Magnetocardiography with sensors based on giant magnetoresistance

Pannetier‐Lecœur, M.; Parkkonen, Lauri; Sergeeva-Chollet, N.; Polovy, H.; Fermon, C.; Fowley, C.

doi:10.1063/1.3575591

Cited by 97 publications

(54 citation statements)

References 15 publications

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“…3,4 These applications require magnetic sensors with nanotesta or even lower field detectivity in the low frequency range. Magnetic tunnel junctions (MTJs) with a crystalline MgO barrier seem to be a logical choice for such sensor applications due to their large tunnel magnetoresistance (TMR) ratios.…”

mentioning

confidence: 99%

Yoke-shaped MgO-barrier magnetic tunnel junction sensors

Chen

Carroll

Feng

et al. 2012

Applied Physics Letters

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mentioning

confidence: 99%

Yoke-shaped MgO-barrier magnetic tunnel junction sensors

Chen

Carroll

Feng

et al. 2012

Applied Physics Letters

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“…The first one consists of amplifying the sensed field by flux concentrators. These flux concentrators can be either superconducting [24] with enhancement of gain of more than 1000 allowing subpicotesla detection at 1Hz or femtoTesla detection at high frequencies but at lower temperature, either with soft materials [25] with gain up to 100 at room temperature. A more sophisticated approach consists of using a modulated flux concentrator so that the field seen by the sensor is no more at low frequencies but displaced to higher frequencies where the sensors are in the thermal regime.…”

Section: Discussionmentioning

confidence: 99%

Noise in GMR and TMR Sensors

Fermon

Pannetier‐Lecœur

2013

Giant Magnetoresistance (GMR) Sensors

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Abstract. Giant Magnetoresistances (GMR) and Tunnel Magnetoresistances (TMR) take an increasing part in many applications like current sensing, magnetometry or position sensing, thanks to their high magnetoresistance at room temperature, which leads to a large output signal variation. But the real performances of such sensors can only be estimated with respect to the sources of noise. In this chapter, we give first some bases on noise theory and data treatment. Fluctuations, ergodicity and volume considerations will be discussed. A second part will detail noise measurement techniques and data analysis of typical noise power spectra. Sources of noise will be discussed in a third part. In the end of the chapter, specific cases of GMR and TMR magnetic noise and non magnetic noise will be discussed with their physical origin and their analytical or phenomenological expression. We will then present ways to design GMR and TMR sensors for noise reduction, depending on the applications targeted.

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“…Biomagnetic signatures of the electrical activity of the human heart have been recorded using giant magnetoresistive (GMR) sensors [1]. A self-powered magnetoresistive sensor capable of detecting DC and AC external magnetic fields in the thermal noise regime has been developed [2].…”

Section: Introductionmentioning

confidence: 99%

Novel non-intrusive sensor for piston position measurement

Taghvaeeyan

Rajamani

Sun

2013

2013 American Control Conference

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This paper proposes a novel sensor for the nonintrusive real-time measurement of piston position inside a cylinder. The proposed sensor exploits the principle that any ferromagnetic object has an inherent magnetic field which varies as a function of position around the object. By modeling the magnetic field as a function of position and using sensors to measure magnetic field intensity, the position of the object can be estimated. This principle is used to measure piston position in a free piston engine without requiring any sensors inside the engine cylinder. The piston is approximated as a rectangular metallic object and the variation of the magnetic field around it is modeled. A challenge arises from the fact that the parameters of the model would vary from engine to engine and would be cumbersome to calibrate for each engine. This challenge is addressed by utilizing two magnetic field sensors with known longitudinal separation between them. An iterated least squares algorithm then provides adaptive parameter estimates and accurate position estimation. Experimental results from a free piston engine set up show that the proposed sensor can provide better than 0.4 mm accuracy in position estimates. The proposed sensing concept can be utilized for piston position measurement in multi-cylinder SI and diesel engines, hydraulic cylinders and in many other position measurement applications.

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Magnetocardiography with sensors based on giant magnetoresistance

Cited by 97 publications

References 15 publications

Yoke-shaped MgO-barrier magnetic tunnel junction sensors

Yoke-shaped MgO-barrier magnetic tunnel junction sensors

Noise in GMR and TMR Sensors

Novel non-intrusive sensor for piston position measurement

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