Design of lower limb prosthesis for controlling contact pressure by MR fluid

Abstract

In case of a lower limb prosthesis, the most important parameter is the fitting between the cut section of the leg (stump) and the socket. It has been observed that the contact pressure between the socket and the stump changes after the alignment of the lower limb prosthesis changes and also during dynamic movement such as walking or running. The main aim of this research is to design a novel socket using smart materials, such as magneto-rheological (MR) fluid, which can transform the rigidity and capacity of the socket to accommodate the dynamic movement and alignment changes. In order to determine design parameters of the socket, we conducted various experiments such as subjective evaluation of pain by the contact pressure, measurement of the stiffness of the MR bag in which MR fluid was filled up. The MR socket was actually developed as a prototype based on the above experiments. The fitting between the stump and the socket was investigated subjectively and also based on the pressure sensors. The contact pressure and the pain felt by the amputee using a lower limb prosthesis have become smaller in the proposed MR socket, especially, on the patellar tendon. The proposed MR socket had a possibility to improve the fitting between the stump and the socket.