JP2005030213A - Piezoelectric micro pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To piezoelectric micro pump, that can be driven at low voltage, and that is capable of stabilizing flow quantity. <P>SOLUTION: This piezoelectric micro pump is composed of a lower electrode layer 28, a piezoelectric thick film 29, and an upper electrode layer 30 laminated on the side of a first main surface 23 of an Si substrate 22. On the Si substrate 22, a diaphragm part 31 is formed on the side of the first main surface 23, an opening 33 is formed on the side of a second main surface 32, and a pump chamber 34, a discharge side flow passage 35, and a supply side flow passage 36 are provided. The opening 33 is sealed with a sealing layer 40. A discharge side flow passage 35 and a supply side flow passage 36 are composed of a discharge side taper valve 37 and a supply side taper valve 38. A restrictor part 39 as a pressure increasing part is provided on the discharge side taper valve 37. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a piezoelectric micropump, and more particularly to an improvement in a piezoelectric micropump that enables low-voltage driving and stabilizes the flow rate.
[0002]
[Prior art]
As piezoelectric micropumps of interest to the present invention, there are those described in Patent Documents 1 and 2. Conventional piezoelectric micropumps including those described in Patent Documents 1 and 2 generally include the following: It has such a configuration.
[0003]
FIG. 7 is a front view showing the conventional piezoelectric micropump 1 in cross section, and FIG. 8 is a cross section taken along line CC in FIG.
[0004]
The piezoelectric micropump 1 includes a Si substrate 2, and a diaphragm portion 4 is formed on the first main surface 3 side of the Si substrate 2, and the second main surface 5 side facing the first main surface 3. A pump chamber 7 is provided in a state in which an opening 6 is formed in the front. In addition, the Si substrate 2 is provided with a discharge-side channel 8 and a supply-side channel 9 communicating with the pump chamber 7 at positions facing each other. The discharge side flow path 8 and the supply side flow path 9 are provided by a discharge side taper valve 10 and a supply side taper valve 11, respectively.
[0005]
A sealing layer 12 made of, for example, heat-resistant glass is bonded to the second main surface 5 of the Si substrate 2, thereby sealing the opening 6 described above.
[0006]
On the other hand, a piezoelectric plate 15 formed so that the electrodes 13 and 14 are opposed to each other on each main surface thereof is prepared, and this piezoelectric plate 15 is connected to the first of the Si substrate 2 via the adhesive layer 16. The main surface 3 is joined.
[0007]
9A and 9B are diagrams for explaining the operation of the piezoelectric micropump 1. FIG. 9A shows the discharge-side taper valve 10 and FIG. 9B shows the supply-side taper valve 11. In FIG. 9, an arrow 17 indicates the pressurizing direction when the pump chamber 7 is in the compression stroke.
[0008]
Each of the taper valves 10 and 11 has a fluid resistance that varies depending on the direction of the fluid flowing therethrough. That is, when the fluid flows according to the pressurizing direction 17, the discharge side taper valve 10 shown in FIG. 9A has a large fluid resistance and the fluid does not flow easily. On the other hand, in the supply side taper valve 11 shown in FIG. 9B, when the fluid flows according to the pressurizing direction 17, the fluid resistance is small and the fluid easily flows. As a result, when the pump chamber 7 is in the compression stroke, the flow rate at the discharge-side taper valve 10 becomes larger than the flow rate at the supply-side taper valve 11, so that the fluid is supplied to the supply-side taper valve while the backflow is suppressed. The pump motion that flows from 11 toward the discharge-side taper valve 10 becomes possible.
[0009]
Such a piezoelectric micropump 1 is applied to, for example, a fuel cell for portable devices, a microanalyzer, and the like.
[0010]
[Patent Document 1]
JP 2002-311213 A [Patent Document 2]
Japanese Patent Laid-Open No. 2002-328212
[Problems to be solved by the invention]
However, the piezoelectric micropump 1 shown in FIGS. 7 and 8 has the following problems.
