Direct microneedle array fabrication off a photomask to deliver collagen through skin

To fabricate microneedle arrays directly off a photomask using a simple photolithographical approach and evaluate their potential for delivering collagen.

A simple photolithographical approach was developed by using photomask consisting of embedded micro-lenses that govern microneedle geometry in a mould free process. Microneedle length was controlled by use of simple glass scaffolds as well as addition of backing layer. The fabricated arrays were tested for their mechanical properties by using a force gauge as well as insertion into human skin with trypan blue staining. Microneedle arrays were then evaluated for the delivery of fluorescent collagen, which was evaluated using a confocal laser scanning microscope.

Microneedles with sharp tips ranging between 41.5 ± 8.4 μm and 71.6 ± 13.7 μm as well as of two different lengths of 1336 ± 193 μm and 957 ± 171 μm were fabricated by using the photomasks. The microneedles were robust and resisted fracture forces up to 25 N. They were also shown to penetrate cadaver human skin samples with ease; especially microneedle arrays with shorter length of 957 μm penetrated up to 72% of needles. The needles were shown to enhance permeation of collagen through cadaver rat skin, as compared to passive diffusion of collagen.

A simple and mould free approach of fabricating polymeric microneedle array is proposed. The fabricated microneedle arrays enhance collagen permeation through skin.