Electro-mechanical modelling and experimental characterization of a high-aspect-ratio electrostatic-capacitive MEMS device

•Short-range effects across small gaps in a high-aspect-ratio electrostatic-capacitive MEMS device are investigated.•The influence of surface separations and residual potential on MEMS behaviour including electrostatic pull-in are studied.•Comprehensive electro‑mechanical models for both static and dynamic regimes are developed and validated.•An extensive experimental characterization of the MEMS device is reported.•The extraction of mechanical and electrical parameters from the experimental data using the model is presented. As the typical surface separations in Micro Electro-Mechanical Systems (MEMS) are reduced to below one micrometer, detailed knowledge of the interaction forces down to this scale is required. In this context, we have developed a dedicated experimental platform to directly investigate electrostatic and physical effects in a high-aspect-ratio electrostatic-capacitive MEMS device based on commercial technology. In the present work, we report on an extensive experimental characterization, focused on the influence of the surface separations, electric surface potentials, and pressure on the static and dynamical behaviour of the device under precisely controlled conditions. For the proper analysis of the bias position and small‑displacement response of the device, we have developed a comprehensive electro‑mechanical model capable of describing the aforementioned effects, and allowing to extract the mechanical and electrical device parameters from the experimental data. Based on the developed model, a strong experimental evidence is found for significant variations in device characteristics upon reduction of surface separation to below one micrometer.