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Post-Touchdown Dynamics of an Electrostatically Actuated MEMS Device

oliver oreilly's picture

Dear Colleague

Our (open access) paper on the post-touchdown dynamics of an electrostatically actuated MEMS device has just appeared in IJSS:

Nate N. Goldberg and Oliver M. O'Reilly, Electrostatically actuated MEMS in the post-touchdown regime: The thin-dielectric limit and a novel reduced-order model for release dynamics"

Graphical Abstract can be found here

Microelectromechanical systems (MEMS) often make use of a type of plate-based electrostatic actuator that can, under certain conditions, come into contact with a dielectric-coated electrode. After this “touchdown,” the presence of a free boundary between the contacting and non-contacting regions of the plate induces strong nonlinearities in the system, significantly affecting its dynamics. We construct and analyze the mechanics of an idealized actuator after touchdown, focusing especially on the case where the dielectric is very thin and neglecting as many sources of nonlinearity as feasible in order to isolate the effect of contact.

After characterizing the static equilibria, we construct a reduced-order dynamic model and investigate its application to the problem of vibration-assisted stiction repair, in which structural vibrations are employed to release the actuator from the touchdown configuration. This model has several features that are interesting in their own right, including a saddle–node bifurcation and finite-time blow-up.

The approach used in the paper synthesizes concepts from configurational mechanics, fracture mechanics, and nonlinear dynamics, and serves as a blueprint for constructing more sophisticated models of touchdown dynamics that incorporate important practical effects. We are guided in our approach by our earlier works [1,2] on the dynamics of contacting rods. 


[1] Nate N. Goldberg and Oliver M. O’Reilly On contact point motion in the vibration analysis of elastic rodsJournal of Sound and Vibration 487, 115579 (2020).

[2] Nate N. Goldberg and Oliver M. O'Reilly Pervasive nonlinear vibrations due to rod-obstacle contactNonlinear Dynamics, 2021 


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