Ultrasensitive Detection of Lead Ions Through Portable Sensor Technology for Enhanced Environmental Monitoring

Toxic heavy metal ions (HMIs), 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, microelectromechanical-system-based, field-effect-transistor-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 letter contributes to this effort by proposing a simple and easily fabricated chemiresistive sensor for detecting lead ions (Pb²⁺). The designed sensor utilizes graphene oxide, which is a 2-D material, for transduction and thiol for the selectivity of Pb²⁺. Two different thiols, i.e., glutathione and 2,5-dimercapto-1,3,4-thiadiazole, are employed and are widely used for detecting Pb²⁺ using other techniques but not with the simplicity proposed here. This sensor can simultaneously detect specific HMI from three samples or three HMIs 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 Pb²⁺, and transmit data wirelessly, enhancing its applicability in remote monitoring.