Two-dimensional mechanical synchronous motion modulation with electrostatically driven MEMS actuators for magnetoresistive detectivity enhancement

Magnetoresistive (MR) sensors have emerged as promising candidates for miniaturized, high-performance magnetic sensing applications. However, their performance in low-frequency magnetic field detection is severely limited by intrinsic 1/f noise. To address this challenge, magnetic flux modulation technology that utilizes magnetic flux concentrators (MFCs) and micro-electro-mechanical systems resonators has been proposed to suppress the 1/f noise. In this study, a mechanical synchronous motion modulation (MSMM) architecture is introduced, which integrates MFC motion modulation (MFCMM) with MR element longitudinal motion modulation (MRLMM). The proposed MSMM architecture achieves mechanical synchronization of dual MEMS resonators through microlever couplings and chevron-type (V-shaped) actuators, eliminating the need for complex synchronous phase-locked loop circuits. Theoretical analysis and finite element method simulations were conducted to comparatively evaluate the modulation efficiencies of MSMM, MFCMM, and MRLMM. The results demonstrate that MSMM significantly improves magnetic field modulation efficiency, thereby enhancing the low-frequency detectivity of MR sensors. The designed MSMM actuator has been successfully fabricated, exhibiting a resonant frequency above 10 kHz (the typical corner frequency of the 1/f noise spectrum) and enabling frequency tuning through applied bias voltage. These findings demonstrate the effectiveness of the MSMM technique and highlight its potential for improving the low-frequency magnetic detection performance of MR sensors.