{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,27]],"date-time":"2026-02-27T17:14:27Z","timestamp":1772212467125,"version":"3.50.1"},"reference-count":26,"publisher":"MDPI AG","issue":"2","license":[{"start":{"date-parts":[[2020,1,7]],"date-time":"2020-01-07T00:00:00Z","timestamp":1578355200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100002322","name":"Coordena\u00e7\u00e3o de Aperfei\u00e7oamento de Pessoal de N\u00edvel Superior","doi-asserted-by":"publisher","award":["88887.095626\/2015-01"],"award-info":[{"award-number":["88887.095626\/2015-01"]}],"id":[{"id":"10.13039\/501100002322","id-type":"DOI","asserted-by":"publisher"}]},{"name":"Funda\u00e7\u00e3o Estadual de Amparo \u00e0 Pesquisa do Estado do Esp\u00edrito Santo","award":["80605893"],"award-info":[{"award-number":["80605893"]}]},{"name":"Funda\u00e7\u00e3o Estadual de Amparo \u00e0 Pesquisa do Estado do Esp\u00edrito Santo","award":["85426300"],"award-info":[{"award-number":["85426300"]}]},{"name":"Funda\u00e7\u00e3o Estadual de Amparo \u00e0 Pesquisa do Estado do Esp\u00edrito Santo","award":["84336650"],"award-info":[{"award-number":["84336650"]}]},{"DOI":"10.13039\/501100003593","name":"Conselho Nacional de Desenvolvimento Cient\u00edfico e Tecnol\u00f3gico","doi-asserted-by":"publisher","award":["304192\/2016-3"],"award-info":[{"award-number":["304192\/2016-3"]}],"id":[{"id":"10.13039\/501100003593","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100004225","name":"Petrobras","doi-asserted-by":"publisher","award":["2017\/00702-6"],"award-info":[{"award-number":["2017\/00702-6"]}],"id":[{"id":"10.13039\/501100004225","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001871","name":"Funda\u00e7\u00e3o para a Ci\u00eancia e a Tecnologia","doi-asserted-by":"publisher","award":["UID\/CTM\/50025\/2019"],"award-info":[{"award-number":["UID\/CTM\/50025\/2019"]}],"id":[{"id":"10.13039\/501100001871","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>This paper presents the analysis of an intensity variation polymer optical fiber (POF)-based angle sensor performance, i.e., sensitivity, hysteresis and determination coefficient (    R 2    ), using cyclic transparent optical polymer (CYTOP) fiber. The analysis consisted of two approaches: influence of different light source central wavelengths (430 nm, 530 nm, 660 nm, 870 nm and 950 nm) and influence of different angular velocities (    0.70     rad\/s,     0.87     rad\/s,     1.16     rad\/s,     1.75     rad\/s and     3.49     rad\/s). The first approach aimed to select the source which resulted in the most suitable performance regarding highest sensitivity and linearity while maintaining lowest hysteresis, through the figure of merit. Thereafter, the analysis of different angular velocities was performed to evaluate the influence of velocity in the curvature sensor performance. Then, a discrete angular velocity compensation was proposed in order to reduce the root-mean-square error (RMSE) of responses for different angular velocities. Ten tests for each analysis were performed with angular range of     0 \u2218     to     50 \u2218    , based on knee and ankle angle range during the gait. The curvature sensor was applied in patterns simulating the knee and ankle during the gait. Results show repeatability and the best sensor performance for     \u03bb = 950     nm in the first analysis and show high errors for high angular velocities (    w = 3.49     rad\/s) in the second analysis, which presented up to     50 %     angular error. The uncompensated RMSE was high for all velocities (     6.45 \u2218      to      12.41 \u2218     ), whereas the compensated RMSE decreased up to     74 %     (     1.67 \u2218      to      3.62 \u2218     ). The compensated responses of application tests showed maximum error of      5.52 \u2218      and minimum of      1.06 \u2218     , presenting a decrease of mean angular error up to     30 \u2218     when compared with uncompensated responses.