Sensors for toxic metal ion detection in aquatic environment: current status and future perspectives

Toxic metals such as lead, cadmium, arsenic, mercury, and chromium pose serious environmental and health risks through water contamination. While conventional laboratory-based techniques offer high accuracy, they are often costly, time-consuming, and not suitable for real-time monitoring. Recent advances in sensor technologies provide portable, rapid, and cost-effective alternatives. The present work highlights the progress in electrochemical sensors, semiconductor devices such as ISFETs and AlGaN/GaN HEMTs, and nanomaterials for real-time and on-site monitoring of toxic metal ions. However, challenges remain in achieving long-term stability, reproducibility, and selectivity in continuous water analysis. Future opportunities in integrating these sensors with microfluidics, IoT connectivity, and artificial intelligence for automated data analysis, predictive diagnostics, and field-deployable platforms. This review provides a critical overview of current technologies, challenges, and opportunities, outlining pathways toward next-generation sensing systems for effective water quality monitoring.