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Design and Study of a Resistive Pulse Sensing System with a Tunable Pore

Shoghi Tekmedash, Mohammad | 2022

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 56048 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Taghipoor, Mojtaba; Shafii, Mohammad Behshad
  7. Abstract:
  8. Over the last few years, exploiting particle sensing systems for micro-nanoparticles has grabbed much attention. Attaining the physical properties of particles using resistive pulse sensing has been one of the utmost applicable methods of sensing particles. Pores are pivotal elements of systems based on resistive pulse sensing. Two electrodes are placed at both sides of the pore, filling the containers with an electrolyte solution. Pulses of particle translocation across the pore can be recorded by applying a voltage across the electrodes. In more developed versions of resistive pulse sensing systems, pore size is tunable to attain polydisperse particles within a dispersion. In subsequent research, mechanisms of pore tuning could only expand the pore size. In the present work, besides proposing bending as a novel pore-resizing mechanism, the pore diameter can also shrink. Electrochemical impedance spectroscopy is utilized to study pore resizability under multiple bending angles in the suggested mechanism. Also, a bending effectiveness criteria is introduced for measuring pore resistance at the beginning, middle, and end of the bending range, proving an increase in the bending effectiveness as the neutral pore diameter declines. As the neutral pore diameter decreased, in the 0.4-micron pore, an eight-fold decrease in the pore size was observed, achieving a 50nm pore. Furthermore, using mono-dispersed polystyrene analytes in the pore under bending, as expected, an increase in the pulse amplitude was recorded as the pore size shrank. Elevation in the pulse amplitude improves the ratio of the detected signal to noise. Also, using pulse amplitude of 1.1 and 2-micron polystyrene particles, a third-degree polynomial calibration relation was derived relating the pulse amplitude to the ratio of the particle diameter to pore diameter. For dispersion with unknown particle sizes, by knowing the pore diameter and the pulse amplitude, the latter relation assists in attaining the particle diameter range with a prediction interval of 95 percent. The outlook of the introduced method indicates a molecular sensing system with a nanopore having a straightforward fabrication technique and resizing mechanism. In addition, as the pore diameter shrank, an exponential curve with a confidence interval of 97 percent marked a decrease in the rate of particles crossing the pore. This significant reduction can be considered a novel and effective particle gating mechanism
  9. Keywords:
  10. Resistive Pulse Sensing ; Bending Effect ; Particle Gating ; Particle Size Detection ; Pore Electrical Resistance ; Tunable Pore

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