JP2010216398A - Piezoelectric pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a piezoelectric pump transferring fluid with sufficient stability. <P>SOLUTION: This piezoelectric pump includes: a structure having a piezoelectric element and a support member supporting the piezoelectric element; and a first substrate and a second substrate that sandwich the structure. The piezoelectric pump has: a pump chamber surrounded by the second substrate and the structure; and a first opening and a second opening that communicate with the pump chamber. The piezoelectric element includes: a displacement part displaced by application of a voltage; and a fixed part fixed by being directly or indirectly sandwiched between the first substrate and second substrate. From a state where the first substrate is joined to the structure, the portion of the first substrate, facing the displacement part and the surrounding part of the support member surrounding the periphery of the displacement part, is removed to expose the displacement part and the surrounding part. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a piezoelectric pump.

  Conventionally, various micropumps for transferring a very small amount of fluid have been studied. As one form thereof, a piezoelectric pump including a piezoelectric element as an actuator has been proposed. For example, Patent Document 1 discloses a silicon substrate that forms a fluid flow path for the purpose of providing a micropump capable of always delivering a constant discharge regardless of changes in external pressure and capable of bidirectional liquid feeding. A piezoelectric pump in which a piezoelectric element is disposed outside a (Si substrate) has been proposed. According to this piezoelectric pump, since the unimorph structure of the silicon substrate functioning as a diaphragm and the piezoelectric element is adopted, it can be manufactured very thin.

JP 10-299659 A

  However, the present inventors have examined the conventional piezoelectric pump as proposed in Patent Document 1 in detail, and such a conventional piezoelectric pump stably transfers fluid at a constant flow rate. I found it difficult. In particular, if the piezoelectric pump is to be miniaturized or thinned, it is difficult to accurately produce a piezoelectric pump capable of stably transferring a fluid. Therefore, there is a demand for such capability (transfer stability). Get higher.

  Accordingly, the present invention has been made in view of the above circumstances, and an object thereof is to provide a piezoelectric pump capable of transferring a fluid sufficiently stably.

  As a result of intensive studies to achieve the above object, the present inventors have found that the conventional piezoelectric pump cannot stably transfer the fluid due to the following factors. That is, in the conventional piezoelectric pump, as shown in FIG. 1 of Patent Document 1, for example, the entire piezoelectric element is attached to the movable part of the diaphragm. When the diaphragm operates in accordance with the displacement of the piezoelectric element, the piezoelectric element itself, which is the driving means for the operation, is fixed only to the diaphragm. For this reason, the inventors have found that the displacement of the piezoelectric element and the operation of the diaphragm interfere with each other, and as a result, the fluid cannot be stably transferred as a pump. If a part of the piezoelectric element is fixed so as not to be displaced, the piezoelectric element is displaced with the fulcrum as a fulcrum, and the displacement of the piezoelectric element is maintained stable even by the operation of the member functioning as a diaphragm. As a result of the inventors' finding and further studying in detail, the present invention has been completed.

  That is, the present invention includes a structure including a piezoelectric element and a support member that supports the piezoelectric element, and first and second substrates sandwiching the structure, and the second substrate and the structure. And a first and second openings communicating with the pump chamber, wherein the piezoelectric element is displaced by applying a voltage, and the first and first A fixed portion that is fixed by being directly or indirectly sandwiched between two substrates, and the first substrate is connected to the structure from the above-described displacement portion and the support member. Provided is a piezoelectric pump in which a portion facing the displacement portion and the surrounding portion is removed so as to expose the surrounding portion surrounding the outer periphery of the displacement portion.

  In the piezoelectric pump of the present invention having such a configuration, when a voltage is applied to the piezoelectric element, the piezoelectric body constituting the piezoelectric element is displaced in the in-plane direction (d31 direction) and the thickness direction (d33 direction). Along with this displacement, the structure vibrates in the thickness direction with the portion fixed to the first and / or second substrate as a fulcrum due to the shape effect with the support member. Due to this vibration, the volume and internal pressure of the pump chamber, which becomes a fluid flow path, change, whereby the fluid is transferred through the piezoelectric pump via the first opening, the pump chamber, and the second opening. .

  Further, in the piezoelectric pump of the present invention, even if a voltage is applied to the piezoelectric element, the fixed portion is fixed by being directly or indirectly held between the first and second substrates. The displacement is suppressed (restricted). Therefore, the piezoelectric element vibrates when the displacement portion is displaced with the fixed portion as a fulcrum. As a result, the disadvantages seen in the prior art as described above, that is, the interference between the operation of the support member functioning as a diaphragm and the displacement of the piezoelectric element is sufficiently suppressed. It can be transported stably.

  Further, in the piezoelectric pump of the present invention, the first substrate is displaced from the state bonded to the structure so that the displacement portion and the surrounding portion surrounding the outer periphery of the displacement portion in the support member are exposed. The part facing the part and the surrounding part is removed by etching. As a result, the displacement portion and the surrounding portion can release the tensile stress and the compressive stress (hereinafter simply referred to as “stress”) generated by being bonded and restrained to the first substrate to the outside. . On the other hand, the other parts of the first substrate are supported by being joined (as is) to the structure as it is. As a result, the structure can be fixed to the first substrate with high accuracy and reliability, so that the fluid can be transferred more stably.

  By the way, the structure in the piezoelectric pump is a portion that becomes a fulcrum of operation when the both sides of the structure are fixed rather than only one side (for example, the second substrate side in the present invention) is fixed. Therefore, the operation is naturally stable. In the case of a structure such as the piezoelectric pump of the present invention, as a method of fixing the structure by the first substrate, the structure is started from the state where nothing is bonded to that side, that is, the opposite side to the second substrate. A method of bonding the first substrate to a portion other than the operating portion, and once the first substrate is bonded to the entire surface of the first substrate, only the portion of the first substrate bonded to the operating portion is selectively removed. A method is considered.

  In the case of the former method, the first substrate is partially bonded to one side of the structure, so that the operating portion that is not bonded to the first substrate is partially relaxed or partially It will be pulled. As a result, the stress (distribution) in the operating portion is not uniform, and the operation varies accordingly. Therefore, it is difficult to stably transfer the fluid in the piezoelectric pump having such a structure. On the other hand, in the case of the piezoelectric pump having the latter structure according to the present invention, since the first substrate is bonded to the entire surface on one side of the structure, the entire surface of the structure is constrained by the first substrate and the stress (distribution) ) Becomes uniform. After that, even if the operation portion, that is, the portion of the first substrate bonded to the displacement portion and the surrounding portion is removed and the operation portion is exposed, the other portions are restrained by bonding with the first substrate. Has been. As a result, since the stress in the operating portion is continuously maintained uniformly, the piezoelectric pump of the present invention having such a structure can transfer the fluid sufficiently stably.

  Furthermore, since the piezoelectric pump of the present invention exposes not only the displacement portion of the piezoelectric element but also the surrounding portion of the support member that surrounds it, these operation portions can operate greatly (in other words, they can be displaced greatly). And the pump capacity can be increased.

  In the piezoelectric pump according to the aspect of the invention, the piezoelectric element includes a first electrode, a piezoelectric body, and a second electrode that are sequentially stacked from the first substrate side, and includes a first electrode that includes the first electrode and the piezoelectric body. This laminate preferably has a product of Young's modulus and thickness lower than those of the second electrode. In addition, the piezoelectric element further includes a hard layer on the second substrate side of the second electrode, and the first laminated body has a lower Young's modulus than the second laminated body including the second electrode and the hard layer. It is also preferable to have a product of thickness and thickness. By doing so, the operation part of the structure is more easily bent toward the first substrate side, and the degree of bending toward the second substrate side is reduced. Can be transported more stably.

  In the piezoelectric pump of the present invention, the hard layer is preferably made of at least one metal selected from the group consisting of chromium, tungsten, tantalum and platinum. Since these metals have a particularly high Young's modulus, for the same reason as described above, even if the hard layer is thinned, more stable fluid transfer is possible. Therefore, the piezoelectric pump can be made smaller and thinner. Is advantageous.

  ADVANTAGE OF THE INVENTION According to this invention, the piezoelectric pump which can transfer a fluid sufficiently stably can be provided.

