A Review on Solid Microneedles for Biomedical Applications

Microelectromechanical system (MEMS)-based microneedles are an innovative way of drug delivery that increases the permeability of the skin. It generates microscopic pores inside the skin that leads to the passive diffusion of drugs for dermal microcirculation to take place. This phenomenon helps toward efficient drug penetration. MEMS microneedles are small-sized needles usually in the micron to millimeter range, normally having a length to width of about 150–550 µm and 50–300 µm. respectively. Their tip diameter varies from 1 to 80 µm that can pierce through the epidermis layer directly to dermal tissues devoid of any pain. In this paper, a broad overview of solid microneedles for biomedical applications has been presented. The objective of this review is to collect the state of art main features related to solid microneedles. Particularly, the challenges related to solid microneedles, such as materials and methods used in the fabrication of microneedles, design and their performance, testing, safety concerns, commercialization issues, and applications, have been discussed. Microneedles can be characterized conferring to their fabrication procedure, structure, materials, general shape and size, the shape of the tip, microneedle array thickness, and applications. This comprehensive review on solid microneedles may provide significant useful information for scientists or researchers working on the design and development of solid microneedles for biomedical applications.