Force Sensors

Flexiforce pressure is available from Sparkfun and is a force sensor. On one end of this flat sensor are three control pins. On the other end a .375" diameter circle acts as a pressure transducer.

This sensor is ideal for outputting to an A/D (analog to Digital) conversion chip, providing 0v - 4.2v proportional to 0lb - 100lb. The parts provided along with the sensor in this kit can also be used with the RCTIME with the BS2 or the analog input for Max MSP and Jitter.

To attach to the Arduino UNO you would need to use a 10 K ohm resistor as in this sketch below.

CC Arduino.org

This sensor can be used to create pressure mats for instance or for touch sensors.

This force sensor outputs a changing resistance that is related to the force applied to push button. The varying resistance can be used with to estimate force (or weight). This sensor can handle up to 4 Kg of force and goes from a resistance of 500K without pressure to 500 ohms when it is experiencing maximum force. This sensor can be used with the RC time command on the BS2.

You can place a sensor like this under a board with a proper spring to resist the weight that it is receiving to sense the pressure or weight of a person. Digikey or HVWTech.com carries these sensors.