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WO2010061726A1 - Matériau piézoélectrique organique, transducteur ultrasonique et sonde ultrasonique - Google Patents

Matériau piézoélectrique organique, transducteur ultrasonique et sonde ultrasonique Download PDF

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Publication number
WO2010061726A1
WO2010061726A1 PCT/JP2009/069175 JP2009069175W WO2010061726A1 WO 2010061726 A1 WO2010061726 A1 WO 2010061726A1 JP 2009069175 W JP2009069175 W JP 2009069175W WO 2010061726 A1 WO2010061726 A1 WO 2010061726A1
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Prior art keywords
ultrasonic
organic piezoelectric
piezoelectric material
organic
ultrasonic transducer
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PCT/JP2009/069175
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English (en)
Japanese (ja)
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葉月 中江
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コニカミノルタエムジー株式会社
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    • 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
    • H10N30/80—Constructional details
    • H10N30/85—Piezoelectric or electrostrictive active materials
    • H10N30/857—Macromolecular compositions
    • 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
    • H10N30/01—Manufacture or treatment
    • H10N30/09—Forming piezoelectric or electrostrictive materials
    • H10N30/098—Forming organic materials
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B06—GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS IN GENERAL
    • B06B—METHODS OR APPARATUS FOR GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS OF INFRASONIC, SONIC, OR ULTRASONIC FREQUENCY, e.g. FOR PERFORMING MECHANICAL WORK IN GENERAL
    • B06B1/00—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency
    • B06B1/02—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy
    • B06B1/06—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with piezoelectric effect or with electrostriction
    • B06B1/0607—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with piezoelectric effect or with electrostriction using multiple elements
    • B06B1/0622—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with piezoelectric effect or with electrostriction using multiple elements on one surface
    • B06B1/064—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with piezoelectric effect or with electrostriction using multiple elements on one surface with multiple active layers

Definitions

  • the present invention relates to an organic piezoelectric material, an ultrasonic transducer, and an ultrasonic probe using the same.
  • Ultrasound is generally referred to as a sound wave of 16000 Hz or higher, and can be examined non-destructively and harmlessly, so that it is applied to various fields such as defect inspection and disease diagnosis.
  • harmonic imaging that forms an image of the internal state in the subject using the harmonic frequency component, not the frequency (fundamental frequency) component of the ultrasound transmitted from the ultrasound probe into the subject ( Harmonic Imaging technology is being researched and developed.
  • This harmonic imaging technology has (1) a low sidelobe level compared to the level of the fundamental frequency component, an improved S / N ratio (signal to noise ratio) and improved contrast resolution, and (2) frequency Increasing the beam width narrows and the lateral resolution is improved.
  • Ultrasonic transducers for detecting received waves containing harmonic frequency components in ultrasonic probes for harmonic imaging require wider bandwidth sensitivity, and are organic polymer materials such as polyvinylidene fluoride (A organic piezoelectric material having PVDF as a main component is known. This organic piezoelectric material has a higher flexibility, thinner film, larger area, longer length, and can be made in any shape and form compared to inorganic piezoelectric materials, etc. Has characteristics.
  • organic piezoelectric materials mainly composed of polyvinylidene fluoride are known to have very weak adhesion to electrode metals, and the electrodes may be peeled off due to friction during operation of the ultrasonic probe. There was a problem that peeling was caused even by weak friction during the process, making it difficult to process.
  • Patent Documents 1 and 2 As a method for solving these problems, it is known that a monomer having an acrylic group is copolymerized or mixed in a copolymer with PVDF polymer and trifluoroethylene (for example, see Patent Documents 1 and 2). Also known is a method of improving the adhesion by surface processing the surface of an organic piezoelectric material by plasma discharge treatment or the like (see, for example, Patent Document 3).
  • an organic binder layer is provided on the electrode, the surface of the organic binder layer is roughened, and a solution containing a fluororesin and a solvent is applied on the roughened organic binder layer to form an organic piezoelectric element.
  • a solution containing a fluororesin and a solvent is applied on the roughened organic binder layer to form an organic piezoelectric element.
  • Copolymerization or mixing of monomers having an acrylic group as described in Patent Document 1 and Patent Document 2 is due to the brittleness inherent in a highly crystalline PVDF polymer and a copolymer of trifluoroethylene. Further worsening is not necessarily desirable for application to an ultrasonic probe applied to a subject.
