Xiao Xing, Fan Shang-Chun, Li Cheng, Xing Wei-Wei
School of Instrumentation and Optoelectronic Engineering, Beihang University, Beijing 100191, China.
Key Laboratory of Quantum Sensing Technology (Beihang University), Ministry of Industry and Information Technology, Beijing 100191, China.
Sensors (Basel). 2019 Jul 9;19(13):3027. doi: 10.3390/s19133027.
Herein, a peripherally clamped stretched square monolayer graphene sheet with a side length of 10 nm was demonstrated as a resonator for atomic-scale mass sensing via molecular dynamics (MD) simulation. Then, a novel method of mass determination using the first three resonant modes (mode11, mode21 and mode22) was developed to avoid the disturbance of stress fluctuation in graphene. MD simulation results indicate that improving the prestress in stretched graphene increases the sensitivity significantly. Unfortunately, it is difficult to determine the mass accurately by the stress-reliant fundamental frequency shift. However, the absorbed mass in the middle of graphene sheets decreases the resonant frequency of mode11 dramatically while having negligible effect on that of mode21 and mode22, which implies that the latter two frequency modes are appropriate for compensating the stress-induced frequency shift of mode11. Hence, the absorbed mass, with a resolution of 3.3 × 10 g, is found using the frequency ratio of mode11 to mode21 or mode22, despite the unstable prestress ranging from 32 GPa to 47 GPa. This stress insensitivity contributes to the applicability of the graphene-based resonant mass sensor in real applications.
在此，通过分子动力学（MD）模拟证明，边长为10纳米的周边夹紧拉伸方形单层石墨烯片可作为用于原子尺度质量传感的谐振器。然后，开发了一种使用前三个共振模式（模式11、模式21和模式22）进行质量测定的新方法，以避免石墨烯中应力波动的干扰。MD模拟结果表明，提高拉伸石墨烯中的预应力可显著提高灵敏度。不幸的是，通过依赖应力的基频偏移很难准确确定质量。然而，石墨烯片中间吸收的质量会显著降低模式11的共振频率，而对模式21和模式22的共振频率影响可忽略不计，这意味着后两个频率模式适用于补偿模式11的应力诱导频率偏移。因此，尽管预应力在32吉帕至47吉帕之间不稳定，但使用模式11与模式21或模式22的频率比仍可找到吸收质量，其分辨率为3.3×10克。这种对应力的不敏感性有助于基于石墨烯的谐振质量传感器在实际应用中的适用性。
