A mobile thermal sensor system, a mobile device case, and a process for fabricating a mobile thermal sensor system are described that include using a heat spreader (e.g., a heat sink). In an implementation, the mobile thermal sensor system includes a substrate configured to support an electrical component; a thermal detector package coupled to the substrate, the thermal detector package including a first thermopile, a second thermopile, and a reference temperature detector; and a heat spreader coupled to the substrate. In another implementation, a mobile device case can include a case configured to house a mobile device, where the mobile device includes a mobile thermal sensor system.