  • the method of chemically changing the surface may promote the brittleness of the organic piezoelectric material, and even if physical etching is performed. In some cases, sufficient adhesion could not be obtained. In particular, when used for a long time as an ultrasonic vibration probe that oscillates and receives vibrations of several MHz, the adhesiveness may be significantly reduced.
  • the present invention has been made in view of the above problems, and an object of the present invention is to provide an optimum condition for surface treatment for improving the electrode adhesion of an organic piezoelectric material, and to have excellent adhesion to an electrode metal. , Excellent resistance to electrode peeling due to friction during operation, excellent suppression of delamination even with weak friction during processing, organic to form an ultrasonic transducer with excellent piezoelectricity suitable for high frequency and wide band
  • An object is to provide a piezoelectric material, an ultrasonic transducer, and an ultrasonic probe using the piezoelectric material.
  • An organic piezoelectric material for forming an ultrasonic transducer wherein an arithmetic average roughness (Ra) of at least one surface is 0.01 ⁇ m or more and 0.9 ⁇ m or less.
  • organic piezoelectric material according to 1, wherein the organic piezoelectric material has a copolymer of vinylidene fluoride and trifluoroethylene containing 60 to 95 mol% of vinylidene fluoride.
  • An ultrasonic vibrator having an electrode bonded to the one surface of the organic piezoelectric material described in 3.1 or 2.
  • An ultrasonic probe comprising the ultrasonic transducer according to 5.3 or 4.
  • An ultrasonic transducer for transmission that transmits an ultrasonic wave toward a subject by an input electric signal, and the ultrasonic transducer converts an ultrasonic wave received from the subject into an electric signal and outputs the electric signal 5.
  • the arithmetic average roughness (Ra) of at least one surface of the organic piezoelectric material is 0.01 ⁇ m or more and 0.9 ⁇ m or less, so that the adhesive property with the electrode metal is excellent, and the ultrasonic probe.
  • Excellent resistance to electrode peeling due to friction during operation, excellent suppression of delamination generation even with weak friction during processing, excellent workability, adhesive strength that can withstand ultrasonic vibration, and piezoelectricity It is possible to provide an organic piezoelectric material, an ultrasonic transducer, and an ultrasonic probe using the same for forming an ultrasonic transducer suitable for high frequency and wide band.
  • FIG. 1 is an external view illustrating an ultrasonic diagnostic apparatus according to an embodiment. It is a block diagram which shows the electrical structure of the ultrasound diagnosing device in this embodiment. It is typical sectional drawing which shows the structure of the ultrasound probe in the ultrasound diagnosing device of this embodiment.
  • the arithmetic average roughness (Ra) of at least one surface of the organic piezoelectric material is 0.01 ⁇ m or more and 0.9 ⁇ m, so that the adhesion to the electrode metal is excellent. Excellent resistance to electrode peeling due to friction during operation, excellent suppression of delamination due to weak friction during processing, excellent workability, adhesive strength that can withstand ultrasonic vibration, and piezoelectricity And an organic piezoelectric material for forming an ultrasonic transducer suitable for high frequency and wide band.
  • the unevenness of the organic piezoelectric material is defined as the arithmetic average roughness (Ra).
  • the adhesiveness of the organic piezoelectric material is relatively unaffected by specific scratches that occur in minute regions, and the electrodes are joined. This is due to the influence of the unevenness of the entire joint surface. If the Ra value is less than 0.01 ⁇ m, the anchor effect cannot be obtained, so that the adhesiveness is not improved. If the Ra value exceeds 0.9 ⁇ m, the surface uniformity is not good, and the improvement in the adhesiveness is not observed.
  • the arithmetic average roughness (Ra) of the surface means a value obtained by extracting only the reference length in the direction of the average line from the roughness curve and averaging the absolute ground of the deviation from the average line to the measurement curve.
  • the arithmetic average roughness can be measured and determined according to JIS B 0601 using an atomic force microscope (AFM).
  • Organic piezoelectric material as the constituent material of the piezoelectric material constituting the ultrasonic vibrator of the present invention can be adopted regardless of whether it is a low molecular material or a high molecular material.
  • a high molecular organic piezoelectric material for example, polyvinylidene fluoride, a polyvinylidene fluoride copolymer, a polyvinylidene cyanide or a vinylidene cyanide copolymer, an odd-numbered nylon such as nylon 9 or nylon 11, or an aromatic Aromatic nylon, alicyclic nylon, polylactic acid, polyhydroxycarboxylic acids such as polyhydroxybutyrate, cellulose derivatives, polyurea and the like.
