Effects of stability asymmetry in parametrically actuated MEMS sensors on phase flip probability

This work investigates how stability symmetry affects the solution tendency in two common MEMS sensors operating in degenerate parametric resonance. Prior work showed that a phase-squeezing event occurring prior to bifurcation can be used as a precise tracking parameter in mass sensing applications. Here we demonstrate that stability asymmetry has no effects on the probability of solution going to either of the two nontrivial stable branches of the pitchfork bifurcation. Experiments show that whether the device has perfect symmetry or not results in 50% probability distribution to either branch of the solution. In other words, stability asymmetry has no effect on the shapes of the potential wells. This finding provides confidence in tuning of MEMS devices without losing the general response characteristics of parametric resonance. Much higher sensitivity in parametric mass sensing can be achieved by tuning the stability symmetry with almost vertical slope.