WO2015064216A1 - Piezoelectric sensor - Google Patents

Piezoelectric sensor Download PDF

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Publication number
WO2015064216A1
WO2015064216A1 PCT/JP2014/073620 JP2014073620W WO2015064216A1 WO 2015064216 A1 WO2015064216 A1 WO 2015064216A1 JP 2014073620 W JP2014073620 W JP 2014073620W WO 2015064216 A1 WO2015064216 A1 WO 2015064216A1
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Prior art keywords
piezoelectric
water
layer
piezoelectric sensor
absorbing
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PCT/JP2014/073620
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French (fr)
Japanese (ja)
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靖浩 近藤
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株式会社村田製作所
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Priority to JP2015544854A priority Critical patent/JP5962867B2/en
Publication of WO2015064216A1 publication Critical patent/WO2015064216A1/en

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L1/00—Measuring force or stress, in general
    • G01L1/16—Measuring force or stress, in general using properties of piezoelectric devices
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00—Piezoelectric or electrostrictive devices
    • H10N30/30—Piezoelectric or electrostrictive devices with mechanical input and electrical output, e.g. functioning as generators or sensors
    • H10N30/302—Sensors

Definitions

  • the present invention relates to a piezoelectric sensor.
  • a structure in which a piezoelectric layer is sandwiched between two electrode layers is known.
  • a physical signal such as stress applied to the piezoelectric element is converted into an electrical signal (positive piezoelectric effect) and output from an electrode, or an electrical signal input to the piezoelectric element is physically Is converted into a target signal (inverse piezoelectric effect).
  • piezoelectric elements used for sensors and the like are also required to be small and light.
  • development of a piezoelectric element in which a thin piezoelectric layer is formed on a film-like substrate or a piezoelectric element made of a film material having piezoelectricity has been underway.
  • a piezoelectric sensor using such a piezoelectric element is used for detecting a change in pressure at a part where the piezoelectric sensor is attached and measuring a movement occurring at each part of the living body while being attached to a living body.
  • Application as a sensor is being studied.
  • Examples of the method of attaching the piezoelectric sensor to the living body include a method of bringing the piezoelectric sensor into close contact with the living body using various adhesives or the like (see, for example, Patent Document 1 (Japanese Patent No. 4673363)).
  • Patent Document 1 Japanese Patent No. 4673363
  • the living body part to which the adhesive is in close contact is steamed by moisture such as sweat, causing discomfort to the living body, causing rash on the skin of the part, and facilitating peeling of the piezoelectric sensor.
  • moisture such as sweat
  • Patent Document 2 Japanese Patent Application Laid-Open No. 2011-454944 discloses a hydrocolloid type composition used as an adhesive in a wound dressing to be applied to living skin for treating a wound site.
  • the composition is described as being capable of absorbing water and exudates from wound sites.
  • it is not envisaged to use the composition other than wound dressings such as bandages.
  • An object of the present invention is to provide a piezoelectric sensor that, when used in a state of being attached to a living body, suppresses peeling due to moisture such as sweat and can reduce discomfort and adverse effects on the living body.
  • a piezoelectric element including a piezoelectric film, a signal electrode layer laminated on one main surface of the piezoelectric film, and a ground electrode layer laminated on the other main surface of the piezoelectric film;
  • a piezoelectric sensor comprising: a water-absorbing adhesive layer formed on one main surface side of the piezoelectric element.
  • the water-absorbing pressure-sensitive adhesive layer is composed of a water-absorbing material layer and a moisture-permeable pressure-sensitive adhesive layer laminated on the main surface of the water-absorbing material layer opposite to the piezoelectric element.
  • the present invention it is possible to provide a piezoelectric sensor that suppresses peeling due to moisture such as sweat when used while attached to a living body, and can reduce discomfort and adverse effects on the living body.
  • FIG. 3 is a schematic cross-sectional view for explaining the configuration of the piezoelectric sensor according to the first embodiment.
  • 6 is a schematic cross-sectional view for explaining a configuration of a piezoelectric sensor according to Embodiment 2.
  • FIG. 6 is a schematic cross-sectional view for explaining a configuration of a piezoelectric sensor according to Embodiment 3.
  • the piezoelectric sensor of the present invention includes a piezoelectric element and a water absorbing adhesive layer formed on one main surface side of the piezoelectric element.
  • the “piezoelectric element” includes at least a piezoelectric film, a signal electrode layer laminated on one main surface of the piezoelectric film, and a ground electrode layer laminated on the other main surface of the piezoelectric film.
  • the “piezoelectric film” includes, for example, an insulating film and a piezoelectric layer laminated on one main surface of the insulating film. Further, the “piezoelectric film” may be composed of a film material having piezoelectricity.
  • the piezoelectric film is a thin (film-like) member, and the piezoelectric element including it is preferably thin (film-like).
  • the overall piezoelectric sensor is preferably a thin (film-like) piezoelectric sensor.
  • the insulating film is usually a flexible film, and is preferably a film mainly composed of a polymer having characteristics such as light weight and easy handling.
  • the polymer used as the main component of the insulating film is not particularly limited, and examples thereof include polyimide resins, polyamide resins, polyester resins, and polyolefin resins, preferably heat resistance and dielectric breakdown. It is a polyimide resin excellent in strength and mechanical strength.
  • the constituent material of the piezoelectric layer is not particularly limited as long as it is a substance having piezoelectricity.
  • a compound having a wurtzite structure or a composite oxide having a perovskite structure (ABO 3 ) (perovskite composite) A material whose main component is an oxide) can be used.
  • Examples of the compound having a wurtzite structure include aluminum nitride, gallium nitride, indium nitride, beryllium oxide, zinc oxide, cadmium sulfide, zinc sulfide, or silver iodide.
  • a site of the perovskite structure (ABO 3 ) of the perovskite-based composite oxide for example, at least one element selected from Pb, Ba, Ca, Sr, La, Li, and Bi can be adopted.
  • B site of the perovskite structure (ABO 3 ) for example, at least one element selected from Ti, Zr, Zn, Ni, Mg, Co, W, Nb, Sb, Ta and Fe is adopted. .
  • perovskite-based composite oxides include lead zirconate titanate [Pb (Zr, Ti) O 3 ] (also referred to as PZT) and potassium tantalate niobate [K (Ta, Nb) O 3 ]. , Barium titanate (BaTiO 3 ), (Pb, La) (Zr, Ti) O 3 [lead titanate (PbTiO 3 ), etc.], and the like.
  • a method for forming the piezoelectric layer for example, a sputtering method, a vacuum deposition method, a laser ablation method, an ion plating method, a coating method, a chemical vapor deposition method such as a CVD method, an MOCVD method, and the like are known. Preferred ones can be selected as appropriate.
  • the film thickness of the piezoelectric layer is preferably 0.1 to 100 ⁇ m, more preferably 0.5 to 30 ⁇ m. That is, when the thickness is less than 0.1 ⁇ m, it is difficult to obtain a sufficient output when used for, for example, a sensor or an actuator. On the other hand, when the thickness exceeds 100 ⁇ m, the flexibility is poor and cracking or peeling may occur.
  • the signal electrode layer is a film-like layer composed of electrodes for outputting an electric signal generated in the piezoelectric layer, and is preferably electrically connected to the amplifier. Further, the ground electrode layer is usually not electrically connected to the signal electrode layer but is composed of a grounded conductor.
  • a conductive material composed of a metal such as Al, Ni, Pt, Au, Ag, Ti, Cu or Sn, or an alloy thereof, or a metal oxide for example, a conductive material composed of a metal such as Al, Ni, Pt, Au, Ag, Ti, Cu or Sn, or an alloy thereof, or a metal oxide, A conductive material containing metal nitride can be used.
