WO1993007970A1 - Capteurs - Google Patents

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Publication number
WO1993007970A1
WO1993007970A1 PCT/GB1992/001841 GB9201841W WO9307970A1 WO 1993007970 A1 WO1993007970 A1 WO 1993007970A1 GB 9201841 W GB9201841 W GB 9201841W WO 9307970 A1 WO9307970 A1 WO 9307970A1
Authority
WO
WIPO (PCT)
Prior art keywords
thermal
electrode
acoustic sensor
junction
electrodes
Prior art date
Application number
PCT/GB1992/001841
Other languages
English (en)
Inventor
David Robert Bacon
Roy Charles Preston
Original Assignee
The Secretary Of State For Trade And Industry In Her Britannic Majesty's Government Of The United Kingdom Of Great Britain And Northern Ireland
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 The Secretary Of State For Trade And Industry In Her Britannic Majesty's Government Of The United Kingdom Of Great Britain And Northern Ireland filed Critical The Secretary Of State For Trade And Industry In Her Britannic Majesty's Government Of The United Kingdom Of Great Britain And Northern Ireland
Publication of WO1993007970A1 publication Critical patent/WO1993007970A1/fr

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01H—MEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC OR INFRASONIC WAVES
    • G01H11/00—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by detecting changes in electric or magnetic properties
    • G01H11/06—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by detecting changes in electric or magnetic properties by electric means
    • G01H11/08—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by detecting changes in electric or magnetic properties by electric means using piezoelectric devices

Definitions

  • the present invention relates to sensors, and is particularly concerned with sensors for use in the calibration of the acoustic % output of medical ultrasound equipment used for diagnosis or therapy.
  • Ultrasound has many medical uses, including scanning to 5 determine various internal body conditions such as the size and condition of a foetus in a womb, and for heat treatment, for example in the treatment of cancer. Ultrasound does however have a heating effect when it passes through the body and this effect can be significant, particularly when, as in many medical applications, a 10 focussed beam is used.
  • thermocouple 15 is positioned in a gel having the characteristics of tissue, and an ultrasound beam from the equipment under test is focussed on the thermocouple.
  • thermoelectric effect is small and only becomes significant when the beam is focussed on the thermocouple. This makes it very difficult to 20 align the thermocouple and the beam.
  • conventional thin wire thermocouples present a significant obstacle to ultrasound beams, giving rise to relative movement between the wires and the surrounding medium causing viscous heating effects which distort the test results. There is therefore a requirement for a thermocouple which allows 25 for easier alignment and which gives rise to.minimal perturbation of the ultrasound beam.
  • a thermal and acoustic sensor includes a first electrode of a first material and a second electrode of a second material, the electrodes meeting to form one junction of a 30 thermocouple, the junction being separated from a tip of a third ⁇ electrode by a thickness of a layer of piezoelectric material.
  • the third electrode might be of any convenient material which could be one of the first or second materials.
  • the piezoelectric layer might be a plastic material such as, for example, polyvinylidene fluoride or a copolymer of difluoroethylene with trifluoroethylene or tetrafluoroethylene. These materials can be obtained in the form of thin films, a film typically having a thickness of 2 microns.
  • Suitable materials are silver or gold for the first material and nickel for the second material. They might conveniently be positioned on surfaces of the piezoelectric material in paint form by painting or spraying, using vapour deposition, or otherwise.
  • a device for use in the calibration of acoustic wave equipment consists of a thin piezoelectric film having thin gold and nickel electrodes forming a junction of a thermocouple on a first surface thereof and a thin gold electrode with its tip underlying the junction on a second surface thereof.
  • thermocouple When the electrodes are connected to circuits to form respectively a thermocouple and a pressure sensor and the device is positioned in a test medium through which is passed a focussed beam from an acoustic generator the output of the thermocouple will be negligible if it lies outside the focussed beam whilst the pressure sensor, whilst giving maximum output * when lying at the focal point of the beam, will give some output whenever the beam impinges on the piezoelectric film.
  • Figure 1 is a plan view of a thermal and acoustic sensor according to the invention
  • Figure 2 is an elevation, in section along line II-II of Figure 1, of a detail of the sensor
  • Figure 3 s an elevation, in section, of a sensor being used to assist in the focussing of an acoustic wave generator.
  • a sensor 10 ( Figure 1) consists of a thin layer 11 which might be a 5 micron thick film of piezoelectric material such as, for example, polyvinylidene fluoride, on a first surface 20 (see Figure 2) of which are positioned a first electrode 12 of a first material such as, for example, gold and a second electrode 13 of a second material such as, for example, nickel.
  • the electrodes are joined together at a junction 1 to form one junction of a thermocouple.
  • the electrodes f( 12, 13. terminate at terminals 16, 17 respectively.
  • a third electrode 18, of any suitable material which might, for example, be the same as that of one of the first two electrodes 12, 13.
  • the third electrode 18 has a tip 19 lying such that the same normal to the layer 11 passes through both the junction 15 and the tip 1 (see 10 particularly Figure 2).
  • the electrode 18 terminates at a terminal 23-
  • the electrodes 12, 13, 18 can be positioned on the layer 11 by any convenient means, such as, for example, by painting or spraying, by vacuum deposition, or otherwise and should be a thin as possible, though in practice they will usually have to be thicker than 0.3 15 microns.
  • the terminals 16, 17 are used to connect the first and second electrodes 12, 13 into a first circuit, shown generally at 30 in Figure 1, such that the system acts as a thermocouple sensitive to the temperature at the junction 15.
  • the circuit 30 includes 20 temperature indicating means 31-
  • the terminal 23 of the third electrode and one of the terminals 16, 17, shown in Figure 1 as terminal 16 of the first electrode 12, are connected to a second circuit, shown generally at 40 in Figure 1, which includes a pressure indicator 4l such that pressure variations affecting the film in the 25 region of the junctions 19. 15 can, as a result of the piezoelectric effect, be measured.
  • a sensor 10 is embedded in a bulk 0 ( Figure 3) of gel having 30 characteristics simulating those of tissue.
  • An acoustic wave generator 51 is positioned such that an ultrasonic beam 52 issuing
  • ⁇ focal point will fall neither on the junction 15 nor on the layer 11, 35 and as a result the temperature indicator 30 will show no change as a result of switching on the beam 5 .
  • the beam 2 impinges on the layer 11 there will be a response from the pressur indicator l.
  • the nearer the focal point 53 is to the layer 11 the greater will be the response of the pressure indicator l, allowing the beam 2 to be focussed to position the focal point 53 on the laye 11, and the nearer the focal point 53 to the disposition of junction 15 and tip 19 the greater the response of the pressure indicator 4l, allowing the position of the focal point 53 on the layer 11 to be moved until it lies on this disposition, and hence on the junction 15, at which stage the temperature indicator 31 will respond and calibration can start.

