TABLE OF CONTENTS This chapter describes various actuation mechanisms, their performance capabilities, and potential applications. Various actuation mechanisms will be described with major emphasis on cantilever beam reliability, force-generating capacity, response time, design complexity, and drive voltage or input power requirements. Cantilever beam configuration and design requirements for each actuation mechanism are identified to meet specific output force level and actuation voltage requirements. A radio frequency microelectromechanical systems (RF-MEMS) switch is selected just to understand the critical roles played by various elements of the actuation mechanism deployed in the design of the switch. The microelectromechanical systems (MEMS)-based RF switch has two operating states similar to a conventional RF semiconductor switch. Switching between these two states is accomplished through the mechanical displacement of a freely movable, microstructural flexible membrane called as an armature or a single beam microactuator. One end of the beam is attached to a top electrode, while the other end to a bottom electrode as illustrated in Figure 2.1 [1]. In brief, the core of a MEMS switch is the flexible membrane with metallic contacts moving between the top and bottom electrodes as shown in Figure 2.1. The planar view of an RF-MEMS switch shows the flexible membrane, top and bottom electrodes, and input and output terminals. The mechanical displacement is provided by the microactuator using the force provided by an appropriate actuation mechanism depending on the air gap, spring constant of the beam, and driving voltage applied.