It is process drawing which shows typically the manufacturing method of the piezoelectric pump of this embodiment. It is a top view which shows typically the plane shape of the piezoelectric element which concerns on this embodiment. It is process drawing which shows typically operation | movement of the piezoelectric pump of this embodiment. It is a top view which shows typically the piezoelectric pump of another this embodiment. It is process drawing which shows typically operation | movement of the piezoelectric pump of another this embodiment. It is the schematic sectional drawing which expanded the piezoelectric pump of another this embodiment partially. It is a figure which shows the sample in an Example typically. It is a plot figure which shows the grade of the bending of a structure at the time of changing the thickness of a hard layer. It is a top view which shows typically the piezoelectric pump of another this embodiment.

  Hereinafter, a form for carrying out the present invention (hereinafter simply referred to as “the present embodiment”) will be described in detail with reference to the drawings as necessary. In the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted. Further, the positional relationship such as up, down, left and right is based on the positional relationship shown in the drawings unless otherwise specified. Further, the dimensional ratios in the drawings are not limited to the illustrated ratios.

  FIG. 1 is a process diagram schematically showing a method of manufacturing the piezoelectric pump 170 according to the first embodiment. First, in the step (a1), the lower electrode layer 104, the piezoelectric layer 106, and the upper electrode layer 108 are laminated in this order on the first substrate 102 that also serves as a film formation substrate. More specifically, first, the lower electrode layer 104 is formed on the surface of the first substrate 102 by, for example, sputtering, CVD, or vapor deposition, and the lower electrode layer 104 is bonded to the first substrate 102. The first substrate 102 is not particularly limited as long as the lower electrode layer 104 and the piezoelectric layer 106 can be formed on the surface thereof, and may be a substrate used for normal thin film formation. However, the Si substrate is preferable from the viewpoint of the combination of the material of the piezoelectric layer 106 and the film forming method described later, and the viewpoint of obtaining a highly oriented piezoelectric body. The material of the lower electrode layer 104 is not particularly limited as long as it can be used as an electrode material of the piezoelectric element, and examples thereof include platinum, gold, copper, and alloys containing these. Further, the thickness of the lower electrode layer 104 is, for example, 0.05 μm to 1.0 μm.

  Next, a piezoelectric layer 106 is formed on the surface of the lower electrode layer 104 and, if necessary, the exposed surface of the first substrate 102. The formation method of the piezoelectric layer 106 may be a sputtering method, a CVD method, a vapor deposition method, or the like, but in particular, a film formation method utilizing epitaxial growth on a Si substrate has high orientation and excellent piezoelectric characteristics. This is preferable because a piezoelectric body can be obtained and the yield in manufacturing the piezoelectric pump 170 can be improved. Such a film forming method is disclosed in, for example, Japanese Patent Application Laid-Open No. 2000-332569 by the present applicant. The material of the piezoelectric layer 106 is not particularly limited as long as it is a piezoelectric material capable of forming a thin film, and examples thereof include PZT and barium titanate. Among these, PZT (lead zirconate titanate) is preferable from the viewpoint of showing excellent piezoelectric characteristics and being easily available. When PZT is adopted as the material of the piezoelectric layer 106 and it is formed by a film forming method using epitaxial growth on a Si substrate, it is particularly excellent to form a PZT (001) thin film on Si (100) by epitaxial growth. From the viewpoint of obtaining a good orientation. The thickness of the piezoelectric layer 106 is, for example, 0.5 μm to 5.0 μm.

  Subsequently, the upper electrode layer 108 is formed on the surface of the piezoelectric layer 106 by, for example, sputtering, CVD, or vapor deposition. The material of the upper electrode layer 108 is not particularly limited as long as it can be used as an electrode material of a piezoelectric element, and examples thereof include platinum, gold, copper, and alloys containing these. The thickness of the upper electrode layer 108 may be, for example, 0.05 μm to 1.0 μm.

  Next, in the step (a2), the lower electrode layer 104, the piezoelectric layer 106, and the upper electrode layer 108 laminated as described above are patterned into a desired shape. The patterning method is not particularly limited. For example, after a mask resist is formed on the surface of the upper electrode layer 108 as an etch mask, portions of the respective layers not covered with the mask resist are removed by etching, and then the mask is masked. The resist may be removed. As another patterning method, a lift-off method for resist patterning, film formation, and removal of unnecessary portions may be used. As a result, the piezoelectric element 120 including the lower electrode 114, the piezoelectric body 116, and the upper electrode 118 stacked in this order is obtained in a state of being bonded to the first substrate 102. In addition to / in place of the steps (a1) and (a2), the lower electrode layer 104, the piezoelectric layer 106, and the upper electrode layer 108 may be directly patterned together with the film formation, for example, by a laser drawing method. The piezoelectric element 120 may be obtained by performing film formation and patterning for each layer and repeating this.

  An example of the planar shape of the piezoelectric element 120 formed by patterning is the shape shown in FIG. FIG. 2 is a schematic view schematically showing a planar shape of the piezoelectric element 120 and a portion of the first substrate 102 to be removed by etching described later. As shown in FIG. 2B, if the piezoelectric element 120 has a planar shape having a throttle portion 120a, the piezoelectric element can be greatly displaced by applying a small voltage, and the flow rate of fluid can be increased. It becomes possible. However, as shown in FIG. 2A, the piezoelectric element 120 may have a planar shape having no diaphragm portion.

  Also, as shown in FIG. 2C, the piezoelectric element 120 may have a planar shape in which the width of the aperture portion gradually narrows in the in-plane direction toward the electrode extraction portion, as shown in FIG. As described above, the piezoelectric element 120 may have a circular planar shape. Furthermore, the piezoelectric body 116 in the piezoelectric element 120 and the planar shapes of the electrodes 114 and 118 may be the same or different. For example, in FIGS. 2A and 2B, the piezoelectric body 116 and the planar shapes of the electrodes 114 and 118 are substantially the same. On the other hand, as shown in FIGS. 2C and 2D, each of the electrodes 114 and 116 may have a planar shape in which a protrusion 120 b is further provided on the piezoelectric body 116. The protruding portion 120b can also function as an extraction portion for the electrodes 114 and 116. 2C and 2D, in place of the steps (a1) and (a2), the lower electrode layer 104 is formed and patterned, the piezoelectric layer 106 is formed and patterned, and the upper electrode layer is formed. The piezoelectric element 120 may be obtained through the formation 108 and the patterning process.

  The piezoelectric element 120 may have a throttle portion in the thickness direction in addition to / in place of the in-plane direction of the support member. Also according to this, in order to control the displacement in the in-plane direction and the thickness direction in a well-balanced manner according to the type of fluid to be transferred, it is possible to appropriately change the shape of the throttle portion.

  Next, in the step (a3), the insulating member 122 is formed on the surfaces of the first substrate 102 and the piezoelectric element 120. The insulating member 122 is a member constituting a support member of the piezoelectric pump. The material of the insulating member 122 is a material having an insulating property and is flexible because it is necessary to bend and follow appropriately without being damaged by the displacement of the piezoelectric element 120. It is preferable. When a material having flexibility is used as the material of the insulating member 122, the displacement of the piezoelectric element 120 can be transmitted well to the pump chamber, so that the efficiency (fluid transfer efficiency and operation efficiency) of the piezoelectric pump is increased. Specifically, the material of the insulating member 122 is preferably a resin material. When the material of the insulating member 122 is a resin material, in the step (a3), first, a resin composition (for example, a mixture of a resin and / or a monomer and a solvent) that is a raw material of the resin material is first substrate. 102 and the surface of the piezoelectric element 120 are applied. Next, the applied resin composition is solidified by drying or the like, or cured by heating or light irradiation, and then patterned into a desired shape. The patterning may be performed by a known method for patterning a resin material, for example, a photolithography method. The resin material is preferably a material that adheres well to the first substrate 102 and the piezoelectric element 120 and has good patternability such as developability, and examples thereof include silicone resin, polyimide, and parylene. The surface shape of the insulating member 122 obtained by patterning may be a shape suitable for the wall surface forming the pump chamber of the piezoelectric pump. In this way, a structure 124 including the piezoelectric element 120 and the insulating member 122 that supports the piezoelectric element 120 is obtained.

