EP2595763A2 - Method and device for generating ultrasounds implementing cmuts, and method and system for medical imaging. - Google Patents
Method and device for generating ultrasounds implementing cmuts, and method and system for medical imaging.Info
- Publication number
- EP2595763A2 EP2595763A2 EP11754696.0A EP11754696A EP2595763A2 EP 2595763 A2 EP2595763 A2 EP 2595763A2 EP 11754696 A EP11754696 A EP 11754696A EP 2595763 A2 EP2595763 A2 EP 2595763A2
- Authority
- EP
- European Patent Office
- Prior art keywords
- frequency
- micro
- membrane
- capacitive transducer
- transducer
- 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.)
- Withdrawn
Links
Classifications
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B8/00—Diagnosis using ultrasonic, sonic or infrasonic waves
- A61B8/44—Constructional features of the ultrasonic, sonic or infrasonic diagnostic device
- A61B8/4483—Constructional features of the ultrasonic, sonic or infrasonic diagnostic device characterised by features of the ultrasound transducer
- A61B8/4494—Constructional features of the ultrasonic, sonic or infrasonic diagnostic device characterised by features of the ultrasound transducer characterised by the arrangement of the transducer elements
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B8/00—Diagnosis using ultrasonic, sonic or infrasonic waves
- A61B8/44—Constructional features of the ultrasonic, sonic or infrasonic diagnostic device
- A61B8/4483—Constructional features of the ultrasonic, sonic or infrasonic diagnostic device characterised by features of the ultrasound transducer
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B8/00—Diagnosis using ultrasonic, sonic or infrasonic waves
- A61B8/13—Tomography
- A61B8/14—Echo-tomography
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B8/00—Diagnosis using ultrasonic, sonic or infrasonic waves
- A61B8/13—Tomography
- A61B8/14—Echo-tomography
- A61B8/145—Echo-tomography characterised by scanning multiple planes
-
- 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
- B06B1/0292—Electrostatic transducers, e.g. electret-type
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B90/00—Instruments, implements or accessories specially adapted for surgery or diagnosis and not covered by any of the groups A61B1/00 - A61B50/00, e.g. for luxation treatment or for protecting wound edges
- A61B90/36—Image-producing devices or illumination devices not otherwise provided for
- A61B90/37—Surgical systems with images on a monitor during operation
- A61B2090/378—Surgical systems with images on a monitor during operation using ultrasound
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
- A61N7/00—Ultrasound therapy
Definitions
- the present invention relates to a method of generating ultrasound using micro-machined capacitive transducers (cMUT). It also relates to an ultrasound generating device implementing such a method. Finally, it relates to a method and a medical imaging system implementing cMUTs.
- the field of the invention is the field of ultrasound generation using descMUT.
- a cMUT transducer is made up of several hundred or even a few thousand mechanically insulated "micromembranes" capable of being actuated by electrostatic forces. They are called cMUT for Capacitive Micromachined UltrasonicTransducers.
- Each cMUT consists of a rear electrode formed by a semiconductor material (generally doped polysilicon), a vacuum cavity of height H gap , a membrane made of microelectronic material on which an electrode rests, the membrane / electrode assembly constituting the "mobile" part of the device.
- a semiconductor material generally doped polysilicon
- the material used for the membrane is often silicon nitride but it is highly dependent on the manufacturing technology of the device itself.
- Other materials such as doped polysilicon ("wafer bonding" process), a metal or a polymer could be used.
- CMUTs are now commonly used in the field of medical imaging to excite an organ or tissue of a human or animal subject.
- the use of micro-machined capacitive transducers in ultrasonic medical imaging is based on the same protocols for use as piezoelectric devices.
- the cMUT transducer is biased with a DC voltage and the sending of a pressure wave is by means of a broadband excitation which covers the entire passband of the transducer.
- the central frequency of these devices that is to say the resonance frequency, is defined by the membrane / fluid couple which acts as a mass / spring system where the elasticity depends solely on the properties of the membrane and of the mass of the fluid. This The effect of mass is also dependent on the effects of mutual interactions between membranes which have the consequence of creating cutoff frequencies in the bandwidth of the transducer.
