Design of Piezoelectric based Pressure Sensors for Gait Rehabilitations using D33 Mode Polarization

Abstract

Gait Rehabilitation or gait training is a process of learn how to walk, either child or recovering after injury or stroke. Physiotherapist will used traditional therapy or robot assisted to train the patient. One of the sensor in gait rehabilitation is pressure sensor. It is to monitor the gait behaviour of the system in output voltage. The current pressure sensor attached to gait rehabilitation system is expensive, furthermore the sensing is low sensitivity and high noise. Piezoelectric materials are widely used as sensing element in a pressure sensor. But the current pressure sensor based piezoelectric is low sensitivity. The current design is based on d31 mode polarization where the electric polarized in thickness direction. The new design is designed based d33 mode polarization, where the electric will polarized between two conductors or polarized laterally. The piezoelectric pressure sensor based d33 mode polarization method is successfully fabricated. The d33 mode design is presented on printed circuit board(PCB) design, where the two conductors were placed on single sided PCB. The sensing element, Polyvinylidene fluoride or polyvinylidene difluoride (PVDF) is used as piezoelectric material in pressure sensor. Two designs are presented in this paper, first, the positive conductor with diameter 15 mm and second, the positive conductor with diameter 20 mm. These two designs were tested for load testing and strength test. From load test result, the design with diameter 15 mm is suitable for pressure sensor and design for diameter 20 mm is suitable for gait rehabilitation system. This paper is successfully presented the design of piezoelectric pressure sensor based on d33 mode polarization, fabrication of pressure sensor, and the experimental setup. The new design piezoelectric pressure sensor based d33 mode polarization method for gait rehabilitation is successfully implemented in gait rehabilitation system.