Mosaic arrays using micromachined ultrasound transducers

• US 20040174773A1
• Filed: 03/06/2003
• Published: 09/09/2004
• Est. Priority Date: 03/06/2003
• Status: Active Grant

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Thomenius, Kai, Smith, Lowell Scott, Mills, David M., Hazard, Christopher Robert, Wodnicki, Robert G., Fisher, Rayette A.
• Granted Patent: US 6,865,140 B2
• Time in Patent Office: Days
• US Class Current: 367/174
• CPC Class Codes: B06B 1/0292 Electrostatic transducers, e.g. electret-type

Abstract

An ultrasound transducer array includes a multiplicity of subelements interconnected by a multiplicity of microelectronic switches, each subelement comprising a respective multiplicity of micromachined ultrasound transducer (MUT) cells. The MUT cells within a particular subelement are hard-wired together. The switches are used to configure the subelements to form multiple concentric annular elements. This design dramatically reduces complexity while enabling focusing in the elevation direction during ultrasonic image data acquisition.

Claims

1. A mosaic array comprising a multiplicity of subelements, each of said subelements comprising a respective multiplicity of micromachined ultrasound transducer (MUT) cells, and each MUT cell comprising a top electrode and a bottom electrode, wherein the top electrodes of the MUT cells making up any particular subelement are hard-wired together, and the bottom electrodes of those same MUT cells are hard-wired together.

2. The mosaic array as recited in claim 1, wherein each subelement comprises a respective group of seven MUT cells arranged in a daisy configuration.

3. The mosaic array as recited in claim 1, wherein each subelement comprises a respective group of 19 MUT cells arranged in a hexagonal configuration.

4. The mosaic array as recited in claim 1, wherein each subelement comprises a respective group of N MUT cells arranged in a predetermined pattern, wherein N is an integer greater than unity.

5. The mosaic array as recited in claim 1, wherein adjacent subelements are separated by gaps sufficient to reduce cross talk.

6. The mosaic array as recited in claim 1, further comprising a multiplicity of switches, each of said multiplicity of switches being connected to a respective one of said subelements.

7. The mosaic array as recited in claim 6, further comprising a semiconductor substrate, said switches being fabricated within said semiconductor substrate and said cMUT cells being fabricated on said semiconductor substrate.

8. The mosaic array as recited in claim 6, further comprising a programming circuit that controls said multiplicity of switches.

9. The mosaic array as recited in claim 8, wherein said programming circuit controls said switches so that the aperture on transmit is different than the aperture on receive.

10. The mosaic array as recited in claim 8, wherein said programming circuit controls said switches so that switched-on subelements form a generally annular ring.

11. The mosaic array as recited in claim 8, wherein said programming circuit controls said switches so that switched-on subelements form a non-annular ring.

12. The mosaic array as recited in claim 8, wherein said programming circuit controls said switches so that switched-on subelements are circumferentially distributed along a circle at equal angular intervals.

13. The mosaic array as recited in claim 8, wherein said programming circuit controls said switches so that switched-on subelements form first and second elements, said first element comprising a first set of said subelements and said second element comprising a second set of said subelements, said first element being surrounded by said second element.

14. The mosaic array as recited in claim 13, wherein said programming circuit controls said switches so that switched-on subelements form a third element comprising a third set of said subelements, said second element being surrounded by said third element.

15. The mosaic array as recited in claim 8, wherein said programming circuit controls said switches so that switched-on subelements having similar delay values produce a steered beam.

16. The mosaic array as recited in claim 8, wherein said programming circuit modifies the bias voltage across the active aperture to generate a shaped modulation across said MUT cells.

17. The mosaic array as recited in claim 8, wherein said programming circuit independently adjusts the bias voltage for each subelement to compensate for sensitivity variation.

32. The mosaic array as recited in claim 1, wherein transduction from electrical to acoustic and vice versa is accomplished via use of piezo-electric materials.

18. An ultrasound transducer array comprising a multiplicity of subelements interconnected by a multiplicity of microelectronic switches, each subelement comprising a respective multiplicity of MUT cells, and each MUT cell within a particular subelement being hard-wired together.

19. The array as recited in claim 18, further comprising programming means for interconnecting selected subelements to form respective elements.

20. The array as recited in claim 19, wherein said respective elements form multiple concentric annuli of an electronically formed annular array.

21. The array as recited in claim 20, wherein said electronically formed annular array is moved, under electronic control, across said transducer array.

22. The array as recited in claim 19, wherein the borders of said annuli are changed electronically in response to the temporal relationship between the echoes received by said subelements and the total beamsum signal of an electronically formed annular array.

23. The array as recited in claim 19, wherein said subelements are interconnected in a first configuration during transmit and a second configuration during receive, said first and second configurations being different.

24. The array as recited in claim 18, wherein each subelement comprises a respective group of seven MUT cells arranged in a daisy configuration.

25. The array as recited in claim 18, wherein each subelement comprises a respective group of 19 MUT cells arranged in a hexagonal configuration.

26. The array as recited in claim 18, wherein each subelement comprises a respective group of N MUT cells arranged in a predetermined pattern, wherein N is an integer greater than unity.

27. The array as recited in claim 18, wherein adjacent subelements are separated by gaps sufficient to reduce cross talk.

28. A method of making an ultrasound transducer, comprising the following steps:

fabricating a substrate having a multiplicity of microelectronic switches therein; and

micromachining a multiplicity of MUT cells on said substrate, said MUT cells being interconnected in clusters, each cluster of interconnected MUT cells being connected to a respective one of said microelectronic switches.

29. An ultrasound transducer comprising:

a multiplicity of MUT cells, each MUT cell comprising a respective top electrode and a respective bottom electrode, wherein the top electrodes of said MUT cells are hard-wired together and the bottom electrodes of said MUT cells are hard-wired together;

a microelectronic switch having an output terminal connected to said interconnected top electrodes or to said interconnected bottom electrodes; and

a driver circuit having an output terminal connected to an input terminal of said microelectronic switch for driving said multiplicity of MUT cells to generate ultrasound waves when said microelectronic switch is turned on.

30. The transducer as recited in claim 29, wherein said multiplicity consists of seven MUT cells arranged in a daisy configuration.

31. The transducer as recited in claim 29, wherein said multiplicity consists of 19 MUT cells arranged in a hexagonal configuration.