Batch Preparation of Multi-parameter Sensor for Online and In-situ Monitoring of Tap Water

Abstract

The safety of drinking water is the most basic safeguard for the human survival. In-situ and on-line monitoring of tap water is considered an effective method to reduce the harm of tap water pollution, caused by pipeline rupture or leakage. However, a sensing device of the quality of tap water with the characteristic of anti-cross interference, in-situ, batch-fabrication always is a challenge issue. In this paper, a multi-parameter integrated micro-nano sensor, monitoring six key daily inspection indicators, is designed and prepared by MEMS technology on silicon substrate. By fabricating an all solid thin-film Ag/AgCl reference electrode, employing electrochemical stable/active Pt/Au/PbO₂/IrO₂ as the working/counter electrode and verified the effectiveness of as-fabricated sensor by pH/COD/Free Chlorine/Conductivity/Temperature detection, the sensor demonstrates acceptable limit of detection, desirable linearity and competitive accuracy. In addition, a miniature turbidity sensor is fixed on another side of the substrate, which can accurately distinguish turbidity changes of 0.1 NTU in the range of 0-1 NTU in dark environments. Particularly, a flow velocity detection unit is fabricated to avoid the data deviation by water flow fluctuation. By placing the electrode array in a tiny area (17*19*0.6 mm), a significant improvement in data accuracy is discovered for 9% after cross interference compensation. Finally, a circuit system is developed to assist as-proposed sensor in online and continuous monitoring of the tap water in pipeline. So, the interesting sensing behavior indicate that this work developed a competitive device for tap water online monitoring in pipeline.