamber 11 and the second chamber) are formed there by photolithography. The mask pattern of the chamber 10 and the nozzle 11A) is transferred to one side. Next, using the thermal oxide film 6 with the transferred pattern as a mask, anisotropic etching of silicon is performed using a 40 wt% potassium hydroxide aqueous solution (67 ° C.) to form a pressure chamber having a depth of 15 μm from the substrate surface. Form a flow path. After that, a thermal oxide film 6 is again formed to a thickness of 1.5 μm on both surfaces of the silicon wafer, and an inlet and outlet mask pattern is formed on the surface where the pressure chamber is not formed by photolithography technology. Transcribe. Next, using the thermal oxide film on which the pattern was transferred as a mask, anisotropic etching of silicon was performed using a 40 wt% potassium hydroxide aqueous solution (67 ° C.), and the flow paths for the inlet 4 and the outlet 5 were formed in the wafer. Formed.

In the micropump of this embodiment, either a compressive fluid such as gas or an incompressible fluid such as water can be used as the fluid. In that case, when using a compressible fluid, the depth of the pressure chamber (the engraving depth from the substrate surface, the same applies below) need only be processed by the amount of displacement of the diaphragm. It functions as a pump even if the pressure chamber is deeply machined. Note that the pressure chamber and the inlet and outlet flow paths connecting to the pressure chamber may be formed not only in the second substrate but also in the first substrate. In addition, since this pump is a valveless pump, there is no concern that particles, etc. in the liquid will be caught in the valve due to the small movement amount of the valve, which has occurred in conventional valves or check valves. .

Silicon is directly bonded to the first substrate and the second substrate through a silicon thermal oxide film 6.
The direct bonding is a bonding method in which silicon wafers that have been cleaned in a clean atmosphere of class 10 are bonded to each other by hydrogen bonding and then high-temperature heat treatment is performed without pressure. For the first and second substrates of the micropump of the present invention, the thermal oxide film 6 formed on each of the first substrate and the second substrate was used to clean the bonding surfaces of the two substrates and then class 10
In the atmosphere described above, the substrates were bonded together by high-temperature heat treatment at 1150 ° C. for 2 hours to bond them. Also, the alignment required for assembly was performed outside the chip using a jig. As another alignment method, for example, a method of forming a marker on a wafer and performing alignment with a wafer size or a chip size using a deflection microscope or an infrared microscope may be used.

The bonding of the first substrate and the second substrate is not limited to direct bonding, and other bonding methods such as gold-silicon eutectic bonding and surface bonding are performed by forming a thin gold film on the surface and heating. Form a thin film of aluminum on and heat it,
Aluminum-silicon eutectic bonding, diffusion bonding in which a metal is sandwiched between bonding surfaces to make use of diffusion, and surface activation bonding in which bonding is performed while activating the bonding surface in vacuum using an ion beam or atom beam. Even if it is applied, it does not affect the function of the pump.

An actuator 7 is joined to the diaphragm 8 of the first substrate 1 in order to vibrate the diaphragm up and down. In this embodiment, a laminated piezoelectric element is used as the actuator 7. The upper part of the actuator is fixed by a jig so that only the diaphragm part of the pump is movable.

The method for driving or vibrating the diaphragm of the micropump of this embodiment is not limited to the piezoelectric element, and a method using magnetic force using a permanent magnet and an electromagnet, a method using electrostatic force, etc. may be used. You can

The second substrate 2 is used with reference to the plan view of FIG.
The structure of the structure formed in the above will be described. This plan view is a view of the second substrate 2 viewed from above in the drawing of FIG. 1A, that is, from the vibration direction of the diaphragm 8, in other words, from the direction perpendicular to the substrate surface. An inlet 4 and an outlet 5 are arranged on a silicon substrate (second substrate), and a pressure chamber 3 connected to them by a flow path is arranged. A first chamber 9 is provided on the inlet side of the pressure chamber 3 and a second chamber 10 is provided on the outlet side thereof. The second chamber 10 is provided on the outlet side of the pressure chamber 3 where the fluid is discharged.
A nozzle 11A connected to the second chamber 10 is arranged, and a pair of protrusions 12A is formed on the inlet side of the second chamber 10. Further, a nozzle 11 connected to the inlet side of the pressure chamber 3 is arranged on the outlet side of the first chamber 9, and a pair of protrusions 12 is formed on the inlet side of the pressure chamber 3.

