An insole shear force monitoring system for optimum alignment in lower limb amputees

Lower limb alignment plays a crucial role in providing basic walking functionality in a natural manner as well as the appearance of the gait to amputees. Presents, amputee gait monitoring still remains largely in laboratory scale. There is an urgent need to monitor gait in outdoor activities. Anterior-Posterior (AP) shear force is the most sensitive parameter in prosthetic alignments. A force plate can measure the shear force but it is expensive and can only be available in a gait laboratory. To monitor gait outside the laboratory, a miniature, portable and wearable insole shear force monitoring system is proposed. The system can measure AP shear forces as the body load line sways anteriorly and posterioly. As weight is a crucial issue, light weight material is used for the sensor housing of the system. two arrays of force sensitive resistors (FSR) are used to measure the AP shear force as the load line sways. Two insole shear force sensors of the monitoring systems are designated to be bonded strongly underneath a shoe at the heel and the forefoot respectively. This paper presents the development of the monitoring system and initial test results.