- low frequency ultrasound for example ultrasound of frequencies less than or equal to 2 MHz
- membranes with low mechanical rigidity that can be obtained either by increasing their width, by decreasing their thickness or by using Low Young's modulus materials.
- Low resonance frequency devices are generally not functional. Indeed, their mechanical rigidity being relatively low, the membranes undergo the pressure of the outside air and thus deform several tens of nanometers, or a hundred. Deformation can lead to blockage of the membrane at the bottom of the cavity, thus rendering the device unusable.
- it is possible to increase the height of the cavity to maintain a "free" space between the membrane and the rear of the cavity but this leads to greatly increase the supply voltages necessary for controlling the cMUTs.
- Another object of the present invention is to provide a method and a device for generating ultrasound with at least one cMUT transducer easier to manufacture, less expensive and operating with a supply voltage is more accessible and acceptable for low voltage power supplies, while achieving satisfactory working pressure levels.
- the invention proposes to achieve the aforementioned goals by a method of generating ultrasound in a given fluid by using at least one micro-machined capacitive transducer (cMUT) comprising a membrane and having a predetermined resonant frequency defined by the membrane pair fluid, characterized in that said at least one transducer is powered with a frequency excitation signal less than said central frequency.
- cMUT micro-machined capacitive transducer
- the frequency f of the ultrasound wave generated is less than the resonance frequency f 0 and more particularly equal to the frequency of the excitation signal.
- the invention relates to transducers whose membranes have the same architecture so that they all have the same and a single resonant frequency.
- the cMUT transducer comprises at least one micro-machined capacitive cell (cMUT), also called “micro-membrane”, mechanically insulated and capable of being actuated by electrostatic forces.
- cMUT micro-machined capacitive cell
- the inventors of the present invention have surprisingly found, on the basis of experimental results obtained in air and in water, that a micro-machined capacitive transducer is capable of producing high amplitude displacements, well below its membrane-fluid interaction frequency. Unlike piezoelectric systems that exhibit high mechanical stiffness, it is not necessary for the cMUT transducer membrane to resonate to produce displacements large enough to produce significant pressure levels.
- each membrane behaves as an "ideal" source point of pressure, so that only one parameter conditions the amplitude of the emitted ultrasonic pressure: the number of membranes cMUTss put into play on a bar element. In other words: with an equivalent surface area, it is the coverage rate and the average amplitude of the displacements that define the ultrasonic intensity radiated.
- the frequency of the excitation signal is advantageously less than 20% or even 50% lower than the center frequency of the at least one micro-machined capacitive transducer. Even more particularly the inventors have noticed that the frequency f of the excitation signal f 0 may be less than half the resonance frequency, and more particularly 0.2f 0 ⁇ f ⁇ 0.5f 0 , and more particularly 0.3f 0 ⁇ f ⁇ 0.5f 0 , 0.4f 0 ⁇ f ⁇ 0.5f 0 .
- the inventors were able to generate, with a transducer cMUTriesentant one resonance frequency f 0, ultrasound at much lower frequencies f 0, typically below f 0/2.
- the property exploited for this generation mode is the capacity for cMUTs technologies, to locally produce shifts of several tens or even a hundred nanometers that do not require the resonance of the membranes.
- This arrangement then makes it possible to generate low frequency ultrasound waves in a wide frequency band, irrespective of the geometry and the topology of the diaphragm. For example, considering a transducer whose resonant frequency is 4 MHz, it will be possible with this same device to emit an ultrasound wave at 1 MHz, such as at 1.5 MHz without having to design a device with several resonant frequencies.
- the pressure emitted at the focal point is 1 MPa and at 1.5 MHz it is 1.5 MPa.
- the useful pressure levels obtained for a radiating surface equivalent to 100 mm 2 at an excitation frequency of 500 kHz are greater than or equal to:
- the at least one micro-machined capacitive transducer may be designed so that its central frequency is greater than or equal to 4 MHz and with a gap height of between 100 nm and 300 nm, at least one transducer being excited with a frequency excitation signal less than 2 MHz to generate ultrasound frequencies between 200 kHz and 2 MHz.
