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Engineering Electromechanical Systems to Regulate Nanoscale Flows

Rangharajan, Kaushik Krishna
http://rave.ohiolink.edu/etdc/view?acc_num=osu1524140747281763

Abstract Details

2018, Doctor of Philosophy, Ohio State University, Mechanical Engineering.
This thesis focuses on exploring the role of electrical and mechanical forces, in regulating nanofluidic flows. At the nanoscale, surface area to volume ratio is high and ~O(109), implying surface properties such as surface charge and surface wettability can critically affect overall fluid and ion transport. In this dissertation, tapping mode atomic force microscopy was used to identify the morphological and line tension properties of interfacial nanobubbles formed on surfaces with varying degrees of hydrophobicity, as a function of gas super saturation state. Next, selective water vapor permeation through nanoscale air gaps (nanobubbles) was demonstrated by fabricating a nanofluidic platform with tunable hydrophobic patches to barricade flow of liquid water. By driving an osmotic distillation process in the transitional regime, the tangential momentum accommodation coefficient (TMAC), a fundamental parameter dictating momentum changes to a molecule colliding with a wall governing overall mass transport in Knudsen regime, was estimated experimentally. Additionally, two potential applications, namely: (1) extraction of usable water from hyper-saline 3 M and (2) separation of trace amounts of toluene, chloroform from water at high flux and selectivity were demonstrated. In addition to surface wettability dependent gas flows, the role of surface charge to modulate electrokinetic transport of aqueous solutions containing multiple ionic species in surface charge governed nanofluidic flows was investigated. Numerical models coupling steady state Poisson-Nernst-Planck and Stokes equations complemented with an experimental platform was developed to characterize electrokinetic transport inside nanocapillaries. The permselectivity of nanopores for a multi-component, multi-valent electrolyte were determined, and transport mechanisms were characterized based on the ion valence and background buffer concentration. The last section of this dissertation focusses on the role of electrical and fluid forces in regulating the vascular permeability of endothelial cells. Endothelial cells (ECs) lining blood vessels form a semi-permeable barrier, selectively allowing bidirectional transport of small molecules, ions, and fluid through sub – 20 nm inter-endothelial clefts. Here, an in vitro microfluidic analog of a branching blood vessel was fabricated to assess changes to vascular permeability under co-existing fluid mechanical (surface force) and electrical stimuli (body force). Morphological changes to EC ultrastructure due to application of electromechanical forces were characterized using electron microscopy and immunofluorescence staining.
Shaurya Prakash (Advisor)
Terry Conlisk (Committee Member)
Jonathan Song (Committee Member)
David Cole (Committee Member)
Jeffery Daniels (Committee Member)
291 p.
Biomedical Engineering; Mechanical Engineering; Nanoscience; Nanotechnology
Nanofluidics, Biomicrofluidics, Flow Control; Electromechanical Systems

Recommended Citations

Citations

  • Rangharajan, K. K. (2018). Engineering Electromechanical Systems to Regulate Nanoscale Flows [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1524140747281763

    APA Style (7th edition)

  • Rangharajan, Kaushik Krishna. Engineering Electromechanical Systems to Regulate Nanoscale Flows. 2018. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1524140747281763.

    MLA Style (8th edition)

  • Rangharajan, Kaushik Krishna. "Engineering Electromechanical Systems to Regulate Nanoscale Flows." Doctoral dissertation, Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1524140747281763

    Chicago Manual of Style (17th edition)

osu1524140747281763
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This open access ETD is published by The Ohio State University and OhioLINK.
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