  • the signal electrode layer and the ground electrode layer are preferably made of a corrosion-resistant metal. Thereby, there is little deterioration in the characteristics of the piezoelectric sensor due to corrosion of the electrodes, and a highly reliable piezoelectric sensor can be obtained.
  • the corrosion-resistant metal include Ti and noble metals (Pt and the like).
  • the formation method of the signal electrode layer and the ground electrode layer is not particularly limited.
  • a physical vapor deposition method such as a coating process, a plating method, a sputtering method, or a vacuum vapor deposition method can be used.
  • the “water-absorbing pressure-sensitive adhesive layer” is a layer that can absorb desired moisture (such as biological sweat) and has desired adhesion even after absorbing moisture.
  • the water absorption capacity of the water-absorbing pressure-sensitive adhesive layer is preferably such that the weight water absorption after 24 hours is 100% or more, more preferably 300% or more.
  • the thickness of the water-absorbing adhesive layer is preferably sufficiently thin so as not to attenuate a pressure signal such as vibration emitted from a living body.
  • the specific thickness of the water-absorbing adhesive layer is preferably 0.6 mm or less, more preferably 0.1 to 0.4 mm.
  • the total thickness of the water-absorbing pressure-sensitive adhesive layer and the piezoelectric element is preferably 1 mm or less, more preferably 0.2 to 0.5 mm.
  • the water-absorbing pressure-sensitive adhesive layer is a two-layered pressure-sensitive adhesive layer composed of a water-absorbing material layer and a pressure-sensitive adhesive layer laminated on the main surface opposite to the piezoelectric element of the water-absorbing material layer.
  • the pressure-sensitive adhesive layer is usually composed of a material having water permeability or is provided with a plurality of through holes.
  • Examples of the material constituting the water absorbing material layer include hydrocolloid and hydrogel.
  • the thickness of the water absorbing material layer is preferably 0.5 mm or less, and more preferably 0.1 to 0.4 mm. When the thickness of the water-absorbing material layer exceeds 0.5 mm, the thickness of the water-absorbing pressure-sensitive adhesive layer is increased, and pressure signals such as vibrations emitted from the living body are easily attenuated. On the other hand, when the thickness of the water absorbing material layer is less than 0.1 mm, it is difficult to obtain sufficient water absorption.
  • Examples of the material constituting the pressure-sensitive adhesive layer include acrylic pressure-sensitive adhesives.
  • the thickness of the pressure-sensitive adhesive layer is preferably 0.1 mm or less, more preferably 0.03 mm or less.
  • water-absorbing pressure-sensitive adhesive layer is a pressure-sensitive adhesive layer having a single-layer structure made of a water-absorbing pressure-sensitive adhesive composition.
  • Examples of the pressure-sensitive adhesive composition having water absorption include a hydrocolloid pressure-sensitive adhesive composition disclosed in Patent Document 2.
  • the piezoelectric sensor of the present invention is used as a sensor for measuring physical signals such as displacement signals and audio signals.
  • the piezoelectric sensor is suitably used as a sensor used in a state where it is attached to a living body.
  • a member having the same configuration as that of the piezoelectric sensor of the present invention can be used as an actuator.
  • FIG. 1 is a schematic cross-sectional view for explaining the configuration of the piezoelectric sensor according to the first embodiment.
  • a piezoelectric element 1 that constitutes a part of the piezoelectric sensor of this embodiment includes a piezoelectric film 11 and two electrode layers 12 and 13 stacked on both main surfaces thereof.
  • the piezoelectric film 11 includes an insulating film and a piezoelectric layer laminated on one main surface of the insulating film.
  • stacked on one main surface of the piezoelectric film 11 becomes a signal electrode layer
  • the electrode layer 12 is electrically connected to the lead wire 41, and the electrode layer 13 is electrically connected to the lead wire 42. However, the signal electrode layer and the ground electrode layer are not electrically connected.
  • the electrode layers 12 and 13 are made of a corrosion-resistant metal (such as titanium or platinum). For this reason, even if the water-absorbing material layer 21 absorbs moisture such as sweat, the electrode layers 12 and 13 (particularly, the electrode layer 13 in contact with the water-absorbing material layer 21) are not easily rusted, and the characteristics of the piezoelectric sensor are hardly deteriorated.
  • a corrosion-resistant metal such as titanium or platinum
  • the piezoelectric sensor of this embodiment includes a water-absorbing adhesive layer 2 on one main surface of the piezoelectric element 1.
  • a cover film 3 made of silicone rubber or PET film is provided on the other main surface of the piezoelectric element 1.
  • the entire piezoelectric element 1 may be covered with a protective member such as a rubber mold.
  • the water-absorbing pressure-sensitive adhesive layer 2 has a two-layer structure composed of a water-absorbing material layer 21 in contact with the piezoelectric element 1 and a pressure-sensitive adhesive layer 22 laminated on the main surface of the water-absorbing material layer 21 opposite to the piezoelectric element 1. It is an adhesive layer.
  • the thickness of the water-absorbing pressure-sensitive adhesive layer 2 (water-absorbing material layer 21) is set to an appropriate thickness (for example, 0.5 mm or less), a physical signal emitted from the skin can be detected with high sensitivity. .
  • the material of the water-absorbing material layer 21 is, for example, a hydrocolloid having a desired water absorption. Since the water-absorbing material layer 21 absorbs moisture such as sweat, the piezoelectric sensor attached to the living body is difficult to peel off, and the living body part to which the piezoelectric sensor is attached becomes difficult to be stuffy.
  • the pressure-sensitive adhesive layer 22 is a moisture-permeable pressure-sensitive adhesive layer. Thereby, moisture such as sweat can be absorbed by the water absorbing material layer 21.
  • a moisture-permeable pressure-sensitive adhesive layer for example, a mesh-shaped pressure-sensitive adhesive layer (a layer containing a porous substrate such as a mesh and a pressure-sensitive adhesive) can be used, and an acrylic pressure-sensitive adhesive is used as the pressure-sensitive adhesive. be able to.
  • the adhesive layer which consists of a gel which has moisture permeability, the adhesive layer which has a some through-hole, etc. can also be used.
  • the adhesive layer 22 is provided with a slit or the like so that the adhesive layer conforms to the unevenness of the skin surface. Is preferred.
  • a release paper (not shown) is usually attached to the surface of the pressure-sensitive adhesive layer 22 (water-absorbing pressure-sensitive adhesive layer 2) opposite to the piezoelectric element 1 so that it can be peeled off.
  • the surface of the water-absorbent pressure-sensitive adhesive layer 2 before use is protected.
  • the piezoelectric sensor of the present embodiment is attached to a living body via the water-absorbing adhesive layer 2 including the water-absorbing material layer 21, it suppresses peeling due to moisture such as sweat when used in a state of being attached to the living body. In addition, it is possible to provide a piezoelectric sensor that can reduce discomfort and adverse effects on the living body.
  • FIG. 2 is a schematic cross-sectional view for explaining the configuration of the piezoelectric sensor of the second embodiment.
  • This embodiment is an amplifier-integrated piezoelectric sensor. That is, as shown in FIG. 2, an amplifier substrate 51 (printed substrate) in which an amplifier 52 is mounted inside a shield case 53 is laminated on the opposite side of the cover film 3 from the piezoelectric element 1.
  • the upper electrode layer 12 (signal electrode layer) of the piezoelectric film is bonded to the input terminal of the amplifier substrate 51 with the conductive adhesive 6.
  • Other points are the same as in the first embodiment.
  • the amplifier 52 has a function of amplifying an electric signal from the signal electrode layer (electrode layer 12), and various known amplifiers (amplifiers) used for electronic circuits can be used.
