Densely arrayed microneedles having flow channel fabricated by mechanical dicing and anisotropic wet etching of silicon

We previously proposed a novel process combining mechanical dicing and anisotropic wet etching for fabricating arrayed MEMS structures, and used it to make solid-type microneedle structures in drug delivery systems (Shikida et al., 2004). For this report, we further developed the fabrication process for embedding two types of flow channels in our microneedle structures. One type has a channel with an opening at the base of each needle, and the other type has a cored channel in the needle. The height and pitch of the needles were 120-550 μm and 230-370 μm, respectively. The new process does not include the expensive deep RIE process, and is applicable to disposable injection and extraction needles used in bio-medical applications.