  Next, in the step (a4), the first substrate 102 is partially etched. The step (a4) will be specifically described with reference to FIG. 2 together with FIG. In the step (a4), the portion of the first substrate 102 facing the piezoelectric element 120 and the portion of the insulating member 122 facing the portion surrounding the outer periphery of the piezoelectric element 120 are removed by etching, so that the opening 112 is formed. Form. In FIG. 2, a portion surrounded by a one-dot chain line is an opening 112 of the first substrate 102. As a result, a part of the surface of the piezoelectric element 120 on the molding substrate 102 side and a part of the surface of the insulating member 122 on the molding substrate 102 side are exposed. A part of the piezoelectric element 120 whose surface is exposed functions as a displacement part 120c described later, and a part where the surface of the piezoelectric element 120 is not exposed functions as a fixed part 120d. Further, a part of the insulating member 122 whose surface is exposed is an enveloping portion 122 a that surrounds the displacing portion 120 c of the piezoelectric element 120, and can be expanded and contracted by the displacement of the piezoelectric element 120.

  The etching method is not particularly limited. For example, after a mask resist having a predetermined shape is formed on the surface of the first substrate 102 as an etch mask, the portion of the first substrate 102 that is not covered with the mask resist by etching. Then, the mask resist may be removed. Other etching methods include resist patterning, film formation, and lift-off method for removing unnecessary portions. The etching is preferably dry etching, and examples thereof include reactive gas etching, reactive ion etching, reactive ion beam etching, ion beam etching, and reactive laser beam etching. In this manner, a first composite 126 including the first substrate 102 having the opening 112, the piezoelectric element 120 formed by bonding to the first substrate 102, and the insulating member 122 is obtained.

  On the other hand, in the step (b1), first, a material substrate 130 is prepared. Examples of the material substrate 130 include a glass substrate and a ceramic substrate, and the thickness thereof is, for example, 0.2 mm to 2.0 mm. Subsequently, in the step (b2), the surface of the material substrate 130 is processed into a predetermined shape by etching or the like. Further, in the step (b3), the first opening 130a and the second opening 130b penetrating in the thickness direction are formed at predetermined positions of the material substrate 130 by etching or the like. Thus, a second substrate 132 having openings 130a and 130b is obtained. Here, the surface shape of the second substrate 132 obtained by processing may be a shape suitable for the wall surface forming the pump chamber of the piezoelectric pump.

  Next, in step (c), the second substrate 132 is attached to the side of the first composite 126 where the insulating member 122 is formed. At this time, the second substrate 132 is aligned so that the surface processed by etching or the like faces the first composite 126 and the openings 130a and 130b communicate with the pump chamber of the piezoelectric pump. And paste. Examples of the attaching method include a method in which an adhesive or a resin is applied and attached to a portion where the first composite 126 and the second substrate 132 are in contact with each other. Thus, the piezoelectric pump 170 of this embodiment is obtained.

  The obtained piezoelectric pump 170 according to the present embodiment includes a structure 124 that includes a plurality of piezoelectric elements 120 and an insulating member 122 that is a support member that supports the piezoelectric elements 120, and first and second structures that directly sandwich the structure 124. A pump chamber 178 containing the second substrates 102 and 132 and surrounded by the second substrate 132 and the structure 124; and first and second openings 130a and 130b communicating with the pump chamber 178; It is what has. The piezoelectric element 120 includes a displacement portion 120c that is displaced by applying a voltage, and a fixed portion 120d that is fixed by being held between the first and second substrates 102 and 132. The insulating member 122 has a surrounding portion 122 a that surrounds the outer periphery of the displacement portion 120 c of the piezoelectric element 120. The displacement portion 120c and the surrounding portion 122a are exposed at the surface on the first substrate 102 side. In addition, the first substrate 102 has an opening 112 formed by removing a portion facing the displacement portion 120c and the surrounding portion 122a.

  More specifically, the structure 124 contained in the piezoelectric pump 170 of this embodiment includes a plurality of piezoelectric elements 120 and an insulating member 122 that is directly bonded to and supported by the piezoelectric elements 120. The insulating member 122 includes a film-like portion 122 b bonded to the second substrate side of the piezoelectric element 120 and a peripheral edge portion 122 c surrounding the thin film portion and the piezoelectric element 120. A portion of the peripheral edge portion 122c whose surface is exposed on the first substrate 120 side is the surrounding portion 122a. The piezoelectric element 120 has a thin film shape and is disposed so as to be embedded under the film-like portion 122b of the insulating member 122. The insulating member 122 covers the surface of the piezoelectric element 120 on the pump chamber (flow path) 178 side. Are joined together.

  The upper surface of the first substrate 122 is bonded to the lower surface of a portion where the structure 124 does not operate. On the other hand, the second substrate 132 may be in contact with a part of the insulating member 122 forming the pump chamber 178 in a state where the piezoelectric pump 170 is not operated, but is not bonded at that part. The second substrate 132 has first and second openings 130 a and 130 b that penetrate in the thickness direction, and these openings 130 a and 130 b communicate with the pump chamber 178. A part of the plurality of piezoelectric elements 120 is disposed below the openings 130 a and 130 b of the second substrate 132. The film-like portion 122b of the insulating member 122 located between the piezoelectric element 120 and the openings 130a and 130b closes the openings 130a and b when the piezoelectric pump 170 does not operate.

  Next, an operation method of the piezoelectric pump 170 of this embodiment will be described. In the piezoelectric pump 170 of this embodiment, when a voltage is applied to the thin film piezoelectric body 116, the piezoelectric element 120 is displaced in the in-plane direction (d31 direction) and the thickness direction (d33 direction). In particular, the piezoelectric element 120 has a thin film shape, and the periphery of the structure 124 is fixed by the first and second substrates 102 and 132. To curve. Then, the structure 174 is fixed to the first and second substrates 102 and 132 by turning on / off the voltage application or switching the direction of the applied voltage between the forward direction and the reverse direction (applying an alternating voltage). The vertical movement is repeated in the thickness direction with the peripheral edge of the structure 124 as a fulcrum. By this operation, the volume and internal pressure of the pump chamber 178 that is also a flow path are changed, so that the fluid is transferred through the piezoelectric pump 170 through the first opening 130a, the pump chamber 178, and the second opening 130b in this order. Is done.

  The operation method of the piezoelectric pump 170 of this embodiment will be described in more detail with reference to FIG. First, in step (a), the piezoelectric pump 170 is in a stopped state, and the upper surface of the structure 124 is in contact with the second substrate 132. Thereby, the openings 130 a and 130 b are closed by the insulating member 122 that forms the pump chamber 178. Next, in step (b), a voltage is applied to the most upstream piezoelectric element 120 x among the plurality of piezoelectric elements 120. Then, along with the displacement of the piezoelectric body 122 in the piezoelectric element 120x, the piezoelectric element 120x is bent downward along with the insulating member 122, and the insulating member 122 is pulled downward due to the bending, and the second substrate 132 and Separate. As a result, the pump chamber 178 becomes negative pressure and communicates with the outside via the first opening 130a, so that the piezoelectric pump 170 sucks fluid into the pump chamber 178 from the first opening 130a.

  Next, in step (c), the voltage is applied to the middle-stream piezoelectric element 120y and the voltage application to the most upstream piezoelectric element 120x is stopped. Then, along with the displacement of the piezoelectric body 122 in the piezoelectric element 120y, the piezoelectric element 120y is bent downward along with the insulating member 122, and the insulating member 122 is pulled downward due to the bending, and the second substrate 132 and Separate. Further, the piezoelectric element 120x returns to the stopped state and comes into contact with the insulating member 122 again to close the first opening 130a. As a result, the pump chamber 178 above the piezoelectric element 120x is pressurized and the pump chamber 178 above the piezoelectric element 120y has a negative pressure. Therefore, the piezoelectric pump 170 moves the fluid in the pump chamber 178 downstream. Extrude to the side. Further, in order to close the first opening 130a, the suction of fluid from the outside is temporarily stopped.