  • a polymer organic piezoelectric material particularly a polymer material mainly composed of vinylidene fluoride is preferable.
  • it is preferably a homopolymer of polyvinylidene fluoride having a CF 2 group having a large dipole moment or a copolymer having vinylidene fluoride as a main component.
  • tetrafluoroethylene, trifluoroethylene, hexafluoropropene, chlorofluoroethylene, etc. can be used as the second component in the copolymer.
  • the electromechanical coupling constant (piezoelectric effect) in the thickness direction varies depending on the copolymerization ratio.
  • the copolymerization ratio of vinylidene fluoride is 60 to 99 mol%, and furthermore, 85 to 99 mol. % Is preferred.
  • the copolymerization ratio of vinylidene fluoride is 60 mol% or more and 95% or less, and the copolymerization ratio of trifluoroethylene is 5 mol. % To 40 mol% is more preferable.
  • An organic piezoelectric material containing 85 to 99 mol% of vinylidene fluoride and 1 to 15 mol% of perfluoroalkyl vinyl ether, perfluoroalkoxyethylene, perfluorohexaethylene, etc. was applied to an ultrasonic probe. In some cases, it is possible to suppress the transmission fundamental wave and increase the sensitivity of harmonic reception.
  • the organic piezoelectric material can be made thinner than an inorganic piezoelectric material made of ceramics, the organic piezoelectric material is characterized in that it can be used as a vibrator corresponding to transmission and reception of higher frequencies.
  • the organic piezoelectric material according to the present embodiment preferably has a relative dielectric constant of 10 to 50 at the thickness resonance frequency.
  • the relative dielectric constant can be adjusted by adjusting the number, composition, polymerization degree, etc. of polar functional groups such as CF 2 groups and CN groups contained in the compound constituting the organic piezoelectric material, and polarization treatment described later. .
  • an ultrasonic vibrator in which the organic piezoelectric material according to the present embodiment and a plurality of polymer materials are laminated can also be configured.
  • the polymer material to be laminated the following polymer material having a relatively low relative dielectric constant can be used in addition to the above polymer material.
  • the numerical value in parentheses indicates the relative dielectric constant of the polymer material (resin).
  • the polymer material having a low relative dielectric constant is preferably selected in accordance with various purposes such as adjusting the piezoelectric characteristics or imparting the physical strength of the organic piezoelectric film. .
  • the organic piezoelectric material according to the present embodiment can be manufactured by various methods using the polymer material as a main constituent.
  • a general method such as a melting method or a casting method can be used.
  • a polyvinylidene fluoride-trifluoroethylene copolymer it is known that it has a crystalline form with spontaneous polarization only when it is made into a film, but in order to further improve the characteristics, a process for aligning the molecular arrangement should be added. Is useful. Examples of means include stretching film formation and polarization treatment.
  • the stretching film forming method various known methods can be employed. For example, a solution obtained by dissolving the above polymer material in an organic solvent such as ethyl methyl ketone (MEK) is cast on a substrate such as a glass plate, and the solvent is dried at room temperature to obtain a film having a desired thickness. The film is stretched to a predetermined length at room temperature. The stretching can be performed in uniaxial and biaxial directions so that the organic piezoelectric film having a predetermined shape is not broken.
  • the draw ratio is 2 to 10 times, preferably 2 to 6 times.
  • the melt flow rate at 230 ° C. is 0.03 g / min or less. More preferably, a high-sensitivity piezoelectric thin film can be obtained by using a polymer piezoelectric body of 0.02 g / min or less, more preferably 0.01 g / min.
  • Relaxing treatment can be applied to the stretched organic piezoelectric material.
  • the flexibility, weakening, flatness, etc. of the organic piezoelectric material can be improved.
  • the relaxation treatment is a process in which the stress at both ends of the organic piezoelectric material is changed while following the contraction or expansion force applied to the film-like organic piezoelectric material in the process of cooling to room temperature after the heat treatment. is there.
  • Relaxation treatment does not stretch in the direction in which tension is applied even if it is shrunk so as to relieve stress unless the organic piezoelectric material relaxes and flatness cannot be maintained or the stress increases and breaks. It may be spread over.
  • the amount of relaxation treatment in the present invention is about 10% in length when the stretched direction is determined to be positive, and about 15% in order to follow slack when the film stretches during cooling. It is preferred to do so.
  • the end is supported by a chuck, a clip, etc., and the temperature is 10 ° C. lower than the melting point of the organic piezoelectric material. It is preferable to place it near the temperature with the upper limit being.
