Bionic Leg Prostheses Essay

Bionic leg prostheses are motor powered artificial limbs that are enabling amputees to pursue fully mobile lifestyles. Most of today’s leg prostheses are passive and require a lot of energy to use, this makes them more of a hindrance than a help on people’s lives. Conventional leg prostheses consist of spring structures that store and release elastic energy through each walking stance period and cannot generate more mechanical energy than that is stored during each step, this leads to 10-60% more required energy and 11-40% slower walking speeds (S. K. A, M. B, and H. M. H, 2008). On the contrary active bionic leg prostheses output a significant amount of energy to lift the person during movement, and are capable of adapting automatically to variation in walking velocities and terrain, much like the human leg.
Studies show that the inability of passive prostheses to produce positive work is the main cause of high metabolism and lack of balance when walking in amputees (S.
K. A, J. W, and H. W. H, 2009). With the current prosthetic technology, a bionic leg prosthesis such as that produced by MIT’s Bioomechatronics Group consists of three interfaces: a mechanical interface which deals with how the artificial limb is connected to the body, an electrical interface which is how the prosthesis communicates with the body, and a dynamic interface which deals with how the prosthesis functions during movement. The mechanical interface of bionic prostheses consists of artificial limbs that are attached to the body directly using a custom 3D printed synthetic skin, which are more comfortable than that of conventional artificial limbs that force the leg of the amputee to conform to a plastic socket. The synthetic skin shaft is developed to compensate with tissue, such that where the human tissue is soft the shaft is hard and vice versa. The electrical interface consists of electrodes that communicate with the nervous system to power and control
movement. The dynamic interface of the bionic limb consists of 3 computers programmed to analyze the complexity walking and react with no delay, sensors to detect speed and terrain, and a muscle tendon like motor system that offers power to lift a person. Although research in this field in heading in the right direction, today’s prosthetic technology is a long way from achieving fully functional limb replacements due to challenges such as significant bulkiness of bionic prostheses when compared to human limbs and discomfort.