[0012]
First, since the mechanical strength of the piezoelectric plate 15 is relatively low, there is a limit to making it thin. Therefore, it is difficult to obtain a large driving force in the piezoelectric plate 15 with a low voltage of, for example, about several volts. Therefore, it is difficult to generate a pump motion that can greatly deform the pump chamber 7.
[0013]
Moreover, although the flow rate in the discharge side flow path 8 can be increased by the discharge side taper valve 10 and the supply side taper valve 11 that are paired with each other, a decrease in the discharge pressure of the fluid on the discharge side is inevitable. For example, when it is directed to an application such as a microreactor, a pump structure capable of maintaining a high discharge pressure is required in order to be able to pressure-feed gas generated in the reactor to the outside of the reactor. Therefore, in order to enable application to, for example, a microreactor, it is desired to realize a pump structure that can maintain a higher discharge pressure.
[0014]
Therefore, an object of the present invention is to provide a piezoelectric micropump that can solve the above-described problems.
[0015]
[Means for Solving the Problems]
In order to solve the above technical problem, the piezoelectric micropump according to the present invention is characterized by having the following configuration.
[0016]
The piezoelectric micropump according to the present invention includes a substrate. On the first main surface side of the substrate, a lower electrode layer, a piezoelectric thick film, and an upper electrode layer are laminated in this order.
[0017]
The substrate is provided with a pump chamber in a state where a diaphragm portion is formed on the first main surface side and an opening is formed on the second main surface side facing the first main surface. A discharge-side flow path and a supply-side flow path that communicate with each other are provided.
[0018]
The above-described opening is sealed with a sealing layer. The sealing layer is preferably made of heat resistant glass.
[0019]
In addition, at least a part of each of the discharge-side flow channel and the supply-side flow channel is provided by a discharge-side taper valve and a supply-side taper valve, respectively, and the discharge-side taper valve is provided with a throttle portion that serves as a boosting portion. .
[0020]
In the present invention, the substrate is preferably provided by a Si substrate. In this case, it is preferable that a buffer layer for suppressing mutual diffusion is further formed between the Si substrate and the lower electrode layer.
[0021]
The piezoelectric micro pump according to the present invention may include a plurality of pump chambers arranged in parallel. In this case, at least the piezoelectric thick film and the upper electrode layer are provided in association with each of the plurality of pump chambers, and the discharge side channel and the supply side channel respectively connect the plurality of pump chambers to each other. A discharge side communication path and a supply side communication path are provided, and the discharge side taper valve and the supply side taper valve are provided to communicate with the discharge side communication path and the supply side communication path, respectively.
[0022]
When the above-described configuration is adopted, a part of the plurality of pump chambers is driven in the steady state, and when a failure occurs in the pump chamber driven in the steady state, at least the remaining pump chambers. It is preferred that part is driven.
[0023]
The piezoelectric micro pump according to the present invention may include a plurality of pump chambers arranged in series. In this case, at least the piezoelectric thick film and the upper electrode layer are provided in association with each of the plurality of pump chambers, and at least a part of two adjacent pump chambers is provided by a taper valve. Connected to each other by a flow path, the discharge side flow path is provided in communication with the pump chamber located on the most downstream side in the fluid flow direction, and the supply side is connected to the pump chamber located on the most upstream side. The flow path is provided so as to communicate.
[0024]
When the above-described configuration is adopted, the plurality of pump chambers are preferably driven with phases different from each other so as to perform a peristaltic movement.
[0025]
Both of the above-described parallel arrangement of the plurality of pump chambers and series arrangement of the plurality of pump chambers may be employed. That is, while a plurality of pump chambers are arranged in series, those arranged in series may be arranged in parallel.
[0026]
DETAILED DESCRIPTION OF THE INVENTION
1 to 3 illustrate a piezoelectric micropump 21 according to a first embodiment of the present invention. Here, FIG. 1 is a front view showing the piezoelectric micropump 21 in section, FIG. 2 is a sectional view taken along line AA in FIG. 1, and FIG. 3 is taken along line BB in FIG. It is sectional drawing which follows.
