A smart insole for monitoring plantar pressure based on the fiber Bragg grating sensing technique

The analysis of plantar pressure distribution is essential in the field of biomedical and sports-related applications. In this study, a smart insole was developed for the measurement of plantar pressure distribution and the evaluation of body postures using optical fiber Bragg grating (FBG) sensing technology. Four FBG sensors characterized by four different center Bragg wavelengths, 1528 ± 0.3, 1532 ± 0.3, 1535 ± 0.3 and 1539 ± 0.3 nm, were located at the first metatarsus, third metatarsus, fifth metatarsus and heel position, respectively. The measurement sensitivity of all the FBG sensors was 0.000412 nm/kPa, approximately. Silica gel material of modulus = 10 MPa was selected to incorporate the FBG sensors. All FBG sensors were multiplexed together with one optical fiber cable. The performance and functional properties of all FBG-based pressure sensors were calibrated in the laboratory to evaluate plantar pressure distribution. A male subject was selected for performing four tasks, namely standing in an...