Adhesion of micro-cantilevers subjected to mechanical point loading: modeling and experiments

This paper presents experimental and theoretical results that characterize the adhesion of MEMS cantilevers by means of mechanical actuation. Micro-cantilever beams are loaded at various locations along the freestanding portion of the beam using a nanoindenter. Transitions between three equilibrium configurations (freestanding, arc-shaped, and s-shaped beams) and the response to cyclic loading are studied experimentally. The resulting mechanical response is used to estimate the interface adhesion energy (using theoretical models), and to quantify the energy dissipated during cyclic loading. The experiments reveal interesting behaviors related to adhesion: (i) path dependence during mechanical loading of adhered beams, (ii) history dependence of interfacial adhesion energy during repeated loading, and (iii) energy dissipation during cyclic loading, which scales roughly with estimated cyclic changes in the size of the adhered regions. The experimental results are interpreted in the context of elementary fracture-based adhesion and contact models, and briefly discussed in terms of their implications regarding the nature of adhesion and future modeling to establish adhesion mechanisms.