Abstract
In consideration of the presented optical-thermally excited resonant mass detection scheme, molecular dynamics calculations are performed to investigate the thermal actuation and resonant mass sensing mechanism. The simulation results indicate that an extremely high temperature exists in a 6% central area of the graphene sheet exposed to the exciting laser. Therefore, constraining the laser driving power and enlarging the laser spot radius are essential to weaken the overheating in the middle of the graphene sheet, thus avoiding being burned through. Moreover, molecular dynamics calculations demonstrate a mass sensitivity of 214 kHz/zg for the graphene resonator with a pre-stress of 1 GPa. However, the adsorbed mass would degrade the resonant quality factor from 236 to 193. In comparison, the sensitivity and quality factor could rise by 1.3 and 4 times, respectively, for the graphene sheet with a pre-stress of 5 GPa, thus revealing the availability of enlarging pre-stress for better mass sensing performance.
Highlights
Graphene-based nanoelectromechanical systems (NEMS) offer rich prospects for delicate sensing applications, including accelerometers [1], biomedical detection [2], and gas measurement [3]
Han et al [22] used molecular dynamics (MD) calculation to investigate the possibility of mass measurement based on the edge mode of graphene resonators, and the results showed that the mass sensitivity corresponding to the edge mode was about three times higher than that of the fundamental mode
Where ∆Q refers to the local heat flux; κ is the thermal conductivity; dT/dr is the temperature gradient; r is the radius to the center; h is the graphene sheet height, and 2πrh represents the cross-sectional area of heat flow
Summary
Graphene-based nanoelectromechanical systems (NEMS) offer rich prospects for delicate sensing applications, including accelerometers [1], biomedical detection [2], and gas measurement [3]. They found that the frequencies of graphene resonators decreased from 95 MHz to 90 MHz with the injection of a Hydrogen and Argon gas mixture, and the quality factor decreased from 45 to 15 These results indicated the possibility of graphene nanomechanical resonators for lightweight mass detection. Han et al [22] used MD calculation to investigate the possibility of mass measurement based on the edge mode of graphene resonators, and the results showed that the mass sensitivity corresponding to the edge mode was about three times higher than that of the fundamental mode. Other approaches using nonlinear vibration [23], introducing vacancies [24], and adjusting capacitive force [25] have been attempted to improve the performance of graphene-based resonant mass sensors Most of these investigations were focused on the relationship between resonant frequencies and adsorbed mass, rather than providing a systematic detection scheme. The degradation of the resonant quality factor caused by the adsorbed water molecules is observed, and the stronger pre-stress is proved to contribute to the improvement of both the quality factor and the sensitivity
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