Detection and quantification of pathogens, proteins, and molecules using piezoelectric-excited millimeter-sized cantilever (PEMC) sensors

In this study novel rectangular-shaped piezoelectric-excited millimeter-sized cantilever (PEMC) sensors were fabricated and shown to have picogram to femtogram sensitivity under liquid flow conditions (0.05 to 0.74 cm/s). Sensitivity is characterized by detecting pathogens, proteins, and small molecules: Escherichia Coli O157:H7, Bacillus anthracis spores, and Group A Streptococcus at 1, 300, and 700 per mL, respectively. Staphylococcal enterotoxin B, a food toxin, was detected at 50 pg/mL, and the adsorption of 1-hexadecanethiol at 1 nM was measured. The sensors were operated under both batch and flow configurations in various sensor flow cell (SFC) geometries. Flow was shown to double the detection sensitivity for the same sensor design. Robustness of PEMC sensors was demonstrated under various flow rates, ranging of 1 to 17 mL/min. The sensors showed frequency fluctuations of ± 20 Hz over the flow rate range investigated, which is on the noise level of the device. The recognition layer (antibody) was shown to be regenerated at least twice with HCl/PBS buffer (pH 2.0), using model protein BSA, without significant loss in the antibody activity. Selectivity was established by detecting a fix concentration of bacillus anthracis spores (333/mL) in the presence of varying amounts of other bacillus species. A constant total change in resonant frequency was observed in all the experiments with a decrease in binding rate with an increase in the non-antigenic species concentration.Ph.D., Chemical Engineering -- Drexel University, 200