<\/jats:p>","DOI":"10.3390\/s20020326","type":"journal-article","created":{"date-parts":[[2020,1,8]],"date-time":"2020-01-08T03:59:57Z","timestamp":1578455997000},"page":"326","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":9,"title":["Performance Analysis of a Lower Limb Multi Joint Angle Sensor Using CYTOP Fiber: Influence of Light Source Wavelength and Angular Velocity Compensation"],"prefix":"10.3390","volume":"20","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-1425-6395","authenticated-orcid":false,"given":"Let\u00edcia","family":"Avellar","sequence":"first","affiliation":[{"name":"Graduate Program in Electrical Engineering, Federal University of Espirito Santo, 29075-910 Vitoria, Brazil"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9075-0619","authenticated-orcid":false,"given":"Arnaldo","family":"Leal-Junior","sequence":"additional","affiliation":[{"name":"Mechanical Engineering Department, Federal University of Espirito Santo, 29075-910 Espirito Santo, Brazil"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8596-5092","authenticated-orcid":false,"given":"Carlos","family":"Marques","sequence":"additional","affiliation":[{"name":"I3N &amp; Physics Department, University of Aveiro, Campus Universit\u00e1rio de Santiago, 3810-193 Aveiro, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0687-3967","authenticated-orcid":false,"given":"Anselmo","family":"Frizera","sequence":"additional","affiliation":[{"name":"Graduate Program in Electrical Engineering, Federal University of Espirito Santo, 29075-910 Vitoria, Brazil"}]}],"member":"1968","published-online":{"date-parts":[[2020,1,7]]},"reference":[{"key":"ref_1","unstructured":"Knudson, D. (2007). Fundamentals of Biomechanics, Springer. [2nd ed.]."},{"key":"ref_2","first-page":"2747","article-title":"Wearable Sensing for Solid Biomechanics: A Review","volume":"15","author":"Wong","year":"2015","journal-title":"IEEE Sens. J."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"1073","DOI":"10.3390\/s140101073","article-title":"A Wireless Flexible Sensorized Insole for Gait Analysis","volume":"14","author":"Crea","year":"2014","journal-title":"Sensors"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"3362","DOI":"10.3390\/s140203362","article-title":"Gait analysis methods: An overview of wearable and non-wearable systems, highlighting clinical applications","volume":"14","year":"2014","journal-title":"Sensors"},{"key":"ref_5","unstructured":"Webster, J.G. (2015). Human Gait and Clinical Movement Analysis. Wiley Encyclopedia of Electrical and Electronics Engineering, John Wiley & Sons Ltd.. Number 37."},{"key":"ref_6","doi-asserted-by":"crossref","unstructured":"M\u00fcller, B., Ilg, W., Giese, M.A., and Ludolph, N. (2017). Validation of enhanced kinect sensor based motion capturing for gait assessment. PLoS ONE, 12.","DOI":"10.1101\/098863"},{"key":"ref_7","doi-asserted-by":"crossref","unstructured":"Leal-Junior, A.G., Frizera-Neto, A., Pontes, M.J., and Botelho, T.R. (2017). Hysteresis compensation technique applied to polymer optical fiber curvature sensor for lower limb exoskeletons. Meas. Sci. Technol., 28.","DOI":"10.1088\/1361-6501\/aa946f"},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"013002","DOI":"10.1088\/0964-1726\/20\/1\/013002","article-title":"Polymer optical fiber sensors\u2014A review","volume":"10","author":"Peters","year":"2011","journal-title":"Smart Mater. Struct."},{"key":"ref_9","doi-asserted-by":"crossref","unstructured":"Leal-junior, A., Theodosiou, A., D\u00edaz, C., Marques, C., Pontes, M.J., Kalli, K., and Frizera-Neto, A. (2018). Fiber Bragg Gratings in CYTOP Fiber Embedded in a 3D-printed Flexible Support for Human-Robot Interaction Forces Assessment. Materials, 11.","DOI":"10.3390\/ma11112305"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"3424","DOI":"10.1109\/JSEN.2012.2212883","article-title":"Wearable Low-Cost System for Human Joint Movements Monitoring Based on Fiber-Optic Curvature Sensor","volume":"12","author":"Stupar","year":"2012","journal-title":"IEEE Sens. J."