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NANOSCALE CHARGE DENSITY MEASUREMENT IN LIQUID WITH AFM

LI, LI
http://rave.ohiolink.edu/etdc/view?acc_num=case1599744539112356

Abstract Details

2020, Doctor of Philosophy, Case Western Reserve University, Biomedical Engineering.
Surface charge density is one of the most important properties to understand and predict behaviors of nanoscale objects in fluid. The ability to measure the surface charge density in fluid is valuable in various fields. In the field of nanoparticle synthesis, it accelerates the systematical alternations of the design of the nanoparticles to control their in-vivo behavior. In the field of bone material designing, it facilitates unveiling the mechanism of collagen molecule self-assembly. Thus, a method to quantitatively measure nanoscale surface charge density in fluid is needed. However, current charge density measuring techniques can not fulfill these requirements. In this dissertation, we provide solutions to this problem using the Atomic Force Microscopy (AFM). Current AFM charge measurement methods are low-resolution and only qualitative due to the experimental operation method and the unknown charge on the tip. To improve resolution, a polarizable dielectric tip without externally applied voltage is brought to physical contact with the sample, and the near-contact region of the collected force curve is used to obtain sample charge density. The interaction between tip and sample is reconstructed using theory that includes: electrostatic interactions, dipolar interactions, screening from both the dielectric screening of water and solvated ions, drag viscosity, and hardcore repulsion. To be quantitative, the charge density of the tip is experimentally calibrated using tobacco mosaic virus. To show application of the charge-calibrated tip, the surface charge densities on 20 individual charged beads are measured. The average of these AFM-measured bead charge densities is compared with the value calculated from titration experiments. The two values are found to agree within 20%.
Steven Eppell (Advisor)
Fredy Zypman (Advisor)
Daniel Lacks (Committee Member)
Roger French (Committee Member)
Efstathios Karathanasis (Committee Chair)
Biomedical Engineering

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Citations

  • LI, L. (2020). NANOSCALE CHARGE DENSITY MEASUREMENT IN LIQUID WITH AFM [Doctoral dissertation, Case Western Reserve University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=case1599744539112356

    APA Style (7th edition)

  • LI, LI. NANOSCALE CHARGE DENSITY MEASUREMENT IN LIQUID WITH AFM. 2020. Case Western Reserve University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=case1599744539112356.

    MLA Style (8th edition)

  • LI, LI. "NANOSCALE CHARGE DENSITY MEASUREMENT IN LIQUID WITH AFM." Doctoral dissertation, Case Western Reserve University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=case1599744539112356

    Chicago Manual of Style (17th edition)

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© 2020, all rights reserved.
This open access ETD is published by Case Western Reserve University School of Graduate Studies and OhioLINK.