Large colloidal probes for atomic force microscopy: Fabrication and calibration issues
Large colloidal probes for atomic force microscopy: Fabrication and calibration issues
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DOI：
10.1002/jmr.2879
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发表时间：
2020-10-24
影响因子：
2.7
通讯作者：
Podesta, Alessandro
中科院分区：
文献类型：
--
作者：
Chighizola, Matteo;Puricelli, Luca;Podesta, Alessandro
原子力显微镜（AFM）是研究微观和纳米尺度相互作用力的有力工具。尖端的悬臂刚度、尺寸和几何形状可以根据具体应用的要求在空间分辨率和力灵敏度方面进行选择。胶体探针（CP），通过将球形颗粒连接到无尖端（TL）悬臂梁上获得，为精确的力测量提供了几个优点：可调和良好的表征半径;更高的平均能力（以空间分辨率为代价）和对弱相互作用的敏感性;定义良好的相互作用几何形状（平面上的球体），通过分析模型可以实现准确可靠的数据拟合。标准AFM探针的动力学已经被广泛研究，并且已经开发出用于校准悬臂弹簧常数的协议。然而，CP的动力学，特别是大CP，半径远高于10 μ m和质量相当，或更大，比悬臂质量，目前仍然很差的特点。在这里，我们描述的制造和校准（大）CP。我们描述和讨论的CP特有的动力学行为，并提出了一种替代协议的弹簧常数的准确校准。
Atomic force microscopy (AFM) is a powerful tool to investigate interaction forces at the micro and nanoscale. Cantilever stiffness, dimensions and geometry of the tip can be chosen according to the requirements of the specific application, in terms of spatial resolution and force sensitivity. Colloidal probes (CPs), obtained by attaching a spherical particle to a tipless (TL) cantilever, offer several advantages for accurate force measurements: tunable and well-characterisable radius; higher averaging capabilities (at the expense of spatial resolution) and sensitivity to weak interactions; a well-defined interaction geometry (sphere on flat), which allows accurate and reliable data fitting by means of analytical models. The dynamics of standard AFM probes has been widely investigated, and protocols have been developed for the calibration of the cantilever spring constant. Nevertheless, the dynamics of CPs, and in particular of large CPs, with radius well above 10 mu m and mass comparable, or larger, than the cantilever mass, is at present still poorly characterized. Here we describe the fabrication and calibration of (large) CPs. We describe and discuss the peculiar dynamical behaviour of CPs, and present an alternative protocol for the accurate calibration of the spring constant.