SBIR Phase I: Shear Stress Sensor Based on Optical Micro-Spring Technology

该小型企业创新研究第一阶段项目旨在开发一种以光学微弹簧(OMS)为核心元件的壁面剪应力传感器。OMS是一种基于光纤的微型称重传感器，它依赖于在微腔中实现的被称为语廊模式(WGM)的形态相关的光学共振。提出了一种小型、坚固耐用的传感器，可以直接测量透明或不透明介质中的壁面剪应力。由于WGM技术的高品质因数，可以检测到微小到百分之一纳米的传感元件的位移。因此，在检测剪切力的四个数量级以内的传感元件位移时，传感器实际上没有任何移动部件。该项目将促进对流动边界层中发生的基本过程的理解。对于非牛顿流体或其他复杂的流体，壁面剪应力不容易计算或测量，特别是对于非透明流动。化工和制药行业无法衡量和预测混合设备的性能。壁面剪应力的直接测量将显著改进现有的CFD模型，并提供一种手段来提高高强度混合设备的过程控制、质量和产量，并降低最终产品的成本。

This Small Business Innovation Research Phase I project is aimed at the development of a wall shear stress sensor with an Optical Micro-Spring (OMS) as its core element. The OMS, a miniature fiber-based load cell, relies on the morphology-dependent optical resonances known as Whispering Gallery Modes (WGM) realized in a microcavity. A miniature and robust sensor is proposed that is capable of direct measurement of wall shear stress in either transparent or opaque media. Due to high quality factor of WGM technology, displacements of the sensing element as small as a hundredth of a nanometer can be detected. The sensor therefore virtually does not have any moving parts while detecting sensing element displacements within more than four orders of magnitude of the shear force. The project will advance the understanding of the fundamental processes occurring in the boundary layer of a flow. For non-Newtonian or otherwise rheologically complex fluids the wall shear stress can not be easily calculated or, especially for non-transparent flows, measured. The chemical and pharmaceutical industries suffer from an inability to scale and predict mixing equipment performance. Direct measurements of wall shear stress would significantly improve existing CFD models and provide a means to increase process control, quality and throughput for high intensity mixing devices and to reduce the cost of the final product.