Highly Sensitive Detection of Pb²⁺ in Water Using Phase Shift-Based Capacitive Sensor Immobilized With Graphene Oxide

Lead ion (Pb ${}^{{2}+}$ ) contamination in water is a critical environmental and public health issue, posing serious risks to human health even at low concentrations. While conventional detection methods, such as atomic absorption spectroscopy (AAS) and inductively coupled plasma mass spectrometry (ICP-MS), provide high sensitivity, their reliance on sophisticated equipment limits their accessibility for broader use. This study introduces a novel phase shift-based capacitive sensor using interdigitated electrodes (IDEs) immobilized with graphene oxide (GO) for Pb ${}^{{2}+}$ detection. The sensor leverages GO’s large surface area and oxygen-containing functional groups to achieve a detection limit of 1.7 ppm and a sensitivity of 0.0556°/ppm. Measurements revealed a strong linear correlation (R ${}^{{2}}~\gt 0.946$ ) between phase shift and Pb ${}^{{2}+}$ concentration over a wide range (10–400 ppm), highlighting the sensor’s linearity and reproducibility. This approach offers a simplified and cost-effective alternative to existing methods, supporting water quality monitoring and industrial safety applications.