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1. (WO2017001636) SYSTÈME À ULTRASONS ET PROCÉDÉ DE TRANSMISSION D'IMPULSIONS ULTRASONORES
Note: Texte fondé sur des processus automatiques de reconnaissance optique de caractères. Seule la version PDF a une valeur juridique

CLAIMS:

1. An ultrasound system (1) comprising:

a probe (10) including an array (110) of CMUT (capacitive micromachined ultrasound transducer) cells (100), each cell comprising a substrate (112) carrying a first electrode (122) of an electrode arrangement, the substrate being spatially separated from a flexible membrane (114) including a second electrode (120) of said electrode arrangement by a gap (118), the flexible membrane comprising a mass element (140) in a central region (17, 17'); and

a voltage supply (45) coupled to said probe and adapted to, in a transmission mode of the ultrasound system, provide the respective electrode arrangements of at least some of the CMUT cells with a voltage including:

a bias voltage component driving the at least some of the CMUT cells into a collapsed state in which a central part of the flexible membrane contacts the substrate, said central part including the central region; and

a stimulus component having a set frequency for resonating the respective flexible membranes of the at least some of the CMUT cells in said collapsed state, wherein the mass element of each of the at least some CMUT cells forces at least the central region of the flexible membrane of said cell to remain in contact with the substrate during said resonating.

2. The ultrasound system (1) of claim 1, wherein each electrode arrangement further comprises a third electrode (124) carried by the substrate (112), wherein the third electrode (124) is located in between the first electrode (120) and the second electrode (122) and is electrically insulated from the first electrode by a dielectric layer (123), wherein the voltage supply (45) is adapted to apply the stimulus across the respective first and second electrodes and to apply the bias voltage to the respective third electrodes of the at least some CMUT cells.

3. The ultrasound system (1) of claim 1 or 2, wherein the voltage supply (45) is further adapted to provide the respective electrode arrangements of at least some of the

CMUT cells (100) with a further voltage that forces the at least some CMUT cells in the collapsed state during a reception mode of said probe (10).

4. The ultrasound system (1) of any of claims 1-3, wherein the bias voltage supply (45) comprises:

a first stage (102) adapted to generate the bias voltage component of said voltage during said transmission mode, wherein the bias voltage component is sufficient to force the at least some CMUT cells (100) in the collapsed state; and

a second stage (104) adapted to generate the stimulus component of said voltage.

5. The ultrasound system (1) of any of claims 1-4, wherein the flexible membrane (114) comprises a first material and the mass element (140) comprises a second material, the second material having a higher density than the first material.

6. The ultrasound system (1) of claim 5, wherein the second material is a metal or metal alloy, or a heavy non-metal material.

7. The ultrasound system (1) of any of claims 1-6, wherein the mass element (140) is positioned on the flexible membrane (114).

8. The ultrasound system (1) of any of claims 1-6, wherein the mass element (140) is integrated in the flexible membrane (114).

9. The ultrasound system (1) of any of claims 1-8, wherein the mass element

(140) has a cylindrical or annular shape.

10. The ultrasound system (1) of any of claims 1-9, wherein the ultrasound system is an ultrasound diagnostic imaging system or an ultrasound therapeutic system.

11. A method (200) of ultrasonic pulse transmission, comprising:

providing (201) a probe (10) including an array (110) of CMUT (capacitive micromachined ultrasound transducer) cells (100), each cell comprising a substrate (112) carrying a first electrode (122) of an electrode arrangement, the substrate being spatially separated from a flexible membrane (114) including a second electrode (120) of said electrode arrangement by a gap (118), the flexible membrane comprising a mass element (140) in a central region (17, 17'); and

providing (203) the respective electrode arrangements of at least some of the CMUT cells with a voltage including:

a bias voltage component driving the at least some of the CMUT cells into a collapsed state in which a central part of the flexible membrane contacts the substrate, said central part including the central region; and

a stimulus component having a set frequency for resonating the respective flexible membranes of the at least some CMUT cells in said collapsed state, wherein the mass element of each of at least some CMUT cells forces at least the central region of the flexible membrane of said cell to remain in contact with the substrate during said resonating.

12. The method (200) of claim 11, wherein each electrode arrangement further comprises a third electrode (124) carried by the substrate (112), wherein the third electrode

(124) is located in between the first electrode (120) and the second electrode (122) and is electrically insulated from the first electrode by a dielectric layer (123), the method further comprising applying the stimulus component across the respective first and second electrodes and applying the bias voltage component to the respective third electrodes of the at least some CMUT cells.

13. The method (200) of claim 11 or 12, further comprising periodically altering the set frequency to periodically alter a resonance frequency of the at least some CMUT cells (100).

14. The method (200) of any of claims 11-13, further comprising periodically altering the bias voltage component driving the at least some of the CMUT cells (100) into a collapsed state to alter the respective areas of the central parts (17, 17') of the at least some CMUT cells.

15. The method (200) of any of claims 11-14, further comprising providing, in a reception mode, the respective electrode arrangements (120, 122) of at least some of the CMUT cells (100) with a further voltage forcing the at least some CMUT cells in the

collapsed state.