A fiber SPR respiration monitoring device based on SF-LIBR composite film

Parameters such as respiratory rate and respiratory flow play a crucial role in evaluating human health. To ensure respiratory monitoring equipment can be used in various environments, it must be portable, wearable, and biocompatible. This study introduces a wearable surface plasmon resonance (SPR) humidity sensor that utilizes an SF-LiBr composite film to monitor respiration by detecting humidity changes. The refractive index of the SF-LiBr composite film varies with humidity levels, impacting the phase matching conditions of the SPR and enabling humidity detection. Experimental results demonstrate that the SF-22.1 wt % LiBr sensor has a wide sensing range of 35−99% relative humidity (RH) and can monitor different breathing states in real-time. This innovative sensor concept offers valuable insights for the advancement of wearable health monitoring devices.