  • the shield case 53 is not electrically connected to the signal electrode layer and is composed of a grounded conductor. This shield case 53 can prevent electromagnetic noise from being mixed into the amplifier 52.
  • the piezoelectric element 1 and the amplifier 52 are close to each other, it is possible to prevent electromagnetic noise from being mixed into the electric signal before being amplified by the amplifier 52.
  • the piezoelectric sensor is covered with a protective member such as a rubber mold, the amplifier can also be covered with the protective member, so that mixing of electromagnetic noise into the electric signal can be further suppressed.
  • FIG. 3 is a schematic cross-sectional view for explaining the configuration of the piezoelectric sensor according to the third embodiment.
  • the present embodiment is different from the first embodiment in that the piezoelectric film 11 constituting the piezoelectric element 1 and the one electrode layer 13 are bent, but the other embodiments are the same as in the first embodiment. It is the same.
  • the piezoelectric sensor of this embodiment has a structure in which the piezoelectric element 1 is covered with the electrode layer 13, the piezoelectric element is electromagnetically shielded and is less susceptible to electromagnetic noise. The sensitivity of the piezoelectric sensor is improved.
  • Such a piezoelectric element 1 can be manufactured by bending a laminate of the piezoelectric film 11 and the electrode layers 12 and 13.
  • the inner electrode layer 12 is covered with the piezoelectric film 11, a metal having low corrosion resistance can be used as the material of the inner electrode layer 12.
  • the metal material having high corrosion resistance include noble metals such as Ti and Pt, but there is a problem that Ti has low conductivity and the noble metal is expensive, but this embodiment has low corrosion resistance. Since Cu or the like having high conductivity can be selected as an electrode material, the sensitivity of the piezoelectric sensor can be improved, and the manufacturing cost can be reduced.
  • Example 1 a piezoelectric sensor having the same configuration as that of the first embodiment is manufactured, and a signal generated by the piezoelectric sensor when the thickness of the water absorbing material layer 21 is changed to 0.1 mm, 0.5 mm, and 1.5 mm. A test was conducted to examine the change in strength.
  • the piezoelectric element 1 a film obtained by molding aluminum nitride on a PET film was used. As described above, two types of water absorbing material layers having thicknesses of 0.1 mm, 0.5 mm, and 1.5 mm were prepared. As the pressure-sensitive adhesive layer 22, a pressure-sensitive adhesive layer having a thickness of 0.05 mm was formed using an acrylic pressure-sensitive adhesive. As the cover film 3, a polyolefin film was used. These members were stacked, a lead wire 41 was connected to the electrode layer 12, and a lead wire 42 was connected to the electrode layer 13 to produce a piezoelectric sensor.
  • the piezoelectric sensor thus obtained was attached to the skin surface of the human wrist with an adhesive layer, and an electrical signal generated by the piezoelectric element due to the pulse was measured.
  • a signal amplifier (voltage) was measured by connecting a charge amplifier using an operational amplifier.
  • FIGS. 4 to 6 are graphs showing changes in signal intensity during pulse measurement when the thickness of the silicone resin layer (water absorbing material layer) is 0.1 mm, 0.5 mm, and 1.5 mm, respectively. 4 to 6, it can be seen that the thinner the water-absorbing material layer (water-absorbing adhesive layer), the stronger the signal intensity and the higher the sensitivity of the piezoelectric sensor.

Abstract

Provided is a piezoelectric sensor which, when used in a state attached to the body, suppresses peeling due to moisture such as sweat and can moderate unpleasant bodily sensations and reduce adverse effects on the body. This piezoelectric sensor is characterized by being provided with: a piezoelectric element which includes a piezoelectric film, a signal electrode layer laminated on one principal surface of said piezoelectric film, and a ground electrode layer laminated on the other principal surface of said piezoelectric film; and a water absorbent adhesive layer which is formed on one principal surface of the piezoelectric element.

Description

圧電センサPiezoelectric sensor
　本発明は、圧電センサに関する。 The present invention relates to a piezoelectric sensor.
　センサおよびアクチュエータ等に用いられる一般的な圧電素子の構造としては、圧電体層を２つの電極層で挟んだ構造が知られている。圧電素子では、圧電素子に加えられた応力等の物理的信号が電気的信号に変換されて（正圧電効果）、電極から出力されるか、あるいは、圧電素子に入力された電気的信号が物理的信号に変換される（逆圧電効果）。 As a general piezoelectric element structure used for sensors, actuators, etc., a structure in which a piezoelectric layer is sandwiched between two electrode layers is known. In a piezoelectric element, a physical signal such as stress applied to the piezoelectric element is converted into an electrical signal (positive piezoelectric effect) and output from an electrode, or an electrical signal input to the piezoelectric element is physically Is converted into a target signal (inverse piezoelectric effect).
　近年、電子機器の小型化に伴い、センサ等に用いられる圧電素子も小型化、軽量化が求められている。この要求に応えるものとして、フィルム状の基材に薄膜化した圧電体層を形成した圧電素子、または、圧電性をもつフィルム材料による圧電素子の開発が進められている。 In recent years, with the miniaturization of electronic devices, piezoelectric elements used for sensors and the like are also required to be small and light. In response to this demand, development of a piezoelectric element in which a thin piezoelectric layer is formed on a film-like substrate or a piezoelectric element made of a film material having piezoelectricity has been underway.
　さらに、このような圧電素子を用いた圧電センサは、生体に貼り付けた状態で、その圧電センサが貼り付けられた部位の圧力変化を検出し、生体の各部位に生じる動きを測定するためのセンサとして、応用することが検討されている。 Furthermore, a piezoelectric sensor using such a piezoelectric element is used for detecting a change in pressure at a part where the piezoelectric sensor is attached and measuring a movement occurring at each part of the living body while being attached to a living body. Application as a sensor is being studied.
　圧電センサを生体に貼り付ける方法としては、種々の粘着剤等を用いて圧電センサを生体に密着させる方法が挙げられる（例えば、特許文献１（特許第４６７４３６３号公報）参照）が、この場合、粘着剤が密着した生体部位が汗等の水分により蒸れた状態となり、生体に不快感が生じると共に、該部位の皮膚にかぶれ等が生じたり、圧電センサが剥がれやすくなったりするという問題がある。通常、圧電センサを貼り付けた状態は長時間続く場合が多いため、これらの問題は、実用面において重要な問題である。 Examples of the method of attaching the piezoelectric sensor to the living body include a method of bringing the piezoelectric sensor into close contact with the living body using various adhesives or the like (see, for example, Patent Document 1 (Japanese Patent No. 4673363)). There is a problem in that the living body part to which the adhesive is in close contact is steamed by moisture such as sweat, causing discomfort to the living body, causing rash on the skin of the part, and facilitating peeling of the piezoelectric sensor. Usually, since the state in which the piezoelectric sensor is attached often lasts for a long time, these problems are important problems in practical use.
　なお、特許文献２（特開２０１１－４５４９４号公報）には、創傷部位を治療するために生体の皮膚に貼り付けられる創傷被覆材において、粘着剤として用いられるハイドロコロイド型組成物が開示され、この組成物は、水や創傷部位からの浸出液を吸収できる旨記載されている。しかし、該組成物を絆創膏等の創傷被覆材以外に用いることは想定されていない。 Patent Document 2 (Japanese Patent Application Laid-Open No. 2011-45494) discloses a hydrocolloid type composition used as an adhesive in a wound dressing to be applied to living skin for treating a wound site. The composition is described as being capable of absorbing water and exudates from wound sites. However, it is not envisaged to use the composition other than wound dressings such as bandages.
