Analytical and Numerical Approaches for Optimization Design of MEMS Based SU-8 Microneedles

Abstract

This paper addresses the optimization design of the MEMS based SU-8 microneedles for blood extraction by studying the effects of axial and transverse force on SU-8 microneedles during skin insertion in both analytical and numerical points of view. The critical buckling load and maximum bending force that the needle can withstand are 4.486N and 0.123N for 1200μm length (300μm x 300μm) needle, respectively. As the results of numerical simulation, the maximum stress 1.0719MPa, which occurs at the tip, is smaller than 34MPa of yield strength of SU-8. The bending test is also proved by applying the force of 0.1N on the tip of needle, resulting 33.8MPa of maximum stress which is comparable to 34MPa of yield strength of SU-8. Based on these results, the numerical simulation also proves that the needle with our design is strong enough for inserting into human skin. © Springer-Verlag Berlin Heidelberg 2014.