The employability of photonics technology in the modern era's highly demanding and sophisticated domain of aerospace and submarines has been an appealing challenge for the scientific communities. In ...this paper, we review our main results achieved so far on the use of optical fiber sensors for safety and security in innovative aerospace and submarine applications. In particular, recent results of in-field applications of optical fiber sensors in aircraft monitoring, from a weight and balance analysis to vehicle Structural Health Monitoring (SHM) and Landing Gear (LG) monitoring, are presented and discussed. Moreover, underwater fiber-optic hydrophones are presented from the design to marine application.
In order to complete this set of three companion papers, in this last, we focus our attention on environmental monitoring by taking advantage of photonic technologies. After reporting on some ...configurations useful for high precision agriculture, we explore the problems connected with soil water content measurement and landslide early warning. Then, we concentrate on a new generation of seismic sensors useful in both terrestrial and under water contests. Finally, we discuss a number of optical fiber sensors for use in radiation environments.
Our group, involving researchers from different universities in Campania, Italy, has been working for the last twenty years in the field of photonic sensors for safety and security in healthcare, ...industrial and environment applications. This is the first in a series of three companion papers. In this paper, we introduce the main concepts of the technologies employed for the realization of our photonic sensors. Then, we review our main results concerning the innovative applications for infrastructural and transportation monitoring.
We present a very simple and versatile fiber optic sensor for liquid level measurements based on the Archimedes' law of buoyancy. It includes a proper mass suspended in the liquid with one end fixed ...to a fiber Bragg grating (FBG) strain sensor, while the remaining fiber termination is fixed to a rigid support. When the liquid level increases inside the tank, the load exerted by the suspended mass on the optical fiber is reduced as a consequence of the increase of the force acting on the immersed mass according to the Archimedes' law of buoyancy, leading to a reduction of the strain applied to the FBG. The proposed device is able to perform real time and continuous liquid level measurements, and is characterized by sensing features (such as sensitivity and operating range) that exclusively depend on the geometrical characteristics (e.g., shape, diameter, and length) of the suspended mass. Therefore, by a judicious selection of its geometrical features, the proposed device can be customized so as to suit the requirements for the specific application. In addition, the constitutive material of the attached mass can be properly selected in order to confer to the proposed platform the capability to operate in any kind of liquid. Here, as proof of principle, we exploited an aluminium cylindrical mass having a radius of 8 mm and a length of 30 cm, and experimentally demonstrated the capability of the realized device to measure the water level inside a beaker over a range of 25 cm with a sensitivity of ∼27 pm/cm, a resolution of ∼0.04 cm, and a repeatability error of ∼0.1% of the full scale reading. We also demonstrated, both theoretically and experimentally, the possibility to largely tune the sensing performances by acting on the cylinder radius. Obtained results pave the way for the exploitation of the proposed platform for accurate liquid level monitoring in large-scale storage tanks, useful both for petrochemical industry and for agricultural/residential applications.
Tissue elasticity is universally recognized as a diagnostic and prognostic biomarker for prostate cancer. As the first diagnostic test, the digital rectal examination is used since malignancy changes ...the prostate morphology and affects its mechanical properties. Currently, this examination is performed manually by the physician, with an unsatisfactory positive predictive value of 42%. A more objective and spatially selective technique is expected to provide a better prediction degree and understanding of the disease. To this aim, here we propose a miniaturized probe, based on optical fiber sensor technology, for mechanical characterization of the prostate with sub-millimeter resolution. Specifically, the optical system incorporates a customized Fiber Bragg Grating, judiciously integrated in a metallic cannula and moved by a robotic arm. The probe enables the local measurement of the force upon tissue indentation with a resolution of 0.97 mN. The system has been developed in such a way to be potentially used directly
in vivo
. Measurements performed on phantom tissues mimicking different stages of the prostatic carcinoma demonstrated the capability of our device to distinguish healthy from diseased zones of the prostate. The study on phantoms has been complemented with preliminary
ex vivo
experiments on real organs obtained from radical surgeries. Our findings lay the foundation for the development of advanced optical probes that, when integrated inside biopsy needle, are able to perform
in vivo
direct mechanical measurements with high sensitivity and spatial resolution, opening to new scenarios for early diagnosis and enhanced diagnostic accuracy of prostate cancer.
PDF