Researchers in the United States have developed a wireless interface designed to enable paralysed people or those with reduced mobility to control computers, wheelchairs and other equipment with their thoughts.
The BrainGate project, being carried out by a consortium based at Brown University in the United States, began just over ten years ago by demonstrating that implants in the brains of paralysed people could allow them to use their thoughts to control objects around them. As l’Atelier reported in an article in 2004, the implant, which was connected to computers via a cable, detected the electrical signals emitted by neurons in the brain and then translated the person’s desire to make a movement into physical action. However these experiments soon came up against limitations, as none of the systems could be used under ‘normal’ conditions outside the laboratory setting. Patients could only use the prosthetic correctly when aided by a crew of lab assistants. “Using this in the home setting is inconceivable or impractical when you’re tethered to a bunch of electronics,” pointed out Brown University Engineering Professor Arto Nurmikko. It has taken ten years for the researchers, in partnership with Utah-based company Blackrock Microsystems, to develop a device about the size of a car’s fuel tank cap, which is attached to the skull and wired to electrodes inside the brain, thus avoiding the need for external cables as it processes the brain data.
Extracting a huge mass of data
The device contains a processor to amplify the electrical signals from the brain, circuits to digitise the information, and a radio to beam the information across to a receiver. The battery-powered device transmits data out of the brain at a rate of 48 megabits per second – about as fast as the average household Internet connection – consuming just 30 milliwatts of power. The electrodes in the pioneering implant can collect the activity of 100 neurons simultaneously and the implant can transmit the equivalent of about 200 DVDs worth of data per day. Although some similar devices have already been developed, Professor Cindy Chestek, Assistant Professor of Biomedical Engineering at the University of Michigan in the US, underlines: "There’s just no such thing as a device that has this many inputs and spits out megabits and megabits of data. It’s fundamentally a new kind of device.” Moreover, the brain signals can now be translated sufficiently precisely to understand what kind of movement the handicapped person wishes to execute. Ongoing tests on primates plus half a dozen human patients show that it is now quite feasible to use the power of thought to control a computer mouse or a robotic arm.
However, such devices still expose patients to too much risk for them to be used in a home environment. “That wire going through the skin is the most dangerous part of the system,” says Cindy Chestek, as it may cause an infection. In addition, the cost could still prove a substantial barrier, although the cost of electroencephalography (EEG) has fallen fast recently. Low-cost headsets now allow people to use thought to control their wheelchairs. Nevertheless, implant devices are still far from being perfected, and need to be far more powerful if they are to work accurately and become fully reliable.