The mobile phone has come a long way from the days of brick-like devices to the keyboard-less, high-tech, touchscreen 4G gizmos we see today.

Now, we might be looking at the next step in the smartphone evolution ladder – where a mobile device could be operated with a simple gesture of your hand.

These days most smartphones are capable of reacting to voice commands but researchers at the University of Illinois at Urbana-Champaign and Dow Electronic Materials want to take it a step further and are already working on the technology that they believe can make this sci-fi dream come to life.

They say the answer lies in a certain type of LEDs developed by the scientists that can emit, sense, and respond to light all at once.

These LEDs are made up of specially engineered nanorods designed to look like a thin film.

Each rod, which measures less than five nanometres in diameter (10,000 times thinner than a strand of hair), consists of three different semiconductor materials.

Researchers Moonsub Shim and Seongyong Cho.
Researchers Moonsub Shim and Seongyong Cho (University of Illinois)


The first semiconductor emits and absorbs visible light, while the other two facilitate and control the flow of electrons to the first material – making these nanorods efficient at both emitting and sensing light.

However, each semiconductor needs to be switched on and off to each carry its function but, luckily, researchers say this can be done at a very high frequency so, ultimately, the user won’t be able to notice the time lag.

Moonsub Shim, lead author of the study, said: “These LEDs are the beginning of enabling displays to do something completely different, moving well beyond just displaying information to be much more interactive devices.

LED motion sensor.
These nanorods can respond to light and motion (University of Illinois)


“That can become the basis for new and interesting designs for a lot of electronics.”

In addition to responding to motion and gestures, these LEDs can also be programmed to automatically adjust their brightness on a pixel-by-pixel basis, taking ambient light into account.

Researchers say they can also harvest light for power – much like solar batteries – and interact with a laser stylus, which could make freehand writing or drawing possible on the phone as well.

LED motion sensor.
The LED displays are also able to interact with each other (University of Illinois)


These nanorod LED displays should also be able to interact with each other, although Shim admits the communication would be slower than currently existing device-to-device technologies like Bluetooth.

So far, only red LEDs have been tested and the next step in the plan is to demonstrate the same capabilities with red, blue, and green displays. Scientists are also working on ways to boost the light-harvesting capabilities of these LEDs.

The research is published in the journal Science.

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