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Design and Simulation of a Spiral Based Microfluidic Device for Separation of Circulating Tumor Cells Using Tunable Nature of Viscoelastic Fluid

Nouri, Mohammad Moein | 2022

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 55269 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Saeedi, Mohammad Saeed
  7. Abstract:
  8. Nowadays, cancer, which has been mentioned as the disease of the century, is the second leading cause of death throughout the world, and its incidence is constantly increasing. Isolation of circulating tumor cells is one of the most critical steps in diagnosing and controlling cancer progression. Due to the rarity of cancer cells compared to other cells in the blood sample, the isolation process requires optimal and high-precision devices. With the advent of inertial microfluidics, the ability to control the particles movement, the processing of blood samples as quickly and accurately as possible, and the viability of cells with a high percentage, introduced microfluidic systems as a suitable platform for processing and separation of blood cells. The basis of particle separation in inertial microfluidics is the interaction of the hydrodynamic forces in the microchannel and the focusing position of the particles. In the present study, the process of particle focusing in straight and spiral microchannels in the elasto-inertia flow regime was investigated using direct numerical simulation method to enlist the tunable properties of viscoelastic fluid. First, the performance of this method was evaluated using a finite element model. According to the results obtained for straight microchannels, there will be five equilibrium positions in the center and each of the corners of the microchannel at lower flow rates. Moreover, there will be one equilibrium point in the center of the microchannel at higher flow rates. The equilibrium position for a 10μm particle in a spiral microchannel with a rectangular cross-section comprised a width of 200 μm and a height of 50μm at 12.5 μL⁄min and 25 μL⁄min was calculated to be 0.25 and 0.65 half of the microchannel width, respectively. After investigating the performance of elasto-inertial regime in the spiral microchannel, we designed a two-stage microfluidic system to reduce the sample processing time and increase the accuracy and the resolution of continuous particle separation at high flow rates. According to the results obtained for the pre-focusing stage, the equilibrium position of 10μm particles at the flow rate of 100 μL⁄min and 1000 μL⁄min would be at a distance of 0.75 and 0.84 half of the microchannel width from the center of the and for a 20μm particle at a distance of 0.79 and 0.85 half of the microchannel width was calculated from the center of the microchannel. By calculating the inertial forces exerted on particles of different sizes, it was shown that for particles with diameters of 15μm and less, the dean drag force overcomes the shear gradient force in the middle region of the stair-like cross-section and pushes the particles towards the outer wall. On the other hand, Particles with diameters greater than 15μm remain at the inner wall of the microchannel
  9. Keywords:
  10. Circulating Tumor Cells (CTC) ; Spiral Microchannel ; Direct Numerical Simulation (DNS) ; Inertial Microfluidic Device ; Particles Separation ; Elasto-Inertial Microfluidics

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