Biocompatible surfaces and devices incorporating such surfaces
The invention is an improved biocompatible surface for a variety of medical purposes. The biocompatible surface employs a unique tight microstructure that demonstrates enhanced cellular response in the body, particularly when placed in contact with blood. As a blood contact surface, the present invention can be beneficially employed in a wide variety of implantable devices and in many other devices and equipment that come in contact with blood.
1. A blood contact surface comprising
a polytetrafluoroethylene microstructure of nodes and fibrils in both an x direction and in a substantially perpendicular y direction;
wherein the nodes and fibrils have a mean distance between adjacent nodes of 5 micron or less; and
wherein the mean width of the 32 largest nodes in a representative 10,000× SEM micrograph is less than about 1.5 micron.
2. The blood contact surface of claim 1 wherein the nodes and fibrils have a ratio of mean distances between adjacent nodes in the x and y directions of about 2:1 to 1.1.
3. The blood contact surface of claim 2 wherein the ratio of mean distances between adjacent nodes in the x and y directions is about 1:1.
4. The blood contact surface of claim 1 wherein the expanded polytetrafluoroethylene comprises a multi-axially expanded polytetrafluoroethylene.
5. The blood contact surface of claim 4 wherein the expanded polytetrafluoroethylene comprises a bi-axially expanded polytetrafluoroethylene.
6. The blood contact surface of claim 1 wherein the expanded polytetrafluoroethylene comprises fibrils extended outwardly from the nodes in substantially perpendicular directions.
7. The blood contact surface of claim 1 wherein the mean width of the nodes comprises less than about 1.25 micron.
8. The blood contact surface of claim 1 wherein the mean width of the nodes is less than about 1 micron.
9. The blood contact surface of claim 1 wherein the ratio of mean distances between adjacent nodes in the x and y directions is less than 1.5 to 1.
10. The blood contact surface of claim 1 wherein the microstructure substantially prevents cellular in-growth.
11. The blood contact surface of claim 1 wherein the blood contact surface is incorporated in an implantable medical device.
12. The blood contact surface of claim 1 wherein the blood contact surface is incorporated in a non-implantable medical device.
13. The blood contact surface of claim 1 wherein the mean distance between adjacent nodes is less than about 4 micron.
14. The blood contact surface of claim 13 wherein the mean distance between adjacent nodes is less than about 3 micron.
15. The blood contact surface of claim 11 wherein the implantable medical device includes a stent.
16. The blood contact surface of claim 1 wherein endothelial cells attach intimately to the node and fibril microstructure.