Fabrication of Hollow-type Silicon Microneedle Array Using Microfabrication Technology

Hollow-type microneedle array can be used for painless, continuous and stable drug delivery through a human skin. The needles must be sharp and have sufficient length in order to penetrate the epidermis. An array of hollow-type silicon microneedles was fabricated by using deep reactive ion etching and HNA wet etching with two oxide masks. Isotropic etching was used to create tapered tips of the needles, and anisotropic etching of Bosch process was used to make the extended length and holes of microneedles. The microneedles were formed by three steps of isotropic, anisotropic, and isotropic etching in order. The holes were made by one anisotropic etching step. The fabricated microneedles have 170 μm width, 40 μm hole diameter and 230 μm length.