  Subsequently, in step (d), the voltage is applied to the most downstream piezoelectric element 120z and the voltage application to the middle-stream piezoelectric element 120y is stopped. Then, along with the displacement of the piezoelectric body 122 in the piezoelectric element 120z, the piezoelectric element 120z is bent downward along with the insulating member 122, and the insulating member 122 is pulled downward due to the bending, and the second substrate 132 and Separate. Further, the piezoelectric element 120y returns to the stopped state and comes into contact with the insulating member 122 again. As a result, the portion of the pump chamber 178 above the piezoelectric element 120y is pressurized and the portion of the pump chamber 178 above the piezoelectric element 120z becomes negative pressure, so that the piezoelectric pump 170 further supplies the fluid in the pump chamber 178. Extrude downstream. Further, since the pump chamber 178 communicates with the outside via the second opening 130b, the piezoelectric pump 170 discharges fluid from the pump chamber 178 to the outside via the second opening 130b.

  By repeating the above steps, the fluid can be transferred by the piezoelectric pump 170 of the present embodiment. In this case, for example, the step (b) may be started together with the start of the step (d). Thereby, the amount of fluid transferred per unit time by the piezoelectric pump 170 can be further increased.

  In the piezoelectric pump 170 of this embodiment, even if a voltage is applied to the piezoelectric element 120, the fixed portion 120 d is fixed by being directly held between the first and second substrates 102 and 132. Therefore, the displacement is suppressed. On the other hand, the displacement portion 120 c of the piezoelectric element 120 is not sandwiched between the first and second substrates 102 and 132. Therefore, the piezoelectric element 120 vibrates when the displacement portion 120c is favorably displaced with the fixed portion 120d as a fulcrum. As a result, interference between the operation of the insulating member 122 functioning as a diaphragm and the displacement of the piezoelectric element 120 is sufficiently suppressed as compared with the conventional case, and the piezoelectric pump 170 can stably transfer the fluid.

  Further, in the piezoelectric pump 170, the first substrate 102 is exposed to the displacement portion 120c and the surrounding portion 122a that surrounds the outer periphery of the displacement portion 120c of the insulating member from the state bonded to the structure 124. A portion facing the displacement portion 120c and the surrounding portion 122a is removed by etching. Thereby, the displacement part 120c and the surrounding part 122a can release the stress which has arisen by joining and restraining on the 1st board | substrate 102 by vapor deposition etc. As shown in FIG. On the other hand, the other parts of the first substrate 102 are joined and supported by the structure 124 as they are. As a result, the structure 124 can be fixed to the first substrate 102 with high accuracy and reliability, so that the piezoelectric pump 170 can transfer the fluid more stably.

  When manufacturing the piezoelectric pump 170 of this embodiment, the entire surface of one side of the structure 124 is temporarily bonded to the first substrate. Since the piezoelectric pump is mainly formed by a thin film method, each member constituting the structure 124 is joined to another member in a relatively high temperature environment such as a vapor deposition method, or the member is an insulating member 122. Are joined by applying a molten resin. Subsequent cooling causes the structure 124 to shrink, but since the entire surface is constrained by the first substrate 102, the stress (distribution) becomes uniform at a high level. Next, portions of the first substrate 102 bonded to the piezoelectric element 120 displacement portion 120c and the surrounding portion 122a of the insulating member 122 are removed by etching. Even if these portions are exposed, the other portions are the first portion. Restrained by bonding with the substrate 102. As a result, the stress in the displacement portion 120c and the surrounding portion 122a is continuously maintained at a high level, so that the piezoelectric pump 170 can transfer the fluid sufficiently stably and at a large flow rate.

  Further, in the piezoelectric pump 170, not only the displacement portion 120c of the piezoelectric element 120 but also the surrounding portion 122a of the insulating member 122 surrounding the piezoelectric element 120 is exposed, so that those portions can be operated greatly and the pump capacity can be increased. It becomes possible.

  The piezoelectric pump 170 according to the present embodiment sequentially applies a voltage to the plurality of piezoelectric elements 120 from the upstream side to the downstream side in the fluid flow direction. As a result, the piezoelectric element 120 is moved as a whole (moving) to transfer the fluid. In general, a thin-film piezoelectric element has a small pump capacity, a displacement amount of the piezoelectric element is not large, and an internal pressure of the pump chamber cannot be increased so much, and therefore it is difficult to increase a fluid transfer amount. However, according to the piezoelectric pump 170 of the present embodiment, the fluid is transferred by operating the plurality of piezoelectric elements 120 as a whole in a peristaltic manner as described above. As described above, the transfer amount of the liquid per one piezoelectric element can be increased at least by simultaneously operating a plurality of piezoelectric elements. In particular, the piezoelectric element on the upstream side is returned from the bent state to the original state to pressurize the corresponding pump chamber portion, and at the same time, the piezoelectric element on the downstream side is bent downward and the corresponding pump chamber By depressurizing this portion, a large transfer amount can be realized with a smaller voltage, so that the efficiency of the piezoelectric pump 170 becomes very high.

  Furthermore, since the pump chamber 178 is surrounded by the second substrate 132 and the structural body 124 in the piezoelectric pump 170 of the present embodiment, the displacement of the plurality of piezoelectric elements 120 in the pump chamber 178 can be efficiently performed. It can be converted into compression (pressurization) and expansion (decompression). In addition, since the fluid can move through the pump chamber 178 from the upstream side to the downstream side, the compression and expansion can be efficiently converted into fluid transfer between the pump chambers. As a result, the piezoelectric pump 170 can more efficiently convert the voltage applied to the piezoelectric element 120 into a fluid transfer amount.

  In the piezoelectric pump 170 of the present embodiment, each of the plurality of piezoelectric elements 120 includes a pair of electrodes (lower electrode 114 and upper electrode 118). Is not large, and the bending range of the electrode accompanying the displacement of the piezoelectric element 120 does not increase. Therefore, the piezoelectric pump 170 can sufficiently suppress electrode peeling. In addition, the piezoelectric pump 170 of this embodiment includes a plurality of piezoelectric elements 120 supported by one insulating member 12, and a voltage applied to any one of the piezoelectric elements 120 causes displacement of the other piezoelectric elements 120. Does not affect. Therefore, the piezoelectric pump 170 can be operated sufficiently stably during high-speed driving, and variations in the displacement amount of the piezoelectric element 120 can be sufficiently suppressed.

  In addition, the piezoelectric pump 170 according to the present embodiment can be manufactured in an optimum shape according to the design as compared with a so-called bulk piezoelectric pump by making the piezoelectric element 120 into a thin film shape. Furthermore, by adopting the thin film piezoelectric element 120, the piezoelectric pump can be further reduced in size and layered as compared with the bulk piezoelectric pump. Therefore, the piezoelectric pump 170 can realize further high-density integration of electronic components including the piezoelectric pump 170, and can be effectively used for products to which the MEMS technology is applied.

In the piezoelectric pump 170 of the present embodiment, it is preferable that the lower electrode 114, the piezoelectric body 116, and the upper electrode 118 constituting the piezoelectric element 120 satisfy the following relationship. That is, it is preferable that the laminated body including the lower electrode 114 and the piezoelectric body 116 has a product of Young's modulus and thickness lower than those of the upper electrode 118. That is, if the Young's modulus of the laminate is E1 (N / m ² ), the thickness is D1 (nm), the Young's modulus of the upper electrode 118 is E2 (N / m ² ), and the thickness is D2 (nm). It is preferable that the condition represented by the following formula (1) is satisfied.
E1 × D1 <E2 × D2 (1)

  The product of the Young's modulus and the thickness of a member is one of the indices that represent the hardness of the member. When this index satisfies the condition expressed by the above formula (1), the operating portion of the structure 124 is more easily bent toward the first substrate 102 side, while the degree of bending toward the second substrate 132 side is low. Become. This is because the upper electrode 118 is harder than the laminated body and is difficult to extend or bend.

  As described above, the piezoelectric pump 170 of the present embodiment transfers fluid by the piezoelectric element 120 being bent downward. On the other hand, when the piezoelectric pump 170 is stopped, since the structure 124 and the second substrate 132 are in contact with each other in the pump chamber 178, it is difficult for the piezoelectric element 120 to bend upward, and the piezoelectric pump 120 operates normally. It becomes difficult to do. Therefore, by selecting the material and thickness of each member so that the piezoelectric element 120 satisfies the above formula (1), the piezoelectric pump 170 can be operated more stably and the fluid can be more stably transferred. it can.

