Date of Award
Master of Science in Mechanical Engineering and Applied Mechanics
Mechanical, Industrial and Systems Engineering
The Hook Effect is a phenomenon that occurs within microfluidic tests, whereby a reduced signal response is observed as a result of an over-abundance of analyte. This study demonstrates the development of a microfluidic chip device that significantly reduces the impact of the Hook Effect in sandwich assays. This is achieved through the conception, characterization, and implementation of a novel microfluidic valve, The mono-material cantilever valve. This valve uses the capillary behavior of fluid traveling through paper to straighten out a bent beam of paper. The straightened piece of paper contacts a channel on the other end, meaning the fluid on the other side is held in place until the valve is actuated. The new microfluidic chip, dubbed the SuperLoop, uses two cantilever valves to sequentially apply a wash step, followed by the gold-nanoparticle connected antibodies automatically after the user adds sample fluid. This process washes away the excess analyte, reducing the presence of the hook effect in fluidic tests being run at high concentrations. For the purpose of developing and testing this device, commercially available pregnancy tests were tested at high hCG concentrations to isolate the Hook Effect within them. The hook effect was determined to occur with sample fluid hCG concentrations ranging from 1.092*106IU/L to 1.092*109IU/L. The active components were then removed from these tests and placed within the SuperLoop device, and this new device was tested at the same concentrations. The results of both tests were then compared, and the SuperLoop's performance was analyzed. The SuperLoop showed a 38.5\% reduction in Hook Effect spread.
Lemos, Nicholas, "Elimination of the Hook Effect Using Microfluidic Valves" (2018). Open Access Master's Theses. Paper 1409.