Fabrication of bulk titanium out-of-plane microneedles

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 2 mum/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.