{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,1,21]],"date-time":"2026-01-21T08:14:00Z","timestamp":1768983240970,"version":"3.49.0"},"reference-count":33,"publisher":"MDPI AG","issue":"11","license":[{"start":{"date-parts":[[2020,6,4]],"date-time":"2020-06-04T00:00:00Z","timestamp":1591228800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001871","name":"Funda\u00e7\u00e3o para a Ci\u00eancia e a Tecnologia","doi-asserted-by":"publisher","award":["UIDB\/50025\/2020"],"award-info":[{"award-number":["UIDB\/50025\/2020"]}],"id":[{"id":"10.13039\/501100001871","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":["UIDP\/50025\/2020"],"award-info":[{"award-number":["UIDP\/50025\/2020"]}],"id":[{"id":"10.13039\/501100001871","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":["CEECIND\/00034\/2018"],"award-info":[{"award-number":["CEECIND\/00034\/2018"]}],"id":[{"id":"10.13039\/501100001871","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100003593","name":"Conselho Nacional de Desenvolvimento Cient\u00edfico e Tecnol\u00f3gico","doi-asserted-by":"publisher","award":["304049\/2019-0"],"award-info":[{"award-number":["304049\/2019-0"]}],"id":[{"id":"10.13039\/501100003593","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100003593","name":"Conselho Nacional de Desenvolvimento Cient\u00edfico e Tecnol\u00f3gico","doi-asserted-by":"publisher","award":["309003\/2018-0"],"award-info":[{"award-number":["309003\/2018-0"]}],"id":[{"id":"10.13039\/501100003593","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100006182","name":"FAPES","doi-asserted-by":"publisher","award":["85426300 and 84336650"],"award-info":[{"award-number":["85426300 and 84336650"]}],"id":[{"id":"10.13039\/501100006182","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Advances in robotic systems for rehabilitation purposes have led to the development of specialized robot-assisted rehabilitation clinics. In addition, advantageous features of polymer optical fiber (POF) sensors such as light weight, multiplexing capabilities, electromagnetic field immunity and flexibility have resulted in the widespread use of POF sensors in many areas. Considering this background, this paper presents an integrated POF intensity variation-based sensor system for the instrumentation of different devices. We consider different scenarios for physical rehabilitation, resembling a clinic for robot-assisted rehabilitation. Thus, a multiplexing technique for POF intensity variation-based sensors was applied in which an orthosis for flexion\/extension movement, a modular exoskeleton for gait assistance and a treadmill were instrumented with POF angle and force sensors, where all the sensors were integrated in the same POF system. In addition, wearable sensors for gait analysis and physiological parameter monitoring were also proposed and applied in gait exercises. The results show the feasibility of the sensors and methods proposed, where, after the characterization of each sensor, the system was implemented with three volunteers: one for the orthosis on the flexion\/extension movements, one for the exoskeleton for gait assistance and the other for the free gait analysis using the proposed wearable POF sensors. To the authors\u2019 best knowledge, this is the first time that optical fiber sensors have been used as a multiplexed and integrated solution for the simultaneous assessment of different robotic devices and rehabilitation protocols, where such an approach results in a compact, fully integrated and low-cost system, which can be readily employed in any clinical environment.<\/jats:p>","DOI":"10.3390\/s20113199","type":"journal-article","created":{"date-parts":[[2020,6,5]],"date-time":"2020-06-05T03:32:21Z","timestamp":1591327941000},"page":"3199","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":23,"title":["Polymer Optical Fiber-Based Integrated Instrumentation in a Robot-Assisted Rehabilitation Smart Environment: A Proof of Concept"],"prefix":"10.3390","volume":"20","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-9075-0619","authenticated-orcid":false,"given":"Arnaldo","family":"Leal-Junior","sequence":"first","affiliation":[{"name":"Graduate Program of Electrical Engineering, Federal University of Espirito Santo, Vit\u00f3ria 29075-910, Brazil"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1425-6395","authenticated-orcid":false,"given":"Leticia","family":"Avellar","sequence":"additional","affiliation":[{"name":"Graduate Program of Electrical Engineering, Federal University of Espirito Santo, Vit\u00f3ria 29075-910, Brazil"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8009-2958","authenticated-orcid":false,"given":"Jonathan","family":"Jaimes","sequence":"additional","affiliation":[{"name":"Department of Mechanical Engineering, Engineering School of S\u00e3o Carlos, University of S\u00e3o Paulo, S\u00e3o Carlos 13566-590, Brazil"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9657-5076","authenticated-orcid":false,"given":"Camilo","family":"D\u00edaz","sequence":"additional","affiliation":[{"name":"Graduate