Optical sensors for cultural heritage and biomedical applications

The current Ph.D. thesis is articulated in 4 different research paths. The main research topic is on the fiber Bragg grating (FBG) sensor and its applications, mainly related to the conservation of the original status of the artworks. The second topic is related to the development of a new methodology for measuring the cracking of the Structural Health Monitoring (SHM) of cultural heritage. In the third topic, it is addressed the subject on the complex diatribe related to the risk in delivering anesthesia; field in which I have been also working, being a Biomedical Engineer. Finally, in the last topic it is proposed a biomechanics study on the patellar taping with the purpose of finding a correlation between the taping and a neuromuscular response. A new era of pollution requires an important focus on the conservation of archaeological sites and monuments. In the last years, great efforts were made to develop various sensors for different tasks; the FBG was one of the most studied thanks to the multitude of applications and the surprising performances. An original fiber optic sensor that combines the fiber Bragg gratings with a pH responsive polymer coating for monitoring the pH of the rains on critical and prestigious monuments is proposed. In this study, the arrangement setup of the optical sensor is modeled with Comsol Multiphysics (Wave Optics Module), based on the FEM (Finite Element Method) solver. Monitoring the pH of the rain can be used by experts to predict and control the corrosion of specific materials, especially limestone and marble, thus scheduling timely restoration. This also depends on the materials under analysis and it can have an important impact in terms of cost reductions and higher maintenance efficiency. In conclusion, the swelling response of hydrogels to the change of surrounding pH allowed the development of a model of hydrogel coated FBG pH sensor. Modelling the FBG pH sensor for monitoring the rain in archaeology and in cultural heritage provided innovative results in terms of high sensitivity and small dimensions of the device, allowing better intervention planning. In the first chapter, a preliminary study regarding the optical ring resonator is conducted because, ultimately, the goal is to realize a sensor that combines the FBG and the ring resonator for future developments in order to improve the sensor performances. Along with the development of the FBG sensor, a new methodology for measuring the cracking for the Structural Health Monitoring (SHM) of cultural heritage is also studied. The methodology is characterized by being minimally invasive on the artefact that has to be preserved, which is one of the main qualities required in this field. The approach is to determine the relative distance between two optical tags, using advanced fitting algorithms for the objective function. Different kinds of objective-function were taken into account in order to identify the best configuration to determine the fitting parameters, useful to the SHM. The optical tags are introduced for this scope; they are nothing but adhesive labels with appropriate images, through which, by using advanced fitting methods and algorithms, it is possible to determine the absolute and relative position and three-dimensional rotations of the images. The third chapter of this thesis deals with the risk and perception of risk in delivering anesthesia. The study examines the different perceptions of risk associated with anesthesia systems from the viewpoints of the product manufacturer and the caregiver. Only little research has been done on the impact of the perception of risk for patient safety in anesthesia. The role of the manufacturer in mitigating the perception of risk is central in the work. The risk was examined as the probability of negative occurrences based on the Medical Device Reportable (MDR) events and these risks were compared to how the caregiver perceives and manages them when delivering anesthesia. Analysis of the manufacturer’s public Medical Device Reportable (MDR) events data was performed in the US market and it represents the actual risk achieved; the bibliographic review provided a perspective on how the risk is perceived and managed by the caregiver when delivering anesthesia. The goal of the research path is to highlight how the role of the manufacturers can have an impact on the reduction of perception of risk in anesthesia, increasing patient safety. Finally, a biomechanical proposal on the estimation of Centre of Mass (CoM) trajectory has been developed. Motion capture systems and force platforms are still considered the gold standard for the estimation of accurate CoM measurements. In the last decade, several methods based on inertial sensors systems have been proposed based on double integration of acceleration signals of pelvis-worn sensors (M. J. Floor-Westerdijk, 2012). Although the portability of those methodologies is higher, drift errors due to extremely lengthy time acquisitions affect measurements, limiting their use. For the purpose of avoiding drift error and providing an accurate tool for ambulatory and/or home CoM assessment, the accuracy of a novel method based on a Biomechanical Model (BM) will be investigated. Among the large number of potential applications, this novel approach could be used in the identification of the effects of the patellar taping on neuromuscular control. More specifically, the patellar taping technique proposed by McConnell (J. McCONNELL, 1986) allows patients to engage in pain-free physical therapy exercises, by medializing the patella. Although this technique has been demonstrated to reduce the perceived pain of patients with patellofemoral pain syndrome and improve neuromuscular activity (N. Aminaka and P. A. Gribble, 2008), a deeper investigation on how patellar tape influences postural stability thought CoM assessment could be of great interest in the long term management of Chondromalacia Patellae. It has been demonstrated, in fact, that patellar taping affects knee proprioception other than relieving pain in subjects with patellofemoral pain syndrome (M. J. Callaghan, 2008). The aim of this research program is to pursue through static and dynamic tasks performed twice both by healthy subjects and not-healthy ones, with and without patellar tape.