A strip-based total dissolved solids sensor for water quality analysis

In this study, a portable Total Dissolved Solids (TDS) and Electrical Conductivity (EC) of water sensor using a disposable polymer strip and the readout circuit segments is presented. The strip consists of gold electrodes and a vent hole for water flow injection inside the measurement chamber. This strip reduces the cost of the measurement, decreases the measurement duration, and increases the repeatability of the system. Besides, there is no demand for electrodes cleaning and recalibration of the system. According to the electrical model of strip electrodes and their frequency responses, the EC value is in the range of 78.1–1230.8 (µs)/cm. The experimental tests are carried out based on the frequency method in the concentration range within 50–800 ppm. The results confirm the linear relation of TDS concentration on the EC voltage value which is 1.9 mV for 1 ppm resolution. Also, the effect of temperature variations on the EC value is investigated. Furthermore, the average amount of error for EC measurement exhibits an acceptable amount in comparison with other studies. Moreover, studying the drift variations for 20 days reveals the maximum drift of 1.6%. Finally, according to the present study, the sensor is a suitable candidate for practical applications.