ETRI's Clever Film Converts Light Into Detailed, Location-Sensitive Haptic Feedback
Low-cost film could provide detailed, location-sensitive haptic feedback for touch display devices — with increased vibration strength.
Researchers from Korea's Electronics and Telecommunications Research Institute (ETRI) have published a paper detailing a light-driven haptic film which, they claim, could allow future smartphones to provide feedback on the texture of displayed objects.
Putting haptic feedback into devices is nothing new, but the state of the art isn't too detailed: The majority of haptic feedback systems rely on a single vibration motor — meaning that the whole device vibrates regardless of where the feedback is supposedly triggered.
The ETRI team's solution to the problem: A film which converts light into vibrations, combined with a 3x3 LED matrix - and when put together the system allows the vibration to follow a triggering finger, creating the illusion of texture and movement.
The trick is in the film's conductive polymer coating, which absorbs near-infrared light and converts it into thermal energy. As the thermal energy enters the film, it causes bending — and as it cools, the film straightens again. Repeatedly rapidly enough, this movement comes across as vibration — providing the haptic feedback.
The researchers claim that the technology would be easy to implement in displays at any scale, and suggest a range of possible applications: Adding feedback to on-display dials, buttons, and sliders for vehicular user interfaces, supplementing Braille displays, and assisting with accessibility, as well as allowing smartphone users to "feel" the texture of an object on the display.
"The technology is expected to be used widely to support people who are vulnerable with information," ETRI's Shin Hyung-cheol says, "such as the visually challenged, by practically applying the original technology designed to deliver information through tactile sensation."
The team is now working to increase the strength of the vibrations, which are not currently powerful enough to be felt directly, by boosting the efficiency of the photothermal layer and in reducing the electricity consumption of the system in order to ease commercialization.
The team's work has been published under closed-access terms in the journal ACS Applied Materials & Interfaces.