A TORSION PENDULUM FOR CHIP-SCALE RELATIVE GRAVIMETRY

Pendulums were the original tool of gravimetry. Here, we introduce a new microscale platform aimed at this task that takes the form of a chip-scale torsion resonator. We derive a lumped parameter model for the physics of the device, illustrating that the torsional stiffness depends on gravity along with the material and internal stress of its thin-film nanoribbon torsion fiber. Dissipation dilution is introduced within the context of fundamental noise limits of detection, and its influence on design choices discussed. We provide proof of concept data from an “accidental” prototype, resolving a 20 % shift in the device frequency that occurs when inverted in the earth’s gravity to within a few parts in 10⁶. Our result suggests that a chip-scale gravimeter is achieved using nothing more sophisticated than an optical lever to read out the frequency of this resonator.