A Multichannel Solid-State Potentiometric Sensor Array for Heavy Metal Ions

Heavy metal ions are common environmental contaminants that threaten aquatic ecosystems and human health. However, conventional analytical techniques often require expensive instrumentation and complex sample pretreatment. This work presents a peptide-based multichannel solid-state potentiometric microelectrode array for simultaneous detection of Cu²⁺, Cd²⁺, and Pb²⁺. The array consists of one shared Ag/AgCl reference electrode and three groups of gold indicator microelectrodes (10 μm in diameter), with each group containing three parallel electrodes for replicate measurements. Each group is functionalized with a distinct peptide receptor specific to one target metal ion. The proposed array exhibits near-Nernstian responses and good selectivity against common interfering ions. Practical applicability is demonstrated by analyzing spiked lake water samples under a fixed chloride condition, with recoveries ranging from 94% to 105%. This work provides a miniaturized, reproducible, and versatile platform for simultaneous potentiometric detection of multiple heavy metal ions, and the peptide-based recognition strategy can be extended to other targets by simply replacing the peptide sequences.