A Smart Sensing Node for Pervasive Water Quality Monitoring with Anti-Fouling Self-Diagnostics

Abstract

A novel impedance micro-sensor measuring with 0.5 μm resolution the thickness of undesired chemical or bacterial films fouling the surfaces of in-line probes, monitoring water ducts, is presented. The circuit for lock-in impedance detection (operating at 5 MHz, 10-bit resolution) is illustrated. It is embedded in a multi-sensor IoT water quality monitoring node, enabling self-diagnostics and on-demand maintenance. The credit-card-sized board features pH, temperature, 4 conductivity probes and the film monitor, along with anti-bubble actuation and wireless GSM transmission. The additional power consumption added by the sludge sensor is only 5% of the total.