The Young's modulus is a sample obtained by forming a thin film having a thickness of 100 nm on a reference substrate having a known Young's modulus under conditions of room temperature and 10 ⁻⁴ Pa. It can be measured by an elastic method (for example, using an ultra-thin film Young's modulus measuring device manufactured by ALOtec). At that time, when the thin film is a laminated body, the measurement is performed with the same thickness ratio as the thickness ratio of each member of the laminated body constituting the piezoelectric element.

In the piezoelectric pump 170 of the present embodiment, it is preferable that the piezoelectric element 120 further includes a hard layer (not shown) on the second substrate 132 side of the upper electrode 118. The hard layer has a Young's modulus lower than that of the stacked body (first stacked body) composed of the lower electrode 114 and the piezoelectric body 116 than the stacked body of the upper electrode 118 and the hard layer (second stacked body). The material and thickness are set to have a product of the thickness. That is, the Young's modulus of the first laminate is E1 (N / m ² ), the thickness is D1 (nm), the Young's modulus of the second laminate is E3 (N / m ² ), and the thickness is D3 ( nm), it is preferable that the condition represented by the following formula (2) is satisfied.
E1 × D1 <E3 × D3 (2)

Even if the condition represented by the above formula (2) is satisfied, the operating portion of the structure 124 is more likely to bend more easily on the first substrate 102 side, while the degree of the bend toward the second substrate 132 side is reduced. . This is because the second laminated body is harder than the first laminated body, and is difficult to extend or bend. When the piezoelectric element 120 satisfies the above formula (2), the piezoelectric pump 170 operates more stably, and the fluid can be transferred more stably. To satisfy the above equation (2) ensures the hard layer, a chromium (Cr; To a Young's modulus which is derived as described above (the same applies hereinafter) = 248N / m ^2), tungsten (W; 345N / m ² ), Tantalum (Ta; 186 N / m ² ) and platinum (Pt; 152 N / m ² ).

  In the step (a1), the hard layer is formed by further forming a layer of a material constituting the hard layer on the surface of the upper electrode layer 108 by, for example, a sputtering method, a CVD method, or a vapor deposition method, and in the step (a2) The layer is obtained by patterning together with the lower electrode layer 104, the piezoelectric layer 106, and the upper electrode layer.

  Next, the piezoelectric pump of the second embodiment will be described. FIG. 4 is a perspective plan view schematically showing the piezoelectric pump of this embodiment. FIG. 5 is a schematic view showing the operation of the piezoelectric pump according to the second embodiment. FIG. 5A schematically shows a cross section that appears when the piezoelectric pump is cut along the line II-II shown in FIG. Show. FIG. 6 is a schematic cross-sectional view showing a partially enlarged piezoelectric pump according to the second embodiment. The piezoelectric pump 200 according to the second embodiment has six piezoelectric elements 202, 204, 206, 208, 210, 212 (summary) arranged along the fluid flow direction (the direction of arrow A in FIG. 4). And the same, and so on), and a structure 220 having one support member 214 that supports the piezoelectric elements 202 to 212, and a first and a second that sandwich the structure 220. A pump chamber 230 containing the substrates 222 and 224 and surrounded by the second substrate 224 and the structure 220, and first and second openings 250 communicating with the pump chamber 230 during operation, 252. The piezoelectric elements 202 to 212 include displacement parts 202c to 212c that are displaced by applying a voltage, and fixed parts 202d to 212d that are fixed by being sandwiched between the first and second substrates 222 and 224. , 202e to 212e. Further, the first substrate 222 is displaced from the state where the first substrate 222 is bonded to the structure 220 such that the displacement portions 202c to 212c and the surrounding portion 214a surrounding the outer periphery of the displacement portions 202c to 212c in the support member 214 are exposed. A portion facing 202c to 212c and the surrounding portion 214a is removed by etching to form an opening 222a. The displacement parts 202c to 212c and the surrounding part 214a constitute an operation part of the structure.

  More specifically, the structure 220 contained in the piezoelectric pump 200 of the present embodiment includes the six piezoelectric elements 202 to 212 and one support member 214 that is directly joined to and supported by the piezoelectric elements 202 to 212. With. The support member 214 is a thin film made of resin, for example, and having a thickness of 1.0 μm to 10 μm. A portion 214a facing the pump chamber 230 on one main surface (upper surface) of the support member 214 has a planar shape like a so-called rosary chain in which six circular surfaces arranged in a row overlap each other at a part of the periphery. Have.

  The piezoelectric elements 202 to 212 are, for example, a thin film with a thickness of 0.5 μm to 10.0 μm and have a circular main surface. As shown in FIG. 6, each of the piezoelectric elements 202 a to 212 a (however, the piezoelectric element) The lower electrodes 210a and 212a included in the 210 and 212 are not shown.), The piezoelectric bodies 202b to 212b (however, the piezoelectric bodies 210b and 212b included in the piezoelectric elements 210 and 212 are not shown), and the upper electrodes 202c to 202c. 212c (however, upper electrodes 210c and 212c included in the piezoelectric elements 210 and 212 are not shown) are stacked in this order. Each of the piezoelectric elements 202 to 212 is embedded in the support member 214 with the lower electrodes 202a to 212a exposed to the opening 222a. The piezoelectric elements 202 to 212 are not in direct contact with each other, and the lower surface of the support member 214 is exposed between them.

  The first substrate 222 has an opening 222 a so as to expose the lower surface of the operating portion of the structure 220, and is bonded to a portion other than the operating portion of the structure 220. Here, the portion of the structure 220 bonded to the first substrate 222 is the lower surface of the support member 214. In addition, the second substrate 224 has a part of its lower surface joined to a part of the upper surface of the support member 214. Accordingly, the structure 220 including the support member 214 is nipped and fixed to the first and second substrates 222 and 224.

  When the piezoelectric pump is stopped, the second substrate is in contact with the upper surface of the operating portion of the structure 220 but not bonded. The second substrate 224 is provided with first and second openings 250 and 252 penetrating in the thickness direction, and these openings can communicate with the pump chamber 230 when the piezoelectric pump 200 is operated. The pump chamber 230 has partial pump chambers 232, 234, 236, 238, 240, 242 corresponding to the piezoelectric elements 202 to 212.

  Two ridge wirings 202d to 212d are taken out from each of the lower electrodes 202a to 212a provided in the six piezoelectric elements 202 to 212, and one ridge wiring 202e to 212e is taken from the upper electrodes 202c to 212c. It is taken out one by one. These wirings are also the fixed parts 202d to 212d and 202e to 212e as described above. The extracted wires 202d to 212d and 202e to 212e extend to the terminal 260, and are connected to a power source (not shown) through the terminal 260. Here, the connection part between each set of electrodes and wiring is a connection part between the lower electrode and the wiring, a connection part between the upper electrode and the wiring, a lower electrode and the wiring from the upstream side in the fluid flow direction. Are arranged in the order of the connecting parts. For example, when looking at the connection portions 202f and 202h between the lower electrode 202a and the two wires 202d and the connection portion 202g between the upper electrode 202c and the wire 202e, the connection portion 202f from the upstream side along the fluid flow direction. , 202h, 202g are arranged in this order. The same applies to the other connecting portions (204f to 204h, 206f to 206h, 208f to 208h, 210f to 210h, 212f to 212h).

  The piezoelectric pump 200 is manufactured as follows, for example.

  First, on the first substrate 222 that also serves as a film formation substrate, lower electrodes 202a to 212a each including protrusion wirings 202d to 212d, piezoelectric bodies 202b to 212b, and upper electrodes each including protrusion wirings 202e to 212e. 202c to 212c are stacked in this order. More specifically, first, layers to be the lower electrodes 202a to 212a are formed on the surface of the first substrate by, for example, a sputtering method, a CVD method, or a vapor deposition method. The first substrate 222 is not particularly limited as long as a layer to be the lower electrodes 202a to 212a can be formed on the surface thereof, and may be a substrate used for normal thin film formation, and is a Si substrate. And preferred. The material of the layer to be the lower electrodes 202a to 212a is not particularly limited as long as it can be used as the electrode material of the piezoelectric element, and examples thereof include platinum, gold, copper, and alloys containing these. Moreover, the thickness of the layer used as the lower electrodes 202a-212a is 0.05 micrometer-1.0 micrometer, for example.

