Like many other handsets currently on the market, Microsoft's rumored Surface Phone, which will use Windows 10 Mobile, is likely to come with a fingerprint sensor. It would be the first Windows phone to include a fingerprint sensor, and according to a patent, the sensor may also be pretty unique.
In Microsoft's 'Fingerprint Detection with Transparent Cover' patent, the company explains how a thin cover on an electronic device would enable fingerprint scanning on thinner products. This kind of sensor may be what's included in the Surface Phone.
An electronic device includes a transparent cover and a light source disposed at an edge of the transparent cover. The light source is configured to inject light into the transparent cover. The transparent cover guides the light until interaction with a fingerprint ridge at the transparent cover. The electronic device further includes a filter disposed along the transparent cover. The filter is configured to selectively allow the light scattered by the fingerprint ridge to pass through the filter. A detector generates a signal indicative of the scattered light allowed through the filter. - Patent
It still isn't known if the Surface Phone will be one product or the start of a product family.