Localized lubrication of micromachines: A feasibility study on Si in reciprocating sliding with PFPE as the lubricant

Abstract

The lubrication of Micro-Electro-Mechanical Systems (MEMS) has been a major obstacle to the micromachine industry, limiting the designs commercially available and actuating/sensing mechanisms in micro actuators/sensors to mostly non-contacting ones. MEMS are traditionally made of silicon (Si), which has very poor tribological properties. Lubrication techniques for MEMS usually involve highly expensive processes such as vapour deposition and complex hermetic packaging to ensure longer wear life. The present study proposes a novel method of locally delivering a required amount of lubricant onto a specific location on a MEMS device, extending its wear life by several orders of magnitudes. To study the feasibility of this process, a fixed amount of PFPE was delivered to a contact between two flat Si pieces which were then subjected to reciprocation sliding at an applied normal load of 0.5N and a sliding velocity of 5mms-1. Tribological properties such as coefficient of friction and wear behaviour were studied to ascertain the effectiveness of this lubrication method. The results have revealed that the current localized lubrication method is very effective in reducing the coefficient of friction and increasing wear life. © 2010 Elsevier B.V.