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

基于液滴的微流体平台具有巨大的潜力，可以彻底改变材料合成、生命科学研究、食品安全控制和药物发现等领域的当前分析水平。由于在单个液滴水平上缺乏用于液滴操作的稳健功能，它们作为高通量分析的使能技术被工业广泛采用在很大程度上受到阻碍。同时感测和加热单个纳升大小的液滴，这是使这种平台真正发挥作用的关键特征之一，实现起来具有挑战性。该项目提出开发一种新的微波技术来应对这一挑战。水和油是在微流体平台中制造液滴的常用不混溶流体，也用于Ren博士的液滴微流体研究，水和油之间介电特性的差异可能导致微波工作频率的变化。该频移可以用于感测液滴存在。如果以与特定液滴相关联的频率输送功率，则只有该液滴接收能量，而周围的油流不受影响。这样的机制允许在没有外部触发的情况下对单个液滴进行同时感测和加热。为了表征所提出的微波技术的感测和加热性能，迫切需要一种系统以高速精确地测量微波的频率，以宽频带向微波单元供电，并量化液滴的温度。该系统由矢量网络分析仪、射频信号发生器、带CCD摄像机的显微镜和PC机组成。由于倒置显微镜（GX 71，Olympus）已就位，因此所要求的系统包括VNA、信号发生器、与GX 71显微镜兼容的CCD相机和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，为她的HQP提供多学科经验。

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.