Journal of Sensors / 2009 / Article / Tab 1

Review Article

Plastic Optical Fibre Sensors for Structural Health Monitoring: A Review of Recent Progress

Table 1

Sensor performance and other comparison criteria.

POF sensing technologyType of POF usedSensor typeStrain resolutionDynamic rangeRelative sensor costRelative equipment costKey features & remarks

Intensiometric
[3, 4, 7, 911, 14, 28, 34]SI MMFIntrinsic 50  1.2%Very low ( US$1/m)Very low (<US$200)Simple design; high cost-effectiveness; demonstrated for flexural and axial loading, crack detection in concrete; monitoring low-velocity impact in advanced composites; POF embedded in fibre composites for axial strain measurement; capable of monitoring quasistatic and dynamic loading ( 30 Hz or higher).

[1215, 35, 36] SI MMF Extrinsic 5  (liquid-filled type); 0.12% Very low ( US$1/m) Very low (<US$200)Simple design; high cost-effectiveness; though strain limit demonstrated up to 40%, higher strains possible; demonstrated for crack detection, monitoring crack-width opening, impact damage, geotextile strain, capable of monitoring quasistatic and dynamic loading ( 1 kHz or higher).
100     (air-filled type) 40% or more

OTDR-based
[3739]SI MMFIntrinsic 0.5% 50%–100%Very low ( US$1/m)Very high (>US$50,000)Distributed measurement; High strain measurement, however, POF axial strain elastic limit 5%; general ability to discriminate loading types based on backscatter shape trace; quasistatic measurement only. Demonstrated to be capable of supporting 100% strain applied at 5 locations along a 100 m POF.
Spatial resolution: 2 m for 50 m POF to 5 m for 100 m POF

[32, 33, 40, 41, 44]SI & GI MMFIntrinsic 0.1% (SI POF) 40%Very low ( US$1/m)Very high ( US$50,000)Distributed measurement of 100 m (SI POF) and 500 m (GI POF); high strain measurement; demonstrated for monitoring geotextile strain, geotextile-retrofitted masonry structures; generally only quasistatic measurement only or very low frequency oscillation ( 0.25 Hz) if high-speed OTDR unit used.
2% (GI POF)
Spatial resolution: 0.1–1 m for 100 m (GI POF)
Interferometric
[30, 31]SM POFIntrinsic0.05  (for gauge length of 0.1 m)15.8%High ( USD$50/m)High ( USD$6000–USD$7000)Large strain measuring capability; High measurement precision; less intrusive due to smaller fibre diameter; Difficulty in cleaving and coupling the single mode fibres in the field; strain rate of 3% strain/min possible.
[43]SI MMFIntrinsic10  500  Very low ( US$1/m)Low ( US$1000)Simple concept; demonstrated dynamic monitoring on a rotor blade up to 5 Hz.

Grating-based
[17, 45, 46] PMMA; SM POFIntrinsic 1  3.6%Currently not commercially available. Estimated cost: High ( US$100)High to very high US$10,000–US$30,000 for OSA-based interrogators and broadband light sourceBragg gratings inscribed on in-house made dye-doped PMMA perform with UV-beam; strain measurement conducted by means of simple tension of POF. Scheme proposed allow temperature and strain to be measured simultaneously; depending on interrogator used, the sensor could monitor quasistatic and dynamic loading conditions.

[2025]mPOFIntrinsic 1  8%Currently not commercially available. Estimated cost: High >US$100High to very high US$10,000–US$30,000 for OSA-based interrogators and broadband light sourceLong period grating mechanically imprinted onto microstructured POF; linear response limited to 2% strain; creeping observed beyond 3%; viscoelastic effects noted above 2% but minimal below 2%; significant material relaxation under constant strain.

[44]SI MMF; GI MMG;IntrinsicNot reportedNot reportedCurrently not commercially available.High to very high US$10,000–US$50,000 for spectrometer, OTDR and broadband light sourceGrating photo-induced onto tapered 0.2 mm SI-MMF and non-tapered GI POF with UV beam; OTDR used as signal interrogator instead of conventional OSA.
mPOFIntrinsicNot reported estimated: 0.02% 1% for initial testEstimated cost: High US$100Long period grating on mPOF integrated to geotextile; length of sensor extended using silica fibres.

Article of the Year Award: Outstanding research contributions of 2020, as selected by our Chief Editors. Read the winning articles.