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.

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

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

MEMS switches have a wide range of potential applications in radio frequency and microwave systems due to promising characteristics. However, these devices are still not widespread because of reliability issues. The weak point of the resistive MEMS switch is the contact area that degrades during operation. This paper presents a single-pole double-throw switch having an extended lifecycle due to multiple contact points. The device is based on an aluminum beam suspended on torsion springs. It contains four beams connected to each other and actuated by a common driving electrode. Each beam provides the contact of a platinum bump with a signal electrode at the same contact force. Testing of the four-beam switch and the basic single-beam device is performed in the cold switching conditions. Contact resistance and lifecycle of both devices are analyzed and compared. Degradation of the contact bumps of the four-beam switch and the main failure mechanisms are discussed.

Contact resistance and lifecycle of a single- and multiple-contact MEMS switch

The electrostatically actuated MEMS switch with resistive contact is presented. The movable electrode is a beam suspended on its torsion hinges. The contact material is platinum. The switch has an active breaking mechanism making it possible to protect it against stiction and provide a low actuation voltage. The measuring technique for the operating characteristic in the “hot” mode under a low direct current is described. The pull-in voltage and the breaking voltage, the switching time, and the dependence of the contact resistance on the number of actuation cycles are measured. The wear of contact surfaces is investigated. The operation of the switch in a bistable mode is demonstrated, in which the closed condition is maintained without applying the actuation voltage and the state transition occurs due to the active contact breaking mechanism.

Investigation of Characteristics of Electrostatically Actuated MEMS Switch with an Active Contact Breaking Mechanism

Migration of adhesive material in electrostatically actuated MEMS switch

Electrostatically actuated MEMS switch with the resistive contact is presented. Design of the switch includes the active contact breaking mechanism, which allows to detach the beam from the signal electrode in case of sticking. The mechanism is realized by the presence of two driving electrodes under the beam. The switch is fabricated by the surface micromachining. Finite element simulation and experimental investigation of the switch in a cold regime are performed.

Olga M. Koroleva

Papers

A low actuation voltage bistable MEMS switch: design, fabrication and preliminary testing