Force Sensing Resistors

April 30, 2019

Some info about force sensors

Force Sensing Resistors (FSRs)

FSRs are a type of robust polymer thick film (PTF) that decrease in resistance with an increase of force applied to the surface of the sensor. We will be Working with the interlink FSR 406. The interlink is part of the single zone FSRs family, with optimized force sensitivity for use in human touch control of electronic devices.

Force Sensing Resistors

Technical Details

  • Sensitivity range from 0.1N to 100N of force;
  • 0.45mm thick;
  • Handles up to 10M actuations;
  • 10MΩ when non actuated;
  • Non linear Resistor, so changes of force are not linear to changes in resistance, especially in the end of the sensing range (~4V and up);

Examples

Pressure Sensor with Sampling and Basic Filtering

Lets make a pressure sensor using a voltage divider circuit and the arduino!

Schematic

The common way to use this transducer is with the use of a voltage divider circuit. $R_1$’s value will change the way the voltage curve(for $V_1$ ) is for different pressures (the lower the resistance, the more low pressure values are spread out, and the curve becomes more ‘stretched’), lets see a common voltage divider, and our particular case:

Schematic

Here’s the whole sensor system diagram:

Sensor system diagram

You can find the example of code here.

Results

Let’s see what the console looks like in the end!

Result

You can find an example of code with 12 FSR here.

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