Design and Fabrication of a Flexible Pressure-Sensitive Insole Based on Barometric Tactile Sensors

Plantar pressure measurement plays an important role in gait analysis which is a multidisciplinary field of study in medicine, rehabilitation, sports and robotics. The design and fabrication procedure of a novel pressure-sensitive shoe insole instrument is described in this study. The usage of this instrument is in sensing and real-time monitoring of the force pattern applied to the foot during gait. This system consists of a flexible circuit board with ten soft force sensing elements mounted on it, a custom data pre-process unit, a wireless transmission unit and a software for data monitoring. The soft force sensing components are designed based on barometer sensors covered by silicone layer in a specified shape to obtain about 300N supportable force range applied on each element. In order to evaluate the reliability and effectiveness of the proposed system, a healthy subject executed some preliminary tests during both static and dynamic activities. Conforming to the primitive results, the insole platform presented a rapid and accurate response in measurement of reaction force during different experimental attitudes. Thereupon, the fabricated insole is comfortable to wear, lightweight enough to use in daily activities simultaneously and it is a feasible instrument for plantar pressure mapping. Moreover, variety of parameters could be obtained by processes on the collected data and be used in related studies such as activity recognition or gait disorder detection.