I have fabricated a wifi temperature sensor for my IoT project, IoT Plan.
The sensor board uses an ESP32 module for its core functionality: controller, wifi and temperature sensor. I paired it with a buck-boost voltage regulator that can be supplied by battery (3V) or micro-usb (5V) source. A 4-bit device Id can be configured using jumpers on GPIO pins. The intent is to use the ESP32 module's temperature sensor, however there is on-board support a for a DB18B20 temperature sensor. The circuit diagram follows.