Zhang Guangjie, Li Peng, Wei Dawei, Hu Kui, Qiu Xiaohui
CAS Key Laboratory of Standardization and Measurement for Nanotechnology, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing 100190, People's Republic of China.
School of Science, Tianjin University, Tianjin 300072, People's Republic of China.
Nanotechnology. 2020 Nov 20;31(47):475703. doi: 10.1088/1361-6528/abae32.
Friction measurement via atomic force microscope (AFM) relies on accurate calibration for the torsional spring constant of the AFM cantilever and its lateral deflection sensitivity. Here we describe a method that employs a suspended nanowire (SNW) as a reference beam to quantify the torsional spring constant of AFM cantilevers. Based on the fact that a uniform SNW with cylindrical symmetry has an identical spring constant when bent in any direction perpendicular to its axis, the spring constant of the SNW in a normal direction is determined by an AFM cantilever with a known normal spring constant, and is subsequently used as a force transfer standard to calibrate the torsional spring constant of the AFM cantilever. The lateral deflection sensitivity can be accurately measured by pushing the AFM tip laterally on the groove edge. The calibration result is compared to the well-known diamagnetic lateral force calibrator method and shows an uncertainty of 15% or better. The presented method is applicable for the lateral force calibration of AFM cantilevers in a wide range of instruments including inverted configurations and in an ultrahigh vacuum.
通过原子力显微镜（AFM）进行摩擦力测量依赖于对AFM悬臂梁扭转弹簧常数及其横向偏转灵敏度的精确校准。在此，我们描述一种方法，该方法采用悬浮纳米线（SNW）作为参考梁来量化AFM悬臂梁的扭转弹簧常数。基于具有圆柱对称性的均匀SNW在垂直于其轴线的任何方向弯曲时具有相同弹簧常数这一事实，SNW在法线方向的弹簧常数由具有已知法线弹簧常数的AFM悬臂梁确定，并随后用作力传递标准来校准AFM悬臂梁的扭转弹簧常数。横向偏转灵敏度可通过在凹槽边缘横向推动AFM针尖来精确测量。校准结果与广为人知的抗磁横向力校准器方法进行了比较，显示不确定性为15%或更低。所提出的方法适用于包括倒置配置在内的各种仪器以及超高真空中AFM悬臂梁的横向力校准。
