Biosensors are used in diverse applications spanning from clinical diagnosis and drug discovery to environmental and safety monitoring. Among different types of biosensors, electrochemical ones have demonstrated high sensitivity, short detection time, and selectivity with a low cost, and have been widely used to detect various diseases. In this thesis, we have introduced an inexpensive, rapid, sensitive, and quantifiable impedance-based immunosensors to evaluate SARS-CoV-2 neutralizing antibody (NAb), which shows the real protective immunity against COVID-19. We demonstrated that our device enabled assessment of NAb in a physiological buffer with conductivity equivalent to that of blood plasma. This technique can be used to evaluate NAb in people's blood serum from 50 ng/ml to 190 ng/ml before receiving further COVID vaccine doses. We further analyzed Joule heating induced transport phenomena as a potential method to increase detection in electrochemical biosensors. Buoyancy-driven and AC electrothermal (ACET) flows are the main transport mechanisms that induce two competing flows. Using a scaling analysis, we introduced a new non-dimensional parameter, which enabled the construction of a phase-diagram that can predict the dominance of ACET and buoyancy driven flows as functions of the channel size and electric field.
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Dehghan Manshadi, Mohammad Karim, "Transport Mechanisms in Electrochemical Immunoassay Biosensors with Applications to SARSCOV-2 Neutralizing Antibody Detection" (2023). Mechanical Engineering Research Theses and Dissertations. 55.