When the shape of the projection 12 is projected perpendicularly to a plane parallel to the diaphragm 8, the nozzle 11 is moved to the pressure chamber 3
To the inside of the pressure chamber 3 in parallel to the center line of the nozzle 11 and symmetrically with respect to the center line of the nozzle 11 on both side surfaces of the flow path at the position (the position where the width of the nozzle is the narrowest). The distal end portion is in the shape of an arrow and is pointed so as to be closer to the first chamber 9 side as the distance from the center line of the nozzle 11 increases. Similarly,
The projections 12A are formed on both side surfaces of the flow path at a position where the nozzle 11A is connected to the second chamber 10 (position where the flow path width of the nozzle is the narrowest) toward the inside of the second chamber 10 in parallel with the center line of the nozzle 11A. Further, the nozzle 11A is formed in a shape that extends symmetrically with respect to the center line of the nozzle 11A, and the tip end thereof has a pointed shape that is inclined so as to approach the pressure chamber 3 side as the distance from the center line of the nozzle 11A increases. It has become. Protrusion 12, 12A
Is formed by etching the pressure chamber 3 and the second chamber 10 and leaving the substrate surface as it is without etching. The left end face (upstream end face) is projected toward the downstream side.

Further, in the present invention, a good range for changing the volume of the pressure chamber by the diaphragm is the dotted line portion 14 in FIG. 1B, that is, the portion excluding the portion where the protrusion 12 is present.

The pump principle of the present invention is shown in FIG. In the following description, for the sake of convenience, the diaphragm 8 is above the pressure chamber 3, and the fluid is sucked from the inlet 4 at the lower left portion of the drawing and discharged from the outlet 5 at the lower right portion of the drawing. This pump sucks the fluid from the inlet side and discharges it to the outlet side by increasing or decreasing the volume of the pressure chamber 3 by the displacement (vibration) of the diaphragm above the pressure chamber.

FIG. 2 (a) is a plan view of the second substrate 2 showing the movement of the fluid when the diaphragm is displaced upward, as viewed from above. If the diaphragm is displaced upwards,
Since the volume of the pressure chamber 3 increases and the pressure in the pressure chamber 3 decreases, the fluid is sucked in from both the inlet 4 and the outlet 5. The suction amount 13a sucked from the inlet 4 is equal to the first chamber 9
Is sucked into the pressure chamber 3 through the nozzle 11 having a low suction resistance. On the other hand, the suction amount 13b sucked from the outlet 5 is
The second chamber 10 is sucked into the pressure chamber 3 through a portion having the protrusion 12A having a large suction resistance in a direction opposite to the protrusion 12A. At this time, since the suction resistance from the inlet 4 direction to the pressure chamber 3 is small and the suction resistance from the outlet 5 direction to the pressure chamber 3 is large, the suction amount 13a from the inlet 4 becomes larger than the suction amount 13b from the outlet 5. . In other words, the first
The fluid in the entire width of the first chamber 9 is discharged from the chamber 9 of the nozzle 11
The fluid that has just flowed into the pressure chamber 3 from the second chamber 10 is guided to the pressure chamber 3 from the second chamber 10, but from the flow channel width sandwiched by the protrusions 12A. The outflow on the outside diverts to the side and the pressure chamber 3
It doesn't flow to.

FIG. 2B is a plan view of the second substrate 2 as seen from above, showing the movement of the fluid when the diaphragm is displaced downward. When the diaphragm is displaced downward, the volume of the pressure chamber decreases and the pressure in the pressure chamber 3 increases, so that the fluid is discharged to both the inlet 4 and the outlet 5. Discharge amount 1 discharged from the pressure chamber 3 to the second chamber 10
3d is discharged to the second chamber 10 through the nozzle 11A having a small suction resistance of the pressure chamber 3. On the other hand, the discharge amount 13c discharged from the pressure chamber 3 to the first chamber 9 passes through a portion of the pressure chamber 3 having the protrusion 12 having a large suction resistance in a direction reverse to the protrusion 12, and the first chamber 9 is discharged. Is discharged to. On this occasion,
Since the discharge resistance from the pressure chamber 3 to the outlet 5 is small and the discharge resistance from the pressure chamber 3 to the inlet 4 is large, the discharge amount 13d in the outlet 5 direction is larger than the discharge amount 13c in the inlet 4 direction. .

