We report an optical fiber multiparameter sensor for refractive index and temperature measurements. The proposed sensor is composed by a microcavity in multimode fiber, assisted by Bragg gratings (FBGs) in singlemode fiber. The microcavity is engraved in a multimode optical fiber by using the femtosecond laser micromachining. The sensor is characterized through microcavity immersion in water and based on its temperature variation. The results show that it is possible to obtain refractive index and temperature measurements with sensitivities of 1625 μW/RIU (refractive index unit) and of 0.23 μW/°C, with resolution of 1.8 × 10-4 RIU and of 1.3°C.
The aim of the study is to demonstrate the potential of the fibre Braggs grating (FBG) in the measurement of different jaw movements that are performed for patients with occlusal parafunction using occlusal splints. Two silicon plates each 2mm are used, the fibre optic sensor is positioned in the maxillary left first molar region above the point of contact with opposing tooth after pressing the first plate on the model. Then the second silicon plate is pressed. The device has a final thickness of 2 mm. The occlusal splint is installed in the mouth of the patient who underwent different movements on occlusal splint. The maximum frequency bite is monitored. The results demonstrate that the bite shows a difference between grinding and clenching movements. The curves behaviour patterns are presented in order to show these different comparisons. Therefore, it is concluded that the fibre Braggs grating consists in an efficient method for monitoring the mechanical behaviour bite of patients with occlusal splints.
This study describes the evolution of a punctual method to determine the bite force. Now the fiber Bragg grating sensor is encapsulated in minimal material between uppers and lowers first molars, at the moment of occlusion, avoiding precontacts between the other teeth in a dentition model. The gypsum dentition castings were performed in semi-adjustable articulator in the occluded situation to maintain angulations of the occlusal plane of a volunteer. The sensor was characterized using loads from 0 to 90 N. Forces of about 0.0112 nm/N were found between right uppers and lowers first molars.
A 10 μm (length) × 75 μm (depth) open channel is fabricated in fibre Bragg gratings (FBG) by femtosecond laser micromachining. The FBG Fabry-Perot (FP) cavity formed by this complex structure has a length of 4 mm; value estimated from interference spectrum for the air open channel. Reflection spectra of FBG FP cavity as a function of the temperature shows the cavity phase change. The sensor is thermally characterized by filling polymer in the channel and subsequent UV curing; the results show a period shift of approximately 12 x10-3, value obtained of interferometer pattern for 30°C temperature range.
The aim of the study is to develop a new punctual method to determine the human bite force, between uppers and lowers first molars, at the moment of occlusion in maximum intercuspation. Fibre optic Bragg gratings are encapsulated in an acetate splint made by casting of a volunteer lower dentition. Splint sensor was positioned into the mouth to be pressured with minimal occlusal interference. The transversal pressure on the FBG was acquired at the moment of before occlusion (free), occlusion and biting. The measured forces were 12N during occlusion and 28N bite force, between right uppers and lowers first molars.
We report the fabrication of an hybrid fibre optic and T-shaped microstructrure inscribed in soda lime microscope slides by using femtosecond laser irradiation technique. that allow to construct true 3-D structures. Within the T-shaped structure a FBG was inserted and glued with photopolymer adhesive. The hybrid structure is sensitive to hydrostatic pressure. Calibration load tests were performed in the range 0 - 100 N.
We report a nonlinear temperature dependence of the birefringence in polarization maintaining fibre optics, obtained using Bragg gratings recorded in different types of fibres and thermal regeneration. Results show the birefringence quenching is also reversible but with different final values.
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