Acoustic Wave Sensor Based on Piezomagnetic Phononic Crystal

The propagation of longitudinal acoustic waves in a 1D phononic crystal (PnC) contains a piezomagnetic material (Terfenol-D) as a defect layer is analyzed and discussed theoretically. A resonant mode was generated inside the phononic band gap when the piezomagnetic material thickness becomes around its half wavelength. The present results revealed that the frequency of the generated resonant mode can be controlled by applying an external magnetic field. In addition, the resonant mode is shifted towards higher and lower frequencies by applying an external pressure on the PnC structure. The simulated results are very valuable in the application of sensors measuring magnetic fields and in the early detection of building cracks.