- the supply voltage of the at least one micro-machined capacitive transducer may be between IV and 150 V. These voltages are lower voltages than those used in the state of the art. to supply cMUTs transducers for the generation of low frequency ultrasound, especially frequencies below 2 MHz in water and 1 MHz in air.
- the method according to the invention can be used for the generation of ultrasound frequencies below 1 MHz in a gaseous medium with an excitation signal of between 200 kHz and 1 MHz.
- the supply voltage can be between 50 and
- the method according to the invention can also be used for the generation of ultrasound frequencies below 2 MHz in a liquid or aqueous medium with an excitation signal of between 200 kHz and 2 MHz.
- the supply voltage can be between the first and the second
- the method according to the invention allows the generation of ultrasound:
- cMUT micro-machined capacitive transducer
- said method comprising a supply of said micro-machined capacitive transducer with a supply voltage of between IV and 150 V with a frequency of between 200 kHz and 1 M Hz in the gaseous medium and 200 kHz and 1 MHz in the aqueous medium.
- a method for medical imaging of a tissue or an organ of a human or animal subject comprising the steps of:
- the device according to the invention may comprise at least one micro-machined capacitive transducer (cMUT) designed so that it has:
- a resonance frequency or center frequency greater than or equal to 4MHz in the water, and a gap height of between 100 nm and 300 nm.
- the transducer is supplied with a supply voltage of between IV and 150 V delivered by supply means.
- the micro-machined capacitive transducer when the device according to the invention is used to generate ultrasound in an aqueous or liquid medium, the micro-machined capacitive transducer has:
- the micromachined capacitive transducer when the device according to the invention is used to generate ultrasound in an aqueous or liquid medium, the micromachined capacitive transducer has:
- the micro-machined capacitive transducer when the device according to the invention is used to generate ultrasound in an aqueous or liquid medium, the micro-machined capacitive transducer has:
- the micro-machined capacitive transducer when the device according to the invention is used to generate ultrasound in a gaseous medium, the micro-machined capacitive transducer has:
- the micro-machined capacitive transducer when the device according to the invention is used to generate ultrasound in a gaseous medium, the micro-machined capacitive transducer has:
- the micro-machined capacitive transducer when the device according to the invention is used to generate ultrasound in a gaseous medium, the micro-machined capacitive transducer has:
- the device according to the invention can comprise: a first power supply module intended to supply the micro-machined capacitive transducer with a frequency excitation signal lower than said central frequency,
- a second power supply module intended to supply the micro-machined capacitive transducer with a frequency excitation signal centered around said central frequency
- selection means for selecting one of said power supply modules so that said micro-machined capacitive transducer is powered by only one of said power supply modules at a time.
- the device according to the invention can comprise:
- a first power supply module for supplying said at least one micro-machined capacitive transducer with a frequency excitation signal less than said central frequency
- a second power supply module for supplying said at least one second micro-machined capacitive transducer with a frequency excitation signal centered around said central frequency.
- an ultrasound medical imaging system comprising:
- At least one ultrasound generating device for exciting a tissue or an organ of a human or animal subject
- imaging means for producing images of said tissue or organ when said organ is excited.
- the imaging means may comprise MRI imaging means or any other imaging means used in the field of ultrasound medical imaging.
