Silicon microneedles for transdermal applications by electrochemical micromachining technology

We report a novel, versatile, and low-cost approach for fabrication of out-of-plane silicon microneedles for transdermal applications. Unlike state-of-the-art microneedles reported so far, the microneedles of this work feature a built-in reservoir in each single needle-core to be used in future applications for drug storing and delivery after insertion in the skin. The microneedles, with size up to ten times thinner than a human hair, height of about 100 μm, and density of 10000 needles/cm² (spatial period 100 μm) are effectively fabricated by silicon electrochemical micromachining (ECM) technology. Invitro insertion tests, which are carried out on synthetic skins made out of alginate hydrogels with different concentrations, clearly demonstrate penetration reliability of such tiny needles.