Buffer transfer of cells is a critical process in many biomedical applications such as dielectrophoresis experiments, optical trapping, and flow cytometry. Existing methods for buffer transfer of cells are time consuming, require skilled technicians and involve expensive equipment such as centrifuge and bio safety hoods. Furthermore, even a minute error in transferring the cells can easily result in cell lysis and decrease in viability. In this work, a lab-on-a-chip device is proposed that uses a textit{passive microfluidic approach} to effectively transfer cells from a growth medium to a desired buffer for downstream cDEP analysis. This eliminates the need for any external fields, expensive equipment, and significantly reduces manual efforts. Computational studies were carried out to analyze the impact of device geometry, channel configuration, and flowrate on the effectiveness of buffer transfer. The proposed device was evaluated through a parametric sweep and the device configurations were identified that induce low values of fluid shear stress, support high throughput, and maintains minimal diffusion. Finally, a method for fabricating the device in the laboratory using PDMS was illustrated. The outcome of this study helps further the development of highly effective microfluidic devices capable of performing buffer transfer of multiple cell lines. / Master of Science / Prior to performing biomedical experiments, cells often need to be transferred from the chemical solution in which they are grown to a different buffer that is customized for the analysis technique. This process is called buffer transfer and it is a critical process that needs to be performed before running many cell experiments. The way in which buffer transfer is carried out in most labs is time consuming, requiring skilled technicians and expensive machines. Moreover, even a small error while performing buffer transfer can easily cause the cells to die and reduce the cell count available for performing experiments. In this work, we propose an easy-to-use device that can perform the buffer exchange process without the need for expensive technologies or skilled technicians. The device achieves this exchange by leveraging fluid flow the channel to filter the cells out of the growth medium and transferring the cells to the desired chemical solution while washing the unwanted chemical solution away. We used CAD modeling and computational analysis to develop the device. The performance of the device was enhanced through a parametric analysis such that the device induces low shear stress, supports high flow through the channels and limits the mixing between the growth medium and the buffer. Finally, we have also illustrated a method for building the device in the laboratory. The results of this research work would help in furthering current efforts in the buffer transfer of cells.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/106644 |
| Date | 12 November 2021 |
| Creators | Thattai Sadagopan, Sudharsan |
| Contributors | Engineering Science and Mechanics, Stremler, Mark A., Boreyko, Jonathan B., Davalos, Rafael V. |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | ETD, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
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