特許第４６７４３６３号公報Japanese Patent No. 4673363 特開２０１１－４５４９４号公報JP 2011-45494 A
　本発明は、生体に貼り付けた状態で使用する場合に、汗などの水分による剥がれを抑制し、生体に生じる不快感や生体への悪影響を低減できる圧電センサを提供することを目的とする。 An object of the present invention is to provide a piezoelectric sensor that, when used in a state of being attached to a living body, suppresses peeling due to moisture such as sweat and can reduce discomfort and adverse effects on the living body.
　［１］　圧電フィルム、前記圧電フィルムの一方の主面に積層された信号電極層、および、前記圧電フィルムの他方の主面に積層された接地電極層を含む圧電素子と、
　前記圧電素子の一方の主面側に形成された吸水性粘着層とを備えることを特徴とする、圧電センサ。 [1] A piezoelectric element including a piezoelectric film, a signal electrode layer laminated on one main surface of the piezoelectric film, and a ground electrode layer laminated on the other main surface of the piezoelectric film;
A piezoelectric sensor comprising: a water-absorbing adhesive layer formed on one main surface side of the piezoelectric element.
　［２］　前記吸水性粘着層は、吸水材層と、該吸水材層の前記圧電素子と反対側の主面に積層された透湿性を有する粘着剤層とから構成される、上記［１］に記載の圧電センサ。 [2] The water-absorbing pressure-sensitive adhesive layer is composed of a water-absorbing material layer and a moisture-permeable pressure-sensitive adhesive layer laminated on the main surface of the water-absorbing material layer opposite to the piezoelectric element. The piezoelectric sensor described in 1.
　［３］　前記吸水性粘着層は、吸水性を有する粘着剤組成物からなる単層である、上記［１］に記載の圧電センサ。 [3] The piezoelectric sensor according to [1], wherein the water-absorbing pressure-sensitive adhesive layer is a single layer made of a water-absorbing pressure-sensitive adhesive composition.
　［４］　前記信号電極層および前記接地電極層は、耐腐食性の金属からなる、上記［１］～［３］のいずれかに記載の圧電センサ。 [4] The piezoelectric sensor according to any one of [1] to [3], wherein the signal electrode layer and the ground electrode layer are made of a corrosion-resistant metal.
　［５］　前記吸水性粘着層の厚さが０．６ｍｍ以下である、上記［１］～［４］のいずれかに記載の圧電センサ。 [5] The piezoelectric sensor according to any one of [1] to [4], wherein the water-absorbing adhesive layer has a thickness of 0.6 mm or less.
　［６］　前記吸水材層の厚さが０．５ｍｍ以下である、上記［２］に記載の圧電センサ。 [6] The piezoelectric sensor according to [2], wherein the thickness of the water absorbing material layer is 0.5 mm or less.
　［７］　生体に貼り付けた状態で使用される、上記［１］～［６］のいずれかに記載の圧電センサ。 [7] The piezoelectric sensor according to any one of [1] to [6], which is used in a state of being attached to a living body.
　本発明によれば、生体に貼り付けた状態で使用する場合に、汗などの水分による剥がれを抑制し、生体に生じる不快感や生体への悪影響を低減できる圧電センサを提供することができる。 According to the present invention, it is possible to provide a piezoelectric sensor that suppresses peeling due to moisture such as sweat when used while attached to a living body, and can reduce discomfort and adverse effects on the living body.
実施形態１の圧電センサの構成を説明するための断面模式図である。FIG. 3 is a schematic cross-sectional view for explaining the configuration of the piezoelectric sensor according to the first embodiment. 実施形態２の圧電センサの構成を説明するための断面模式図である。6 is a schematic cross-sectional view for explaining a configuration of a piezoelectric sensor according to Embodiment 2. FIG. 実施形態３の圧電センサの構成を説明するための断面模式図である。6 is a schematic cross-sectional view for explaining a configuration of a piezoelectric sensor according to Embodiment 3. FIG. 実施例１で、シリコーン樹脂層と吸水性粘着槽の合計の厚さが０．１ｍｍの場合における脈拍測定時の信号強度の変化を示すグラフである。In Example 1, it is a graph which shows the change of the signal strength at the time of a pulse measurement in case the total thickness of a silicone resin layer and a water absorbing adhesive tank is 0.1 mm. 実施例１で、シリコーン樹脂層と吸水性粘着槽の合計の厚さが０．５ｍｍの場合における脈拍測定時の信号強度の変化を示すグラフである。In Example 1, it is a graph which shows the change of the signal strength at the time of a pulse measurement in case the total thickness of a silicone resin layer and a water absorbing adhesive tank is 0.5 mm. 実施例１で、シリコーン樹脂層と吸水性粘着槽の合計の厚さが１．５ｍｍの場合における脈拍測定時の信号強度の変化を示すグラフである。In Example 1, it is a graph which shows the change of the signal strength at the time of a pulse measurement in case the total thickness of a silicone resin layer and a water absorbing adhesive tank is 1.5 mm.
　本発明の圧電センサは、圧電素子と、圧電素子の一方の主面側に形成された吸水性粘着層とを備える。 The piezoelectric sensor of the present invention includes a piezoelectric element and a water absorbing adhesive layer formed on one main surface side of the piezoelectric element.
　（圧電素子）
　「圧電素子」は、少なくとも、圧電フィルム、圧電フィルムの一方の主面に積層された信号電極層、および、圧電フィルムの他方の主面に積層された接地電極層を含む。「圧電フィルム」は、例えば、絶縁性フィルム、および、該絶縁性フィルムの一方の主面に積層された圧電体層から構成される。また、「圧電体フィルム」は、圧電性を有するフィルム素材によって構成されるものであってもよい。 (Piezoelectric element)
The “piezoelectric element” includes at least a piezoelectric film, a signal electrode layer laminated on one main surface of the piezoelectric film, and a ground electrode layer laminated on the other main surface of the piezoelectric film. The “piezoelectric film” includes, for example, an insulating film and a piezoelectric layer laminated on one main surface of the insulating film. Further, the “piezoelectric film” may be composed of a film material having piezoelectricity.
　圧電フィルムは薄型（フィルム状）の部材であり、それを含む圧電素子も薄型（フィルム状）であることが好ましい。圧電センサ全体としても、薄型（フィルム状）の圧電センサであることがより好ましい。 The piezoelectric film is a thin (film-like) member, and the piezoelectric element including it is preferably thin (film-like). The overall piezoelectric sensor is preferably a thin (film-like) piezoelectric sensor.
　絶縁性フィルムは、通常は可撓性を有するフィルムであり、軽量で、取り扱い易いといった特徴を有する高分子を主成分とするフィルムであることが好ましい。絶縁性フィルムの主成分として用いられる高分子は、特に限定されるものではないが、例えば、ポリイミド系樹脂、ポリアミド系樹脂、ポリエステル系樹脂、ポリオレフィン系樹脂であり、好ましくは、耐熱性、絶縁破壊強度、機械的強度に優れるポリイミド系樹脂である。 The insulating film is usually a flexible film, and is preferably a film mainly composed of a polymer having characteristics such as light weight and easy handling. The polymer used as the main component of the insulating film is not particularly limited, and examples thereof include polyimide resins, polyamide resins, polyester resins, and polyolefin resins, preferably heat resistance and dielectric breakdown. It is a polyimide resin excellent in strength and mechanical strength.
　圧電体層の構成材料は、圧電性を有する物質であれば特に限定されるものではないが、例えば、ウルツ鉱型構造を有する化合物やペロブスカイト構造（ＡＢＯ３）を有する複合酸化物（ペロブスカイト系複合酸化物）を主成分とする材料を用いることができる。 The constituent material of the piezoelectric layer is not particularly limited as long as it is a substance having piezoelectricity. For example, a compound having a wurtzite structure or a composite oxide having a perovskite structure (ABO 3 ) (perovskite composite) A material whose main component is an oxide) can be used.