In the micropump of the present embodiment, the discharge amount ΔQ by one displacement of the diaphragm above and below the pressure chamber is given by the equation (1), and the flow rate is increased in proportion to the displacement number of the diaphragm up and down. It is possible to discharge the fluid from the inlet side to the outlet side.

ΔQ = 13a-13b = 13d-13c (1) The pump performance was investigated using the micropump shown in FIG. A piezoelectric element was used for the actuator that drives the diaphragm pump, and water, which is an incompressible fluid, was used as the fluid. The size of the diaphragm was 5 mm square. FIG. 3 shows the relationship between the discharge pressure and the driving frequency.
The discharge pressure increased in proportion to the increase of the driving frequency, and the discharge pressure of 0.008 MPa was obtained at the driving frequency of 2000 Hz. FIG. 4 shows the relationship between the discharge flow rate and the driving frequency. In the figure, t indicates the displacement amount of the diaphragm. From the figure, it is found that the discharge flow rate increases as the drive frequency increases. Further, the result is that the discharge flow rate increases as the displacement amount t increases. Also, when air is used as the fluid, the pressure and the flow rate increase as the driving frequency of the piezoelectric element increases. Since this method does not use a diffuser or nozzle as in the conventional method, the processing accuracy did not directly affect the performance even when the pump was downsized. Further, in this method, since there is no portion where the flow velocity sharply rises in the fluid resistance portion, cavitation did not occur even if the drive frequency of the pump was increased.

A micropump according to a second embodiment of the present invention will be described with reference to FIG. The present embodiment is different from the first embodiment in that the first substrate 1a is not thinned and a portion thereof is not used as a diaphragm, but the first substrate 1a having a uniform thickness is used as a diaphragm as it is. The other points are the same as those of the first embodiment, and detailed description thereof will be omitted. In this method, the diaphragm portion is driven or vibrated by the actuator 7 from the outside of the pump substrate (first substrate 1a). The pressure chamber 3 is formed with a flow path having a protrusion that causes the fluid resistance of the present invention as in the above embodiment, and the fluid flowing from the inlet 4 is discharged from the outlet 5 by driving the actuator 7. Silicon, glass, or a metal thin film may be used as the material of the first substrate 1a. The glass is particularly preferably a glass having a glass composition such as aluminosilicate glass containing sodium. As the metal thin film, for example, a rolled material such as nickel, tungsten, an alloy of various metals, a metal sputtered film, or a vapor deposited film can be used.
Since the metal sputtered film and the vapor-deposited film have low material strength, they may be used as a diaphragm of a micropump having a size of 1 mm or less that handles an extremely small fluid. Regarding the bonding of the first substrate 1a and the second substrate 2, the first substrate 1
When aluminosilicate glass is used for a and silicon is used for the second substrate, the two substrates are heated to 400 ° C.
It is advisable to perform anodic bonding in which a voltage of V is applied for bonding. When a glass or metal thin film other than aluminosilicate glass is used for the first substrate 1a and silicon is used for the second substrate 2, gold-silicon eutectic bonding, aluminum-silicon eutectic bonding, and a metal on the bonding surface are used. It is possible to apply diffusion bonding, in which diffusion is performed by sandwiching the substrate, or surface activation bonding, in which bonding is performed while activating the bonding surface in a vacuum using an ion beam or an atom beam. However, when the insert material 15 is sandwiched between the joint surfaces, the height amount of the pressure chamber 3, that is, the gap amount after assembling changes by the thickness of the insert material 15. Therefore, when the compressive fluid is used, the change amount of the gap amount. Should be taken into account when designing.

