A torsional pendulum, built by researchers in Stuttgart and Montpellier, uses a single carbon nanotube as the torsional spring.

The device, which uses a gold and chromium block with a mass of 2x10^-16kg, has a moment of inertia of 7x10^-30kgm² with respect to the tube axis. The diameter of the single-walled carbon nanotube is 1.5nm, and the pendulum can be turned through one degree by a torque of 5x10^-20Nm.

Resonant frequency is calculated to be 100kHz. Deflection is achieved by electric field, and the moving part returns to its initial position even after 180 degree rotation.

This sensitivity means that thermal excitations of the pendulum cause torsional oscillations.

Making the device involved growing nanotubes, e-beam depositing the metal structures, then cutting and etching away the supporting wafer.