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Rotational and Translational Dynamics of Silver and Titanium Dioxide Nanowires Suspended in Dielectric Media in Electric Fields

Farain, Kasra | 2018

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 51795 (04)
  4. University: Sharif University of Technology
  5. Department: Physics
  6. Advisor(s): Moshfegh, Alireza; Esfandiar, Ali
  7. Abstract:
  8. Wide utilization of nanomanipulation as a promising approach in microorganisms, nanoelectromechanical systems (NEMS) and assembly of nanostructures remarks the importance of nanostructures’ motion in electric fields. Despite of many reports on manipulation and assembly of nanowires (NWs) in non-uniform and alternating electric fields by dielectrophoresis, and also rotation of NWs in rotating electric fields, there is still a lack of knowledge on rotational and translational dynamics of metallic and dielectric NWs in uniform static electric fields. In this dissertation, we study the dynamics of silver (Ag) and titanium dioxide (TiO2) NWs, with diameters and lengths in the range of 40 to 100 nm and 4 to 40 μm, respectively, in a static uniform electric field in viscous dielectric liquids both theoretically and experimentally. For metallic NWs, it has been theoretically shown that the electric field-induced rotation is practically independent of the geometrical dimensions and electrical properties of NWs. Our experimental results for suspended Ag NWs in microscope oil are perfectly in agreement with this model. Moreover, it is shown that the amount of free charge on the TiO2 NWs is sufficient to observe a similar rotational behavior for these NWs as well, under the same experimental conditions. Therefore, all high-aspect-ratio metallic Ag and non-metallic TiO2 NWs demonstrate an identical rotational speed in the same dielectric liquid and electric field. Finally, we present an approach for collecting, charging and exceedingly fast acceleration of Ag NWs using an external static electric field. It is revealled that despite of an extremely low Reynolds number for the motion of nanowires in viscous liquids ~ 〖10〗^(-5), speeds as high as 50 mm/s are achievable for these nanowires. Comparing the nanowires’ speed with the expected dynamical equation, the net charge on the NW is estimated at about ~1×〖10〗^(-8) C
  9. Keywords:
  10. Silver Nanowire ; Electrical Field ; Dielectrophoresis Technique ; Rotation ; Translational Motion ; Titanium Oxide Nanowire

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