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Sensors 2018, 18(3), 790;

Hybrid GMR Sensor Detecting 950 pT/sqrt(Hz) at 1 Hz and Room Temperature

Picosense Inc., Berkeley, CA 94704, USA
INESC Microsystems and Nanotechnologies and IN-Institute of Nanoscience and Nanotechnology, 1000-029 Lisbon, Portugal
Instituto Superior Tecnico, Universidade de Lisboa, Av. Rovisco Pais, 1000 Lisbon, Portugal
Berkeley Sensor and Actuator Center, University of California, Davis, CA 95616, USA
Author to whom correspondence should be addressed.
Received: 10 October 2017 / Revised: 24 February 2018 / Accepted: 26 February 2018 / Published: 6 March 2018
(This article belongs to the Special Issue GMR and TMR Sensors)
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Advances in the magnetic sensing technology have been driven by the increasing demand for the capability of measuring ultrasensitive magnetic fields. Among other emerging applications, the detection of magnetic fields in the picotesla range is crucial for biomedical applications. In this work Picosense reports a millimeter-scale, low-power hybrid magnetoresistive-piezoelectric magnetometer with subnanotesla sensitivity at low frequency. Through an innovative noise-cancelation mechanism, the 1/f noise in the MR sensors is surpassed by the mechanical modulation of the external magnetic fields in the high frequency regime. A modulation efficiency of 13% was obtained enabling a final device’s sensitivity of ~950 pT/Hz1/2 at 1 Hz. This hybrid device proved to be capable of measuring biomagnetic signals generated in the heart in an unshielded environment. This result paves the way for the development of a portable, contactless, low-cost and low-power magnetocardiography device. View Full-Text
Keywords: GMR; MEMS; picotesla; low frequency; heart rate GMR; MEMS; picotesla; low frequency; heart rate

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Guedes, A.; Macedo, R.; Jaramillo, G.; Cardoso, S.; Freitas, P.P.; Horsley, D.A. Hybrid GMR Sensor Detecting 950 pT/sqrt(Hz) at 1 Hz and Room Temperature. Sensors 2018, 18, 790.

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