An integrated microelectronic device for biomolecular amplification and detection

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2007.Includes bibliographical references (p. 133-154).The extraordinarily high sensitivity, large dynamic range and reproducibility of polymerase chain reaction (PCR) have made it one of the most widely used techniques for analyzing nucleic acids. As a result, considerable effort has been directed towards developing miniaturized systems for PCR, but most rely on off-chip optical detection modules that are difficult to miniaturize into a compact analytical system and fluorescent product markers that can require extensive effort to optimize. This thesis presents a robust and simple method for direct label-free PCR product quantification using a microelectronic sensor. The thesis covers the design, fabrication, and characterization of the sensing technique and its integration with PCR microfluidics into a monolithic detection platform. The sensor used in this thesis study is an electrolyte-insulator-silicon (EIS) device fabricated on planar silicon substrates. Based on electronic detection of layer-by-layer assembly of polyelectrolytes, the sensing technique can specifically quantify double-stranded DNA product in unprocessed samples and monitor the product concentration at various stages of PCR to generate readout analogous to that of a real-time fluorescent measurement.(cont.) Amplification is achieved with integrated metal resistive heaters, temperature sensors, and microfluidic valves. Direct electronic quantification of the product on-chip yields analog surface potential signals that can be converted to a digital true/false readout. A silicon field-effect sensor for direct detection of heparin by its intrinsic negative charge has also been developed. Detection of heparin and heparin-based drugs in buffer and serum has been studied, and a study demonstrating strong correlation between electronic heparin sensing measurements and those from a colorimetric assay for heparin-mediated anti-Xa activity has been performed.by Chih-Sheng Johnson Hou.Ph.D