- Figure 1 is a schematic representation of an exemplary micromachined capacitive transducer comprising a plurality of elementary cells cMUTs;
- Figure 2 is a schematic representation of a cMUT elementary cell in top view and in cross-sectional view
- FIGS. 3 to 5 are graphs representing simulation results in water of a cMUT transducer for different gap heights (or cavity heights) as a function of membrane width, membrane height, voltage power supply and the center frequency of the cMUT transducer, for a constant Young's modulus;
- Figures 6 to 8 are graphs showing simulation results in water of a cMUT transducer for different Young's moduli as a function of membrane width, membrane height, supply voltage and the central frequency of the cMUT transducer, for a constant gap height (or cavity height);
- FIGS. 9 to 11 are graphs representing simulation results in the air of a cMUT transducer for different gap heights (or cavity heights) as a function of membrane width, membrane height, voltage power supply and the center frequency of the cMUT transducer, for a constant Young's modulus;
- Figures 12 to 14 are graphs showing air simulation results of a cMUT transducer for different Young's moduli as a function of membrane width, membrane height, supply voltage and the central frequency of the cMUT transducer, for a constant gap height (or cavity height);
- FIG. 15 is a group of graphs representing values of the pressure field radiated in a gaseous medium by an excited cMUT transducer, according to the invention, in a forced elastic regime
- FIG. 16 is a group of graphs representing values of the pressure field radiated in a liquid medium by an excited cMUT transducer, according to the invention, in a forced elastic regime
- FIG. 17 is a schematic representation of an example of a device according to the invention.
- FIGs 18 and 19 are representations of two embodiments of a dual-function device according to the invention.
- a cMUT transducer is made up of several hundred or even a few thousand mechanically insulated "micromembranes" capable of being actuated by electrostatic forces. They are called cMUTs, Capacitive MicromachinedUltrasonicTransducers. These membranes are simple capacitive microphones whose operating principle is similar to that of the devices used in audio for applications in the air. However, there are significant differences since the cavities on which the membranes are based are at zero pressure and isolated from the outside, thus allowing use in a fluid medium.
- Figure 1 is a schematic representation of an example of micro-machined capacitive transducer 100.
- the cMUT 100 transducer comprises, in a nonlimiting manner, 24 elementary cells 102, or micromembrane, of square geometry arranged in 6 rows of 4.
- the width of the transducer 100 is 0.165mm.
- the cMUT transducer also includes feed lines 104 of each of the cells.
- Figure 2 is a schematic representation of an elementary cell cMUT 102 viewed from above and in section.
- the elementary cell 102 comprises:
- a rear electrode 202 formed by a semiconductor material, for example doped polysilicon, of thickness 500 nm for example; a void cavity 204 of given height called gap gap height, of a value of 200 nm for example;
- a membrane 206 made of microelectronic material for example with a thickness of 450 nm;
- a front electrode 208 also called “mobile” electrode thickness 350nm for example.
- the material used for the membrane is, for example silicon nitride, but it depends strongly on the technique of manufacturing the device. Other materials such as doped polysilicon (wafer bonding), a metal or a polymer could be used.
- the movable electrode 208 may be aluminum, or any other type of conductive material compatible with the use. In the same way, the materials used to make the movable electrode 208 differ only in their Young's modulus.
- the metallization on the front face of each membrane can be 100% of the surface up to a few percent. It is often accepted that 50% of metallized surface is a good compromise stiffness / mass and efficiency of the electrostatic forces. It is important to specify that, from a mechanical point of view, changing the thickness of the membranes or the Young's modulus of materials or the metallization rate is defined by a global parameter called bending stiffness, which is the only parameter useful mechanics of these microsystems.
- the resonant frequency depends on
- the collapse tension depends on:
- the collapse tension Vc increases if flexural stiffness increases and / or the surface increases.
- the present invention proposes, in the present example, compromises or interesting areas of compromise, constituting "technological corridors" of interest for working at low frequency where the membrane of each of the cMUTs cells is used in forced mode and not in "resonant” mode. ". In the air, this corresponds to the ability to generate significant amplitude displacements for frequencies below 1 MHz while the resonant frequency is much higher. In water, the low frequency is below 2 MHz. This then corresponds to the ability to generate significant shifts in low frequency while the resonance is well above 2 MHz, typically above 4 MHz.
- the invention proposes to produce transducers that can generate low-frequency ultrasound in air and in water by relying on lower cost manufacturing processes, less complex than the devices of the state of the art.
- the technique in this case surface micromachining techniques over very large widths or using particularly flexible materials.
- FIGS. 3 to 5 are graphs representing simulation results in water of a cMUT transducer for different gap heights (or cavity height) as a function of membrane width, membrane height, the supply voltage and center frequency of the cMUT transducer, for a constant Young's modulus of 200GPa.
