Next-gen smartphones could have sensors built into display glass

Gorilla Glass could be getting a lot more useful. Corning International, which makes the material commonly used in mobile device screens, has teamed up with researchers at Polytechnique Montreal to create a new type of glass that incorporates transparent sensors. Soon, the glass in your smartphone screen could be used to take your temperature, among many other possibilities.

The team used lasers to carve photonic waveguides into regular Gorilla Glass, at varying levels within the thickness of the glass. Each one of these acts as a tunnel, which photons can travel through in the same way that electrical currents flow through copper wires.

The researchers have already used the technology to create a temperature sensor, which consists of a curved and a straight waveguide. As the temperature of the glass increases, the glass expands and the length of the two waveguides changes. That change in length in turn affects the way in which light coming out of one waveguide interferes with light coming out of the other. By analyzing that interference, it's possible to accurately gauge the temperature of anything touching the glass.

Additionally, a system has been developed that could be used to verify the user identity of a smartphone – which would come in handy if the phone were being used to conduct a financial transaction, for instance.

In this case, waveguides have holes drilled in them at various locations, those locations being unique to each phone. When someone wanted to authenticate the phone, they could shine infrared light on its screen, and use an infrared detector to analyze the pattern of light escaping from the holes. That pattern would have to match one that was already on file for that phone.

The laser-writing setup used in the research (Photo: Jerome Lapointe)

This certainly isn't the first time that researchers have experimented with photonic waveguides, although it is the first time that they have been created in Gorilla Glass. Additionally, the laser method used this time around is reportedly much cheaper and simpler than the photolithography process that has previously been used, plus it allows the waveguides to be made at various depths throughout the glass instead of just at the surface. This means that multiple sensors could even be stacked one on top of the other, in the same part of the screen.

Along with mobile devices, the technology could also find its way into things like biomedical devices, or even windows or tabletops that would have touchscreen functionality.