Macro‐Scale Electrostatic Comb‐Drive Actuator for Precision Millinewton‐Force Calibration

ABSTRACT

This paper presents the design, analytical modelling, finite‐element simulation and experimental validation of a macro‐scale electrostatic comb‐drive actuator optimised for precision force calibration in the millinewton range. The actuator features interdigitated aluminium fins fabricated by conventional machining, enabling precise control of electrostatic force generation. A multi‐fidelity characterisation approach is adopted, combining closed‐form analytical models, three‐dimensional (3D) electrostatic simulations in ANSYS Maxwell and high‐precision experimental measurements. Comprehensive parametric analyses evaluate the effects of fin number, overlap length, applied voltage, fin geometry and parallel‐array configuration on force output. Experimental results obtained over an applied voltage range of 320–1400 V show excellent agreement with simulation predictions, with maximum deviations below 9%. In contrast, the closed‐form analytical model exhibits larger deviations of up to 26%–28% relative to the FEM and experimental results, respectively. Experimental and FEM results confirm that force magnitude scales directly with overlap length, while FEM simulations indicate a similar direct scaling with increased fin number. Reduced inter‐fin spacing enhances force generation but increases the risk of dielectric breakdown. Tapered fin profiles produce elevated local electric field intensities yet yield lower total force than rectangular fins due to reduced effective overlap area. Numerical results further predict that a parallel arrangement of compact actuators achieves linear force scaling without added fabrication complexity. The actuator was successfully integrated into a torsional balance system, demonstrating reliable calibration against reference millinewton‐level loads. This work extends established comb‐drive actuation principles from the micro‐ to the millimetre scale, establishing a cost‐effective, room‐temperature platform for high‐accuracy force metrology.