Wearable Ring-Shaped Fiber Bragg Grating Sensor for Finger Tapping and Pulse Wave Monitoring

Wearable sensors for neuromotor and cardiovascular parameters are increasingly relevant for unobtrusive assessment in clinical and out-of-clinic settings. In this work, a wearable ring-shaped sensor is proposed as a single-platform device conceived to support two monitoring modalities: finger tapping movement (FTM) assessment and cardiovascular pulse wave (CPW) dynamics acquisition. The ring sensor embeds an FBG within a mold cast elastomeric matrix and is designed to accommodate different finger sizes. Embedding enhances FBG sensitivity to externally applied pressure variations while providing mechanical protection, compliance, and thus wearability. Experiments on healthy volunteers provide a feasibility assessment of the dual operation of the proposed device, showing reliable tap-event detection across different FTM tasks and CPW acquisition during rest. The recorded signals are processed to identify tapping events and cardiac cycles, enabling the estimation of tapping rate and heart rate and the evaluation of the characteristic waveform morphology associated with both FTM and CPW. The proposed solution enables concurrent motor and cardiovascular monitoring using a single and streamlined optical-fiber based wearable.