Microsliding

Microsliding is the relative sliding motion between contacting surfaces at micrometer or smaller dimensions, a regime commonly encountered in microelectromechanical systems (MEMS), nanoelectromechanical systems (NEMS), and precision micropositioning devices. In this scale, surface forces such as adhesion and capillarity become comparable to or dominate elastic and inertial effects, producing friction, wear, and stiction behaviors that differ from macroscopic sliding.

Key factors include scale-dependent contact mechanics, surface roughness, and material properties. Contact may involve isolated asperities or continuous interfaces, and adhesion can cause permanent sticking (stiction). Friction coefficients can vary with speed, load, humidity, and temperature, and may exhibit stick-slip or intermittent motion even at low velocities. Wear mechanisms include abrasive, adhesive, and corrosive processes, often accelerated by high surface-to-surface contact area relative to volume.

Measurement and modeling approaches combine microtribometry and atomic force microscopy lateral force measurements, interferometric displacement sensing, and torsional or radial sensors. Models range from adapted Hertzian theories with adhesion (JKR or DMT) to continuum tribology and atomistic simulations such as the Prandtl-Tomlinson framework for atomic-scale friction.

Materials and lubrication strategies for microsliding include silicon, silicon nitride, metals, ceramics, and coatings such as diamond-like carbon or fluorinated self-assembled monolayers. Ultrathin liquid or solid lubricants, graphene, and MoS2-based films reduce friction and wear; surface engineering aims to minimize stiction and control friction.

Applications span MEMS relays, microactuators, optical or scanning probes, and precision alignment stages. Challenges include controlling stiction, delivering reliable lubrication, and ensuring repeatable performance over environmental variations and long operating lifetimes.