An on-chip electrochemical sensor by integrating ITO three-electrode with low-volume cell for on-line determination of trace Hg(II)

Abstract

In this paper, an on-chip electrochemical sensor was designed by integrating an indium tin oxide (ITO) three-electrode with a low-volume cell, and trace Hg2+ was detected by differential pulse anodic stripping voltammetry (DPASV) after online flow accumulation in the sensor. The working electrode of the ITO three-electrode was composed of in-situ electrodeposited flower-cluster gold nanoparticles (AuNPs) microarray on the surface of the ITO, the reference electrode was Ag/AgCl, and the auxiliary electrode was ITO. The in-situ flow accumulation in the on-chip electrochemical sensor was used to detect the linear range of Hg2+ from 0.63 to 80ppb with a detection limit of 0.11ppb (S/N=3). The sensors had good selectivity towards Hg2+ in the interferences of eight common cations. The recovery rates of 1ppb Hg2+ were 101% in the tap water and 106% in the lake water. Compared with the traditional detection method, the on-chip electrochemical sensor by the in-situ flow accumulation of Hg2+ required low-volume sample and got a more sensitive and stable signal, so it had excellent potential for on-site and on-line detection of mercuric pollutant.