A Dual Concentric Coil-Based Contactless Sensor for Water Quality Assessment in a Pipeline

Abstract: In many urban regions, household drinking water is sourced either from groundwater or supplied by desalination plants, where seawater is treated to make it potable; in both cases, continuous monitoring of salinity is essential to ensure water quality. In this talk, the development of a contactless, dual-coil inductive method for measuring water salinity that can be integrated directly into a pipeline without exposing electrodes or sensing elements to the fluid will be presented. The proposed sensor employs two concentric coils: an inner sensing coil magnetically coupled to the water column and an outer readout coil, placed outside the pipe, connected to the measurement electronics. Conventional inductive sensors typically rely on a single coil, which suffers from reduced sensitivity in thick-walled pipelines and may require intrusive electrical connections when coils are placed inside the pipe, thereby compromising reliability and pressure integrity. The proposed approach overcomes these limitations by maintaining a fixed magnetic coupling geometry and exploiting conductivity-dependent phase variations near the coupled LC system’s parallel resonance. Changes in water conductivity modify the effective inductance of the inner sensing coil through eddy-current interactions, which in turn influence the phase response of the resonant system. The phase shift is extracted using a phase-sensitive detector (PSD) tuned to the excitation frequency, enabling high sensitivity with low-power consumption. A prototype sensor has been fabricated and experimentally evaluated over a range of water conductivity levels. The results demonstrate clear and repeatable phase variations with salinity, highlighting the suitability of the proposed method for noncontact electrical conductivity (EC) measurement and inline water quality monitoring in domestic and industrial pipelines. The details of the development will be presented in the talk.

Event Details
Title: A Dual Concentric Coil-Based Contactless Sensor for Water Quality Assessment in a Pipeline
Date: September 28, 2026 at 04:00 PM
Venue: Google Meet ( meet.google.com/cyu-yxvn-wgb)
Speaker: Mr. Shibi Chakravarthi (EE20S143)
Guide: Dr. Boby George
Type: MS seminar