Surface Adhesion and Friction in Microelectromechanical Systems: Measurement and Modification Techniques

Microscopic devices that can perform sensing, actuation, and control, known as microelectromechanical systems (MEMS), are projected to lead to new technologies with profound impacts in science and engineering. However, there are several limitations that must be overcome before MEMS could be fully utilized in various applications. In particular, because of the low stiffness and large surface-to-volume ratio of MEMS, high adhesion and friction forces between proximity and contacting surfaces limit the device efficiency and often lead to premature failure. Basic study of adhesion and friction under MEMS conditions requires special microdevices fabricated by surface micromachining. The basic features of such MEMS devices are presented herein together with suitable surface modification techniques for reducing surface adhesion and friction, such as surface texturing and deposition of low surface energy solid films and self-assembled monolayers.