Design of a highly sensitive defect-based 1D phononic crystal sensor for precise magnetic field sensing

This study presents a one-dimensional phononic crystal (PnC) magnetic field sensor comprising alternating layers of Tungsten and PMMA layers with a defect core of Terfenol-D. The designed structure utilizes the transfer matrix method (TMM) to analyze the acoustic wave propagation and magnetostrictive modulation induced by an external magnetic field. The mainstay of the investigated numerical findings is essentially dependent on the use of the shift through the emerged resonant mode to detect the minute variations in the applied magnetic field. Notably, the variations in the elastic modulus of Terfenol-D produce measurable shifts in the defect-mode resonance frequency, enabling magnetic field detection with high precision. Through parametric optimization of layers’ thickness, the sensor achieves a sensitivity of 420 Hz/Oe, a quality factor of 702.75, and a figure of merit of 8.4 × 10 3 . Comparative analysis with recent literature shows that the proposed design offers roughly twice the normalized sensitivity (8.1 ppm/Oe) of existing magnetoacoustic and magnetoplasmonic sensors while maintaining a simpler, experimentally feasible configuration. The influence of fabrication tolerances and damping effects was also examined, confirming a strong robustness to structural and material variations. Despite the investigated results are obtained numerically, the design is compatible with current microfabrication techniques, providing a viable platform for the next generation miniaturized magnetic sensors. Moreover, due to the simplicity of design, tunability, and material compatibility, the proposed structure holds significant promise for the development of compact, robust, and efficient magnetic field sensors in advanced phononic and acousto-electronic applications.