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Design and Fabrication of a Microfluidic Chip for Multiplexed Detection of Viruses using Molecular Amplification

Najjar, Maryam | 2024

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 57264 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Tagipoor, Mojtaba
  7. Abstract:
  8. The point of care systems are one of the technological advancements in the healthcare sector, playing a crucial role in improving health care by providing timely and cost-effective information in the care process. Among the important areas of clinical diagnostic systems are microfluidic platforms that analyze fluid behavior through microchannels with minimal sample volume. These systems are particularly important in situations such as widespread diseases and rapid diagnostics. The ability to detect multiple targets in a single sample becomes crucial, especially when collecting clinical samples is challenging, or their volume is limited, or when various disease-causing agents can produce similar clinical manifestations. In this research, a chip for simultaneous detection of multiple genes using a polymerase chain reaction (PCR) method has been designed and fabricated. PCR is considered one of the most reliable early detection methods. The study focuses on the development of a rapid, cost-effective, and accessible microfluidic chip. After choosing the hot embossing method, silicon and polydimethylsiloxane (PDMS) molds have been investigated for this process. Temperature, time, and pressure in the hot embossing process, with the PDMS mold, have a more significant impact. Two designs with different depths and lengths were also studied. With increasing length and depth, the thickness of the channels increased after the hot embossing process. Subsequently, a fluid separation chip was designed and fabricated using gating valves. The sudden expansion created in the path stops the fluid flow. By pressurizing the main fluid flow path and separation channels, the fluid completely separated in the channels, yielding the expected and satisfactory results. Additionally, geometric parameters, flow rate, and input fluid volume were studied for this chip, resulting in a correct fluid separation with a 2:1 ratio of main channel width to separation, and the diameter of the created holes relative to the separation channel, as well as the ratio of input fluid volume to the required separation volume. Furthermore, a mixer design was made to mix the sample with the master mix in the PCR process, providing a solid-liquid combination in the microfluidic platform. For this purpose, an active mechanism was used, applying positive and negative pressure. With this idea, active mixing was achieved without adding new equipment. Increasing the number of fluid back-and-forth cycles also increased the concentration. With less main material, the number of back-and-forth cycles for complete mixing decreased. Also, with the provided fit, the unknown concentration after each experiment was identified. Due to the lack of the original sample, these experiments were conducted with water, as the original sample bears a significant resemblance to water, making the results reliable for this sample as well. Finally, by integrating the separation and mixer sections, a unified chip was manufactured
  9. Keywords:
  10. Point-Of-Care Detection ; Microfluidic System ; Polymerase Chain Reaction (PCR) ; Microfluidic Chip ; Hot-Embossing ; Solid-Liquid Micromixer

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