Finite element analysis of hollow out-of-plane HfO2 microneedles for transdermal drug delivery applications
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Transdermal drug delivery (TDD) based on microneedles is an excellent approach due to its advantages of both traditional transdermal patch and hypodermic syringes. In this paper, the fabrication method of hollow out-of-layer hafnium oxide (HfO2) microneedles mainly based on deep reactive ion etching of silicon and atomic layer deposition of HfO2 is described, and the finite element analysis of the microneedles based on ANSYS software is also presented. The fabrication process is simplified by using a single 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 well explains the “bed of nail” effect, 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 used for TDD applications.
KeywordsTransdermal drug delivery Microneedle HfO2 Atomic layer deposition Finite element analysis Bed of nail effect Flexible electronics Micro-electro-mechanical systems
The authors would like to thank Yiping Zhu for helpful discussions, and Tony Whipple, Mark Fisher, Paul Kimani and other members of the Minnesota Nano Center at the University of Minnesota for their advice and help.
This work was supported by the State Scholarship Fund of China (Grant No.201306145016), and theopen research fund of Shanghai Key Laboratory of Multidimensional Information Processing, East ChinaNormal University (Grant No.40500-542500-15202/007/002).
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