Low-frequency voltage mode sensing of magnetoelectric sensor in package

An in-package voltage-sensing integrated magnetometer for low frequency neural recording at room temperature is presented. The detection system consists of a voltage mode CMOS amplifier with an active biasing circuit and a Metglas/Polyvinylidene fluoride (PVDF)-based magnetoelectric (ME) unimorph sensor measuring 10 × 3 × 0.025 mm in volume, representing the smallest ME sensor volume reported to date. Over the frequency range of interest (0.5 Hz-1 kHz), both theories and experiments are in excellent agreement and the fabricated magnetometer exhibits a frequency independent signal-to-noise ratio (SNR) at the system level. The magnetometer achieves a SNR of 3000 and detects a minimum detectable field of 30 nano-Tesla waveform. This system in package provides a feasibility demonstration of integration of ME sensors directly with NMOS readout electronics aimed at tiny magnetic field detection for bio-imaging applications.