原子力显微镜微悬臂梁品质因数的数字调控技术的研究

Digital Adjustment of AFM Microcantilevers' Quality Factor

为了提高轻敲模式原子力显微镜的微悬臂梁的低品质因数,在分析品质因数调控技术原理的基础上,设计了基于DSP的品质因数数字调控系统。该系统结构简单,操作方便,智能性和实时性好,能够比较精确地调控微悬臂梁振动的品质因数。通过对比液体中微悬臂梁振动的频谱以及蛋白质分子的成像实验证明,该数字调控电路能够提高微悬臂梁的力灵敏度,非常适合用于对软样品的检测。

The low quality factor （Q-factor） of microcantilever when operating an atomic force microscopy in tapping mode in liquid limits the instrument＇s resolution and sensitivity. By analyzing the Q-factor control theory, a module based on a DSP （digital signal processor） technique was developed to digitally tune the Q-factor of a microcantilever. The module has the advantages of simple structure, easy operation, fast feedback control and high Q-factor tuning precision. By comparing the frequency spectra of a microcantilever in liquid and protein molecule＇s images in butanol solution respectively, it is shown that the digital Q-factor tuning module can improve force sensitivity of the microcantilever and is suitable for testing soft samples.