If you want a simple sensor that senses finger touch, here is another approach:http://www.kpsec.freeuk.com/trancirc.htm
In the section "Darlington Pair", look at the schematic with the label "Touch switch circuit". I have built these and they are surprisingly sensitive.
The schematic says to use +9V, but I have used +5V and it works just fine. Replace the 470-ohm resistor and the LED with a single 10K resistor, and attach the transistor collectors to one of your analog input pins.
The voltage will be +5V when there is no touch, and will drop dramatically when you touch the sensor. In fact, with some experimentation, you should be able to have your program react differently based on how much pressure you apply to the sensor.