  • the melting point is 150 ° C. to 180 ° C., and therefore, it is preferable to perform heat treatment at a temperature of 100 ° C. or more and 140 ° C. or less.
  • the longer the time is, the longer the effect is expressed and the longer the effect is exhibited, the longer the crystal growth is promoted. However, since the saturation occurs with time, it is practically about 10 hours and at most about day and night.
  • Ra surface processing of organic piezoelectric material front and back Various known methods can be employed for the surface treatment of setting the Ra on the front and back surfaces of the organic piezoelectric material according to the present embodiment to 0.01 to 0.9 ⁇ m.
  • rough surface processing can be performed by atmospheric pressure plasma treatment, reduced pressure plasma treatment, corona discharge treatment, precision polishing, and the like.
  • the surface processing is not limited to these, but is preferably performed in an inert gas atmosphere that does not cause a chemical change on the surface of the organic piezoelectric material.
  • Ra can be made desired by appropriately selecting the treatment time, the voltage to be applied, the particle size of the abrasive, and the like.
  • the organic piezoelectric material according to the present embodiment can be subjected to polarization treatment.
  • polarization processing method a conventionally known method such as DC voltage application processing, AC voltage application processing, or corona discharge processing can be applied.
  • the corona discharge treatment can be performed by using a commercially available apparatus comprising a high voltage power source and electrodes.
  • the voltage of the high voltage power source is preferably ⁇ 1 to ⁇ 20 kV, the current is 1 to 80 mA, the distance between the electrodes is preferably 1 to 10 cm, and the applied voltage is preferably 0.5 to 2.0 MV / m. .
  • the discharge electrode a needle electrode, a wire electrode (wire electrode), and a mesh electrode that have been conventionally used are preferable, but the present invention is not limited thereto.
  • the polarization treatment may be performed after forming the electrodes placed on either the front or back surface of the organic piezoelectric material.
  • the ultrasonic transducer is configured by arranging a pair of electrodes with a film-like organic piezoelectric material interposed therebetween, and an ultrasonic probe is configured by arranging a plurality of transducers, for example, one-dimensionally.
  • the ultrasonic transducer having the organic piezoelectric material according to the present embodiment is manufactured by forming electrodes on both sides or one side of the organic piezoelectric material and polarizing the piezoelectric film.
  • the electrode is formed using an electrode material mainly composed of gold (Au), platinum (Pt), silver (Ag), palladium (Pd), copper (Cu), nickel (Ni), tin (Sn), or the like. .
  • a base metal such as titanium (Ti) or chromium (Cr) is formed to a thickness of 0.02 to 1.0 ⁇ m by sputtering.
  • these electrodes can be formed by screen printing, dipping, or thermal spraying using a conductive paste in which fine metal powder and low-melting glass are mixed.
  • a piezoelectric element can be obtained by supplying a predetermined voltage between the electrodes formed on both surfaces of the piezoelectric film to polarize the piezoelectric film.
  • the thickness of the organic piezoelectric material can be made uniform so that the direction in which the organic piezoelectric material is relaxed and the long side direction of the rectangular ultrasonic transducer are parallel to each other. This is preferable in that stable piezoelectric performance can be obtained.
  • FIG. 1 is an external view of the ultrasonic diagnostic apparatus according to the present embodiment
  • FIG. 2 is a block diagram illustrating an electrical configuration of the ultrasonic diagnostic apparatus according to the present embodiment.
  • the ultrasonic diagnostic apparatus S transmits an ultrasonic wave to a subject (not shown) and receives an ultrasonic wave reflected from the subject, an ultrasonic probe 2, and a cable. 3, and by transmitting a transmission signal of an electrical signal to the ultrasonic probe 2 via the cable 3, the ultrasonic probe 2 transmits ultrasonic waves to the subject, Based on the received signal of the electric signal generated by the ultrasonic probe 2 in accordance with the reflected wave of the ultrasonic wave from the inside of the subject received by the probe 2, the internal state in the subject is converted into an ultrasonic image. And an ultrasonic diagnostic apparatus main body 1 for imaging.
  • the ultrasonic diagnostic apparatus main body 1 includes an operation input unit 11 for inputting data such as a command for starting diagnosis and personal information of a subject, and a cable 3 to the ultrasonic probe 2.
