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In this study, isotropic wet etching technology has been developed to achieve the pyramidal needle structures on one side polished chemical pure titanium substrate. Different etchants, mask materials and substrate materials combinations were investigated respectively for process optimization. A steady etch rate in excess of 2µm/min has been achieved with sputtered Ni mask. For the first time, bulk titanium out-of-plane microneedle array was fabricated with excellent sharpness. By aqueous oxidation, nanostructured porous titania was generated on the surface of the microneedle, which not only enhanced the biocompatibility of titanium devices and implants but also provided an approach for drug loading. With its high fracture toughness, high strength, and excellent biocompatibility, the bulk titanium out-of-plane microneedles may play an important role in the future clinical applications.

Nanostructured titania (NST) is attracting more and more attention due to its porousness and high surface to volume ratio. A novel process to fabricate integrated NST thin film at low temperature (80-90°C) is presented. NST features were formed by oxidizing Ti films in aqueous hydrogen peroxide. The optimal conditions of aqueous oxidation are: 85°C, aqueous 10% H2O2 solution, 20 min of water bath time. Crack-free NST features of 100 ?m × 100 ?m were successfully fabricated. Two polymer masking materials, SU8 and Parylene, were proved to be compatible with this process, selective NST oxidation could be carried out at an ultra low temperature below 100°C.