Direct nanopatterning of commercially pure titanium with ultra-nanocrystalline diamond stamps

In order to directly imprint features into a hard metal such as titanium, an imprinting stamp composed of material of greater hardness is required. Diamond is the hardest known material, so is an obvious choice for the production of direct-imprint stamps. Diamond also benefits from a low surface energy, chemical inertness, high resistance to wear and is easily cleaned of contaminants, further favouring it as a stamp material of choice. Chemical vapour deposited ultra-nanocrystalline diamond (UNCD) provides similar mechanical properties to bulk single crystal diamond and can be deposited across large surface areas. This work examines the use of UNCD as a stamp medium for the transfer of nanoscale features into commercially pure titanium (cpTi) substrates. Development of an efficient and viable method for nanopatterning large, non-planar cpTi surfaces is highly desirable to control cell adhesion on the surface of bio-implants. The fabrication of UNCD nanoimprint stamps is detailed and the ability of UNCD to imprint cpTi is illustrated. A square-ordered matrix of 200 nm diameter pillars over a quarter mm square area are shown to be imprinted with the depth quantified against load (kg). The limitations of the technology are also discussed.