Abstract
Continuous monitoring of respiratory activity is a key technology for early diagnosis of sleep disorder diseases and other diseases such as asthma. Coherence of respiratory regularity is a significant indicator for mental stress assessment and physical fitness evaluation. A PVDF film is one of suitable material for wearable respiratory sound sensor because it is flexible and sensitive to low frequency sound. Furthermore, a curved structure of PVDF film was reported to have higher sensitivity. We have investigated sensitivities of the curved structure of PVDF film by FEM analysis, and also compared experimental results with the analysis results. Our previous research showed that the curvature of 9 deg. with doubly fixed clamped condition had higher sensitivity than other conditions in the experiments. However, it was also suggested that the clamping conditions in the experiments were not ideal and thus the sensitivity improvement was not obtained so much as those by simulation. In this research, we introduced a new boundary condition model considering clamping state in experiments to simulate sensitivities of PVDF sensors of multi-curved structure, and also fabricated wearable respiratory sound sensors of multi-curved structure. Simulation and experimental results showed that sensors of multi-curved structure have higher sensitivity than flat sensor.