  • a transmission circuit 12 for supplying a transmission signal of an electrical signal via the transmitter and generating an ultrasonic wave in the ultrasonic probe 2 and reception for receiving a reception signal of the electrical signal from the ultrasonic probe 2 via the cable 3
  • the circuit 13 an image processing unit 14 that generates an image (ultrasonic image) of the internal state in the subject based on the reception signal received by the receiving circuit 13, and the internal part in the subject generated by the image processing unit 14
  • the ultrasonic diagnostic apparatus S as a whole is controlled by controlling the display unit 15 that displays the state image and the operation input unit 11, the transmission circuit 12, the reception circuit 13, the image processing unit 14, and the display unit 15 according to the function.
  • Control unit 16 that performs control Equipped with a.
  • the ultrasonic probe 2 includes a plurality of inorganic piezoelectric elements and a plurality of organic piezoelectric elements.
  • Each of the inorganic piezoelectric elements includes an inorganic piezoelectric material, and a plurality of inorganic piezoelectric elements capable of mutually converting signals between an electric signal and an ultrasonic signal by using a piezoelectric phenomenon, and the present embodiment
  • An organic piezoelectric element that is an ultrasonic vibrator including an organic piezoelectric material according to a form includes an organic piezoelectric element that can mutually convert a signal between an electrical signal and an ultrasonic signal by using a piezoelectric phenomenon. It has.
  • FIG. 3 is a schematic cross-sectional view showing the configuration of the ultrasonic probe in the ultrasonic diagnostic apparatus of the present embodiment.
  • the ultrasonic probe 2 ⁇ / b> A is laminated on the flat acoustic braking member 23, the plurality of inorganic piezoelectric elements 22 stacked on one main surface of the acoustic braking member 23, and the plurality of inorganic piezoelectric elements 22.
  • the intermediate layer 26, the plurality of organic piezoelectric elements 21 stacked on the intermediate layer 26, the acoustic matching layer 27 stacked on the organic piezoelectric element 21, the plurality of inorganic piezoelectric elements 22 and the plurality of organic layers And an acoustic absorber 24 filled in a gap in the piezoelectric element 21.
  • the acoustic braking member 23 is made of a material that absorbs ultrasonic waves, and absorbs ultrasonic waves radiated from the plurality of inorganic piezoelectric elements 22 toward the acoustic absorbing member 23.
  • Each inorganic piezoelectric element 22 in the plurality of inorganic piezoelectric elements 22 includes electrodes 2021 and 2031 on opposite surfaces of a piezoelectric body 2011 made of an inorganic piezoelectric material.
  • the plurality of inorganic piezoelectric elements 22 are arranged on the acoustic braking member 23 in a two-dimensional array in plan view with a predetermined interval therebetween.
  • the plurality of inorganic piezoelectric elements 22 may be configured to receive reflected ultrasonic waves, but the ultrasonic probe 2A and the ultrasonic diagnostic apparatus S in the present embodiment transmit ultrasonic waves. It is configured. That is, the inorganic piezoelectric element 22 functions as an ultrasonic transducer for transmission.
  • an electrical signal is input to the plurality of inorganic piezoelectric elements 22 from the transmission circuit 12 via the cable 3.
  • This electrical signal is input to the electrodes 2021 and 2031 of the inorganic piezoelectric element 22.
  • the plurality of inorganic piezoelectric elements 22 transmit this ultrasonic signal by converting this electric signal into an ultrasonic signal.
  • the acoustic absorber 24 is made of a material that absorbs ultrasonic waves, and is for reducing mutual interference between the plurality of inorganic piezoelectric elements 22 and organic piezoelectric elements 21.
  • the acoustic absorber 24 can reduce crosstalk between the inorganic piezoelectric elements 22 and the organic piezoelectric elements 21.
  • the intermediate layer 26 is a member for laminating the plurality of inorganic piezoelectric elements 22 and the organic piezoelectric elements 21, and matches the acoustic impedance between the plurality of inorganic piezoelectric elements 22 and the organic piezoelectric elements 21.
  • the organic piezoelectric element 21 includes a piezoelectric body 101 made of an organic piezoelectric material according to the present embodiment, and electrodes 102 and 103 on both surfaces of the piezoelectric body 101 facing each other. Similar to the inorganic piezoelectric element 22, the plurality of organic piezoelectric elements 21 are arranged on the intermediate layer 26 in a two-dimensional array in plan view at a predetermined interval.
  • the plurality of organic piezoelectric elements 21 are laminated on the plurality of inorganic piezoelectric elements 22 on the acoustic braking member 23 by vapor-depositing a metal serving as an electrode on the front and back surfaces of an integral sheet-like organic piezoelectric material by a known method. After bonding on the intermediate layer 26, they are separated individually by cutting together with the intermediate layer 26 so as to form the same two-dimensional array as the plurality of inorganic piezoelectric elements 22 with a dicing saw.
