High-Q Factor, Multiferroic Resonant Magnetic Field Sensors and Limits on Strain Modulated Sensing Performance

Magnetic fields produced by the body can provide information for medical diagnoses, patient monitoring, and robotic control. Measuring biomagnetic signals locally allows for an external sensing mechanism that is non-invasive and non-contact. Despite these advantages, current sensing systems are either prohibitively large, consume excessive power, or both when applied to on-body applications. This study explores how multiferroic systems can provide an alternative to current biomagnetic sensing platforms. While maintaining a very small die size (2.25mm (2)) and low power consumption (13mW), multiferroic resonant MEMS magnetometers can provide high sensitivity and low noise at room temperature. Two resonant plate designs operating in the MHz regime are explored, implementing a strain modulation technique to upconvert low frequency magnetic field signals to the resonance band of the plates, utilizing the high device Q factors. When operated below the Duffing limit, sensitivities of 58.4mA/T and 37.7mA/T with resolutions of 5.03nT/ root Hz and 2.72nT/ root Hz, respectively, were observed for the two devices. Without electric modulation, the large sensor design shows a sensitivity of 1.56A/T and a resolution of 2pT/root Hz when sensing an AC magnetic field at the device resonance. 2022-0158

Automated summary

Magnetic fields produced by the body have potential applications in medical diagnoses, patient monitoring, and robotic control. However, current sensing systems for biomagnetic signals are either large in size, consume excessive power, or both, when applied to on-body applications. This study investigates the use of multiferroic systems as an alternative to current biomagnetic sensing platforms, showing that multiferroic resonant MEMS magnetometers can provide high sensitivity and low noise while maintaining a small die size and low power consumption. The experiment demonstrates the effectiveness of strain modulation technique in upconverting low frequency magnetic field signals to the resonance band of the plates, achieving sensitivities and resolutions suitable for biomagnetic sensing.