Here we will show how to use a force resistive sensor with your Arduino. The force sensor works like a potentiometer, with more force, we have less resistance. For example, if nothing is pressing the sensor, the resistance will be the maximum of 20Mohm. If the force is high, the resistance tends to 0. This sensor can measure forces between 1kN to 100kN. You can easily use the gravity acceleration to measure object weights. Also, the sensor only measure forces applied to the highlighted area in red below. If the object is positioned outside that area, we can get a wrong read.
To test the sensor, pick a multimeter to measure the resistance. Press the sensor and observe the values changing.
With your Arduino board and a 100K resistor, make this circuit:
Then, upload the following code:
Open the serial monitor (last button on your 1.0 IDE). You should see a number ranging from 0 to 1023. Make some pressure on your sensor and observe the values. These values represents a voltage between 0 and 5V read by the Arduino. We made a resistor divider, if the resistance is exactly 100kohm, the value will be 512. As the sensor resistance gets higher, that value will get higher.