Spring-integrated low-frequency ME resonator with strong coupling capability and low equivalent magnetic noise

This is the authors' abstract. We don't add key points for this paper.

Resonant magnetoelectric (ME) sensors offer the advantages of high sensitivity and inherent narrow-band filtering capability. However, the development of ultra-low-frequency (ULF) ME resonators combining high mechanical quality factor (Qm), low noise performance, and stable near-ideal boundary conditions remains a significant challenge. In this study, a spring-integrated ULF ME resonator is proposed and systematically investigated. The device consists of an elastic support layer, a piezoelectric layer, and a piezomagnetic layer. The elastic support layer incorporates two meander springs at both ends, creating quasi-free boundary conditions for the central sandwich-structured ME composite and enabling excitation of a high-order bending mode with a substantially reduced resonant frequency. Experimental results confirm the excitation of the third-order bending mode at a low frequency of 1266 Hz, with a calculated Qm of 144.8. In addition, the resonant ME coefficient reaches as high as 1633.5 V/(cm Oe), and the equivalent magnetic noise decreases to 300 fT/√Hz around the resonance frequency, demonstrating great potential for specific-frequency magnetic field detection applications, including signature current identification and underground cable tracing. More importantly, the spring-integrated resonant structure provides fixed boundary conditions and maintains a stable operating frequency during long-term operation.