Abstract
In this study, a dual-mode Metglas/Pb(Zr,Ti)O3 magnetoelectric (ME) sensor was prepared for measuring weak magnetic fields. It is interesting to note that this ME sensor can work at alternating current (AC) and direct current (DC) dual-modes with high field resolution. In AC mode, a very accurate AC magnetic field resolution of 0.8 nT was achieved at a mechanical resonance frequency of 72.2 kHz; moreover, the operating frequency band for resolution better than 1 nT is as wide as 3.4 kHz. We proposed a DC bias field perturbation (DBFP) method to detect the DC magnetic field using lock-in amplifier technology. As a result, an ultra-accurate DC field resolution of 0.9 nT with noise power spectral density as low as 100 pT/Hz was obtained in the studied ME sensor via the DBFP method. The dual-mode ME sensor enables simultaneous measurement for DC and AC magnetic fields with wideband and accurate field resolution, which greatly enhances the measurement flexibility and application scope.
Highlights
We proposed a direct current (DC) bias field perturbation (DBFP) method to detect the DC magnetic field using lock-in amplifier technology
The weak magnetic field measurement methods are mainly based on the Hall effect, anisotropy magnetoresistance (AMR), giant magnetoresistance (GMR), giant magnetoimpedance (GMI), tunneling magnetoresistance (TMR), proton precession magnetometer (PPM), atomic magnetometer (AMM), flux-gate meter (FGM), superconducting quantum interference device magnetometer (SQUID), and magnetoelectric coupling sensor (ME sensor)
This study demonstrates that, on one hand, the DBFP method is an excellent method to measure the ultra-low DC magnetic field with an ultra-accurate magnetic field resolution; on the other hand, an ultra-low DC field resolution of 0.9 nT was obtained in the studied ME sensor
Summary
Weak magnetic field detection technology is widely used in industry, medical detection, and military.[1,2,3] With the development of electronic technology and mechanical manufacturing, magnetic field measurement has developed toward miniaturization, electronization, digitization, and automation.[4,5,6] In particular, the detection of ultra-low frequency or direct current (DC) magnetic fields has been urgently demanded in some novel areas, such as magnetocardiogram (MCG), magnetoencephalogram (MEG), geomagnetismaided navigation and positioning, geoscientific prospecting, and underwater/underground objects searching.[7,8,9] Currently, the weak magnetic field measurement methods are mainly based on the Hall effect, anisotropy magnetoresistance (AMR), giant magnetoresistance (GMR), giant magnetoimpedance (GMI), tunneling magnetoresistance (TMR), proton precession magnetometer (PPM), atomic magnetometer (AMM), flux-gate meter (FGM), superconducting quantum interference device magnetometer (SQUID), and magnetoelectric coupling sensor (ME sensor). In order to maintain high sensitivity at mechanical resonance and be competent for ultra-low frequency measurement simultaneously, it is necessary to explore the frequency conversion technology. The alternating current (AC) magnetic sensors show extremely low noise at high frequency, measurements of ultra-low frequency and DC magnetic fields are needed in some important areas such as MCG, MEG, geomagnetism-aided navigation and positioning, geoscientific prospecting, and underwater/underground objects searching. All of these areas require the measurement of magnetic field signals at ultra-low frequency below 100 Hz or even DC magnetic field. Parameters d31 (pC/N) d33 (pC/N) s33 (m2/N) ρ (g/cm3) ε (F/m) TC (○C) EC (kV/cm)
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