- FIGS. 3 to 5 are identical in FIGS. 3 to 5:
- the dotted lines correspond to the resonance frequency level curves in MHz
- the spaced dotted lines correspond to the level curves of the initial deflection in nm.
- the marked gray area (2) corresponds to the values of the technological compromises for generating ultrasound of frequency less than or equal to 2M Hz with central frequency transducers greater than or equal to 4M Hz.
- the marked area (2) for the points of coordinates ends [width membrane, membrane thickness] [10 pm, 100 nm], [10 pm, 400 nm ], [30 ⁇ m, 600 nm], [30 ⁇ m, 1000 nm].
- the marked zone (2) has at its ends the points of coordinates [membrane width, membrane thickness]: [10 ⁇ m, 200 nm], [15 ⁇ m, 200 nm] , [25 ⁇ m, 400 nm], [35 ⁇ m, 1000 nm].
- the marked area (2) has at its ends the points of coordinates [membrane width, membrane thickness]: [15 ⁇ m, 300 nm], [25 ⁇ m, 300 nm] , [30 ⁇ m, 600 nm], [30 ⁇ m, 800 nm].
- Figures 9 to 11 are graphs showing simulation results obtained in air under the same conditions as for Figures 3 to 5.
- FIGS. 9 to 11 are identical in FIGS. 9 to 11:
- the dashed lines correspond to the resonance frequency level curves in M Hz
- the spaced dotted lines correspond to the level curves of the initial deflection in nm.
- the marked shaded area (2) corresponds to the values of the technological compromises for generating ultrasound of frequency less than or equal to 1 M Hz with central frequency transducers greater than or equal to 4M Hz.
- the marked area (2) has at its ends the points of coordinates [membrane width, membrane thickness]: [10 ⁇ m, 100 nm], [15 ⁇ m, 100 nm] , [35 ⁇ m, 700 nm], [25 ⁇ m, 1000 nm].
- the marked area (2) has the ends of the points of coordinates [width membrane, membrane thickness] [10 pm, 200 nm], [15 pm, 200 nm ], [40 ⁇ m, 600 nm], [35 ⁇ m, 1000 nm].
- the marked area (2) has at its ends the points of coordinates [membrane width, membrane thickness]: [15 ⁇ m, 300 nm], [25 ⁇ m, 300 nm] , [45 ⁇ m, 600 nm], [40 ⁇ m, 700 nm].
- FIGS. 6 to 8 are graphs showing simulation results, in water, of a cMUT transducer for different Young's moduli as a function of membrane width, membrane height, supply voltage and the central frequency of the cMUT transducer, for a constant gap height (or cavity height) of 200 nm.
- the dashed lines correspond to the resonance frequency level curves in M Hz
- the spaced dotted lines correspond to the level curves of the initial deflection in nm.
- the marked shaded area (2) corresponds to the values of the technological compromises for generating ultrasound of frequency less than or equal to 2M Hz with central frequency transducers greater than or equal to 4M Hz.
- the marked area (2) has at its ends the points of coordinates: [membrane width, membrane thickness]: [10 ⁇ m, 200 nm], [15 ⁇ m, 200 nm] , [30 ⁇ m, 1000 nm], [25 ⁇ m, 1000 nm].
- the marked area (2) has at its ends the points of coordinates [membrane width, membrane thickness]: [10 ⁇ m, 200 nm], [15 ⁇ m, 200 nm], [25 ⁇ m, 400 nm], [35 ⁇ m, 1000 nm].
- the marked area (2) has at its ends the points of coordinates [membrane width, membrane thickness]: [10 ⁇ m, 200 nm], [20 ⁇ m, 200 nm], [35 ⁇ m, 600 nm], [35 ⁇ m, 1000 nm].
- FIGS. 12 to 14 are graphs representing simulation results obtained, in air, under the same conditions as for FIGS. 6 to 8.
- the dotted lines correspond to the resonance frequency level curves in MHz
- the marked shaded area (2) corresponds to the values of the technological compromises for generating ultrasound with a frequency of less than or equal to 1 MHz with central frequency transducers greater than or equal to 4 MHz.
