An Ultra-sensitive Spintronic Strain-gauge Sensor and a Spin-MEMS Microphone

Abstract

This review provides the spintronic strain-gauge sensor (Spin-SGS) based on a magnetic tunnel junction (MTJ) with a high gauge factor in excess of 5000, which was realized by adopting a novel amorphous Fe-B-based sensing layer with high magnetostriction and low coercivity in a high magnetoresistance Mg-O barrier MTJ. This review also provides a demonstration of novel “Spintronic MEMS (Spin-MEMS) microphone,” in which a series of Spin-SGSs are integrated onto a bulk micromachined diaphragm. The Spin-MEMS microphone exhibits a signal-to-noise ratio (SNR) of 57 dB(A) due to the high strain sensitivity of the Spin-SGSs.