We explore a new class of chipscale torsion pendula formed by ${\text{Si}}_3{\mathrm{N}}_4$ nanoribbon suspensions. Owing to their unique heirarchy of gravitational, tensile, and elastic stiffness, the devices exhibit damping rates of $\sim 10\mathrm{\mu }\mathrm{Hz}$ and parametric gravity sensitivities near that of an ideal pendulum. The suspension nonlinearity can also be used to cancel the pendulum nonlinearity, paving the way toward fully isochronous, high $Q$ pendulum gravimeters. As a demonstration, we study a 0.1 mg, 32 Hz micropendulum with a damping rate of $16\mathrm{\mu }\mathrm{Hz}$, a thermal acceleration sensitivity of $2\times {10}^{-9}{g}_0/\sqrt{\mathrm{Hz}}(g_0=9.8\mathrm{m}/{\mathrm{s}}^2)$, and a parametric gravity sensitivity of $5\mathrm{Hz}/g_0$. We record Allan deviations as low as $2.5\mathrm{\mu }\mathrm{Hz}$ at 100 seconds, corresponding to a bias stability of $5\times {10}^{-7}{g}_0$. We also demonstrate a 100-fold cancellation of the pendulum nonlinearity. In addition to inertial sensing, our devices are well suited to proposed searches for new physics exploiting low-loss micro- to milligram-scale mechanical oscillators.

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• Force sensing
• Optomechanics
• Micromechanical & nanomechanical oscillators
• Micromechanical devices
• Nano-oscillators
• Nanomechanical devices
• Noise measurements
• Precision measurements
• Weak measurements