Julian Smith has penned an excellent overview of prosthetic technologies for New Scientist. Smith describes the current state-of-the-union as far as assistive devices goes and looks at the potential for these devices to not just mimic normal human functioning, but to surpass it as well.
Smith writes,
After decades of amputees having to make do with designs that had changed little since the second world war, artificial limbs that predict their user’s every movement and look like the real thing are finally breaking out of the lab. Yet convincing and comfortable synthetic limbs like McNaughton’s are only the beginning of the bionic age.
Emerging prosthetic technologies promise not only greater power and flexibility but also pressure-sensitive artificial skin, and even limbs that are bonded to the body and controlled by the mind - and much of this within five years. Rebuilding amputees to be faster and stronger than before is rapidly becoming a realistic possibility. With experimental prosthetics increasingly able to integrate with flesh, bone and the nervous system, the very idea of “losing a limb” may one day become obsolete.
Examples of these cutting edge devices include the C-Leg from German orthopaedic company Otto Block and the Rheo Knee from the Icelandic company Össur, both of which use a combination of hydraulics and motors to make carrying the leg less tiring, plus carbon fibre to mimic the elastic properties of bones and tendons. As for arms, the smallest and most powerful yet is the i-Limb from British company Touch Bionics in Livingston, West Lothian. The i-Limb is a lightweight plastic hand in which each digit contains its own motor and can move independently in response to signals from two sensors attached to skin elsewhere on the user’s body.
There are even devices that are able to mimic the sense of touch, what’s known as ‘artificial skin.’ This is a rather complicated technical feat, but solutions have been proposed that involve a nanotube layer that measures changing resistance.
Of course, the ultimate next step is in directly connecting artificial limbs to the nervous system. This would require the tapping of brain signals, decoding them in real time and routing them to the prosthetic. Sensory input would then have to be relayed back from the prosthetic to the central nervous system. The New Scientist article goes over a number of ways this can be accomplished, including targeted muscle reinnervation.
The article also addresses the issue as it pertains to human augmentation:
With brain control seemingly not far off, prosthetic limbs could eventually be as easy to control as they are strong and light. They would then be stronger and faster than the real thing. So what happens when they surpass the limbs we were born with, and a prosthetic becomes an augmentation?
This issue hit the headlines in the case of South African sprinter Oscar Pistorius, a double amputee who runs on curved carbon-fibre “blades” and narrowly missed qualifying for the Beijing Olympics. Sports officials had earlier argued that his prosthetic feet gave him an unfair biomechanical advantage…
David Gow, inventor of the i-Limb hand, believes that artificial limbs may well give natural ones a run for their money, not just by being stronger and faster, but more aesthetically pleasing too. “Then we will have to evolve as a society a new morality, new ethics and codes of conduct, won’t we?” says Gow.
Read the entire article.
For more on this topic, read my article, “Is the world ready for cyborg athletes?”
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