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Microfluidic structures for separation of blood cells and bacteria

Gao, Yang (2009) Microfluidic structures for separation of blood cells and bacteria.

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Abstract:The principal method for the diagnosis of infectious diseases involves the culturing of pathogens isolated from the patient. Currently, such macroscopic handling of patient samples can take up several days,which is inadequate when life-threatening infections promptly need to identified. Also, a significantportion of sample handling is still performed manually. Reducing (1) the analysis time, (2) cost and (3)handling errors and (4) increasing the availability of point-of-care treatment can be realized byintegrating complex lab-on-a-chip devices into an in vitro diagnostics device. In this work, several lab-on-a-chip devices were designed, simulated, fabricated and tested that enable a clinically relevant sample preparation step, i.e. the separation of bacteria from a human whole blood sample. Here, passive microfluidic structures were proposed that use continuous flow separation method for the subsequent size based separation between human cells and bacteria. Since the separation process is predominantly depending on structure geometry, minimal flow tuning is required after microfabrication. The proposed structures were simulated with Comsol Multiphysics before realized, using softlithography technology and PDMS. The realized structures were subjected to a variety of experiments that qualitatively and quantitatively characterize their separation performances. Fluorescence and highspeed camera measurements qualitatively showed the successful separation of suspended beads/cells to distinctive outlets. Here, simulated trajectories of beads indeed correspond to the visualized beadtracks obtained with the high-speed camera. Furthermore, an 10x diluted mixture of normal human whole blood with B. Subtilis was introduced and successfully separated by directing the WBCs and the bacteria to distinctive outlets. Lastly, end-point efficiency measurements were conducted with a suspended beads solution and ~100% and ~60% of the introduced 10 and 2 μm beads were successfully collected at the intended outlets. Theoretical models that were used to design the devices are hereby verified and lead to the development of a microfluidic protocol for the realization of a generic passive sample preparation module which can be tailored with design rules for specific application and has the potential to be a true enabler for automated point of care devices.
Item Type:Essay (Master)
Philips Research
Faculty:EEMCS: Electrical Engineering, Mathematics and Computer Science
Subject:53 electrotechnology
Programme:Electrical Engineering MSc (60353)
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