Method and apparatus for direct laser cutting of metal stents

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.

1 - 19 . (canceled)  
   
   
       20 . A method of manufacturing a stent, comprising: 
 providing a length of thin wall tubing having and outer surface and an inner surface;    focusing a laser beam on said outer surface while rotationally and axially shifting said tubing to cut a pattern therein defining a stent;    preventing any portion of said laser beam that passes through said cut pattern from impinging on said inner surface of said tubing.    
   
   
       21 . The method of  claim 20 , wherein preventing any portion of said laser beam that passes through said cut pattern from impinging on said inner surface is achieved by positioning a mandrel within said thin wall tubing.  
   
   
       22 . The method of  claim 21 , wherein said mandrel is free to roll within said thin wall tubing while said thin wall tubing is being rotationally shifted.  
   
   
       23 . The method of  claim 20 , wherein preventing any portion of said laser beam that passes through said cut pattern from impinging on said inner surface is achieved by positioning a hollow tube within said thin wall tubing.  
   
   
       24 . The method of  claim 23 , wherein said tube has an opening formed therein for admitting said laser beam.  
   
   
       25 . The method of  claim 24 , further comprising cooling said thin wall tubing by forcing a jet of gas outwardly through said opening in said tube.  
   
   
       26 . The method of  claim 25 , wherein said gas is reactive.  
   
   
       27 . The method of  claim 26 , wherein said gas comprises oxygen.  
   
   
       28 . The method of  claim 26 , wherein said gas comprises compressed air.  
   
   
       29 . The method of  claim 25 , wherein said gas is inert.  
   
   
       30 . The method of  claim 29 , wherein said gas is selected from the group consisting of argon, helium and nitrogen.  
   
   
       31 . The method of  claim 29 , further comprising removing a tail of molten material formed by said jet of gas exiting said thin wall tubing.  
   
   
       32 . The method of  claim 31 , wherein said tail of molten material is chemically removed.  
   
   
       33 . The method of  claim 31 , wherein said tail of molten material is mechanically removed.  
   
   
       34 . A method of manufacturing a stent, comprising: 
 providing a length of thin wall tubing having and outer surface and an inner surface;    focusing a laser beam on said outer surface while rotationally and axially shifting said tubing to cut a pattern therein defining a stent;    preventing any slag generated by said laser cutting said pattern from impinging on said inner surface of said tubing.    
   
   
       35 . The method of  claim 34 , wherein preventing any slag generated by said laser cutting said pattern from impinging on said inner surface is achieved by positioning a hollow tube within said thin wall tubing.  
   
   
       36 . The method of  claim 35 , wherein said tube has an opening formed therein for admitting said laser beam.  
   
   
       37 . The method of  claim 36 , further comprising flowing a gas through said tube.  
   
   
       38 . The method of  claim 37 , wherein said gas flow is achieved by negative pressure.  
   
   
       39 . The method of  claim 37 , wherein said gas flow is achieved by positive pressure.