  Next, the layer to be the lower electrodes 202a to 212a is patterned into a desired shape. The patterning method is not particularly limited. For example, after forming a mask resist on the surface of the layer to be the upper electrode as an etch mask, the portion of the layer not covered with the mask resist is removed by etching, and then The mask resist may be removed. Thereby, lower electrodes 202a to 212a are obtained.

  Next, piezoelectric bodies 202b to 212b are formed on the surfaces of the lower electrodes 202a to 212a (except for the surfaces of the wirings 202d to 212d). Examples of the method for forming the piezoelectric bodies 202b to 212b include a sputtering method, a CVD method, and a vapor deposition method. The material of the piezoelectric bodies 202b to 212b is not particularly limited as long as it is a piezoelectric material capable of forming a thin film, and examples thereof include PZT and barium titanate. Among these, PZT (lead zirconate titanate) is preferable from the viewpoint of showing excellent piezoelectric characteristics and being easily available. The thickness of the piezoelectric bodies 202b to 212b is, for example, 0.5 μm to 5.0 μm.

  Subsequently, upper electrodes 202c to 212c are formed on the surfaces of the piezoelectric bodies 202b to 212b by, for example, a sputtering method, a CVD method, or a vapor deposition method. The material of the upper electrodes 202c to 212c is not particularly limited as long as it can be used as the electrode material of the piezoelectric element, and examples thereof include platinum, gold, copper, and alloys containing these. The thickness of the upper electrodes 202c to 212c is, for example, 0.05 μm to 1.0 μm.

  When the piezoelectric bodies 202b to 212b and the upper electrodes 202c to 212c are formed, for example, after a resist having a predetermined shape is formed on the upper electrodes 202c to 212c, the piezoelectric bodies 202b to 212b and the upper electrodes 202c to 212c are sequentially formed. The resist may be removed. Thus, the piezoelectric elements 202 to 212 are obtained by laminating the lower electrodes 202a to 212a, the piezoelectric bodies 202b to 212b, and the upper electrodes 202c to 212c in this order on the first substrate 222.

  Next, a layer that becomes the support member 214 is formed so as to cover the piezoelectric elements 202 to 212. The material of this layer is an insulating material, and since it is necessary to bend without being damaged even by displacement of the piezoelectric bodies 202b to 212b, a material having flexibility is preferable. When a material having flexibility is employed as the material of the layer that becomes the support member 214, the displacement of the piezoelectric bodies 202b to 212b can be satisfactorily transmitted to the pump chamber 230, so that the efficiency of the piezoelectric pump 200 is increased. Specifically, the material of the layer to be the support member 214 is preferably a resin material. In this case, first, a resin composition (for example, a mixture of a resin and / or a monomer and a solvent) serving as a raw material for the resin material is applied on the surfaces of the first substrate 222 and the piezoelectric elements 202 to 212. Next, the applied resin composition is solidified by drying or the like and cured by heating or light irradiation. Thereafter, the cured resin composition is patterned into a desired shape as necessary. The patterning may be performed by a known method for patterning a resin material, for example, a photolithography method. The resin material is preferably a material that adheres well to the film formation substrate and the piezoelectric elements 202 to 212 and has good patternability such as developability, and examples thereof include silicone resin, polyimide, and parylene. In this way, a structure 220 including the piezoelectric elements 202 to 212 and the support member 214 formed on the film formation substrate is obtained.

  Separately from the structure body 220 described above, the second substrate 224 is manufactured. The second substrate 224 is obtained from a glass substrate and a ceramic substrate having a thickness of 0.2 mm to 2.0 mm, for example. The substrate surface is processed into a predetermined shape by etching or the like (unevenness processing), and a first opening 250 and a second opening 252 penetrating in the thickness direction are formed at a predetermined position of the substrate by etching or the like. To do. In this way, the second substrate 224 having the openings 250 and 252 and having a predetermined shape on the lower surface thereof is obtained.

Next, a second substrate 224 is attached to the structure body 220. At this time, the lower surface of the second substrate 224 that has been subjected to the uneven processing and the surface of the structure 220 on the side on which the support member 214 is formed are opposed to each other and the pump chamber 230 is formed. The lower surface of the second substrate 224 and the support member 214 are bonded and bonded around the portion to be the pump chamber 230. However, the second substrate 224 is only brought into contact with the surrounding portion 214a of the support member 214 as well as the displacement portions 202c to 212c constituting the operation portion, and they are not joined. Examples of the attaching method include a method in which an adhesive is applied and attached to a portion where the support member 214 and the second substrate 224 are in contact with each other.
Next, the first substrate 222 is partially etched. Specifically, a portion of the first substrate 222 facing the operation portion is removed by etching to form an opening 222a. Thereby, the surface of the displacement parts 202c-212c which are an operation | movement part, and the surrounding part 214a is exposed. They can expand and contract and bend as the piezoelectric elements 202 to 212 are displaced.

  The etching method is not particularly limited. For example, after a mask resist having a predetermined shape is formed on the surface of the first substrate 222 as an etch mask, the portion of the first substrate 222 that is not covered with the mask resist by etching. Then, the mask resist may be removed. Other etching methods include resist patterning, film formation, and lift-off method for removing unnecessary portions. The etching is preferably dry etching, and examples thereof include reactive gas etching, reactive ion etching, reactive ion beam etching, ion beam etching, and reactive laser beam etching.

Thus, the piezoelectric pump 200 of the second embodiment is obtained.
As described above, since the piezoelectric pump 200 according to the present embodiment is manufactured based on a so-called thin film process, it is possible to suppress variation in quality, increase the yield, and reduce the manufacturing cost. is there.

  Next, an operation method of the piezoelectric pump 200 of the present embodiment will be described with reference to FIG. First, in step (a), the piezoelectric pump 200 is in a stopped state, and the upper surface of the structure 220 is in contact with the second substrate 224. Thereby, the first and second openings 250 and 252 are closed by the support member 214 forming the pump chamber 230. Next, in step (b), a voltage is applied between the wiring 202d from the lower electrode 202a of the piezoelectric element 202 via the connecting portion 202h and the upper electrode 202c from the wiring 202e via the connecting portion 202g, and at the same time, the wiring 204d. A voltage is applied between the lower electrode 204a of the piezoelectric element 204 through the connecting portion 204f and the upper electrode 204c through the connecting portion 204g from the wiring 204e. Then, as the piezoelectric bodies 202b and 204b are displaced, the piezoelectric elements 202 and 204 simultaneously bend downward along with the supporting member 214, and the bending causes the supporting member 214 above and between the piezoelectric elements 202 and 204 to be bent. The support member 214 and the second substrate 224 are separated from each other by being pulled downward. Accordingly, since the pump chambers 232 and 234 have negative pressure, the piezoelectric pump 200 sucks fluid into the pump chambers 232 and 234 from the first opening 250. It should be noted that the top of the curved piezoelectric element 202 is a portion that is slightly closer to the virtual connecting portion at the midpoint between the connecting portion 202h and the connecting portion 202g than the central portion in the in-plane direction. Is a portion slightly closer to a virtual connecting portion at a midpoint between the connecting portion 204f and the connecting portion 204g than the center portion in the in-plane direction.