Abstract

Un capteur thermique et acoustique comprend une jonction (15) d'un thermocouple formé par une première et une seconde électrode (12, 13) composées de différents matériaux et situées sur une surface (20) d'un matériau piézoélectrique, et comprend une pointe (19) d'une troisième électrode (18) placée sous la jonction (15), sur l'autre surface (21) du matériau piézoélectrique. Lors de l'utilisation du capteur, les première et seconde électrodes (12, 13) sont connectées en un circuit formant un thermocouple et comprenant un indicateur de température (31), la troisième électrode (18) et la première ou la seconde électrode (12, 13) étant connectées à un transducteur (41) de pression pour former un capteur de pression.
PCT/GB1992/001841 1991-10-25 1992-10-09 Capteurs WO1993007970A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB919122704A GB9122704D0 (en) 1991-10-25 1991-10-25 Sensors
GB9122704.1 1991-10-25

Publications (1)

Publication Number Publication Date
WO1993007970A1 true WO1993007970A1 (fr) 1993-04-29

Family

ID=10703544

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB1992/001841 WO1993007970A1 (fr) 1991-10-25 1992-10-09 Capteurs

Country Status (2)

Country Link
GB (1) GB9122704D0 (fr)
WO (1) WO1993007970A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102005062813A1 (de) * 2005-12-27 2007-07-05 Vega Grieshaber Kg Füllstandmessanordnung mit einer Sicherheitsabschaltung bei hohen Temperaturen
CN102724615A (zh) * 2011-03-29 2012-10-10 清华大学 热致发声装置及电子装置

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0256202A2 (fr) * 1986-08-18 1988-02-24 Siemens Aktiengesellschaft Corps de couplage pour un dispositif thérapeutique utilisant des ondes de choc
FR2654210A1 (fr) * 1989-11-08 1991-05-10 Saint Louis Inst Dispositif de mesure pour la determination d'une grandeur physique.

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0256202A2 (fr) * 1986-08-18 1988-02-24 Siemens Aktiengesellschaft Corps de couplage pour un dispositif thérapeutique utilisant des ondes de choc
FR2654210A1 (fr) * 1989-11-08 1991-05-10 Saint Louis Inst Dispositif de mesure pour la determination d'une grandeur physique.

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102005062813A1 (de) * 2005-12-27 2007-07-05 Vega Grieshaber Kg Füllstandmessanordnung mit einer Sicherheitsabschaltung bei hohen Temperaturen
DE102005062813B4 (de) * 2005-12-27 2009-11-26 Vega Grieshaber Kg Füllstandmessanordnung mit einer Sicherheitsabschaltung bei hohen Temperaturen
CN102724615A (zh) * 2011-03-29 2012-10-10 清华大学 热致发声装置及电子装置

Also Published As

Publication number Publication date
GB9122704D0 (en) 1991-12-11

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