Mechanism of the Transition From In Plane Buckling to Helical Buckling for a Stiff Nanowire on an Elastomeric Substrate

Abstract

In this work, the compressive buckling of a nanowire partially bonded to an elastomeric substrate is studied via finiteelement method (FEM) simulations and experiments. The buckling profile of the nanowire can be divided into three regimes, i.e., the inplane buckling, the disordered buckling in the outofplane direction, and the helical buckling, depending on the constraint density between the nanowire and the substrate. The selection of the buckling mode depends on the ratio d/h, where d is the distance between adjacent constraint points and h is the helical buckling spacing of a perfectly bonded nanowire. For d/h > 0.5, buckling is inplane with wavelength خ»â€‰= 2d. For 0.27 < d/h < 0.5, buckling is disordered with irregular outofplane displacement. While, for d/h < 0.27, buckling is helical and the buckling spacing gradually approaches to the theoretical value of a perfectly bonded nanowire. Generally, the inplane buckling induces smaller strain in the nanowire, but consumes the largest space. Whereas the helical mode induces moderate strain in the nanowire, but takes the smallest space. The study may shed useful insights on the design and optimization of highperformance stretchable electronics and threedimensional complex nanostructures.