Building the bionic man

Professor Sethu Vijayakumar currently has three arms.

A modified version of the i-Limb artificial hand is strapped to his left forearm; around his right arm is a band of sensors that detects the biosignals given off by the movement of his arm muscles. As those muscles contract and relax, the hand opens and closes.

In 2007, Edinburgh firm Touch Bionics created the i-Limb, the first powered prosthetic hand with articulating fingers.

We’re now attaching artificial sensors to the fingertips

Four years on and it’s evolving rapidly, part of a growing trend to augment the body, either to replace lost functionality caused by injury or illness, or merely to enhance human inadequacies.

Out on a limb

Vijayakumar is director of the Institute of Perception, Action and Behaviour (IPAB) at the University of Edinburgh, which has been working in conjunction with Touch Bionics on the i-Limb.

His research focuses mainly on improving the manual control and sensory feedback of the hand, aims that should make it more useful for amputees in scenarios where being able to sense the strength of a grip can be vital to avoid breaking a glass or painful handshakes.

“Instead of only an open/closed signal, we’re now looking at how finer control can be achieved with a pulsed signal,” Vijayakumar says. “If you make contact with an object, then you switch to a pulse mode.

This can be used to detect loads and optimise grip to reduce fatigue.

The latest techniques are taking humans into new territory, where artificial limbs are actually more functional than the original body parts they replaced

“In addition, we’re now attaching artificial sensors to the fingertips. You take that information and then feed it back through the electronics. Current research focuses on different modes of encoding that information. One way is by having a line of vibrating motors attached to a viable part of your skin. You have to train, and over time you learn to associate a particular force with a particular motor that vibrates. As you increase the grip force, the vibrations will travel further down the arm.”

Using technology to enhance the human body is nothing new – amputees have relied on prosthetics for generations.

Yet the latest techniques are taking humans into new territory, where artificial limbs are actually more functional than the original body parts they replaced. Human enhancement – based in this case on a combination of robotics, sensors and artificial intelligence – is increasingly enabling the body to exceed its usual aptitudes.

Although most emerging technologies remain remedial, scientists foresee a future where enhancements are no more extraordinary than a trip to the opticians.

Marrying man and machine

The marriage of man and machine isn’t always harmonious – when it comes to a permanent unison, there are serious commitment issues. Once a transplant or implant is in place, it’s there for the long haul, with potentially costly and painful procedures required to divorce technology from human.

The i-Limb ingeniously works around the problem of merging the natural and the artificial by keeping them technically separate, but training the human body to communicate with the device and programming the bionic arm to understand.

However, this only works if the body can communicate in the first place. Certain diseases, such as Parkinson’s and motor neurone disease, affect the neural connections between the body and the brain in a way that a non-invasive prosthetic such as the i-Limb simply can’t overcome. For conditions such as these, a direct approach is required.

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