A Characterization System for Microwave Sensing and Heating over Individual Nanoliter-sized Droplets

基于液滴的微流控平台具有巨大的潜力，可以在材料合成、生命科学研究、食品安全控制和药物发现等多个领域的现有分析水平上发生革命性的变化。由于在单个液滴一级缺乏强大的液滴操作功能，它们作为高通量分析的一种使能技术被业界广泛采用在很大程度上受到了阻碍。同时传感和加热单个纳升大小的液滴，这是使此类平台真正发挥作用的关键特征之一，但实现这一点具有挑战性。该项目建议开发一种新的微波技术来应对这一挑战。水和油是在微流控平台中制造液滴的常用不相容流体，也被用于任博士的液滴微流体学研究，水和油之间的介电特性差异可能会导致微波工作频率的变化。这种频移可用于检测液滴的存在。如果以与特定液滴相关的频率输送电力，那么只有这个液滴接收能量，而周围的油流不受影响。这种机制允许在没有外部触发的情况下对单个液滴同时进行传感和加热。为了表征所提出的微波技术的传感和加热性能，迫切需要一种系统来精确测量高速微波的频率，在较宽的频段向微波单元供电，并对液滴的温度进行量化。该系统应由矢量网络分析仪(VNA)、射频信号发生器、配有CCD摄像机的显微镜和PC机组成。由于安装了倒置显微镜(GX71，奥林巴斯)，所要求的系统包括VNA、信号发生器、与GX71显微镜兼容的CCD摄像机和PC。该系统不仅将为任博士的研究项目提供急需的分析资源，还将作为她的总部人员的培训平台，通过任博士与所要求的系统支持的广泛领域的领先研究人员的合作，获得多学科经验。

Droplet-based microfluidic platforms have tremendous potential to revolutionize the current levels of analysis in a variety of fields such as material synthesis, life science research, food safety control and drug discovery. Their wide adoption by the industry as an enabling technology for high throughput analysis has been largely hindered due to the lack of robust functions for droplet manipulation at the single droplet level. Simultaneous sensing and heating of individual nanoliter-sized droplets, which is one of the key features to make such platforms truly functional, is challenging to achieve. This project proposes to develop a novel microwave technology to address this challenge. The disparity in dielectric properties between water and oil, which are the commonly used immiscible fluids to make droplets in microfluidic platforms and are also employed in Dr. Ren's droplet microfluidics research, can cause a shift in the microwave's operating frequency. This frequency shift can be used for sensing droplet presence. If power is delivered at the frequency associated with a particular droplet, then only this droplet receives energy leaving the surrounding oil streams unaffected. Such a mechanism allows simultaneous sensing and heating over individual droplets without external triggers. In order to characterize the sensing and heating performance of the proposed microwave technology, a system is urgently needed to accurately measure the frequency of microwaves at a high speed, supply power to the microwave unit at a wide frequency band and quantify the temperature of droplet. Such a system should consist of a vector network analyzer (VNA), a radio frequency signal generator, a microscope equipped with a CCD camera and a PC. Because an inverted microscope (GX71, Olympus) is in place, the requested system includes a VNA, a signal generator, a CCD camera compatible with the GX71 microscope and a PC. This system will not only provide urgently needed analytical resources to Dr. Ren's research programs, but also serve as a training platform her HQPs to receive multidisciplinary experiences through Dr. Ren's collaborations with leading researchers in a wide range of fields enabled by the requested system.