TY - JOUR
T1 - Serial MTJ-based TMR sensors in bridge configuration for detection of fractured steel bar in magnetic flux leakage testing
AU - Jin, Zhenhu
AU - Mohd Noor Sam, Muhamad Arif Ihsan
AU - Oogane, Mikihiko
AU - Ando, Yasuo
N1 - Funding Information:
The work was supported by the S-Innovation program, the Japan Science and Technology Agency (JST, 201106007), the Center for Innovative Integrated Electronic System (CIES), the Center for Spintronics Research Network (CSRN), and the Organization for Advanced Studies, Center for Science and Innovation in Spintronics.
Publisher Copyright:
© 2021 by the authors. Licensee MDPI, Basel, Switzerland.
PY - 2021/1/2
Y1 - 2021/1/2
N2 - Thanks to high sensitivity, excellent scalability, and low power consumption, magnetic tunnel junction (MTJ)-based tunnel magnetoresistance (TMR) sensors have been widely implemented in various industrial fields. In nondestructive magnetic flux leakage testing, the magnetic sensor plays a significant role in the detection results. As highly sensitive sensors, integrated MTJs can suppress frequency-dependent noise and thereby decrease detectivity; therefore, serial MTJ-based sensors allow for the design of high-performance sensors to measure variations in magnetic fields. In the present work, we fabricated serial MTJ-based TMR sensors and connected them to a full Wheatstone bridge circuit. Because noise power can be suppressed by using bridge configuration, the TMR sensor with Wheatstone bridge configuration showed low noise spectral density (0.19 μV/Hz0.5) and excellent detectivity (5.29 × 10−8 Oe/Hz0.5) at a frequency of 1 Hz. Furthermore, in magnetic flux leakage testing, compared with one TMR sensor, the Wheatstone bridge TMR sensors provided a higher signal-to-noise ratio for inspection of a steel bar. The one TMR sensor system could provide a high defect signal due to its high sensitivity at low lift-off (4 cm). However, as a result of its excellent detectivity, the full Wheatstone bridge-based TMR sensor detected the defect even at high lift-off (20 cm). This suggests that the developed TMR sensor provides excellent detectivity, detecting weak field changes in magnetic flux leakage testing.
AB - Thanks to high sensitivity, excellent scalability, and low power consumption, magnetic tunnel junction (MTJ)-based tunnel magnetoresistance (TMR) sensors have been widely implemented in various industrial fields. In nondestructive magnetic flux leakage testing, the magnetic sensor plays a significant role in the detection results. As highly sensitive sensors, integrated MTJs can suppress frequency-dependent noise and thereby decrease detectivity; therefore, serial MTJ-based sensors allow for the design of high-performance sensors to measure variations in magnetic fields. In the present work, we fabricated serial MTJ-based TMR sensors and connected them to a full Wheatstone bridge circuit. Because noise power can be suppressed by using bridge configuration, the TMR sensor with Wheatstone bridge configuration showed low noise spectral density (0.19 μV/Hz0.5) and excellent detectivity (5.29 × 10−8 Oe/Hz0.5) at a frequency of 1 Hz. Furthermore, in magnetic flux leakage testing, compared with one TMR sensor, the Wheatstone bridge TMR sensors provided a higher signal-to-noise ratio for inspection of a steel bar. The one TMR sensor system could provide a high defect signal due to its high sensitivity at low lift-off (4 cm). However, as a result of its excellent detectivity, the full Wheatstone bridge-based TMR sensor detected the defect even at high lift-off (20 cm). This suggests that the developed TMR sensor provides excellent detectivity, detecting weak field changes in magnetic flux leakage testing.
KW - Magnetic flux leakage testing
KW - Magnetic tunnel junctions
KW - Magnetoresistive sensor
KW - Nondestructive testing
KW - Tunnel magnetoresistance sensor
UR - http://www.scopus.com/inward/record.url?scp=85099884807&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85099884807&partnerID=8YFLogxK
U2 - 10.3390/s21020668
DO - 10.3390/s21020668
M3 - Letter
C2 - 33477948
AN - SCOPUS:85099884807
VL - 21
SP - 1
EP - 10
JO - Sensors (Switzerland)
JF - Sensors (Switzerland)
SN - 1424-8220
IS - 2
M1 - 668
ER -