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A Mems Pressure Sensor Using Electrostatic Levitation, Mohammad Mousavi, Mohammad Alzgool, Shahrzad Towfighian

Mechanical Engineering Faculty Scholarship

Applying electrostatic levitation force to the initially-closed gap-closing electrodes of our micro-electro- mechanical system (MEMS) creates multi actuation mechanisms, and opens a new world to the MEMS applications.

Electrostatic levitation allows us to measure physical quantities, such as air pressure, by exploiting pull-in instability and releasing. The beam starts from a pulled-in position by applying a voltage difference between two gap-closing electrodes. When enough voltage is applied to the side electrodes, the cantilever beam is released. At the release instant, electrostatic forces, restoring force, and surface force are applied to the cantilever. According to the experimental results of this work, …

Electrostatic Levitation: An Elegant Method To Control Mems Switching Operation, Mohammad Mousavi, Mohammad Alzgool, Shahrzad Towfighian

Mechanical Engineering Faculty Scholarship

This paper investigates the characteristics of a micro-switch that uses two side electrodes to open a normally closed switch. The side electrodes surround the xed electrode in the well-known gap-closing electrode configuration. The side electrodes can open a closed switch and be tuned to respond appropriately to outside forces. The combined electrode system dramatically improves the control of a standard gap-closing electrode configuration. In conventional switches, a DC voltage above a certain value closes the switch. To re-open the switch, the voltage difference is reduced to peel o the moving electrode. Currently the contact area is carefully designed to avoid …

Autonomous Shock Sensing Using Bi-Stable Triboelectric Generators And Mems Electrostatic Levitation Actuators, Mohammad Mousavi, Mohammad Alzgool, Shahrzad Towfighian

Mechanical Engineering Faculty Scholarship

This work presents an automatic threshold shock-sensing trigger system that consists of a bi-stable triboelectric transducer and a levitation-based electrostatic mechanism. The bi-stable mechanism is sensitive to mechanical shocks and releases impact energy when the shock is strong enough. A triboelectric generator produces voltage when it receives a mechanical shock. The voltage is proportional to the mechanical shock. When the voltage exceed a certain level, the initially pulled-in Microelectromechanical system (MEMS) switch is opened and can disconnect the current in a safety electronic system. The MEMS switch combines two mechanisms of gap-closing (parallel-plate electrodes) with electrostatic levitation (side electrodes) to …

Feasibility Study Of A Mems Threshold-Pressure Sensor Based On Parametric Resonance: Experimental And Theoretical Investigations, Mark Pallay, Meysam Daeichin, Shahrzad Towfighian

Mechanical Engineering Faculty Scholarship

A tunable threshold pressure sensor based on para- metric resonance of a microbeam subjected to electrostatic levitation is proposed. Parametric excitation can trigger a large amplitude vibration at twice the natural frequency if the mag- nitude of the driving force is large enough to overcome energy loss mechanisms in the system such as squeeze film damping. This causes a temporarily unstable response with a significant gain in oscillation amplitude over time until it is eventually capped by nonlinearities in the force or material or geometric properties. The instability divides the frequency region into two regions: distinct responses bounded by the …

Towards A High Bias Voltage Mems Filter Using Electrostatic Levitation, Mark Pallay, Ronald Miles, Shahrzad Towfighian

Mechanical Engineering Faculty Scholarship

Traditional MEMS filters use a comb drive structure that suffers from the pull- in instability, which places a significant limitation on the achievable signal-to- noise ration of the sensor. Because the output signal from a capacitive sensor

is linearly related to the applied voltage, it is desirable to use a capacitive sensor that can withstand large voltages upwards of 100V. However, the pull-in instability causes high voltages to destroy the device and a trade-off between performance and reliability must be made. Electrostatic levitation, which works by pulling electrodes apart instead of together, eliminates the pull-in instability and allows for very …

Experimental Characterization Of The Electrostatic Levitation Force In Mems Transducers, Meysam Daeichin, Ronald Miles, Shahrzad Towfighian

Mechanical Engineering Faculty Scholarship

In this study, a two-step experimental procedure is described to determine the electrostatic levitation force in MEMS transducers. In these two steps, the microstructure is excited quasi-statically and dynamically and its response is used to derive the electrostatic force. The experimental results are obtained for a 1 by 1 plate that employs 112 levitation units. The experimentally obtained force is used in a lumped parameter model to find the microstructure response when it is subjected to different dynamical loads. The natural frequency and the damping ratios in the model are identified from the experimental results. The results show this procedure …

Lateral Pull-In Instability Of Electrostatic Mems Transducers Employing Repulsive Force, Meysam Daeichin, Ronald Miles, Shahrzad Towfighian

Mechanical Engineering Faculty Scholarship

We report on the lateral pull-in in capacitive MEMS transducers that employ a repulsive electrostatic force. The moving element in this system undergoes motion in two dimensions. A two degree-offreedom mathematical model is developed to investigate the pull-in quantitatively. The nonlinear electrostatic force, which is a vector function of two spatial coordinates, is determined by calculating the potential energy of the system using a boundary element approach. The equilibrium points are found by numerically solving the nonlinear coupled static equations. A stability analysis reveals that depending on the values of the lateral and transverse stiness, the system undergoes dierent bifurcations …

Pairing Electrostatic Levitation With Triboelectric Transduction For High-Performance Self-Powered Mems Sensors And Actuators, Mark Pallay, Alwathiqbellah I. Ibrahim, Ronald N. Miles, Shahrzad Towfighian

Mechanical Engineering Faculty Scholarship

We demonstrate that an electrostatic levitation MEMS switch can be operated by applying mechanical pres- sure to a triboelectric generator. The toggling mechanism of the switch draws no current but requires a high actuating voltage, while the generator can supply a high voltage but only produces microwatts of power. The synergistic combination results in an entirely self-powered sensor and switch; the normally-closed MEMS switch can be toggled open by applying a threshold force to the generator without the need for any outside power or supplementary circuitry. A model of the MEMS switch and electrostatic force is validated with experimental data. …

A Tunable Electrostatic Mems Pressure Switch, Mark Pallay, Ronald N. Miles, Shahrzad Towfighian

Mechanical Engineering Faculty Scholarship

We demonstrate a tunable air pressure switch. The switch detects when the ambient pressure drops below a threshold value and automatically triggers without the need for any computational overhead to read the pressure or trigger the switch. The switch exploits the significant fluid interaction of a MEMS beam undergoing a large oscillation from electrostatic levitation to detect changes in ambient pressure. If the oscillation amplitude near the resonant frequency is above a threshold level, dynamic pullin is triggered and the switch is closed. The pressure at which the switch closes can be tuned by adjusting the voltage applied to the …

A Parametric Electrostatic Resonator Using Repulsive Force, Mark Pallay, Shahrzad Towfighian

Mechanical Engineering Faculty Scholarship

In this paper, parametric excitation of a repulsive force electrostatic resonator is studied. A theoretical model is developed and validated by experimental data. A correspondence of the model to Mathieu's Equation is made to prove the existence and location of parametric resonance. The repulsive force creates a combined response that shows parametric and subharmonic resonance when driven at twice its natural frequency. The resonator can achieve large amplitudes of almost 24 μm and can remain dynamically stable while tapping on the electrode. Because the pull-in instability is eliminated, the beam bounces off after impact instead of sticking to the electrode. …