Can you build a bionic body? The arm

Later this year a team of researchers will try out the first bionic eye implant in the UK hoping to help a blind patient see for the first time. It is one of the extraordinary medical breakthroughs in the field, which are extending life by years and providing near-natural movement for those who have lost limbs.

Over the coming weeks, BBC News will explore the field of bionics in a series of features. We start with a selection of the latest scientific developments. Here we look at the arm.

Injured soldiers returning from wars in Iraq and Afghanistan have fuelled bionics research in prosthetic limbs. A university in the US has developed one of the most advanced bionic arms with military funding. It has nearly as much dexterity as a natural arm, with independent finger movement.

It responds to the user's muscles that remain in their residual limb. Muscles generate small electrical signals when they contract, these can be detected by sensors placed on the surface of the skin. The bionic arm uses these, so that contracting different muscles produces specific movement, such as opening or closing a fist.

In the video Michael McLoughlin, from Johns Hopkins University's Applied Physics Laboratory, explains how the Modular Prosthetic Limb (MPL) works, while Air Force Tech Sgt Joe Delauriers practises using it.

One of the next steps is to work on using brain implants to control the arm, when residual muscle contraction is lost. Initial work with the MPL has used electrodes to tap into brain cell signals, allowing the patient to stroke his partner's hand with his robotic one.

The Bionic Bodies series on the BBC News website will be looking at how bionics can transform people's lives. We will meet a woman deciding whether to have her hand cut off for a bionic replacement and analyse the potential to take the technology even further, enhancing the body to superhuman levels.