Ion Beam and Plasma Technology for Improved Biocompatible Surfaces

Abstract

Medical implant devices are being increasingly used to replace or stimulate damaged or diseased body parts. Because the body rejects any foreign matter, these components should appear, to the body, to be of natural or nonforeign material. An obvious approach is to construct prosthetics or other implant devices of “natural” material, such as bone mineral. While this can be done, in practice it is not feasible for large components since bone mineral does not possess sufficient structural or mechanical strength. Furthermore, items such as pacemakers or electrodes cannot be fabricated from bone mineral.Since it is the surface of the medical implant that is in direct contact with the body, one solution in designing the device is to choose the bulk material for mechanical strength or other properties and to hide the surface of the device with a coating of biocompatible material. Since bone mineral is one of the most biocompatible materials known, much effort has been devoted to developing surface treatment processes to deposit this material on prosthetics and other implants.The material bones and teeth are composed of is quite complex. Tooth enamel, itself a coating, is very durable and primarily composed of a hydrated form of calcium phosphate called hydroxylapatite (Ca10(PO4)A(OH)2), or HA. Bones are approximately 60–70% HA. However, it is not sufficient to simply produce a coating with the same chemical constitutents as HA.