探索微纳尺度润湿动力学:长针式原子力显微镜的应用与进展

EXPLORE WETTING DYNAMICS AT MICRO AND NANO SCALES:APPLICATIONS AND PROGRESS OF LONG-NEEDLE ATOMIC FORCE MICROSCOPE

“如何在微观层面测量界面现象”是微纳尺度实验流体力学的关键科学问题,被列入世界前沿125个科学问题名单(Sanders S,Science,2021).由于光学衍射极限的限制,传统光学手段很难直接测量微纳尺度下的流动与界面现象.利用原子力显微镜的精准操控和小尺度力学测量等优势,结合长针式探针组装成的微流变计可以直接测量气-液-固三相接触线上的毛细力,并监测探针在垂直方向运动中力的动态变化.通过该技术手段,可以实现对流体界面的动力学行为以及各类材料在液体环境中力学性质在微纳尺度的精确表征.文章将系统介绍长针式原子力显微镜技术的实验原理和方法,及其在微纳尺度非理想界面润湿动力学中的最新研究进展,包括低能垒表面毛细力的速度依赖性与非对称性、无序粗糙表面接触线黏滑运动的统计学规律、柔性表面接触线动力学的状态与速度定律、以及离子液体-金属界面处电场对接触角迟滞的调控等,最后展望了该技术在新兴领域中的应用.该实验手段为检验各类理论模型与数值模拟提供了可信数据,为探究界面上复杂现象的物理本质提供参考.

“How can we measure interface phenomena on the microscopic level”is a key scientific question in microand nanoscale fluid mechanics and is also listed in recent 125 questions(Sanders S,Science,2021).Traditional optical methods face limitations due to the optical diffraction limit,making it difficult to directly measure flow and interfacial phenomena at micro-or nanoscale.However,atomic force microscopy(AFM)offers a solution by enabling precise manipulation and force measurements.The AFM-based microrheometer,which is assembled with a long-needle probe,can directly measure the capillary force acting at the gas-liquid-solid three-phase contact line,as well as the dynamic variations of forces during the vertical motion of the probe.This enables the precise characterization of the dynamic behaviors of fluid interfaces and the mechanical properties of various materials in liquid environments at micro-and nanoscales.In this paper,the experimental principles and methods of long-needle AFM will be reviewed,along with its latest progress in the study of wetting dynamics at the micro-and nanoscale non-ideal interfaces,including asymmetric and speed-dependent capillary force hysteresis on the surfaces with low energy barrier,avalanches and extreme value statistics of a moving contact line on disordered rough surfaces,state-and rate-dependent contact line dynamics over an aging soft surface,and manipulation of contact angle hysteresis at electrified ionic liquid-solid interfaces.This experimental method provides reliable data for testing various theoretical models and numerical simulations.The application of this technology in emerging fields may inspire us to explore the physical nature of complex phenomena at interfaces.