Now, a new Apple patent suggests that the company is also working on off-screen fingerprint technology, and that the feature may be on the apple watch before the iPhone. According to patently apple, the Apple patent was filed in the second quarter of 2018 and recently released in connection with the apple watch. The patent describes the insertion of an antenna in the strap, but also states that the display of a watch may include "one or more input devices, such as a touch sensitive device, a temperature sensitive device, or a fingerprint sensor."
Currently, apple watch relies on pairing and proximity to iPhone for authentication, but this is not ideal. In addition, a complex system like face ID is obviously not suitable for Apple watch, so off screen fingerprint may be a more appropriate solution.
With regard to the antenna in the strap, apple pointed out that the antenna needs some special functions, such as being able to stretch, bend and bend and keep comfortable.