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Bend-Direction and Rotation Plastic Optical Fiber Sensor. SENSORS 2020; 20:s20185405. [PMID: 32967211 PMCID: PMC7570926 DOI: 10.3390/s20185405] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Revised: 09/09/2020] [Accepted: 09/17/2020] [Indexed: 11/16/2022]
Abstract
A plastic filament of poly (methyl methacrylate) (PMMA) was fabricated by extrusion. The mode confinement was simulated using numerical software. The idea is to study how the light intensity changes inside the plastic optical fiber (POF) when a bending in multiple directions is applied. The results obtained from the simulation were compared to the experimental observations. The non-circular shape of the POF allows sensing a rotation applied as well. The angle of rotation was obtained processing two images of the end facet of the fiber (one with the fiber in a reference position and one with the rotated fiber), using an intensity-based automatic image registration. The accuracy in the rotation calculation was of 0.01°.
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2
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Ghaffar A, Mehdi M, Hussain S, Hussian N, Ali S, JianHui S, Pang J, Liu W. The coupling of scattered-bend loss in POF based the displacement measurement sensor. SENSING AND BIO-SENSING RESEARCH 2020. [DOI: 10.1016/j.sbsr.2020.100351] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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3
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Li J, Liu J, Li C, Zhang H, Li Y. Wearable Wrist Movement Monitoring Using Dual Surface-Treated Plastic Optical Fibers. MATERIALS (BASEL, SWITZERLAND) 2020; 13:ma13153291. [PMID: 32722071 PMCID: PMC7436097 DOI: 10.3390/ma13153291] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Revised: 07/06/2020] [Accepted: 07/20/2020] [Indexed: 06/11/2023]
Abstract
Regarding high-sensitivity human wrist joint motion monitoring in exercise rehabilitation; we develop a pair of novel wearable and sensitivity-enhanced plastic optical fiber (POF) strain sensors consisting of an etched grating fiber and a side-polished fiber stitched into a polyamide wrist brace. The two flexible and surface-treated fibers are; respectively; featured with an etched periodic gratings with a pitch of 6 mm and a depth of 0.5 mm and a D-shaped side-polished zone of ~300 µm depth and ~30 mm length; which, correspondingly, show the sensitivities of around 0.0176/° and 0.0167/° in a normalized bending angle by far larger than a conventional commercial POF, because it achieves a more sensitive strain-induced evanescent field interaction with the side-machined fibers. Moreover, in terms of the sensor response to bending deformation in the range of -40°~+40°, the former exhibits a better sensitivity in lower angle change, while the latter is superior as the bending angle increases; thereby arranging the two modified POFs separately at the side and back of the human wrist, in order to decouple the wrist joint behaviors induced by typical flexion-extension or abduction-adduction movements. Then, the circular and pentagonal wrist motion trajectory patterns are investigated, to demonstrate the maximum average single-axis motion error of 2.94° via the transformation of spatial angle to plane coordinate for the fabricated couple of POF sensors, which is lower than a recognized standard of 5°, thus suggesting the great potential in wearable exercise rehabilitation of human joints in the field of medical treatment and healing.
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Affiliation(s)
- Jing Li
- School of Smart City, Beijing Union University, Beijing 100101, China;
| | - Jian Liu
- School of Instrumentation and Optoelectronic Engineering, Beihang University, Beijing 100191, China; (J.L.); (H.Z.)
- Shenzhen Institute of Beihang University, Shenzhen 518063, China
| | - Cheng Li
- School of Instrumentation and Optoelectronic Engineering, Beihang University, Beijing 100191, China; (J.L.); (H.Z.)
