Method for making a spiral array ultrasound transducer

• US 20050015953A1
• Filed: 07/21/2003
• Published: 01/27/2005
• Est. Priority Date: 07/21/2003
• Status: Active Grant

• Current Assignee: Biosense Webster Incorporated (Johnson & Johnson)
• Original Assignee: Biosense Webster Incorporated (Johnson & Johnson)
• Inventors: Keidar, Yaron
• Granted Patent: US 7,247,269 B2
• Time in Patent Office: Days
• US Class Current: 29/25.350
• CPC Class Codes: A61B 17/2202 the ultrasound transducer being inside patient's body at the distal end of the catheter
• CPC Class Codes: A61B 2017/22051 with an inflatable part, e.g. balloon, for positioning, blocking, or immobilisation A61B2017/22048, A61B2017/3486 take precedence
• CPC Class Codes: A61N 7/022 intracavitary
• CPC Class Codes: B06B 1/0633 Cylindrical array
• CPC Class Codes: H04R 17/00 Piezoelectric transducers; Electrostrictive transducers piezoelectric or electrostrictive elements in general H10N30/00; details of piezoelectric or electrostrictive motors, generators or positioners H10N30/00
• CPC Class Codes: H04R 31/00 Apparatus or processes specially adapted for the manufacture of transducers or diaphragms therefor manufacture of microstructural arrangements of deformable or non-deformable structures in general B81C1/00182
• CPC Class Codes: H10N 30/086 by polishing or grinding
• CPC Class Codes: Y10T 29/42 Piezoelectric device making
• CPC Class Codes: Y10T 29/49124 On flat or curved insulated base, e.g., printed circuit, etc.
• CPC Class Codes: Y10T 29/49156 with selective destruction of conductive paths

Abstract

The present invention relates to a method for making an ablation transducer having a plurality of helical elements that can be operated out of phase to orient the acoustical energy beam forward or backward in the longitudinal direction. The transducers includes a cylindrical inner electrode, a cylindrical piezoelectric material disposed over the inner electrode, and a cylindrical outer electrode disposed over the cylindrical piezoelectric material. Spiral grooves are cut through at least the outer electrode separating the transducer into a plurality of functionally discrete helical transducer segments. The helical transducer segments can be operated independent from one another. An array of intertwined helical transducers arranged linearly along a helical axis are also contemplated.

Claims

1. A method for making a piezoelectric transducer having a plurality of intertwined individual helical transducer segments from comprising:

machining a ceramic material blank into a tubular configuration to form a ceramic tube;

coating the ceramic tube with a metallic layer;

machining the metal coated ceramic tube to form an inner electrode and a plurality of helically intertwined outer electrodes, each outer electrode being associated with a functionally discrete transducer segment;

transforming the ceramic material forming the ceramic tube into a piezoelectric crystal.

2. The method of claim 1 wherein the step of machining the blank comprises core drilling and turning the blank using a CNC machine.

3. The method of claim 2 wherein the step of core drilling and turning the blank comprises utilizing a quadruple YAG laser at about 700 nanometer wavelength, hooked to a rotary mandrel CAD/CAM machine.

4. The method of claim 1 wherein the step of coating the tubular ceramic material with a metallic layer comprises plating the tubular ceramic material using a metal plating process.

5. The method of claim 1 wherein the step of coating the tubular ceramic material with a metallic layer comprises sputtering the ceramic tube with metal using a sputtering process.

6. The method of claim 1 wherein the step of machining comprises laser etching the metallic coating over the ceramic tube to form inner and outer electrodes.

7. The method of claim 1 wherein the step of machining comprises laser etching the metallic coating over the ceramic tube to form helical grooves that segment the transducer into the functionally discrete transducer segments.

8. The method of claim 1 wherein the step of transforming the ceramic material forming the ceramic tube into a piezoelectric crystal comprises shorting the transducer segments.

9. The method of claim 8 wherein the step of shorting the transducer segments comprises creating a temporary connection of comparatively low resistance between the transducer segments.

10. The method of claim 1 wherein the step of transforming the ceramic material forming the ceramic tube into a piezoelectric crystal comprises poling the ceramic tube.

11. The method of claim 10 wherein the step of poling the ceramic tube comprises:

heating the ceramic tube beyond its Kerrie point; and

apply an electric field.

12. The method of claim 1 further comprising the step of polishing the outer surface of the ceramic tube before coating the ceramic tube with a metallic layer.

13. The method of claim 12 wherein the step of polishing the outer surface of the ceramic tube comprises:

mounting the ceramic tube to a spinning mandrel;

rotating the mandrel at a high rate of speed; and

contacting the rotating ceramic tube with a fine abrasive material.

14. The method of claim 1 further comprising the step of mounting the ceramic tube to a mandrel for addition support during machining.

15. The method of claim 1 further comprising the step of applying a matching layer over the segmented transducer.

16. The method of claim 15 wherein the step of applying a matching layer comprises laminating the matching layer over the transducer.

17. The method of claim 15 wherein the step of applying a matching layer comprises coating the transducer with a polymer using a process selected from the group consisting of spray coating, dip coating, chemical vapor deposition, plasma coating, co-extrusion coating, spin coating and insert molding.

18. A method of making a piezoelectric transducer, having a plurality of intertwined helical transducer segments, from a PZT ceramic tube comprising:

coating the inside and outside of the ceramic tube with a metallic layer to form an inner electrode and an outer electrode; and

etching at least the outer electrode to form a plurality of intertwined helical transducer segments.

19. A method of making an ultrasound transducer with a helical phased array comprising:

providing a cylindrical piezoelectric transducer having a piezoelectric material disposed between a cylindrical inner electrode and a cylindrical outer electrode;

machining grooves through at least the outer electrode to segment the transducer into a plurality of functionally discrete intertwined helical transducer segments.