Buckling Analysis of Hollow Microneedle in Transdermal Drug Delivery

In biomedical field, the microneedles have gained popularity in the transdermal drug delivery applications. A hollow out-of-plane microneedle with bevel shaped tip, made up of silicon material is considered in this paper. The safe insertion of such microneedles into the soft tissue without breakage plays a vital role in the design of microneedles. The primary mode of failure often found in microneedles is buckling. When the microneedle is applied with an insertion force (F) larger than the critical buckling load (P_cr), it may suffer from buckling. In this paper, the buckling analysis of silicon microneedle is performed using Finite Element Analysis. The equilibrium equation of Love’s (1944) thin rod theory is used to study the buckling effect of microneedle. A non-linear Eigen value buckling analysis of the hollow microneedle is performed. The fundamental mode 1 and the critical mode 813 are discussed. The deflection, stresses and reaction force are analysed for both the modes. The critical buckling load (P_cr) is determined to be 0.39 N and if the microneedle is applied with insertion force within this value of critical buckling load, it avoids buckling. Therefore, this critical buckling load is taken as a conservative result for designing the microneedle.