The micropump according to the third embodiment of the present invention will be described with reference to FIG. In this embodiment, the first substrate 1a is applied as a diaphragm as it is as in the above, but the difference between this embodiment and the second embodiment is that
Instead of the actuator 7 of the second embodiment, in this embodiment, both the first substrate 1a and the second substrate 2 are electrically controlled by the electronic circuit 16 to utilize electrostatic attraction. That is, the diaphragm portion is driven or vibrated in the vertical direction, and the insulating film 30 is interposed between the first substrate 1 a and the second substrate 2. The rest of the configuration is the same as that of the second embodiment, so a detailed description is omitted.
Since static electricity is used in this method, for example, an insulating film 30 such as glass is required between the first substrate and the second substrate. The material of the first substrate 1a may be a conductive material such as silicon or a metal thin film. In addition, silicon is preferably used for the second substrate. Furthermore, if silicon is applied to both substrates, there is an advantage that a control circuit can be built. In addition, a bimorph element or a bimetal element can be applied to the first substrate as an actuator.

In each of the above-described embodiments, as in the fourth embodiment shown in FIG. 7, by forming the silicon substrate in four layers, the micropump and the microchannel can be integrally formed. When a complicated flow path is required, it can be formed in multiple layers. In this embodiment, in addition to the pump of the first embodiment, a flow path substrate 17 which is a third substrate is bonded to the surface of the second substrate 2 on which the inlet 4 and the outlet 5 are formed, A flow path substrate 18, which is a fourth substrate, is bonded to the surface of the substrate 17 opposite to the second substrate 2. The flow path substrates 17 and 18 are larger than the second substrate 2, and there remains a substrate surface that is not bonded to the second substrate 2, and the flow path substrate 17 has an inlet 4 of the second substrate 2, An opening (inlet 4A, outlet 5A) penetrating in the plate thickness direction at a position facing the outlet 5
Is formed, and two openings (an inlet 4B and an outlet 5B) penetrating in the plate thickness direction are formed on the substrate surface not bonded to the second substrate 2. Micro flow channels 19 and 19A are formed on the surface of the flow channel substrate 18 that is the fourth substrate to be bonded to the flow channel substrate 17, and the micro flow channel 19 is the flow channel substrate of the flow channel substrate 18. 17 entrance 4A
And the microchannel 19A are arranged so as to connect the positions facing the inlet 5B and the outlet 5A of the channel substrate 17 of the channel substrate 18, respectively.

By driving the actuator, the flow path substrate 1
The fluid that has flowed in from the inlet 4B located at a position apart from the joint portion of 7 to the second substrate is discharged to the outlet 5B through the micropump and the microchannels 19 and 19B. By forming such a structure, as shown in FIG. 8, a pump system in which the fluid tank 20 is mounted at a position apart from the joint of the flow path substrate 17 to the second substrate can be obtained. In this method, since the portion using the hose is small, the usage amount can be reduced when the reagent for analysis is used as the fluid, for example. Further, it can be used as a reagent supply pump for analysis or a cooling pump for cooling only a minute range. The above-mentioned multilayer silicon substrate has sufficient strength, but since silicon is a brittle material, it is weak against impact. Therefore, the thickness is 0.5m on both sides of the multilayer silicon substrate.
As a result of anodic bonding of m glass (not shown), the impact force increased.

FIG. 9 shows an example of a system diagram (flow chart) of the chemical analysis system of the fifth embodiment using the micropump of the present invention. This system includes a micro pump 25A connected to the container 41 via a filter 24A.
A micro pump 25B connected to the container 42 via the filter 24B, a micro pump 25C connected to the container 43 via the filter 24C, and a micro pump 25D connected to the container 44 via the filter 24D.
A mixer 26B for mixing the discharge fluid of the micro pump 25C and the discharge fluid of the micro pump 25D, the discharge pipe 31 of the micro pump 25B and the outlet pipe 32 of the mixer 26B.
A mixer 26A that is connected to the mixer and mixes fluids sent from both of them, a discharge pipe 33 that connects the discharge pipe 31 and the discharge port of the micropump 25A, and a laser analysis system 27 that is connected to the outlet side of the mixer 26A. , A waste liquid tank 28 connected to the output side of the laser analysis system 27. As the micropumps 25A to 25D, the ones described in the first embodiment are used. The cleaning liquid 21 is stored in the container 41, the sample 22 is stored in the container 42, and the reagents 23A and 23B are stored in the containers 43 and 44, respectively. Since the reagents 23A and 23B are usually mixed and used, the outlet pipe 32 does not need to be washed.

