A Direct AC Cross Conductive Sensor for Milk Quality Measurement.

Milk adulteration by various impurities, such as water, whey, and urea, and some other harmful chemicals is an important issue in different countries in the world. Traditionally, analytical instruments are used for milk quality analysis. These instruments are accurate but these are complex, expensive, inconvenient for field use, and require laborious skilled procedures to get the reading. Portable sensors-based instruments working on direct/indirect transduction phenomena are also reported in the literature. Most commonly, the conductive sensors with selective sensing films are used for detecting the milk impurities but such sensors require calibration and show drift due to aging. There is a need to develop a rapid, accurate, sensitive, and cost-effective simple working detection system. This article presents the theory, design, fabrication, and test results of an accurate and simple working prototype model of an ac cross-conductance sensor for milk adulteration detection. The structure of the sensor has four conductive brass electrodes, arranged in the form of a concentric cylinder, with narrow gaps among them. The sensor was fabricated and tested in the laboratory environment to analyze the quality of 1) drinking water having different total dissolved solids (TDS) and 2) milk having different amounts of impurities, such as water, whey, and urea. The sensor can differentiate between pure and adulterated milk with significant resolution and precision. [ABSTRACT FROM AUTHOR]