Nanotribology and nanomechanics of MEMS/NEMS and BioMEMS/BioNEMS materials and devices

Abstract

A number of micro/nanoelectromechanical systems (MEMS/NEMS) and BioMEMS/BioNEMS are used in commercial applications and/or are under development. Surface area to volume ratio in MEMS/NEMS is large, and surface forces such as adhesion, friction, and meniscus and viscous forces become very large compared to inertial and electromagnetic forces. Some devices are designed to execute expected functions with short durations, typically in the millisecond to picosecond range. The expected life of the devices for high speed contacts can vary from a few hundred thousand to many billions of cycles, e.g., over a hundred billion cycles for digital micromirror devices (DMDs). This puts serious requirements on materials in systems involving relative motion. Thus, there is a need for a fundamental understanding of adhesion, friction/stiction, wear, lubrication, and the role of surface contamination and environment, all on the nanoscale. Most mechanical properties are known to be scale dependent. Therefore, the properties of nanoscale structures need to be measured. For BioMEMS/BioNEMS, adhesion between biological molecular layers and the substrate, and friction and wear of biological layers can be important. Component-level studies are required to provide a better understanding of the tribological phenomena occurring in MEMS/NEMS. This chapter presents an overview of nanoscale adhesion, friction, and wear studies of materials and lubrication for MEMS/NEMS and BioMEMS/BioNEMS, and component-level studies of stiction phenomena in MEMS/NEMS devices.