High-Sensitivity and Wideband Cylindrical Magnetoelectric Sensor for Low-frequency Magnetic Field Detection

Abstract Wideband high-sensitivity detection of low-frequency magnetic fields remains challenging owing to the strong frequency dependence of the ME coefficient and the high quality factor of the layered magnetoelectric (ME) sensors. Here, we proposed a high-performance cylindrical ME sensor and utilize frequency conversion to up-convert the signal to mechanical resonance, thereby enhancing the detection performance for low-frequency magnetic fields. The ME sensor consisted of an axially polarized cylindrical piezoelectric ceramic PZT-5A and an axially magnetized magnetostrictive Fe81Ga19 (FeGa) tube. The experimental results show that at a resonant frequency of 71.8 kHz, the sensor's sensitivity reaches 2.83 × 106 V/T, with a large bandwidth of 800 Hz and a limits of detection (LOD) of of 92 fT. A magnetic field intensity of 93 pT is detected at 10 Hz under magnetic frequency conversion (MFC) with a near-flat frequency response in the range of 5–400 Hz. Moreover, obvious sideband noise appears when the high-frequency magnetic field modulates the signal below 1 Hz, severely affecting the signal-to-noise ratio of the low-frequency signal. Therefore, our sensor exhibits enhanced sensitivity by optimizing the carrier frequency, achieving 220 pT at 1 Hz and 900 pT at 0.1 Hz. Our research has significant implications for the development of highly sensitive low-frequency weak magnetic field detection.