Various devices for sterilizing a surface are disclosed. For example, a first device includes an ultraviolet light emitting unit, a processor and a computer-readable medium. The computer-readable medium stores instructions which, when executed by the processor, cause the processor to perform operations. The operations include detecting a proximity of a surface to the ultraviolet light emitting unit and activating the ultraviolet light emitting unit to sterilize the surface in response to the detecting. Another device includes an ultraviolet light emitting unit, a processor and a computer-readable medium. The computer-readable medium stores instructions which, when executed by the processor, cause the processor to perform operations. The operations include storing a location parameter, determining whether location information of the device satisfies the location parameter and activating the ultraviolet light emitting unit when it is determined that the location information of the device satisfies the location parameter.