Microneedle Arrays for Transdermal Delivery of Insulin: Fabrication and Skin Insertion Studies

Microneedle arrays create microscopic channels through the stratum corneum and have been proposed as a needle-free way to give insulin. This review summarises published work on how insulin microneedles are made and how their skin insertion is tested, and it reports no new data. It covers the barrier properties of skin, metal, silicon and polymer fabrication routes, mechanical and insertion testing, drug loading and delivery in animal models, and safety. Reports show that insertion depends on needle geometry, array density and application method, and that insulin delivery in diabetic rodents is feasible. Dose accuracy, long-term skin effects and human glycaemic data are still thinly documented.