Design,simulation,and testing of a tunable MEMS multi-threshold inertial switch

This paper presents a tunable multi-threshold micro-electromechanical inertial switch with adjustable threshold capability.The demonstrated device combines the advantages of accelerometers in providing quantitative acceleration measurements and g-threshold switches in saving power when in the inactive state upon experiencing acceleration below the thresholds.The designed proof-of-concept device with two thresholds consists of a cantilever microbeam and two stationary electrodes placed at different positions in the sensing direction.The adjustable threshold capability and the effect of the shock duration on the threshold acceleration are analytically investigated using a nonlinear beam model.Results are shown for the relationships among the applied bias voltage,the duration of shock impact,and the tunable threshold.The fabricated prototypes are tested using a shock-table system.The analytical results agree with the experimental results.The designed device concept is very promising for the classification of the shock and impact loads in transportation and healthcare applications.

Multifrequency excitation of a clamped–clamped microbeam:Analytical and experimental investigation

Using partial electrodes and a multifrequency electrical source,we present a large-bandwidth,large-amplitude clamped–clamped microbeam resonator excited near the higher order modes of vibration.We analytically and experimentally investigate the nonlinear dynamics of the microbeam under a two-source harmonic excitation.The first-frequency source is swept around the first three modes of vibration,whereas the second source frequency remains fixed.New additive and subtractive resonances are demonstrated.We illustrated that by properly tuning the frequency and amplitude of the excitation force,the frequency bandwidth of the resonator is controlled.The microbeam is fabricated using polyimide as a structural layer coated with nickel from the top and chromium and gold layers from the bottom.Using the Galerkin method,a reduced order model is derived to simulate the static and dynamic response of the device.A good agreement between the theoretical and experimental data are reported.