Sony is also launching a modest update of its Android-compatible SmartWatch, while heavyweights Apple and Google have shown some tentative signs of interest in developing such technology.

The market potential, cheerleaders say, is vast. Leveraging advances in voice technology, biometrics, communications, cloud storage and power consumption, smartwatches and other wearable devices could be a US$50 billion market by 2017, according to Credit Suisse.

"Look at the way we experience mobile communication today - this is not the endpoint," says Andrew Sheehy, the chief analyst at British-based consultancy Generator Research.

Sheehy points to the awkwardness with which people clasp their phones to their ears, remove them from pockets to read messages, or tap in appointments and e-mails. "If you look at the phone today, it's important to ask: Is this as good as it gets?"

Wearable devices such as smartwatches or digital eyewear, the argument goes, could take over many of the more cumbersome functions of a smartphone while also adding functions one can so far only dream of.

By tapping into sensors around the body, on objects and in other devices, they can offer what Plantronics, a headset maker, calls "contextual intelligence", harvesting data to create "a highly personalised experience in real time", says Joe Burton, the company's chief technology officer.

Driving this optimism are advances in technology, and a more sophisticated audience already familiar with smartphones, software applications, and wireless-communication protocols such as Bluetooth.

The prices and size of sensors have fallen rapidly - making them a feature of many smartphones. Samsung's Galaxy S4 has nine, according to a report on wearable technology by Credit Suisse.

An addition to Bluetooth, for example, uses much less energy and can push and pull data to a watch through a mobile phone, says Paul Williamson of CSR, a maker of such so-called Bluetooth smart chips.

With the technology now integrated into devices running the latest versions of Apple's iOS and Google's Android operating systems, "smartwatches can render data from any of the applications that are running on your smartphone", Williamson says.

Smartwatches such as the Magellan Echo, for example, can stream data wirelessly from a range of third-party fitness apps on a smartphone, without requiring frequent recharges.

Tim Ensor, the head of connected devices at British-based Cambridge Consultants, which advises companies and develops new technologies, calls the adoption of Bluetooth Smart "a real game changer".

But so far wearables have remained a niche for early adopters, such as fans of Pebble Technology's crowd-funded smartwatch, which has sold 100,000 units since its launch earlier this year, or health-and-fitness enthusiasts embracing Nike's Fuelband or Under Armour's FitBit.

And therein lies the rub, says Sheehy. Most of these players have either thought too small, or lack the heft to be able to break into the mainstream. That not only means having capital and resources, but being able to build on expertise in hardware, software, cloud and processing data.

"This is tough technology," he says. "The companies who can do this are very few and far between."

First there are remaining technological hurdles, such as powering the devices. Batteries will need to be five to 10 times smaller than those in smartphones, says Cosmin Laslau, a mobile-energy analyst at Lux Research, requiring innovation in cell materials such as silicon anodes and packaging - such as Apple's work on flexible batteries.

Then there is a need for better displays. Both Apple and Samsung have been working on curved glass - Samsung is investing more than US$6 billion on displays this year alone, and is planning to launch a curved mobile device later this year, a source says.

The smartwatch also has to be stylish, says Gartner research director Angela McIntyre.