The Smart Coffee Mug is a prototype of a travel coffee mug that knows when its contents are too hot to drink. When the mug is picked up to take a sip, a light near the top indicates whether the contents are too hot to drink (red), can be drunk carefully (blue), a good temperature to drink (green), or room temperature/cold (off).
The mug uses a capacitive sensor connected to the aluminum foil to detect touch. It is powered by an Arduino Nano 328 and a 9-V battery and uses a OneWire digital thermometer in the bottom, 1 green LED, 1 RGB LED, and aluminum foil. All code was written in Arduino 1.0.1.
The circuit diagram and photos of the wiring are shown below.