A simple noncontact force sensor based on an optical fiber Bragg grating attached to a small magnet has been proposed and built. The sensor measures the force between the magnet and any ferromagnetic material placed within a few millimeters of the sensor. Maintaining the sensor at a constant standoff distance, material loss due to corrosion increases the distance between the magnet and the corroded surface, which decreases the magnetic force. This will decrease the strain in the optical fiber shifting the reflected Bragg wavelength. The measured shift for the optical fiber used was 1.36 nm per Newton. Models were developed to optimize the magnet geometry for a specific sensor standoff distance and for particular corrosion pit depths. The sensor was able to detect corrosion pits on a fuel storage tank bottom with depths in the sub-millimeter range.
Rao, Y.; Webb, D.J.; Jackson, D.A.; Zhang, L.; Bennion, I. In-fiber bragg-grating temperature sensor system for medical applications. J. Light. Technol. 1997, 15, 779–785.
[3]
David, N.A.; Wild, P.M.; Djilali, N. Parametric study of a polymer-coated fibre-optic humidity sensor. Meas. Sci. Technol. 2012, 23, doi:10.1088/0957-0233/23/3/035103.
[4]
Liu, L.; Zhang, H.; Zhao, Q.; Liu, Y.; Li, F. Temperature-independent FBG pressure sensor with high sensitivity. Opt. Fiber Technol. 2007, 13, 78–80.
[5]
Gangopadhyay, T.K. Prospects for fibre Bragg gratings and Fabry-Perot interferometers in fibre-optic vibration sensing. Sens. Actuators A 2004, 113, 20–38.
[6]
Carvalho, H.R.; Bruno, A.C.; Braga, A.M.; Valente, L.C.G.; Triques, A.L.C.; Caspary, M.C. Remote magnetostrictive position sensors interrogated by fiber gratings. Sens. Actuators A 2007, 135, 141–145.
[7]
Mora, J.; Martínez-León, L.; Díez, A.; Cruz, J.L. Simultaneous temperature and ac-current measurements for high voltage lines using fiber Bragg gratings. Sens. Actuators A 2006, 125, 311–316.
[8]
Pacheco, J.; Bruno, A.C. The effect of shape anisotropy in giant magnetostrictive fiber Bragg grating sensors. Meas. Sci. Technol. 2010, 21, doi:10.1088/0957-0233/21/6/065205.
Smith, G.N.; Allsop, T.; Kalli, K.; Koutsides, C.; Neal, R.; Sugden, K.; Culverhouse, P.; Bennion, I. Characterisation and performance of a Terfenol-D coated femtosecond laser inscribed optical fibre Bragg sensor with a laser ablated microslot for the detection of static magnetic fields. Opt. Express 2010, 19, 363–370.
Guo, T.; Zhao, Q.; Zhang, H.; Xue, L.; Li, G.; Dong, B.; Liu, B.; Zhang, W.; Kai, G.; Dong, X. Temperature-insensitive fiber Bragg grating force sensor via a bandwidth modulation and optical-power detection technique. J. Light. Technol. 2006, 24, 3797–3802.
[13]
Zhou, W.; Zhao, C.-L.; Dong, X.; Zhang, S.; Chan, C.C.; Shum, P. Simultaneous measurement of force and temperature based on a half corroded FBG. Microw. Opt. Technol. Lett. 2010, 52, 2020–2023.
[14]
Polygerinos, P.; Seneviratne, L.D.; Razavi, R.; Schaeffter, T.; Althoefer, K. Triaxial catheter-tip force sensor for MRI-guided cardiac procedures. IEEE/ASME Trans. Mechatron. 2013, 18, 386–396.
[15]
Park, Y.-L.; Elayaperumal, S.; Daniel, B.; Ryu, S.C.; Shin, M.; Savall, J.; Black, R.J.; Moslehi, B.; Cutkosky, M.R. Real-time estimation of 3-D needle shape and deflection for MRI-guided interventions. IEEE/ASME Trans. Mechatron. 2010, 15, 906–915.
[16]
Monfaredi, R.; Seifabadi, R.; Fichtinger, G.; Iordachita, I. Design of a decoupled MRI-compatible force sensor using fiber Bragg grating sensors for robot-assisted prostate interventions. Proc. SPIE 2013, 8671, doi:10.1117/12.2008160.
[17]
Merzbachery, C.I.; Kersey, A.D.; Friebele, E.J. Fiber optic sensors in concrete structures: A review. Smart Mater. Struct. 1996, 5, 196–208.
[18]
Hassan, M.R.A.; Bakar, M.H.A.; Dambul, K.; Adikan, F.R.M. Optical-based sensors for monitoring corrosion of reinforcement rebar via an etched cladding Bragg grating. Sensors 2012, 12, 15820–15826.
[19]
Zhou, Z.; He, J.; Ou, J. Fiber Optic Sensors; Yasin, M., Ed.; InTech: Rijeka, Croatia, 2012. Chapter 4; p. 77.
[20]
Kermani, M.B.; Harrop, D. The impact of corrosion on oil and gas industry. SPE Prod. Facil. 1996, 11, 186–190.
[21]
Kashyap, R. Fiber Bragg Gratings; Academic Press: Burlington, MA, USA, 2010; p. 189.
[22]
Wieduwilt, T.; Bruckner, S.; Bartelt, H. High force measurement sensitivity with fiber Bragg gratings fabricated in uniform-waist fiber tapers. Meas. Sci. Technol. 2011, 22, doi:10.1088/0957-0233/22/7/075201.
[23]
Brauer, J.R. Magnetic Actuators and Sensors; IEEE Press: Piscataway, NJ, USA, 2006; p. 51.
[24]
Zheng, G.; Pardavi-Horvath, M.; Huang, X. Experimental determination of an effective demagnetization factor for nonellipsoidal geometries. J. Appl. Phys. 1996, 79, 5742–5744.
[25]
Hatch, G.P.; Stelter, R.E. Magnetic design considerations for devices and particles used for biological high-gradient magnetic separation (HGMS). J. Magn. Mag. Mater. 2001, 225, 262–267.