[0027]
The piezoelectric micropump 21 includes a Si substrate 22 as a substrate. On the first main surface 23 side of the Si substrate 22, a SiO ₂ layer formed by thermally oxidizing the Si substrate 22 and a first buffer layer 25 made of NiO or MgO formed on the SiO ₂ layer 24. A second buffer layer 26 made of Al ₂ O ₃ formed on the first buffer layer 25, a Pd oxide layer 27 containing Pd formed on the second buffer layer 26, and a Pd oxide A lower electrode layer 28 made of Pt or a Pt—Ni alloy formed on the material layer 27, a piezoelectric thick film 29 formed on the lower electrode layer 28, and Pt formed on the piezoelectric thick film 29. The upper electrode layer 30 is laminated.
[0028]
The piezoelectric thick film 29 is formed by a thick film forming technique in which a piezoelectric paste is applied and fired, and preferably, Japanese Patent Application No. 2001-207385 (Japanese Patent Laid-Open No. 2003-20274) filed by the present applicant. And the piezoelectric paste disclosed in Japanese Patent Laid-Open Publication No. 1993). This piezoelectric paste is a Pb (Zr, Ti) O ₃ —Pb (Zn, Nb) O ₃ based piezoelectric crystal powder and a ferroelectric phase that precipitates in the course of heat treatment and becomes a liquid phase at high temperature. It includes crystallized glass powder in an amorphous state having an ability to obtain, and an organic vehicle.
[0029]
Piezoelectric crystal powder described above, 90 to 70 mol% of _{Pb (Zr x Ti 1-x} ) O 3 ( here, x is from 0.49 to 0.56) and 10 to 30 mol% of Pb (Zn _{1 / 3} Nb _2/3 ) O ₃ is preferable. In addition, the crystallized glass powder preferably has a PbO—GeO ₂ -based composition in which a Pb ₅ Ge ₃ O ₁₁ ferroelectric phase is precipitated by increasing the temperature. For example, yPbO— (100-y) GeO ₂ (however, , Y is more preferably 50 to 80 mol%).
[0030]
According to the stacked structure as shown in FIGS. 1 and 2, the first buffer layer 25 made of NiO or MgO is located between each of the SiO ₂ layer 24 and the second buffer layer 26 made of Al ₂ O _3. Can provide stable bondability. The second buffer layer 26 has good adhesion to the Pd oxide layer 27, and the Pd oxide layer 27 has good adhesion to the lower electrode layer 28.
[0031]
The first buffer layer 25 made of NiO or MgO and the second buffer layer 26 made of Al ₂ O ₃ are both directly connected to Pb contained in the piezoelectric thick film 29 formed of the piezoelectric paste described above. It is difficult to react. Further, the first buffer layer 25 made of NiO or MgO has low reactivity with respect to both the SiO ₂ layer 24 and the second buffer layer 26 made of Al ₂ O ₃ .
[0032]
Therefore, the heat treatment for forming the piezoelectric thick film 29 does not impair the above-described good bondability, and the reactivity of each of the first buffer layer 25 and the second buffer layer 26 described above. Therefore, the properties of the piezoelectric thick film 29 are not impaired.
[0033]
The Si substrate 22 is provided with a pump chamber 34 in a state where a diaphragm portion 31 is formed on the first main surface 23 side and an opening 33 is formed on the second main surface 32 side facing the first main surface. It has been. In addition, the Si substrate 22 is provided with a discharge-side channel 35 and a supply-side channel 36 that communicate with the pump chamber 34 at positions facing each other. Further, the discharge side channel 35 and the supply side channel 36 constitute a discharge side taper valve 37 and a supply side taper valve 38, respectively.
[0034]
In addition, the above-described discharge side taper valve 37 is provided with a throttle portion 39 serving as a pressure increasing portion that provides fluid resistance.
[0035]
Further, the sealing layer 40 is bonded to the second main surface 32 of the Si substrate 22, whereby the opening 33 of the pump chamber 34 is sealed. The sealing layer 40 is preferably made of heat-resistant glass such as a plate shape. As this heat-resistant glass, it is preferable to use a glass having a thermal expansion coefficient closer to that of the Si substrate 22.
