CAREER: Electrohydrodynamic Coulter Counting

ChenA Coulter计数器通过一个小的流体孔径调制电流来检测和表征颗粒。本研究希望利用电流体动力学（EHD）锥射流建立库尔特计数的新范式，并展示该技术在定量和部署从生物大分子到合成纳米颗粒等纳米尺度物体方面的潜力。电阻式纳米孔传感是利用生物或合成纳米孔进行库尔特计数的小型化产物。现代的纳米孔传感器通常具有固定的直径，并且要么寿命短，要么可重复性低。这些限制可以通过利用EHD锥形射流转换来克服，这种独特的现象允许从更大的现成喷嘴中产生可调谐的纳米级液体射流。为此，实验和分析工具将结合起来，以确定在微米和亚微米水平上可重复的EHD射流所需的条件。通过将库尔特计数与EHD锥射流相结合，一种用于部署纳米物体的放置技术将以前所未有的单粒子精度得到发展。本研究将解决以下与EHD库尔特计数技术发展相关的基本问题：纳米级EHD射流是否具有或不具有内在脉动，可重复产生和检测？是否可以用液体射流代替合成孔来完成库尔特计数？在EHD部署中能否实现单粒子精度？相关的实验和分析研究将揭示控制纳米级EHD射流动力学和稳定性的尺度规律，并建立EHD库尔特计数新技术的性能边界。EHD Coulter计数器的成功开发将使纳米颗粒（如药物胶囊和量子点）的分析能够在可调的长度范围内进行，而无需借助标记，并且可以部署具有单分子精度的大分子，用于蛋白质纳米阵列和体外区室化。基于这项研究，PI将开发一门新的微尺度物理化学流体动力学研究生课程，并将通过普拉特研究员和杜克大学的NSF REU项目培养本科生研究人员。PI将从南方工程学院（Southern School of Engineering）招募一名教师进行两个暑期实习。南方工程学院是一所提供工程预科课程的高中，主要招收非裔美国人。该教师将参与构建EHD库尔特计数器的原型，并培训大学生在高中水平上交流科学思想，然后在PI的协助下，将最先进的微流体研究知识转移到高中水平的课程单元中，支持北卡罗来纳标准课程的学习。

0846705 ChenA Coulter counter detects and characterizes particles by the modulation of electrical current through a small fluidic aperture. This study hopes to establish a new paradigm of Coulter counting using electrohydrodynamic (EHD) cone-jets, and demonstrate the potential of this technique in quantifying and deploying nanoscale objects ranging from biological macromolecules to synthetic nanoparticles. Resistive nanopore sensing is a miniaturized descendent of Coulter counting using biological or synthetic nanopores. Contemporary nanopore sensors typically have fixed diameters and suffer from either short life spans or low reproducibility. These limitations can be circumvented by exploiting the EHD cone-jet transition, a unique phenomenon that permits production of tunable nanoscale liquid jets from much larger nozzles off-the-shelf. To this end, experimental and analytical tools will be combined to identify conditions required for reproducible EHD jets at both micron and sub-micron levels. By integrating Coulter counting with EHD cone-jets, a drop-and-place technique for deploying nano-objects will be developed with unprecedented single-particle accuracy. This study will address the following fundamental questions associated with the development of the EHD Coulter counting technique: Can nanoscale EHD jets, with or without intrinsic pulsations, be reproducibly generated and detected? Can a liquid jet be used in lieu of a synthetic pore to accomplish Coulter counting? Can single-particle accuracy be achieved in EHD deployment? The interrelated experimental and analytical investigations outlined in the study will reveal scaling laws governing the dynamics and stability of nanoscale EHD jets, and establish the performance boundary of the new technique of EHD Coulter counting. The successful development of an EHD Coulter counter would enable the analysis of nanoparticles such as drug capsules and quantum dots over a tunable range of length scale without resorting to labeling, and the deployment of macromolecules with single-molecule accuracy for protein nanoarrays and in vitro compartmentalization. Based on this research, the PI will develop a new graduate-level course in Microscale Physicochemical Hydrodynamics and will train undergraduate researchers through the Pratt Fellows and NSF REU programs at Duke University. The PI will recruit a teacher for two summer internships from the Southern School of Engineering, a high school that offers a pre-engineering program with a predominant African American enrollment. This teacher will participate in building prototype EHD Coulter counters and in training university students to communicate scientific ideas at the high school level and then, assisted by the PI, transfer the knowledge in state-of-the-art microfluidics research into a high school level curricular unit that supports the North Carolina Standard Course of Study.