Polysensor is built to provide a low-cost and easy method for testing impurities in water, with low-cost, rugged and tropicalized sensors. Currently, the instrument can be used to measure pH, Electrical conductance (EC), Total Dissolved Solids (TDS), Nitrate ion, Chloride ion, Salinity. The project is being developed with more parameters to be added such as Fluoride ion, Potassium ion, Ammonium ion, Urea, and Mercuric ion.
The instrument uses two techniques, Conductometry and Potentiometry. The conductometric sensor detects changes in conductance between two electrodes according to the Ohms Law. A conducting polymer ‘polyaniline’ is deposited between two electrodes. The conductance of polyaniline is sensitive to the pH in its normal form. Thus, it can detect any chemical reaction involving change (increase or decrease) of pH.
The potentiometric sensor detects the change in the potential of the electrodes according to the Nernst Law. Nernst equation correlates the concentration of the analyte with the equilibrium potential (which is very specific for a particular concentration, without interference of the other species present).
Water Quality Sensor
Project Firmware, Schematic and Documentation