A Novel E-E-Type Electrically Modulated Magnetoelectric Sensor for Extremely Low-Frequency Magnetic Field Detection

The detection of weak extremely low-frequency magnetic fields has always been a challenge, as magnetic detection equipment is affected by 1/f noise. Magnetoelectric (ME) sensors can compensate for the above shortcomings through frequency modulation, but current modulation methods rely on carrier coils or pickup coils, which not only bring crosstalk noise but also require a large amount of energy consumption. Therefore, we have introduced an innovative method of electric modulation frequency conversion and developed an E-E-type ME sensor (EEMS), which eliminates the necessity of the coil. Through simulation, we have verified that EEMS can generate the carrier magnetic field required for frequency modulation under input excitation and provided a theoretical explanation for this phenomenon. Experimental results demonstrate a close correlation between the EEMS's sensitivity and excitation voltage. Specifically, at 0.6 Vpp, it achieves a remarkable sensitivity of 7616 V/T for a 1-Hz magnetic field, with a low detection limit of 174 pT and an equivalent magnetic noise (EMN) as low as 16.58 pT/root Hz. Moreover, the EEMS boasts a magnetic field amplitude resolution below 4.35 nT and a magnetic field frequency resolution of 10 mHz. This research designs a low-noise and high-sensitivity electric modulation ME sensor, providing a new method for detecting extremely low-frequency (ELF) magnetic fields.