Conduino: Affordable and high-resolution multichannel water conductivity sensor using micro USB connectors

The possibility of using the gold-plated pins of micro-USB connectors as electrodes with sub-mm separation for water conductivity monitoring is here proposed and experimentally demonstrated. Thanks to the ubiquitousness and affordability of these shielded, 4-wire cables, this solution aims at representing an alternative to expensive and delicate glass-based platinum probes, normally used in the study of stratified flows. We present also the design of Conduino, an open platform custom-tailored to measure the impedance of four of these probes. The performance of the full instrument demonstrated here (0.1-15 S/m conductivity range, 1% accuracy, 0.1% resolution and 11 ms sampling time) make it very promising for both fluid dynamics and environmental monitoring applications.