| Disease diagnosis at an early stage requires the availability of inexpensive platforms which can accurately and rapidly analyze a wide panel of biomarkers. Current techniques for biomarker detection include culture enrichment for detection of target cells, ELISA for protein analysis, and DNA microarrays for nucleic acid biomarkers. These expensive and time consuming methods can take several days. Described in this thesis is the design, fabrication, and testing of a rapid and inexpensive electrical biosensor, involving the use of microelectrodes in a micro-channel, which can be used to detect and quantify target cells, protein biomarkers, and nucleic acid biomarkers.;For target cell detection, we have successfully demonstrated real-time detection of target yeast cells by measuring instantaneous changes in ionic impedance. We have also demonstrated the selectivity of our sensors in responding to target cells while remaining irresponsive to non-target cells. We have also applied our biochip to the detection of target protein biomarkers using protein functionalized micro-channels for the rapid electrical detection and quantification of any type of target protein biomarker in a sample. We successfully demonstrate detection of anti-hCG antibody, at a concentration of 1ng/ml and a dynamic range of three orders of magnitude, in less than one hour. Finally, we have demonstrated the ability of our platform to electrically detect the hybridization of DNA molecules within seconds which is four orders of magnitude faster than the conventional DNA microarray technology.;We envision the integration of our biochip and a CMOS integrated circuit into a portable handheld device for multiplex high throughput analysis using an array of micro-channels for probing clinically relevant samples such as the human serum for various protein and nucleic acid biomarkers for cancer detection, and also the detection of pathogenic bacteria in solution. |
