A portable microfluidic electrochemical sensing platform for rapid detection of hazardous metal Pb2+based on thermocapillary convection using 3D Ag-rGO-f-Ni(OH)2/NF as a signal amplifying element

Heavy metal pollution is causing a great threat to ecological environment and public health, which needs an efficient strategy for monitoring. A portable microfluidic electrochemical sensing system was developed for the determination of heavy metal ions. Herein, the detection of Pb2+ was chosen as a model, and a microfluidic electrochemical sensing chip relying on a smartphone-based electrochemical workstation was proposed for rapid detection Pb2+ with the assistance of thermocapillary convection result from the formed temperature gradient. The 3D Ag-rGO-f-Ni(OH)2/NF composites, prepared by one-step hydrothermal method without any Ni precursor salt, were used to further amplify electrochemical signals under the synergistic effect of thermocapillary con-vection. The thermocapillary convection could accelerate the preconcentration process and shorten the detection time (save 300 s of preconcentration time). The fabricated system exhibited the exceptional competence for monitoring of Pb2+ range from 0.01 mu g/L to 2100 mu g/L with a low detection limit (LOD) of 0.00464 mu g/L. Furthermore, this portable system has been successfully demonstrated for detecting Pb2+ (0.01 mu g/L to 2100 mu g/ L) in river water (LOD = 0.00498 mu g/L), fish (LOD = 0.00566 mu g/L) and human serum samples (LOD = 0.00836 mu g/L), and the results were consistent with inductively coupled plasma-mass spectrometry (ICP-MS). The pro-posed novel sensing platform provides a cost-effectiveness, rapidly responding and ease-to-use pathway for analysis of heavy metal ions in real samples and shows great potential in point-of-care testing.