  • the organic piezoelectric element 21 may be configured to transmit ultrasonic waves, but the ultrasonic probe 2A and the ultrasonic diagnostic apparatus S in the present embodiment are configured to receive ultrasonic reflected waves. ing. More specifically, the organic piezoelectric element 21 receives an ultrasonic signal of a reflected wave, and outputs the electric signal by converting the ultrasonic signal into an electric signal. This electrical signal is output from the electrode 102 and the electrode 103 in the organic piezoelectric element 21. This electrical signal is output to the receiving circuit 13 via the cable 3.
  • the acoustic matching layer 27 is a member that matches the acoustic impedance of the inorganic piezoelectric element 22 and the acoustic impedance of the subject and matches the acoustic impedance of the organic piezoelectric element 21 and the acoustic impedance of the subject.
  • the acoustic matching layer 27 includes an acoustic lens that converges an ultrasonic wave that is transmitted toward the subject, and has an arcuate shape.
  • the organic piezoelectric element 21 is stacked on the subject side (in the direction indicated by the arrow X) of the inorganic piezoelectric element 22, so that the ultrasonic wave transmitted from the inorganic piezoelectric element 22 is transmitted. You will receive sound waves at close range. Therefore, the piezoelectric body 101 and the electrodes 102 and 103 tend to be exfoliated by ultrasonic waves transmitted from the inorganic piezoelectric element 21.
  • the organic piezoelectric material according to the present embodiment to the organic piezoelectric element 21, the adhesive strength between the piezoelectric body 101 and the electrodes 102 and 103 is maintained even during long-term use, and no peeling occurs. It becomes.
  • the transmission circuit 12 When a diagnosis start instruction is input from the operation input unit 11, the transmission circuit 12 generates an electric signal transmission signal under the control of the control unit 16.
  • the generated electrical signal transmission signal is supplied to the ultrasonic probe 2 via the cable 3. More specifically, this electrical signal transmission signal is supplied to each of the plurality of inorganic piezoelectric elements 22 in the ultrasonic probe 2.
  • the electric signal transmission signal is, for example, a voltage pulse repeated at a predetermined cycle.
  • Each of the plurality of inorganic piezoelectric elements 22 expands and contracts in the thickness direction when supplied with the transmission signal of the electric signal, and ultrasonically vibrates according to the transmission signal of the electric signal.
  • the plurality of inorganic piezoelectric elements 22 radiate ultrasonic waves through the intermediate layer 26, the organic piezoelectric element 21 and the acoustic matching layer 27.
  • ultrasonic waves are transmitted from the ultrasonic probe 2 to the subject.
  • the ultrasound probe 2 may be used in contact with the surface of the subject, or may be used by being inserted into the subject, for example, being inserted into a body cavity of a living body. .
  • the ultrasonic wave transmitted to the subject is reflected at one or a plurality of boundary surfaces having different acoustic impedances inside the subject, and becomes a reflected wave of the ultrasonic wave.
  • This reflected wave includes not only the frequency component of the transmitted ultrasonic wave (fundamental fundamental frequency) but also the frequency component of a harmonic that is an integral multiple of the fundamental frequency. For example, second harmonic components such as twice, three times, and four times the fundamental frequency, third harmonic components, and fourth harmonic components are also included.
  • the ultrasonic wave of the reflected wave is received by the ultrasonic probe 2.
  • the ultrasonic wave of the reflected wave is received by the organic piezoelectric element 21 through the acoustic matching layer 27, and mechanical vibration is converted into an electric signal by the organic piezoelectric element 21 and is extracted as a received signal.
  • the extracted reception signal of the electrical signal is received by the receiving circuit 13 controlled by the control unit 16 via the cable 3.
  • ultrasonic waves are sequentially transmitted from the inorganic piezoelectric elements 22 toward the subject, and the ultrasonic waves reflected by the subject are received by the organic piezoelectric elements 21.
  • the image processing unit 14 controls the image of the internal state in the subject (ultrasonic image) based on the reception signal received by the receiving circuit 13 based on the reception signal received by the reception circuit 13 based on the time from transmission to reception and the reception intensity.
  • the display unit 15 displays the image of the internal state in the subject generated by the image processing unit 14 under the control of the control unit 16.
