Ultrasound illusion could make buttons on a touchscreen feel real

Momentarily removing your finger from a glass plate and ultrasound can make it feel like you’ve pressed a button, which could be useful in virtual reality and new kinds of displays.

To Alex Wilkins

The illusion of pressing a button when you touch a flat surface using ultrasound can be used to add an extra dimension to touchscreen devices.

When you press the button with your finger, the friction causes the skin to stretch, and when you release the button, the friction decreases and the skin relaxes. Exploiting this effect by using ultrasound to abruptly change the friction of a surface can change the feel of an object, but how this happens or how reliably this effect is produced? It was unclear whether

Now Michael Wieltrowski and his colleagues at the Delft University of Technology in the Netherlands have created a glass plate that can change friction quickly. It does this with an actuator that emits ultrasonic waves to vibrate the plate.

The researchers mounted a camera under the plate to see what happened when people pushed the glass, and used ultrasound to influence its progression. “When I saw the images, I realized that there was stress. [in the form of] It’s the elastic energy that the skin stores when you push an object, and we can release that energy,” says Wiertewski. “That release feels like the object is actually moving.”

The ultrasound mimics the sensation of pressing and releasing a button, temporarily levitating your fingers to reduce friction and relax your skin.

The team tested how this effect worked on 12 people and found that if friction was reduced by ultrasound with a wavelength of 2 micrometers or longer, they were 75% more likely to feel a button press. discovered. “We have a better understanding of how to design these virtual buttons,” he says.

Ultrasonic vibration works using a thin glass screen that can be added as another layer on top of an existing screen, but more testing is needed first, he says. In people with very tough skin, the effect seems less noticeable, he says.

The technology, which harnesses ultrasound, could be very useful for virtual reality and new kinds of touchscreen displays, says Patrick Haggard of University College London. “One of the problems with touchscreens, he said, is that you can’t know what you’re doing without actually looking at it, but if you can engineer the feel of pressing certain keys, you can tell what you’re doing. You may feel it.”