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Regulation of Nanoparticles Translocation Using Nanopore Gating

Karamad, Mohammad Sadegh | 2024

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 57482 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Taghipoor, Mojtaba
  7. Abstract:
  8. In recent years, significant attention has been given to methods for measuring micrometer and nanometer biological and synthetic particles using microfluidic systems. One such method is resistive pulse sensing, which is used to detect and count particles as well as determining their surface charge. This technique is based on Coulter's principle. When a micropore is placed in an electrolyte solution containing the target particles, a drop in electric current occurs as the particles pass through the pore. Electrodes on either side of the micropore allow for the analysis of the pulses generated by the particles. Tunable resistive pulse sensing enables the adjustment of the pore size, allowing for the examination of solutions with varying particle sizes. Adjusting the micropore diameter affects the number of particles that can pass through, which has applications in drug delivery and the preparation of solutions with specific concentrations. In this study, zero-depth micropores were fabricated using soft molding and hot embossing techniques. These micropores were then used to sense polydisperse glass particles and monodisperse polystyrene particles. The accuracy of the estimated diameters of polydisperse particles using resistive pulse sensing was compared with results from scanning electron microscopy. Diameter estimation was performed using a calibrated linear relationship between the ratio of the diameters of monodisperse particles to the pore diameter and the relative amplitude of the pulses. The study also investigated the effect of changing the micropore diameter on the particle rate using a bending mechanism. The number of particles passing through the micropore was determined by counting the pulses in the output signal. Applying pressure to the electrolyte solution compartment also altered the micropore diameter. The effectiveness of bending and pressure mechanisms in changing the micropore size and particles’ rate was compared. Additionally, the study examined how changing the pore size affected characteristics of pulses such as relative amplitude and width. Further research explored the impact of factors like membrane thickness, electrolyte concentration, and the potential difference applied to the electrodes on the number and speed of particles passing through the pore. The speed of particles was compared by measuring the pulse width. It was noted that higher concentration and potential difference accelerated the movement of particles through the pore. However, a thicker membrane slowed down the particle passage rate. Additionally, not using surfactant during particles dilution had a similar effect to increasing membrane thickness, resulting in fewer detected pulses.
  9. Keywords:
  10. Resistive Pulse Sensing ; Particle Size Detection ; Tunable Pore ; Bending Mechanism ; Controlling Particles’ Passing Rate ; Coulter's Principle

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