The physical world is not still but is rather very dynamic and full of motion. If sensors extend our faculties of sight, hearing, smell, and touch, then actuators must be the extension to our hands and fingers. They give us the agility and dexterity to manipulate physical parameters well beyond our reach. It is not surprising that the promise to control at a miniature scale is fascinating. Wouldn't the surgeon dream of electronically controlled precision surgical tools? And what to do when our sensors tell us of a need to locally act and control on a microscopic scale? It is actuation that affords us the ability to apply this type of feedback.

In this section, we address the use of micromachined actuators primarily in industrial and automotive applications though it is well understood that with minor modifications, these actuators can be applied to other markets. Inkjet heads and microvalves are perhaps the most notable examples to discuss. Micromachined pumps are also emerging as new products of the future. The complexity of actuated microsystems continues to increase as the technology matures, accompanied with a rapidly rising level of integration. For instance, novel microfluidic systems now integrate valves and pumps, as well as various types of sensors and interconnecting channels, and they have become a separate field of study and development [35].