Chemical Liquid and Transformer Oil Condition Sensor Based on Metamaterial-Inspired Labyrinth Resonator

Abstract

In this study, the labyrinth resonator based chemical liquid and transformer oil condition sensor are presented in a microwave frequency range both numerically and experimentally. The transmission coefficient is observed by the magnetic coupling between the transmission line and resonator which also contain a sensing layer. The sensor structure is tested with the ethanol-water mixtures, methanol-water mixtures and different kind of pure chemical fluidics. In addition, the proposed sensor is used for distinguishing the waste and clean transformer oil sensitively. In the chemical liquids sensing study, linear response characteristics of the sensor have been investigated by the resonance frequency shifts for ethanol-water and methanol-water mixtures. The frequency shifts for each 10% steps of ethanol and methanol content have been monitored as about 25 MHz and 15 MHz, respectively. In the transformer oil condition sensing study, non-destructive methods have been used for providing the long term stability of the sensor structure. In addition, the measured response time between the signal applied from the input port and observation of the transmitted signal from the output port is around 5ns. This value is consistent with the period of the applied signal and the length of the receiver/transmitter cables and the sensor circuit.