Equipment Proposal: Integrated Optical Force and Near-Field Scanning-Probe Microscope for Polymer Interfaces

摘要本项目申请的资金将用于构建扫描光学显微镜的光镊探针，并在仪器上增加动态光散射外围设备。由此产生的光学力显微镜将用于研究聚合物在固液界面上产生的力，并开发测量聚合物层动态顺应性的技术。所要求的添加将增强基本仪器的能力，以便可以研究一些相关问题，例如油-表面活性剂-水界面的机械响应和单链聚合物的荧光显微镜。这项拨款的总体目标是在显微镜中加入一种“光学操纵”小颗粒的装置。一个紧密聚焦的激光束训练在一个小粒子上，人们可以利用光束产生的力来操纵和移动这个粒子。这种“激光镊子”与扫描光学显微镜的结合使得人们可以使用光学持有的粒子作为“探针”来研究表面上的局部相互作用。握住粒子的激光束就像一个无形的弹簧作用在粒子上，通过调节激光功率可以很容易地改变这个“弹簧”的刚度。因此，光学探针允许人们研究非常柔软的表面，如表面上的聚合物链或液/液界面。这为研究聚合物层、单链、界面表面活性剂等的力学和动力学特性开辟了新的途径。这种现象的影响延伸到工程和科学中的许多重要问题，例如生物和药物分散体的稳定性，聚合物与生物医学表面的相容性，以及涉及颗粒的环境分离过程。

NSF CTS 0083258Equipment Proposal: Integrated Optical-Force and Scanning-Probe MicroscopeRaj Rajagopalan, University of FloridaAbstractThe funds requested through this proposal will be used to construct an optical-tweezer-probe for a scanning optical microscope and to add dynamic light scattering peripherals to the instrument. The resulting optical force microscope will be used to study polymer-induced forces at solid-liquid interfaces and to develop techniques for measuring dynamic compliance of polymer layers. The requested additions will enhance the capability of the basic instrument so that a number of related problems, such as mechanical response of oil-surfactant-water interfaces and fluorescent microscopy on single polymer chains, can be studied.The overall objective of this grant is to incorporate a device for "optical manipulation" of small particles in a microscope. A tightly focused laser beam trained on a small particle allows one to manipulate and move the particle using the forces generated by the light beam. The combination of such a "laser tweezer" with a scanning optical microscope allows one to use the optically held particle as a "probe" to study local interactions on a surface. The laser beam holding the particle behaves like an invisible spring on the particle, and the stiffness of this "spring" can be changed easily by adjusting the laser power. Therefore, the optically held probe allows one to study very soft surfaces such as polymer chains on a surface or a liquid/liquid interface. This opens up new ways to study the mechanical and dynamic properties of polymer layers, single polymer chains, surfactants at interfaces, and the like. The implications of such phenomena extend to a number of important problems in engineering and the sciences, such as stability of biological and pharmaceutical dispersions, polymer compatibility with biomedical surfaces, and environmental separation processes involving particulates.