Comparison of different methods of fabrication of microneedle arrays

Microneedles are micron structures that provide the possibility of drug delivery, vaccination and sampling of different organs. The use of microneedles does not require special skills and training, it significantly reduces the dosage and allows the timely release of the drug. The numerous advantages of microneedles compared to other methods of drug delivery have attracted the attention of many researchers. Microneedles are made from the order of microns to millimeters using microfabrication technology using various metals, silicon and polymers. So far, various methods have been proposed for making microneedles. In this article, the conventional and widely used methods of microneedle manufacturing are presented along with their advantages and limitations in terms of the effective parameters in the selection of microneedle. Effective factors such as the type of drug, the desired mechanism for drug delivery, the dimensions and material type lead to the selection of different methods for making microneedles. Among the existing micro fabrication methods, the casting method has the ability to produce different types of microneedles, and thus has been the most popular. The casting method is simple and cheap and can be produced in high volume. Deep reactive ion etching methods make high-precision microneedles, but due to the need for advanced and expensive equipment, a skilled person, and a complex and time-consuming process, they are not capable of mass production. Meanwhile, 3D printing with fully automatic processes is a good option to choose.