Signal-noise analysis of miniaturized delta-E effect magnetic field sensors

Abstract

Delta-E effect sensors developed for detecting small amplitude and low-frequency magnetic fields have shown potential for miniaturization. However, a comprehensive signal-and-noise analysis of such miniaturized sensors is lacking. Here, we present an in-depth study of the key performance characteristics of sub-millimeter-sized delta-E effect sensors with a double-wing resonator geometry. Several resonance modes are evaluated for their sensitivity, noise, and limit of detection (LoD) as functions of the excitation voltage amplitude and magnetic bias flux density. We identify and discuss the optimal conditions for sensor operation and compare the performance to that of the reported macroscopic devices. While all investigated resonance modes behave qualitatively similar, quantitative differences in signal and noise lead to an almost sevenfold difference in LoD s. The performance is limited by magnetic noise at large excitation amplitudes and, unlike reported macroscopic delta-E effect sensors, by noise from the excitation signal and charge amplifier at low excitation amplitudes. The best performance is achieved in the third resonance mode excited at 683 kHz with a LoD≤7.4±3 nT/Hz between 10 and 1000 Hz and a minimum of 2.8 nT/Hz at 195 Hz. This demonstrates an improvement over previously reported values for miniaturized delta-E effect sensors in this frequency range. Moreover, the sensors show a −3 dB bandwidth of ≈440 Hz, which is significantly wider compared to macroscopic delta-E effect sensors. Reducing electronic noise and employing advanced magnetic multilayers can further improve the LoD, making these miniaturized sensors promising candidates for compact arrays.