Laminar flow-based microchemical systems for power generation, electrochemical synthesis, and biological cell studies

With the ability to create fluidic networks at the sub-millimeter level, research in miniaturized chemical systems for chemical and biological applications has gained significant momentum over the last decade. While different transport and physiochemical phenomena in microfluidic systems offer exciting new possibilities, the understanding of these phenomena at the microscale is of the utmost importance for the development of specific microfluidic devices. This thesis describes the development of microchemical systems that utilize the physical characteristics of the microscale, specifically a novel membraneless microfuel cell, a biocatalytic microreactor, and a platform for biological cell studies.; The main focus of this thesis is the development and analysis of a fuel cell that utilizes multistream laminar flow at the microscale to eliminate the need for a physical membrane to separate the anode and cathode. This membraneless laminar flow-based design solves many of the problems associated with the commonly used proton exchange membrane design such as fuel crossover, membrane dry out, cathode flooding, and media limitations. The concept of this novel fuel cell is demonstrated with different fuels, oxidants, and catalysts. Further analysis is conducted with an external reference electrode, enabling the separation of cathode and anode behavior and a more precise identification of performance limiting factors. In addition, a detailed study of performance in different media---acidic, alkaline, and combination there of---is conducted.; Similarly in this thesis, multistream laminar flow is used in microfluidic systems for (1) biocatalytic synthesis of fine chemicals by microscale-enabled efficient regeneration of cofactors, as well as for (2) the study of intestinal stem cells on a surface that mimics their in vivo environment. In the first system, the ability to focus reagent streams close to the electrode wall results in a cofactor regeneration efficiency of over 30%. In the second system, microfluidic networks are used to create covalently immobilized surface gradients of extracellular matrix (ECM) proteins, laminin and collagen 1. These microfluidic platforms are capable of eliciting cell responses such as migration, proliferation, and differentiation, and offer the possibility of in vitro studies of a variety cell lines in response to different immobilized and soluble ECM components.