Skin penetration and fracture strength testing of silicon dioxide microneedles

This research aims to validate the utility of silicon dioxide microneedles as a fluid delivery medium. Circular as well as square lumen microneedles were fabricated via MEMS processing. Successful penetration into skin was verified by measuring insertion force using a load cell and also by performing histology of the skin. Axial as well as shear fracture strength analysis of the microneedles was done to quantify usage limits. Fracture limits of circular and square shaped silicon dioxide needles show reduced strength of square needles; which is pronounced in the case of shear fracture. The average axial fracture limit of circular needles was about 3.15 gf, and was 2.08 gf for square needles. The average shear fracture limit of circular needles was 2.21 gf, and 0.65 gf for square ones.

► We study use of silicon dioxide microneedles for fluid delivery into human skin.
► Insertion force into skin was measured and skin toughness was calculated.
► Histology of skin shows successful fluid transfer to the epidermis.
► Axial and shear fracture strength of square needles is lower than circular ones.
► Lower strength of square needles is more pronounced in case of shear fracture.