Method of making radio-opaque tipped, sleeved guidewire and product

A method of making a radio-opaque tipped, sleeved guidewire, which comprises:

• (a) providing a bendable solid core piece of a predetermined length, having a control end and a distal end and having a predetermined core diameter, and providing a shrinkable polymeric sleeve formed of a first polymer composition said first polymer composition being a polyacrylonitrile-containing composition and having a first diameter at least as large as said core diameter and capable of having a second, smaller diameter from shrinkage of said sleeve, wherein said second diameter is less than said core diameter;
• (b) placing said polymeric sleeve over said core piece while said polymeric sleeve has its first diameter, and placing it so as to leave one end of said polymeric sleeve covering at least a portion of the distal end of said core piece and so as to leave a portion of said polymeric sleeve overhanging said distal end of said core piece;
• (c) providing a mixture of a radio-opaque metal powder and a second polymer composition, said second polymer composition being capable of forming a physical bond with said first polymeric composition of said polymeric sleeve;
• (d) inserting said mixture into the overhanging polymeric sleeve at the distal end of said core piece to establish a separate area of said mixture of radio-opaque metal powder and said second polymer composition;
• and,
• (e) shrinking said polymeric sleeve to its second, smaller diameter and forming said physical bond between said first polymer composition and said second polymer composition while maintaining said separate area of said mixture of radio-opaque metal powder and said second polymer composition.