溶液环境中利用声学、磁力、光热和静电力驱动微悬臂的动力学分析比较

Dynamics comparation of microcantilevers driven by acoustics,magnetics, photothermal and electrostatics in liquids

原子力显微镜(Atomic force microscopy,AFM)是用来获得样品表面微观信息的重要工具,在液相下振动模式中(Dynamic mode)悬臂振动参数如品质因子Q、振动频谱响应等对能否稳定成像及精确测量起着关键性作用。目前最普遍的驱动方式是声学振动-用压电陶瓷来间接驱动悬臂振动,然而此方法固定悬臂的液体槽和水溶液的耦合作用会产生杂峰,从而影响悬臂正常工作,降低成像品质。因此研究者们发展了各种不同的方法来直接对悬臂进行驱动。本文综合现有的利用声学、磁力、光热和静电力等不同的微悬臂驱动方法,分析、比较这几种方法所产生的振幅和相位响应及应用于振动模式AFM中的优劣,可为研制更高分辨率的AFM提供参考。

Background： Dynamic atomic force microscopy has become a powerful tool for the nanoscale imaging of biological samples. In solution, the cantilever oscillation parameters such as quality factor and frequency response are critical for stable imaging and precise measurements. The commonly driving cantilever method is acoustical-piezoelectrical approach. However, this indirect excitation mechanism will induce many spurious resonance peaks due to the hydrodynamic interaction between the fluid cell and the liquid in solution, which produce an unstable oscillation of the cantilever. Purpose： Drive the cantilever in a direct way to obtain a well controlled oscillation. Methods： Several direct driving techniques have been successfully developed such as magnetic, electrostatic, acoustical and photothermal excitations. Results： There is a single resonance peak in the cantilever oscillation spectrum under liquid environment with these direct driving methods. Conclusions： Several methods can directly drive the cantilever including magnetic, electrostatic, acoustical and photothermal excitations. The amplitude and frequency response with these different methods is compared.