- the marked area (2) has at its ends the points of coordinates [membrane width, membrane thickness]: [10 ⁇ m, 200 nm], [15 ⁇ m, 200 nm], [40 ⁇ m, 1000 nm], [25 ⁇ m, 1000 nm].
- the marked area (2) has the ends of the coordinate points [width membrane, membrane thickness]: [10 ⁇ m, 200 nm], [15 ⁇ m, 200 nm], [40 ⁇ m, 600 nm], [35 ⁇ m, 1000 nm].
- the marked area (2) has at its ends the points of coordinates: [membrane width, membrane thickness]: [10 ⁇ m, 200 nm], [20 ⁇ m, 200 nm] , [35 ⁇ m, 500 nm], [30 ⁇ m, 1000 nm].
- FIG. 15 is a group of graphs representing values of the pressure field radiated in the air by an excited cMUT transducer, according to the invention, in a forced elastic regime.
- a square geometry transducer size 30x30 mm 2 having a 2D array of square membranes 20x20 pm 2 with a periodicity of 30 pm, a 45% coverage and therefore an average surface area of 405 mm 2 was used.
- FIG. 15 shows that the emitted pressure field perfectly follows the excitation frequency initially applied to the cMUT transducer.
- the pressure values achieved are comparable to the values necessary for operating these devices in the air.
- the standards of transmission in the air specify that a reference value of the SPL (Sound Pressure Level) is 20pPa at a distance of 30 cm and that a data transmission application requires a pressure of order 100-120 dB that is to say between 2 and 20 Pa.
- the emitted pressure field perfectly follows the excitation frequency initially applied to the cMUT transducer.
- the pressure values achieved are comparable to the values needed to operate these devices in the water.
- the invention enables to replace traditional materials ⁇ piezo electric by silicon components on which are engraved thousands of microcomponents capacitive able to vibrate.
- This technology cMUT Capacitive Micromachined UltrasonicTransducers
- cMUTs membranes, more elastic than initial, are able to deform over amplitudes of a few hundred nanometers for excitation voltages lower than 100 Volts.
- the invention can be used to produce low frequency probes (100 kHz - 2 MHz), based on cMUTs technologies.
- the cMUTs are used in operating regimes different from those used in medical imaging where the emission is a broadband excitation (greater than 20 MHz) and whose amplitude is typically 150 volts.
- the invention makes it possible to use them in quasi-static mode (low band excitation ⁇ 2 MHz) so as to impose on the membranes displacements of high amplitude, close to the cavity height.
- the size of the transducer is related only to the thickness of the wafer on which the cMUTs are engraved, and to the connections.
- the cMUTs bars have inter-element acoustic couplings that are almost non-existent.
- Fig. 17 is a representation of an example of a tissue excitation device 1700 and / or an organ of a human or animal subject embodying the invention.
- the device 1700 comprises a sound transducer 100 as represented in FIG. 1 and means 1702 for supplying the transducer 100 with a frequency excitation signal less than the central frequency of the transducer 100.
- the invention makes it possible to also to couple on the same excitation device two different and complementary functions, namely:
- a first function dedicated to the low frequency for example 1 M Hz, with a view to performing therapy
- Figure 18 is a schematic representation of a first example of a device for performing the two functions mentioned above.
- the device 1800 shown in FIG. 18, comprises supply means 1802 and a set 1804 of sound transducers.
- Each of the sound transducers 1804 comprises cMUT membranes having exactly the same topology as the other sound transducers 1804, and therefore the same central frequency, for example between 4 and 8 M Hz.
- a portion 1806 of the sound transducers 1804 is used for the generation of a low frequency acoustic beam, for example 1 M Hz, used in therapy. These transducers 1804 are therefore used in elastic mode, below their central frequency.
- the other part 1808 1804 sound transducers is used for the generation of a high frequency acoustic beam, for example 4 to 8 M Hz, used in ultrasound imaging.
- the 1808 sound transducers are therefore excited at their center frequency or around this central frequency.
