Novel Capacitive Sensor for Detection of Concentration of Solids and Bacteria in Water

Quantifying the detection of suspended and dissolved solids and microbiological pollutants in water samples with the use of a novel capacitive sensor provided insight into the overall utility of electromagnetic sensing in an aqueous environment. Sludge, sugar, salt, and Escherichia coli (E. coli) dilutions were analyzed at different concentrations in this aqueous environment. To measure the concentration of these compounds, dilution series of each of them was prepared. A small sample of these dilutions (2 mL) was pipetted to the “active sensing area” of the sensor where values of concentration were displayed by an accompanying software display as sensor output counts. These compounds were also measured through standard methods: The determination of moisture content and total solids was determined by measuring the mass of a sludge before and after the water is removed by evaporation in an oven. Concentrations of E. coli were determined by the standard EPA method 1603 consisting of membrane filtration followed by incubation. Concentration of salt and sugar was determined by preparing a solution of known concentration, preparing dilutions series and determining concentration of them by calculation. The results obtained by the novel method were then plotted against the results obtained by the standard methods, generating the calibration curve. Preliminary results indicate that the novel sensor is effective at detecting both suspended and dissolved solids at very low concentrations. Further results indicate that E. coli is consistently quantifiable at a range of 1.00 x 104 to 1.00 x 108 CFU/mL. This sensor has a wide range of potential applications spanning both the water treatment and homecare industries. It’s more efficient, accurate, and costs significantly less than other sensors of its kind (microfluidic and fluorescent sensors)