- Shenzhen Institute of Beihang University, Shenzhen 518063, China
| | - Hui Zhang
- School of Instrumentation and Optoelectronic Engineering, Beihang University, Beijing 100191, China; (J.L.); (H.Z.)
| | - Yizuo Li
- School of Smart City, Beijing Union University, Beijing 100101, China;
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An Analytical Model for Describing the Power Coupling Ratio between Multimode Fibers with Transverse Displacement and Angular Misalignment in an Optical Fiber Bend Sensor. SENSORS 2019; 19:s19224968. [PMID: 31739550 PMCID: PMC6891536 DOI: 10.3390/s19224968] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/19/2019] [Revised: 10/27/2019] [Accepted: 11/08/2019] [Indexed: 11/26/2022]
Abstract
The power coupling ratio between step-index multimode fibers caused by combined transversal and angular misalignment is calculated. A theoretical description of the coupling efficiency between two optical fibers based on geometrical optics is provided. The theoretical calculations are collaborated by experiments, determining the power coupling ratio between three output fibers with an axial offset and angular misalignment with a single input fiber. The calculation results are in good agreement with experimental results obtained using a previously fabricated optical fiber sensor for monitoring physiological parameters in clinical environments. The theoretical results are particularly beneficial for optimizing the design of optical fiber bending sensors that are based on power coupling loss (intensity) as the measurement interrogation requires either axial displacement, angular misalignment, or both.
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5
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Polymer Optical Fiber Sensors in Healthcare Applications: A Comprehensive Review. SENSORS 2019; 19:s19143156. [PMID: 31323734 PMCID: PMC6679278 DOI: 10.3390/s19143156] [Citation(s) in RCA: 85] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/15/2019] [Revised: 07/08/2019] [Accepted: 07/15/2019] [Indexed: 01/15/2023]
Abstract
Advances in medicine and improvements in life quality has led to an increase in the life expectancy of the general population. An ageing world population have placed demands on the use of assistive technology and, in particular, towards novel healthcare devices and sensors. Besides the electromagnetic field immunity, polymer optical fiber (POF) sensors have additional advantages due to their material features such as high flexibility, lower Young’s modulus (enabling high sensitivity for mechanical parameters), higher elastic limits, and impact resistance. Such advantages are well-aligned with the instrumentation requirements of many healthcare devices and in movement analysis. Aiming at these advantages, this review paper presents the state-of-the-art developments of POF sensors for healthcare applications. A plethora of healthcare applications are discussed, which include movement analysis, physiological parameters monitoring, instrumented insoles, as well as instrumentation of healthcare robotic devices such as exoskeletons, smart walkers, actuators, prostheses, and orthosis. This review paper shows the feasibility of using POF sensors in healthcare applications and, due to the aforementioned advantages, it is possible to envisage a further widespread use of such sensors in this research field in the next few years.
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Casas J, Leal-Junior A, Díaz CR, Frizera A, Múnera M, Cifuentes CA. Large-Range Polymer Optical-Fiber Strain-Gauge Sensor for Elastic Tendons in Wearable Assistive Robots. MATERIALS (BASEL, SWITZERLAND) 2019; 12:E1443. [PMID: 31058841 PMCID: PMC6539067 DOI: 10.3390/ma12091443] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Revised: 04/19/2019] [Accepted: 04/29/2019] [Indexed: 11/16/2022]
Abstract
This paper presents the development and validation of a polymer optical-fiber strain-gauge sensor based on the light-coupling principle to measure axial deformation of elastic tendons incorporated in soft actuators for wearable assistive robots. An analytical model was proposed and further validated with experiment tests, showing correlation with a coefficient of R = 0.998 between experiment and theoretical data, and reaching a maximum axial displacement range of 15 mm and no significant hysteresis. Furthermore, experiment tests were carried out attaching the validated sensor to the elastic tendon. Results of three experiment tests show the sensor's capability to measure the tendon's response under tensile axial stress, finding 20.45% of hysteresis in the material's response between the stretching and recovery phase. Based on these results, there is evidence of the potential that the fiber-optical strain sensor presents for future applications in the characterization of such tendons and identification of dynamic models that allow the understanding of the material's response to the development of more efficient interaction-control strategies.
