ABSTRACT
This chapter provides the context of light-driven micromachines by exploring more traditional approaches to creating mechanical machines and integrated systems for the world of the very small. It also provides a brief glimpse at micro-electromechanical systems (MEMS) and the role of the microscale sensors and actuators that enable these very small machines to interact with outside world. The most common type of microsensor that has been embedded in micromachines is a strain gauge where the mechanical strain of the structural machine component is related to the change in resistance of the gauge sensor. MEMS-based micromachines and microsystems can be simple or complex and consist of one or more microsensors, electronic microcircuits to determine an action based on the sensor input(s), and microactuators to effect a change on either the mechanical structure or environment. Piezoelectric materials can also be used to generate relatively large forces over small displacement distances and, therefore, can be used to construct multi-layered microactuators.
