Composite Passive Materials For Ultrasound Transducers

• US 20090156939A1
• Filed: 12/18/2007
• Published: 06/18/2009
• Est. Priority Date: 12/18/2007
• Status: Active Grant

• Current Assignee: Boston Scientific Scimed (Boston Scientific Corporation)
• Original Assignee: Boston Scientific Scimed (Boston Scientific Corporation)
• Inventors: Yuan, Jian R., Sadaka, Alain
• Granted Patent: US 7,804,228 B2
• Time in Patent Office: Days
• US Class Current: 600/459
• CPC Class Codes: G10K 11/004 Mounting transducers, e.g. provided with mechanical moving or orienting device mountings specially adapted to a particular sound-producing device, see the preceding groups G10K1/00 - G10K9/00, e.g. G10K1/26, G10K1/28, G10K9/22; arrangements of sonic watch equipment on submarines B63G8/39; buoys B63B22/00
• CPC Class Codes: G10K 11/02 Mechanical acoustic impedances; Impedance matching, e.g. by horns; Acoustic resonators
• CPC Class Codes: Y10T 29/42 Piezoelectric device making

Abstract

Provided herein are composite passive layers for ultrasound transducers having acoustic properties that can be easily tailored to the needs of the transducer application using current microfabrication techniques. In an embodiment, a passive layer comprises metal posts embedded in a polymer matrix or other material. The acoustic properties of the passive layer depend on the metal/polymer volume fraction of the passive layer, which can be easily controlled using current microfabrication techniques, e.g., integrated circuit (IC) fabrication techniques. Further, the embedded metal posts provide electrical conduction through the passive layer allowing electrical connections to be made to an active element, e.g., piezoelectric element, of the transducer through the passive layer. Because the embedded metal posts conduct along one line of direction, they can be used to provide separate electrical connections to different active elements in a transducer array through the passive layer.

Claims

1. An ultrasound transducer comprising:

an active acoustic element; and

a passive layer attached to the active acoustic element, the passive layer comprising;

a layer of material; and

a plurality of conductors embedded in the layer of material.

2. The transducer of claim 1, wherein the active acoustic element comprises a piezoelectric element.

3. The transducer of claim 1, wherein the material comprises a polymer.

4. The transducer of claim 1, wherein the conductors comprise conductive posts.

5. The transducer of claim 4, wherein the plurality of conductive posts are orientated substantially perpendicular to an acoustic emitting face of the active acoustic element.

6. The transducer of claim 4, wherein the conductive posts comprise metal posts.

7. The transducer of claim 4, wherein at least one of the conductive posts extends across a thickness of the passive layer.

8. The transducer of claim 1, wherein the passive layer forms a matching layer that acoustically couples ultrasound energy from the active acoustic element or forms a backing layer that attenuates ultrasound energy propagation below the active acoustic element.

9. The transducer of claim 1, wherein at least one of the conductors extends across a thickness of the passive layer.

10. The transducer of claim 1, further comprising an electrode deposited on a surface of the passive layer, wherein the electrode is electrically coupled to the active acoustic element by at least one of the conductors.

11. An ultrasound transducer array comprising:

a plurality of active acoustic elements; and

a passive layer attached to the plurality of active acoustic elements, the passive layer comprising;

a layer of material; and

a plurality of conductors embedded in the layer of material.

12. The transducer array of claim 11, wherein the active acoustic element comprises a piezoelectric element.

13. The transducer array of claim 11, wherein the material comprises a polymer.

14. The transducer array of claim 11, wherein the conductors comprise conductive posts.

15. The transducer array of claim 14, wherein the plurality of conductive posts are orientated substantially perpendicular to an acoustic emitting face of the active acoustic element.

16. The transducer array of claim 14, wherein the conductive posts comprise metal posts.

17. The transducer array of claim 14, wherein at least one of the conductive posts extends across a thickness of the passive layer.

18. The transducer array of claim 11, wherein the passive layer forms a backing layer that attenuates ultrasound energy propagation below the active acoustic elements or forms a matching layer that acoustically couples ultrasound energy from the active acoustic elements.

19. The transducer array of claim 11, further comprising a plurality of electrodes deposited on a surface of the passive layer, wherein each of the electrodes is electrically coupled to one of the active acoustic elements by at least one of the conductors.

20. The transducer array of claim 19, wherein each of the electrodes is electrically coupled to a different one of the active acoustic elements.

21. The transducer array of claim 11, further comprising an integrated circuit (IC) chip electrically coupled to at least one of the active acoustic elements by at least one of the conductors.

22. The transducer array of claim 21, wherein the IC chip is bonded to the passive layer.

23. The transducer array of claim 21, wherein the IC chip comprises a plurality of electrical contacts, and each one of the electrical contacts is electrical coupled to a different one of the active acoustic elements in the transducer array by at least one of the conductors.

25. The method of claim 23, further comprising curing the photoresist layer after the conductive posts are formed.

24. A method of fabricating a transducer, comprising:

coating a photoresist layer on an active acoustic element;

exposing the photoresist layer to light through a mask to transfer a pattern from the mask to the photoresist layer;

removing portions of the photoresist layer based on the transferred pattern to create a plurality of voids in the photoresist layer; and

depositing conductive material in the voids to form conductive posts embedded in the photoresist layer.