Ultra-Low Power Corrosion Sensor Made of Iron Nanowires on Magnetic Tunnel Junctions

Abstract
Corrosion sensors are of critical importance for monitoring the destructive potential of a corrosive environment. Due to their large surface-to-volume area, nanowires react with a remarkably high speed, rendering them attractive corrosion-sensing elements. To avoid the difficulties related to contacting nanowires, the authors present a magnetic approach, exploiting the fast reaction of nanowires to the environment. Iron nanowires have a high magnetization value, which decreases upon nanowire corrosion. Due to shape anisotropy, they also possess a large remnant magnetization, which is detectable by a magnetic tunnel junction sensor. Iron nanowires are fabricated by electrochemical deposition, placed on top of the magnetic tunnel junction and aligned using a magnetic field. The nanowires provide a bias field causing a change of the characteristic curve of the tunnel junction. The corrosion sensor is tested in a saline solution, where the nanowires corroded, leading to a reduction of the bias field and restoration of the original characteristic. Combined, the nanowires and tunnel junction realize a highly integrated sensor concept that enables corrosion sensing with an ultra-low power consumption of less than 1 nW, a sensitivity of 0.1%/min, a response time of 30 min and a sensor area of only 128 μm2.

Citation
Mashraei Y, Amara S, Albu Z, Ivanov YP, Kosel J (2018) Ultra-Low Power Corrosion Sensor Made of Iron Nanowires on Magnetic Tunnel Junctions. Advanced Engineering Materials: 1800337. Available: http://dx.doi.org/10.1002/adem.201800337.

Acknowledgements
Y. M. and S. A. made equal contribution to the work. Research reported in this publication was supported by the King Abdullah University of Science and Technology (KAUST). The authors also thank the KAUST Nanofabrication, imaging, and characterization core laboratory staff at KAUST.

Publisher
Wiley

Journal
Advanced Engineering Materials

DOI
10.1002/adem.201800337

Additional Links
https://onlinelibrary.wiley.com/doi/full/10.1002/adem.201800337

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