Phononic Crystals and Applications

摘要

Optical and acoustic band gap materials, so-called photonic and phononic crystals, belong to the group of metamaterials and provide a novel and alternative platform for sensing material properties in small cavities. The sensor employs specific transmission peaks to determine properties of a component that builds the photonic or phononic crystal. We here concentrate on phononic crystal sensors. One typical arrangement of band gap materials consists of periodically arranged holes in a solid matrix. The peak used for sensing is usually created by introducing a defect into the otherwise regular structure. Such a transmission peak results from a resonant mode created by the defect. The value of interest changes the acoustic properties of the defect and thereby wavelength or frequency of the resonant defect mode. Transmission or reflection coefficients are therefore appropriate parameters for measurement. A (micro)fluidic channel may act as a defect on the one hand and part of the analyte delivery system on the other.