Ultra-sensitive detection of lead Ions through Portable sensor technology for enhanced environmental monitoring

Toxic heavy metal ions (HMI), prevalent in industrial waste contaminating river water, pose a significant threat to living organisms, causing debilitating diseases and potential fatalities. Therefore, monitoring these toxic elements in water, is of utmost importance. Various techniques have been explored in this direction, including spectroscopic, optical, Micro-Electro-Mechanical (MEMS) - based, Field effect transistor (FET) - based, and electrochemical methods. While offering advantages such as high sensitivity and fast response, these methods often need more portability, require skilled operators, and involve expensive sample preparation. In response, considerable research is underway to develop portable sensor systems for detecting toxic HMI. This study contributes to this effort by proposing a simple and easily fabricated chemiresistive sensor for detecting lead ions (Pb ²⁺ ). The designed sensor utilizes graphene oxide (GO), a 2-dimensional material, for transduction and thiol for the selectivity of Pb ²⁺ . Two different thiols, glutathione and 2,5-Dimercapto-1,3,4-thiadiazole (DMTD), are employed, widely used for detecting Pb ²⁺ using other techniques but not with the simplicity proposed here. This sensor can simultaneously detect specific HMI from three samples or three HMI from a sample. Its performance is noteworthy, providing a detection limit 26.5 pM lower than the 48.3 nM standards set by many organizations. A readout circuit is designed to measure the sensor's resistance, calibrate it based on the concentration of Pb ²⁺ , and transmit data wirelessly, enhancing its applicability in remote monitoring.