Finite Element Analysis of the Critical Buckling Load in Hollow Microneedles With Lateral Support

Abstract Hollow microneedles provide minimum invasion to the skin and painless drug and vaccine delivery. However, there is a risk of fracture due to insufficient mechanical strength. The strength of microneedles might be increased by mimicking the bite of a mosquito. A mosquito has a proboscis that consists of a long needle (fascicle) surrounded by a protective sheath (labium). This sheath (labium) folds back as the fascicle pierces the skin, which provides lateral support to the fascicle. The lateral support increases the force that can be applied at the tip of the needle without buckling. In this study, the effect of lateral support on the buckling strength of a hollow microneedle made of chitin is analyzed numerically by using ABAQUS Finite Element Analysis software. The needle is modeled as a slender rod subjected to non-conservative (Beck) and conservative Euler loads simultaneously at the end. For a prescribed Beck load, the critical Euler load for buckling is obtained for various lateral elastic foundation stiffnesses. It is shown that the results of this computational study agree well with the analytical solution found in the literature. In addition, a three-dimensional finite element model is considered to study the effect of the needle tip geometry on the buckling and bending behavior of the needle.