Chipless RFID Sensing System for Precise Ethanol Determination in Alcoholic Solutions

The paper presents a new methodology to assess the ethanol content in water solutions. The system exploits a microwave resonator embedded in a polycarbonate sampling cell. The resonator frequency depends on the ethanol percentage and is monitored in real-time through a non-contacting probe. The method shows a precision better than 1% in ethanol percentage in the range of 1–30%, but can be applied also outside this range. Moreover, the methodology can be further improved or adapted for the analysis of other types of aqueous solutions or liquid mixtures upon evaluation of their dielectric properties.