Touchscreens used on smartphones, tablets and wearables are much better than similar technologies of a few decades ago, but there is still a long way to go, as researchers have demonstrated by take advantage of a screen protector covered in bumps to significantly reduce the latency of a modern touch screen.

As responsive as a touchscreen may seem, there’s actually a slight delay between when you tap on a screen and when a device’s UI responds to the gesture and updates the graphics to the touchscreen. ‘screen. It’s almost completely unnoticeable when you’re just performing quick taps, but becomes more evident with longer gestures like swipes. Grab an icon on your smartphone’s home screen and drag it quickly, and you’ll see its position on the screen behind where your fingertip actually is. The lag is also very noticeable when drawing or writing on a touchscreen using a stylus, which is why few devices come close to perfectly recreating the pen-on-paper experience that instantly leaves strokes behind. .

Touchscreen latency will improve over time (most smartphones today have a latency of around 80 milliseconds), but researchers at Future Interfaces Group at Carnegie Mellon University have come up with a smart shortcut to improve latency right now without changing a touchscreen’s hardware.

It starts with the addition of a plastic film over a touchscreen covered in a grid of small bumps measuring just five microns high. The bumps are invisible to the human eye and barely noticeable when a finger moves over the applied film, but like scratching a fingernail on one of those lenticular images that seem to move as you change your viewing angle, in dragging your fingertip or stylus over it. the bump pattern produces a subtle acoustic vibration that is often in the ultrasonic range outside of human hearing.

A user’s ears cannot hear the vibrations produced, but a microphone can, and researchers are able to capture the sounds produced and determine the speed and direction of a touchscreen interaction with a latency of ‘about 28 milliseconds. What they can’t determine from vibrations is where a finger or stylus actually makes contact with a touchscreen, so they use that acoustic data along with the more precise position data captured by the touchscreen. capacitive touchscreen itself to feed a machine learning model that can predict where a fingertip or stylus is moving, and update a device’s user interface to reflect that prediction.

This method isn’t always 100% accurate, but it’s accurate enough to make touchscreen devices much more responsive and responsive, with perceived latency reduced to just 16 milliseconds and distance errors reduced to around five millimeters. When it comes to a user, the device they’re using suddenly feels more vivid, and while moving around icons isn’t the most exciting application, this research could potentially significantly improve the simulated pen experience on paper, allowing artists and dedicated note takers to use their devices more naturally.