Strain Sensor Based on Embedded Fiber Bragg Grating in Thermoplastic Polyurethane Using the 3D Printing Technology for Improved Sensitivity

Abstract

A new and easy-to-fabricate strain sensor has been developed, based on fiber Bragg grating (FBG) technology embedded into a thermoplastic polyurethane filament using a 3-dimensional (3D) printer. Taking advantage of the flexibility and elastic properties of the thermoplastic polyurethane material, the embedding of the FBG provides durable protection with enhanced flexibility and sensitivity, as compared to the use of a bare FBG. Results of an evaluation of its performance have shown that the FBG sensors embedded in this way can be applied effectively in the measurement of strain, with an average wavelength responsivity of 0.013 5 nm/cm of displacement for tensile strain and −0.014 2 nm/cm for compressive strain, both showing a linearity value of up to 99%. Furthermore, such an embedded FBG-based strain sensor has a sensitivity of ∼1.74 times greater than that of a bare FBG used for strain measurement and is well protected and suitable for in-the-field use. It is also observed that the thermoplastic polyurethane based (TPU-based) FBG strain sensor carries a sensitivity value of ∼2.05 times higher than that of the polylactic acid based (PLA-based) FBG strain sensor proving that TPU material can be made as the material of choice as a “sensing” pad for the FBG.

Keywords

Fiber-optic sensors / fiber Bragg grating / 3D printing technology / multiple-point strain measurement

References

[1] Hong C, Zhang Y, Lu Z, Yin Z. A FBG tilt sensor fabricated using 3D printing technique for monitoring ground movement. IEEE Sensors Journal, 2019, 19(15): 6392-6399.

[2] Diniz J L C, Vieira R D, Castro J T, Benjamin A C, Freire J L F. Stress and strain analysis of pipelines with localized metal loss. Experimental Mechanics, 2006, 46(6): 765-775.

[3] H. Xu, F. Li, W. Zhao, S. Wang, Y. Du, and C. Bian, “A high precision fiber Bragg grating inclination sensor for slope monitoring,” Journal of Sensors, 2019, DOI: https://doi.org/10.1155/2019/1354029.

[4] Zhu H H, Ho A N L, Yin J H, Sun H W, Pei H F, Hong C Y. An optical fibre monitoring system for evaluating the performance of a soil nailed slope. Smart Structures and Systems, 2012, 9(5): 393-410.

[5] Corominas J, Moya J, Lloret A. Measurement of landslide displacements using a wire extensometer. Engineering Geology, 2000, 55(3): 149-166.

[6] Fang L, Chen T, Li R, Liu S. Application of embedded fiber Bragg grating (FBG) sensors in monitoring health to 3D printing structures. IEEE Sensors Journal, 2016, 16(17): 6604-6610.

[7] Hong C Y, Zhang Y F, Zhang M X, Leung L M G, Liu L Q. Application of FBG sensors for geotechnical health monitoring, a review of sensor design, implementation methods and packaging techniques. Sensors and Actuators A: Physical, 2016, 244, 184-197.

[8] Zhao Y, Ansari F. Quasi-distributed fiber-optic strain sensor: principle and experiment. Applied Optics, 2001, 40(19): 3176-3181.

[9] Wang Q, Huang J, Liu Q, Zhou Z. Dynamic strain measurement of hydraulic system pipeline using fibre Bragg grating sensors. Advances in Mechanical Engineering, 2016, 8(4): 1687814016645069.

[10] Maheshwari M, Yang Y, Upadrashta D, Huang E S, Goh K H. Fiber Bragg grating (FBG) based magnetic extensometer for ground settlement monitoring. Sensors and Actuators A: Physical, 2019, 296, 132-144.

[11] Campanella C E, Cuccovillo A, Campanella C, Yurt A, Passaro V M N. Fibre Bragg Grating based strain sensors: review of technology and applications. Sensors, 2018, 18(9): 3115.

[12] Emmons M C, Karnani S, Trono S, Mohanchandra K P, Richards W L, Carman G P. Strain measurement validation of embedded fiber Bragg gratings. International Journal of Optomechatronics, 2010, 4(1): 22-33.

[13] Park S W, Kang D H, Bang H J, Park S O, Kim C G. Strain monitoring and damage detection of a filament wound composite pressure tank using embedded fiber Bragg grating sensors. Key Engineering Materials, 2006, 321–323(10): 182-185.