  Next, in step (c), application of voltage between the lower electrode 202a and the upper electrode 202c is stopped, and the lower electrode 204a of the piezoelectric element 204 is connected from the wiring 204d via the connecting portion 204h, and the connecting portion is connected from the wiring 204e. A voltage is applied between the upper electrode 204c via 204g and at the same time between the lower electrode 206a of the piezoelectric element 206 from the wiring 206d via the connecting portion 206f and the upper electrode 206c from the wiring 206e via the connecting portion 206g. Apply voltage to Then, the piezoelectric element 202 returns to the stopped state, and the structure 220 and the support member 214 come into direct contact again above and between the piezoelectric elements 202 and 204, and the piezoelectric element 206 is supported by the displacement of the piezoelectric body 206b. Curved downward with member 214. Further, the bending causes the support member 214 above and between the piezoelectric elements 204 and 206 to be pulled downward, and the structure 220 and the support member 214 are separated from each other at that portion. As a result, the pump chamber 232 is pressurized and the pump chamber 236 has a negative pressure. Therefore, the piezoelectric pump 200 pushes out the fluid in the pump chamber 232, while sucking the fluid into the pump chamber 236. Transfer further downstream. In addition, since the voltage application to the lower electrode 204a is switched from the connection portion 204f to the connection portion 204h, the top of the curved piezoelectric element 204 is connected to the connection portion 204f and the connection portion 204g rather than the central portion in the in-plane direction. From the portion slightly approaching the virtual connecting portion at the intermediate point to the portion slightly approaching the virtual connecting portion at the intermediate point between the connecting portion 204h and the connecting portion 204g, that is, the downstream side in the fluid flow direction. As a result, the fluid is pushed downstream in the pump chamber 234, so that the downstream transfer of the fluid is further promoted.

  Subsequently, in step (d), application of voltage between the lower electrode 204a and the upper electrode 204c is stopped, and the lower electrode 206a of the piezoelectric element 206 is connected to the wiring 206e from the wiring 206d through the connecting portion 206h. A voltage is applied to the upper electrode 206c through the portion 206g, and at the same time, the lower electrode 208a of the piezoelectric element 208 from the wiring 208d through the connecting portion 208f, and the upper electrode 208c from the wiring 208e through the connecting portion 208g. A voltage is applied between them. Then, the piezoelectric element 204 returns to the stopped state, and the structure 220 and the support member 214 come into direct contact again above and between the piezoelectric elements 204 and 206, and the piezoelectric element 208 is moved along with the displacement of the piezoelectric body 208b. It curves downward with the support member 214. Also, due to the bending, the support member 214 above and between the piezoelectric elements 206 and 208 is pulled downward, and the structure 220 and the support member 214 are separated from each other at that portion. As a result, the pump chamber 234 is pressurized and the pump chamber 238 has a negative pressure. Therefore, the piezoelectric pump 200 pushes out the fluid in the pump chamber 234, while sucking the fluid into the pump chamber 238, Transfer further downstream. In addition, since the voltage application to the lower electrode 206a is switched from the connection portion 206f to the connection portion 206h, the top portion of the curved piezoelectric element 206 is connected to the connection portion 206f and the connection portion 206g rather than the central portion in the in-plane direction. From the part slightly approaching the virtual connecting part at the intermediate point to the part slightly approaching the virtual connecting part at the intermediate point between the connecting part 206h and the connecting part 206g, that is, downstream in the fluid flow direction. As a result, the fluid is pushed downstream in the pump chamber 236, so that the downstream transfer of the fluid is further promoted.

  Next, in the step (e), the application of voltage between the lower electrode 206a and the upper electrode 206c is stopped, and the lower electrode 208a of the piezoelectric element 208 is connected from the wiring 208e via the connecting portion 208h from the wiring 208d. A voltage is applied to the upper electrode 208c through the portion 208g, and at the same time, the lower electrode 210a of the piezoelectric element 210 from the wiring 210d through the connecting portion 210f, and the upper electrode 210c from the wiring 210e through the connecting portion 210g. A voltage is applied between them. Then, the piezoelectric element 206 returns to a stopped state, and the structure 220 and the support member 214 directly contact each other above and between the piezoelectric elements 206 and 208, and the piezoelectric element 210 is moved along with the displacement of the piezoelectric body 210b. It curves downward with the support member 214. Further, the bending causes the support member 214 above and between the piezoelectric elements 208 and 210 to be pulled downward, and the structure 220 and the support member 214 are separated from each other at that portion. As a result, the pump chamber 236 is pressurized and the pump chamber 240 has a negative pressure. Therefore, the piezoelectric pump 200 pushes out the fluid in the pump chamber 236, while sucking the fluid into the pump chamber 240, Transfer further downstream. In addition, since the voltage application to the lower electrode 208a is switched from the connection portion 208f to the connection portion 208h, the top portion of the curved piezoelectric element 208 is connected to the connection portion 208f and the connection portion 208g rather than the central portion in the in-plane direction. From the portion slightly approaching the virtual connecting portion at the intermediate point to the portion slightly approaching the virtual connecting portion at the intermediate point between the connecting portion 208h and the connecting portion 208g, that is, downstream in the fluid flow direction. As a result, the fluid is pushed downstream in the pump chamber 238, so that the downstream transfer of the fluid is further promoted.

  Then, in the step (f), the application of voltage between the lower electrode 208a and the upper electrode 208c is stopped, and the lower electrode 210a of the piezoelectric element 210 and the connecting portion from the wiring 210e are connected to the connecting portion 210h from the wiring 210d. A voltage is applied between the upper electrode 210c via 210g and at the same time between the lower electrode 212a of the piezoelectric element 212 from the wiring 212d via the connecting portion 212f and the upper electrode 212c from the wiring 212e via the connecting portion 212g. Apply voltage to Then, the piezoelectric element 208 returns to the stopped state, and the structural body 220 and the support member 214 come into direct contact again above and between the piezoelectric elements 108 and 110, and the piezoelectric element 212 is moved along with the displacement of the piezoelectric body 212b. It curves downward with the support member 214. Also, due to the bending, the support member 214 above and between the piezoelectric elements 210 and 212 is pulled downward, and the protruding portion 224e and the support member 214 are separated from each other at that portion. As a result, the pump chamber 238 is pressurized and the pump chamber 242 has a negative pressure, so that the piezoelectric pump 200 pushes out the fluid in the pump chamber 238 while sucking the fluid into the pump chamber 242 and the second The fluid is discharged from the opening portion 252. In addition, since the voltage application to the lower electrode 210a is switched from the connection part 210f to the connection part 210h, the top of the curved piezoelectric element 210 is connected to the connection part 210f and the connection part 210g rather than the center in the in-plane direction. From the portion slightly approaching the virtual connecting portion at the intermediate point to the portion slightly approaching the virtual connecting portion at the intermediate point between the connecting portion 210h and the connecting portion 210g, that is, downstream in the fluid flow direction. Thereby, since the fluid is pushed downstream in the pump chamber 240, the downstream transfer of the fluid is further promoted.

  By repeating the above steps, the fluid can be transferred via the piezoelectric pump 200 of the present embodiment. In this case, for example, the step (b) may be started together with the start of the step (e). As a result, the amount of fluid transferred per unit time by the piezoelectric pump 200 can be further increased.

  Since the piezoelectric pump 200 of the second embodiment has a similar structure and operates similarly to the piezoelectric pump 170 of the first embodiment, the same effects as the piezoelectric pump 170 can be exhibited. In addition, the piezoelectric pump 200 of the second embodiment can also achieve the following effects. That is, the piezoelectric pump 200 of the present embodiment can move the top of one curved piezoelectric element to the downstream side by arranging the connecting portions between the electrodes and the wiring as described above. As described above, the piezoelectric pump according to the second embodiment not only operates in a swinging manner as a whole of the plurality of piezoelectric elements 202 to 212 but also operates in a swinging manner even when one of the piezoelectric elements is viewed. Transport. Thereby, since the downstream transfer of the fluid is promoted, the applied voltage can be more efficiently converted into the transfer amount of the fluid.