[0036]
According to the piezoelectric micropump 21 having the above-described configuration, the diaphragm portion 31 in the Si substrate 22 can be reduced in thickness, and the piezoelectric thick film 29 can be replaced with the piezoelectric plate 15 in the conventional example shown in FIG. Compared to, it can be made thinner. Therefore, the volume displacement of the diaphragm part 31 can be increased even by low voltage driving, and a large driving force can be obtained. Further, since the adhesive layer 16 used in the conventional example shown in FIG. 7 is not required, damping caused by this can be avoided.
[0037]
In addition, since the discharge side taper valve 37 is provided with the throttle portion 39, the rectification function by this is exhibited, the backflow can be reduced, the flow rate can be stabilized, and the flow rate can be easily controlled. In addition, a high discharge pressure can be ensured.
[0038]
The piezoelectric micropump 21 is manufactured as follows as an example.
[0039]
First, on the first main surface 23, a (001) -oriented Si substrate 22 including a SiO ₂ layer 24 formed as a thermal oxide film having a thickness of 1 μm is prepared. Next, anisotropic etching is applied to the second main surface 32 of the Si substrate 22 to form a pump chamber 34 having a plane dimension of 6 mm × 6 mm, and the discharge side taper valve 37 and the supply side taper valve. The discharge-side flow path 35 and the supply-side flow path 36 that respectively constitute 38 are formed. At this time, the thickness of the diaphragm portion 31 in the Si substrate 22 is controlled to 30 μm.
[0040]
Next, a first buffer layer 25 made of MgO and having a thickness of 600 nm is formed on the SiO ₂ layer 24 by reactive sputtering, and then a second buffer layer 26 made of Al ₂ O ₃ and having a thickness of 150 nm. Form.
[0041]
Next, a Pd oxide layer 27 made of PdO _x and having a thickness of 50 nm is formed on the second buffer layer 26, and further, a lower electrode layer 28 made of Pt and having a thickness of 500 nm is formed by high-frequency sputtering.
[0042]
Next, after spraying a fluorine release agent on the pump chamber 34, a room temperature curing type silicone rubber is molded and thermally cured, thereby temporarily reinforcing the diaphragm portion 31.
[0043]
Next, a Pb (Zr, Ti) O ₃ —Pb (Zn _1/3 Nb _2/3 ) O ₃ piezoelectric paste is applied on the lower electrode layer 28 by screen printing, dried, and then coated. Is pressurized.
[0044]
Next, after the above-mentioned silicone rubber is peeled off, the piezoelectric thick film 29 having a thickness of about 15 μm and a plane dimension of 4 mm × 4 mm is formed in the diaphragm portion 31 by firing in air at a temperature of 850 ° C. Formed above.
[0045]
Next, the upper electrode layer 30 made of Pt is formed on the piezoelectric thick film 29 so as to have a thickness of 200 nm.
[0046]
Next, the second main surface 32 in which the opening 33 of the pump chamber 34 in the Si substrate 22 is formed is treated with hydrofluoric acid to remove SiO ₂ on the surface, and then the sealing layer 40 made of heat resistant glass is formed on the Si layer 22. The second main surface 32 of the substrate 22 is brought into contact, and in that state, a voltage of 750 V is applied while heating to a temperature of 400 ° C., and the sealing layer 40 and the Si substrate 22 are bonded by anodic bonding.
[0047]
Next, the piezoelectric thick film 29 is polarized by applying an electric field of 50 kV / cm to the piezoelectric thick film 29 at a temperature of 80 ° C. for 30 minutes.
[0048]
The piezoelectric micro pump 21 can be obtained as described above.
[0049]
Next, the result of an experiment conducted to actually manufacture the piezoelectric micropump 21 by the specific manufacturing method as described above and confirm its performance will be described. In this experiment, the following evaluation results were obtained.
[0050]
When the piezoelectric micropump 21 was driven under the conditions of applied voltage (sine wave pulse) 5V _pp and drive frequency 1 kHz, a displacement of about 0.8 μm was confirmed at the center of the diaphragm 31 at a low voltage of 5V. The movement of the fluid filled in the pump chamber 34 was confirmed. At this time, the pump pressure corresponding to the discharge pressure was about 2 kPa. In the discharge side taper valve 37, when the pump pressure was measured for a piezoelectric micropump as a comparative example in which the throttle part 39 was not provided, it was about 0.7 kPa, which is an improvement in pump pressure compared to this comparative example. It could be confirmed.
