Various embodiments concern fingerprint sensors for mobile devices. By modifying one or more layers of a display assembly, a fingerprint sensor can be positioned directly beneath the display. For example, the air gap within the backlight structure could be replaced by an optically clear adhesive that allows waves emitted by a fingerprint sensor to properly propagate through the display assembly. In some embodiments, a fingerprint sensor is set within a recess in the display assembly. For example, a depression could be created in the protective substrate, and the fingerprint sensor could be set within the depression using an optically clear adhesive. The functionality of a fingerprint sensor could also be replicated by increasing the density of touch-sensing elements in certain areas of a display assembly that utilizes in-cell technology.