As mentioned above, although the form for implementing this invention was demonstrated, this invention is not limited to the said this embodiment. The present invention can be variously modified without departing from the gist thereof. For example, in another embodiment, the piezoelectric pump may have only one piezoelectric element. FIG. 9 schematically shows an example of such a piezoelectric pump, and shows a state during operation. A piezoelectric pump 900 shown in FIG. 9 includes a structure 920 including one piezoelectric element 902 and one support member 914 that supports the piezoelectric element 902, first and second substrates 922 sandwiching the structure 920, 924, and is formed by being surrounded by the second substrate 924 and the structure 920, and first and second openings 950 and 952 communicating with the pump chamber 930 during operation. It is what you have. The piezoelectric element 902 includes a displacement portion that is displaced by applying a voltage, and a fixed portion that is fixed by being sandwiched between the first and second substrates 922 and 924. Furthermore, the first substrate 922 has a displacement portion such that the displacement portion of the piezoelectric element 902 and the surrounding portion surrounding the outer periphery of the displacement portion of the support member 914 are exposed from the state of being joined to the structure 920. A portion facing the surrounding portion is removed by etching to form an opening 922a. The displacement part, the fixed part, and the surrounding part may have the same structure and arrangement as one of the piezoelectric elements in the second embodiment. The piezoelectric element 902 operates in a swing-like manner like one of the plurality of piezoelectric elements in the second embodiment by arranging the connection portions between the electrodes and the wiring in the same manner as in the second embodiment. Therefore, the fluid can be efficiently transferred. In FIG. 9, the upstream side opening 950 and the pump chamber 930 communicate with each other, while the downstream side opening 952 is closed by the structure 920. In this state, the piezoelectric pump 902 is fluidly connected from the outside. Can be inhaled.
Further, in each of the above embodiments, when the piezoelectric pump is stopped, the structure and the second substrate are in contact with each other and there is almost no space in the pump chamber. In this case, a space may be provided in the pump chamber between the structure and the second substrate. In order to provide such a space, a resin for bonding them between the structure body and the second substrate may be provided with an appropriate thickness, or a further substrate may be provided.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these Examples.

(Effect confirmation test by difference in manufacturing method of first substrate)
In this test, samples as shown in FIGS. 7A and 7B were prepared in order to confirm the amount of displacement of the piezoelectric element in the piezoelectric pump. First, the sample shown in FIG. 7A according to the example is prepared by depositing a lower electrode layer (not shown; material Pt, thickness 0.1 μm) on a 400 μm thick Si substrate by vapor deposition and sputtering. ), A piezoelectric layer (not shown; material PZT, thickness 2 to 2.5 μm), and an upper electrode layer (not shown; material Pt, thickness 0.1 μm) were laminated in this order. Subsequently, the lower electrode layer, the piezoelectric layer, and the upper electrode layer were patterned into a planar shape shown in FIG. 7C by ion milling and etching methods to obtain a piezoelectric element. Next, an insulating polyimide resin as a support member for the piezoelectric element was applied onto the Si substrate and the piezoelectric element, and then the whole was heated at 280 ° C. for 1 hour to cure the polyimide resin.

  Furthermore, the same polyimide resin was apply | coated to the peripheral part of the support member for adhesion | attachment and space formation, and the glass substrate was mounted on it, without heating. Thereafter, the whole was heated at 280 ° C. for 1 hour to cure the adhesive polyimide resin, thereby joining the support member and the glass substrate via the polyimide resin. A part of the Si substrate was etched from the back side by reactive ion etching using Deep-RIE to obtain a sample of the example. Note that the etching of the Si substrate was performed so as to form an opening having a planar shape shown in FIG.

  On the other hand, the preparation of the sample shown in FIG. 7B according to the comparative example is performed by forming a lower electrode layer (not shown; material Pt, thickness 0.1 μm) on a forming Si substrate by vapor deposition and sputtering. The piezoelectric layer (not shown, material PZT, thickness 2 to 2.5 μm) and the upper electrode layer (not shown, material Pt, thickness 0.1 μm) were laminated in this order. Subsequently, the lower electrode layer, the piezoelectric layer, and the upper electrode layer were patterned into a planar shape shown in FIG. 7C by ion milling and etching methods to obtain a piezoelectric element. Next, an insulating polyimide resin as a support member for the piezoelectric element was applied onto the Si substrate and the piezoelectric element, and then the whole was heated at 280 ° C. for 1 hour to cure the polyimide resin.

  Furthermore, the same polyimide resin was apply | coated to the peripheral part of the support member for adhesion | attachment and space formation, and the glass substrate was mounted on it, without heating. Thereafter, the whole was heated at 280 ° C. for 1 hour to cure the adhesive polyimide resin, thereby joining the support member and the glass substrate via the polyimide resin. Then, the entire Si substrate for molding was etched from the back side by etching with hydrofluoric acid. Thereafter, a glass substrate having a planar opening as shown in FIG. 7C is bonded to the surface of the structure of the piezoelectric element and the support member, which is exposed entirely by etching the Si substrate, by film transfer. Thus, a sample of a comparative example was obtained.

  A voltage (driving voltage = 0 to 10 V, driving frequency = 10 Hz) was applied to the piezoelectric element of the obtained sample, and the thickness direction (with the curvature of the structure including the piezoelectric element and the support member at that time ( Maximum) displacement was measured. A laser Doppler vibrometer manufactured by Polytec was used as an evaluation machine. The results are shown in Table 1.

この結果より、実施例に係る試料の方が、比較例に係る試料よりも圧電素子及び支持部材からなる構造体の変位量が大きいことが判明した。

From this result, it was found that the sample according to the example had a larger displacement amount of the structure including the piezoelectric element and the support member than the sample according to the comparative example.

(Effect confirmation test of hard layer)
Next, in order to confirm the effect of the hard layer, the following test was performed. First, in the above “Effect confirmation test by difference in manufacturing method of the first substrate” except that a hard layer (not shown) having various thicknesses is further laminated on the upper electrode layer by a sputtering method. A sample was manufactured in the same manner as the sample manufacturing method shown in FIG. As a sample in this test, a hard layer made of chromium (Cr) or titanium (Ti; Young's modulus = 116 N / m ² ) was prepared.

  A voltage (drive voltage = 0 to 10 V, drive frequency = 10 Hz) is applied to the piezoelectric element of the obtained sample so that the piezoelectric body bends upward (glass substrate side), and to the glass substrate of the structure at that time The contact area was measured by image analysis. The results are shown in FIG.

  From this result, it was found that when chromium is used as the material of the hard layer, the upward deflection decreases as the hard layer becomes thicker, so that the piezoelectric pump can stably transfer the fluid. On the other hand, when titanium is used as the material of the hard layer, the upward deflection does not decrease so much even when the hard layer is thick, so the piezoelectric pump is more stable than when using chromium as the material of the hard layer. It was found that the fluid could not be transferred.

  The piezoelectric pump of the present invention is used for transferring fluids such as liquid reagents used in microchemical reactions, liquids such as inks in high-definition printing apparatuses, gases to be inspected in gas chromatographs, gases such as reaction gases in fuel cells, etc. It can be applied to a device. For example, the piezoelectric pump of the present invention can be provided in a fluid supply device to a gas sensor or a minute filter device.

  DESCRIPTION OF SYMBOLS 102 ... 1st board | substrate, 114 ... Lower electrode, 116 ... Piezoelectric body, 118 ... Upper electrode, 120 ... Piezoelectric element, 122 ... Insulating member, 124 ... Structure, 130a ... 1st opening part, 130b ... 2nd Opening portion, 132 ... second substrate, 170 ... piezoelectric pump.

Claims (4)

A structure including a piezoelectric element and a support member that supports the piezoelectric element;
First and second substrates sandwiching the structure;
Containing
A pump chamber surrounded by the second substrate and the structure;
First and second openings communicating with the pump chamber;
A piezoelectric pump comprising:
The piezoelectric element includes a displacement portion that is displaced by applying a voltage, and a fixed portion that is fixed by being directly or indirectly sandwiched between the first and second substrates.
The first substrate has the displacement portion and the surrounding portion so as to expose the displacement portion and the surrounding portion that surrounds the outer periphery of the displacement portion in the support member from the state of being joined to the structure. Piezoelectric pump in which the part opposite to is removed.   The piezoelectric element includes a first electrode, a piezoelectric body, and a second electrode that are sequentially stacked from the first substrate side, and the first stacked body that includes the first electrode and the piezoelectric body. The piezoelectric pump of claim 1, wherein the piezoelectric pump has a lower Young's modulus and thickness product than the second electrode.   The piezoelectric element further includes a hard layer on the second substrate side of the second electrode, and the first stacked body is a second stacked body including the second electrode and the hard layer. The piezoelectric pump according to claim 2, wherein the piezoelectric pump has a product of low Young's modulus and thickness.   The piezoelectric pump according to claim 3, wherein the hard layer is made of at least one metal selected from the group consisting of chromium, tungsten, tantalum, and platinum.

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