Wireless Multi-Axial Force Sensing Shoe for Gait Abnormalities Monitoring

Abstract

Measurements of sequential Ground Reaction Force (GRF) can provide quite useful information for monitoring of gait abnormalities during activities in daily life. Measuring sequential GRF in conventional approach using force plates is difficult due to the limited number of force plates. Therefore, we developed a fully untethered GRF sensing system having the low height (12 mm) and the capability of sensing simultaneously shear and normal GRF. The biaxial force sensing shoe showed the excellent repeatability (0.6 %) under long-term periodic loading condition for two hours. Comparison experiments with commercially available film type force sensors, FSR (Interlink) and Flexiforce (Tekscan), were performed under walking condition for twenty minutes. Owing to the high repeatability of the proposed system, variabilities of swing time and stance time of user were investigated with two subjects, a healthy subject and a foot-drop patient. We suggested three diagnostic measures in consideration of conventional approaches — variability for gait symmetry, center of pressure distribution for balance, and ratio of shear and normal GRFs for foot pronation.