Measurements for load capacitance of fluid film lubrication with diffused electric double layer

除低速外，流体动力润滑具有减摩的作用。由于分子引力(即范德华力)在微纳系统中起主导作用，流体动力负载电容不足以避免低速条件下表面之间的直接接触。“Stiction”就是一个例子。开发新的MEMS液体润滑机理具有重要意义。首席研究员提出了一种使用双电层的新机制。利用扫描探针显微镜(SPM)测量了负载电容，考察了探针半径、外加电压、离子种类、离子浓度、表面间距等因素对负载电容的影响，并对SPM进行了改进，使其适用于测量液体中的法向力和摩擦力。用溅射沉积的10 nm金膜在探头顶端粘贴了一层球形的环氧树脂。离子液体已经被使用，它是未来润滑的候选对象。研究了在10~150 mV电压范围内测得的排斥力特性。

Hydrodynamic lubrication has the effect of reducing friction except at a low speed. Since molecular attractive force (i.e. van del Waals force) has been predominant effect in micro-nanoscopic system, hydrodynamic load capacitance has not been enough to avoid direct contact between surfaces in low velocity condition. "Stiction" is an example. It is important that development of new lubrication mechanism for MEMS in liquid. Head investigator proposed a new mechanism using electric double layer. It was simulated numerically as result that repulsive force has been taken effect at 10 to 100 nanometers gap between surfaces.In this study, load capacitance has been measured by SPM (Scanning Probe Microscope), for influences of probe radius, applied voltage, kind and concentrations of ion and distance between surfaces for consideration of ability of nano-lubrication by electrical double layer.SPM has been modified for measurements of normal and frictional force in liquid. A spherical epoxy resin has been pasted at the top of probe tip with sputter-deposited 10nm Au film. Ionic liquid, which is candidate for future lubrication, has been used. Characteristics of repulsive force measured at 10 to 150 mv voltage have been investigated.