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Affiliation(s)
- Jonathan Casas
- Biomedical Engineering Department, Colombian School of Engineering Julio Garavito, Bogotá 111166, Colombia.
| | - Arnaldo Leal-Junior
- Graduate Program of Electrical Engineering, Federal University of Espirito Santo, Vitoria 29075-910, Brazil.
| | - Camilo R Díaz
- Graduate Program of Electrical Engineering, Federal University of Espirito Santo, Vitoria 29075-910, Brazil.
| | - Anselmo Frizera
- Graduate Program of Electrical Engineering, Federal University of Espirito Santo, Vitoria 29075-910, Brazil.
| | - Marcela Múnera
- Biomedical Engineering Department, Colombian School of Engineering Julio Garavito, Bogotá 111166, Colombia.
| | - Carlos A Cifuentes
- Biomedical Engineering Department, Colombian School of Engineering Julio Garavito, Bogotá 111166, Colombia.
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A Polymer Optical Fiber Temperature Sensor Based on Material Features. SENSORS 2018; 18:s18010301. [PMID: 29351258 PMCID: PMC5795855 DOI: 10.3390/s18010301] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/30/2017] [Revised: 01/12/2018] [Accepted: 01/16/2018] [Indexed: 11/16/2022]
Abstract
This paper presents a polymer optical fiber (POF)-based temperature sensor. The operation principle of the sensor is the variation in the POF mechanical properties with the temperature variation. Such mechanical property variation leads to a variation in the POF output power when a constant stress is applied to the fiber due to the stress-optical effect. The fiber mechanical properties are characterized through a dynamic mechanical analysis, and the output power variation with different temperatures is measured. The stress is applied to the fiber by means of a 180° curvature, and supports are positioned on the fiber to inhibit the variation in its curvature with the temperature variation. Results show that the sensor proposed has a sensitivity of 1.04 × 10−3 °C−1, a linearity of 0.994, and a root mean squared error of 1.48 °C, which indicates a relative error of below 2%, which is lower than the ones obtained for intensity-variation-based temperature sensors. Furthermore, the sensor is able to operate at temperatures up to 110 °C, which is higher than the ones obtained for similar POF sensors in the literature.
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Bent Fiber Sensor for Preservative Detection in Milk. SENSORS 2016; 16:s16122094. [PMID: 27941703 PMCID: PMC5191074 DOI: 10.3390/s16122094] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Revised: 11/29/2016] [Accepted: 12/06/2016] [Indexed: 11/16/2022]
Abstract
A fiber optic sensor sensitive to refractive index changes of the outer region of the fiber cladding is presented. The sensor uses bent plastic optical fibers in different bending lengths to increase sensitivity. Measurements were made for low-fat milk, the refractive index of which is altered by some preservatives such as formaldehyde, hydrogen peroxide, and sodium carbonate. Concentrations of the preservatives in the milk were changed between 0% and 14.3% while the refractive indices occurred between 1.34550 and 1.35093 for the minimum (0%) and maximum (14.286%) concentrations of sodium carbonate, respectively. Due to bending-induced sensitivity, the sensor is able to detect refractive index changes less of than 0.4%. The results show that there is excellent linearity between the concentration and normalized response of the sensor.
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Li Y, Guan K, Hu Z, Chen Y. An Optical Fiber Lateral Displacement Measurement Method and Experiments Based on Reflective Grating Panel. SENSORS (BASEL, SWITZERLAND) 2016; 16:s16060808. [PMID: 27271624 PMCID: PMC4934234 DOI: 10.3390/s16060808] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/10/2016] [Revised: 05/25/2016] [Accepted: 05/30/2016] [Indexed: 06/06/2023]
Abstract
An optical fiber sensing method based on a reflective grating panel is demonstrated for lateral displacement measurement. The reflective panel is a homemade grating with a periodic variation of its refractive index, which is used to modulate the reflected light intensity. The system structure and operation principle are illustrated in detail. The intensity calculation and simulation of the optical path are carried out to theoretically analyze the measurement performance. A distinctive fiber optic grating ruler with a special fiber optic measuring probe and reflective grating panel is set up. Experiments with different grating pitches are conducted, and long-distance measurements are executed to accomplish the functions of counting optical signals, subdivision, and discerning direction. Experimental results show that the proposed measurement method can be used to detect lateral displacement, especially for applications in working environments with high temperatures.
