Hello, here I fabricated PVDF nanofiber sheet with 0.5mm thickness, I have tried to use equipment like some simple "sandwich" set up (electrode-fiber-electrode), just by tapping to test its voltage exchangement, but unfortunately everytime I felt it is cannot test nicely and lots of error value ocurred during experiment.

So here I would like to ask some proper way to test nanofiber piezoelectric characteristic and if it possible some referrence will be much help for me, thanks.