To realize the full potential of MEMS devices, stiction, friction and wear in these devices must be minimized. These are key challenges to MEMS technology, limiting device realization and reliability. The proposed research develops a gas-phase lubrication process that allows the delivery of lubricant molecules to all surfaces of the MEMS device including sidewalls as well as underneath suspended parts while preventing excess delivery of lubricants that can cause destruction of the device. The gas-phase lubrication will also allow in-use lubrication of the device, i.e., the lubrication molecules can be continuously delivered to the working surface through the gas phase. The continuous supply of the lubricant to the working surface while the device is working has been the key element for the success and wide use of liquid lubricants in the modern machinery such as automobiles, ships, airplanes, etc. Virtually all moving and rubbing parts are currently lubricated with viscous liquid materials. Unfortunately, the presence of viscous liquid causes severe power dissipation problems in the MEMS device operation. This is one of the main reasons that solid-phase lubrication such as surface coatings is most widely investigated. However, any surface coatings are subject to wear, which will limit the reliability of the device. The gas-phase transport of the lubrication molecules to the working surfaces will avoid these problems associated with the liquid and solid lubricants and achieve anti-stiction, effective lubrication, and anti-wear operations of MEMS devices without interfering with the device function such as mechanical motion, optical reflection, and electrical contacts. The gas-phase lubrication can be used alone or in combination with the solid-phase lubrication.
Intellectual Merits: This research will improve fundamental understanding of thermodynamic adsorption equilibrium at the solid-gas interface as well as molecular structures in the adsorbed lubricant film. Nano-mechanical studies of adsorbed molecular films will elucidate how the films modify adhesion and friction under tribological conditions related to MEMS and other nano-device operations. Based on the fundamental understanding of film structures and properties, a very efficient gas-phase anti-stiction and lubrication process will be developed for end-fabrication release and in-use lubrication of MEMS devices.
Broader Impacts: The gas-phase lubrication process is suitable for operation over a wide temperature range and can be applied to encapsulated operation of MEMS devices as well as open-structure, ambient operation. The success of this research will stimulate more research on molecular encapsulation inside MEMS devices. This will benefit not only the development of MEMS lubrication but also other nanotechnology areas. This research will provide participating students with multidisciplinary trainings from scientific fundamentals to engineering applications. Students trained in this way are very likely to make significant contributions in advance of nanotechnology that requires multidisciplinary problem-solving skills. The graduate student of this project will be nominated for the Elmer Klaus fellowship of the Society for Tribologists and Lubrication Engineers (STLE) as well as sent to national conferences. The outreach program offering research opportunities to undergraduate students in a primarily undergraduate institution will provide valuable experience that can lead the students to higher degree education.
