Self-Sensing WS Nanotube Torsional Resonators.

We demonstrate self-sensing tungsten disulfide nanotube (WS NT) torsional resonators. These resonators exhibit all-electrical self-sensing operation with electrostatic excitation and piezoresistive motion detection. We show that the torsional motion of the WS NT resonators results in a change of the nanotube electrical resistance, with the most significant change around their mechanical resonance, where the amplitude of torsional vibrations is maximal. Atomic force microscopy analysis revealed the torsional and bending stiffness of the WS NTs, which we used for modeling the behavior of the WS NT devices. In addition, the solution of the electrostatic boundary value problem shows how the spatial potential and electrostatic field lines around the device impact its capacitance. The results uncover the coupling between the electrical and mechanical behaviors of WS and emphasize their potential to operate as key components in functional devices, such as nanosensors and radio frequency devices.