Experimental and theoretical analyses of effect of ZnO nanowire growth on mechanical properties of microcantilevers for dynamic sensing applications

Abstract

In this paper, we have demonstrated a hydrothermal approach to grow ZnO nanowires (NW) on top of a microcantilever of dimension 250μm × 90μm × 0.7μm and investigated the effect of these nanowires over the mechanical properties of the microcantilever using the Laser Doppler Vibrometry (LDV) and Nanoindentation studies. Experimental results show that growth of ZnO nanowires on microcantilever increases its spring constant. Furthermore, based on the experimental results of changes in resonant frequency, we have also calculated the stress developed due to the growth of ZnO nanowires on the microcantilever considering both surface stress and geometric effect independently. We found that the stress induced due to the geometric effect was an order of magnitude higher as compared to that of the surface stress. Active mass sensing using the microcantilever/microresonator platform has been extensively reported in literature due to their high sensitivity and low detection limit. Researchers have used metal oxide (MOX) nanowires to improve the sensitivity of microcantilevers. The approach presented in this report can be used for important design considerations while fabricating sensors based on this platform.