Heavy metals biosensor based on defective one-dimensional phononic crystals

In recent years, the detection of water pollution with low levels of heavy metals has attracted the great attention
of many researchers as a result of the imminent danger of this type of pollution to all mankind. Meanwhile, we
introduce a theoretical approach based on the one-dimensional phononic crystals (1D-PnCs) with a central defect
layer as a novel platform for the highly sensitive detection of heavy metal pollution in freshwater. Therefore, the
creation of a resonant peak in the transmittance spectrum related to this defect layer is highly conceivable. In this
regard, the detection of cadmium chloride (CdCl2) as a dangerous, toxic, and extremely hazardous heavy metal
could be investigated based on the small displacement in the position of this resonant peak with the changes in
the CdCl2 concentration. Notably, any change in CdCl2 concentration has a direct impact on its acoustic properties.
The theoretical framework of our research study is essentially based on the 2 × 2 transfer matrix method
and the acoustic properties of the constituent materials as well. The optimization of all sensor parameters represents
the mainstay of this study to get the best sensor performance. In this regard, the proposed sensor has a
remarkably high sensitivity (S = 1904.25 Hz/ppm) over a concentration range of 0 – 10000 ppm. In addition, the
sensor has a high quality factor (QF), and figure of merit of 1771.318, and 73529410􀀀 5 (ppm􀀀 1), respectively.
Finally, we believe this sensor could be a key component of a feasible platform for detecting low concentrations
of different heavy metal ions in freshwater.