Pages 287-289 describe how to sense body capacitance using a special QTouch IC. However, an earlier part of the reading suggests how to detect capacitive touch without this chip. What technique or principle could you leverage? How would you go about detecting touch without the IC?

Look over the extensive list of sensors from Tom Igoe's Sensor Workshop class at http://itp.nyu.edu/physcomp/sensors/Reports/Reports . Pick a sensor that's interesting to you, read about its operation, and then describe how it might be used in an interactive device.