Ultrasensitive micro sensor based on layer-by-layer self-assembled graphene and bismuth nanoparticles for trace lead ions determination

An ultrasensitive micro sensor for the detection of trace lead (II) is fabricated by mixed dispersion solution of bismuth nanoparticles (Bi NPs) and PDDA, and layer-by-layer self-assembled (LBL SA) with graphene (G) suspension solution on a micro gold electrode. The LBL SA G-Bi NPs sensor performance has been greatly enhanced in determination of Pb (II) using anodic stripping voltammetry (ASV). Compared with a sensor without surface modification, the sensor's stripping peak potential decreased from −0.520 V to −0.564 V, and its peak current increased from 1.227 μA to 8.372 μA. Compared with a sensor modified by LBL SA G (without Bi NPs), stripping peak potential decreased from −0.548 V to −0.572 V, the sensor's peak current increased from 0.284 μA to 1.263 μA. This sensor's limit of detection (LOD) of Pb (II) was achieved as 0.078 ppb with a sensitivity of 1.061 μA/ppb. This simple but effective graphene-metal nanocomposites construction method can be widely used in the development of highly sensitive ion sensor.