How Gaseous Environment Influences a Carbon Nanotube-Based Mechanical Resonator
YH Nie and HF Zhan and ZQ Zheng and AX Bo and E Pickering and YT Gu, JOURNAL OF PHYSICAL CHEMISTRY C, 123, 25925-25933 (2019).
Nanoscale mechanical resonator-based nanoelectromechanical systems have been reported with ultrahigh sensitivity, which are normally acquired from an ultravacuum environment at cryostat temperature. To facilitate their practical applications for gas sensing or bio-detection, it is critical to understand how the fluid (gas or liquid) environment will impact the resonance behaviors of the nanoresonator. This work reports a first-time comprehensive investigation on the influence of the N-2 gaseous environment on the resonance properties of carbon nanotube (CNT)-based mechanical resonator, through a combination of grand canonical Monte Carlo and large-scale molecular dynamics simulations. It is shown that the gaseous environment exerts a significant effect on the resonance properties of the CNT resonator through a dynamic desorption and readsorption process. Under the temperature of 100 K and the pressure of 1 bar, the displacement amplitude of the CNT resonator is found to experience a sharp reduction of about 82% within the first 90 ps vibration in the N-2 gaseous environment. Further, a large initial excitation is found to result in smaller adsorption and a reduced damping effect. For instance, when the excitation velocity amplitude increases from 2 to 8 angstrom/ps, the damping ratio shows more than 40% reduction. It is found that higher pressure leads to a smaller resonance frequency and enhanced damping effect, while higher temperature induces an increase in the resonance frequency but a decrease in the damping ratio. This work shows that the gaseous environment has a marked impact on the vibrational properties of nanoresonators, which should shed light on the application of mechanical nanoresonators in a fluid environment.
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