　ウルツ鉱型構造を有する化合物としては、例えば、窒化アルミニウム、窒化ガリウム、窒化インジウム、酸化ベリリウム、酸化亜鉛、硫化カドミウム、硫化亜鉛またはヨウ化銀が挙げられる。 Examples of the compound having a wurtzite structure include aluminum nitride, gallium nitride, indium nitride, beryllium oxide, zinc oxide, cadmium sulfide, zinc sulfide, or silver iodide.
　ペロブスカイト系複合酸化物のペロブスカイト構造（ＡＢＯ３）のＡサイトとしては、例えば、Ｐｂ，Ｂａ，Ｃａ，Ｓｒ，Ｌａ，ＬｉおよびＢｉの中から選択される少なくとも１種の元素を採用することができる。ペロブスカイト構造（ＡＢＯ３）のＢサイトとしては、例えば、Ｔｉ，Ｚｒ，Ｚｎ，Ｎｉ，Ｍｇ，Ｃｏ，Ｗ，Ｎｂ，Ｓｂ，ＴａおよびＦｅの中から選択される少なくとも１種の元素が採用される。 As the A site of the perovskite structure (ABO 3 ) of the perovskite-based composite oxide, for example, at least one element selected from Pb, Ba, Ca, Sr, La, Li, and Bi can be adopted. . As the B site of the perovskite structure (ABO 3 ), for example, at least one element selected from Ti, Zr, Zn, Ni, Mg, Co, W, Nb, Sb, Ta and Fe is adopted. .
　このようなペロブスカイト系複合酸化物の具体例としては、チタン酸ジルコン酸鉛［Ｐｂ（Ｚｒ，Ｔｉ）Ｏ３］（ＰＺＴともいう）、ニオブ酸タンタル酸カリウム［Ｋ（Ｔａ，Ｎｂ）Ｏ３］、チタン酸バリウム（ＢａＴｉＯ３）、（Ｐｂ，Ｌａ）（Ｚｒ，Ｔｉ）Ｏ３［チタン酸鉛（ＰｂＴｉＯ３）など］、等が挙げられる。 Specific examples of such perovskite-based composite oxides include lead zirconate titanate [Pb (Zr, Ti) O 3 ] (also referred to as PZT) and potassium tantalate niobate [K (Ta, Nb) O 3 ]. , Barium titanate (BaTiO 3 ), (Pb, La) (Zr, Ti) O 3 [lead titanate (PbTiO 3 ), etc.], and the like.
　圧電体層の形成方法としては、例えば、スパッタリング法、真空蒸着法、レーザーアブレーション法、イオンプレーティング法、コーティング法や、ＣＶＤ法、ＭＯＣＶＤ法等の化学蒸着法が知られており、その中から好ましいものを適宜選択することができる。 As a method for forming the piezoelectric layer, for example, a sputtering method, a vacuum deposition method, a laser ablation method, an ion plating method, a coating method, a chemical vapor deposition method such as a CVD method, an MOCVD method, and the like are known. Preferred ones can be selected as appropriate.
　圧電体層の膜厚は、好ましくは０．１～１００μｍであり、より好ましくは０．５～３０μｍである。すなわち、厚みが０．１μｍ未満では、例えばセンサやアクチュエータ等に用いた場合に十分な出力が得られにくく、逆に１００μｍを超えると柔軟性が乏しくなりクラックや剥離を引き起こす恐れがある。 The film thickness of the piezoelectric layer is preferably 0.1 to 100 μm, more preferably 0.5 to 30 μm. That is, when the thickness is less than 0.1 μm, it is difficult to obtain a sufficient output when used for, for example, a sensor or an actuator. On the other hand, when the thickness exceeds 100 μm, the flexibility is poor and cracking or peeling may occur.
　信号電極層は、圧電体層で発生した電気信号を出力するための電極からなる膜状の層であり、アンプに電気的に接続されることが好ましい。また、接地電極層は、通常、信号電極層と電気的に接続されておらず、接地された導体から構成される。 The signal electrode layer is a film-like layer composed of electrodes for outputting an electric signal generated in the piezoelectric layer, and is preferably electrically connected to the amplifier. Further, the ground electrode layer is usually not electrically connected to the signal electrode layer but is composed of a grounded conductor.
　信号電極層および接地電極層の材料としては、例えば、Ａｌ、Ｎｉ、Ｐｔ、Ａｕ、Ａｇ、Ｔｉ、ＣｕまたはＳｎ等の金属やこれらの合金から構成される導電性材料、または、金属酸化物や金属窒化物を含む導電性材料を用いることができる。 As the material of the signal electrode layer and the ground electrode layer, for example, a conductive material composed of a metal such as Al, Ni, Pt, Au, Ag, Ti, Cu or Sn, or an alloy thereof, or a metal oxide, A conductive material containing metal nitride can be used.
　信号電極層および接地電極層は、耐腐食性の金属からなることが好ましい。これにより、電極の腐食による圧電センサの特性劣化が少なく、信頼性の高い圧電センサを得ることができる。耐腐食性の金属としては、例えば、Ｔｉや貴金属（Ｐｔなど）が挙げられる。 The signal electrode layer and the ground electrode layer are preferably made of a corrosion-resistant metal. Thereby, there is little deterioration in the characteristics of the piezoelectric sensor due to corrosion of the electrodes, and a highly reliable piezoelectric sensor can be obtained. Examples of the corrosion-resistant metal include Ti and noble metals (Pt and the like).
　信号電極層および接地電極層の形成方法としては、特に限定されないが、例えば、塗布処理、メッキ法またはスパッタリング法や、真空蒸着法等の物理蒸着法を用いることができる。なお、接地電極層は、他にも、例えば、上記材料からなる薄膜を積層することで形成してもよい。 The formation method of the signal electrode layer and the ground electrode layer is not particularly limited. For example, a physical vapor deposition method such as a coating process, a plating method, a sputtering method, or a vacuum vapor deposition method can be used. In addition, you may form a ground electrode layer by laminating | stacking the thin film which consists of said material, for example.
　（吸水性粘着層）
　「吸水性粘着層」は、所望の水分（生体の汗など）を吸収することができ、水分を吸収した後においても所望の粘着性を有する層である。吸水性粘着層の吸水能力は、好ましくは２４時間後の重量吸水率が１００％以上であり、より好ましくは３００％以上である。 (Water-absorbing adhesive layer)
The “water-absorbing pressure-sensitive adhesive layer” is a layer that can absorb desired moisture (such as biological sweat) and has desired adhesion even after absorbing moisture. The water absorption capacity of the water-absorbing pressure-sensitive adhesive layer is preferably such that the weight water absorption after 24 hours is 100% or more, more preferably 300% or more.
　吸水性粘着層の厚さは、生体から発せられる振動等の圧力信号を減衰しないように、十分に薄いことが好ましい。具体的な吸水性粘着層の厚さは、好ましくは０．６ｍｍ以下であり、より好ましくは０．１～０．４ｍｍである。なお、吸水性粘着層および圧電素子の厚さの合計は、好ましくは１ｍｍ以下であり、より好ましくは０．２～０．５ｍｍである。 The thickness of the water-absorbing adhesive layer is preferably sufficiently thin so as not to attenuate a pressure signal such as vibration emitted from a living body. The specific thickness of the water-absorbing adhesive layer is preferably 0.6 mm or less, more preferably 0.1 to 0.4 mm. The total thickness of the water-absorbing pressure-sensitive adhesive layer and the piezoelectric element is preferably 1 mm or less, more preferably 0.2 to 0.5 mm.
