I came up with the idea of attaching a galvactivator to a cell phone. A galvactivator is a glove that can detect the user's galvanic skin response, which serves as an indication of the user's current level of arousal. I could attach the galvactivator to a serial port, which could then either plug into a computer, or directly into a cell phone with the proper adapters. Then the galvactivator could send readings of the user's current galvanic skin response to the phone. The phone application could take this information, and use it to graphically display the user's arousal level, along with the face that was chosen to represent the user's current emotion.

The image below depicts the galvactivator I used. It is attached to an IRX board, which converts the galvanic skin response signal from analog to digital, and is powered by a 9-volt battery. This device then attaches to a serial port. Through the serial port, the signal from the galvactivator can be sent to a cell phone or a computer.