Fabrication of high sensitivity flexible fiber Bragg gratings pressure sensors for comprehensive plantar pressure monitoring

In recent years, the development of wearable sensing devices has accelerated due to increasing demands for real-time, intelligent health monitoring. Fiber Bragg grating (FBG) sensors have emerged as a focal area of research, offering benefits such as distributed sensing, immunity to electromagnetic interference, compact size, and high safety during operation. Monitoring of plantar pressure is a crucial metric for evaluating foot health and analyzing gait. The data characteristics captured by smart insoles in plantar pressure monitoring are instrumental for diagnosing and assessing rehabilitation in motor and neurological disorders. This study introduces a flexible FBG pressure sensor featuring a microstructure, which exhibits high sensitivity (13.370 pm/kPa), minimal hysteresis (1%), and excellent repeatability and linearity across a pressure range of 0-40 kPa. The sensor has been integrated into a fabric shaped like an insole to detect plantar pressure distribution in various postures, including static standing, sitting, arm extension, stepping, and squatting.