EP0227985A2 - Sonde ultrasonique - Google Patents

Sonde ultrasonique Download PDF

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Publication number
EP0227985A2
EP0227985A2 EP86117065A EP86117065A EP0227985A2 EP 0227985 A2 EP0227985 A2 EP 0227985A2 EP 86117065 A EP86117065 A EP 86117065A EP 86117065 A EP86117065 A EP 86117065A EP 0227985 A2 EP0227985 A2 EP 0227985A2
Authority
EP
European Patent Office
Prior art keywords
electrodes
polymer film
ultrasonic sensor
sensor according
membrane
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP86117065A
Other languages
German (de)
English (en)
Other versions
EP0227985A3 (en
EP0227985B1 (fr
Inventor
Bernd Dr. Granz
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Siemens AG
Siemens Corp
Original Assignee
Siemens AG
Siemens Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Siemens AG, Siemens Corp filed Critical Siemens AG
Publication of EP0227985A2 publication Critical patent/EP0227985A2/fr
Publication of EP0227985A3 publication Critical patent/EP0227985A3/de
Application granted granted Critical
Publication of EP0227985B1 publication Critical patent/EP0227985B1/fr
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • 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
    • B06B1/0688—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 with foil-type piezoelectric elements, e.g. PVDF
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S310/00—Electrical generator or motor structure
    • Y10S310/80—Piezoelectric polymers, e.g. PVDF