An appropriate amount of the sample 22 to be analyzed is sucked up from the container 42 by the micropump 25B. On the other hand, the reagent 23 for analysis is sucked up from the container 43 through the filter 24C by the micropump 25C, is mixed with the sample 22 by the mixer 26A, is subjected to component analysis in the laser analysis system 27, and is then collected in the waste liquid tank 28. To be Further, once the analysis is completed, the discharge pipe 31 and the mixer 26
The inside of the flow path connecting A and the laser analysis system 27 is cleaned with the cleaning liquid 21. By using the micropump of the present invention and integrating or systematizing the pump and a detection system equipped with a flow path and a laser analysis system, the chemical analysis device, which was a large system in the past, can be downsized to a portable size. It becomes possible.

Next, another embodiment relating to the pressure chamber and the flow path formed on the second substrate 2 will be described with reference to FIGS.
Will be explained. In principle, in the micropump of the present invention, the fluid sucked from the inlet may be sucked into the pressure chamber without receiving fluid resistance. Therefore, as in the sixth embodiment shown in FIG. 10, the first chamber can be used as a micropump even if it is changed to the shape of the flow path 29 instead of being an independent section.

According to the present invention, it is not always necessary to form a protrusion in the pressure chamber. As in the case of the seventh embodiment shown in FIG. 11, the projections 1 are formed in the flow passages extended on both sides of the pressure chamber 3.
A pump action can be generated even when 2, 12A is formed. As a result of the experiment, the pump action could be confirmed. With such a structure, a very small 2
It was possible to form a mm-square micropump.

FIG. 12 relates to the shape of the projection formed in the pressure chamber, the flow path or the second chamber according to the present invention.
The figure shows the shape of the protrusion formed in the pressure chamber 3.
2A shows a shape in which the tip of the projection is sharp, FIG. 12B shows a shape in which the tip of the projection is angular, and FIG. 12C shows a shape in which the tip of the projection is round. As a result of the experiment, it was confirmed that any tip shape functions as a fluid resistance and the pumping action. It should be noted that the protrusion structure which is symmetrical with respect to the center line of the flow path or the pressure chamber, extends in the direction in which the fluid flows, and is arranged parallel to the direction in which the fluid flows has the best efficiency.

An eighth embodiment of the pressure chamber and the flow path formed on the second substrate of the present invention will be described with reference to FIG. In FIG. 13, three pump structures formed on the second substrate 2 are arranged in parallel. 3 as shown
In this pump, the inlet 4 and the outlet 5 are the same, and the portion shown by the dotted line shows the portion where the volume changes due to the diaphragm. By using such a structure, it can be used as a micropump for obtaining a large flow rate. Also,
By arranging a plurality of pump structures of the present invention with the same inlet and outlet, it is possible to freely control the flow rate range. Furthermore, by disposing a plurality of pump structures of the present invention with separate inlets and outlets, it is possible to handle other types of fluids as a single pump unit, which is suitable as a micropump for a chemical analyzer or the like.

Furthermore, by integrating or systematizing the above-mentioned pump unit and the detection system equipped with the flow path and the laser optical system, the chemical analysis device, which was a large system in the past, can be downsized to a portable size. It is possible to apply to environmental measurement, medical care such as home nursing, quality control, etc. On the other hand, by miniaturizing the pump, it is possible to reduce the amount of reagents and waste liquid to be used for analysis, and it is possible to provide a maintenance-free and environmentally friendly portable type small chemical analysis device because the device is small. It is preferable that the micropump used for such a chemical analysis is made of a material having a high chemical resistance including the joint portion. When a material having low chemical resistance is applied, it is preferable to use a chemical resistant material, for example, a thin film of polytetrafluoroethylene, on the surface of the flow path through which the fluid flows.

