Distinguishing Liquid Solutions With Alcohol Using Electrical Impedance Measurements: Preliminary Study for Food Safety Applications

Methods for identifying contaminants in liquids (such as wine) typically require laboratory analyses of samples using precision equipment, which is expensive in terms of both time and required resources. Therefore, there is a need to identify alternative measurement approaches to reduce the cost in terms of equipment, personnel, and time. One sensing approach to characterize liquid properties and potentially identify contaminants is electrical impedance spectroscopy (EIS). In this work, the electrical impedance of 25-mL samples of three solutions with alcohol (plum distillate, isopropyl alcohol, and winter windshield solution) and a control sample of distilled water were measured using a Keysight 4294A. The liquids with alcohol content (plum distillate, isopropyl alcohol, and winter windshield solution) have lower impedance magnitude in the frequency band below 100 kHz, with specific values of 139, 76, and 7 $\text{k}\Omega $ at 40 Hz, compared to the reference distilled water sample (approximately 315 $\text{k}\Omega $ ). This suggests that solutions with alcohol (and other chemicals) have increased conductivity in comparison to the distilled water and that impedance may be a suitable approach to differentiate liquids with and without contaminants.

I. Introduction

The investigation of sensing technologies for monitoring foods and liquids with a specific focus on safety has increased in both attention and importance in recent years. The aim of this line of investigation is to develop techniques to identify contamination accurately and reliably in foods and liquids prior to their sale or consumption to prevent potential illnesses. Recent research has developed electronic sensing systems to emulate the human senses of taste (e.g., electronic tongue) and smell (e.g., electronic nose) to identify and classify food sensory and safety characteristics [1], [2].