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Biomimetic Design Enhances Ability to Heal

    Many people have pondered the possibility of prosthetics outperforming biological limbs, and many have looked at prosthetic limbs as an "unfair advantage." However, these bionic limbs are only mimicking what flesh and bone limbs can do.

     Biomimetic prosthetic design enhances an amputee's ability to heal and rehabilitate.

    At 17, the future head of the Biomechatronics research group at MIT Media Lab got trapped in a blizzard while ice-climbing the daunting Huntington Ravine on Mount Washington. He eventually lost both his legs to frostbite and gangrene.

    But a year after his amputation, Hugh Herr discovered that his climbing skills improved when he used his homemade prosthetic legs. He was able to climb walls that no one has ever mounted before. In an interview for the documentary Cyborg Nation, Herr recalled some of his colleagues threatened to cut their legs to have the same "unfair advantage."

    Herr was featured in the first episode of the documentary series. In the episode, he explained the power of biomimetic design, which he discovered as a young man who tinkered, designed, and climbed with his DIY prosthetic legs. Herr repeated the same process of whittling, machining, and carving until he got his prosthetic legs right. 

    Herr understood the power of biomimetic design for prosthetics. The biomimetic design approach creates solutions to human challenges by emulating designs and ideas already found in nature. Most modern, active prostheses are designed this way, unlike passive prostheses, which require the individual to use about 20% more energy when walking.

    Herr's bionic limb is designed to mirror how a biological leg and ankle work. Biomechatronics' key strategy is to look to nature when designing prosthetic limbs. To create an intuitive prosthesis, Herr and his team study how the calf muscle works and how the spinal cord controls this muscle using neural reflexes, for example. Sensors located under the bionic limb's shell facilitate neural reflexes, so a prosthetic user can make their prosthesis move using thought. 

    Biomechatronics' sensor-loaded legs also make it easier for the user to navigate different terrains and adapt to varying speeds—helpful when the prosthetic user needs to deal with ramps or stairs.

    Herr's philosophy lies in respecting biophysics. Amputees who use one of their prostheses are often surprised that they don't need further training because their bodies remember how to walk, and bionic legs are equipped with features that allow it to respond to the body as a biological limb would.

    Biomechatronics built its first foot and ankle in 2002. Since then, they have gone through 30 distinct designs that led to today's bionic limb.

    The group is continuously refining the bionic limb until prosthetic limbs can be a part of the human body—not dragging it down but healing and even enhancing its natural abilities.