A ninth embodiment relating to the pressure chambers and flow passages formed on the second substrate of the present invention will be described with reference to FIG. In FIG. 14, three pressure chambers 3 are arranged in series on the second substrate 2 between the inlet 4 and the outlet 5. The part indicated by the dotted line shows the part where the volume changes due to the diaphragm. High pressure could be obtained by using such a structure and controlling the drive of the diaphragm by an electric circuit. Moreover, it was possible to freely control the pressure range by disposing a plurality of pressure chambers. Besides, a thin scribe line having a width of 5 μm and a depth of 5 μm was formed in the flow direction on the bottom surface of the pressure chamber, and as a result, the pressure could be increased. Further, the flow passages as shown in FIG. 11 are provided on both sides of the pressure chamber in three stages by gradually changing the flow passage width, and each of the flow passages has one protrusion of the present invention, the inlet side, and the outlet side. With the method of providing three places each, the pump pressure could be increased. Further, in each of the above embodiments, one pressure chamber is provided with a pair of protrusions at the inlet and the outlet, but a plurality of nozzles serving as the inlet and the outlet are provided at the pressure chamber, and the protrusion of the present invention is provided for each nozzle. Higher pressure was obtained by providing the parts.

In the present invention, the pump structure formed on the second substrate is not limited to the linear shape but may be a curved shape as in the tenth embodiment shown in FIG. In this pump structure, since there is no part like a corner, stagnation etc. does not occur due to the fluid flowing in the pressure chamber,
Since the fluid resistance decreases, the fluid can flow smoothly. The above-mentioned pump structure was formed by etching a silicon portion to a depth of about 5 μm using a reactive ion etching device. Processing conditions are gas, sulfur hexafluoride (SF6)
And RF power input using trifluoromethane (CHF3)
A photoresist was used as a mask material at 0 W and a vacuum degree of 40 Pa. Besides the resist, the mask may be formed of a metal thin film of aluminum, platinum, nickel or the like by sputtering or vapor deposition.

In each of the above-mentioned embodiments, the pump and the outside for supplying the fluid may be connected by a hose, for example. However, when silicon is used as the pump material, a hose is inserted at the inlet or the outlet. It is preferable to use a method of forming a hole for the hose, or a method of forming a protrusion for inserting the hose by anisotropic etching.

As the material of the second substrate in each of the above-mentioned embodiments, the method of forming it by using silicon is the best in terms of accuracy and mass productivity, but in the present invention, in addition to this, a metal material or plastic is used for the second substrate. The material can be used to form a micropump. For example, when a metal material such as stainless steel is used, the pressure chamber, the flow path, or the like may be subjected to transfer processing using a die such as press working or coining. When using a plastic material, injection molding is preferably used.

[0045]

According to the micropump of the present invention, strict machining accuracy is not required, so that the micropump is excellent in mass productivity and is excellent in compatibility with a complicated minute flow path. Therefore, a low-cost micro pump can be supplied. Also,
It is possible to provide a high-performance micro pump with a wide range of pressure and flow rate.

[Brief description of drawings]

FIG. 1 is a sectional view and a plan view showing a first embodiment of the present invention.

FIG. 2 is a plan view showing a fluid flow in the embodiment of FIG.

FIG. 3 is a graph showing the relationship between discharge pressure and drive frequency according to the embodiment of the present invention.

FIG. 4 is a graph showing the relationship between the discharge flow rate and the drive frequency according to the embodiment of the present invention.

FIG. 5 is a cross-sectional view showing a second embodiment of the present invention.

FIG. 6 is a sectional view showing a third embodiment of the present invention.

FIG. 7 is a perspective view showing a partial cross section showing a fourth embodiment of the present invention.

FIG. 8 is a perspective view showing the appearance of the embodiment shown in FIG.

FIG. 9 is a system diagram showing a fifth embodiment of the present invention.

FIG. 10 is a plan view showing a sixth embodiment of the present invention.

FIG. 11 is a plan view showing a seventh embodiment of the present invention.

FIG. 12 is a plan view showing an example of the shape of a protrusion according to the present invention.

FIG. 13 is a plan view showing an eighth embodiment of the present invention.

