Kim Il Kwang, Lee Soo Il
J Nanosci Nanotechnol. 2016 May;16(5):4362-9. doi: 10.1166/jnn.2016.11024.
The modal decomposition of tapping mode atomic force microscopy microcantilevers in liquid environments was studied experimentally. Microcantilevers with different lengths and stiffnesses and two sample surfaces with different elastic moduli were used in the experiment. The response modes of the microcantilevers were extracted as proper orthogonal modes through proper orthogonal decomposition. Smooth orthogonal decomposition was used to estimate the resonance frequency directly. The effects of the tapping setpoint and the elastic modulus of the sample under test were examined in terms of their multi-mode responses with proper orthogonal modes, proper orthogonal values, smooth orthogonal modes and smooth orthogonal values. Regardless of the stiffness of the microcantilever under test, the first mode was dominant in tapping mode atomic force microscopy under normal operating conditions. However, at lower tapping setpoints, the flexible microcantilever showed modal distortion and noise near the tip when tapping on a hard sample. The stiff microcantilever had a higher mode effect on a soft sample at lower tapping setpoints. Modal decomposition for tapping mode atomic force microscopy can thus be used to estimate the characteristics of samples in liquid environments.
对液体环境中轻敲模式原子力显微镜微悬臂梁的模态分解进行了实验研究。实验中使用了不同长度和刚度的微悬臂梁以及两个具有不同弹性模量的样品表面。通过本征正交分解将微悬臂梁的响应模式提取为本征正交模态。采用平滑正交分解直接估计共振频率。从它们与本征正交模态、本征正交值、平滑正交模态和平滑正交值的多模态响应方面，研究了轻敲设定点和被测样品弹性模量的影响。无论被测微悬臂梁的刚度如何，在正常操作条件下，第一模态在轻敲模式原子力显微镜中占主导地位。然而，在较低的轻敲设定点下，柔性微悬臂梁在硬样品上轻敲时，尖端附近会出现模态畸变和噪声。在较低的轻敲设定点下，刚性微悬臂梁在软样品上具有更高的模态效应。因此，轻敲模式原子力显微镜的模态分解可用于估计液体环境中样品的特性。
