Pyrolytic glassy carbon and graphene composite-based heavy metal sensor with a valveless micropump

A microfluidic sensor with high sensitivity and low cost was developed for detection of heavy metal ions. The sensor utilizes a novel glassy carbon/graphene composite electrode synthesized by layer-by-layer self-assembly and subsequent pyrolysis. The electrode exhibits low overpotential enabling detection of almost any heavy metal ions in aqueous solutions. The incorporation of graphene results in high sensitivity. To enhance mass transfer and sensitivity, a valveless micropump was integrated into the system, achieving two orders of magnitude higher sensitivity and a detection limit of 20 ppt for lead and 100 ppt for cadmium. The sensor was employed for simultaneous detection of lead and cadmium in water, documenting the multiple influences of the two heavy metal ions. The sensor achieved consistent results when it was applied to environmental water. Additionally, a neural network model was employed for data analysis.