A Google patent suggests that a new Pixel device could end up coming with a rear-facing touchpad surface that would allow users to have extra functionality. Based on the images below, the new device could have a rear-facing touch surface that would be recessed and be accessed by users in the same manner as the rear-facing fingerprint sensor that can be found in the currently available Pixel and Pixel XL. A rear touchpad surface would enable users to do more with their devices, and while such implementations of touch sensitive surfaces haven't exactly been seen or used in smartphones before, it wouldn't be the first time that such technology has been used in any mobile device. Sony for example, has implemented a rear-facing touchpad on its PS Vita handheld consoles since the initial launch of the device, allowing extra functionality and controls for various games that were available for the handheld.
Though there is no guarantee that Google will use such a design element with a future Pixel device, if it did the function would seemingly have predefined gestures that would be integrated and assigned by Google for any number of various features or actions. Google already allows a similar level of gesture functionality on its current Pixel and Pixel XL through the fingerprint sensor. These gestures allow users to swipe down or up to reveal or hide the notifications shade. Though limited in its application, it's opened up the possibility for future implementation of gestures that would expand the actions that are capable.
According to figure 3, it looks like Google's idea would be to include a touch-based surface area that surrounds what looks like the rear-facing fingerprint sensor. This larger touch-based surface area would potentially allow for drawing gestures on the surface to complete certain functions like launching apps or shortcuts. Though the recessed surface area isn't labeled as a fingerprint sensor it holds the same shape as the one on the Pixel which is recessed itself. The patent also envisions the camera being placed in the middle of the device instead of the top left corner, along with a speaker just to the right of it. The uses for the rear-facing touch-based surface area could include any number of actions, such as scrolling through web pages, zooming in and out f images, managing volume for music and more.