Finite element analysis of hollow HfO2 microneedles for transdermal drug delivery

Microneedles are an important tool for promoting transdermal drug delivery, especially for macromolecular drugs. In this paper, the fabrication method of hollow hafnium oxide (HfO₂) microneedles mainly based on deep reactive ion etching of silicon and atomic layer deposition of HfO₂, and the finite element analysis of the microneedles based on ANSYS software are presented. The fabrication process is simplified by using only one mask. The finite element analysis of a single microneedle shows that the flexibility of the microneedles can be easily adjusted for various applications. The finite element analysis of a 3×3 HfO₂ microneedle array applied on the skin explains the “bed of nail” effect nicely, i.e., the skin is not liable to be pierced when the density of microneedles in array increases. The presented research work here provides useful information for design optimization of HfO₂ microneedles.