Dual frequency band ultrasound transducer arrays

• US 7,727,156 B2
• Filed: 07/26/2006
• Issued: 06/01/2010
• Est. Priority Date: 07/26/2005
• Status: Active Grant

• Current Assignee: Bjørn A. J. Angelsen, Näsholm, Peter, Rune Hansen, Svein-Erik Maasoey, Tonni F. Johansen
• Original Assignee: Bjørn A. J. Angelsen, Näsholm, Peter, Rune Hansen, Svein-Erik Maasoey, Tonni F. Johansen
• Inventors: Maasoey, Svein-Erik, Näsholm, Peter, Johansen, Tonni F., Angelsen, Bjørn A. J., Hansen, Rune
• Primary Examiner(s): Winakur; Eric F
• Assistant Examiner(s): Laryea; Lawrence N
• Application Number:
  US11/493,283
• Publication Number:
  US 20070035204A1
• Time in Patent Office: 1,406 Days
• Field of Search: 600/437, 600/446, 600/443, 600/441, 600/439, 601/2, 367/140, 310/311
• US Class Current: 600/459
• CPC Class Codes: B06B 1/064 with multiple active layers
• CPC Class Codes: G01S 15/8915 using a transducer array
• CPC Class Codes: G01S 15/8952 using discrete, multiple frequencies
• CPC Class Codes: G01S 7/52022 using a sequence of pulses, at least one pulse manipulating the transmissivity or reflexivity of the medium

Abstract

Ultrasound probes that transmits/receives ultrasound pulses with frequencies both in a low frequency (LF) and a high frequency (HF) band, where the radiation surfaces of said HF and LF bands at least have a common region. Several solutions for transmission (and reception) of LF and HF pulses through the same radiation surface are given. The arrays and elements can be of a general type, for example linear phased or switched arrays, or annular arrays or elements with division in both azimuth and elevation direction, like a 1.5D, a 1.75D and a full 2D array. The LF and HF element division and array apertures can also be different.

Claims

1. An ultrasound transducer array probe for transmission from a front of the probe of ultrasound pulses in separate low frequency (LF) and high frequency (HF) bands and reception of pulses in at least the HF band, the transducer comprising:

radiation surfaces for the LF band and the HF band, wherein at least a portion of said radiation surfaces for the LF and HF bands are common in a common radiation surface,

at least in a region of the common radiation surface, a stack of layers stacked in a thickness direction substantially normal to the common radiation surface, said stack including separate LF and HF piezoelectric layers configured for respective LF and HF electro acoustic transductions, wherein said HF piezoelectric layer is disposed closer to the common radiation surface than is said LF piezoelectric layer, and

an acoustic isolation section composed of at least two acoustic layers stacked in the thickness direction and disposed between said HF and LF piezoelectric layers.

2. An ultrasound transducer array probe according to claim 1, wherein said isolation section includes a back layer with characteristic acoustic impedance greater than 17 MRayl and at least one layer with characteristic impedance less than 5 MRayl.

3. An ultrasound transducer array probe according to claim 2, wherein said back layer is made of one of the materials Cu, Ag, Au, Pd, Pt, W, or alloys of these materials, or powders of the one of the materials Cu, Ag, Au, Pd, Pt, W, or alloys of these materials, the powders being sintered or glued together.

4. An ultrasound transducer array probe according to claim 1, wherein a back layer of said isolation section comprises a ceramic layer.

5. An ultrasound transducer array probe according to claim 4, wherein said LF piezoelectric layer is made from a material comprising a ceramic/polymer composite wherein the ceramic/polymer composite is diced from the back and not fully through said LF piezoelectric layer, so that a front portion of said LF ceramic piezoelectric layer forms a laterally continuous layer that forms said back layer of said isolation section.

6. An ultrasound transducer array probe according to claim 5, wherein a 2^nd layer from the back of said isolation section is made of one of the materials Cu, Ag, Au, Pd, Pt, W, or alloys of these materials, or powders of the one of the materials Cu, Ag, Au, Pd, Pt, W, or alloys of these materials, the powders being sintered or glued together.

7. An ultrasound transducer array probe according to claim 1, wherein said stack includes a plurality of transducer elements, and said radiation surfaces include an LF transmit surface, an HF transmit surface, and at least one of an LF receive surface and an HF receive surface, wherein at least one of said radiation surfaces is made as a sparse array of said transducer elements, and where potential grating lobes of HF and LF transmit apertures of the probe do not overlap in space.

8. An ultrasound instrument utilizing an ultrasound probe according to claim 1, wherein a thickness of the stack is the same throughout the entire common radiation surface, and sizes of LF and HF transmit and receive apertures are selected electrically by the electrical connection to array elements in said stack.

9. An ultrasound instrument utilizing an ultrasound probe according to claim 8, wherein an active LF transmit aperture is selected one of

a) automatically by the instrument depending on an image range, an ultrasound imaging modality and an application, and

b) directly by the instrument operator through instrument controls.

