Study of passive fluid mixing in microfluidic devices

Objectives: The main aim of this thesis is to carry out fluid manipulation methods in passive microfluidic devices using experimental design by carrying out experimental investigations of mixing performance of selected passive micromixer design (flow split and merge channel and zig-zag channel) and to compare the effectiveness of mixing across the channels designed and comparing them with the straight channel. Materials and Methods: In this study, the fluidic devices were first designed using computer aided design software SolidWorks. The CAD process begins with the conceptualization of the device's functionality and performance requirements. CAD software, tailored specifically for microfluidics, was used to create a digital representation of the device. The zigzag and flow-split fluidic channels designs were implemented for passive fluid mixing experiments. After the design process, the devices were 3D printed using an Ender 3 S1 commercial grade 3D-printer. Mixing experiments were performed using a lab-built syringe pump. Results: The results showed that the zigzag device required higher total flow rates to achieve uniform mixing compared to the flow-splitting device. Flow profiles were characterized across the channel width, and it was found that higher flow rates were necessary for the zigzag device to obtain evenly distributed flow profiles. Conclusion: This research contributes to the advancement of microfluidic technology by demonstrating the design and fabrication of 3D-printed devices for passive fluid mixing. The findings provide valuable insights into the flow behavior and mixing efficiency of different device geometries, laying the foundation for future developments in this field