Low Noise, Strain Modulated, Multiferroic Magnetic Field Sensor Systems
Yujia Huo, Sydney Sofronici, Xuan Wang, Michael D’Agati, Peter Finkel, K. Bussmann, Thomas Mion, Margo Staruch, Nicholas J. Jones, Brad Wheeler, Keith McLaughlin, Mark G. Allen, Roy H. Olsson
Abstract
Low noise sensors with low power consumption are needed for sensing the biomagnetic potentials produced by the human body. Compared to their electrical counterparts, biomagnetic sensors are noninvasive and noncontact. A strain-modulated FeCo-Hf/AlScN-based sensor with a bandwidth of 3.4 kHz and a magnetic noise spectral density at 1 kHz of 59.5 pT/ <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\surd $ </tex-math></inline-formula> Hz before demodulation and 98.5 pT/ <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\surd $ </tex-math></inline-formula> Hz after demodulation in an unshielded environment is presented. The footprint of the sensor including flux concentrators is 0.125 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , and the total power consumption of the printed circuit board (PCB)-based readout electronics is 440 mW. A theoretical analysis for the scaling of the sensitivity and the noise spectral density of modulated multiferroic sensor systems is presented.