MRI: Development of a Colloidal Force-Distance-Adsorption Apparatus for Particle Science Research and Education

弗吉尼亚理工学院和州立大学将利用这项来自主要研究仪器项目的奖金，开发一种用于测量胶体力的新实验工具。对这些力量的理解在材料科学、细胞生物学、土壤科学、废物处理和水净化、陶瓷工程、个人产品的开发以及微电子工业的质量控制中都是重要的。该仪器将结合原子力显微镜（AFM）和全内反射显微镜（TIRM）的能力，同时克服了每种技术的大多数缺点。该仪器将提供一种新的能力：测量粒子碰撞过程中的吸附等温线的能力。原子力显微镜是目前应用最广泛的胶体力测量方法。这种应用的一个主要问题是无法测量颗粒和表面之间的分离；它是间接推导出来的。使用该装置，分离将直接从由激光光束在衬底/流体界面上完全反射产生的倏逝波的散射强度中获得。这种方法基于TIRM技术。通过对散射的倏逝波进行调制，可以改进TIRM技术。物质对表面的吸附是调节胶体力的主要方法，因此在粒子相互作用过程中测定吸附是有用的。我们将开发一种技术来测量碰撞过程中的吸附使用荧光标签的吸附剂。研究生和本科生将参与该仪器开发项目。我们在日常生活中遇到的许多物体实际上都是由非常细小的粒子组成的。例如，砖、纸、衣服、瓷器、土壤、大多数食物、化妆品，甚至人类都是由小颗粒组成的。这些物体的物理性质（如刚度、流动性和可加工性）取决于粒子之间的作用力。创造新产品和改进产品的部分过程是操纵颗粒之间的力以获得理想的材料性能。操纵这些力的第一步是测量它们。弗吉尼亚理工学院和州立大学将利用这项来自主要研究仪器项目的奖金，开发一种新的实验工具，用于测量作用于粒子的力。新的仪器将结合现有的技术，原子力显微镜的力探针和全内反射显微镜的距离探针，并通过使用信号调制和分子荧光标记进行改进。本仪器开发项目将由一名研究生和一名本科生参与。

With this award from the Major Research Instrumentation program Virginia Polytechnic Institute and State University will develop a new experimental tool for measuring colloidal forces. An understanding of these forces is important in materials science, cell biology, soil science, waste disposal and water purification, ceramic engineering, the development of personal products, and in quality control in the microelectronics industry. The instrument will combine capabilities of atomic force microscopy (AFM) and total internal reflection microscopy (TIRM), while overcoming most of the drawbacks for each technique. The instrument will provide a new capability: the ability to measure adsorption isotherms during particle collisions. The atomic force microscope is currently the most widely used method for measuring colloidal forces. A major problem with this application is that the separation between the particle and the surface is not measured; it is derived indirectly. With this apparatus, the separation will be obtained directly, from the scattering intensity from an evanescent wave produced by totally reflecting a laser beam at the substrate/fluid interface. This approach is based on the TIRM technique. The TIRM technique will be improved through modulation of the scattered evanescent wave. The adsorption of material to surfaces is the main method by which colloidal forces can be modulated, so it is useful to determine adsorption during particle interactions. We will develop a technique for measuring adsorption during collisions using fluorescent tags on the adsorbates. Graduate and undergraduate students will participate in this instrument development project.Many of the objects that we encounter in everyday life actually consist of very fine particles. For example, bricks, paper, clothing, china, soil, most foods, cosmetics, and even humans are composed of small particles. The physical properties (e.g. stiffness, flow, and workability) of these objects depends on the forces between the particles. Part of the process of creating new and improved products is the manipulation of the forces between particles to obtain desirable material properties. The first stage of manipulating these forces is to measure them. With this award from the Major Research Instrumentation program Virginia Polytechnic Institute and State University will develop a new experimental tool for measuring the forces acting on particles. The new apparatus will combine existing techniques, the force probe from Atomic Force Microscopy and the distance probe from Total Internal Reflectance Microscopy, and incorporate improvements through the use of signal modulation and fluorescent tagging of molecules. A graduate student and undergraduate students will participate in this instrument development project.