Analysis of Ferroelectric Negative Capacitance-Hybrid MEMS Actuator Using Energy-Displacement Landscape

TL;DR

This paper introduces an energy-based analytical framework for ferroelectric negative capacitance hybrid MEMS actuators, enabling better understanding of their static and dynamic behaviors, including effects of adhesion, for low-voltage operation.

Contribution

It presents a novel energy-displacement analysis method for hybrid MEMS actuators incorporating ferroelectric negative capacitance, including adhesion effects, which was not previously available.

Findings

Hybrid MEMS actuators operate at lower voltages compared to standalone devices.

Pull-in voltage remains unaffected by adhesion, while pull-out voltage decreases.

The framework aligns well with analytical and numerical predictions.

Abstract

We propose an energy-based framework to analyze the statics and dynamics of a ferroelectric negative capacitance-hybrid Microelectromechanical System (MEMS) actuator. A mapping function that relates the charge on the ferroelectric to displacement of the movable electrode, is used to obtain the Hamiltonian of the hybrid actuator in terms of displacement. We then use graphical energy-displacement and phase portrait plots to analyze static pull-in, dynamic pull-in and pull-out phenomena of the hybrid actuator. Using these, we illustrate the low-voltage operation of the hybrid actuator to static and step inputs, as compared to the standalone MEMS actuator. The results obtained are in agreement with the analytical predictions and numerical simulations. The proposed framework enables straightforward inclusion of adhesion between the contacting surfaces, modeled using van der Waals force. We show that the pull-in voltage is not affected, while the pull-out voltage is reduced due to adhesion. The proposed framework provides a physics-based tool to design and analyze negative capacitance based low-voltage MEMS actuators.