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 magnetoelectric (ME) coefficient and the high quality factor of the layered 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-5 A and an axially magnetized magnetostrictive Fe 81 Ga 19 (FeGa) tube. The experimental results show that at a resonant frequency of 71.8 kHz, the sensor’s sensitivity reaches 2.83 × 10 6 V T −1 , with a large bandwidth of 800 Hz and a limits of detection of of 92 fT. A magnetic field intensity of 93 pT is detected at 10 Hz under magnetic frequency conversion 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.