[0051]
Further, according to the piezoelectric micropump 21, since the piezoelectric thick film 29 is used, there is almost no phase shift between the applied voltage waveform and the displacement waveform due to damping, and the quick response is good. Further, the presence of the throttle 39 in the discharge-side taper valve 37 also has the effect of improving rectification (pumping back flow) during the pump motion.
[0052]
FIG. 4 is a view corresponding to FIG. 3 for explaining the second embodiment of the present invention. 4, elements corresponding to those shown in FIG. 3 are denoted by the same reference numerals, and redundant description is omitted.
[0053]
The piezoelectric micro pump 21a shown in FIG. 4 includes a plurality of, for example, two pump chambers 41 and 42 arranged in parallel. Although not shown, at least the piezoelectric thick film 29 and the upper electrode layer 30 are provided in association with the pump chambers 41 and 42, respectively.
[0054]
The discharge-side flow path 35 and the supply-side flow path 36 are each provided with a discharge-side connection path 43 and a supply-side connection path 44 that connect the two pump chambers 41 and 42 to each other. The discharge side taper valve 37 is provided so as to communicate with the discharge side connection path 43, while the supply side taper valve 38 is provided so as to communicate with the supply side connection path 44.
[0055]
Such a piezoelectric micropump 21a may drive the two pump chambers 41 and 42 at the same time. Preferably, however, one of the pump chambers 41 is driven in a steady state, and the pump chamber 41 is malfunctioning. When this occurs, the other pump chamber 42 is used to be driven. As a result, even if a failure occurs in one of the pump chambers 41, the piezoelectric micropump 21a can be operated continuously, so that the piezoelectric micropump 21a can have a redundant function.
[0056]
As a modification of the second embodiment described above, an embodiment in which three or more pump chambers are arranged in parallel is also possible.
[0057]
FIG. 5 is a view corresponding to FIG. 3 for explaining a third embodiment of the present invention. In FIG. 5, elements corresponding to the elements shown in FIG. 3 are denoted by the same reference numerals, and redundant description is omitted.
[0058]
The piezoelectric micro pump 21b shown in FIG. 5 includes a plurality of, for example, two pump chambers 51 and 52 arranged in series. Although not shown, at least the piezoelectric thick film 29 and the upper electrode layer 30 are provided in association with each of the two pump chambers 51 and 52.
[0059]
Two adjacent pump chambers 51 and 52 are connected to each other by a flow path 54 provided at least in part by a taper valve 53. With respect to the flow direction of the fluid, the pump chamber 51 located on the most downstream side, that is, the pump chamber 51 is provided so as to communicate with the discharge-side flow path 35 constituting the discharge-side taper valve 37, and on the other hand, on the most upstream side. The supply side flow path 36 constituting the supply side taper valve 38 is provided so as to communicate with the pump chamber, that is, the pump chamber 52.
[0060]
The piezoelectric micropump 21b described above may drive the two pump chambers 51 and 52 simultaneously with the same phase, but preferably the two pump chambers 51 and 52 are driven with different phases. More specifically, one pump chamber 51 is driven with a phase that is shifted by a half period with respect to the other pump chamber 52, thereby causing a dynamic motion.
[0061]
According to the drive method as described above, when the first pump chamber 51 is in a state of sucking fluid, the movement of feeding the fluid from the second pump chamber 52 to the first pump chamber 51 is also performed at the same time. Therefore, the flow rate can be prevented from becoming unstable due to the pulsation caused by the insufficient supply of fluid into the first pump chamber 51, and a stable flow rate can be ensured.
[0062]
FIG. 6 is a view corresponding to FIG. 3 for explaining a fourth embodiment of the present invention. In FIG. 6, elements corresponding to the elements shown in FIG. 3 are denoted by the same reference numerals, and redundant description is omitted.
