Dinesh Babu Duraibabu

Fibre optic sensors (FOSs) have developed as a transformative technology in healthcare, often offering unparalleled accuracy and sensitivity in monitoring various physiological and biochemical parameters. Their applications range from tracking vital signs to guiding minimally invasive surgeries, enabling advancements in medical diagnostics and treatment. However, the integration of FOSs into biomedical applications faces numerous challenges. This article describes some challenges for adopting FOSs for biomedical purposes, exploring technical and practical obstacles, and examining innovative solutions. Significant challenges include biocompatibility, miniaturization, addressing signal processing complexities, and meeting regulatory standards. By outlining solutions to the stated challenges, it is intended that this article provides a better understanding of FOS technologies in biomedical settings and their implementation. A broader appreciation of the technology, offered in this article, enhances patient care and improved medical outcomes.

This paper presents a start to finish approach on the inspection and repair of damaged ship hulls in water. The repair of ship hulls in water has been made viable by recent developments in Friction Stir Welding (FSW) of steels. The project is a European Union (EU) funded collaboration involving a variety of academic and industry partners aiming to increase the productivity of small and medium sized EU shipyards. This paper outlines the overall procedure of a repair mission while focusing on the inspection task by use of Remotely Operated Vehicles (ROV), as performed in a variety of environments on a fractured plate made from ship grade steel. The equipment and processing procedures are detailed with discussion demonstrating the capabilities in generating the required quality of 3D models in order for defects to be identified and for a sufficiently sized repair patch to be designed.

Humidity is a prominent pollutant that must be regulated as well as a process variable that must be assessed in industrial applications. Humidity can degrade service quality, impair manufacturing equipment, and hikes the operating expenses considerably. Currently, demand for accurate humidity sensing significantly increases in various fields. Optical based sensors seek attention towards humidity sensing due to their inherent properties like multiplexing, accuracy and durability. For transducing humidity into a measurable parameter, coating materials contribute significantly. The performance of coating materials used for humidity monitoring was analyzed in terms of their thickness, response time, sensitivity and their compatibility in harsh environments. Four different types of coating materials such as PVAc, Agarose, PMMA and Polyimide were analyzed in terms of sensitivity, thickness, response time, resolution limit of detection and application.

In this paper, we investigate the methods to be used in the inspection of damaged ship hulls in water at sea, as part of the European Union (EU) Robotic Survey, Repair and Agile Manufacture (RESURGAM) Project. Employing underwater robotics equipped with camera or laser sensors, along with robust control and positioning systems, 3D models of the damaged section(s) can be produced with a goal of providing sufficient information for the subsequent design of repair patch(es), and ultimately the application of this repair to the ship. This work will allow damaged ships at sea to seek repair without the need for access to a dry dock. Preliminary results from recent field operations are included in this paper, with further field research to be carried out later this year.

Continuous and accurate monitoring of oceanic physical parameters, including salinity and depth, is essential for naval surveillance, communication and environmental monitoring. In this regard, Fibre Bragg Grating (FBG) sensors are being implemented as highly accurate temperature and strain sensors for diverse applications. However, discriminating the individual effects of the two parameters, salinity and depth, is challenging, because both have to be transduced from the strain response. In this paper, we present a innovative approach, by implementing the amplitude of the FBG’s reflected spectrum as a second responding element. We have theoretically and experimentally demonstrated that the reflected amplitude of an FBG is inversely proportional to strain, and used this principle for salinity and depth measurement. Using the Bragg wavelength, we obtain a resolution of 0.2 Practical Salinity Unit (PSU) for salinity and 0.25 mm for depth. But by employing the reflected amplitude, the resolution improves to 0.00119 PSU for salinity and 0.00273 mm for depth. The proposed approach allows for the transduction of two variables from a single transducing element without requiring any additional sensor structure modifications, and without compromising accuracy or sensitivity, and is expected to be a breakthrough in the development of a single multi-parameter fibre-optic sensor.

The following presents a comparison of an extrinsic Fabry–Perot interferometer (EFPI)-based temperature sensor, constructed using a novel diaphragm manufacturing technique, with a reference all-glass EFPI temperature sensor. The novel diaphragm was manufactured using polyvinyl alcohol (PVA). The novel sensor fabrication involved fusing a single-mode fibre (SMF) to a length of fused quartz capillary, which has an inner diameter of 132 μm and a 220 μm outer diameter. The capillary was subsequently polished until the distal face of the capillary extended approximately 60 μm beyond that of the single mode fibre. Upon completion of polishing, the assembly is immersed in a solution of PVA. Controlled extraction resulted in creation of a thin diaphragm while simultaneously applying a protective coating to the fusion point of the SMF and capillary. The EFPI sensor is subsequently sealed in a second fluid-filled capillary, thereby creating a novel temperature sensor structure. Both temperature sensors were placed in a thermogravimetric analyser and heated from an indicated 30 °C to 100 °C to qualitatively compare sensitivities. Initial results indicated that the novel manufacturing technique both expedited production and produces a more sensitive sensor when compared to an all-glass construction.