Figure 5.

(a–c) Internal resonance in a carbon nanotube (CNT) resonator [41]. (a) The coloured SEM image of the suspended CNT with the schematic side view of the system on the bottom. (b) Contour map of the resonant frequency as a function of gate voltage reaveals high-frequency tunability of CNT. (c) Frequency response plots at increasing gate voltages from left to right while AC voltages in gate and source electrodes are kept constant. The characteristic M-shaped resonance is observed when internal resonance is activated (symbol ○). (d–g) 2 : 1 internal resonance in an H-shaped resonator [68]. (d) SEM image of the H-shaped resonator with actuation and detection electrodes. (e) Experimental internal resonance curve at increasing forcing level. (f) Simulation results show the energy transfer between the two coordinate displacements, X and Y, due to internal resonance. (g) Amplitude saturation in the driven mode when internal resonance is triggered. (Online version in colour.)