In-situ Vapor-Phase Lubrication of MEMS

• Published in: Tribology letters 2008, Vol.29 (1), p.67-74
• Main Authors: Asay, David B., Dugger, Michael T., Kim, Seong H.
• Format: Article
• Language: English
• Subjects: Actuators; Alcohol; Chemistry and Materials Science; Corrosion and Coatings; Electric contacts; Friction; Lubricating properties; Lubrication; Materials Science; Microelectromechanical systems; Nanotechnology; Original Paper; Physical Chemistry; Saturation; Silicon; Static friction; Surfaces and Interfaces; Theoretical and Applied Mechanics; Thin Films; Tribology; Vapor phase lubrication; Vapor pressure
• ISSN: 1023-8883; 1573-2711
• DOI: 10.1007/s11249-007-9283-0

In-situ vapor-phase lubrication of sidewall MicroElectroMechanical System (MEMS) devices is investigated with 1-pentanol vapor. The 1-pentanol vapor successfully maintains lubricating properties between silicon contacts of MEMS devices. This is attributed to the ability of alcohol to adsorb on the silicon surface and sustain a lubricating layer, which prevents wear of the MEMS surfaces and minimizes friction. In the presence of these vapors, MEMS devices with sliding contacts operated without failure for up to a factor of 1.7 × 10 4 longer than in dry N 2 gas alone, representing a dramatic improvement in operating life. Adhesion and friction were also investigated as a function of alcohol vapor pressure. The adhesive force between microfabricated MEMS sidewall surfaces increases from ∼30 to ∼60 nN as the alcohol vapor pressure is increased from 0 to 20% of saturation, and then only slightly increases to ∼75 nN at 95% of saturation vapor pressure. This increase in force is well within the capabilities of even the lowest force on-chip actuators, such as electrostatic comb drives which can typically generate a few μN of force. The static friction force was found to be independent of alcohol vapor pressure within the uncertainties in the measurement.