122 Crack growth measurements on a composite specimen using fiber optic sensors

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Smart textile for respiratory monitoring and thoraco-abdominal motion pattern evaluation

The use of wearable systems for monitoring vital parameters has gained wide popularity in several medical fields. The focus of the present study is the experimental assessment of a smart textile based on 12 fiber Bragg grating sensors for breathing monitoring and thoraco‐abdominal motion pattern analysis. The feasibility of the smart textile for monitoring several temporal respiratory parameters (ie, breath‐by‐breath respiratory period, breathing frequency, duration of inspiratory and expiratory phases), volume variations of the whole chest wall and of its compartments is performed on 8 healthy male volunteers. Values gathered by the textile are compared to the data obtained by a motion analysis system, used as the reference instrument. Good agreement between the 2 systems on both respiratory period (bias of 0.01 seconds), breathing frequency (bias of −0.02 breaths/min) and tidal volume (bias of 0.09 L) values is demonstrated. Smart textile shows good performance in the monitoring of thoraco‐abdominal pattern and its variation, as well

Linearly chirped fiber Bragg grating response to thermal gradient: from bench tests to the real-time assessment during in vivo laser ablations of biological tissue

The response of a fiber optic sensor [linearly chirped fiber Bragg grating (LCFBG)] to a linear thermal gradient applied on its sensing length (i.e., 1.5 cm) has been investigated. After these bench tests, we assessed their feasibility for temperature monitoring during thermal tumor treatment. In particular, we performed experi- ments during ex vivo laser ablation (LA) in pig liver and in vivo thermal ablation in animal models (pigs). We investigated the following: (i) the relationship between the full width at half maximum of the LCFBG spectrum and the temperature difference among the extremities of the LCFBG and (ii) the relationship between the mean spectrum wavelength and the mean temperature acting on the LCFBG sensing area. These relationships showed a linear trend during both bench tests and LA in animal models. Thermal sensitivity was significant although different values were found with regards to bench tests and animal experiments. The linear trend and significant sensitivity allow hypothesizing a future use of this kind of sensor to monitor both temperature gradient and mean temperature within a tissue undergoing thermal treatment

Use of Fibre Bragg Grating sensors for Gas Electron Multiplier HEP detectors

The GE1/1 CMS muon system upgrade consists of 144 GEM chambers based on the triple-GEM technology (three GEM foils flat parallel closely spaced). The GE1/1 assembly procedure employs a mechanical stretching procedure to apply tension to the GEM foils by means of a series of lateral stretchers. This novel technology allows mechanical assembly of the GEM chamber without the use of internal spacers or glue. This procedure reduces the assembly time and allows the user to replace one or more GEM foils after the chamber has been assembled. However this mechanical stretching technique needs to be validated to prove that the mechanical stretching technique applies a uniform tensile load on the triple-GEM stack able to fulfil the design specifications which require that foils are planar and uniformly spaced

Fiber Bragg Grating Measuring System for Simultaneous Monitoring of Temperature and Humidity in Mechanical Ventilation

During mechanical ventilation, the humidification of the dry air delivered by the mechanical ventilator is recommended. Among several solutions, heated wire humidifiers (HWHs) have gained large acceptance to be used in this field. The aim of this work is to fabricate a measuring system based on fiber Bragg grating (FBG) for the simultaneous monitoring of gas relative humidity (RH) and temperature, intended to be used for providing feedback to the HWHs’ control. This solution can be implemented using an array of two FBGs having a different center wavelength. Regarding RH monitoring, three sensors have been fabricated by coating an FBG with two different moisture-sensitive and biocompatible materials: the first two sensors were fabricated by coating the grating with a 3 mm × 3 mm layer of agar and agarose; to investigate the influence of the coating thickness to the sensor response, a third sensor was developed with a 5 mm × 5 mm layer of agar. The sensors have been assessed in a wide range of RH (up to 95%) during both an ascending and a subsequent descending phase. Only the response of the 3 mm × 3 mm-coated sensors were fast enough to follow the RH changes, showing a mean sensitivity of about 0.14 nm/% (agar-coated) and 0.12 nm/% (agarose-coated). The hysteresis error was about <10% in the two sensors. The contribution of temperature changes on these RH sensors was negligible. The temperature measurement was performed by a commercial FBG insensitive to RH changes. The small size of these FBG-based sensors, the use of biocompatible polymers, and the possibility to measure both temperature and RH by using the same fiber optic embedding an array of two FBGs make intriguing the use of this solution for application in the control of HWHs

Fiber Bragg Grating interrogation system based on a novel integrated optical filter

Abstract— An innovative interrogation system prototype for structural sensing based on a high-performance electro-optic edge filter on glass is presented here. It provides a wavelength dependent transmittance with a linear relationship between the Bragg wavelength shift and the output intensity change of the filter. The resulting device is the demonstration of a simple and inexpensive technology to implement low cost FBG sensors monitoring system based on innovative integrated optic functional component on glass

Sistema di interrogazione di sensori fbg basato su un filtro ottico integrato a materiale composito

An interrogation system for structural sensing based on an innovative electrooptic filter is presented, providing a wavelength–dependent transmittance and offering a linear relationship between the FBG wavelength shift and the output intensity change of the filter

Optical interrogation system based on holographic soft matter filter

We present an optical interrogation system based on a holographic soft-matter filter. It provides a wavelength-dependent transmittance, with a linear relation between Bragg wavelength shift and variation in the filter output intensity. This is the demonstration of a simple and inexpensive technology to implement a, low cost, monitoring system based on a fiber Bragg grating sensor