Solutions for friction reduction at nano/microscale for MEMS actuators-based devices

Micro-Electro-Mechanical Systems (MEMS) are miniaturized devices built at nano/micro-scale. MEMS are fabricated from semiconductor silicon. At nano/micro-scale, capillary force along with asperity deformation induces friction at the surfaces of moving elements of actuators-based devices. The magnitude of friction force so generated is of the same order as that of the forces driving the moving elements. Friction therefore resists the relative mechanical motion between moving elements and reduces the useful operating lifetime of actuator devices. Solutions to reduce friction at nano/micro-scale in silicon by surface modification include: (i) chemical modification i.e. thin lubricant films/coatings, (ii) topographical modification i.e. surface patterning and (iii) hybrid modification, i.e. combination of topographical and chemical modifications. Friction behavior at nano/micro-scale of silicon and modified silicon surfaces is presented and discussed in this paper. Amongst the different surface modification approaches, the hybrid modification shows the best results in terms of friction reduction.