<![CDATA[Casimir interactions increasingly influence the stability of micro-electromechanical systems as device separations approach the nanoscale, yet their force fluctuations and rotational effects remain insufficiently integrated into topological-insulator device design. This study aimed to quantify Casimir force fluctuations, evaluate tunable Casimir torque, and identify mechanically stable operating regimes for topological-insulator-based micro-electromechanical systems. A theoretical-computational framework combined finite-temperature Lifshitz theory, scattering-matrix calculations, fluctuation–dissipation analysis, coupled translational–torsional mechanics, and Monte Carlo uncertainty propagation across 10,000 parameter configurations. Results showed that accepted topological-insulator configurations generated a median torque of 3.84 pN·µm and median torque modulation of 36.8%, while maintaining a lower median normal force than gold-coated references. Stable equilibria occurred in 84.8% of configurations. Separations of 100–250 nm and film thicknesses of 20–60 nm provided the most favorable compromise between torque enhancement and pull-in resistance. Magnetic surface gap and anisotropy increased torque tunability, whereas narrow gaps and elevated temperatures amplified force fluctuations and instability risk. The findings demonstrate that topological surface responses can support controllable, contactless rotational behavior when electromagnetic tunability is evaluated alongside mechanical stability. Stable fluctuation-adjusted torque, rather than maximum nominal torque, should guide the design of future quantum-enabled micro-electromechanical resonators, angular sensors, and low-power actuators under realistic material and geometric uncertainties.]]>
