Enabling technology

For people ‘locked in’ with conditions such as ALS, their only contact with the outside world is via sophisticated technology – such as eye-tracking systems that help them spell letters out one at a time. But at an advanced state of deterioration their eye muscles stop working – rendering the system useless. So scientists have begun to develop systems that bypass the senses and tap directly into the brain. A number of devices can now ‘read’ brainwaves, allowing ALS sufferers to communicate once again. The cost of these systems is often around $25,000 (£12,500) – far beyond the reach of most people. But one team of engineers has managed to develop such a system for just $5,000 (£2500). “The US Medicare system will reimburse up to $5,000 – so that was our aim,” says Mark Manasas, a project manager at Cambridge Consultants in the US. The device works by detecting an involuntary ‘surprise’ response called the P300 response – which produces a tiny voltage spike in the brain. On a viewing screen, letters are arranged into a grid, then each rows or column is lit up briefly “Every time ‘your’ letter flashes, there is a tiny P300 response which can be detected,” says Manasas. Removing so much cost from the system has meant many compromises – but accuracy has been maintained, says Manasas. The system uses EEG sensors to detect brainwaves, in the form of electrical impulses on the scalp. The sensors are embedded in a ‘cap’ worn by the patient. The skill is in amplifying the voltage spike into a meaningful digital signal. “We’ve looked at a number of amplifier configurations,” says Manasas. “To take this to the next level we would need to create an active electrode, which would give a better signal.” Future development depends on funding, and there are moves to try and set up a non-profit organisation to take it further. Possible areas of development include: using more sophisticated EEG sensors; and making the sensors semi-invasive by penetrating 50 microns into the skin – where conductivity is higher. Physical assistance From a low-cost brain scanner to high-cost prosthetics: several manufacturers believe that the market is ripe for sophisticated prosthetic limbs that are more responsive to the needs of the user. An example is the iLimb, a ‘bionic hand’ developed by Scottish company Touch Bionics. The company recently demonstrated the hand, which has five individually powered digits including jointed fingers and rotating thumb. A full commercial launch is expected within months. While its £2500 price tag is comparable with that of the brain-computer interface, this is still around twice the price of a conventional prosthetic device. Myoelectric sensors mounted on the skin collect muscle-generated electrical signals and feed them through to the hand, which is capable of three types of grip – precision, ‘key grip’ and power grip. One patient, who used the hand in a trial, recently used it to pick up a pint of beer for the first time in 30 years. The hand itself, made from high temperature nylon from DuPont, incorporates several motion components: a central controller; a carbon Kevlar drive belt, which provides grip force along the whole finger; a non back-drive gearbox, ensuring that a grip is fixed in position; and a motor in each individual finger. Meanwhile, Iceland-based Ossur has developed similar prostheses for the knee and foot. Its Proprio Foot – priced as high as £9000 – claims to be the world’s first motor-powered, intelligent prosthetic foot. A series of accelerometers sample the foot more than 1,000 times per second to determine its position in space. The angle of the ankle and toes are then adjusted using a set of actuators to ensure a more natural stride. For example, the toes are curled upwards as the leg swings forwards,