Riccardo Falciai

Long-term ambulatory enterogastric reflux monitoring. Validation of a new fiberoptic technique.

A new technique for the long-term ambulatory detection of enterogastric and nonacid gastroesophageal reflux has been conceived, developed, and validated. It is based on the use of a fiberoptic sensor that utilizes the optical properties of bile.In vitro studies have shown good precision, good stability, sensitivity of 2.5 μmol/liter bilirubin concentration, as well as a useful working range of 2.5–100 μmol/liter bilirubin concentration.In vivo studies have been performed in 29 subjects. Simultaneous gastric aspirations have allowed a comparison of fiberoptic system measurements both with spectrophotometric analysis and bile acid concentrations of corresponding gastric juice samples. Linear correlations were shown between fiberoptic assessment and both spectrophotometric and bile acid concentration findings (P<0.01). Simultaneous assessment of reflux with the fiberoptic system and cholescintigraphy has shown a 92.9% concordance as regards the presence or absence of reflux. Present results imply that the fiberoptic system is an important tool for the understanding of the clinical relevance of enterogastric and nonacid gastroesophageal reflux.

Long period gratings as solution concentration sensors

Abstract The on-line concentration measurement of solutions is of great interest in many industrial processes as a means of quality production control, in order to measure concentrations of harmful solutions or solutions that cannot be reached by the operator. An optical fiber long-period grating (LPG), tested for the refractometry of sodium chloride, calcium chloride and ethylene glycol aqueous solutions, is presented. Resolution values comparable to or even better than those offered by an Abbe refractometer, that is typically used in these types of measurements, are obtained.

New fiber optic sensor for ambulatory entero-gastric reflux detection

The problem of entero-gastric reflux is clinically relevant and none of the presently available techniques for its detection is satisfactory. Therefore, a portable fiber optic system for ambulatory reflux assessment has been conceived and developed. Two light emitting diodes (for signal and reference) and a suitable electronic circuit for signal processing are associated with a plastic fiber optic bundle. The working principle of the system is based on the characteristic absorption of bilirubin and bile around 450 nm. In-vitro results have shown good accuracy, linearity, and stability in the measurements of the fiber optic system. In-vivo results are promising.

Miniaturised Optical Fibre Sensor for Dew Detection Inside Organ Pipes

A new optical sensor for the continuous monitoring of the dew formation inside organ pipes was designed. This aspect is particularly critical for the conservation of organs in unheated churches since the dew formation or the condensation on the pipe surfaces can contribute to many kinds of physical and chemical disruptive mechanisms. The working principle is based on the change in the reflectivity which is observed on the surface of the fibre tip, when a water layer is formed on its distal end. Intensity changes of the order of 35% were measured, following the formation of the water layer on the distal end of a 400/430 m optical fibre. Long-term tests carried out placing the fibre tip inside the base of an in-house-made metallic foot of an organ pipe located in an external environment revealed the consistency of the proposed system.

Tapered multimode optical fibers for enhanced evanescent-wave absorption spectroscopy of liquids

This paper discusses the theoretical and experimental implications of tapering a multimode optical fiber with a view to its use in evanescent-wave absorption-spectroscopy. Good experimental results are obtained, showing the possibility of quadruplicating the absorbance efficiency. This easy and reproducible technique for taper fabrication is suitable for the implementation of both probes for spectroscopy and chemically-assisted fiber optic sensors.

Optical PMMA chip for multianalyte detection

In the present work an optical platform is described for the interrogation of a multichannel array for chemical and biochemical parameters. A fluorescent sensing layer is immobilised on the internal wall of the channel and the emitted light travels along the thickness of the channel and is detected with an optical fibre connected with a spectrum analyzer.

Solution concentration measurements by means of optical fiber long-period gratings

The measurement of the concentration of stock solutions, dilutions, oils, and water-soluble industrial fluids is of interest in many quality control industrial processes in order to check the concentration stability and abnormal aging effects. Off-line refractometers, such as the Abbe type, which offer a resolution of 0.2 percent, are commonly used. This paper presents an optical fiber long-period grating which has been tested for the refractometry of sodium chloride and calcium chloride aqueous solutions for a range of density varying from that of distilled water to that of a nearly-saturated condition.

Bile enterogastric reflux sensor using plastic optical fibers

Abstract A portable optical-fiber sensor for ambulatory assessment of the enterogastric reflux, based on the optical properties of the bile, was developed. It makes use of two light-emitting diodes and of an appropriate electronic circuit that processes the signals and provides the readout on a display. A suitable probe for in vivo measurements was designed. Plastic fiber bundles are used in order to obtain probe flexibility and low price. In vivo measurements performed on different patients show the superiority of this technique over existing methods.

Optical fibre bile sensor for entero-gastric reflux detection

Abstract A new method for entero-gastric reflux detection by optical fibres is described. Its working principle is based on the spectrophotometric properties of the bile and represents a direct method for the measurement of the reflux, showing many advantages in comparison with the traditional indirect methods of detection. On this basis, an optical fibre sensor was developed and industrialized, making use of two light-emitting diodes (for the signal and reference, respectively) and of a special electronic circuit which processes the signals and provides the read-out on a display. Measurements on several patients were carried out and the experimental results are discussed here.

Deformation monitoring of wooden works of art using FBG sensors

Wood support is an essential element of the works of art and is highly sensitive to the environmental climate modification. Wood deformations may have irreversible destructive effects on the work of art. The use of fiber Bragg grating (FBG) sensors for the quasi-distributed in-situ measurement and continuous monitoring of the painted wood panel deformations is proposed. FBG sensors have high resolution low invasivity and intrinsic safety. The effects of relative humidity changes were measured on a wood panel, by monitoring the deformations in the wood structure using an array of fiber Bragg gratings glued to different critical points.