From expanding screens to see-through displays: How tech giants are trying to jazz up their gadgets

• See-through screens, phones that wrap around your wrist and expandable displays - these are all concept tech that gadget makers showed off this week in a bid to stand out from competitors.
• At the Mobile World Congress in Barcelona, companies from Lenovo to ZTE showed off unusual displays on their devices.

See-through screens, phones that wrap around your wrist and expandable displays — these are all concept tech that gadget makers showed off this week, in a bid to stand out from competitors in a cut-throat hardware market.

At the world's largest mobile trade show, the Mobile World Congress in Barcelona, some of the biggest companies in the world showed off some unusual screen technology. While electronics firms have continually improved certain aspects of devices, such as battery life and cameras, the focus in recent years has shifted more toward innovations in displays, especially with the advent of foldable phones.

Screens have also become a focal point, given the increase in the amount of things on our devices.

Many of the MWC displays have also come from companies looking to create a buzz around their products and challenge the likes of Apple and Samsung.

"The sheer dominance of Apple and Samsung in connected devices means that other companies are having to go to great lengths to differentiate their products in an effort to turn consumers' heads," Ben Wood, chief analyst at CCS Insight, told CNBC.

"As a result we are seeing a proliferation of weird and wonderful new designs such as wrist worn phones, rollable screens, virtual 3D displays and more."

Here's some of the screen tech on display at MWC:

Tecno expandable phone

Tecno, a brand under the umbrella of Chinese firm Transsion that is now one of the biggest smartphone players in the world, showed off a handset with an expandable screen.

After pressing a button on the top of the device, the screen enlarges sideways.

Called the Tecno Phantom Ultimate, this is so far a concept device, and there has been no word on whether it will go on sale.

Motorola phone you can wear on your wrist

Motorola showed off a phone at MWC that can be bent in various ways.

One use the company illustrated was how the phone could be contorted to fit around your wrist and match outfits.

The interface on the smartphone adapts depending on which way the phone is bent.

Lenovo see-through laptop

China's Lenovo showed a prototype of a laptop with a see-through display.

The firm, which is the world's largest PC maker, showed how an object can be placed behind the screen and detected by the device's cameras. Information about the object would be displayed on the screen.

ZTE's 3D tablet without glasses

ZTE showed off a second-generation tablet that displays three-dimensional images. Typically, 3D images have required some sort of glasses to view, as is the case with 3D movies in theatres.

But this screen produces a 3D image without glasses.

When CNBC saw the device, the quality of the 3D image depended on the angle from which you viewed the screen.