I'm working on a project that's using a 2.2 inch spectra symbol flex sensor (https://www.sparkfun.com/products/10264) mounted on a glove to control a servo. Testing with a multimeter revealed a resistance rage of about 20k to 80k, so I constructed a voltage divider (5v connected to the flex sensor, and a 47k resistor going to ground), connecting the output to the A0 pin, as with any other resistive sensor.
Something isn't working properly, though, because when I look at the values from the analogRead function, they only range from about 1 to 6. I checked to see that the voltage divider was working with a multimeter and got values ranging from .5 to 2v, but for some reason the arduino isn't properly detecting the change. Replacing the flex sensor with a variable resistor produced normal analogRead values from ~22 to 1024, and a few other sensors also seemed to work normally.
I tried changing the value of the resistor in the voltage divider, and found that even when it was removed completely, the value continued to stay between 1 and 6. The datasheet for the flex sensor recommended the use of an impedance buffer, which I tried, but that failed to produce any significant change. Of course, I had never used an op-amp before, so I might have been constructed incorrectly.
Any ideas as to what might be going wrong, and how to fix it?