Review of Patents for Microneedle Application Devices Allowing Fluid Injections Through the Skin

Microneedles have been developed in the past few years as a new means of transdermal drug delivery. They indeed present many advantages compared to injections using hypodermic needles (reduced risk of contamination and epidermic reactions), but mostly bring comfort and compliance to patients. Microneedles may be plain, opening pathways for medications to dissolve into the skin, or hollow, allowing fluid to actually enter the dermis or the hypodermis. This review focuses on the latter type of microneedles and two issues with their application: first, ensuring correct insertion into the skin (controlled and repeatable insertion depth, mainly); and second, ensuring correct fluid delivery to the dermis (controlled infusion rate). This paper thus focuses on recently published patents for hollow microneedle applicators-i.e., microneedles applicators that allow fluid delivery to the skin. Descriptions are given of several of the most relevant patents concerning this. The benefits and drawbacks of the different solutions are also described.