Batch microfabrication of highly integrated silicon-based electrochemical sensor and performance evaluation via nitrite water contaminant determination

Electrochemical sensors play a key role in the monitoring of pollutants in water due to their high-sensitivity and short-response-time etc. However, the stability for long-term sensing testing and hard to mass production of electrochemical sensors always is a challenge issue. In this paper, a novel silicon-based electrochemical sensor that can be mass-produced via the microfabrication technique/MEMS is proposed. By fabricating a liquid conjunct Ag/AgCl reference electrode, employing relatively electrochemical stable Au as the working electrode/counter electrode and verified the effectiveness of as-fabricated sensor by nitrite detection, the micro-fabricated electrochemical sensor demonstrates acceptable limit of detection, desirable linearity and good resistance to other interference substances. Particularly, satisfactory long-term stability was witnessed for the proposed sensor. After continuously operated for 19 days, the sensor still kept 94% response signal when compared with that of the value obtained at its initial state. What's more, by employing the mass-production technique, favorable response consistency and high reproducibility was witnessed, offering the opportunity of mass-producing the proposed sensor in future. And the high consistency and satisfactory long-term stability of as-proposed sensor indicated that the study on mass production electrochemical sensor fabricating by MEMS was a successful attempt. It is anticipated that the proposed sensor configuration will provide an alternative strategy to design future low power and reliable mini-sensor for water contaminants monitoring. (C) 2020 Elsevier Ltd. All rights reserved.