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 (2.25mm2) 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/
$\surd $
Hz and 2.72nT/
$\surd $
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/
$\surd $
Hz when sensing an AC magnetic field at the device resonance. [2022-0158]