　吸水性粘着層の一例としては、吸水材層と、該吸水材層の圧電素子と反対側の主面に積層された粘着剤層とから構成される２層構造の粘着層が挙げられる。この場合において、通常、粘着剤層は、透水性を有する材料から構成されるか、または、複数の貫通孔が設けられている。 An example of the water-absorbing pressure-sensitive adhesive layer is a two-layered pressure-sensitive adhesive layer composed of a water-absorbing material layer and a pressure-sensitive adhesive layer laminated on the main surface opposite to the piezoelectric element of the water-absorbing material layer. In this case, the pressure-sensitive adhesive layer is usually composed of a material having water permeability or is provided with a plurality of through holes.
　吸水材層を構成する材料としては、例えば、ハイドロコロイド、ハイドロゲルが挙げられる。吸水材層の厚さは、好ましくは０．５ｍｍ以下であり、より好ましくは０．１～０．４ｍｍである。吸水材層の厚さが０．５ｍｍを超える場合、吸水性粘着層の厚さが厚くなり、生体から発せられる振動等の圧力信号が減衰されやすくなる。一方、吸水材層の厚さが０．１ｍｍ未満の場合は、十分な吸水性が得られにくい。 Examples of the material constituting the water absorbing material layer include hydrocolloid and hydrogel. The thickness of the water absorbing material layer is preferably 0.5 mm or less, and more preferably 0.1 to 0.4 mm. When the thickness of the water-absorbing material layer exceeds 0.5 mm, the thickness of the water-absorbing pressure-sensitive adhesive layer is increased, and pressure signals such as vibrations emitted from the living body are easily attenuated. On the other hand, when the thickness of the water absorbing material layer is less than 0.1 mm, it is difficult to obtain sufficient water absorption.
　粘着剤層を構成する材料としては、例えば、アクリル系粘着剤が挙げられる。粘着剤層の厚さは、好ましくは０．１ｍｍ以下であり、より好ましくは０．０３ｍｍ以下である。 Examples of the material constituting the pressure-sensitive adhesive layer include acrylic pressure-sensitive adhesives. The thickness of the pressure-sensitive adhesive layer is preferably 0.1 mm or less, more preferably 0.03 mm or less.
　吸水性粘着層の他の例としては、吸水性を有する粘着剤組成物からなる単層構造の粘着剤層が挙げられる。吸水性を有する粘着剤組成物としては、例えば、特許文献２に開示されるハイドロコロイド型粘着剤組成物が挙げられる。 Another example of the water-absorbing pressure-sensitive adhesive layer is a pressure-sensitive adhesive layer having a single-layer structure made of a water-absorbing pressure-sensitive adhesive composition. Examples of the pressure-sensitive adhesive composition having water absorption include a hydrocolloid pressure-sensitive adhesive composition disclosed in Patent Document 2.
　本発明の圧電センサは、例えば、変位信号、音声信号などの物理信号を計測するためのセンサとして用いられる。圧電センサは、特に、生体に貼り付けられた状態で使用されるセンサとして好適に用いられる。なお、本発明の圧電センサと同様の構成を有する部材をアクチュエータとして用いることもできる。 The piezoelectric sensor of the present invention is used as a sensor for measuring physical signals such as displacement signals and audio signals. In particular, the piezoelectric sensor is suitably used as a sensor used in a state where it is attached to a living body. A member having the same configuration as that of the piezoelectric sensor of the present invention can be used as an actuator.
　以下、本発明の圧電素子の実施形態について、図面を参照して説明する。なお、図面において、同一の参照符号は、同一部分または相当部分を表すものである。また、長さ、幅、厚さ、深さなどの寸法関係は図面の明瞭化と簡略化のために適宜変更されており、実際の寸法関係を表すものではない。 Hereinafter, embodiments of the piezoelectric element of the present invention will be described with reference to the drawings. In the drawings, the same reference numerals represent the same or corresponding parts. In addition, dimensional relationships such as length, width, thickness, and depth are changed as appropriate for clarity and simplification of the drawings, and do not represent actual dimensional relationships.
　（実施形態１）
　図１は、実施形態１の圧電センサの構成を説明するための断面模式図である。図１を参照して、本実施形態の圧電センサの一部を構成する圧電素子１は、圧電フィルム１１と、その両主面に積層された２つの電極層１２，１３とから構成される。圧電フィルム１１は、絶縁性フィルム、および、絶縁性フィルムの一方の主面に積層された圧電体層から構成されている。なお、圧電フィルム１１の一方の主面に積層される電極層１２が信号電極層となり、圧電フィルム１１の他方の面に積層される電極層１３が接地電極層となる。電極層１２は、引き出し配線４１に、電極層１３は引き出し配線４２に電気的に接続されている。ただし、信号電極層と接地電極層とは電気的に接続されていない。 (Embodiment 1)
FIG. 1 is a schematic cross-sectional view for explaining the configuration of the piezoelectric sensor according to the first embodiment. Referring to FIG. 1, a piezoelectric element 1 that constitutes a part of the piezoelectric sensor of this embodiment includes a piezoelectric film 11 and two electrode layers 12 and 13 stacked on both main surfaces thereof. The piezoelectric film 11 includes an insulating film and a piezoelectric layer laminated on one main surface of the insulating film. In addition, the electrode layer 12 laminated | stacked on one main surface of the piezoelectric film 11 becomes a signal electrode layer, and the electrode layer 13 laminated | stacked on the other surface of the piezoelectric film 11 becomes a ground electrode layer. The electrode layer 12 is electrically connected to the lead wire 41, and the electrode layer 13 is electrically connected to the lead wire 42. However, the signal electrode layer and the ground electrode layer are not electrically connected.
　電極層１２，１３（信号電極層および接地電極層）は、耐腐食性の金属（チタンや白金など）から構成されている。このため、吸水材層２１が汗などの水分を吸収しても電極層１２，１３（特に、吸水材層２１と接している電極層１３）が錆び難く、圧電センサの特性が劣化し難い。 The electrode layers 12 and 13 (signal electrode layer and ground electrode layer) are made of a corrosion-resistant metal (such as titanium or platinum). For this reason, even if the water-absorbing material layer 21 absorbs moisture such as sweat, the electrode layers 12 and 13 (particularly, the electrode layer 13 in contact with the water-absorbing material layer 21) are not easily rusted, and the characteristics of the piezoelectric sensor are hardly deteriorated.
　本実施形態の圧電センサは、圧電素子１の一方の主面上に吸水性粘着層２を備えている。なお、圧電素子１の他方の主面上には、シリコーンゴムやＰＥＴフィルムなどから構成されるカバーフィルム３を備えている。なお、このようなカバーフィルムを設ける代わりに、例えば、圧電素子１全体をゴムモールド等の保護部材で被覆してもよい。 The piezoelectric sensor of this embodiment includes a water-absorbing adhesive layer 2 on one main surface of the piezoelectric element 1. A cover film 3 made of silicone rubber or PET film is provided on the other main surface of the piezoelectric element 1. Instead of providing such a cover film, for example, the entire piezoelectric element 1 may be covered with a protective member such as a rubber mold.
　吸水性粘着層２は、圧電素子１に接した吸水材層２１と、吸水材層２１の圧電素子１と反対側の主面に積層された粘着剤層２２とから構成される２層構造の粘着層である。ここで、吸水性粘着層２（吸水材層２１）の厚さを適切な薄さ（例えば、０．５ｍｍ以下）にしているため、皮膚が発した物理的信号を感度良く検出することができる。 The water-absorbing pressure-sensitive adhesive layer 2 has a two-layer structure composed of a water-absorbing material layer 21 in contact with the piezoelectric element 1 and a pressure-sensitive adhesive layer 22 laminated on the main surface of the water-absorbing material layer 21 opposite to the piezoelectric element 1. It is an adhesive layer. Here, since the thickness of the water-absorbing pressure-sensitive adhesive layer 2 (water-absorbing material layer 21) is set to an appropriate thickness (for example, 0.5 mm or less), a physical signal emitted from the skin can be detected with high sensitivity. .