[0063]
The piezoelectric micro pump 21c shown in FIG. 6 is positioned as a combination of the characteristic configuration of the piezoelectric micro pump 21a shown in FIG. 4 and the characteristic configuration of the piezoelectric micro pump 21b shown in FIG.
[0064]
The piezoelectric micropump 21c shown in FIG. 6 includes a plurality of, for example, two pump chambers 61 and 62 connected in series with a first set, and a plurality of, for example, two sets connected in series with a second set. Pump chambers 63 and 64 are provided. Further, a set of pump chambers connected in series may be provided. Although not shown, at least the piezoelectric thick film 29 and the upper electrode layer 30 are provided in association with each of the plurality of pump chambers 61 to 64.
[0065]
The first pair of two adjacent pump chambers 61 and 62 are connected to each other by a flow channel 66 provided at least in part by a taper valve 65. On the other hand, two adjacent pump chambers 63 and 64 of the second set are connected to each other by a flow path 68 provided at least in part by a taper valve 67.
[0066]
The first set of pump chambers 61 and 62 arranged in series and the second set of pump chambers 63 and 64 arranged in series are arranged in parallel. The discharge-side flow path 35 includes a discharge-side connection path 69 that connects the pump chambers 61 and 63 located on the most downstream side with respect to the fluid flow direction, and the discharge-side taper valve 37 is connected to the discharge-side connection. It is provided so as to communicate with the path 69. On the other hand, the supply-side flow path 36 includes a supply-side connection path 70 that connects the pump chambers 62 and 64 positioned on the most upstream side with respect to the flow direction of the fluid. It is provided so as to communicate with the path 70.
[0067]
Also in the piezoelectric micro pump 21 c having such a configuration, for example, when the pump chambers 61 and 63 are driven and a failure occurs with respect to the pump chamber 61 in a steady state, the pump chamber 62 is driven. It is preferably used so that the pump chamber 64 is driven when a failure occurs. Further, the pump chambers 61 and 62 are driven with different phases so as to make a peristaltic movement. Similarly, the pump chambers 63 and 64 are driven with different phases so as to make a peristaltic movement. It is preferable.
[0068]
Therefore, according to the piezoelectric micropump 21c shown in FIG. 6, it is possible to obtain both the effect obtained by the piezoelectric micropump 21a shown in FIG. 4 and the effect obtained by the piezoelectric micropump 21b shown in FIG. it can.
[0069]
While the present invention has been described with reference to the illustrated embodiment, various other modifications are possible within the scope of the present invention.
[0070]
For example, the laminated structure employed in the piezoelectric micropump and the material of each layer can be changed as necessary. As a modification, a Si substrate, a SiO ₂ layer formed on the Si substrate, a buffer layer made of Al ₂ O ₃ formed on the SiO ₂ layer, and Pb—Ru— formed on the buffer layer. Bi-O conductive composite oxide layer, electrode layer containing Pt formed on the conductive composite oxide layer, Pb-based piezoelectric thick film formed on the electrode layer, and Pb-based piezoelectric body A laminated structure including an upper electrode layer formed on a thick film can also be adopted.
[0071]
【The invention's effect】
As described above, according to the piezoelectric micropump according to the present invention, not only can the diaphragm portion formed on the substrate be thinned, but also a piezoelectric thick film is formed as a piezoelectric body. Can also be achieved. Therefore, a large volume displacement can be obtained in the diaphragm portion even by low voltage driving, and the driving force can be increased. In addition, since a piezoelectric plate is not used as the piezoelectric body, it is not necessary to use an adhesive for bonding it to the substrate, and therefore damping by the adhesive can be avoided.
[0072]
In addition, the discharge side taper valve that constitutes at least a part of the discharge side flow path communicating with the pump chamber is provided with a throttle portion that serves as a boosting portion. The flow rate can be stabilized. In addition, the flow rate can be easily controlled, and a high discharge pressure can be secured.
[0073]
The piezoelectric micropump according to the present invention includes a plurality of pump chambers arranged in parallel, and a part of the plurality of pump chambers is driven in a steady state, and a failure occurs in the pump chamber driven in the steady state. In this case, if at least a part of the remaining pump chamber is driven, it is possible to prevent the continuous operation from being hindered by a failure, so that the piezoelectric micro pump can have a redundant function.
