Recently it has been shown that structural vibrations are an efficient means to repair stiction failed microcantilever
beams. Experiments and analysis have identified excitation parameters (amplitude and frequency) that successfully initiated the debonding process between the microcantilever and the substrate. That analysis could not describe what happened after the debonding process was initiated. For example it could not predict if the beam would transition from a s-shaped to an arc-shaped configuration or even be repaired to a free-standing beam. The current research examines the post-initiation behavior of stiction failed microcantilever beams. A new-coupled fracture/vibration model is formulated and used to track the evolution of the repair in order to determine the extent of repair under various conditions. This model successfully explains phenomenological observations made during the experiments regarding the repair process being dependent on direction of frequency sweeps, complete and partial repair, and monitors the degree of repair no repair, partial repair or complete repair along with releases time associated with such repairs.
Recently, it has been proposed that sticking contact between micro-scale components may be relieved (i.e., the components may be unstuck) using structural vibrations. The means to excite these vibrations plays a critical role in the physical mechanism responsible for the initiation of stick-release. For example, it has been shown that mechanical actuation using, say, an instrumented nanoindentor is most effective near a resonant frequency. Aside from showing the fundamental mechanism responsible for the repair (resonance), it also provides insight for choosing optimal excitation parameters, such as excitation amplitude and frequency, for stick-release. In the present paper, periodic electrical excitation is explored as a means of inducing structural vibrations. It is shown that electrical excitation produces stick-release through a fundamentally different mechanism than its mechanical counterpart. Here, stick-release is achieved via unstable self-excited vibrations. This fact has a significant influence on the practical matter of choosing appropriate excitation parameters to produce the desired repair. Using the underlying physics, appropriate parameter combinations are mapped.
Commercial applications of micro-electromechanical systems (MEMS) continue to be plagued by reliability issues encountered during fabrication and operation. One of the most prevalent problems is the adhesion between adjacent components since adhesive forces are known to promote wear and defect-related failures. In extreme circumstances, the adhesion is large enough to prevent separation, a phenomenon commonly referred to as stiction-failure. The objective of current work is to determine analytically whether dynamic excitation may be used to repair stiction-failed cantilevers. This is accomplished by relating the structural dynamic response to the de-cohesion of stiction-failed micro-cantilever beams under various loading conditions.