Definitions

  • the invention relates to an ultrasound sensor with a polymer film attached to a support body at least in its edge region, which is piezoelectrically activated at least in a partial region, which is electrically coupled to electrodes.
  • So-called miniature or membrane hydrophones are used to determine the properties of an ultrasound field prevailing in a sound-carrying medium, for example water.
  • the three-dimensional distribution of the sound pressure amplitude of the ultrasound field is determined by measuring the sound pressure prevailing at different locations in a measuring trough with such a hydrophone.
  • a miniature hydrophone in which a piezoactive film made of polyvinylidene fluoride PVDF with electrodes on both of its flat sides and with a thickness of 25 ⁇ m is stretched onto the end face of a stainless steel tube in an electrically insulated manner.
  • the diameter of the film is about 1 mm.
  • a platinum wire is attached to the inside of the film and is connected to the inner conductor of a coaxial cable. This platinum wire is supported by a backing that fills the interior of the stainless steel tube.
  • the outside of the film is electrical with the stainless steel tube contacted and connected to the shield of the coaxial cable.
  • a major advantage of such hydrophones is that the acoustic impedance of their piezoelectric elements is better matched to the acoustic impedance of water than would be the case if a piezoceramic material were used. Compared to piezoceramic sensors, this results in both an increased frequency bandwidth and a reduced disruptive influence on the ultrasound field at the measurement location.
  • the invention is therefore based on the object of specifying an ultrasonic sensor whose piezoelectric element consists of a polymer and which can also be used when measuring high-energy ultrasonic shock waves.
  • the surface charge vibrations in the piezoelectrically active area of the polymer film caused by an ultrasonic wave are electrically coupled via the medium surrounding the polymer film to the electrodes arranged outside the surface area of the polymer film assigned to the piezoelectrically active area of the polymer film .
  • the piezoelectrically active central area of the polymer film can thus be arranged in the focus area of a focused ultrasound shock wave, since there is no mechanically unstable electrically conductive layer in the sensitive area of the polymer film.
  • the invention is based in part on the knowledge that by using a piezoelectric polymer with a piezoceramic material relatively low dielectric constant, a purely capacitive coupling without high signal losses is possible. Accordingly, the electrodes can be attached spatially separated from the piezoelectrically active region of the polymer film both on the film itself and outside of the film, for example on the support body.
  • the electrodes are advantageously designed in such a way that their mutual capacitance is as small as possible compared to the coupling capacitances, in order to reduce the signal losses occurring due to parasitic capacitances.
  • One of the electrodes is connected to the electrical ground of the system.
  • the coupling capacities to the electrodes are as large as possible. Since, as a rule, the environment of the ultrasound sensor is approximately at ground potential during the measurement, the coupling capacitance of the piezoelectrically active region in particular can be increased by suitable design measures without additional signal-reducing parasitic capacitances occurring.
  • a flat, also membrane-like additional ground electrode can be arranged in the ultrasonic sensor opposite the piezoelectrically active region of the membrane parallel to its surface. As a result, the piezoelectrically active region is particularly effectively capacitively coupled to ground.
  • cover plates are arranged on the free end faces of the support body opposite the two flat sides of the membrane.
  • a tight chamber is created between the cover plate and the membrane, containing a sound-carrying liquid is filled.
  • the polarization of the polymer film takes place in an advantageous manner in that it is clamped between movably arranged electrodes located opposite one another and connected to a high voltage.
  • the geometrical shape of the end face of these electrodes thus determines the geometrical shape of the piezoelectrically active region of the polymer film.
  • electrodes for polarization the end faces of which are provided with an electrically conductive, elastic stamp.
  • an ultrasound sensor 2 contains a polymer film 4, for example in the form of a circular disk, which is clamped tightly between two, for example, annular support bodies 6 and forms a membrane 40.
  • the polymer film consists of a semicrystalline polymer, for example polyvinyl fluoride PVF or a copolymer of vinyl fluoride with tetrafluoroethylene or trifluoroethylene, in particular biaxially stretched polyvinylidene fluoride PVDF.
