Phononic crystal locally-resonant cavity for detecting vinegar acidity

Abstract

In this study, a highly sensitive and accurate phononic crystal-based sensing method was proposed. Our proposed idea has been studied numerically to identify the allowed and unallowable vinegar. The main difference between allowed and unallowable vinegar is the concentration of acetic acid dissolved in water. Therefore, the designed sensor must be able to accurately separate and sense the different percentages of water-soluble acetic acid. The proposed design consists of a periodic and regular array of air holes on the steel substrate, with the engineered defects idea for sound wave propagation and resonance to sense the different output waves in it. For different percentages of the acetic acid in the vinegar mixture, the resonance of propagating wave in the sensor part of the structure will cause a single frequency with a sharp peak corresponding to a certain amount of acetic acid concentration at the sensor output. Then, by changing even one percent concentration in the water-soluble acetic acid, the frequency peak will shift from the previous state. Finally, by studying the output frequency peaks, it is possible to determine the concentration of acetic acid in the vinegar. This method is very useful for detecting fraud in vinegar. The proposed design has the ability to separate 0% to 100% water-soluble acetic acid concentrations (vinegar mixture) in one percent steps with the high quality factor of 40000. Also, in this work, laboratory test challenges like fabrication tolerance and mixture losses effect are investigated which shows the high reliability.