Flexible Dynamic Pressure Sensor for Insole Based on Inverse Viscoelastic Model

The quantification of the plantar arch load and its surface distribution is essential to improve locomotion in many sports as well as rehabilitation protocols for patients. This paper has a threefold objective. First, it focuses on the design, fabrication and characterization of dynamic force sensors, based on both a single and multilayer of Velostat piezoresistive polymer. A matrix of 9 x 3 flexible pressure sensors has been developed to analyze and recognize plantar movements. Second, two models linking the plantar pressure to the resistance of the piezoresistive material, with and without taking into account the viscoelastic nature of the piezoresistive material, are proposed. Lastly, an inversion of the models is employed in order to estimate plantar pressure as a function of the variation in material resistance. An evaluation of the plantar pressure for various movements is also proposed.