Enhanced global digital image correlation for accurate measurement of microbeam bending

Microbeams are simple on-chip test structures used for thin film and MEMS materials characterization. Profilometry can be combined with Euler-Bernoulli (EB) beam theory to extract material parameters, like the E-modulus. Characterization of time-dependent microbeam bending is required, though non-trivial, as it involves long term sub-microscale measurements. Here we propose an enhanced global digital image correlation (GDIC) procedure to analyze time-dependent microbeam bending. Using GDIC we extract the full-field curvature profile from optical profilometry data of thin metal microbeam bending experiments, whilst simultaneously correcting for rigid body motion resulting from drift. This work focusses on the implementation of this GDIC procedure and evaluation of its accuracy through a numerical assessment of the proposed methodology

Mechanically probing time-dependent mechanics in metallic MEMS

The reliability of metallic micro-electromechanical systems (MEMS) depends on time-dependent deformation such as creep. To this end, a purely mechanical experimental methodology for studying the time-dependent deformation of free-standing microbeams has been developed. It is found most suitable for the investigation of creep due to the simplicity of sample handling and preparation and setup design, whilst maximizing long term stability and displacement resolution. The methodology entails the application of a constant deflection to a µm-sized free-standing aluminum cantilever beam for a prolonged period of time. After this load is removed, the deformation evolution is immediately recorded by acquiring surface height profiles through confocal optical profilometry. Image correlation and an algorithm based on elastic beam theory are applied to the full-field beam profiles to yield the tip deflection as a function of time. The methodology yields the tip deflection as function of time with ~3 nm precision

A tribological study of SU-8 micro-dot patterns printed on Si surface in a flat-on-flat reciprocating sliding test

10.1007/s11249-011-9835-1Tribology Letters442167-17