[14] Ismail D S B A, Kassim A, Mohamad H B, Rashid A S A, Bunawan A R. Monitoring strain development of soil slope using distributed optical fibre sensor. IOP Conference Series: Materials Science and Engineering, 2019, 527(1): 012027.

[15] N. Tanaka, Y. Okabe, and N. Takeda, “Temperature-compensated strain measurements using FBG sensors embedded in composite laminates,” in SPIE’s 9th Annual International Symposium on Smart Structures and Materials, San Diego, 2002, pp. 304–313.

[16] Chen Y C, Hsieh C C, Lin C C. Strain measurement for composite tubes using embedded, fiber Bragg grating sensor. Sensors and Actuators A: Physical, 2011, 167(1): 63-69.

[17] Zubel M G, Sugden K, Webb D J, Sáez-Rodríguez D, Nielsen K, Bang O. Embedding silica and polymer fibre Bragg gratings (FBG) in plastic 3D-printed sensing patches. SPIE, 2016, 9886, 1-12.

[18] Leal-Junior A G, Marques C, Ribeiro M R N, Pontes M J, Frizera A. FBG-embedded 3-D printed ABS sensing pads: the impact of infill density on sensitivity and dynamic range in force sensors. IEEE Sensors Journal, 2018, 18(20): 8381-8388.

[19] Hong C, Zhang Y, Borana L. Design, fabrication and testing of a 3D printed FBG pressure sensor. IEEE Access, 2019, 7(10): 38577-38583.

[20] Liacouras P C, Grant G T, Choudhry K, Strouse G F, Ahmed Z. Fiber Bragg gratings embedded in 3D-printed scaffolds. NCSLI Measure, 2015, 10(2): 50-52.

[21] Jiang S F, Qiao Z H, Li N L, Luo J B, Shen S, Hu W H, . Structural health monitoring system based on FBG sensing technique for Chinese ancient timber buildings. Sensors, 2020, 20(1): 1-17.

[22] Sanada H, Sugita Y, Kashiwai Y. Development of a multi-interval displacement sensor using fiber Bragg grating technology. International Journal of Rock Mechanics and Mining Sciences, 2012, 54, 27-36.

[23] Lee J, Kim Y, Lee J H. A 3-D-printed, temperature sensor based on mechanically-induced long period fibre gratings. Journal of Modern Optics, 2020, 67(5): 469-474.

[24] Liveira R, Nogueira R, Bilro L. 3D printed long period gratings and their applications as high sensitivity shear-strain and torsion sensors. Optics Express, 2021, 29(12): 17795-17814.

[25] M. Alsharari, B. Chen, and W. Shu, “3D-printing of highly stretchable and sensitive strain sensors using graphene based composites,” in Eurosensors 2018 Conference, Austria, September 9–12, 2018, pp. 8–11.

[26] Tian H, Liu D, Wang Y, Wang Q. Effect of adhesive type on the sensitivity coefficient of FBG sensor bonded on the surface of CFRP. Optoelectronics Letters, 2019, 15(4): 264-268.

[27] Wang Y L, Shi B, Zhang T L, Zhu H H, Jie Q, Sun Q. Introduction to an FBG-based inclinometer and its application to landslide monitoring. Journal of Civil Structural Health Monitoring, 2015, 5(5): 645-653.

[28] Pei H F, Yin J H, Zhu H H, Hong C Y, Jin W, Xu D S. Monitoring of lateral displacements of a slope using a series of special fibre Bragg grating-based in-place inclinometers. Measurement Science and Technology, 2012, 23(2): 025007.

[29] Pei H, Yin J, Jin W. Development of novel optical fiber sensors for measuring tilts and displacements of geotechnical structures. Measurement Science and Technology, 2013, 24(9): 095202.

[30] Lee H, Eom R, Lee Y. Evaluation of the mechanical properties of porous thermoplastic polyurethane obtained by 3D printing for protective gear. Advances in Materials Science and Engineering, 2019, 2019, 5838361.

[31] Pinto V C, Ramos T, Alves S, Xavier J, Tavares P, Moreir P M G P, . Comparative failure analysis of PLA, PLA/GNP and PLA/CNT-COOH biodegradable nanocomposites thin films. Procedia Engineering, 2015, 114, 635-642.