Microfabricated on-chip integrated Au-Ag-Au three-electrode system for in situ mercury ion determination.

In this paper, a new two-step photolithography fabrication method is used for the fabrication of an on-chip integrated two-metal electrode system, with a Ag reference electrode and two gold electrodes used as working and counter electrodes, respectively. Combined with a microfluidic channel, the total detector has the advantages of ease of use, low analyte consumption, fast sensing time and is suited for in situ target metal ion determination. Herein, the three-electrode system was used for Hg(2+) ion measurement, and both the capabilities of Au working and Ag reference electrodes were characterized by using electrochemical techniques. The results show that the as-prepared on-chip integrated electrochemical detector performed with high sensitivity and good reproducibility in Hg(2+) determination. The detection range extends from 10 to 1000 ppb with a good linear correlation, and the detection limit is low to 3 ppb (S/N = 3). Our method provides a rapid and effective, miniaturized electrochemical analysis platform in Hg(2+) measurement and demonstrates great potential for the application of in situ or on-line mercuric pollutant analysis.