Just wait until Paralympian Oscar Pistorius gets his hands on this: A team of mechanical engineers has created an prosthetic leg that is powered by a special type of liquid fuel called a monopropellant — the same kind of fuel that gives rockets their thrust. The new device could usher in the next generation of prosthetics — powerful and light-weight artificial limbs that will look and function more like the real thing.
Somewhat surprisingly, the human ankle supplies more energy to the process of walking than both the hip and the knee. Yet most standard below-knee artificial limbs do not produce sufficient power to support an amputee's walk. And indeed, today's devices only dissipate energy, or store and reuse energy in walking. This means that amputees have to put greater stress on their joints and expend more energy when they try to walk or run.
Looking to change this, UoA's Xiangrong Shen, along with researchers from the Georgia Institute of Technology, has developed a prosthetic limb that uses monopropellant — an energy-storing medium that decomposes upon contact with certain catalysts (monopropellants don't need to be mixed with other gases to be used as fuel). The resulting energy allows for the powering of a light-weight artificial leg that can be used on a regular basis.
In conjunction with this, Shen has also developed a sleeve muscle actuator, what is an artificial muscle that replaces the motor used in some alternative prostheses. But unlike other prosthetic actuators, Shen's sleeve muscle is more powerful, lighter, more compact — and its elastic properties make it more like a real biological skeletal muscle.
The next step for the researchers will be to ensure safety and reliability of the device, and to explore new ways of dealing with fuel storage, exhaust management (I wonder if it has a muffler), thermal insulation, and heat management. They're also hoping to make the device look and function just like a regular human leg.
But given that they've essentially created a rocket fuel-powered leg, it's not a stretch to suggest that future iterations will be significantly stronger and more robust than the real thing.
Image: University of Alabama.