A Solid-State Nafion-Coated Screen-Printed Electrochemical Sensor for Ultrasensitive and Rapid Detection of Copper Ions in Water

Copper is essential for various biological functions, but elevated levels in water can pose serious health risks. In this work, we introduce a novel electrochemical sensor designed for the highly sensitive and selective detection of copper ions. The sensor is based on a screen-printed platinum working electrode coated with a solid-state Nafion layer. Compared to previous platinum-based sensors, this design demonstrates enhanced sensitivity, a wide linear detection range (1 µM to 10 mM), and an exceptionally low limit of detection (1 nM). It also offers a rapid response time of 3–6 s, strong selectivity, and excellent stability. Interference from common metal ions such as Cr2+, Zn2+, Mn2+, Pb2+, and Fe2+ was minimal, with signal deviations remaining below 2%, and performance remained consistent across varying anion concentrations, showing less than 1% deviation. The use of Nafion as a solid-state electrolyte successfully overcomes challenges typically associated with traditional silver-based reference electrodes. These characteristics make the sensor a reliable and practical tool for the rapid, on-site monitoring of water quality.