A DEVICE that pinches and stretches the skin on the fingertips, rather than prodding and poking it, could revolutionise the way blind people access graphs and maps.
Current electronic Braille displays work by raising and lowering an array of pins to form individual characters. But the actuators needed to move the pins up and down are bulky because they need to be powerful enough to resist the pressure exerted by the finger. The size of the these actuators means that only 16 pins can fit into a square centimetre, severely limiting a display鈥檚 ability to represent images.
Now a team from Canada has improved this resolution, allowing tactile chips to display detailed maps, graphs and diagrams. It has designed an array of pins that move horizontally rather than vertically, when a voltage is applied. This movement stretches or pinches the skin.
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Fingertips are highly sensitive to this sensation. 鈥淚t fools the brain into thinking you鈥檙e touching a raised surface,鈥� says Vincent Hayward, who worked on the device with colleagues at McGill University in Montreal and the University of Montreal. These pins are not pushing against the finger, so the actuators can be made smaller.
鈥淚t fools the brain into thinking you鈥檙e touching a raised surface鈥�
The device, called the Tactograph, consists of a chip roughly 1 centimetre square with an 8-by-8 array of pins on top, mounted on a larger platform. First, a teacher digitally scans a picture, removes any text and highlights important boundaries using the Tactograph鈥檚 software. Then, as the user slides the chip across the platform with their fingertip, the pins move to produce the texture corresponding to the different parts of the image.
For example, when representing a map, the device would produce a vibrating sensation to mark out the borders of countries, and it would 鈥渃olour鈥� the interior of each region with a different static texture. The team demonstrated how the device has been used to display graphs, maps and diagrams at the ASSETS 2008 conference in Halifax, Nova Scotia, Canada, last week.
Stephen Brewster at the University of Glasgow, UK, believes the device is a big improvement on previous technology. He hopes it could even be modified to allow students to construct their own graphs and diagrams.
