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Design and Fabrication of a Microfluidic System for Simultaneous Delivery of Two Reagents on a Millimeter-Sized Tissue

Rismanian, Milad | 2021

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 53792 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Saeedi, Mohamad Saeed; Kashaninejad, Navid
  7. Abstract:
  8. It is of great interest to investigate the effects of different concentrations of chemical species on the behavior of test samples. For example, while developing a new drug, pharmacologists are concerned with the behavior of the live sample against different drug concentrations. Microfluidic systems are the new engineering platforms developed for simplifying these experiments. The main goal of the current study is the design and fabrication of a microfluidic system with the capability of generating a continuous concentration gradient from two species simultaneously on a millimeter-sized test sample. Such a system creates many benefits for researchers using microfluidics technology. Our designed microfluidic system is comprised of two parts. The first part is a concentration gradient generator manufactured by micromachining and the second part is the main chamber manufactured by laser cutting. The fluid flows through the microfluidic section using a syringe pump. The finite volume numerical simulation is performed to estimate the concentration gradient generated through the sample.Moreover, to estimate the diffusion coefficient of chemical species, the forward-reverse steered molecular dynamics with constant velocity has been applied. Na ion diffusivity is calculated using this method, and the comparison of the result with experimental reports shows acceptable agreement. Then temozolomide diffusivity in water is calculated using this molecular dynamics approach, and the result is used as an input parameter for finite volume numerical simulation of temozolomide distribution in the microfluidic system. The concentration distribution of two food dyes in water was computed and compared with experimental results to validate our numerical simulation. For this purpose, the concentration distribution in millimeter-sized brain tissue of a three-month-old mouse with 300-micron thickness is experimentally tested. A cheap and straightforward optical approach is used for simultaneous concentration measurement of two dyes. The comparison of numerical and experimental results shows the maximum root mean square errors of 4.53 and 8.19 % for the first and second dyes. Our results show that the first dye has a linear concentration gradient across the sample width and the second dye has a near-linear concentration gradient along the sample length. These concentration gradients provide complete combinations of the two species to test their effect on the test sample. Moreover, in the current study, an optimum approach for designing microfluidic concentration gradient generators is presented by defining non-dimensional mixing length
  9. Keywords:
  10. Microfluidic System ; Concentration Gradient Generator ; Two Species Simultaneous Test ; Tree-Like Concentration Gradient Generator ; Concentration Measurement Optical System ; Molecular Dynamics

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