Date of Award


Document Type

Open Access Thesis

Degree Name

Master of Science (MS)


Physics, Applied

First Advisor

Stephen Arnason

Second Advisor

Robert Chen

Third Advisor

Bala Sundaram


Timely and inexpensive monitoring of microbial ecology in the world's water supplies is crucial to the study of environmental and human impact on water quality and the prevention of disease outbreaks. Current technology is lacking in its ability to accurately measure and predict the presence of possible disease pathogens in a timely and cost effective manner. This paper describes the construction and initial testing of an automated prototype water sensor intended to detect fluctuations in microbial density in real-time by using bulk fluorescence of SYBR Gold stained bacteria. The sensor is comprised of off-the-shelf hardware and an in-house designed and built flow-through fluorometer. A flow-through design allows water to be channeled through filters, injected with a fluorescent dye, and then held in the fluorometer while its bulk fluorescence is measured. Preliminary testing has confirmed the prototypes' ability to reproduce a series of dilutions of fluorescein consistent to within 0.8% of a similar manual series; consistently measure the bulk fluorescence of SYBR Gold for specific Lambda DNA concentrations; differentiate between Lambda DNA dilutions as close as 0.05 μg DNA mL-1Milli-Q water; and repeatedly create and measure a dilution of SYBR Gold in Instant Ocean which varied 3.4% from its average. Additional testing is needed to study filter performance and longevity, the prototypes' performance using SYBR Gold with sea water, and the correlation between bulk fluorescence and current water quality testing methods. Items not currently considered include SYBR Gold containment and waste, the use of DNase to improve fluorescence, and gross filtration for larger particles and debris.