Microfluidic electrochemical sensor with lead ion-imprinted polymer membrane for selective trace lead detection in water

Lead contamination in water remains a critical global concern due to its toxicity and persistence. We present a microfluidic sensor that integrates a stand-alone lead ion-imprinted polymer (Pb-IIP) membrane for selective lead detection. Synthesized in situ with Pb(II) as the template, methacrylic acid as the monomer, and 8-hydroxyquinoline as the ligand, the membrane acts as a selective affinity element embedded between non-functionalized electrodes. Leveraging imprinted cavity sites and the Pb-IIP's chemical affinity, the integrated sensor demonstrated heightened lead ion sensitivity, achieving a detection limit of 7.3 ppb and consistent quantification up to 100 ppm. Detection responses were 6.1-fold higher than the membrane-less sensor, 1.5-fold higher than the MAA-based non-imprinted polymer (NIP) sensor, and 13-fold higher than the acrylamide (AAM)-based NIP sensor. The Pb-IIP membrane also differentiated Pb(II) from Cd(II) and Zn(II), with Pb(II) responses being 12.5 % to 69.4 % higher than other ions. Validation with unfiltered municipal tap water yielded recoveries between 96.6 % and 109.0 %, with relative standard deviations below 7 %. These results demonstrate regulatory-relevant detection performance using a low-cost, easily fabricated platform suitable for future adaptation to portable, field-deployable systems. A low-cost microfluidic sensor integrates a stand-alone Pb-ion imprinted polymer (Pb-IIP) membrane for selective trace lead detection in water. Pb²⁺ ions bind selectively to imprinted cavities, generating a stronger electrochemical response than Cd²⁺, Zn²⁺, and blank controls. • Microfluidic sensor with stand-alone Pb-IIP membrane for lead detection. • In-situ synthesized Pb-IIP enables selective trace Pb 2+ sensing in water. • Strong Pb 2+ selectivity in single-ion, multi-ion, and real water samples. • Low-cost, adaptable sensor design for point-of-need heavy metal testing. • Validated in municipal water: 96.6–109.0 % recovery, <7 % RSD across replicates.