Canadian researchers develop nano-sensors for smartphone display glass

Polytechnique Montréal scientist employ 3D laser-etched waveguides in Gorilla glass for novel sensor-based applications.

0 October 1, 2014
Mike McLeod

Polytechnique Montréal technique uses an infrared laser to etch a transparent waveguide for a photonic device in a smart phone screen. (Photo source: Polytechnique Montréal)

Polytechnique Montréal technique uses an infrared laser to etch a transparent waveguide for a photonic device in a smart phone screen. (Photo source: Polytechnique Montréal)

Researchers at Polytechnique Montréal say they have created 3D laser-written light-guiding systems, etched into a smartphone’s protective glass, that could one day be used for sensing everything from temperature to blood sugar levels.

“We’re opening Pandora’s box at the moment,” says Raman Kashyap, professor of electrical engineering and engineering physics at Polytechnique Montréal. “Now that this technique is viable, what remains is to invent new uses for it. This is why we are actively looking to partner with industry to develop this technology.”

To create these nano-sized, transparent systems, the research team used an infrared laser to etch three-axis transparent light pathways, or waveguides, within Corning Gorilla Glass, a strong, dense glass currently used in most smartphones. Measuring only a few microns in diameter, but up to a meter long, the channels are imperceptible to the naked eye but act as conduits for the light given off by the smartphone display. By analyzing shifts in the light allows for novel sensor applications.

As a proof of concept, the research team created a heat sensor composed of two waveguides, one straight and one curved. As the glass heats up and expands, the waveguides lengthen. By measuring how the light that emerges from one waveguide interferes with light from the other, the device can measure the temperature of anything it touches.

The team also created a smartphone authentication system by employing waveguides with patterns of tiny holes. Using this method, each smartphone could have a unique photonic fingerprint to add another layer of security in, for example, financial transactions.

“It’s easy to imagine how the technology could also eventually allow computing devices to be embedded into any glass surface, such as windows, tabletops, telephone screens, creating totally transparent tactile surfaces,” says Jérôme Lapointe, lead researcher and doctoral student at Polytechnique Montréal. “It would be like adding a new dimension to the real world that our eyes can see.”

For a complete explanation of the Polytechnique Montréal technique, the team’s work is detailed in a report (Making smart phones smarter with photonics) published in The Optical Society’s photonics journal, Optics Express.
www.polymtl.ca/en


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