Program of Electrical Engineering, Federal University of Espirito Santo, Vit\u00f3ria 29075-910, Brazil"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6011-9968","authenticated-orcid":false,"given":"Wilian","family":"dos Santos","sequence":"additional","affiliation":[{"name":"Department of Mechanical Engineering, Engineering School of S\u00e3o Carlos, University of S\u00e3o Paulo, S\u00e3o Carlos 13566-590, Brazil"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0663-156X","authenticated-orcid":false,"given":"Adriano A. G.","family":"Siqueira","sequence":"additional","affiliation":[{"name":"Department of Mechanical Engineering, Engineering School of S\u00e3o Carlos, University of S\u00e3o Paulo, S\u00e3o Carlos 13566-590, Brazil"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9009-2425","authenticated-orcid":false,"given":"Maria Jos\u00e9","family":"Pontes","sequence":"additional","affiliation":[{"name":"Graduate Program of Electrical Engineering, Federal University of Espirito Santo, Vit\u00f3ria 29075-910, Brazil"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8596-5092","authenticated-orcid":false,"given":"Carlos","family":"Marques","sequence":"additional","affiliation":[{"name":"I3N &amp; Physics Department, Universidade de 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 of Electrical Engineering, Federal University of Espirito Santo, Vit\u00f3ria 29075-910, Brazil"}]}],"member":"1968","published-online":{"date-parts":[[2020,6,4]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"111","DOI":"10.1177\/1545968307305457","article-title":"Effects of Robot-Assisted Therapy on Upper Limb Recovery After Stroke: A Systematic Review","volume":"22","author":"Kwakkel","year":"2008","journal-title":"Neurorehabil. Neural Repair"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"S290","DOI":"10.1097\/PHM.0b013e31826bcd80","article-title":"Robotic Therapy","volume":"91","author":"Krebs","year":"2012","journal-title":"Am. J. Phys. Med. Rehabil."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"1068","DOI":"10.1109\/JSYST.2014.2351491","article-title":"Lower Limb Wearable Robots for Assistance and Rehabilitation: A State of the Art","volume":"10","author":"Huo","year":"2016","journal-title":"IEEE Syst. J."},{"key":"ref_4","unstructured":"dos Santos, W.M., Caurin, G.A.P., and Siqueira, A.A.G. (2015). Design and control of an active knee orthosis driven by a rotary Series Elastic Actuator. Control Eng. Pract., 1\u201312."},{"key":"ref_5","unstructured":"(2019, May 22). Advanced Physical Therapy and Rehabilitation Center, LLC. Available online: http:\/\/www.aptrehab.com."},{"key":"ref_6","doi-asserted-by":"crossref","unstructured":"Moreno, J.C., Bueno, L., Pons, J.L., Baydal-Bertomeu, J.M., Belda-Lois, J.M., Prat, J.M., and Barber, R. (2008). Wearable Robot Technologies. Wearable Robots, John Wiley & Sons, Ltd.","DOI":"10.1002\/9780470987667.ch6"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"2635","DOI":"10.1109\/TBME.2012.2208750","article-title":"Shoulder and elbow joint angle tracking with inertial sensors","volume":"59","author":"McNames","year":"2012","journal-title":"IEEE Trans. Biomed. Eng."},{"key":"ref_8","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_9","doi-asserted-by":"crossref","first-page":"243","DOI":"10.1080\/14686996.2018.1431862","article-title":"3D printing for soft robotics \u2013 a review","volume":"19","author":"Gul","year":"2018","journal-title":"Sci. Technol. Adv. Mater."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"78","DOI":"10.1038\/s41578-018-0011-1","article-title":"Human-in-the-loop development of soft wearable robots","volume":"3","author":"Walsh","year":"2018","journal-title":"Nat. Rev. Mater."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"99","DOI":"10.1016\/j.procs.2011.12.030","article-title":"Soft robotics: Challenges and perspectives","volume":"7","author":"Iida","year":"2011","journal-title":"Procedia Comput. Sci."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"7394","DOI":"10.3390\/s140407394","article-title":"Fiber Bragg Grating Sensors toward Structural Health Monitoring in Composite Materials: Challenges and Solutions","volume":"14","author":"Kinet","year":"2014","journal-title":"Sensors"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"7179","DOI":"10.1109\/JSEN.2019.2915031","article-title":"Optical Fiber Sensing for Sub-Millimeter Liquid Level Monitoring: A Review","volume":"19","author":"Diaz","year":"2019","journal-title":"IEEE Sens. J."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"279","DOI":"10.1016\/j.sna.2011.02.045","article-title":"Fiber grating sensors in medicine: Current and emerging applications","volume":"167","author":"Mishra","year":"2011","journal-title":"Sensors Actuators A Phys."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"013002","DOI":"10.1088\/0964-1726\/20\/1\/013002","article-title":"Polymer optical fiber sensors\u2014a review","volume":"20","author":"Peters","year":"2011","journal-title":"Smart Mater. Struct."