Study and Applications of Microfluidic Chips and Miniaturized Systems for Nucleic Acids Analysis

Abstract

Microfluidic chips play an important role in bio/chemical analysis due to their high surface-to-volume ratios, fast heat transfer rates, and ability to manipulate liquids precisely.In this thesis, we studied microfluidic chips and related microsystems based on microchips to apply microfluidic technology to the field of molecular detection. To begin with, we introduced the basic concept of microfluidics, its advantages, the materials currently used in microfluidic chips, and their fabrication and bonding methods. We described microfluidic-based nucleic acid analysis systems in detail, including nucleic acid extraction, microchip-based Polymerase Chain Reaction (PCR), and digital PCR (dPCR), which is an essential application for microfluidics. Then, we developed an automated miniaturized magnetic nucleic acid extraction and purification device, which can rapidly process multiple nucleic acid samples and automate loading and sealing microfluidic PCR chips. After that, we designed a fully portable and fast microchip-based multi-channel real-time PCR system for nucleic acid detection, with a simple sample loading and sealing method. We chose silicon as the microreactor and the microheater substrate due to its good thermal conductivity and the mature fabrication process. In the same PCR program, our portable real-time PCR reduced the detection time by half compared to the commercial PCR instrument and has the same detection limit. Finally, we designed two silicon-based power-free dPCR chips using simple and fast sample loading methods without additional precision instrumentation. We also proposed a rapid dPCR platform with pressurized thermal cycling to prevent water evaporation.

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