Design, development and characterization of a 3D printed wearable Fiber Bragg Grating sensor for cardiorespiratory monitoring using radial pulse waveform

In recent years, the advent of personalized healthcare has resulted in the need for wearable sensing technologies, which provide real-time monitoring of vital signs such as heart rate and respiratory rate. In particular, optical sensors based on Fiber Bragg Gratings (FBGs) have attracted significant attention due to their unique advantages over the conventional sensing methods, such as immunity to electromagnetic interference, compact size, biocompatibility, and good metrological properties. Embedding a Fiber Bragg Grating (FBG) in flexible substrates improves sensing performance and widens its scope for wearable sensing in healthcare applications. In this study, we report the development of a novel 3D-printed wearable FBG sensor using thermoplastic polyurethane (TPU), a flexible polymer with suitable properties for wearable applications. The pulsatile variation at the radial artery allows the sensor to monitor the arterial pulse waveform, from which vital parameters are subsequently measured using a suitable algorithm. The encapsulation of FBG improves the sensor’s dynamic response and makes it sensitive to the radial pulse. We initially evaluate the metrological properties of the embedded sensor to study the influence of external perturbations such as strain, temperature, and force. Further, the sensor is made wearable with an elastic Velcro band, following which the preparatory tests are performed on healthy volunteers across different age groups to evaluate its feasibility for real-time cardiorespiratory monitoring. The experimental findings suggest that the sensor exhibits improved sensing capabilities and highlight the potential of TPU-based wearable FBG sensors for continuous, real-time monitoring of vital signs in clinical settings with improved user comfort.