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Abstract

Microfluidics has become an increasingly popular field in the past few decades, with post-COVID era research driving the field toward precision and personalized medicine at the point-of-care. This thesis introduces a system-level design of microfluidic flow control and sensor-level design integration of on-chip flow rate sensing on a silicon-on-insulator (SOI) process. Microfluidic systems are indispensable in diverse research fields, such as biomedical diagnostics, bioengineering, and environmental monitoring, due to their ability to manipulate minute fluid volumes with high precision and efficiency. This capability enables enhanced control over chemical reactions, reduces reagent consumption, and improves the overall sensitivity of diagnostic assays. Traditional commercial flow control systems, however, often rely on bulky and expensive setups, which limit their portability and adaptability. The system-level work introduces a compact and automated microfluidic flow control system designed for the precise delivery and control of multiple reagents at a fraction of the commercial cost. This system features 2 channels with 8 reservoirs per channel that can be simultaneously controlled and automated to deliver a sequence of reagents within a considerably portable form factor, making it well-suited for both laboratory and field-based applications. The performance of the system is validated through characterization, demonstrating stable and consistent reagent delivery across a range of flow rates. Silicon photonic (SiP) biosensors promise portable and analytical systems at the point-of-care. An on-chip in-channel flow sensing solution could improve the robustness and accuracy of SiP biosensor-based measurements and augment datarich readout. The sensor-level work presents the design, integration, characterization, and validation of an on-chip silicon photonic microfluidic thermal flow-rate sensor on an SOI process to non-intrusively measure the flow rate inside a microfluidic channel. The calorimetric sensor architecture consists of a titanium-tungsten microheater placed under the fluidic channel with two silicon photonic microring resonators placed equidistantly upstream and downstream from the microheater. The proposed design is compact, inexpensive, portable to any photonic foundry process, convenient for integration, and comparable in performance to commercial off-chip calorimetric flow rate sensors. This work demonstrates the first successful attempt at integrating a compact, inexpensive SiP microfluidic thermal flow rate sensing solution on an SOI process.