Low-Noise Potentiostat Circuit for Electrochemical Detection of Heavy Metals or Metalloids

Detection and quantification of water contaminants, such as arsenic (As), mercury (Hg), and copper (Cu), require highly sensitive and inexpensive portable devices. In this article, a low-noise portable potentiostat circuit is proposed for the simultaneous detection of As(III), Hg(II), and Cu(II) at the ppb level. This design neither requires external devices such as personal computer (PCs) or smartphones nor any dedicated software for data acquisition. The overall circuit's noise is analyzed to reduce the noise so that measurement precision improves. The proposed circuit has a noise floor of 1.6 nV/root Hz @ 10 kHz and the simulated root-mean-square (RMS) noise is 900 nV. The practical application of the designed circuit for the detection and quantification of As(III), Hg(II), and Cu(II) is demonstrated using a gold (Au)-coated electrode. The reliability of the measurement is verified by comparing it with commercial AUTOLAB potentiostat. The results indicate that the proposed portable system is reliable, and low concentration (in ppb) of As(III), Hg(II), and Cu(II) in water can be measured quantitatively.