In the past few years, we have covered plenty of thermal imagers for iPhone and Android here. The HIKMICRO B1L is also worth a look. It is a 160 x 120 thermal imaging camera with 25Hz refresh rate, 3.2″ screen, and -4 to 1022F temperature range. It connects to the HIKMICRO Viewer App over WiFi.
The B1L comes with audio alarm and a warning light to let you know when the temperature reading is out of range. It runs on battery for up to 8 hours. It has White Hot, Black Hot, Rainbow, and Ironbow color palettes.[where to get it]