Thirty years ago the world marvelled at the science fiction of the Six Million Dollar Man. Today, although we are far from creating super-powered robotic limbs and organs, the likelihood of combining the biological with the electronic is greater than ever before.
Researchers at Nanyang Technological University in Singapore recently unveiled a tiny heart pump with a micro-engine, powered by a battery, which they claim is the smallest in the world.
According to cardiologists, standard heart pumps weigh over 1kg and require open-heart surgery, which can leave patients vulnerable to infections.
"The key advantage of this new heart pump is that it can be inserted without resorting to open-heart surgery, meaning that heart patients can avoid complications like immunological rejections and thrombotic infections," says Professor Freddy Boey, a key member of the research team.
Other researchers have had success developing chips that could soon be used to replace damaged nerve or brain tissue.
New Scientist Magazine reports that scientists have developed a chemical microchip that operates in a similar way to the brain`s normal, chemically-based signalling system, unlike existing chips, which are stimulated via electricity.
While existing devices - such as cochlear implants - have proven effective, they use electricity to stimulate the nerve cells directly, but this can only be done in an indiscriminate manner, whereas the new synapse chip uses a chemical signal in much the same way as genuine synapses do.
The researchers have been able to create four artificial synapses on a silicon chip of one centimetre squared. Each synapse is a tiny hole in the silicon, which is just 5 000 nanometres wide.
Even though this is much bigger than a real synapse, it can stimulate a single cell in a layer above the chip, because - when an electrical field is applied - a neurotransmitter stored in a special "pipeline" in the chip is pumped out to stimulate nearby cells.
"The amazing thing is that we estimate that 1 000 artificial synapses firing 1 000 times a second would need as little as half a millilitre of fluid to function for 250 years," says Mark Peterman, one of the research scientists.
He believes that the synapse chip could act more like the brain`s natural processes than the electrically charged chip, because it could allow for very sensitive and specific responses.
However, the researchers maintain that there are still many hurdles to be overcome, such as stopping the device becoming clogged with immune cells and replenishing its reservoir.
"The important thing is that this device could turn out to be an early forerunner of complex human-computer interfaces," says Peterman.
Elsewhere, US researchers are poised to carry out the first tests of a silicon chip designed to replace a damaged part of the brain.
The implant, which would stand in for the hippocampus, a part of the forebrain that is vital for storing long-term memories, could one day be used for people who face memory loss due to Alzheimer`s disease, epilepsy or a stroke.
The study has so far been conducted on the hippocampuses of laboratory rats, which were sliced up into sections and stimulated with electrical signals. This was done repeatedly until the researchers could be sure which electrical input produced a corresponding output.
By putting together the information from the various slices, they built up a mathematical model of the entire hippocampus, perceiving it as an array of neural circuits that work in parallel to process data.
The model was then transferred onto a chip, which communicates with the brain through two arrays of electrodes, placed on either side of the damaged area.
One set of electrodes detects the electrical activity coming in from the rest of the brain, while the other sends appropriate electrical instructions back out to the brain.
"While these developments bode well for the future of human/machine interaction, there is still a very long way to go before we truly reach a stage where machines can replace biological parts," says one of the developers.
"A good analogy would be the relationship of the early telegraph systems to the latest mobile phones."
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