Theoretical analysis and simulation of SU-8 microneedles for effective skin penetration and drug delivery

During the last two decades, there has been an upsurge in exploring the materials and fabrication techniques for microneedles, which promise almost painless penetration in skin. In such a scenario, it is extremely important to understand the mechanics governing the microneedles' penetration into skin alongwith a sound understanding of the flow mechanics governing the microdimensional channels of needles. This work tries to address these aspects with SU-8 as a material of choice. The calculated insertion force of 0.02N per needle is lesser than the maximum compressive, bending, and buckling forces which are 0.4N, 0.09N and 0.038N respectively for cylindrical microneedle. However, simulation results show that slanted microneedle tip may undergo bending during insertion. The theoretical calculations supported with the simulation results substantiate that SU-8 is a good structural material for microneedle fabrication.