},{"key":"ref_16","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_17","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_18","doi-asserted-by":"crossref","unstructured":"Leal-Junior, A., Theodosiou, A., D\u00edaz, C., Marques, C., Pontes, M., Kalli, K., and Frizera-Neto, A. (2018). Fiber Bragg Gratings in CYTOP Fibers Embedded in a 3D-Printed Flexible Support for Assessment of Human\u2013Robot Interaction Forces. Materials (Basel), 11.","DOI":"10.3390\/ma11112305"},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"2208","DOI":"10.1364\/OME.8.002208","article-title":"Fabry-P\u00e9rot cavities based on photopolymerizable resins for sensing applications","volume":"8","author":"Oliveira","year":"2018","journal-title":"Opt. Mater. Express"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"12184","DOI":"10.3390\/s120912184","article-title":"Optical sensors based on plastic fibers","volume":"12","author":"Bilro","year":"2012","journal-title":"Sensors (Switzerland)"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"125103","DOI":"10.1088\/1361-6501\/aa946f","article-title":"Hysteresis compensation technique applied to polymer optical fiber curvature sensor for lower limb exoskeletons","volume":"28","author":"Pontes","year":"2017","journal-title":"Meas. Sci. Technol."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"205","DOI":"10.1016\/j.yofte.2018.02.001","article-title":"Polymer optical fiber strain gauge for human-robot interaction forces assessment on an active knee orthosis","volume":"41","author":"Frizera","year":"2018","journal-title":"Opt. Fiber Technol."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"256","DOI":"10.1016\/j.optlastec.2019.03.035","article-title":"3D-printed POF insole: Development and applications of a low-cost, highly customizable device for plantar pressure and ground reaction forces monitoring","volume":"116","author":"Marques","year":"2019","journal-title":"Opt. Laser Technol."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"323","DOI":"10.1016\/j.optlastec.2018.11.044","article-title":"Polymer optical fiber-embedded, 3D-printed instrumented support for microclimate and human-robot interaction forces assessment","volume":"112","author":"Pontes","year":"2019","journal-title":"Opt. Laser Technol."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"81","DOI":"10.1016\/j.optlastec.2018.09.044","article-title":"Multiplexing technique for quasi-distributed sensors arrays in polymer optical fiber intensity variation-based sensors","volume":"111","author":"Marques","year":"2019","journal-title":"Opt. Laser Technol."},{"key":"ref_26","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_27","first-page":"759764","article-title":"Lower-Limb Robotic Rehabilitation: Literature Review and Challenges","volume":"2011","author":"Gil","year":"2011","journal-title":"J. Robot."},{"key":"ref_28","first-page":"155","article-title":"Development of Polymer Optical Fiber Sensors for Lower Limb Exoskeletons Instrumentation","volume":"Volume 16","author":"Pons","year":"2019","journal-title":"Wearable Robotics: Challenges and Trends"},{"key":"ref_29","doi-asserted-by":"crossref","unstructured":"Dos Santos, W.M., Nogueira, S.L., De Oliveira, G.C., Pe\u00f1a, G.G., and Siqueira, A.A.G. (2017, January 17\u201320). Design and evaluation of a modular lower limb exoskeleton for rehabilitation. Proceedings of the 2017 International Conference on Rehabilitation Robotics (ICORR), London, UK.","DOI":"10.1109\/ICORR.2017.8009288"},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"272","DOI":"10.1016\/j.optlastec.2017.10.006","article-title":"Sensitive zone parameters and curvature radius evaluation for polymer optical fiber curvature sensors","volume":"100","author":"Frizera","year":"2018","journal-title":"Opt. Laser Technol."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"2362","DOI":"10.1109\/JSEN.2018.2797363","article-title":"Polymer Optical Fiber for In-Shoe Monitoring of Ground Reaction Forces During the Gait","volume":"18","author":"Frizera","year":"2018","journal-title":"IEEE Sens. J."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"429","DOI":"10.1016\/j.optlastec.2018.08.036","article-title":"Polymer optical fiber-based sensor for simultaneous measurement of breath and heart rate under dynamic movements","volume":"109","author":"Pontes","year":"2019","journal-title":"Opt. Laser Technol."},{"key":"ref_33","unstructured":"Kirtley, C. (2006). Clinical Gait Analysis: Theory and Practice, Elsevier."}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/20\/11\/3199\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T09:35:45Z","timestamp":1760175345000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/20\/11\/3199"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2020,6,4]]},"references-count":33,"journal-issue":{"issue":"11","published-online":{"date-parts":[[2020,6]]}},"alternative-id":["s20113199"],"URL":"https:\/\/doi.org\/10.3390\/s20113199","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2020,6,4]]}}}