Quantified Stress Relaxation in Carbon Nanotube Resonators

We report an in-depth study of a suspended carbon nanotube resonator over the time span of more than 80 days. The resonator carries multiple carbon nanotubes, of which two show distinguishable frequency responses at different frequencies. The eigenfrequencies of one carbon nanotube ranges from 105 MHz and decays down to 30 MHz over time, indicating internal pre-stress relaxation from 90 MPa down to 10 MPa. With the application of new approaches in the modelling of carbon nanotube resonance currents, it is possible to quantify the time evolution of the internal pre-stress and the nonlinear spring constant.