Development of potable water systems throughout the less developed world necessitates a rapid and accurate method of water quality analysis. Poor water quality is commonly determined by the presence of E. coli. This bacterium leads to multiple health problems and in the cases of the elderly or very young ingestion of E. coli may lead to death. Currently a device known as a biosensor is under development. This device utilizes change in the natural frequency to detect small masses such as E. coli and requires much less time in comparison to current methodology. Although there are multiple types of biosensors, the most sensitive to small changes in mass is the dynamic piezo-electric millimeter size cantilever, or PEMC. This project investigates the mass sensitivity and construction of a dynamic PEMC. Due to the difficulties associated with construction, prototype cantilevers are scaled to the centimeter scale. To reduce the number of prototypes constructed, computer models are developed and validated to within 12% of published values. This model is then utilized to predict response of prototype cantilevers. To analyze sensitivity to mass change a series of experiments are performed measuring the change in frequency with the addition of 10 µg, 20 µg, and 30 µg respectively. The prototype cantilevers performed as expected showing significant shifts in frequency due to mass with the best equipment resolution being in the range of 2 to 3 kHz with a mass sensitivity of 130 Hz/1 µg.
