Microneedle Arrays for Drug Delivery and Diagnostics: Toward an Optimized Design, Reliable Insertion, and Penetration

In the past two decades, microneedles have been extensively studied for transdermal delivery of drug or vaccines and for bio-fluid extraction. Microneedle-based devices consist of micron-size needles that are arranged on a small patch. Despite ongoing advances in microneedle technology, one of the major problems associated with transdermal delivery or sampling is that many of the microneedle patches are not able to fully penetrate the skin surface and reach the epidermis layer of skin. In this regard, for an optimal and effective penetration-painless and safe-it is crucial to consider complex skin mechanics and how it impacts microneedle design and insertion practice. Various types of skin modelling and insertion simulations are considered, followed by discussion of ways of improving microneedle robustness, reduction of insertion force, and enhancement of penetration efficiency.