Amplitude modulated Lorentz force MEMS magnetometer with picotesla sensitivity. (20th September 2016)

• Record Type: Journal Article
• Authors: Kumar, Varun; Ramezany, Alireza; Mahdavi, Mohammad; Pourkamali, Siavash
• Is Part Of: Journal of micromechanics and microengineering. Volume 26:Number 10(2016:Oct.)
• Publication Date: 2016-09-20
• Subjects: magnetic field sensor -- mems -- picotesla -- thermal-piezoresistive amplification; Microelectromechanical systems -- Periodicals; Micromechanics -- Periodicals; 621.38105
• DOI: 10.1088/0960-1317/26/10/105021
• Languages: English
• ISSNs: 0960-1317

Abstract

Abstract: This paper demonstrates ultra-high sensitivities for a Lorentz force resonant MEMS magnetometer enabled by internal-thermal piezoresistive vibration amplification. A detailed model of the magneto-thermo-electro-mechanical internal amplification is described and is in good agreement with the experimental results. Internal amplification factors up to ~1620 times have been demonstrated by artificially boosting the effective quality factor of the resonator from 680 to 1.14 × 10 6 by tuning the bias current. The increase in the resonator bias current in addition to the improvement in the quality factor of the device led to a sensitivity enhancement by ~2400 times. For a bias current of 7.245 mA, where the effective quality factor of the device and consequently the sensitivity is maximum (2.107 mV nT −1 ), the noise floor is measured to be as low as 2.8 pT (√Hz) −1 . This is by far the most sensitive Lorentz force MEMS magnetometer demonstrated to date.