- the low frequency signals make it possible to scan the entire height of the cavity to benefit from a sufficient level of ultrasonic pressure. Therefore, in the elastic regime, a bias voltage equal to the collapse voltage divided by two (Vc / 2) and a dynamic amplitude corresponding to 100% of Vc is used.
- the sound transducers 1806 are therefore used in an elastic state and are excited with a frequency excitation signal lower than their central frequency, provided by a power supply module 1810.
- the sound transducers 1808 are excited by a broadband pulse type excitation signal, centered at the central frequency of the cMUTs associated with a bias voltage corresponding to 80% Vc and supplied by a power supply module 1812. 1808. This choice favors sensitivity in reception.
- the excitation amplitudes used for the 1808 imaging transducers are lower than the amplitudes used for the 1806 therapy transducers because the 1808 transducers are used in "resonant" mode and the pressure being proportional to the square of the frequency, it is from the start higher.
- Figure 19 is a schematic representation of a second example of a device for performing the two functions mentioned above.
- the device 1900 makes it possible to perform both functions by performing a "temporal" separation of the two functions.
- the device 1900 comprises feed means 1902 and a set of identical 1904 ultrasound transducers.
- Each 1904 ultrasound transducer is used in both therapy and imaging / diagnostics and has the same central frequency.
- the power supply means 1902 comprise a first power supply module 1906 providing a low frequency signal for therapy, for example 1 MHz, and a second power supply module 1908 providing a high frequency signal for the imaging / diagnosis, for example between 4MHz and 8MHz.
- the power supply means 1902 also comprise a selection module 1910 making it possible to select the power source of the transducers 1904, manually or automatically and optionally programmable.
- the selection module 1910 selects the power supply module 1906.
- the selection module 1910 selects the power supply module 1908.
- the advantage of the device 1900 is related to the orientation of the high frequency and low frequency beams which, with the device 1900 are perfectly superimposed.
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Abstract
Description
Claims
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
FR1056040A FR2962926B1 (en) | 2010-07-23 | 2010-07-23 | ULTRASOUND GENERATING METHOD AND DEVICE USING CMUTS, AND METHOD AND SYSTEM FOR MEDICAL IMAGING. |
PCT/FR2011/051705 WO2012010786A2 (en) | 2010-07-23 | 2011-07-18 | Method and device for generating ultrasounds implementing cmuts, and method and system for medical imaging. |
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EP2595763A2 true EP2595763A2 (en) | 2013-05-29 |
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EP11754696.0A Withdrawn EP2595763A2 (en) | 2010-07-23 | 2011-07-18 | Method and device for generating ultrasounds implementing cmuts, and method and system for medical imaging. |
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US (1) | US20130116568A1 (en) |
EP (1) | EP2595763A2 (en) |
FR (1) | FR2962926B1 (en) |
WO (1) | WO2012010786A2 (en) |
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JP6057571B2 (en) * | 2012-07-06 | 2017-01-11 | キヤノン株式会社 | Capacitive transducer |
FR2997619B1 (en) | 2012-11-08 | 2015-04-10 | Light N | PROBE AND ULTRASONIC DEVICE FOR 3D IMAGING OF THE JAW |
CN103454345B (en) * | 2013-08-20 | 2016-01-13 | 西安交通大学 | Based on the marine biochemical matter monitoring sensor of CMUT and preparation thereof and measuring method |
JP6429759B2 (en) * | 2015-10-24 | 2018-11-28 | キヤノン株式会社 | Capacitance type transducer and information acquisition device including the same |
US11061000B2 (en) * | 2016-12-01 | 2021-07-13 | Koninklijke Philips N.V. | CMUT probe, system and method |
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- 2011-07-18 EP EP11754696.0A patent/EP2595763A2/en not_active Withdrawn
- 2011-07-18 US US13/811,307 patent/US20130116568A1/en not_active Abandoned
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WO2012010786A3 (en) | 2012-05-10 |
FR2962926A1 (en) | 2012-01-27 |
WO2012010786A2 (en) | 2012-01-26 |
FR2962926B1 (en) | 2015-01-02 |
US20130116568A1 (en) | 2013-05-09 |
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