A nanomachined torque sensor with ultrahigh sensitivity

This paper reports, for the first time, a novel nanoscale torque sensor in a split ring resonator. The mechanical resonator is embedded into ring resonator and separated by 200 nm from the substrate. By taking advantage of extreme sensitivity of ring resonator, the torque sensor achieves a displacement noise floor of 80 fm/ Hz05. This is corresponding to small torque as small as 0.17×10-18 Nm. Particularly, the platform can be used to investigate the dispersive and dissipative coupling in optomechanics for novel physical devices and opens new door for a wide range of physical measurements involving extremely small torques.