HOW TO EVALUATE LOOMIA FORCE SENSITIVE RESISTORS (FSRs)

Reliable testing methods for accurate pressure sensor evaluation.

Learn how to test Loomia force-sensitive resistors using Arduino setups, laboratory equipment, and controlled testing techniques for consistent results.

Buy a Loomia FSR

Depending on the equipment in your lab, we present three methods for evaluation:

  1. Static weight testing with Arduino

  2. Lab testing with an Instron or similar equipment

  3. Bonus note: Why static weight testing with a multimeter can be misleading

Test 1: For Mini and Mega FSRs

Steps Photos
Arduino Setup
Open the Arduino app and connect the Arduino Uno board to your laptop. Upload the sensor-reading code. 		Arduino setup
Attach Pogo Pin
Clip the pogo-pin to the Loomia Electronic Layer (LEL). 		Pogo pin connection
Connect to Breadboard
Connect the six-pin pogo-pin to the breadboard. 		Breadboard setup
Resistor Wiring
Connect 680Ω resistors and jumper cables according to the wiring diagram. 		Circuit diagram
Quadrant Verification
Open Serial Monitor and press each quadrant: R1C1 → Quadrant 1 R1C2 → Quadrant 2 R1C3 → Quadrant 3 R2C1 → Quadrant 4 R2C2 → Quadrant 5 R2C3 → Quadrant 6 R3C1 → Quadrant 7 R3C2 → Quadrant 8 R3C3 → Quadrant 9 Confirm correct mapping. 		Quadrant test
Sensor Placement
Place the sensor on a glass base after verification. 		Sensor placement
Testing Jig Placement
Place the designated testing jig on top of the sensor. 		Testing jig

Test 2 Testing Steps 

  1. Copy the QC Template to a new spreadsheet to test the sensors. 

  2. Input the “Starting Range” before any weight is applied. 

    a) Most of the quadrants should be zeroed out with the Arduino set up. Although with the testing jig on top, there may be a few quadrants that jump between the 0-10 range, that's acceptable.  

    i) If any quadrants are above the 10 range, try to adjust the testing jig to see if it fixes the issue.  

    ii) If the issue persists even without a testing jig, there may be an issue with that sensor. Move it aside for further inspection. 

  3. To shorten our QC testing, we are only testing 30 grams and 500 grams on 3 diagonal quadrants: 1,5,9.  

    a) 30g= Weight bar, 10g, 10g 

    b) 500g= Weight bar, 10g, 10g, 20g, 50g, 100g, 100g, 100g, 100g 

  4. Place the 30g in quadrant 1, and record the range displayed. 

  5. Repeat Step 4 for quadrants 5 and 9. 

  6. Place the 500g in quadrant 1, and record the range displayed. 

  7. Repeat Step 6 for quadrants 5 and 9. 

  8. If the range is within the max and min range of the table below, then the sensor works as expected. If it is significantly above or below this range, move it aside for further inspection.  

Mini Matrix — Min and Max Range
Weight Collective Mean Min Range Max Range
30 g 28.83333 17 43
500 g 478.5 430 505
Mega Matrix — Min and Max Range
Weight Collective Mean Min Range Max Range
30 g 31.3333 10 51
500 g 453.667 424 509