Ultra sensitive lorentz force MEMS magnetometer with pico-tesla limit of detection

Abstract

This work presents ultra-high sensitivities for Lorentz Force resonant MEMS magnetometers enabled by internal thermal-piezoresistive vibration amplification. Up to 2400X increase in sensitivity has been demonstrated by tuning the resonator bias current to maximize its internal amplification factor boosting the effective Quality Factor (Q) from its intrinsic value of 680 to 1.14×106 (1675X amplification). For a bias current of 7.245mA, where the sensitivity of the device is maximum (2.107mV/nT), the noise floor is measured to be as low as 2.8 pT/√Hz. This is by far the most sensitive MEMS Lorentz force magnetometer demonstrated to date.