Micropositioning

Abstract

Micropositioning is required in many industrial segments as well as in everyday life. It is often utilized, without being recognized, in applications such as cars, cameras, or even when looking at internet pictures from space taken by telescopes. In such applications, small but accurate movements can significantly improve the performance and usability of the device. For scientific and engineering purposes micropositioning is widely used in research and production facilities such as AFM (atomic force microscope), SEM (scanning electron microscope), FIB (focused ion beam), micromanipulators (e.g., cell manipulators), active vibration dampers, and assembling and production devices, for example, in electronics and semiconductor manufacturing (Hubbard et al. 2006). Demand for wider and more efficient utilization of micropositioning is growing due to trends toward miniaturization in electronics as well as its wider exploitation in application fields. There are several different materials and actuation schemes upon which micropositioning systems can be based. If especially small size, low forces, and high frequency are required for the system, electrostatic actuators are a good option. However, they are able to produce only a limited range of displacement with high voltage unless a comb structure instead of the basic capacitor plate configuration is employed. For low-voltage applications, thermal as well as magnetic actuators are widely used. Thermal actuators are usually comparable in size to electrostatic actuators but suffer also from a limited range of motion that usually has to be amplified mechanically. In contrast, magnetic and magnetostrictive actuators provide relatively large displacement but require the use of coils to generate the magnetic field and therefore can be bulky and expensive. Additionally, these approaches rely on actuation by current and therefore consume power while holding a static position. In this chapter, the general properties and requirements of piezoelectric micropositioners, their control and sensor techniques, and some commercial applications are discussed. © 2008 Springer-Verlag US.