TOUCHSCREENS could soon start poking back at you. Vibrations that produce a force field beneath your finger could create the sensation of dips and hollows on flat tablet computers like the iPad.
Haptic technology 鈥� used to communicate through a user鈥檚 sense of touch 鈥� has already found its way into mobile devices, says , head of haptics at Northwestern University in Evanston, Illinois.
These devices tend to be quite basic, however, creating clicking sensations by vibrating the screen or even the entire device. A more sophisticated approach involves vibrating the screen in and out at ultrasonic frequencies, says Colgate. This means the amount of contact between the finger and the screen can be controlled and textures and edges can both be simulated by adjusting this friction, he says.
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The problem in these systems is that to get the desired effect your skin has to be moving over the surface. It won鈥檛 work if it鈥檚 stationary. Colgate鈥檚 solution was to superimpose lateral oscillations perpendicular to the vertical ones. 鈥淲e discovered that if our lateral vibration was at the same frequency as the ultrasonic vibration then you could push the finger,鈥� he says.
The result, besides allowing different textures and sensations to be created, is that the finger can be gently pushed across the surface so that it is coaxed into a particular position. The vibrations can be so slight the user barely notices them, but they stretch skin receptors in the user鈥檚 finger in the same way as if they were touching something with depth, fooling the senses into believing the surface is not flat. To the user it can feel like they are touching an indent in the screen, like the 鈥渉ome鈥� button on an iPhone, for example.
聯Skin receptors in the user鈥檚 finger are made to feel as if they are touching something with depth聰
Although the effect is still quite weak, this kind of technology has the potential to influence future touchscreens, says at the Institute of Intelligent Systems and Robotics at the Pierre and Marie Curie University in Paris, France.
Hayward tried out Colgate鈥檚 prototype at the World Haptics Conference in Istanbul, Turkey, in June. 鈥淚t feels like the surface is coming to life under your fingers,鈥� says Hayward. 鈥淎nd it creates the effect without having to move your finger.鈥� This is particularly useful in a small, cluttered screen, he says.
At the moment the prototype merely creates the effect on a piece of glass, vibrating it at 22 kilohertz with an amplitude of less than a micrometre. 鈥淏ut there鈥檚 no reason why we can鈥檛 make it work in a touchscreen,鈥� Hayward says.
