CAREER: Electrohydrodynamic Coulter Counting

Duke University, Durham NC

Investigators

Abstract

0846705 Chen A 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.