STEP-DOWN COAXIAL MICROWAVE ABLATION APPLICATORS AND METHODS FOR MANUFACTURING SAME

• US 20140296839A1
• Filed: 03/28/2014
• Published: 10/02/2014
• Est. Priority Date: 03/29/2013
• Status: Active Grant

• Current Assignee: Covidien LP (Medtronic Plc)
• Original Assignee: Covidien LP (Medtronic Plc)
• Inventors: Brannan, Joseph D.
• Granted Patent: US 9,987,087 B2
• Time in Patent Office: Days
• US Class Current: 606/33
• CPC Class Codes: A61B 18/1815 using microwaves
• CPC Class Codes: A61B 2017/00526 Methods of manufacturing
• CPC Class Codes: A61B 2018/00577 Ablation
• CPC Class Codes: A61B 2018/1861 with an instrument inserted into a body lumen or cavity, e.g. a catheter
• CPC Class Codes: A61B 2018/1892 Details of electrical isolations of the antenna
• CPC Class Codes: Y10T 156/10 Methods of surface bonding and/or assembly therefor

Abstract

Microwave ablation applicators and methods for manufacturing the microwave ablation applicators are disclosed. A microwave ablation applicator includes a feed-line segment, a step-down segment, and a radiator base segment. The feed-line segment includes a first inner conductor, a first dielectric disposed on the first inner conductor, and a first outer conductor disposed on the first dielectric. The step-down segment includes a second inner conductor, a second dielectric disposed on the second inner conductor, and a second outer conductor disposed on the second dielectric. The radiator base segment includes a third inner conductor disposed on the third inner conductor, a third outer conductor disposed on the proximal end of the third dielectric so as to form a feed gap at a distal end of the radiator base segment, a balun dielectric disposed on the third outer conductor, and a balun outer conductor disposed on the balun dielectric.

Claims

1. A microwave ablation applicator comprising:

a feed-line segment including a first inner conductor, a first dielectric disposed on the outer surface of the first inner conductor and having a first face in a plane perpendicular to the longitudinal axis of the first inner conductor, and a first outer conductor disposed on the outer surface of the first dielectric;

a step-down segment including a second inner conductor, a second dielectric having a diameter less than the diameter of the first dielectric and disposed on the outer surface of the second inner conductor, and a second outer conductor disposed on the outer surface of the second dielectric; and

a radiator base segment including a third inner conductor, a third dielectric having a diameter less than the diameter of the first dielectric and disposed on the outer surface of the third inner conductor, a third outer conductor disposed on the outer surface of the proximal end of the third dielectric so as to form a feed gap at a distal end of the radiator base segment, a balun dielectric disposed on the outer surface of the third outer conductor, and a balun outer conductor disposed on the outer surface of the balun dielectric, the third outer conductor having a length that is less than the length of the third dielectric so as to leave a feed gap.

2. The microwave ablation applicator according to claim 1, wherein one or more of the feed-line segment, the step-down segment, and the radiator base segment is rigid, semi-rigid, or flexible.

3. The microwave ablation applicator according to claim 1, wherein the diameter of the second and third inner conductors are equal to the diameter of the first inner conductor.

4. The microwave ablation applicator according to claim 1, wherein the second and third inner conductors are an extension of the first inner conductor.

5. The microwave ablation applicator according to claim 1, wherein the outer diameter of the balun conductor is equal to or approximately equal to the outer diameter of the first outer conductor of the feed-line segment.

6. The microwave ablation applicator according to claim 1, wherein the step-down segment tapers from a first diameter at proximal end of the step-down segment to a second smaller diameter at a distal end of the step-down segment.

7. The microwave ablation applicator according to claim 1, wherein the step-down segment includes multiple steps.

8. The microwave ablation applicator according to claim 7, wherein a ferrule is disposed at each of the steps of the step-down segment.

9. The microwave ablation applicator according to claim 1, wherein the length of the step-down segment is scaled by the dielectric constant of the second dielectric.

10. The microwave ablation applicator according to claim 1, wherein the feed-line segment, the step-down segment, and the radiator base segment are machined from a coaxial feed-line core including an inner conductor and a dielectric insulator disposed around the inner conductor.

11. The microwave ablation applicator according to claim 1, wherein at least one of the first dielectric, the second dielectric, the third dielectric, and the balun dielectric is dielectric tape.

12. The microwave ablation applicator according to claim 1, wherein the second dielectric is a foamed PTFE, low-density PTFE (LDPTFE), microporous PTFE, tape-wrapped PTFE, tape-wrapped and sintered PTFE, or PFA.

13. The microwave ablation applicator according to claim 1, wherein the second outer conductor is a silver-plated copper flat-wire braid, a solid-drawn copper tube, a conductive ink-coated PET heat shrink, a silver-coated PET heat shrink, or a silver-plated copper-clad steel braid.

14. A microwave ablation applicator comprising:

a coaxial cable including a coaxial feed-line segment, and impedance step-down segment, a radiator base segment, and a coaxial balun disposed on the radiator base segment;

a radiating section attached to a distal end of the radiator base segment; and

a dielectric buffering and cooling segment configured to receive the coaxial cable and attached radiating section.

15. The microwave ablation applicator according to claim 14, wherein one or more of the feed-line segment, the step-down segment, and the radiator base segment is rigid, semi-rigid, or flexible.

16. The microwave ablation applicator according to claim 14, wherein the outer diameter of the coaxial balun is equal to or approximately equal to the outer diameter of the coaxial feed-line segment.

17. The microwave ablation applicator according to claim 14, wherein the dielectric buffering and cooling segment includes a first tube and a second tube disposed within the first tube, the second tube defining an outflow conduit between the inner surface of the first tube and the outer surface of the second tube, and defining an inflow conduit between the inner surface of the second tube and the outer surfaces of the coaxial cable and attached radiating section.

18. The microwave ablation applicator according to claim 14, wherein the dielectric buffering and cooling segment includes a first tube defining inflow and outflow conduits for carrying cooling fluid.