Kim Younghun, Yi Jongheop
Department of Chemical Engineering, Kwangwoon University, 447-1, Wolgye, Nowon, Seoul 139-701, Korea.
J Phys Chem B. 2006 Oct 19;110(41):20526-32. doi: 10.1021/jp063591+.
The open liquid-cell atomic force microscope (AFM) has potential for studies of biomaterials and surface morphology in liquid media, and a variety of fluids can be used as buffer solutions. The dependence of image distortion on fluid properties (kinematic viscosity) has been studied with edge friction force obtained in lateral images and will shortly appear elsewhere [Appl. Phys. Lett. 2006, 88, 173121]. Previous studies indicate that the scan rate should be slower for obtaining a nondistorted image. However, the time required for the scan is greatly increased. Therefore, we introduced the vector concept to evaluate the net force for scanning in the y-direction and found two solutions to achieve a zero force difference introduced by the cantilever-fluid and the tip-surface. When the scan rate approaches zero or a specific velocity (30 microm/s in this study), the force of the interaction induced by the cantilever-fluid and tip-surface is reduced to a considerable extent. Among the two solutions, a scan with a specific velocity is an easy, rapid method for obtaining a nondistorted image, compared to the previously proposed method (scan rate approaches zero). This proposed model was confirmed in a proof-of-concept test using 2-propanol.
开放式液池原子力显微镜（AFM）在液体介质中研究生物材料和表面形态方面具有潜力，并且多种流体可作为缓冲溶液。已利用横向图像中获得的边缘摩擦力研究了图像畸变对流体性质（运动粘度）的依赖性，相关研究成果即将发表于其他地方[《应用物理快报》，2006年，第88卷，第173121页]。先前的研究表明，为了获得无畸变图像，扫描速率应较慢。然而，扫描所需的时间会大幅增加。因此，我们引入矢量概念来评估在y方向扫描的合力，并找到了两种方法来实现由悬臂 - 流体和针尖 - 表面引入的力差为零。当扫描速率接近零或特定速度（本研究中为30微米/秒）时，由悬臂 - 流体和针尖 - 表面引起的相互作用力会大幅降低。在这两种方法中，与先前提出的方法（扫描速率接近零）相比，以特定速度进行扫描是一种简便、快速获取无畸变图像的方法。该模型在使用异丙醇的概念验证测试中得到了证实。
