According to a patent application published recently by the US Patent & Trademark Office, Microsoft has been entertaining the idea of creating a modular smartwatch featuring a rectangular bent display presenting a Metro-like user interface. The patent reveals that while the watch module itself might be enclosed, the wrist band offers a modular design allowing users to attach a variety of modules which would expand the smartwatch's capabilities beyond its factory limitations.
As detailed in Fig.6 in the image gallery below, the wearable's wrist bands seem to be able and accommodate a number of different modules, ranging from additional memory to a microphone and an antenna module. Another wrist band segment seems to act as an additional power supply, and lastly, it appears that the modular design could also allow for the attachment of extra sensors. Another sketch attached to the patent application focuses more on the watch module itself, which seems to accommodate three front-facing buttons as well as an additional button on one of the edges. It's also worth noting that the smartwatch appears to run a form of Windows OS revolving around the Metro-like user interface, however, while the patent was published by the USPTO only last month, the application itself has quite a long history dating back to 2014. Having said that and if Microsoft is indeed developing this modular smartwatch, there is a possibility that the user interface may have experienced drastic changes by now. The Redmond software giant has been refining the UI of Windows OS over the past few years, and the company is already planning on introducing one of the most ambitious changes to the operating system's UI with the Fluent Design System update set to debut in October 2017. But getting back to the matter at hand, although Microsoft has clearly entertained the idea of a modular smartwatch, unfortunately, there is no guarantee that the company will pursue this particular patent and push it through full production.
Microsoft's previous efforts to join the wearable market led to the creation of the Band series. The original Microsoft Band was introduced in October 2014 and it was followed by the Microsoft Band 2 a year later. Both wrist bands have been discontinued on October 3rd, 2016, and no concrete news of a sequel emerged since.