[0074]
In addition, when the piezoelectric micropump according to the present invention includes a plurality of pump chambers arranged in series, and these pump chambers are driven with mutually different phases so as to perform peristaltic movement, the flow rate is not reduced due to pulsation. Stability can be prevented and flow stability can be secured.
[Brief description of the drawings]
FIG. 1 is a front view showing a cross section of a piezoelectric micropump 21 according to a first embodiment of the present invention.
FIG. 2 is a cross-sectional view taken along line AA in FIG.
FIG. 3 is a cross-sectional view taken along line BB in FIG.
FIG. 4 is a view corresponding to FIG. 3 for explaining a second embodiment of the present invention.
FIG. 5 is a view corresponding to FIG. 3 for explaining a third embodiment of the present invention.
FIG. 6 is a view corresponding to FIG. 3 for explaining a fourth embodiment of the present invention.
FIG. 7 is a front view showing a cross section of a conventional piezoelectric micropump 1 of interest to the present invention.
8 is a cross-sectional view taken along line CC in FIG.
FIG. 9 is a diagram for explaining a pump motion provided by the discharge side taper valve 10 and the supply side taper valve 11 shown in FIGS. 7 and 8;
[Explanation of symbols]
21, 21a, 21b, 21c Piezoelectric micropump 22 Si substrate 23 First main surface 25, 26 Buffer layer 28 Lower electrode layer 29 Piezoelectric thick film 30 Upper electrode layer 31 Diaphragm portion 32 Second main surface 33 Opening 34, 41, 42, 51, 52, 61-64 Pump chamber 35 Discharge side flow path 36 Supply side flow path 37 Discharge side taper valve 38 Supply side taper valve 39 Restriction part 40 Sealing layers 43, 69 Discharge side connection paths 44, 70 Supply side connection path 53, 65 Taper valve 54, 66, 68 Flow path

Claims (6)

Equipped with a substrate,
On the first main surface side of the substrate, a lower electrode layer, a piezoelectric thick film, and an upper electrode layer are laminated in this order,
The substrate is provided with a pump chamber in a state where a diaphragm portion is formed on the first main surface side and an opening is formed on the second main surface side opposite to the first main surface. A discharge side channel and a supply side channel communicating with the chamber are provided,
The opening is sealed by a sealing layer;
At least a part of each of the discharge side flow path and the supply side flow path is provided by a discharge side taper valve and a supply side taper valve, respectively.
The discharge side taper valve is provided with a throttle portion that serves as a boosting portion,
Piezoelectric micro pump. The piezoelectric micropump according to claim 1, wherein the substrate is a Si substrate, and a buffer layer is further formed between the Si substrate and the lower electrode layer. A plurality of pump chambers arranged in parallel, wherein at least the piezoelectric thick film and the upper electrode layer are provided in association with each of the plurality of pump chambers; The side flow paths each include a discharge side connection path and a supply side connection path that connect the plurality of pump chambers to each other, and the discharge side taper valve and the supply side taper valve are respectively connected to the discharge side connection path and The piezoelectric micropump according to claim 1, wherein the piezoelectric micropump is provided so as to communicate with the supply side connection path. A part of the plurality of pump chambers is driven in a steady state, and when a failure occurs in the pump chamber driven in the steady state, at least a part of the remaining pump chambers is driven. The piezoelectric micropump according to claim 3. A plurality of pump chambers arranged in series, wherein at least the piezoelectric thick film and the upper electrode layer are provided in association with each of the plurality of pump chambers; two adjacent pump chambers Is connected to each other by a flow path provided by a taper valve, and is provided such that the discharge flow path communicates with the pump chamber located on the most downstream side with respect to the flow direction of the fluid, and 5. The piezoelectric micro pump according to claim 1, wherein the supply-side flow path is provided so as to communicate with the pump chamber located on the most upstream side. The piezoelectric micropump according to claim 5, wherein the plurality of pump chambers are driven with phases different from each other so as to perform a peristaltic motion.

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