The portable TLF fluorimeter uses the concepts of fluorimetry to analyze water samples for biological contamination. The design uses low-cost, high-intensity light sources to shine 280 nm wavelength light on a water sample. Since the cell walls of pathogenic bacteria such as <i>E. coli</i> contain proteins which emit light at 350 nm when excited by 280 nm, pathogenic bacteria can be identified in real time with light. This excitation-emission profile is the Tryptophan-like-Fluorescence (TLF) range. Optics are used to concentrate emitted light from the water sample into a 350 nm light filter. This filter lets only the light created during fluorescence to reach a photodiode, which increases voltage as more 350 nm light hits it. The signal from the photodiode is amplified and then tracked by a microprocessor. Data from this can give either a positive/negative reading, or an approximate contamination level based on previous data, depending on the desired setting. The system is contained in a box that an individual can carry, making it easily portable to testing locations. The detection limit for the current prototype iteration is 80 CFU/mL, though some tests have reached the 8 CFU/mL level. Additional improvements to optics and signal processing will push the limit of detection down to the desired 1 CFU/mL level for future deployment and for field deployment. A labeled diagram of the system is attached below in Figure 1.

TLF sensor prototypes: Low-cost sensors for detecting biological contaminants in water

2019 Fall National Meeting

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