Term of Award

Spring 2023

Degree Name

Master of Science, Applied Physical Science

Document Type and Release Option

Thesis (open access)

Copyright Statement / License for Reuse

Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.


Department of Physics and Astronomy

Committee Chair

Dragos Amarie

Committee Member 1

Dr. Hau-Jian Liu

Committee Member 2

Monique Aller


Investigation of cell chemotaxis requires controlled chemical gradients. We investigated microfluidic devices that could enhance small populations' cell assays because of their ability to generate various chemical gradients. Our five designs generate different chemical concentration landscapes that we can easily convert into tools to study cell response to growth factors. Gradient landscapes occurred by splitting and mixing two input fluid concentrations using bifurcations, trifurcations, and Y-mixing junctions in three consecutive steps. Such fluid flow manipulations resulted in nine concentration streams entering a 0.54-mm-wide gradient chamber. The first design used a 1:1 ratio Y-mixer (unbiased) when blending two concentrations, resulting in a mostly linear gradient across a chamber. The other four designs incrementally increased the bias of the Y-mixer up to a 5:1 ratio to achieve gradient non-linearity across a chamber. We developed a protocol for the fabrication of these microfluidic chips. Following the fabrication process, epi-fluorescence microscopy was used to visualize the resulting gradient landscapes in the chamber. Analysis of the fluorescence intensity across and along the chamber revealed gradient concentration profiles comparable to simulated profiles created in COMSOL Multiphysics software. Our study showed that the 3:1 bias design unexpectedly generated the most extensive range of concentration along the length of the chamber.

Research Data and Supplementary Material