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Technology has always strived to match the incredible sophistication of the human body. Now electronics and hi-tech materials are replacing whole limbs and organs in a merger of machine and man.
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.
Some help is possible
- 1. Small generator creates regular bursts of electricity
- 2. The bursts travel up a cable to the brain
- 3. Thin electrodes deliver the stimulation
The brain is the most complex organ in the body. When things go wrong, from dementia to depression or a stroke, the consequences can be debilitating.
However, stimulating small areas with electrical impulses can help patients. Thousands of people with incurable Parkinson's disease have been relieved of tremor, rigidity and slow movement in this way. A £30,000 ($48,000; 36,000 euros) operation to place electrodes deep inside the brain has enabled some wheelchair users to walk.
Other research, on rats, is focused on trying to replace damaged parts of the brain with microchips.
In clinical trials
- 1. Sensor detects sugar levels in the blood
- 2. Data sent to computer which calculates insulin dose
- 3. Insulin pumped into the blood
Failure to control sugar levels in the blood has deadly consequences and it's a challenge faced by hundred of thousands of people with Type 1 diabetes. Their pancreases cannot produce insulin, the hormone vital for sugar control.
Trials at Cambridge University in pregnant women with the condition have suggested that an artificial pancreas can help control sugar levels during pregnancy. This could save the mothers' life and improve the health of the baby.
The artificial pancreas uses sensors to constantly monitor the level of sugar in the blood. This information is fed to a computer program to work out the recommended insulin dose which is then injected into the bloodstream by a pump.
The bionic ear - or cochlear implant - is one of the most commonly used bionic body parts. It has returned some level of hearing to tens of thousands of people around the world.
Sounds create vibrations in the ear which are picked up by thousands of tiny hairs in the cochlea. The tiny movements are converted to electrical signals which are sent to the brain, but if the hairs are damaged it results in hearing loss.
Cochlear implants deliver electrical signals directly to the brain. A microphone is attached to the outside of the head and converts sounds to electrical signals. These pass down a thin wire which is threading into the cochlea. Electrodes at the end deliver the signal directly to the auditory nerve.
Each implant costs about £16,500 ($26,000; 20,000 euros) before the added expense of surgery and rehabilitation. Recently, patients have been fitted with a single implant which can restore hearing to both ears.
Fitted in more than 950 patients
Heart transplant waiting lists are long and some patients die before a suitable organ becomes available. Plastic hearts buy people time - the longest a patient has survived on one is three years.
The whole heart is replaced by two chambers, with valves that let blood in and out. A pump housed in a backpack pushes the blood to the heart along tubes that enter the body below the rib cage. Air is rhythmically pumped into the artificial heart, forcing out blood round the body in much the same way that a beating heart would.
Matthew Green was the first UK patient to go home with a Total Artificial Heart after an operation at Papworth Hospital in Cambridgeshire at the end of 2011. It was fitted on the NHS at a cost of about £100,000 ($160,000; 120,000 euros). Consultant cardiothoracic surgeon, Steven Tsui, explains how it works in the video.
Implants help restore sight
Later this year the first eye implant in the UK will take place. A light-sensitive chip will hopefully allow the patient to see with their damaged eye, unlike alternative approaches that use a camera fitted to a pair of glasses.
The light-sensitive chip is attached under the retina at the back of the eye. It converts light into electrical impulses which are then sent to the brain. The patient is then able to interpret the light falling onto the tiny 1,500 pixel implant as recognisable images. The implant costs about £65,000 ($100,000; 80,000 euros) excluding surgery and maintenance costs.
Clinical trials in Germany have restored sight to some patients who were completely blind due to retinal disease. They were able to read and see basic shapes after the chip was fitted.
Prof Robert MacLaren, will lead the trial at Oxford Eye Hospital, along with Tim Jackson at King's College Hospital. In the video Prof MacLaren demonstrates the Retina Implant.
One of the greatest challenges in bionics is to replicate skin - its ability to feel pressure, temperature and pain is incredibly difficult to reproduce.
Prof Ali Javey, from the University of California, Berkeley, is trying to develop an "e-skin" a material that "mechanically has the same properties as skin". He has already woven a web of complex electronics and pressure sensors into a plastic which can bend and stretch.
Getting those sensors to send data to a computer could give a sense of touch to robots. The dream is to fit e-skins to bionic limbs. However, he says it would be years before sufficient advances in electronics have been made to feed that information to the brain.
Mimics natural movement
Lighter hi-tech materials and technological advancements now mean that bionic legs are closely replicating natural movement.
One of the most sophisticated is the Genium, launched in the UK at the end of last year.
Seven sensors, including a gyroscope and an accelerometer - the same technologies used in a Wii remote control - detect the leg in a three-dimensional space. An on-board computer operates hydraulic valves which control the leg's movement. The leg can respond differently to walking backwards, climbing stairs and various walking speeds.
The cost of the leg, depending on patient need, is around £50,000 ($80,000; 60,000 euros). This includes all fitting, warranty and future servicing costs.
Geoffrey Harding, from Ottobock, the company behind the invention explains how it works in the video.
War injuries boost advances
Injured soldiers 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 and 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. Initial work with the MPL has used brain cell signals to enable a patient to stroke his partner's hand with his robotic one.
Production: James Gallagher, Tom Beal, Anna-Marie Lever. Design: Mark Bryson. Development: Luke Ward.
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. The series continues on Wednesday with a look at some of the earliest prosthetics from ancient Egypt.