A portable electrolyte concentration and driven microfluidic electrochemical sensing chip for rapid in-situ detection of trace lead ions

Abstract

Heavy metal ions can cause significant damage to food, environment and human health because of their high toxicity, bioaccumulation and non degradability. Therefore, a highly portable microfluidic sensing system was developed for rapid on-site detection of heavy metal ion (Pb²⁺ was chosen as a model). Herein, the microfluidic electrochemical sensor utilized the photothermal evaporation effect to accelerate evaporation of water, resulting in formation of concentrated electrolyte solution. Moreover, the photothermal effect can trigger the occurrence of thermocapillary convection, accelerate the capture of Pb²⁺ and promote the electrochemical oxidation-reduction process, which can eliminate traditional pre-enrichment process and further improve the electrochemical signals. And the 3D AgNPs-RGO-Ni(OH)₂@NF with porous and photothermal properties was prepared as a working electrode by one-step hydrothermal method to provide more active sites and electron transfer channels, and coupled with photothermal effect to improve detection performance. The sensor possessed a low detection limit of 0.61 ng/L and a wide detection range (0.001 μg/L–2500 μg/L) for Pb²⁺, and has also achieved excellent test results in actual and spiked samples detection (tap water, fish and human serum). The microfluidic sensor integrated a stable and easy-to-operate photothermal evaporation system into a highly integrated 3D printing device, which was compact, simple and portable, and has broad prospects in the field of heavy metal ions detection.