Tunable sensing properties of a Helmholtz resonator array featuring a central defect cell with four lateral ducts

Acoustic band gap waveguide structures with resonant modes open up a new and original avenue of research in the field of detection. This paper focuses on using a structure of Helmholtz resonators parallel to lateral duct with a central defect cell as a high-sensitivity harmful gas sensor. The numerical analysis was carried out using the finite element method based on a COMSOL Multiphysics simulation. A central defect waveguide containing four lateral ducts leads to the emergence of a localized resonant mode, the positions of which can be controlled by modifying the acoustic properties of the gas samples and the geometric dimensions of the system. This resonance peak reaches a very high transmission intensity in the acoustic band gap, between 92% and 100%, for all the gas samples, reflecting the strong localization of the acoustic waves in the defective cell and therefore, good acoustic energy transfer performance at specific frequencies. Various geometric configurations were analyzed as part of this study in order to determine the optimum parameters of the sensor using the propane sample with air. Under optimal conditions, the sensor recorded a sensitivity of 3.8 Hz.s.[Formula: see text], a high figure of merit of 380.7 s[Formula: see text], and a very exceptional quality factor of 129,422. These characteristics reveal a significant improvement in the efficiency of detecting leaks of harmful gases into the air using the proposed sensor. Furthermore, the sensor exhibits significant peak shift linearity with sound speed, reflecting a very stable sensitivity in all gas samples. Thanks to these important results and the design simplicity, the proposed model of parallel resonators with a central defect can be exploited mainly for gas sensors and powerful detection applications.