10. An ultrasound transducer array probe according to claim 1, further comprising:

a backing material on which said stack is mounted, and

an acoustic matching section for the HF band placed in front of said HF piezoelectric layer.

11. An ultrasound transducer array probe according to claim 1, wherein each of said acoustic layers extends continuously contiguous with at least one of said LF and HF piezoelectric layers.

12. An ultrasound transducer array probe for transmission from a front of the probe of ultrasound pulses in separate low frequency (LF) and high frequency (HF) bands and reception of pulses in at least the HF band, the transducer comprising:

radiation surfaces for the LF band and the HF band, wherein at least a portion of said radiation surfaces for the LF and HF bands are common in a common radiation surface,

at least in a region of the common radiation surface, a stack of layers stacked in a thickness direction substantially normal to the common radiation surface portion, wherein said stack includes a piezoelectric layer configured for one of LF and HF electro acoustic transduction, and a substrate layer with cmut/pmut based transduction membranes on a front face configured for the other of LF and HF electro acoustic transduction, wherein

the stack of layers includes an HF array with at least one HF array element and an LF array with at least one LF array element respectively in the region of the radiation surfaces for the LF band and HF band, each element of the at least one LF array element within the common radiation surface having a larger radiation surface than does each element of the at least one HF array element within the common radiation surface, and wherein

said substrate layer based on cmut/pmut transduction membranes is placed to the front of said piezoelectric layer.

13. An ultrasound transducer array probe according to claim 12, wherein said LF electro acoustic transduction is obtained by said piezoelectric layer.

14. An ultrasound transducer array probe according to claim 12, wherein said HF electro acoustic transduction is obtained by said piezoelectric layer.

15. An ultrasound transducer array probe according to claim 12, wherein said stack includes a plurality of transducer elements, and said radiation surfaces include an LF transmit surface, an HF transmit surface, and at least one of an LF receive surface and an HF receive surface, wherein at least one of said radiation surfaces is made as a sparse array of said transducer elements, and wherein potential grating lobes of HF and LF transmit apertures of the probe do not overlap in space.

16. An ultrasound instrument utilizing an ultrasound probe according to claim 12, wherein a thickness of the stack is the same throughout the entire common radiation surface, and sizes of LF and HF transmit and receive apertures are selected electrically by the electrical connection to array elements in said stack.

17. An ultrasound instrument utilizing an ultrasound probe according to claim 16, wherein an active LF transmit aperture is selected one of

a) automatically by the instrument depending on an image range, an ultrasound imaging modality and an application, and

b) directly by the instrument operator through instrument controls.

18. An ultrasound transducer array probe for transmission from a front of the probe of ultrasound pulses in separate low frequency (LF) and high frequency (HF) bands and reception of pulses in at least the HF band, the transducer comprising:

radiation surfaces for the LF band and the HF band, wherein at least a portion of said radiation surfaces for the LF and HF bands are common in a common radiation surface,

a substrate, wherein at least in a region of the common radiation surface, separate cmut/pmut based LF and HF transduction membranes comprising at least one LF transduction membrane and at least one HF transduction membrane are arranged on said substrate and configured for respective LF and HF electro acoustic transductions, and wherein

said LF and HF transduction membranes form an HF array having at least one HF array element and an LF array having at least one LF element within the common radiation surface, each element of the at least one LF array element within the common radiation surface having a larger radiation surface than does each element the at least one HF array element within the common radiation surface.

19. An ultrasound transducer array probe according to claim 18, wherein within said common radiation surface the at least one HF transduction membrane is placed in front of the at least one LF transduction membrane.

20. An ultrasound transducer array probe according to claim 18, wherein within said common radiation surface the at least one HF transduction membrane is placed side by side of the at least one LF transduction membrane, at a distance from each other such that LF and HF beams appear to originate from overlapping elements.

21. An ultrasound transducer array probe according to claim 18, wherein said radiation surfaces include an LF transmit surface, an HF transmit surface, and at least one of an LF receive surface and an HF receive surface, wherein at least one of said radiation surfaces is made as a sparse array of the LF array elements or the HF array elements, and wherein potential grating lobes of HF and LF transmit apertures of the probe do not overlap in space.

22. An ultrasound instrument utilizing an ultrasound probe according to claim 18, wherein a thickness of the substrate is the same throughout the entire common radiation surface, and sizes of LF and HF transmit and receive apertures are selected electrically by the electrical connection to array elements in said substrate.

23. An ultrasound instrument utilizing an ultrasound probe according to claim 22, wherein an active LF transmit aperture is selected one of

a) automatically by the instrument depending on an image range, an ultrasound imaging modality and an application, and

b) directly by the instrument operator through instrument controls.

