Velostat Sensors and sensitivity

Hello,

I am attempting to use a velostat pressure sensor for a project. I have one working but it's not quite as sensitive as I would like it to be. Quite a bit of pressure has to be applied to get a change in the analog readout.

For reference, I am using a 2 x 2 cm square of velostat put in between pieces of aluminum foil. I am using MatLab to program and test it.

Online I have found reference sheets showing much greater sensitivity than I am experiencing, including one where someone scaled it to measure between 0 and 8 oz. Would it help to use a different type of conducting sheet besides aluminum foil? Such as copper foil? Or would that not make much of a difference?

Many thanks