Development of a Lower Extremity Rehabilitation Aid Utilizing an Insole-Integrated Load Sensor Matrix and a Sole-Embedded Measurement Node

Following an individual exercise program after a hip or a knee operation is crucially important as it enables the muscles of the operated leg to regain their strength and thereby support the recovery of the operated joint. Usually the patients have no assisting devices at home to help determine how much weight they put on the operated leg. Training with a scale helps, but in general, humans can not accurately estimate the amount of weight they put on the leg. To address this problem we have designed a lower extremity rehabilitation aid, which utilizes an insole-integrated capacitive load sensor matrix and a sole-embedded read-out electronics with wireless communication link. In this paper we present in detail the manufacturing process of the insole sensor. The placement of the electrodes, calibration, and user interfaces are also discussed. The system is found to be suitable for detecting too light and too heavy steps.