  • the polymer film 4 is polarized in a central region 42 and is piezoelectrically active.
  • the piezoelectrically active area 42 is surrounded by a piezoelectrically inactive area 44.
  • the diameter d of the central region 42 is very much smaller than the diameter D of the membrane 40 of the polymer film 4.
  • the diameter d of the polarized central region Area 42 smaller than 2 mm, in particular smaller than 1 mm.
  • the diameter D of the membrane 40 is advantageously greater than 30 mm, in particular greater than 50 mm choose to reduce the influence of the support body 6 on the sound field to be measured in the central area 42.
  • the thickness of the polymer film 4 is between 10 ⁇ m and 100 ⁇ m, in particular between 25 ⁇ m and 50 ⁇ m.
  • the polymer film 4 is provided on the surface of its piezoelectrically inactive region 44 on its two flat sides with one electrode 8 each.
  • the electrodes 8 are thus arranged in such a way that they are spatially separated from the piezoelectrically active region 42 and do not touch it.
  • the electrodes 8 are preferably located in an outer edge region of the polymer film 4, the width of which is less than 1/4, in particular less than 1/10, of the diameter of the film.
  • the electrodes 8 have an annular shape, for example, and are arranged, for example, concentrically around the central axis 22 in the region of the membrane 40.
  • the electrodes 8 are provided with electrical connection conductors 82, which lead, for example, in radial grooves 62 of the support body 6 to the cylindrical outer edge of the ultrasonic sensor 2.
  • the connecting conductors 82 can be connected, for example, with a coaxial cable, which forwards the electrical signals to further processing electronics, for example a charge-sensitive amplifier.
  • one of the two connection conductors 82 is connected to the electrical ground.
  • the properties of the ultrasound field of an ultrasound transmitter used for medical purposes are generally measured in a basin filled with a sound-carrying liquid, for example water.
  • the ultrasonic sensor 2 is thus surrounded by water 10 during the measurement.
  • the pressure acting on the polymer film 4 through the ultrasonic field Forces generate 42 high-frequency surface charge vibrations in the piezoelectrically active central region.
  • the signal-receiving electrodes 8 are arranged on the outer edge of the membrane area of the polymer film 4, very high sound pressure amplitudes can be measured reproducibly in the central area 40 without the risk of mechanical destruction and the electrodes 8 flaking off the polymer film 4.
  • the electrodes 8 can also extend into the area of the polymer film 4 which is clamped between the support bodies 6.
  • the grooves 64 in which the connecting conductors 82 run no longer have to extend to the inner edge of the support body 6.
  • the two flat sides of the polymer film 4 are each provided with an approximately semi-ring-shaped electrode 86 or 87.
  • the two electrodes 86 and 87 are arranged such that they do not overlap.
  • the parasitic capacitance which occurs between the electrodes 86 and 87 and which causes a reduction in the electrical useful signal is thereby reduced. This is particularly advantageous if the ultrasound sensor is also to be used for measuring ultrasound fields that are used in medical diagnostics.
  • one of the two support bodies 6 is provided with a ground electrode 12 on its flat side facing away from the polymer film 4.
  • This ground electrode 12 is connected to the electrical ground together with that electrode 8 which is located in the region between the ground electrode 12 and the polymer film 4.
  • the ground electrode 12 consists of a stainless steel foil, the thickness of which is less than 100 ⁇ m, in particular between 10 ⁇ m and 20 ⁇ m.
  • the ground electrode 12 is a thin metal grid, the thickness of which is also less than 100 ⁇ m. This reduces the disruptive influence of the ground electrode 12 on the ultrasonic field.
  • the electrode 8 located between the ground electrode 12 and the polymer film 4 can also be omitted, since the ground electrode 12 takes over the function of this electrode 8.
  • the support bodies 6 are each provided with a cover plate 122 or 124 on their flat sides facing away from the polymer film 4. Between the membrane area 40 of the polymer film 4 and the cover plates 122 and 124, a sealed chamber 100 is thus created.
  • these cover plates 122 and 124 consist of a plastic, for example polystyrene PS or polymethacrylic acid methyl ester PMMA, which is the sound-carrying material located outside the chamber 100 Liquid largely adapted acoustically and its influence on the sound field to be measured is low.
  • the cover plates 122 and 124 consist of polymethylpentene, PMP, whose acoustic impedance is almost equal to the acoustic impedance of water.
  • the cover plates 122 and 124 can also consist of a polymer film, the thickness of which is preferably less than 100 ⁇ m.
