Folco Senesi

Equivalent light dosimetry in museums with blue wool standards and optical fibers

A novel optical-fiber instrument is presented for the monitoring of lighting in a museum environment. It makes use of blue wool standard dosimeters, the light-induced color-fading of which is continuously monitored by means of a miniaturized optical-fiber spectrophotometer. Field tests performed at the Uffizi Gallery of Florence are presented.

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.

A sandwich assay for procalcitonin detection for POCT applications

A plastic biochip was developed for the detection of procalcitonin (PCT) and consists of a polymethylmethacrylate (PMMA) chip shaped in order to achieve several flow microchannels. A sandwich assay using a new antibody pairs is implemented with the capture antibody immobilized on the PMMA surface and the target antibody labelled with a fluorophore. A laser diode excites the fluorescent sensing layer. Thanks to the anisotropy of the fluorescence the emitted light travels along the thickness of the plastic material. The fluorescence coming out from the chip is collected by 1 mm plastic optical fibre and detected with a spectrum analyser.

Equivalent light dosimetry in museums with Blue Wool Standards and optical fibers

Blue Wool Standard (BWS) dosimeters, that have been officially adopted by the International Standards Organisation for photo-induced color variation, consist of a set of wool samples which progressively and irreversibly fade when exposed to light. The samples are loaded with different light-sensitive blue dyes to show color fading with varying sensitivities to light exposure. When BWSs are exposed under normal conditions, fading occurs because of exposure to light and to the combined action of light and other environmental facets. BWSs are therefore optimal transducers for performing dosimetry of equivalent light. BWS dosimeters in combination with a miniaturized optical fiber spectrophotometer were used for continuous and real-time light equivalent dosimetry, as applied to an appropriate indoor conservation of works of art. The continuous monitoring of the occurrence of risk situations makes it possible to slow down any color deterioration and to stabilize them where possible against further deterioration. The novel instrument presented in this paper has been installed since the beginning of November 2001 at the Uffizi Gallery in Florence, in the Geographic Maps Room. Field tests will last for several months, and will be performed also in other Rooms of the Gallery in order to highlight situations of particular risk.

A novel optical probe for pH sensing in gastro-esophageal apparatus

Monitoring gastric pH for long periods, usually 24 h, may be essential in analyzing the physiological pattern of acidity, in obtaining information on changes in activity during peptic ulcer disease, and in assessing the effect of antisecretory drugs. Gastro-esophageal reflux, which causes a pH decrease in the esophagus content from pH 7 even down to pH 2, can determine esophagitis with possible strictures and Barretts esophagus. One of the difficulties of the optical measurement of pH in the gastro-esophageal apparatus lies in the required extended working range from 1 to 8 pH units. The present paper deals with a novel optical pH sensor, using methyl red as optical pH indicator. Contrary to all acidbase indicators characterized by working ranges limited to 2-3 pH units, methyl red, after its covalent immobilization on controlled pore glass (CPG), is characterized by a wide working range which fits with the clinical requirements. The novel probe design here described is suitable for gastro-esophageal applications and allows the optimization of the performances of the CPG with the immobilised indicator. This leads to a very simple configuration characterized by a very fast response time.

Novel fiber tip sensor potentially suitable for gastric pH measurement

Monitoring pH for long periods, usually 24 h, in the stomach and in the esophagus may be essential in the diagnosis of gastro-esophageal diseases. The clinical range of interest is quite extended, between 1 to 8 pH units. Methyl red, after its covalent immobilization on controlled pore glass (CPG), is characterized by a working range which fits well with the clinical one. A novel probe, suitable for gastro-esophageal applications, was designed in order to optimize the performances of the colored CPG. This leads to a very simple probe configuration characterized by a very fast response.

A fluorescent immunoassay for the determination of procalcitonin and C-reactive protein

The discrimination of viral and bacterial sepsis is an important issue in intensive care patients. For this purpose, the simultaneous measurements of different analytes such as C-reactive protein (CRP), procalcitonin (PCT), myeloperoxidase, interleukines and neopterin, are necessary. A novel optical platform was designed and realised for the implementation of fluorescence-based immunoassays. The core of the optical platform is a plastic biochip, formed by a series of microchannels each of them devoted to the determination of a single analyte. Sandwich assays for CRP and PCT spiked in serum were performed in order to demonstrate the reliability of a multi-array device.

Point of care optical device for sepsis diagnosis

The discrimination of viral and bacterial sepsis is an important issue in intensive care patients. For this purpose, the simultaneous measurements of different analytes are necessary. Among the possible candidates, C-reactive protein (CRP) and procalcitonin (PCT) are probably the most important ones. A novel optical platform was designed and realised for the implementation of fluorescence-based immunoassays. The core of the optical platform is a plastic biochip, constituted by 13 microchannels (50 μm high, 600 μm width, 10 mm long) through which the sample flows. The sensing layer, where the immunochemical reaction takes place, is located on the upper part of each microchannel. The chip is interrogated with a novel optoelectronic platform, based on fluorescence anisotropy. A line-shaped beam from a 635-nm laser-diode excites perpendicularly the sensing layer and great many of the emitted remains entrapped inside the chip. The particular shape of the top of the chip allows to guide the emitted fluorescence along the same direction of the microchannel. The fluorescence which comes out on the lateral side from the chip is collected by a single plastic optical fibre and sent to an amplified photodiode. The device was characterised by the implementation of the sandwich assay for CRP and PCT spiked in serum. Limit of quantifications of 4.5 and of 6 μg L-1 in serum solution were achieved for CRP and PCT, respectively.

A compact optical system for the interrogation of microcantilevers

The present paper is concerned with the development of an optical system capable of interrogating an array of silicon microcantilevers. The use of a laser line-generator and of a CCD camera allows the simultaneous interrogation of the eight cantilevers of the chip without movable parts. The resolution achieved in terms of displacement of each cantilever end is better than 7.5 nm. As an example of the operation, the system has been characterized as a refractometer by filling the cell with liquids having different index of refraction.