LEE- Makina Mühendisliği Lisansüstü Programı

Bu topluluk için Kalıcı Uri

http://hdl.handle.net/11527/19371

Gözat

Konu "Mikromekanik" ile LEE- Makina Mühendisliği Lisansüstü Programı'a göz atma
  • Öge
    Development of microfluidic systems for differential sorting of microparticles and investigation of their performances
    ( 2020) Erdem, Kaan ; Kuddusi, Lütfullah ; Koşar, Ali ; 636269 ; Makine Mühendisliği Ana Bilim Dalı
    Inertial microfluidics, an emerging tool in scientific studies, offers rapid, continuous, and high-throughput cell/particle separation. They can be mainly utilized in various applications such as blood separation, the isolation of cancer cells (Circulating Tumor Cells), disease diagnostics and monitoring, and biological processes. For the isolation of targeted particles or cells at the micro scale, a variety of methods has been proposed. Among these methods, label-free, size-dependent cell-sorting applications based on inertial focusing phenomena have attracted much interest during the last decade. In this thesis, five-loop spiral microchannels with a height of 90 µm and a width of 500 µm are introduced. Unlike their original spiral counterparts, four of the proposed channels have elliptic configurations of differing elliptic aspect ratios of 3:2, 11:9, 9:11, and 2:3. Accordingly, the curvature of these configurations increases in a curvilinear manner through the channel. Additionally, the other of proposed microchannel differs due to the implementation of a filtration platform consisting of cylindrical microposts. Both microchannels were designed in order to improve the separation capability. The proposed microchannels were fabricated by using the standard soft lithography method. As channel material, PDMS (polydimethylsiloxane) was utilized. The steps of the microfabrication process were adjusted in order to meet the predetermined geometical features. The fabrication of the cylindrical microposts was challenging due to several reasons such as low quality of printed photomasks, loss of some microposts during PDMS cast (channel material) removal and clogging problem by dust and debris in the experiments. Therefore, the study was carried out with the elliptic configurations. The effects of the alternating curvature and the channel Reynolds number on focusing of fluorescently dyed particles with diameter of 10 and 20 µm in the prepared suspensions were investigated by using the fabricated microchannels. After focusing particles at distinctive positions across the microchannel, the optimum volumetric flow rates between 0.5 mL/min and 3.5 mL/min allowing separation were determined for each channel. These flow rates were specified by utilizing the captured microscopic image sequences of the particle migration trajectories at the outlet. At these rates, each channel was tested in order to collect samples at the designated outlets. Then, these samples were analyzed by counting particles visually under a fluorescence microsope to determine the separation purity. As a result, these elliptic microchannels were capable of separating 20 and 10 µm particles with total yields up to approximately 95% and 90%, respectively. The results exhibited that the level of enrichment and the focusing behavior of the proposed configurations are promising compared to the existing microfluidic channel configurations. Considering their advantages as high operating flow rates, non-complex configuration, and less expensive process requirements, these microfluidic devices offer cost-effective and high-throughput prototypes for efficient separation of microparticles/cells such as CTCs, blood cells, bacteria, viruses, etc. and could be further customized for various sorting applications.