  • the chambers 100 are sealed off from the outside space and are separated from one another by the polymer film 4.
  • the grooves 62 in which the connecting conductors 82 run for example partially potted with an adhesive 84, or an embodiment according to FIG. 2 is provided in which the grooves do not lead to the inner edge of the support body 6.
  • the chambers 100 are filled with a sound-carrying liquid.
  • Water can be provided as the liquid, for example, in which the signal coupling from the piezoelectrically active central region 42 to the contact electrodes 8 takes place essentially capacitively.
  • the chambers 100 are filled with an electrolyte, for example an aqueous saline solution, the electrical conductivity of which is selected such that the ohmic resistance between the electrodes 8 and the surface of the piezoactive region 42 is less than 1 k ⁇ , in particular less than 100 ⁇ is.
  • the alternating charge signal generated in the piezoelectrically active region 42 is coupled to the electrodes 8 in a first approximation via the series resistance formed by the liquid.
  • At least the surface of the electrodes 8 advantageously consists of a noble metal material, for example gold Au or platinum Pt.
  • one of the cover plates 122 and 124 can also consist of an electrically conductive material, for example a stainless steel foil or an electrically conductive plastic, and can be connected to the electrical ground. As a result, the coupling capacitance of the piezoelectrically active region 42 is increased to ground and the electrical output signal is increased accordingly.
  • one of the cover plates 122 and 124 consists of a metallic material, the ultrasound sensor 2 is to be used in a measurement in an advantageous manner in the sound field of an ultrasound transmitter such that this cover plate is on the side of the ultrasound sensor facing away from the ultrasound transmitter 2 is located.
  • a circular disk-shaped polymer film 4 is attached to a rotationally symmetrical support body 6, which is provided, for example, on its inner wall with an annular recess which extends as far as the end faces of the support bodies 6 facing away from the polymer film 4.
  • a likewise annular electrode 88 is inserted into this recess and fixed with a holding flange 66 fastened to the support body 6.
  • the electrodes 88 are, for example, metallic rings whose wall thickness can be less than 1 mm.
  • the electrodes 88 consist, for example, of stainless steel or brass, which is provided with a platinum protective layer, for example, to protect it from the corrosive properties of the surrounding medium. From the electrodes 88 lead 82 lead through grooves 68 of the support body 6 to its cylindrical outer edge.
  • the polymer film 4 is therefore no longer coated with electrodes.
  • the ultrasonic sensor 24 can also be significantly reduced in its linear dimensions, since in this embodiment the electrodes 88 can also be in the immediate vicinity of the focus of an ultrasonic shock wave, without the risk of the electrodes being destroyed 88 exists.
  • Such miniaturization of the ultrasound sensor 24 has the advantage that the coupling capacitances of the piezoelectrically active area 42 to the electrodes 88 are increased by reducing the mutual distance and thus the sensitivity of the ultrasound sensor 24 is increased.
  • the ultrasonic sensor 24 can also be provided with a ground electrode according to FIG. 4 or with cover plates according to FIG.
  • a polymer film 4 is located between two movably arranged electrodes 14 of a high-voltage source 16 lying opposite one another.
  • the electrodes 14 lying opposite one another are applied to the polymer film 4 in a surface area of the polymer film 4 that is assigned to the piezoelectrically activated partial area 42.
  • the defined partial area 42 of the polymer film 4 is then polarized and piezoelectrically activated by applying the high voltage 16.
  • the further process steps required to activate the polymer film 4 are described, for example, in the publication "J.Acoust.Soc. Am.” Vol. 69, No. 3, March 1981 on page 854.
  • the electrodes 14 can also be provided on their end faces with an electrically conductive elastic stamp 18, which consists, for example, of a conductive polymer or of conductive rubber.
  • the polymer film 4 can then be firmly clamped between these elastic stamps 18 without the risk of mechanical destruction of the polymer film 4.
  • the punches 18 touch the polymer film 4 over their entire end face. This measure can thus increase the homogeneity in the piezoelectric properties of the polarized region 42 of the polymer film 4.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Transducers For Ultrasonic Waves (AREA)
EP86117065A 1985-12-20 1986-12-08 Sonde ultrasonique Expired - Lifetime EP0227985B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE3545382 1985-12-20
DE3545382 1985-12-20

