The importance of thermoelastic damping as a fundamental dissipation mechanism for small-scale mechanical resonators is evaluated in light of recent efforts to design high-Q micrometer- and nanometer-scale electromechanical systems. The equations of linear thermoelasticity are used to give a simple derivation for thermoelastic damping of small flexural vibrations in thin beams. It is shown that Zener’s well-known approximation by a Lorentzian with a single thermal relaxation time slightly deviates from the exact expression.

Thermoelastic Damping in Micro- and Nano-Mechanical Systems.

Over the last couple of decades, the advancement in Microelectromechanical System (MEMS) devices is highly demanded for integrating the economically miniaturized sensors with fabricating technology. A sensor is a system that detects and responds to multiple physical inputs and converting them into analogue or digital forms. The sensor transforms these variations into a form which can be utilized as a marker to monitor the device variable. MEMS exhibits excellent feasibility in miniaturization sensors due to its small dimension, low power consumption, superior performance, and, batch-fabrication. This article presents the recent developments in standard actuation and sensing mechanisms that can serve MEMS-based devices, which is expected to revolutionize almost many product categories in the current era. The featured principles of actuating, sensing mechanisms and real-life applications have also been discussed. Proper understanding of the actuating and sensing mechanisms for the MEMS-based devices can play a vital role in effective selection for novel and complex application design.

/pdf/a-review-of-actuation-and-sensing-mechanisms-in-mems-based-450ftrxe90.pdf

A Review of Actuation and Sensing Mechanisms in MEMS-Based Sensor Devices

MEMS switch is a movable device manufactured by means of semiconductor technology, possessing many incomparable advantages such as a small volume, low power consumption, high integration, etc. This paper reviews recent research of MEMS switches, pointing out the important performance indexes and systematically summarizing the classification according to driving principles. Then, a comparative study of current MEMS switches stressing their strengths and drawbacks is presented, based on performance requirements such as driven voltage, power consumption, and reliability. The efforts of teams to optimize MEMS switches are introduced and the applications of switches with different driving principles are also briefly reviewed. Furthermore, the development trend of MEMS switch and the research gaps are discussed. Finally, a summary and forecast about MEMS switches is given with the aim of providing a reference for future research in this domain.

Research Status and Development Trend of MEMS Switches: A Review.

Commercial success of microelectromechanical systems (MEMS) switches is limited by several issues. A high actuation voltage requires special circuitry solutions that increase size and cost of the switch. Another problem is the lack of reliability due to the stiction phenomenon. This paper presents a single-pole double-throw MEMS switch with electrostatic actuation and resistive contact. The device is based on an aluminum beam suspended by the torsion springs over the driving and signal electrodes. The design provides the pull-in voltage as low as 4.9 V. At the same time, the switch is equipped with the mechanism that protects it from stiction. The device is able to operate in the passive and active opening regimes. Recovery of the device after stiction in the hot switching conditions is demonstrated. In the cold mode, stiction is not observed at the transmitted DC power up to 25 mW. The resonant properties and response time of the switch are investigated. The on-resistance and the lifecycle are discussed. The proposed design is characterized by the high mechanical reliability. The main reason of failure is an increase of the on-resistance because of carbon accumulation on the platinum contacts.

Stiction-protected MEMS switch with low actuation voltage

The research at hand deals with the mechanical behavior of beam-like nanostructures. Nanobeams are assembled of multiple layers of different materials and geometry giving a layered nanobeam. To properly address experimentally noticed size effects in structures of this type, an adequate nonlocal elasticity formulation must be applied. The present model relies on the stress-driven integral methodology that effectively circumvents known deficiencies of other approaches. As a main contribution, a set of differential equations and boundary conditions governing the underlaying mechanics is proposed and applied to two benchmark examples. The obtained results show the expected stiffening nonlocal behavior exhibiting most of smaller and smaller structures and modern devices.

https://www.mdpi.com/2073-8994/12/5/717/pdf

Nonlocal Mechanical Behavior of Layered Nanobeams

MEMS switch with the electrostatic actuation and the resistive contact was fabricated using surface micromachining. The movable electrode of the switch was the three-layer metallic cantilever having nanoscale thickness and high lengthto- thickness ratio. Low stiffness of the cantilever allowed to approach relatively low values of the actuation voltage. The theoretical analysis and experimental study of the switching characteristics was performed.

Electrostatically actuated MEMS switch with resistive contact

Resonant properties of the three-layer metallic cantilevers with 40-120 nm thickness were investigated. Two types of cantilevers were fabricated: Cr/Al/Cr and Ti/Al/Ti. Dependencies of the fundamental resonant frequency and Q-factor on the cantilever length, width and thickness were experimentally obtained. The experimental data analysis and the comparison with the theoretical predictions were performed. Dependence of material properties on the cantilever thickness was not observed. Energy losses in the surface layer of the cantilever were the dominant energy loss mechanism.

http://iopscience.iop.org/article/10.1088/1742-6596/541/1/012018/pdf

Resonance properties of metallic nanocantilevers

Electrostatically actuated MEMS switch with resistive contact is presented. Movable electrode of the switch is a beam suspended by torsion springs. Low stiffness of springs allows to achieve the low values of the actuation voltage. Main feature of the switch is a mechanism of the active contact breaking, allowing to solve the problem of adhesive sticking of the beam to the signal electrode. The active opening of the switch is realized by the presence of two driving electrodes. The theoretical analysis, finite element simulation and experimental investigation of the switch characteristics are performed.

http://iopscience.iop.org/article/10.1088/1742-6596/643/1/012091/pdf

Victor V. Naumov

Papers

Electrostatically actuated MEMS switch with resistive contact

Resonance properties of metallic nanocantilevers

MEMS switch with the active contact breaking mechanism