Step-wise micro-fabrication techniques of microneedle arrays with applications in transdermal drug delivery – A review

Abstract

Traditional drug delivery methods like oral pills, nasal sprays, skin creams and intravenous injections have many limitations with respect to action time and patient compliance among others. Transdermal patches are also developed but they are less effective due to the low diffusion through the stratum corneum (top layer) of the skin. Hence, microneedle arrays are developed which pierce the stratum corneum without being too deep, to avoid triggering pain receptors in the dermis. Microneedles are being researched globally as a drug delivery modality for many diseases, both as medication and vaccination. Extensive research in this domain has brought about novel methods for microneedle fabrication.Fabrication process of microneedle arrays (MNA) demands manufacturing techniques which are very accurate at the micro scale with very less error margins. This paper reviews extensively used and published microfabrication techniques like laser ablation, 3D printing, micro-mechanical machining and lithography for microneedle arrays and aims to explain the fabrication process in detail. It also looks into different types of microneedles, a variety of applications and the fabrication methods employed for the same.