  • the ultrasonic probe 2A and the ultrasonic diagnostic apparatus S in the present embodiment since the harmonics of the fundamental wave are received as described above, an ultrasonic image can be formed by the harmonic imaging technique. For this reason, the ultrasonic probe 2A and the ultrasonic diagnostic apparatus S in the present embodiment can provide a more accurate ultrasonic image. Since the second and third harmonics having relatively high power are received, a clearer ultrasonic image can be provided.
  • the plurality of inorganic piezoelectric elements 22 are configured to transmit ultrasonic waves. Since the ultrasonic signal is transmitted by the inorganic piezoelectric element 22 capable of increasing the transmission power in this way, the ultrasonic probe 2A and the ultrasonic diagnostic apparatus S increase the transmission power with a relatively simple structure. can do. Therefore, the ultrasonic probe 2A and the ultrasonic diagnostic apparatus S in the present embodiment transmit the fundamental wave with a sound pressure sufficient to obtain the echo of the harmonic generated in the subject with the ultrasonic probe 2A. This is suitable for the harmonic imaging technique that needs to be performed, and it is possible to provide a more accurate ultrasonic image.
  • the organic piezoelectric element 21 is configured to receive an ultrasonic reflected wave.
  • a piezoelectric element made of an inorganic piezoelectric material can receive only an ultrasonic wave having a frequency about twice the frequency of the fundamental wave, but a piezoelectric element made of an organic piezoelectric material is about 4 to 5 times the frequency of the fundamental wave, for example. It is possible to receive an ultrasonic wave having a frequency of 5 and is suitable for widening the reception frequency band.
  • the ultrasonic probe 2A and the ultrasonic diagnostic apparatus S in the present embodiment are compared.
  • the frequency band can be widened with a simple structure.
  • the ultrasonic probe 2A and the ultrasonic diagnostic apparatus S in the present embodiment are suitable for harmonic imaging technology that needs to receive the third and higher harmonics of the fundamental wave, and more accurate ultrasonic waves. Images can be provided.
  • the ultrasonic diagnostic apparatus by utilizing the characteristics of the ultrasonic wave receiving vibrator excellent in piezoelectric characteristics and heat resistance of the present invention and suitable for high frequency and wide band, the image quality and its An ultrasonic image with improved reproduction and stability, particularly durability, can be obtained.
  • Example 1 Production of organic piezoelectric film material >> A polyvinylidene fluoride copolymer having a molar ratio of vinylidene fluoride (hereinafter referred to as VDF) and trifluoroethylene (hereinafter referred to as 3FE) of 75:25 prepared according to the method described in European Patent No. 626,396 is prepared at 50 ° C. A solution of methyl ethyl ketone (hereinafter referred to as MEK) and N, N-dimethylformamide (hereinafter referred to as DMF) in a 9: 1 mixed solvent was cast on a glass plate. Thereafter, the solvent was dried at 55 ° C. to obtain a film (organic piezoelectric material) having a thickness of about 120 ⁇ m.
  • VDF vinylidene fluoride
  • 3FE trifluoroethylene
  • the film was stretched 4 times in a uniaxial direction at room temperature, then heat-treated at 135 ° C. for 1 hour while maintaining the stretched length, and then naturally cooled.
  • the film thickness of the obtained film 1 after the heat treatment was 43 ⁇ m.
  • the electrode was subjected to polarization treatment while applying an AC voltage of 0.1 Hz at room temperature to obtain an organic piezoelectric material sample 1 having electrodes on the front and back surfaces.
  • the polarization process was performed from a low voltage, and the voltage was gradually applied until the electric field between the electrodes finally reached 100 MV / m.
  • the organic piezoelectric material sample 2 is the same as the organic piezoelectric material sample 1 except that the arithmetic mean roughness (Ra) is changed to 0.05 ⁇ m, 0.1 ⁇ m, and 0.9 ⁇ m by changing the processing time of the atmospheric pressure plasma processing. ⁇ 4 were obtained.
  • An organic piezoelectric material sample 5 was obtained by directly depositing gold on the film 1 without performing plasma treatment to produce an electrode, and subsequently performing a polarization treatment in the same manner as the organic piezoelectric material sample 1. .
  • organic piezoelectric material body samples 6 and 7 were prepared in the same manner as the organic piezoelectric material sample 1 except that the arithmetic mean roughness (Ra) was changed to 0.005 ⁇ m and 1.5 ⁇ m by changing the processing time of the atmospheric pressure plasma processing. Obtained.
