Method and apparatus for direct laser cutting of metal stents

• US 20020193866A1
• Filed: 04/05/2002
• Published: 12/19/2002
• Est. Priority Date: 11/28/1994
• Status: Abandoned Application

• Current Assignee: Richard J. Saunders
• Original Assignee: Richard J. Saunders
• Inventors: Saunders, Richard J.
• Application Number:
  US10/117,484
• Publication Number:
  US 20020193866A1
• Time in Patent Office: Days
• US Class Current: 623/1.15
• CPC Class Codes: A61F 2/91 made from perforated sheet material or tubes, e.g. perforated by laser cuts or etched holes
• CPC Class Codes: A61F 2/915 with bands having a meander structure, adjacent bands being connected to each other
• CPC Class Codes: A61F 2002/91508 the meander having a difference in amplitude along the band
• CPC Class Codes: A61F 2002/91533 characterised by the phase between adjacent bands
• CPC Class Codes: A61F 2230/0013 Horseshoe-shaped, e.g. crescent-shaped, C-shaped, U-shaped
• CPC Class Codes: B23K 2103/05 Stainless steel
• CPC Class Codes: B23K 2103/50 Inorganic material, e.g. metals, not provided for in B23K2103/02 – B23K2103/26
• CPC Class Codes: B23K 26/073 Shaping the laser spot
• CPC Class Codes: B23K 26/0823 Devices involving rotation of the workpiece
• CPC Class Codes: B23K 26/142 for the removal of by-products
• CPC Class Codes: B23K 26/1435 involving specially adapted flow control means
• CPC Class Codes: B23K 26/1436 for pressure control
• CPC Class Codes: B23K 26/1438 for directional control
• CPC Class Codes: B23K 26/1462 Nozzles; Features related to nozzles
• CPC Class Codes: B23K 26/1476 Features inside the nozzle for feeding the fluid stream through the nozzle
• CPC Class Codes: B23K 26/18 using absorbing layers on the workpiece, e.g. for marking or protecting purposes
• CPC Class Codes: B23K 26/40 taking account of the properties of the material involved
• CPC Class Codes: G05B 19/182 characterised by the machine tool function, e.g. thread cutting, cam making, tool direction control G05B19/21 - G05B19/40 take precedence
• CPC Class Codes: G05B 2219/45041 Laser cutting
• CPC Class Codes: G05B 2219/45171 Surgery drill
• CPC Class Codes: Y10T 29/49995 : Shaping one-piece blank by removing material
• CPC Class Codes: Y10T 29/49996 : Successive distinct removal operations

Abstract

An improved expandable stent for implantation in a body lumen, such as an artery, and an improved method for making it from a single length of tubing. The stent consists of a plurality of radially expandable cut cylindrical elements generally aligned on a common axis and interconnected by one or more interconnective elements, the elements having a rectangular cross-section from cut-to-cut. The individual radially expandable cylindrical elements are disposed in an undulating pattern. The stent is manufactured by direct laser cutting from a single metal tube using a finely focused laser beam passing through a coaxial gas jet structure to impinge on the working surface of the tube as the linear and rotary velocity of the tube is precisely controlled.

Claims

1. A longitudinal flexible stent for implanting in a body lumen, comprising:

a plurality of cut cylindrical elements which are independently expandable in the radial direction and which are interconnected so as to be generally aligned on a common longitudinal axis, each cylindrical element having a rectangular cross-section from one cut edge to another; and

a plurality of connecting elements for interconnecting said cut cylindrical elements, said connecting elements configured to interconnect said cylindrical elements that are adjacent to each other.

2. The stent of claim 1, wherein said plurality of cut cylindrical elements include a plurality of peaks and valleys having a serpentine pattern.

3. The stent of claim 2, wherein said plurality of peaks and valleys include a plurality of U-shaped members, a plurality of Y-shaped members, and a plurality of W-shaped members, some of said U-shaped, Y-shaped, and W-shaped members being interconnected.

4. The stent of claim 1, wherein at least some of said plurality of cut cylindrical elements tip radially outwardly to form outwardly projecting edges upon radial expansion of said stent.

5. The stent of claim 1, wherein said cut cylindrical elements are capable of retaining their expanded condition upon the expansion thereof.

6. The stent of claim 1, wherein said stent is formed of stainless steel.

7. The stent of claim 1, wherein said stent is formed from a single piece of tubing.

19. A method as set forth in either of claim 1 or 18, and further including the step of electro-polishing said stent after it is formed.

8. A method of making an expandable metal stent, comprising the steps of:

supporting a metal tube for controlled linear and rotary motion;

impinging a finely focused laser beam upon the working surface of said metal tube; and

providing a protective mandrel within said tube to protect the tube wall opposite the tube wall being cut from being ablated by said laser beam,

whereby a precise pattern is cut into said tube to form said stent.

9. A method as set forth in claim 8, wherein said metal tube is stainless steel.

10. A method as set forth in claim 8, wherein said protective mandrel is stainless steel.

11. A method as set forth in claim 8, wherein said laser beam is circularly polarized.

12. A method as set forth in claim 11, wherein said circular polarization is accomplished by a quarter wave plate.

13. A method as set forth in claim 8, wherein said laser beam is spatially filtered.

14. A method as set forth in claim 8, wherein the size of the focused laser beam spot and depth of field is controlled by selecting beam diameter.

15. A method as set forth in claim 8, wherein the size of the focused laser beam spot and depth of field is controlled by selecting focal length of the beam focusing lens.

16. A method as set forth in claim 8, wherein said laser beam passes through a coaxial gas jet adjacent said tube.

17. A method as set forth in claim 16 wherein the gas is oxygen.

18. A method as set forth in claim 8 and further including the steps of:

ultrasonically cleaning said stent after it is formed.