FIG. 14 is a plan view showing a ninth embodiment of the present invention.

FIG. 15 is a plan view showing a tenth embodiment of the present invention.

[Explanation of symbols]

1, 1a 1st substrate 2 2nd substrate 3 Pressure chamber 4, 4A, 4B
Inlet 5, 5A, 5B Outlet 7 Actuator 8 Diaphragm 9 First chamber 10 Second chamber 11, 11A Nozzle 12, 12A Protrusions 13a to 13d
Intake amount or discharge amount 14 Deformation part of diaphragm 15 Insert material 16 Electric circuit 17, 18 Flow path substrate 19 Micro flow path 20 Fluid tank 21 Cleaning liquid 22 Samples 23A, 23B Analytical reagents 24A to 24D
Filters 25A to 25D Micro pumps 26A and 26B
Mixer 27 Laser analysis system 28 Waste liquid tank 29 Flow path 30 Insulating film 31 Discharge pipe 32 Outlet pipe 33 Discharge pipe 41-44 Container

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Ryo Miyake 502 Jinritsucho, Tsuchiura City, Ibaraki Prefecture Machinery Research Laboratory, Hitachi, Ltd. (56) References JP 61-180075 (JP, A) JP 62- 221884 (JP, A) JP-A-5-340356 (JP, A) JP-A-7-167846 (JP, A) JP-A-60-228300 (JP, A) JP-A-8-506874 (JP, A) (58) Fields surveyed (Int.Cl. ⁷ , DB name) F04B 43/02

Claims (6)

(57) [Claims] 1. A pressure chamber <br/> Daiafura beam which vibrates in the thickness direction is made form with at least a portion of the wall surface at least a portion of the pressure chamber with leading to the inlet of the fluid inlet
The flow path or chamber connected to the mouth side and the outlet side of the pressure chamber
It and a chamber connected to the outlet of the fluid with lead, before Kida diaphragm and alter the volume of the pressure chamber by vibrating the fluid resistance when handling fluid flows into the pressure chamber by the volume change wherein a valveless micro pump for discharging the fluid by utilizing the difference in fluid resistance when flowing out of the pressure chamber, the inlet side of the pressure chamber, and connected to the outlet side of the pressure chamber
The inlet side of that chamber, respectively, in said die A Fram plane parallel to the surface, the center line of the pressure chamber towards the interior of the pressure chamber
It has a symmetrical shape and extends parallel to the direction of fluid flow.
Of a pair of protrusions formed in a circular shape and the outlet of the pressure chamber
Toward the inside of the chamber connected to the side
It has a symmetrical shape and extends parallel to the direction of fluid flow.
Micropump being characterized in that a pair of collision force formed in the shape of. 2. A first group on which the diaphragm is formed.
A plate and a first substrate that is arranged facing and in contact with the first substrate.
And a second substrate, the second substrate containing the pressure chamber
A flow path or chamber connected to the mouth side, the pressure chamber, and the pressure
The depression that becomes the chamber connected to the outlet side of the force chamber, and the pressure
A pair of protrusions formed toward the inside of the chamber and the pressure
One formed toward the inside of the chamber that connects to the outlet side of the chamber
The micropump according to claim 1, wherein a pair of protrusions are formed . 3. The micropump according to claim 1, wherein a plurality of the pressure chambers are arranged in series. 4. The micropump according to claim 2 , wherein silicon is used as a material of the first substrate and the second substrate. 5. A third substrate is arranged in contact with the surface of the second substrate opposite to the surface in contact with the first substrate, and the side of the third substrate opposite to the second substrate. a fourth substrate disposed in contact with the surface, according to claim 2 in which between the third substrate and the fourth substrate, wherein the micro flow path leading to the inlet and the outlet are formed 5. The micropump according to any one of 4 to 4. 6. A plurality of storage tanks for respectively storing different liquids, a plurality of micropumps whose suction sides are connected to the respective storage tanks through filters, and a discharge side of the plurality of micropumps which are connected via a mixer. Analysis means,
A micropump system including the micropump, wherein the micropump is the micropump according to any one of claims 1 to 5.