Development of 3D-printed droplet-based microfluidic devices for biosensing applications

This thesis explores the area of droplet-based microfluidics, investigating the underlying principles, fabrication technique, and experimental methodologies of this rapidly evolving field having the aim of developing devices capable of encapsulating biological molecules (e.g., dopamine) in a droplet for later measurement of the encapsulated molecule concentration by a biosensor embedded under the microfluidic chip. The first chapter introduces the field, explaining the background and the motivations driving research in droplet-based microfluidics. The chapter also describes the thesis's structure. The second chapter, the literature review, delves deeply into the fundamental concepts required to comprehend droplet-based microfluidics. It presents the fundamentals of microfluidics, including laminar flow, fluid dynamics, and the critical dimensionless parameters that govern fluid behaviour at the microscale. The chapter additionally discusses droplet generation mechanisms, including passive and active methods, and various applications of droplet-based microfluidics. The fabrication methods and experimental techniques are described in detail in Chapter 3. This section discusses the materials and methods used in device fabrication, with an emphasis on stereolithography (3D printing) and post-processing steps. The experimental setup for droplet generation and size measurement is described, as well as the results of various experiments. Droplet generation factors such as microchannel geometry, carrier oils, and surface tension are thoroughly investigated. The research is expanded in Chapter 4 to include a numerical investigation and computational fluid dynamics (CFD) analysis. This computational method improves our understanding of the complex fluid dynamics involved in droplet formation and manipulation.