FBG Multifunctional pH Sensor - Monitoring the pH Rain in Cultural Heritage

A new era of pollution requires an important focus on the conservation of archaeological sites and monuments. In the last years great efforts were required to develop various sensors for different tasks. The fiber Bragg grating (FBG) was one of the most studied thanks to the multitude of applications and the surprising performances. An original fiber optic sensor that combines the fiber Bragg gratings<strong> </strong>with a pH responsive polymer coating for monitoring the pH of the rains on critical and prestigious monuments is proposed. The core consists of four different materials, which makes the sensor very innovative and allowing it to reach a high sensitivity. In this study, the setup arrangement of the optical sensor is modeled with COMSOL Multiphysics (Wave Optics Module), based on the FEM (Finite Element Method) solver. Monitoring the pH of water can be used by experts to predict and control the corrosion phenomenon of specific materials, especially limestone and marble, thus scheduling the timely restoration.

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Ex-Vivo Measurement of the pH in Aqueous Humor Samples by a Tapered Fiber-Optic Sensor

Sensors ◽

10.3390/s21155075 ◽

2021 ◽

Vol 21 (15) ◽

pp. 5075

Author(s):

Ondřej Podrazký ◽

Jan Mrázek ◽

Jana Proboštová ◽

Soňa Vytykáčová ◽

Ivan Kašík ◽

...

Keyword(s):

Cataract Surgery ◽

Aqueous Humor ◽

Fiber Optic ◽

Ex Vivo ◽

Sol Gel ◽

Ph Sensor ◽

Fiber Optic Sensor ◽

Optic Sensor ◽

Tapered Optical Fiber ◽

Practical Demonstration

A practical demonstration of pH measurement in real biological samples with an in-house developed fiber-optic pH sensor system is presented. The sensor uses 8-hydroxypyrene-1,3,6-trisulfonate (HPTS) fluorescent dye as the opto-chemical transducer. The dye is immobilized in a hybrid sol-gel matrix at the tip of a tapered optical fiber. We used 405 nm and 450 nm laser diodes for the dye excitation and a photomultiplier tube as a detector. The sensor was used for the measurement of pH in human aqueous humor samples during cataract surgery. Two groups of patients were tested, one underwent conventional phacoemulsification removal of the lens while the other was subjected to femtosecond laser assisted cataract surgery (FLACS). The precision of the measurement was ±0.04 pH units. The average pH of the aqueous humor of patients subjected to FLACS and those subjected to phacoemulsification were 7.24 ± 0.17 and 7.31 ± 0.20 respectively.

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High Sensitivity Humidity Fiber-Optic Sensor Based on All-Agar Fabry–Perot Interferometer

IEEE Sensors Journal ◽

10.1109/jsen.2018.2828134 ◽

2018 ◽

Vol 18 (12) ◽

pp. 4879-4885 ◽

Cited By ~ 12

Author(s):

Bo Wang ◽

Jiajun Tian ◽

Ling Hu ◽

Yong Yao

Keyword(s):

Fiber Optic ◽

High Sensitivity ◽

Fiber Optic Sensor ◽

Optic Sensor ◽

Fabry Perot

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A Bio-Compatible Fiber Optic pH Sensor Based on a Thin Core Interferometric Technique

Photonics ◽

10.3390/photonics6010011 ◽

2019 ◽

Vol 6 (1) ◽

pp. 11 ◽

Cited By ~ 4

Author(s):

Magnus Engholm ◽

Krister Hammarling ◽

Henrik Andersson ◽

Mats Sandberg ◽

Hans-Erik Nilsson

Keyword(s):

Fiber Optic ◽

Ph Sensor ◽

High Sensitivity ◽

Single Mode ◽

Measurement Range ◽

Ph Sensitive ◽

Fiber Optic Sensor ◽

Design Parameters ◽

Sensitive Material ◽

Interferometric Technique

There is an increasing demand for compact, reliable and versatile sensor concepts for pH-level monitoring within several industrial, chemical as well as bio-medical applications. Many pH sensors concepts have been proposed, however, there is still a need for improved sensor solutions with respect to reliability, durability and miniaturization but also for multiparameter sensing. Here we present a conceptual verification, which includes theoretical simulations as well as experimental evaluation of a fiber optic pH-sensor based on a bio-compatible pH sensitive material not previously used in this context. The fiber optic sensor is based on a Mach-Zehnder interferometric technique, where the pH sensitive material is coated on a short, typically 20-25 mm thin core fiber spliced between two standard single mode fibers. The working principle of the sensor is simulated by using COMSOL Multiphysics. The simulations are used as a guideline for the construction of the sensors that have been experimentally evaluated in different liquids with pH ranging from 1.95 to 11.89. The results are promising, showing the potential for the development of bio-compatible fiber optic pH sensor with short response time, high sensitivity and broad measurement range. The developed sensor concept can find future use in many medical- or bio-chemical applications as well as in environmental monitoring of large areas. Challenges encountered during the sensor development due to variation in the design parameters are discussed.

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