FlexiForce Sensor Instability

Hi guys,

I am attempting to collect force measurements with a 25 lbs FlexiForce force sensitive resistor (FSR) and an Arduino 328. Everything has been smooth in terms of setup and integration with the Arduino so far. The FSR is part of a +5V voltage divider circuit which sends a varying input to Analog Pin 0. The +5V source is from the Arduino output. When attempting to calibrate, I came across a drifting Analog input. Attached is a graph of data taken with a 1.1 lbs weight resting on the sensor over about two minutes.

Any ideas what’s going on? I have tried troubleshooting and it seems the resistance of the FSR is constant for a constant force application.


Which Arduino output is the 5v source?


The 5V power pin. It is not a digital out pin.

Update: Figured out the sensor I am using is the culprit. Isolated it from the circuit and its drifting all over the place.....may be the trim job I did to it or the PlastiDip coating.....

Have another sensor I can replace it with.