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Affiliation(s)
- Yuhe Li
- Department of Precision Instruments, Tsinghua University, State Key Laboratory of Precision Measurement Technology and Instruments, Beijing 100084, China.
| | - Kaisen Guan
- Department of Precision Instruments, Tsinghua University, State Key Laboratory of Precision Measurement Technology and Instruments, Beijing 100084, China.
| | - Zhaohui Hu
- Department of Precision Instruments, Tsinghua University, State Key Laboratory of Precision Measurement Technology and Instruments, Beijing 100084, China.
| | - Yanxiang Chen
- Department of Precision Instruments, Tsinghua University, State Key Laboratory of Precision Measurement Technology and Instruments, Beijing 100084, China.
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Tapetado Moraleda A, Sánchez Montero D, Webb DJ, Vázquez García C. A self-referenced optical intensity sensor network using POFBGs for biomedical applications. SENSORS 2014; 14:24029-45. [PMID: 25615736 PMCID: PMC4299098 DOI: 10.3390/s141224029] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/24/2014] [Revised: 12/01/2014] [Accepted: 12/09/2014] [Indexed: 11/16/2022]
Abstract
This work bridges the gap between the remote interrogation of multiple optical sensors and the advantages of using inherently biocompatible low-cost polymer optical fiber (POF)-based photonic sensing. A novel hybrid sensor network combining both silica fiber Bragg gratings (FBG) and polymer FBGs (POFBG) is analyzed. The topology is compatible with WDM networks so multiple remote sensors can be addressed providing high scalability. A central monitoring unit with virtual data processing is implemented, which could be remotely located up to units of km away. The feasibility of the proposed solution for potential medical environments and biomedical applications is shown.
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Affiliation(s)
- Alberto Tapetado Moraleda
- Universidad Carlos III de Madrid, Displays and Photonics Applications Group, Electronics Technology Department, Avda Universidad 30, Leganés 28911, Spain.
| | - David Sánchez Montero
- Universidad Carlos III de Madrid, Displays and Photonics Applications Group, Electronics Technology Department, Avda Universidad 30, Leganés 28911, Spain.
| | - David J Webb
- Aston Institute of Photonic Technologies, Aston University, B4 7ET Birmingham, UK.
| | - Carmen Vázquez García
- Universidad Carlos III de Madrid, Displays and Photonics Applications Group, Electronics Technology Department, Avda Universidad 30, Leganés 28911, Spain.
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Plastic optical fibre sensor for spine bending monitoring with power fluctuation compensation. SENSORS 2013; 13:14466-83. [PMID: 24233073 PMCID: PMC3871115 DOI: 10.3390/s131114466] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/21/2013] [Revised: 10/14/2013] [Accepted: 10/18/2013] [Indexed: 11/21/2022]
Abstract
This paper presents the implementation of power fluctuation compensation for an intensity-based optical fibre bending sensor aimed at monitoring human spine bending in a clinical environment. To compensate for the light intensity changes from the sensor light source, a reference signal was provided via the light reflection from an aluminum foil surface fixed at a certain distance from the source fibre end tips. From the results, it was found that the investigated sensor compensation technique was capable of achieving a 2° resolution for a bending angle working range between 0° and 20°. The study also suggested that the output voltage ratio has a 0.55% diversion due to input voltage variation between 2.9 V and 3.4 V and a 0.25% output drift for a 2 h measurement. With the achieved sensor properties, human spine monitoring in a clinical environment can potentially be implemented using this approach with power fluctuation compensation.
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