Search

We present an electric power meter that capitalizes on the interaction of electrothermal strain and mechanical vibration in a micro-electro-mechanical systems (MEMS) beam undergoing the antisymmetric mode of vibration. This is achieved by using a resonant bridge driven with an electrothermal modulation technique. The change in electrical power is monitored through the alteration in the mechanical stiffness of the structure, which is tracked electrostatically. The observed deflection profile of the beam under the influence of electrothermal effects shows that the deflection geometry due to buckling exhibits similar trends as the first symmetric vibrational mode, in contrast to the antisymmetric mode. Therefore, we compare two distinct vibrational modes, converting the compressive thermal stress generated by the input electrical power via Joule heating into a shift in the resonance frequency. By employing antisymmetric vibrational mode, the output of our device is consistently monotonic to the input electrical power, even when the microbeam is experiencing buckling deflections. In addition, the sensing operation based on antisymmetric modes yields only a 1.5% nonlinear error in the response curve, which is ten times lower than that of symmetric modes. The observed deformation shape of the resonator agrees with the results obtained from multi-physics finite simulations. Finally, this approach has the potential to be extended to other frequency-shift-based sensors, allowing for higher linearity. [ABSTRACT FROM AUTHOR]

We present a novel design of a low-power micro-electro-mechanical digital to analog converter (DAC) based on a clamped-clamped micro-beam resonator with multiple split electrodes and capacitive airgaps of various widths. The proposed n-bit DAC device operates at a single drive frequency and can access one of $2^{\mathbf {n}}$ distinct stable states based on the applied digital combination. The digital inputs (binary numbers) modulate the beam resonance frequency using the electrostatic softening effect, where the larger binary numbers result in higher beam resonance frequency. Although the tested device consumes 151 pJ per conversion step with a conversion rate of 0.64 kHz, we show that by moderate downscaling of the device dimensions, femto-joules energy consumption and MHz conversion rates are attainable. [2019-0264] [ABSTRACT FROM AUTHOR]

We present multi-function microelectromechanical systems (MEMS) logic device that can perform the fundamental logic gate AND, OR, universal logic gates NAND, NOR, and a tristate logic gate using mixed-frequency excitation. The concept is based on exciting combination resonances due to the mixing of two or more input signals. The device vibrates at two steady states: a high state when the combination resonance is activated and a low state when no resonance is activated. These vibration states are assigned to logical value 1 or 0 to realize the logic gates. Using ac signals to drive the resonator and to execute the logic inputs unifies the input and output wave forms of the logic device, thereby opening the possibility for cascading among logic devices. We found that the energy consumption per cycle of the proposed logic resonator is higher than those of existing technologies. Hence, integration of such logic devices to build complex computational system needs to take into consideration lowering the total energy consumption. [2017-0041] [ABSTRACT FROM AUTHOR]

There is an increasing interest to realize smarter sensors and actuators that can deliver a multitude of sophisticated functionalities while being compact in size and of low cost. We report here combining both sensing and actuation on the same device based on a single microstructure. Specifically, we demonstrate a smart resonant gas (mass) sensor, which in addition to being capable of quantifying the amount of absorbed gas, can be autonomously triggered as an electrical switch upon exceeding a preset threshold of absorbed gas. Toward this, an electrostatically actuated polymer microbeam is fabricated and is then functionalized with a metal-organic framework, namely, HKUST-1. The microbeam is demonstrated to absorb vapors up to a certain threshold, after which is shown to collapse through the dynamic pull-in instability. Upon pull-in, the microstructure can be made to act as an electrical switch to achieve desirable actions, such as alarming. [ABSTRACT FROM AUTHOR]

Electrostatically actuated microelectromechanical system (MEMS) devices have shown prominent potential in various applications. However, despite their low power consumption, they do require high input voltages to be actuated. This is even worse if these devices are driven around their mechanical resonant state. Assuming a double resonance excitation scheme, both electrically and mechanically, activates the system's mechanical and electrical resonances simultaneously. This double resonance activation was recently verified experimentally to alleviate the problem of high actuating voltage/displacement near the resonant state. Therefore, in this work, an analytical electro-mechanical coupled model for a double-resonance-driven microbeam, assuming a classical nonlinear beam model combined with an RLC electric circuit model is first proposed and then numerically examined. Good match among the numerical simulations and the experimental data when the electrical resonance frequency band is sufficiently high is demonstrated. The suggested model can be used to further optimize certain MEMS designs and therefore fully benefit from this double resonance activation scheme in improving MEMS sensors and actuators. • Study possibility to use double resonance (Electric and Mechanical) design. • Nonlinear coupled equations are derived and validated with experimental data. • Primary resonances were both investigated theoretically and experimentally. • The double resonance design accomplishes large voltage and amplitude gains in the system without the use of high input voltages. [ABSTRACT FROM AUTHOR]