24. An ultrasound transducer array probe for transmission from a front of said probe of ultrasound pulses in separate low frequency (LF) and high frequency (HF) bands and reception of pulses at least in the HF band, the transducer comprising:

different arrays of transducer elements configured for respective LF and HF electro-acoustic transduction, the array for the LF electro-acoustic transduction having at least one LF array element and the array for the HF electro-acoustic transduction having at least one HF array element, and

radiation surfaces for the LF band and the HF band, wherein at least a portion of said radiation surfaces for the LF and HF bands are common in a common radiation surface,

wherein each element of the at least one LF array element within the common radiation surface has a larger radiation surface than does each element of the at least one HF array element within the common radiation surface, and

wherein the radiation surfaces include at least an LF transmit surface for LF band transmission and an HF transmit surface for HF band transmission, the outer boundaries of said LF transmit surface being at least in a region outside the outer boundaries of said HF transmit surface.

25. An ultrasound transducer array probe according to claim 24, wherein said array for the LF electro-acoustic transduction and said array for the HF electro-acoustic transduction are each arranged as one of

a single element array,

an annular array of transducer elements,

a linear array of transducer elements, and

a two dimensional array of transducer elements.

26. An ultrasound instrument utilizing an ultrasound probe according to claim 24, wherein

a thickness of the structure of the different arrays is the same throughout the entire common radiation surface, and sizes of LF and HF transmit and receive apertures are selected electrically by the electrical connection to the transducer elements, and wherein

active LF and HF transmit apertures are selected one of

a) automatically by the instrument depending on an image range, an ultrasound imaging modality and an application, and

b) directly by the instrument operator through instrument controls.

27. An ultrasound transducer array probe according to claim 24, wherein the radiation surfaces also include an HF receive surface for HF band reception, and the transducer elements are selectively activatable so that the HF receive surface is larger than the LF transmit surface.

28. An ultrasound transducer array probe for transmission from a front of said probe of ultrasound pulses in separate low frequency (LF) and high frequency (HF) bands and reception of pulses in at least the HF band, the transducer comprising:

different arrays of transducer elements configured for respective LF and HF electro-acoustic transduction, the array for the LF electro-acoustic transduction having at least one LF array element and the array for the HF electro-acoustic transduction having at least one HF array element, and

radiation surfaces for the LF band and the HF band, wherein at least a portion of said radiation surfaces for the LF and HF bands are common in a common radiation surface,

wherein each element of the at least one the LF array element within the common radiation surface has a larger radiation surface than does each element of the at least one HF array element within the common radiation surface, and

wherein the radiation surfaces include at least an LF transmit surface for LF band transmission and an HF transmit surface for HF band transmission, said LF transmit surface being not common with the HF transmit surface in a region around the center of said HF transmit surface.

29. An ultrasound transducer array probe according to claim 28, wherein said array for the LF electro-acoustic transduction and said array for the HF electro-acoustic transduction are each arranged as one of

a single element array,

an annular array of transducer elements,

a linear array of transducer elements, and

a two dimensional array of transducer elements.

30. An ultrasound instrument utilizing an ultrasound probe according to claim 28, wherein

a thickness of the structure of the different arrays is the same throughout the entire common radiation surface, and sizes of LF and HF transmit and receive apertures are selected electrically by the electrical connection to the transducer elements, and wherein

active LF and HF transmit apertures are selected one of

a) automatically by the instrument depending on an image range, an ultrasound imaging modality and an application, and

b) directly by the instrument operator through instrument controls.

31. An ultrasound transducer array probe according to claim 28, wherein the radiation surfaces also include an HF receive surface for HF band reception, and the transducer elements are selectively activatable so that the HF receive surface is larger than the LF transmit surface.

32. An ultrasound transducer array probe for transmission from a front of said probe of ultrasound pulses in separate low frequency (LF) and high frequency (HF) band and reception of pulses in at least the HF band, the transducer comprising:

radiation surfaces for the LF band and the HF band including at least an LF transmit surface for LF band transmission and an HF transmit surface for HF band transmission, wherein at least a portion of said radiation surfaces for the LF and HF bands are common in a common radiation surface,

LF array elements and HF array elements, at least said LF array elements being selectively activatable so that the size of the LF transmit surface can be selectively varied to be one of

a) equal to the HF transmit surface,

b) at least in a region outside the HF transmit surface,

c) in a central region of said HF transmit surface at which there is no active LF transmit surface, and

d) a combination of b) and c), and wherein

the LF array elements within the common radiation surface have larger radiation surfaces with a larger distance between neighboring element centers, than do the HF array elements within the common radiation surface.

33. An ultrasound instrument utilizing an ultrasound probe according to claim 32, wherein an active LF transmit aperture is selected one of

a) automatically by the instrument depending on an image range, an ultrasound imaging modality and an application, and

b) directly by the instrument operator through instrument controls.