　吸水材層２１の材質は、例えば、所望の吸水性を有するハイドロコロイドである。吸水材層２１が汗などの水分を吸収するため、生体に貼り付けた圧電センサが剥れにくく、圧電センサを貼り付けた生体部位が蒸れにくくなる。 The material of the water-absorbing material layer 21 is, for example, a hydrocolloid having a desired water absorption. Since the water-absorbing material layer 21 absorbs moisture such as sweat, the piezoelectric sensor attached to the living body is difficult to peel off, and the living body part to which the piezoelectric sensor is attached becomes difficult to be stuffy.
　粘着剤層２２は、透湿性を有する粘着剤層である。これにより、汗などの水分を吸水材層２１で吸収することが可能となる。透湿性を有する粘着剤層としては、例えば、メッシュ状の粘着剤層（メッシュ等の多孔性基材と粘着剤を含む層）を用いることができ、粘着剤としてはアクリル系の粘着剤を用いることができる。また、透湿性を有するゲルからなる粘着剤層や、複数の貫通孔を有する粘着剤層などを用いることもできる。 The pressure-sensitive adhesive layer 22 is a moisture-permeable pressure-sensitive adhesive layer. Thereby, moisture such as sweat can be absorbed by the water absorbing material layer 21. As the moisture-permeable pressure-sensitive adhesive layer, for example, a mesh-shaped pressure-sensitive adhesive layer (a layer containing a porous substrate such as a mesh and a pressure-sensitive adhesive) can be used, and an acrylic pressure-sensitive adhesive is used as the pressure-sensitive adhesive. be able to. Moreover, the adhesive layer which consists of a gel which has moisture permeability, the adhesive layer which has a some through-hole, etc. can also be used.
　なお、例えば、人体の喉頭***の皮膚表面に圧電センサを貼り付けるような場合は、粘着剤層２２にスリット等を設けることで、粘着剤層が皮膚の表面の凹凸に適合するようにすることが好ましい。 For example, when a piezoelectric sensor is attached to the surface of the human laryngeal protuberance, the adhesive layer 22 is provided with a slit or the like so that the adhesive layer conforms to the unevenness of the skin surface. Is preferred.
　なお、使用前の圧電センサにおいて、粘着剤層２２（吸水性粘着層２）の圧電素子１と反対側の表面には、通常、剥離紙（図示せず）が剥離可能なように貼り付けられおり、使用前の吸水性粘着層２の表面を保護している。 In the piezoelectric sensor before use, a release paper (not shown) is usually attached to the surface of the pressure-sensitive adhesive layer 22 (water-absorbing pressure-sensitive adhesive layer 2) opposite to the piezoelectric element 1 so that it can be peeled off. The surface of the water-absorbent pressure-sensitive adhesive layer 2 before use is protected.
　本実施形態の圧電センサは、吸水材層２１を含む吸水性粘着層２を介して生体に貼り付けられるため、生体に貼り付けた状態で使用する場合に、汗などの水分による剥がれを抑制し、生体に生じる不快感や生体への悪影響を低減できる圧電センサを提供することができる。 Since the piezoelectric sensor of the present embodiment is attached to a living body via the water-absorbing adhesive layer 2 including the water-absorbing material layer 21, it suppresses peeling due to moisture such as sweat when used in a state of being attached to the living body. In addition, it is possible to provide a piezoelectric sensor that can reduce discomfort and adverse effects on the living body.
　（実施形態２）
　図２は、実施形態２の圧電センサの構成を説明するための断面模式図である。本実施形態は、アンプ一体型の圧電センサである。すなわち、図２に示されるように、シールドケース５３の内部にアンプ５２が搭載されたアンプ基板５１（プリント基板）が、カバーフィルム３の圧電素子１と反対側に積層されている。圧電フィルムの上側の電極層１２（信号電極層）は、アンプ基板５１の入力端子に導電性接着剤６で接合されている。その他の点は、実施形態１と同様である。 (Embodiment 2)
FIG. 2 is a schematic cross-sectional view for explaining the configuration of the piezoelectric sensor of the second embodiment. This embodiment is an amplifier-integrated piezoelectric sensor. That is, as shown in FIG. 2, an amplifier substrate 51 (printed substrate) in which an amplifier 52 is mounted inside a shield case 53 is laminated on the opposite side of the cover film 3 from the piezoelectric element 1. The upper electrode layer 12 (signal electrode layer) of the piezoelectric film is bonded to the input terminal of the amplifier substrate 51 with the conductive adhesive 6. Other points are the same as in the first embodiment.
　アンプ５２は、信号電極層（電極層１２）からの電気信号を増幅する機能を有しており、電子回路に用いられる種々公知のアンプ（増幅器）を用いることができる。シールドケース５３は、信号電極層と電気的に接続されておらず、接地された導体から構成される。このシールドケース５３により、アンプ５２に電磁ノイズが混入することを抑制できる。また、圧電素子１とアンプ５２が近接しているため、アンプ５２で増幅される前の電気信号に、電磁ノイズが混入することを抑制できる。なお、ゴムモールドなどの保護部材で圧電センサを被覆する場合は、アンプも保護部材で被覆することで、電気信号への電磁ノイズの混入をさらに抑制することができる。 The amplifier 52 has a function of amplifying an electric signal from the signal electrode layer (electrode layer 12), and various known amplifiers (amplifiers) used for electronic circuits can be used. The shield case 53 is not electrically connected to the signal electrode layer and is composed of a grounded conductor. This shield case 53 can prevent electromagnetic noise from being mixed into the amplifier 52. Moreover, since the piezoelectric element 1 and the amplifier 52 are close to each other, it is possible to prevent electromagnetic noise from being mixed into the electric signal before being amplified by the amplifier 52. When the piezoelectric sensor is covered with a protective member such as a rubber mold, the amplifier can also be covered with the protective member, so that mixing of electromagnetic noise into the electric signal can be further suppressed.
　また、使用時に、アンプも吸水性粘着層で生体に貼り付けて支持されることになるため、アンプと圧電素子の電極層との接合部にかかるストレス（外部応力）が緩和され、該接合部における断線等を抑制することができる。 In addition, since the amplifier is also attached to and supported by the living body with the water-absorbing adhesive layer during use, stress (external stress) applied to the joint portion between the amplifier and the electrode layer of the piezoelectric element is relieved. Disconnection or the like can be suppressed.
　（実施形態３）
　図３は、実施形態３の圧電センサの構成を説明するための断面模式図である。本実施形態では、図３に示されるように、圧電素子１を構成する圧電フィルム１１および一方の電極層１３が折り曲げられた形状である点で実施形態１と異なるが、それ以外は実施形態１と同様である。 (Embodiment 3)
FIG. 3 is a schematic cross-sectional view for explaining the configuration of the piezoelectric sensor according to the third embodiment. As shown in FIG. 3, the present embodiment is different from the first embodiment in that the piezoelectric film 11 constituting the piezoelectric element 1 and the one electrode layer 13 are bent, but the other embodiments are the same as in the first embodiment. It is the same.
　このように、本実施形態の圧電センサは、圧電素子１が電極層１３に覆われた構造を有しているため、圧電素子が電磁的にシールドされ、電磁ノイズの影響を受けにくくなるため、圧電センサの感度が向上する。なお、このような圧電素子１は、圧電フィルム１１と電極層１２，１３の積層体を折り曲げることにより、製造することができる。 Thus, since the piezoelectric sensor of this embodiment has a structure in which the piezoelectric element 1 is covered with the electrode layer 13, the piezoelectric element is electromagnetically shielded and is less susceptible to electromagnetic noise. The sensitivity of the piezoelectric sensor is improved. Such a piezoelectric element 1 can be manufactured by bending a laminate of the piezoelectric film 11 and the electrode layers 12 and 13.
