Design and development of a biocompatible painless microneedle by the ion sputtering deposition method

The purpose of this study is to design, generate, and characterize a titanium alloy microneedle, which can be used in Bio-MEMS such as a Health Monitoring System (HMS) for blood sugar level. One of the most important requirements for Bio-MEMS is a microneedle with an inner diameter of 100 μm and an outer diameter of 200 μm, which mimics the female mosquito's painless blood extraction mechanism. In this study, a microneedle was produced and evaluated taking into account: (1) selection of a biocompatible material from titanium alloys by the cytotoxic assay; (2) the effect of changing of inner diameter of the microneedle on the time taken to extract a volume of blood through the microneedle (the contribution rate for the inner diameter of a microneedle was 49% when volume flow rate was defined as an evaluation value); (3) RF magnetron sputter deposition methods for generating microtubes 4 mm long with an inner diameter of 100 μm and outer diameter of 200 μm; and (4) evaluation of blood extraction speeds. A flow rate 7.3 μl/s was obtained for pure titanium and titanium alloy (Ti–15Mo–5Zr–3Al) microneedles.