Wearables based on fiber Bragg grating sensors for applications in Smart Healthcare: from design to test

Recently, the healthcare system has undergone a prospective transition by bringing patient-centeredness to the forefront. A lot of effort has been made to identify ways in which care could become more patient-centered and reach out into every corner of the community to adequately deal with the most significant phenomena of the 21st century: the increasing lifespan of the population and their more active lifestyle. Although people are living longer, they are not necessarily healthier than before. The Global Burden of Disease, a study conducted by the World Health Organization, predicts a very large increase in disability caused by age-related chronic diseases (e.g., cardiovascular diseases, stroke, and neurological diseases) which require long-term treatments and, in turn, cause a considerable economic burden on the healthcare management and the social insurance programs. In this context, a healthcare system that begins to look into smart technologies can promptly respond to these urgent health needs. The Smart Healthcare (SH) is an innovative way to provide care by allowing higher empowerment of patients, facing fragmentations in the health system, and fostering greater coordination and collaboration with organizations and providers across care settings. This approach relies on the use of a new generation of information technologies to transform the traditional medical system in an all-round way, making healthcare more efficient, more convenient, and more personalized. The present work positions itself within the stream of research on wearables based on fiber optics for SH framework and addresses the topic of developing medical wearables for clinical applications. Among several smart technologies, the attention mainly goes to wearable devices since they are already revolutionizing care delivery by enabling continuous, unobtrusive, and longitudinal health monitoring outside of the hospital. Wearables have evolved to become one of the biggest industries in the world: their market is expected to grow by 89 million by 2022, connecting over 900 million, confirming how these devices are becoming a life necessity. In a few words, wearables have paved their way into everything we use in our daily life. Usually, consumer wearables are made of electronic sensors but suffer from electromagnetic interferences, electrical safety issues (such as current leakage), and harsh conditions (such as high working temperature - T and pressure - P). These issues are dampening their usage as medical devices. This thesis proposes an innovative approach in the development of wearables for SH applications involving attractive optical alternatives based on fiber Bragg gratings (FBGs) due to their intrinsic advantages, among others, the immunity to electromagnetic interferences, the inherent electric safety, the high performance in terms of metrological properties, and the multiplexing ability. The remainder of this work is structured as follows: Chapter 1 presents the background of this work and establishes the context of the research topic. Chapter 2 proposes a description of the measuring principles of the FBG-based systems applied to medicine and healthcare and gives an overview of the state-of-the-art about the gratings employments in the development of wearables, innovative smart surgical tools, robotic devices, and biosensors. Chapter 3 includes a description of the physiological sources and how these signals can be transduced into physiological measurements. Attention will be mostly given to wearables for cardiorespiratory monitoring, joint motion detection, and sensorimotor behavioral assessment. Chapter 4 proposes the design, the fabrication, and the feasibility assessment of the FBG-based wearables developed during these three years of research. Chapter 5 discusses the main issues, challenges, and future trends of FBGs-based systems for SH applications.