  • the organic piezoelectric material is the same as the organic piezoelectric material samples 1 to 4, 6, and 7 except that the organic piezoelectric material is a PVDF homopolymer organic piezoelectric film (manufactured by Atchem).
  • the film manufactured by Atchem was subjected to atmospheric pressure plasma treatment to obtain an organic piezoelectric material sample 8.
  • the arithmetic average roughness (Ra) was 0.1 ⁇ m.
  • Adhesiveness immediately after deposition electrode production Adhesion was measured by a 90 degree peel test. Specifically, adhesive was applied to the surface of the electrode deposited on Samples 1 to 8, and Kapton Silicone tape (trade name: Kapton Tape (P221), manufactured by Permacel), manufacturer name: Permacel, specification thickness 25 ⁇ m, silicone The maximum force required for peeling when the silicone-made Kapton tape was peeled in the normal direction of the adhesive surface was measured after the heat treatment by pressure bonding, and evaluated as adhesiveness according to the following evaluation criteria.
  • AS ONE product name US CLLEANER model number US-5R an ultrasonic cleaning machine
  • Electrode durability [Method for evaluating organic piezoelectric material]
  • Lead electrodes are attached to the electrodes on both sides of the organic piezoelectric material body samples 1 to 8 with electrodes obtained as described above, and an impedance analyzer 4294A manufactured by Agilent Technologies is used, and an atmosphere of 25 ° C., from 40 Hz to 110 MHz. The frequency was swept at 600 points at equal intervals. The value of the relative dielectric constant at the thickness resonance frequency was obtained. Similarly, when the peak frequency P of the resistance value near the thickness resonance frequency and the peak frequency S of the conductance were obtained, the electromechanical coupling constant kt was obtained by the following equation.
  • the piezoelectricity was evaluated according to the following evaluation criteria. Evaluation criteria ⁇ : 0.2 or more ⁇ : less than 0.2 The results are shown in Table 1.
  • the adhesiveness was improved by setting the arithmetic average roughness (Ra) to 0.01 to 0.9 ⁇ m. In addition, there was no decrease in piezoelectricity due to the surface treatment.
  • the sample using the polyvinylidene fluoride copolymer having a molar ratio of VDF and 3FE of 75:25 is higher than the sample 8 which is a PVDF homopolymer, in addition to the higher adhesion immediately after the deposition, It is also seen that there is little decrease in adhesion due to ultrasonic irradiation.

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Physics & Mathematics (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Ultra Sonic Daignosis Equipment (AREA)

Abstract

La présente invention permet d’obtenir les conditions de traitement de surface optimales requises pour réaliser une excellente adhésion d’un matériau piézoélectrique organique à une électrode.  L’invention concerne aussi un matériau piézoélectrique organique qui présente une excellente adhésion au métal d’une électrode et d’excellentes caractéristiques de résistance à l’écaillage d’une électrode en raison des frictions pendant le fonctionnement, qui permet de supprimer de manière excellente l’écaillage même dû à une faible friction générée pendant le traitement, et convient à une utilisant dans les hautes fréquences et les larges bandes avec d’excellentes caractéristiques piézoélectriques, un transducteur ultrasonique, et une sonde ultrasonique utilisant le transducteur ultrasonique.  Le matériau piézoélectrique organique pour former le transducteur ultrasonique est caractérisé en ce que la rugosité moyenne arithmétique (Ra) d’au moins une surface est comprise entre 0,01 µm et 0,9 µm.
PCT/JP2009/069175 2008-11-25 2009-11-11 Matériau piézoélectrique organique, transducteur ultrasonique et sonde ultrasonique WO2010061726A1 (fr)

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JP2012068209A (ja) * 2010-09-27 2012-04-05 Choonpa Zairyo Shindan Kenkyusho:Kk 超音波材料診断方法及び装置
JP2012205828A (ja) * 2011-03-30 2012-10-25 Fujifilm Corp 超音波探触子および超音波診断装置
WO2016027587A1 (fr) * 2014-08-22 2016-02-25 三井化学株式会社 Film piézoélectrique polymère
JP2019067908A (ja) * 2017-09-29 2019-04-25 株式会社クレハ 圧電フィルムおよびフィルムの製造方法
CN110832653A (zh) * 2017-07-07 2020-02-21 大金工业株式会社 振动传感器和压电元件

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WO2008015917A1 (fr) * 2006-08-02 2008-02-07 Konica Minolta Medical & Graphic, Inc. Sonde à ultrasons et son procédé de fabrication
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