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Measuring Dielectrophoresis Force Excerted on Polystyrene Micro-Beads using Optical Tweezers

Mollaei, Parisa | 2016

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 48497 (04)
  4. University: Sharif University of Technology
  5. Department: Physics
  6. Advisor(s): Seyyed Reihani, Nader
  7. Abstract:
  8. The base of dielectrophoresis(DEP) technique has been demonstrated through electro-dynamic interactions between an applied non-uniform AC electric field and induced distributed dipoles within a polarized. In particle manipulation and/or separation using the DEP method, knowledge of precise DEP force of a particle is essential in designing a DEP device and improving its separation efficiency and accuracy. In most DEP studies related to particle manipulation and/or separation, however their absolute DEP forces remain unknown[2]. Insufficient information regarding the DEP behavior of particles can result in preventing a strategic maneuver for efficient particle manipulation and/or separation based on DEP.In this report, a convenient method to precisely monitor DEP behaviors of polystyrene has been described. Optical tweezers combined with a simple microelectrode device are suggested as measuring equipment. Optical tweezers consist of a tightly focused laser beam. Particle with refractive index greater than that of the surrounding medium are eligible for optical trapping. This device is used for measuring forces from pico-newton to nano-newton, and displacement from nanometer to micrometer. Measure of DEP forces is also in order of pico-newton, so the Optical Tweezers is a suitable device to measure the DEP forces.The method consists of a two step process; first, a micro-electrode device is used to generate the DEP force acting on polystyrene micro-beads, and then, the optical tweezers directly measure the DEP force through trapping target polystyrene
  9. Keywords:
  10. Optical Tweezer ; Polystyrene ; Fines ; Dielectrophoresis Technique ; Induced Dipole

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