A retrographic sensor includes a transparent structure, a transparent elastomeric pad, and an at least partially reflective layer. One or more excitation light sources emit light toward a side surface of the transparent structure. The side surface may include a fluorescent layer, where the light from the one or more excitation light sources excites fluorescent emissions from the fluorescent layer. The fluorescent emissions may illuminate the at least partially reflective layer.

Systems and methods having a touchless operating panel with buttons and an electronic circuit (EC). The system including a proximity sensor (PS) associated with an associated button and positioned proximate thereto. The PS arranged to generate a button detection zone around the associated button and detect a presence within the button detection zone. When the PS detects a presence of an object within the button detection zone in a time period, the EC receives proximity values about the detection from the PS. The EC detects if activation of the PS is intentional or unintentional, based on inputting into an activation assessment module, the received proximity values and any other proximity values received from one or more other PSs. When a detection is made that the PS is intentionally activated regarding the presence of the object within the button detection zone. The EC generates and emits a command action.

Methods, systems, and devices for wearing detection are described. A method may include directing light from a first light emitting element to a first light detecting element via an optical interface, at least one of the first light emitting element or the first light detecting element dedicated to detecting a level of surface contact at the optical interface. The method may include measuring, via the first light detecting element, an amount of escaped light which escaped the optical interface, where the amount of escaped light is indicative of the level of surface contact. The method may further include controlling an activation of a second light emitting element and a second light detecting element based on the level of surface contact, at least one of the second light emitting element or the second light detecting element dedicated to measuring a physiological phenomenon at a user of the wearable device.