Bismuth Functionalized Inkjet-Printed Electrochemical Sensor for Aqueous Lead (II) Detection

This article introduces a sensitive, selective, and reusable 3-D bismuth functionalized inkjet-printed shape memory polymer (SMP) incorporated electrochemical sensor (ECS) for detecting lead (II) in aqueous solution, that is, deionized water, tap water, and river water. The reported ECS comprises a bismuth deposited working electrode (WE), a gold (Au) counter electrode, and a silver chloride (AgCl) reference electrode. Bismuth functionalization was performed through two approaches on the inkjet-printed Au-plated (thickness – $8.24~\mu $ m ±1.42) electrodes: ex situ, involving a full cycle of cyclic voltammetry (CV) process to deposit bismuth – $400~\mu $ g/L bismuth, and in situ, where CV or square wave anodic stripping voltammetry were performed with a lead (II) contaminated aqueous solution diluted with $200~\mu $ g/L bismuth. The limit of detection (LOD) for the bismuth functionalized inkjet-printed ECSs are $0.64~\mu $ g/dL (ex situ) for the bismuth deposited WE ( $13.92\Omega $ . $\Box ~\pm ~1.96$ ) and $1.09~\mu $ g/dL (in situ) for the Au WE ( $4.4\Omega $ . $\Box ~\pm ~0.3$ ). The sensor, designed for miniaturization, exhibits enhanced performance in electrochemical sensing due to its increased effective electrode surface area (EESA) (7.25 mm ${}^{{2}}~\pm ~0.15$ ) despite a reduced lateral surface area (4.19 mm2). An optimized cleaning process and a mathematical model representing the relationship between printed and electrical areas of the inkjet-printed electrodes are presented thoroughly to provide flexibility and certainty of designing different electrochemical and biosensors. Conclusively, the design, fabrication, bismuth functionalization, characterization, and optimization encompassing sensitivity, selectivity, reproducibility, reusability, and cost-assessment of the bismuth functionalized inkjet-printed ECS for aqueous lead (II) detection are delineated in this article in detail.