Characterizing Fluid Properties for Micro/Nano Droplet Using High-Q Whispering Gallery Modes

使用高 Q 回音壁模式表征微/纳米液滴的流体特性

• 批准号: 1438112
• 负责人: Sunny Jung
• 金额: $ 37.16万
• 依托单位: Virginia Polytechnic Institute and State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-09-01 至 2017-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1438112&HistoricalAwards=false
• 关键词: Characterizing; Fluid; Properties; Micro; Nano

CBET 1438112This project aims to develop a new method to measure the fluid properties of tiny liquid droplets by using light to deform the shape of the drop. The method involves using a laser and an optical fiber to inject photons into the drop. These photons form a whispering gallery mode, which is an optical wave that is reflected by the droplet interface and circulates near the equator of the drop. The radiation pressure from the optical wave causes the interface to bulge, which, in turn, causes a change in the frequency of the whispering gallery mode. By detecting the change in frequency, extraordinarily small changes in the shape of the drop can be measured. These shape changes can then be used to deduce the surface tension of the fluid interface and the viscosity of the internal fluid. There are no other comparable methods for measuring these properties in micron-size drops. Thus, the project will provide scientists and engineers with a new tool for measuring physical properties that can be applied to colloidal systems, emulsions, aerosols and other suspensions that are formed in many manufacturing processes and biological systems.The presence of high-Q whispering gallery modes within the liquid drops will be established through optical spectrum measurements. The optical force that induces drop deformation will be experimentally confirmed and characterized. Drop deformation will be determined by measuring shifts in the whispering gallery mode resonance frequency. Results will be verified by measuring deformation with white light interferometry that is capable of detecting interface movement with nanometer scale resolution. The roles of surface tension and viscosity will be investigated by comparing the measured drop deformation and rate of deformation with boundary element solutions of the Stokes equations for the drops. Experiments will be carried out using simple fluids such as water and silicone oils. A system consisting of nanoparticles suspended in liquid will be characterized to simulate whispering gallery mode induced drop deformation in a more complex fluid.

这个项目旨在开发一种新的方法，通过光来改变液滴的形状来测量微小液滴的流体特性。该方法包括使用激光和光纤将光子注入液滴。这些光子形成了一个窃窃私语的走廊模式，这是一种被液滴界面反射并在液滴赤道附近循环的光波。来自光波的辐射压力导致界面凸起，这反过来又导致耳语通道模式频率的变化。通过检测频率的变化，水滴形状的微小变化就可以被测量出来。这些形状的变化可以用来推断流体界面的表面张力和内部流体的粘度。没有其他可比较的方法来测量微米大小的液滴的这些特性。因此，该项目将为科学家和工程师提供一种测量物理特性的新工具，该工具可应用于许多制造过程和生物系统中形成的胶体系统、乳液、气溶胶和其他悬浮液。通过光谱测量，将确定液滴内部存在高q窃窃廊模式。引起水滴变形的光力将被实验证实和表征。水滴变形将通过测量窃窃私语走廊模式共振频率的位移来确定。结果将通过白光干涉测量法测量变形来验证，白光干涉测量法能够以纳米尺度分辨率检测界面运动。通过将液滴的变形和变形速率与Stokes方程的边界元解进行比较，将研究表面张力和粘度的作用。实验将使用水和硅油等简单流体进行。一个由悬浮在液体中的纳米颗粒组成的系统将被表征为模拟在更复杂的流体中引起的耳语廊模式滴变形。