Phononic crystals for sensing FAMEs with demultiplexed frequencies

Abstract

A numerical investigation on a solid-fluid phononic crystal as a sensor-demultiplexer is presented in order to detect MeCs, including Fatty Acid Methyl Esters group materials - a kind of vegetable oil and basically similar to the fossil fuels. The proposed sensor includes a Mach-Zehnder waveguide with two cavities in which the MeCs are embedded. The cavities contain the target sample and act as frequency resonator. The PnC sensor consists of a square periodic inclusions of Water embedded in stainless steel substrate. Water and stainless steel have a good contrast in physical properties. Therefore, it is possible to have a wide bandgap. To evaluate the band structure and transmission spectrum, the finite element method (FEM) is utilized. Also, the section of demultiplexer acts as a frequency separator for the target sample and finally each of MeCs including MeC 10:0, 12:0 and 14:0 can be sensed based on the relevant frequency extracted from different outputs. The final waveguides are made by changing the radius of scatterers. For each branch, the radii of inclusions are designed to achieve various defect modes. Finally, the Mach-Zehnder sensor-demultiplexer has ability to divide 83.354, 83.361 and 83.367 KHz for MeCs 10:0, 12:0 and 14:0, respectively. To the best of our knowledge, this study is the first to propose a phononic sensor with different outputs for the respective frequencies of various sample combinations.