A Study on the Pressure Sensor for Estimating the Load Point in a Prosthetic Socket

A transfemoral prosthesis is a device that performs locomotion in place of the amputated lower leg. It is necessary to change the locomotion style suitable for each environment in order to cope with the locomotion environment that changes discontinuously. To implement this, studies on the transfemoral prosthesis have been conducted in the direction of detecting the user intention to change locomotion through the biomechanical characteristics inside the socket in direct contact with the amputated section. Among the biomechanical features, the pressure change inside the socket enables the identification of a load point according to the intentional movement of the lower leg. Therefore, studies have been conducted to detect the user intention in locomotion by measuring the pressure change. However, previous studies have left the need for a sensor system suitable for the body flexion of the amputated section and the internal environment of the socket. Therefore, in this study, a pressure sensor that is not vulnerable to noise caused by body impedance, has a flexible film type, and can respond to the curved surface of the socket was fabricated. In this study, a pressure sensor was fabricated by applying Velostat film that satisfies the requirements of the sensor inside the socket, and a cutting method was considered to remove a unfastened problem due to uneven surfaces. The sensor proposed in this study will be able to be used to estimate the load point inside the socket by improving the problems of the existing pressure sensor system. In addition, it will be possible to apply it to a system that detects the user intention to change the prosthetic leg control through future studies.