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Investigation the Interaction of the Colloidal Particles with Magnetic Cores by Optical Tweezers

Kabi, Sareh | 2024

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 57683 (04)
  4. University: Sharif University of Technology
  5. Department: Materials Science and Engineering
  6. Advisor(s): Seyed Reihani, Seyed Nader; Langari, Abdollah
  7. Abstract:
  8. Optimizing optical tweezers and achieving powerful traps has always been a challenging topic for researchers , since the trap stiffness increases with increasing laser power which may damage specimens , especially biological ones and cells . In this thesis , we introduce a special geometry and structure of particles that , have the possibility to increase the stiffness (strength) of the optical trap and cause the magnetic response of particles at optical frequencies . Special geometries such as a combination of dielectric particles with magnetic nanoparticles that emphasize the role of the laser magnetic field and lead to changes in the electrical and magnetic properties at the laser focal point . In the first step , the micron-sized polystyrene (PS) particles including the super-paramagnetic nanoparticles were prepared . In the following steps , the results of optical trapping show that the wise choice of the diameter of the produced particles can lead to the more stiffer trap , which can be interesting when measuring larger and more accurate forces is on demand . The magnetic moment , the magnetic permeability and... can also be measured using optical tweezers . Therefore , the implementation of composite particles not only increases the stiffness of the trap , but also produces magnetic moments in the micrometer and nanometric structure with a magnetic permeability higher than one (µ> 1) . Finally , all experimental results are confirmed by our simulation data , which shows reasonable watching
  9. Keywords:
  10. Optical Tweezer ; Optimization ; Superparamagnetism ; Optical Trapping ; Optical Trap Stiffness ; Magnetic Permeability

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