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.