Development of In-Shoe Wearable Pressure Sensor Using an Android Application

Human footwear is not designed for relieving the pressure on the foot heel. The presented study aims to identify the correlation between the Vertical Ground Reaction Force (VGRF) and the Preferred Transition Speed (PTS). Furthermore, the phase of gait is classified with different subjects. An in-shoe wearable sensor along with the use of an Android application is implemented to find out the walking patterns and to collect the data driven on the Activities of Daily Living (ADL). The In-shoe sensor circuit is composed of the PIC16F688 microcontroller, the Bluetooth module, and the three Flexi-Force A201 sensors, which are placed at the heel contact (1st metatarsal, and 5th metatarsal). The statistical analysis is performed in order to discover the deformity of the foot. The outcomes with one subject show weak linear relations between the normal and the fast walk. In addition, a significant difference in the body weight acceptance between the normal and the slow walk. The T-test hypothesis is used with two healthy subjects using ∝=0.05. The results from this test show a significant difference in their peak pressures. In addition, no difference between their peak-to-peak time intervals. Preferred Transition Speed (PTS) versus Vertical Ground Reaction Force (VGRF) are measured with 19 subjects. The experiments' results demonstrate that VGRF is averagely increasing with 18.46% when the speed changes from 50% to 75% of PTS, while VGRF increases 21.24% when the speed changes from 75% to 100% of PTS. In final, Logistic regression between 12 healthy subjects demonstrates 82.6% accuracy between partial foot bearing and their normal walk.