Publications (3)

Publication Number Publication Date
EP0227985A2 true EP0227985A2 (fr) 1987-07-08
EP0227985A3 EP0227985A3 (en) 1987-10-21
EP0227985B1 EP0227985B1 (fr) 1991-03-06

Family

ID=6289135

Family Applications (1)

Application Number Title Priority Date Filing Date
EP86117065A Expired - Lifetime EP0227985B1 (fr) 1985-12-20 1986-12-08 Sonde ultrasonique

Country Status (4)

Country Link
US (1) US4734611A (fr)
EP (1) EP0227985B1 (fr)
JP (1) JP2591737B2 (fr)
DE (1) DE3677921D1 (fr)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0332916A1 (fr) * 1988-03-10 1989-09-20 Siemens Aktiengesellschaft Capteur à ultrasons
EP0381796A1 (fr) * 1989-02-10 1990-08-16 Siemens Aktiengesellschaft Capteur ultrasonore
EP0418663A1 (fr) * 1989-09-22 1991-03-27 Richard Wolf GmbH Hydrophone à membrane piezoélectrique
EP0472085A1 (fr) * 1990-08-24 1992-02-26 Siemens Aktiengesellschaft Capteur d'ultrason

Families Citing this family (19)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4813402A (en) * 1986-02-19 1989-03-21 Siemens Aktiengesellschaft Coupling member for a shock wave therapy device
EP0255636B1 (fr) * 1986-07-30 1990-04-25 Siemens Aktiengesellschaft Capteur pour des ondes de chocs acoustiques
DE8622104U1 (de) * 1986-08-18 1987-12-17 Siemens AG, 1000 Berlin und 8000 München Vorrichtung zum Zertrümmern von Konkrementen
EP0256438A1 (fr) * 1986-08-18 1988-02-24 Siemens Aktiengesellschaft Détecteur pour enregistrer les impulsions d'ondes de choc
US4924131A (en) * 1987-10-14 1990-05-08 Fujikura Ltd. Piezo-electric acceleration sensor
US4835435A (en) * 1988-01-19 1989-05-30 Hewlett-Packard Company Simple, sensitive, frequency-tuned drop detector
US5072426A (en) * 1991-02-08 1991-12-10 Sonic Technologies Self-monitoring shock wave hydrophone
US5381386A (en) * 1993-05-19 1995-01-10 Hewlett-Packard Company Membrane hydrophone
US5406951A (en) * 1993-10-15 1995-04-18 Ten Hoff; Harm Intra-luminal ultrasonic instrument
US5479377A (en) * 1994-12-19 1995-12-26 Lum; Paul Membrane-supported electronics for a hydrophone
US6012779A (en) * 1997-02-04 2000-01-11 Lunar Corporation Thin film acoustic array
US20050245824A1 (en) * 2004-04-20 2005-11-03 Acoustic Marketing Research, A Colorado Corporation, D/B/A Sonora Medical Systems, Inc. High-intensity focused-ultrasound hydrophone
DE102005044677A1 (de) * 2005-09-19 2007-03-29 Abb Patent Gmbh Magnetisch-induktiver Durchflussmesser mit einer Erdungsscheibe
DE102006004874A1 (de) * 2006-02-03 2007-08-09 Robert Bosch Gmbh Sensorvorrichtung für Fahrzeuge
US7859171B2 (en) * 2006-10-10 2010-12-28 Micallef Joseph A Piezoelectric ultracapacitor
US7755257B2 (en) * 2007-09-03 2010-07-13 Micallef Joseph A Piezoelectric ultracapacitor
US8569930B2 (en) * 2009-05-11 2013-10-29 Nec Corporation Piezoelectric actuator and audio components
JP6263902B2 (ja) * 2013-08-21 2018-01-24 株式会社村田製作所 超音波発生装置
US9389139B2 (en) * 2014-07-15 2016-07-12 The United States Of America As Represented By The Secretary Of The Army Method for studying the evolution of damage in cylinders subjected to internal radial explosion

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US4048526A (en) * 1975-08-08 1977-09-13 Minnesota Mining And Manufacturing Company Kinetic sensor employing polymeric piezoelectric material
US4079437A (en) * 1976-04-30 1978-03-14 Minnesota Mining And Manufacturing Machine and method for poling films of pyroelectric and piezoelectric material
AT375466B (de) * 1977-07-27 1984-08-10 List Hans Messwertaufnehmer mit einem piezoelektrischen messelement
JPS572196A (en) * 1980-06-04 1982-01-07 Pioneer Electronic Corp Pickup cartridge of movable coil type
US4433400A (en) * 1980-11-24 1984-02-21 The United States Of America As Represented By The Department Of Health And Human Services Acoustically transparent hydrophone probe
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Title
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ULTRASONICS, Mai 1980, Seiten 123-126; IPC Business Press, Guilford, (GB) K.C. SCHOTTON et al.: "A pvdf membrane hydrophone for operation in the range 0.5 MHz to 15 MHz." *
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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0332916A1 (fr) * 1988-03-10 1989-09-20 Siemens Aktiengesellschaft Capteur à ultrasons
EP0381796A1 (fr) * 1989-02-10 1990-08-16 Siemens Aktiengesellschaft Capteur ultrasonore
US5056069A (en) * 1989-02-10 1991-10-08 Siemens Aktiengesellschaft Ultrasonic sensor
EP0418663A1 (fr) * 1989-09-22 1991-03-27 Richard Wolf GmbH Hydrophone à membrane piezoélectrique
EP0472085A1 (fr) * 1990-08-24 1992-02-26 Siemens Aktiengesellschaft Capteur d'ultrason

Also Published As

Publication number Publication date
EP0227985A3 (en) 1987-10-21
JPS62154900A (ja) 1987-07-09
JP2591737B2 (ja) 1997-03-19
DE3677921D1 (de) 1991-04-11
EP0227985B1 (fr) 1991-03-06
US4734611A (en) 1988-03-29

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