3D-printed multiresonant sensor for ultra-low frequency vibration monitoring

Abstract A proof-of-concept accelerometer for ultra-low and low-frequency vibration sensing is presented. The device integrates a high-sensitivity Giant Magnetoimpedance (GMI) sensor with a 3D-printed magnetized resonant structure, based on the low Young’s modulus of polymers and the geometric versatility of additive manufacturing to explore its potential as an alternative sensing approach to conventional piezoelectric sensors in the low-frequency regime. The sensing architecture consists of a serpentine-like PLA resonator combined with a self-manufactured hard magnetic composite of cobalt-doped ferrite nanoparticles Co x Fe 3−x O 4 embedded in a polycaprolactone matrix. Finite Element Method (FEM) simulations were utilized to optimize the geometry, ensuring fundamental resonant modes within the targeted ultra-low-frequency range. Experimental results demonstrate a primary resonant response between 8 and 11 Hz, maintaining high detection reliability even at peak-to-peak acceleration levels as low as 0.05 g. Furthermore, the sensing performance is shown to be highly tunable by adjusting the magnetic nanoparticle loading or remanent magnetization, while the addition of proof masses allows for post-fabrication frequency shifting down to 4.3 Hz. This work demonstrates a low-cost, contactless, and reconfigurable platform for sensing ultra-low and low-frequency vibrations even at low acceleration levels.