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

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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.