　また、内側の電極層１２が圧電フィルム１１で覆われているため、内側の電極層１２の材料として、耐腐食性の低い金属を用いることもできる。耐腐食性の高い金属材料としては、ＴｉやＰｔ等の貴金属が挙げられるが、Ｔｉは導電率が低く、貴金属は高価であるという問題があるが、本実施形態は、耐腐食性は低いものの導電率が高く安価なＣｕ等を電極材料として選択することができるため、圧電センサの感度を向上させることができ、製造コストを低減することができる。 Further, since the inner electrode layer 12 is covered with the piezoelectric film 11, a metal having low corrosion resistance can be used as the material of the inner electrode layer 12. Examples of the metal material having high corrosion resistance include noble metals such as Ti and Pt, but there is a problem that Ti has low conductivity and the noble metal is expensive, but this embodiment has low corrosion resistance. Since Cu or the like having high conductivity can be selected as an electrode material, the sensitivity of the piezoelectric sensor can be improved, and the manufacturing cost can be reduced.
　（実施例１）
　本実施例では、実施形態１と同様の構成を有する圧電センサを作製し、吸水材層２１の厚さを０．１ｍｍ、０．５ｍｍおよび１．５ｍｍと変化させたときの圧電センサで生じる信号強度の変化を調べる試験を行った。 Example 1
In this example, a piezoelectric sensor having the same configuration as that of the first embodiment is manufactured, and a signal generated by the piezoelectric sensor when the thickness of the water absorbing material layer 21 is changed to 0.1 mm, 0.5 mm, and 1.5 mm. A test was conducted to examine the change in strength.
　圧電素子１としては、ＰＥＴフィルム上に窒化アルミを成形したフィルムを用いた。吸水材層は、上記のとおり厚さが０．１ｍｍ、０．５ｍｍおよび１．５ｍｍの２種類のものを用意した。粘着剤層２２としては、アクリル系粘着剤によって厚さ０．０５ｍｍの粘着剤層を形成した。カバーフィルム３としては、ポリオレフィンフィルムを用いた。これらの部材を積層し、電極層１２に引き出し配線４１を接続し、電極層１３に引き出し配線４２を接続して、圧電センサを作製した。 As the piezoelectric element 1, a film obtained by molding aluminum nitride on a PET film was used. As described above, two types of water absorbing material layers having thicknesses of 0.1 mm, 0.5 mm, and 1.5 mm were prepared. As the pressure-sensitive adhesive layer 22, a pressure-sensitive adhesive layer having a thickness of 0.05 mm was formed using an acrylic pressure-sensitive adhesive. As the cover film 3, a polyolefin film was used. These members were stacked, a lead wire 41 was connected to the electrode layer 12, and a lead wire 42 was connected to the electrode layer 13 to produce a piezoelectric sensor.
　このようにして得た圧電センサを、粘着剤層で人体の手首の皮膚表面に貼り付け、脈拍により圧電素子で発生する電気信号を測定した。この測定では、オペアンプを用いたチャージアンプを接続して信号強度（電圧）を測定した。 The piezoelectric sensor thus obtained was attached to the skin surface of the human wrist with an adhesive layer, and an electrical signal generated by the piezoelectric element due to the pulse was measured. In this measurement, a signal amplifier (voltage) was measured by connecting a charge amplifier using an operational amplifier.
　シリコーン樹脂層（吸水材層）の厚さが０．１ｍｍ、０．５ｍｍ、１．５ｍｍの場合における脈拍測定時の信号強度の変化を示すグラフをそれぞれ図４～図６に示す。図４～図６から、吸水材層（吸水性粘着層）の厚さが薄い程、信号強度が強くなっており、圧電センサの感度が高くなることが分かる。 FIGS. 4 to 6 are graphs showing changes in signal intensity during pulse measurement when the thickness of the silicone resin layer (water absorbing material layer) is 0.1 mm, 0.5 mm, and 1.5 mm, respectively. 4 to 6, it can be seen that the thinner the water-absorbing material layer (water-absorbing adhesive layer), the stronger the signal intensity and the higher the sensitivity of the piezoelectric sensor.
　今回開示された実施形態および実施例はすべての点で例示であって制限的なものではないと考えられるべきである。本発明の範囲は上記した説明ではなくて請求の範囲によって示され、請求の範囲と均等の意味および範囲内でのすべての変更が含まれることが意図される。 The embodiments and examples disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.
　１　圧電素子、１１　圧電フィルム、１２，１３　電極層、２　吸水性粘着層、２１　吸水材層、２２　粘着剤層、３　カバーフィルム、４１，４２　引き出し配線、５１　アンプ基板、５２　アンプ、５３　シールドケース、６　導電性接着剤。 1 piezoelectric element, 11 piezoelectric film, 12, 13 electrode layer, 2 water absorbing adhesive layer, 21 water absorbing material layer, 22 adhesive layer, 3 cover film, 41, 42 lead wiring, 51 amplifier board, 52 amplifier, 53 shield case , 6 Conductive adhesive.

Claims (7)

  1. 　圧電フィルム、前記圧電フィルムの一方の主面に積層された信号電極層、および、前記圧電フィルムの他方の主面に積層された接地電極層を含む圧電素子と、
    　前記圧電素子の一方の主面側に形成された吸水性粘着層とを備えることを特徴とする、圧電センサ。     A piezoelectric element including a piezoelectric film, a signal electrode layer laminated on one principal surface of the piezoelectric film, and a ground electrode layer laminated on the other principal surface of the piezoelectric film;
    A piezoelectric sensor comprising: a water-absorbing adhesive layer formed on one main surface side of the piezoelectric element.
  2. 　前記吸水性粘着層は、吸水材層と、該吸水材層の前記圧電素子と反対側の主面に積層された透湿性を有する粘着剤層とから構成される、請求項１に記載の圧電センサ。 2. The piezoelectric device according to claim 1, wherein the water-absorbing pressure-sensitive adhesive layer includes a water-absorbing material layer and a moisture-permeable pressure-sensitive adhesive layer laminated on a main surface of the water-absorbing material layer opposite to the piezoelectric element. Sensor.
  3. 　前記吸水性粘着層は、吸水性を有する粘着剤組成物からなる単層である、請求項１に記載の圧電センサ。 The piezoelectric sensor according to claim 1, wherein the water-absorbing pressure-sensitive adhesive layer is a single layer made of a water-absorbing pressure-sensitive adhesive composition.
  4. 　前記信号電極層および前記接地電極層は、耐腐食性の金属からなる、請求項１～３のいずれか１項に記載の圧電センサ。 The piezoelectric sensor according to any one of claims 1 to 3, wherein the signal electrode layer and the ground electrode layer are made of a corrosion-resistant metal.
  5. 　前記吸水性粘着層の厚さが０．６ｍｍ以下である、請求項１～４のいずれか１項に記載の圧電センサ。 The piezoelectric sensor according to any one of claims 1 to 4, wherein the water-absorbing adhesive layer has a thickness of 0.6 mm or less.
  6. 　前記吸水材層の厚さが０．５ｍｍ以下である、請求項２に記載の圧電センサ。 The piezoelectric sensor according to claim 2, wherein the thickness of the water absorbing material layer is 0.5 mm or less.
  7. 　生体に貼り付けた状態で使用される、請求項１～６のいずれか１項に記載の圧電センサ。 The piezoelectric sensor according to any one of claims 1 to 6, which is used in a state of being attached to a living body.
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