TABLE OF CONTENTS This chapter focuses on the latest versions of actuation mechanisms capable of providing higher actuating forces to provide displacements in rectangular dimensions. Performance capabilities of the unique actuation mechanisms described in this chapter are not readily available from the actuating mechanisms discussed in Chapter 2. Electrostatic (ES) rotary microactuator, bent-beam electrothermal (BBET) microactuator, vertical comb array microactuator (VCAM), and electrochemical actuator are described with major emphasis on unique performance capabilities, design configurations, operational benefits, design simplicity, fabrication aspects, and reliability. Optimum design configurations of electrodes capable of providing uniform and reliable actuation force for the actuators are identified with particular emphasis on improved force-generating capability and higher tracking accuracy over wide bandwidths.
Potential actuator configurations capable of generating higher actuation forces are discussed. Preliminary studies performed by the author on various actuators indicate that the widely used parallel-plate (PP) configuration may generate an actuation force by an order of magnitude greater than that of the interdigitated configuration, in addition to minimum cost and complexity. This leads to a conclusion that a PP actuator configuration is best suited for applications demanding a large output force over small displacements as in the case of hard-disk drives (HDDs).
It is important to distinguish between certain terms used in the design and fabrication of actuators. For example, the most common term clearance is used to denote the separation or physical distance between two facing electrodes, whereas the term capacitance gap size refers to a normal between two facing electrodes. Attempts will be...