},{"key":"ref_11","doi-asserted-by":"crossref","unstructured":"Leal-Junior, A.G., Diaz, C.A., Avellar, L.M., Pontes, M.J., Marques, C., and Frizera, A. (2019). Polymer optical fiber sensors in healthcare applications: A comprehensive review. Sensors, 19.","DOI":"10.3390\/s19143156"},{"key":"ref_12","doi-asserted-by":"crossref","unstructured":"Guo, J., Yang, C., Dai, Q., and Kong, L. (2019). Soft and stretchable polymeric optical waveguide-based sensors for wearable and biomedical applications. Sensors, 19.","DOI":"10.3390\/s19173771"},{"key":"ref_13","doi-asserted-by":"crossref","unstructured":"Costa, J.C., Spina, F., Lugoda, P., Garcia-garcia, L., Roggen, D., and M\u00fcnzenrieder, N. (2019). Flexible Sensors\u2014From Materials to Applications. Technologies, 7.","DOI":"10.3390\/technologies7020035"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"7085","DOI":"10.1109\/JSEN.2018.2852363","article-title":"Polymer Optical Fiber Sensors in Wearable Devices: Toward Novel Instrumentation Approaches for Gait Assistance Devices","volume":"18","author":"Frizera","year":"2018","journal-title":"IEEE Sens. J."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"045801","DOI":"10.1088\/0957-0233\/22\/4\/045801","article-title":"A reliable low-cost wireless and wearable gait monitoring system based on a plastic optical fibre sensor","volume":"22","author":"Bilro","year":"2011","journal-title":"Meas. Sci. Technol."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"387","DOI":"10.1109\/LPT.2013.2294878","article-title":"Distributed Temperature Sensing in Polymer Optical Fiber by BOFDA","volume":"26","author":"Minardo","year":"2014","journal-title":"IEEE Photonics Technol. Lett."},{"key":"ref_17","doi-asserted-by":"crossref","unstructured":"Luo, Y., Yan, B., Zhang, Q., Peng, G.-D., and Wen, J. (2017). Fabrication of Polymer Optical Fibre (POF) Gratings. Sensors, 17.","DOI":"10.3390\/s17030511"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"2654","DOI":"10.1109\/JLT.2017.2696301","article-title":"Stress Sensitivity Analysis of Optical Fiber Bragg erot Interferometric Sensors","volume":"35","author":"Pospori","year":"2017","journal-title":"J. Light. Technol."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"30051","DOI":"10.1364\/OE.25.030051","article-title":"Polymethyl methacrylate (PMMA) recycling for the production of optical fiber sensor systems","volume":"25","author":"Prado","year":"2017","journal-title":"Opt. Express"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"22","DOI":"10.1038\/asiamat.2009.2","article-title":"The future of plastic optical fiber","volume":"1","author":"Koike","year":"2009","journal-title":"NPG Asia Mater."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"4799","DOI":"10.1364\/OL.43.004799","article-title":"Characterization of a new polymer optical fiber with enhanced sensing capabilities using a Bragg grating","volume":"43","author":"Theodosiou","year":"2018","journal-title":"Opt. Lett."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"2539","DOI":"10.1364\/OL.43.002539","article-title":"Design and characterization of a curvature sensor using fused polymer optical fibers","volume":"43","author":"Frizera","year":"2018","journal-title":"Opt. Lett."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"1112","DOI":"10.1109\/JLT.2017.2752361","article-title":"Dynamic Compensation Technique for POF Curvature Sensors","volume":"36","author":"Frizera","year":"2018","journal-title":"J. Light. Technol."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"35","DOI":"10.1016\/j.optlastec.2018.02.035","article-title":"Viscoelastic features based compensation technique for polymer optical fiber curvature sensors","volume":"105","author":"Frizera","year":"2018","journal-title":"Opt. Laser Technol."},{"key":"ref_25","unstructured":"Industrial Fiber Optics (2006). Plastic Fiber Optic Phototransistor IF-D92, Industrial Fiber Optics."},{"key":"ref_26","unstructured":"Kirtley, C. (2006). Clinical Gait Analysis: Theory and Practice, Elsevier B.V.. [1st ed.]."}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/20\/2\/326\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,13]],"date-time":"2025-10-13T14:03:44Z","timestamp":1760364224000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/20\/2\/326"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2020,1,7]]},"references-count":26,"journal-issue":{"issue":"2","published-online":{"date-parts":[[2020,1]]}},"alternative-id":["s20020326"],"URL":"https:\/\/doi.org\/10.3390\/s20020326","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2020,1,7]]}}}