Method and apparatus for producing homogenous cavitation to enhance transdermal transport

• US 6,620,123 B1
• Filed: 07/26/2001
• Issued: 09/16/2003
• Est. Priority Date: 12/17/1999
• Status: Expired due to Fees

• Current Assignee: Sontra Medical, Inc. (Echo Therapeutics Incorporated)
• Original Assignee: Sontra Medical, Inc. (Echo Therapeutics Incorporated)
• Inventors: Mitragotri, Samir S., Warner, Nicholas F., Kost, Joseph, Kellogg, Scott C.
• Primary Examiner(s): MENDEZ, MANUEL A
• Application Number:
  US09/868,443
• Time in Patent Office: 782 Days
• Field of Search: 604/22, 604/20, 604/890.1, 604/66, 604/289, 604/290, 601/2, 601/17, 607/154
• US Class Current: 604/22
• CPC Class Codes: A61B 2017/22008 used or promoted
• CPC Class Codes: A61B 2017/22027 Features of transducers
• CPC Class Codes: A61B 2017/320073 probe
• CPC Class Codes: A61M 37/0092 using ultrasonic, sonic or infrasonic vibrations, e.g. phonophoresis

Abstract

The present invention is directed to apparatus and methods for producing homogenous cavitation. An ultrasound souce comprising an ultrasound transmitting element having an axis and a cross-section along the axis is disclosed The ultrasound transmitting element also has a first axial end and a second axial end operable to produce ultrasonic waves. The cross-section has an area having a maximum value at the first axial end and a minimum value at the second axial end. A method for producing homogenous cavitation at an area of skin comprises creating a volume of fluid having a uniformly dispersed concentration of cavitation nuclei adjacent the area of skin. Ultrasound is then applied to the volume of fluid and causes cavitation at the cavitation nuclei.

Claims

1. An ultrasound source comprising:

an ultrasound transmitting element having an axis and a first cross-section along said axis, said ultrasound transmitting element having a first axial end and a second axial end, said first axial end operable to produce ultrasonic waves; and

said first axial end comprising a matrix of ultrasound producing portions, said portions defined by a first series of parallel axial cuts and a second series of parallel axial cuts, said second series of parallel axial cuts are approximately perpendicular to said first series of parallel axial cuts and said matrix having the first cross-section;

wherein the ultrasound producing portions, which are completely bounded by said cuts, each has a substantially rectangular cross-section parallel to said first cross-section.

2. The ultrasound source of claim 1 wherein said ultrasound transmitting element comprises a cylindrical horn and said first cross-section is a circle.

3. The ultrasound source of claim 1 wherein said ultrasound transmitting element comprises a flat horn and said first cross-section is rectangular.

4. The ultrasound source of claim 3 wherein said matrix of ultrasound producing portions comprises a row of ultrasound producing portions.

5. The ultrasound source of claim 1 wherein each one of said ultrasound producing portions has a first end proximal to the ultrasound transmitting element and a second end distal to the ultrasound transmitting element.

6. The ultrasound source of claim 1 wherein the first axial end radiates ultrasound toward a skin surface and causes cavitation in a coupling medium, at the skin surface or in the skin.

7. The ultrasound source of claim 1 wherein said first end comprises an anodized coating.

8. The ultrasound source of claim 1 wherein said first end comprises carbide steel.

9. The ultrasound source of claim 8 wherein said carbide steel first end is bonded to said ultrasound transmitting element.

10. An ultrasound source comprising:

an ultrasound transmitting element having an axis and a cross-section along said axis, said ultrasound transmitting element having a first axial end and a second axial end, said second axial end operable to produce ultrasonic waves;

said cross-section having an area having a maximum value at the first axial end and a minimum value at the second axial end; and

said first axial end comprising a matrix of ultrasound producing portions, said portions defined by a first series of parallel axial cuts and a second series of parallel axial cuts, said second series of parallel axial cuts are approximately perpendicular to said first series of parallel axial cuts and said matrix having the first cross-section;

wherein the ultrasound producing portions, which are completely bounded by said cuts, each has a substantially rectangular cross-section parallel to said first cross-section.

11. The ultrasound source of claim 10 wherein said cross-section has a uniform shape.

12. The ultrasound source of claim 10 wherein said ultrasound transmitting element has a circular cross-section along said axis.

13. The ultrasound source of claim 10 wherein the ultrasound transmitting element produces an ultrasound wave pattern that produces uniformly distributed cavitation.

14. The ultrasound source of claim 10 wherein the first axial end radiates ultrasound toward a skin surface and causes uniformly distributed cavitation in a coupling medium, at the skin surface or in the skin.

15. The ultrasound source of claim 10 wherein said first end comprises an anodized coating.

16. The ultrasound source of claim 10 wherein said first end comprises carbide steel.

17. The ultrasound source of claim 16 wherein said carbide steel first end is bonded to said ultrasound transmitting element.

18. A method for producing homogenous cavitation at an area of skin comprising:

creating a volume of fluid adjacent the area of skin, said fluid having a uniformly dispersed concentration of cavitation nuclei therein; and

applying ultrasound to the volume of fluid from an ultrasound transmitting element having an axis and a cross-section along said axis, said ultrasound transmitting element having a first axial end and a second axial end, said second axial end operable to produce ultrasonic waves, said first axial end comprising a matrix of ultrasound producing portions, said portions defined by a first series of parallel axial cuts and a second series of parallel axial cuts, said second series of parallel axial cuts are approximately perpendicular to said first series of parallel axial cuts and said matrix having the first cross-section, wherein the ultrasound producing portions, which are completely bounded by said cuts, each has a substantially rectangular cross-section parallel to said first cross-section;

wherein the ultrasound causes cavitation to begin at or around the cavitation nuclei.

19. The method of claim 18 wherein the cavitation nuclei comprise appropriately sized ceramic particles.

20. The method of claim 18 wherein the cavitation nuclei comprise appropriately sized polymer particles.

21. The method of claim 18 wherein the cavitation nuclei comprise appropriately sized titanium dioxide particles.

22. The method of claim 18 wherein the cavitation nuclei comprises gas bubbles.

23. The method of claim 18 further comprising delivering a substance through the area of skin.

24. The method of claim 18 further comprising extracting analyte through the area of skin.