Fabrication of bio-inspired composite coatings for titanium implants using the micro-dispensing technique

Abstract

Bio-inspired composite coating, which resembles the unique nano-structured composite bone tissue, is greatly needed in biomedical implant applications. The target of this coating is to create a continuous transition from tissue to implant surface, and modulate the biological response between the implant and host tissue. Our study on this bio-inspired composite coating is to fabricate organic---inorganic composite coatings (OICCs) and functionally graded coatings (FGCs). In this paper, a few commonly used coating methods have been evaluated on their capabilities on OICCs and FGCs fabrication. Compared with other available methods, the drop-on-demand (DoD) micro-dispensing technique enables us not only to flexibly fabricate multi-material coating at micron scale, but also to reliably construct multi-layer structures with varied material property distribution within a layer and/or among layers. This DoD micro-dispensing technique has been characterized based on three type of biomaterials (hydroxyapatite, titanium oxide and collagen) and dispensing parameters. The micro-fabrication process has been further investigated with regards to its capabilities on OICCs and FGCs. The fabricated samples on titanium substrate are characterized in terms of material distribution, adhesion, layer thickness and uniformity. The results show that the DoD micro-dispensing technique is capable to fabricate OICC and FGC samples in a single process. A comprehensive study on fabrication process and biological test will be conducted in the next stage.