Optical fiber sensors array to identify beverages by their odor

Four optical fiber sensors have been grouped in an array which is able to distinguish odors of different drinks. The sensing materials employed have been deposited onto optical fibers following the electrostatic self assembly method. The responses have been characterized in terms of reflected optical power; more specifically, the dynamic range and the recovery of each device have been used to discriminate between the samples. Data mining techniques based on the combination of principal component analysis and artificial neural networks are performed. The final system is trained to distinguish between grape juice, wine, and vinegar by using a set of one hundred samples of each one. Furthermore, the array can be located at up to 6 km away from the optical header, offering the possibility of in situ measurements.Peer reviewe

Optimization of single mode fibre sensors to detect organic vapours

The construction of single mode optical fibre (SMF) sensors to handle with volatile organic compounds (VOCs), has been optimized to operate at the third telecommunication window (1550 nm). The main motivation is to take advantage of the photonic devices used in telecommunication systems that makes easier sensors multiplexing. Moreover, the low transmission attenuation at that wavelength offers the possibility of remote sensing. The sensing materials used suffer reversible structural alterations in the presence of VOC, such as colour change, which are detectable with a photonic system. Following the Electrostatic Self Assembly method (ESAm), a nanostructure is constructed onto cleaved ended SMF, which is doped with a sensing material. The fabrication of this type of sensors was focused on multimode fibres (MMF) and in the visible spectral range (VIS) so far. The implementation has been adapted to SMF and to operate around 1550 nm, specifically, by easing the adsorption of the VOCs molecules. It has been observed that the sensing material affects the morphology of the nanostructures as well and so, to the sensors response. The devices implemented show a potential use in the identification of single and complex mixtures of VOCs. © 2011 Elsevier B.V.The authors would like to acknowledge the financial support from the Spanish Ministerio de Educación y Ciencia through projects TEC2010-17805 and TEC2010-20224-C02-01.Peer Reviewe

Volatile-organic-compound optic fiber sensor using a gold-silver vapochromic complex

7 pages, 6 figures, 2 tables.We describe a new gold-silver complex based on 2,2-bipyridine, whose formula is {Au2Ag2(C6F5)4[(C5H4N)-(C5H4N)]2}n, used to detect volatile organic compounds (VOCs) such as ethanol, methanol, and acetic acid. This organometallic material is presented in the form of bright yellow powder, and suffers a change in its optical properties when it is exposed to VOCs. A new fiber optic sensor is presented based on the properties of a new vapochromic material. The sensor works in a reflection configuration and consists of an optic fiber pigtail (core diameter is 200 µm and cladding is 230 µm) on the cleaved end of which the vapochromic material, previously mixed with a commercially available solvent, Liquicoat®, is deposited by using the dip-coating technique. Using an optical source and a photodetector, it is possible to detect and quantify the change in reflected intensity-modulated signal when the sensor is exposed to VOC inside a sealed chamber. This behavior can be related to the VOC concentration. The study of the sensor's response is made at a specific wavelength for different VOC concentrations. Limits of detection of 2.16, 1.73, and 3.73 mg/L of vapors of ethanol, methanol, and acetic acid vapors, respectively, are attained.The authors gratefully acknowledge the financial support of the FPU Grant of the Ministry of Education, Culture and Sport (reference AP2002-1033), Projects MAT 2003- 09074-C02-01, CICyT TIC2003-00909, and BQU2002- 04090-C02-02 of the Ministry of Science and Technology, and to Consejería de Medio Ambiente de la Junta de Andalucía and Gobierno de Navarra.Peer reviewe

Volatile alcoholic compounds fibre optic nanosensor

6 pages, 9 figures.A fibre optic sensor for detection of some volatile organic compounds (VOCs) is presented. This device is based on a new vapochromic material of formula [Au2Ag2(C6F5)4(C6H5N)2], presented in the form of bright red powders. This material changes its optical properties as colour or refractive index when exposed to some organic vapours, recovering its original state when vapours get disappeared. The sensor head consists of a nanometer-scale Fizeau interferometer doped with the vapochromic material, built onto a cleaved end of a multimode fibre optic pigtail by using the electrostatic self-assembly method (ESA). The fibre optic sensor is used in a reflection scheme, so the other extreme of the optical fibre pigtail is connected to an optical coupler, completing the set-up with an optical source that generates an interrogating signal and an optical detector to register the intensity modulated reflected measure. The response of the sensor has been characterized taking measures of its absorbance spectra and the intensity modulated reflected signal at 850 nm for different alcohols. Changes up to 3 dB in the reflected optical power were registered.This work was supported by Spanish Ministerio de Ciencia y Tecnología and FEDER Research Grants CICYT-TIC 2003-000909, CICYT-TEC 2004-05936-C02-01/MIC, and CICYT-BQU2002-04090-CO2-02.Peer reviewe

Bone mineral density and body composition among athletes: Lightweight versus heavyweight sports

Objectives: Energy restriction and weight loss techniques are associated with adverse effects on bone mineral density (BMD) whilst participation in sports is known to be beneficial for skeletal health. However, it is not entirely clear the skeletal health status in lightweight sports where participants often use weight management techniques to attain relatively low mass. Therefore, the aim of this study is to evaluate the differences in BMD and body composition among athletes engaged in weight restricted and non-weight restricted sports.Published versio

Half hip fracture patients are reportedly ‘worse’ than dead as based on health-related quality of life at the time of admission, with partial recovery at 1 and 4-months follow-up: the spare-hip prospective cohort

Objective: To estimate the impact of hip fracture on health-related quality of life (HRQoL) up to 4 months post-fracture