A monopole microwave-assisted electrochemical sensor for the detection of liquid chemicals

Abstract

In this paper, a new sensor structure is presented based on a printed circuit board (PCB) monopole antenna with operating frequency of f=2 GHz. Numerical investigation was performed in order to determine the ethanol alcohol ratio in wine and isopropyl alcohol ratio in disinfectants (sanitizers). Finite Integration Technique (FIT) based commercial high-frequency electromagnetic solver CST Microwave Studio has been used for the simulation study. The loss tangent values and dielectric constants of the samples used in the current study were obtained by KEYSIGHT brand PNA-L N5234A Network Analyzer. The proposed sensor structure was able to greatly differentiate the ethanol alcohol content in the wine and the isopropyl alcohol content in the sanitizer through the return loss values and corresponding graphs. In the design of patch antenna, the electromagnetic permittivity ratios of the samples corresponding to the alcohol ratio and isopropyl ratio are considered and the antenna dimensions along with the working frequency were optimized accordingly. In the related frequency band, permittivity values corresponding to the ethanol alcohol and isopropyl alcohol ratios exhibit a linear variation and make the sensor design possible. According to the obtained results, it was found that the changes in the resonance frequency can be associated with ethanol alcohol and isopropyl alcohol ratio inside the samples. The change of ethanol alcohol amount and isopropyl alcohol in the liquid samples tested at the resonance frequency of patch antenna is proportional to the change in the resonance frequency and they are very close to a linear characteristic.